Sample records for implantable 96-channel neural

  1. Spatial channel interactions in cochlear implants

    NASA Astrophysics Data System (ADS)

    Tang, Qing; Benítez, Raul; Zeng, Fan-Gang

    2011-08-01

    The modern multi-channel cochlear implant is widely considered to be the most successful neural prosthesis owing to its ability to restore partial hearing to post-lingually deafened adults and to allow essentially normal language development in pre-lingually deafened children. However, the implant performance varies greatly in individuals and is still limited in background noise, tonal language understanding, and music perception. One main cause for the individual variability and the limited performance in cochlear implants is spatial channel interaction from the stimulating electrodes to the auditory nerve and brain. Here we systematically examined spatial channel interactions at the physical, physiological, and perceptual levels in the same five modern cochlear implant subjects. The physical interaction was examined using an electric field imaging technique, which measured the voltage distribution as a function of the electrode position in the cochlea in response to the stimulation of a single electrode. The physiological interaction was examined by recording electrically evoked compound action potentials as a function of the electrode position in response to the stimulation of the same single electrode position. The perceptual interactions were characterized by changes in detection threshold as well as loudness summation in response to in-phase or out-of-phase dual-electrode stimulation. To minimize potentially confounding effects of temporal factors on spatial channel interactions, stimulus rates were limited to 100 Hz or less in all measurements. Several quantitative channel interaction indexes were developed to define and compare the width, slope and symmetry of the spatial excitation patterns derived from these physical, physiological and perceptual measures. The electric field imaging data revealed a broad but uniformly asymmetrical intracochlear electric field pattern, with the apical side producing a wider half-width and shallower slope than the basal

  2. Longterm infrared neural stimulation in the chronic implanted cat

    NASA Astrophysics Data System (ADS)

    Matic, Agnella Izzo; Robinson, Alan M.; Young, Hunter K.; Badofsky, Ben; Rajguru, Suhrud M.; Richter, Claus-Peter

    2013-03-01

    Among neural prostheses cochlear implants (CIs) are considered the most successful devices. They restore some hearing to 210,000 severe-to-profound hearing impaired people. Despite the devices' success, the performance of the implanted individuals in noisy environments is poor and music perception is rudimentary. It has been argued that increasing the number of independent channels for stimulation can improve the performance of a CI user in challenging hearing environments. An optical method, stimulating neurons with infrared radiation, has been suggested as a novel approach to increase the number of independent channels. Infrared neural stimulation (INS) works through the deposition of heat into the tissue. Thermal damage is therefore a potential risk, particularly for longterm exposure. To verify the efficacy and safety of INS, cats were implanted for about 4 weeks and were continuously stimulated daily for 6-8 hours. Cochlear function did not change during the stimulation, and histology did not reveal signs of damage. Tissue growth following the implantation was largely localized at the cochleostomy.

  3. A novel method for extraction of neural response from single channel cochlear implant auditory evoked potentials.

    PubMed

    Sinkiewicz, Daniel; Friesen, Lendra; Ghoraani, Behnaz

    2017-02-01

    Cortical auditory evoked potentials (CAEP) are used to evaluate cochlear implant (CI) patient auditory pathways, but the CI device produces an electrical artifact, which obscures the relevant information in the neural response. Currently there are multiple methods, which attempt to recover the neural response from the contaminated CAEP, but there is no gold standard, which can quantitatively confirm the effectiveness of these methods. To address this crucial shortcoming, we develop a wavelet-based method to quantify the amount of artifact energy in the neural response. In addition, a novel technique for extracting the neural response from single channel CAEPs is proposed. The new method uses matching pursuit (MP) based feature extraction to represent the contaminated CAEP in a feature space, and support vector machines (SVM) to classify the components as normal hearing (NH) or artifact. The NH components are combined to recover the neural response without artifact energy, as verified using the evaluation tool. Although it needs some further evaluation, this approach is a promising method of electrical artifact removal from CAEPs. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  4. A fully integrated mixed-signal neural processor for implantable multichannel cortical recording.

    PubMed

    Sodagar, Amir M; Wise, Kensall D; Najafi, Khalil

    2007-06-01

    A 64-channel neural processor has been developed for use in an implantable neural recording microsystem. In the Scan Mode, the processor is capable of detecting neural spikes by programmable positive, negative, or window thresholding. Spikes are tagged with their associated channel addresses and formed into 18-bit data words that are sent serially to the external host. In the Monitor Mode, two channels can be selected and viewed at high resolution for studies where the entire signal is of interest. The processor runs from a 3-V supply and a 2-MHz clock, with a channel scan rate of 64 kS/s and an output bit rate of 2 Mbps.

  5. A Fully-Implantable Cochlear Implant SoC with Piezoelectric Middle-Ear Sensor and Arbitrary Waveform Neural Stimulation.

    PubMed

    Yip, Marcus; Jin, Rui; Nakajima, Hideko Heidi; Stankovic, Konstantina M; Chandrakasan, Anantha P

    2015-01-01

    A system-on-chip for an invisible, fully-implantable cochlear implant is presented. Implantable acoustic sensing is achieved by interfacing the SoC to a piezoelectric sensor that detects the sound-induced motion of the middle ear. Measurements from human cadaveric ears demonstrate that the sensor can detect sounds between 40 and 90 dB SPL over the speech bandwidth. A highly-reconfigurable digital sound processor enables system power scalability by reconfiguring the number of channels, and provides programmable features to enable a patient-specific fit. A mixed-signal arbitrary waveform neural stimulator enables energy-optimal stimulation pulses to be delivered to the auditory nerve. The energy-optimal waveform is validated with in-vivo measurements from four human subjects which show a 15% to 35% energy saving over the conventional rectangular waveform. Prototyped in a 0.18 μ m high-voltage CMOS technology, the SoC in 8-channel mode consumes 572 μ W of power including stimulation. The SoC integrates implantable acoustic sensing, sound processing, and neural stimulation on one chip to minimize the implant size, and proof-of-concept is demonstrated with measurements from a human cadaver ear.

  6. Enhanced biocompatibility of neural probes by integrating microstructures and delivering anti-inflammatory agents via microfluidic channels

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Kim, Eric; Meggo, Anika; Gandhi, Sachin; Luo, Hao; Kallakuri, Srinivas; Xu, Yong; Zhang, Jinsheng

    2017-04-01

    Objective. Biocompatibility is a major issue for chronic neural implants, involving inflammatory and wound healing responses of neurons and glial cells. To enhance biocompatibility, we developed silicon-parylene hybrid neural probes with open architecture electrodes, microfluidic channels and a reservoir for drug delivery to suppress tissue responses. Approach. We chronically implanted our neural probes in the rat auditory cortex and investigated (1) whether open architecture electrode reduces inflammatory reaction by measuring glial responses; and (2) whether delivery of antibiotic minocycline reduces inflammatory and tissue reaction. Four weeks after implantation, immunostaining for glial fibrillary acid protein (astrocyte marker) and ionizing calcium-binding adaptor molecule 1 (macrophages/microglia cell marker) were conducted to identify immunoreactive astrocyte and microglial cells, and to determine the extent of astrocytes and microglial cell reaction/activation. A comparison was made between using traditional solid-surface electrodes and newly-designed electrodes with open architecture, as well as between deliveries of minocycline and artificial cerebral-spinal fluid diffused through microfluidic channels. Main results. The new probes with integrated micro-structures induced minimal tissue reaction compared to traditional electrodes at 4 weeks after implantation. Microcycline delivered through integrated microfluidic channels reduced tissue response as indicated by decreased microglial reaction around the neural probes implanted. Significance. The new design will help enhance the long-term stability of the implantable devices.

  7. A method for compression of intra-cortically-recorded neural signals dedicated to implantable brain-machine interfaces.

    PubMed

    Shaeri, Mohammad Ali; Sodagar, Amir M

    2015-05-01

    This paper proposes an efficient data compression technique dedicated to implantable intra-cortical neural recording devices. The proposed technique benefits from processing neural signals in the Discrete Haar Wavelet Transform space, a new spike extraction approach, and a novel data framing scheme to telemeter the recorded neural information to the outside world. Based on the proposed technique, a 64-channel neural signal processor was designed and prototyped as a part of a wireless implantable extra-cellular neural recording microsystem. Designed in a 0.13- μ m standard CMOS process, the 64-channel neural signal processor reported in this paper occupies ∼ 0.206 mm(2) of silicon area, and consumes 94.18 μW when operating under a 1.2-V supply voltage at a master clock frequency of 1.28 MHz.

  8. Sub-meninges implantation reduces immune response to neural implants.

    PubMed

    Markwardt, Neil T; Stokol, Jodi; Rennaker, Robert L

    2013-04-15

    Glial scar formation around neural interfaces inhibits their ability to acquire usable signals from the surrounding neurons. To improve neural recording performance, the inflammatory response and glial scarring must be minimized. Previous work has indicated that meningeally derived cells participate in the immune response, and it is possible that the meninges may grow down around the shank of a neural implant, contributing to the formation of the glial scar. This study examines whether the glial scar can be reduced by placing a neural probe completely below the meninges. Rats were implanted with sets of loose microwire implants placed either completely below the meninges or implanted conventionally with the upper end penetrating the meninges, but not attached to the skull. Histological analysis was performed 4 weeks following surgical implantation to evaluate the glial scar. Our results found that sub-meninges implants showed an average reduction in reactive astrocyte activity of 63% compared to trans-meninges implants. Microglial activity was also reduced for sub-meninges implants. These results suggest that techniques that isolate implants from the meninges offer the potential to reduce the encapsulation response which should improve chronic recording quality and stability. Published by Elsevier B.V.

  9. Sub-meninges Implantation Reduces Immune Response to Neural Implants

    PubMed Central

    Markwardt, Neil T.; Stokol, Jodi; Rennaker, Robert L.

    2013-01-01

    Glial scar formation around neural interfaces inhibits their ability to acquire usable signals from the surrounding neurons. To improve neural recording performance, the inflammatory response and glial scarring must be minimized. Previous work has indicated that meningeally derived cells participate in the immune response, and it is possible that the meninges may grow down around the shank of a neural implant, contributing to the formation of the glial scar. This study examines whether the glial scar can be reduced by placing a neural probe completely below the meninges. Rats were implanted with sets of loose microwire implants placed either completely below the meninges or implanted conventionally with the upper end penetrating the meninges, but not attached to the skull. Histological analysis was performed 4 weeks following surgical implantation to evaluate the glial scar. Our results found that sub-meninges implants showed an average reduction in reactive astrocyte activity of 63% compared to trans-meninges implants. Microglial activity was also reduced for sub-meninges implants. These results suggest that techniques that isolate implants from the meninges offer the potential to reduce the encapsulation response which should improve chronic recording quality and stability. PMID:23370311

  10. A 32-channel fully implantable wireless neurosensor for simultaneous recording from two cortical regions.

    PubMed

    Aceros, Juan; Yin, Ming; Borton, David A; Patterson, William R; Nurmikko, Arto V

    2011-01-01

    We present a fully implantable, wireless, neurosensor for multiple-location neural interface applications. The device integrates two independent 16-channel intracortical microelectrode arrays and can simultaneously acquire 32 channels of broadband neural data from two separate cortical areas. The system-on-chip implantable sensor is built on a flexible Kapton polymer substrate and incorporates three very low power subunits: two cortical subunits connected to a common subcutaneous subunit. Each cortical subunit has an ultra-low power 16-channel preamplifier and multiplexer integrated onto a cortical microelectrode array. The subcutaneous epicranial unit has an inductively coupled power supply, two analog-to-digital converters, a low power digital controller chip, and microlaser-based infrared telemetry. The entire system is soft encapsulated with biocompatible flexible materials for in vivo applications. Broadband neural data is conditioned, amplified, and analog multiplexed by each of the cortical subunits and passed to the subcutaneous component, where it is digitized and combined with synchronization data and wirelessly transmitted transcutaneously using high speed infrared telemetry.

  11. Electrophysiological channel interactions using focused multipolar stimulation for cochlear implants

    NASA Astrophysics Data System (ADS)

    George, Shefin S.; Shivdasani, Mohit N.; Wise, Andrew K.; Shepherd, Robert K.; Fallon, James B.

    2015-12-01

    Objective. Speech intelligibility with existing multichannel cochlear implants (CIs) is thought to be limited by poor spatial selectivity and interactions between CI channels caused by overlapping activation with monopolar (MP) stimulation. Our previous studies have shown that focused multipolar (FMP) and tripolar (TP) stimulation produce more restricted neural activation in the inferior colliculus (IC), compared to MP stimulation. Approach. This study explored interactions in the IC produced by simultaneous stimulation of two CI channels. We recorded multi-unit neural activity in the IC of anaesthetized cats with normal and severely degenerated spiral ganglion neuron populations in response to FMP, TP and MP stimulation from a 14 channel CI. Stimuli were applied to a ‘fixed’ CI channel, chosen toward the middle of the cochlear electrode array, and the effects of simultaneously stimulating a more apical ‘test’ CI channel were measured as a function of spatial separation between the two stimulation channels and stimulus level of the fixed channel. Channel interactions were quantified by changes in neural responses and IC threshold (i.e., threshold shift) elicited by simultaneous stimulation of two CI channels, compared to stimulation of the test channel alone. Main results. Channel interactions were significantly lower for FMP and TP than for MP stimulation (p < 0.001), whereas no significant difference was observed between FMP and TP stimulation. With MP stimulation, threshold shifts increased with decreased inter-electrode spacing and increased stimulus levels of the fixed channel. For FMP and TP stimulation, channel interactions were found to be similar for different inter-electrode spacing and stimulus levels of the fixed channel. Significance. The present study demonstrates how the degree of channel interactions in a CI can be controlled using stimulation configurations such as FMP and TP; such knowledge is essential in enhancing CI function in complex

  12. A Wireless 32-Channel Implantable Bidirectional Brain Machine Interface

    PubMed Central

    Su, Yi; Routhu, Sudhamayee; Moon, Kee S.; Lee, Sung Q.; Youm, WooSub; Ozturk, Yusuf

    2016-01-01

    All neural information systems (NIS) rely on sensing neural activity to supply commands and control signals for computers, machines and a variety of prosthetic devices. Invasive systems achieve a high signal-to-noise ratio (SNR) by eliminating the volume conduction problems caused by tissue and bone. An implantable brain machine interface (BMI) using intracortical electrodes provides excellent detection of a broad range of frequency oscillatory activities through the placement of a sensor in direct contact with cortex. This paper introduces a compact-sized implantable wireless 32-channel bidirectional brain machine interface (BBMI) to be used with freely-moving primates. The system is designed to monitor brain sensorimotor rhythms and present current stimuli with a configurable duration, frequency and amplitude in real time to the brain based on the brain activity report. The battery is charged via a novel ultrasonic wireless power delivery module developed for efficient delivery of power into a deeply-implanted system. The system was successfully tested through bench tests and in vivo tests on a behaving primate to record the local field potential (LFP) oscillation and stimulate the target area at the same time. PMID:27669264

  13. Embedded electronics for a 64-channel wireless brain implant

    NASA Astrophysics Data System (ADS)

    Burgert, Johann D.; Malasek, Jan; Martel, Sylvain M.; Wiseman, Colette; Fofonoff, Timothy; Dyer, Robert; Hunter, Ian W.; Hatsopoulos, Nicholas; Donoghue, John

    2001-10-01

    The Telemetric Electrode Array System (TEAS) is a surgically implantable device for the study of neural activity in the brain. An 8x8 array of electrodes collects intra-cortical neural signals and connects them to an analog front end. The front end amplifies and digitizes these microvolt-level signals with 12 bits of resolution and at 31KHz per channel. Peak detection is used to extract the information carrying features of these signals, which are transmitted over a Bluetooth-based radio link at 725 Kbit/sec. The electrode array is made up of 1mm tall, 60-micron square electrodes spaced 500 microns tip-to-tip. A flex circuit connector provides mechanical isolation between the brain and the electronics, which are mounted to the cranium. Power consumption and management is a critical aspect of the design. The entire system must operate off a surgically implantable battery. With this power source, the system must provide the functionality of a wireless, 64-channel oscilloscope for several hours. The system also provides a low-power sleep mode during which the battery can be inductively charged. Power dissipation and biocompatibility issues also affect the design of the electronics for the probe. The electronics system must fit between the skull and the skin of the test subject. Thus, circuit miniaturization and microassembly techniques are essential to construct the probe's electronics.

  14. A 100-Channel Hermetically Sealed Implantable Device for Chronic Wireless Neurosensing Applications

    PubMed Central

    Yin, Ming; Borton, David A.; Aceros, Juan; Patterson, William R.; Nurmikko, Arto V.

    2014-01-01

    A 100-channel fully implantable wireless broadband neural recording system was developed. It features 100 parallel broadband (0.1 Hz–7.8 kHz) neural recording channels, a medical grade 200 mAh Li-ion battery recharged inductively at 150 kHz, and data telemetry using 3.2 GHz to 3.8 GHz FSK modulated wireless link for 48 Mbps Manchester encoded data. All active electronics are hermetically sealed in a titanium enclosure with a sapphire window for electromagnetic transparency. A custom, high-density configuration of 100 individual hermetic feedthrough pins enable connection to an intracortical neural recording microelectrode array. A 100 MHz bandwidth custom receiver was built to remotely receive the FSK signal and achieved −77.7 dBm sensitivity with 10−8 BER at 48 Mbps data rate. ESD testing on all the electronic inputs and outputs has proven that the implantable device satisfies the HBM Class-1B ESD Standard. In addition, the evaluation of the worst-case charge density delivered to the tissue from each I/O pin verifies the patient safety of the device in the event of failure. Finally, the functionality and reliability of the complete device has been tested on-bench and further validated chronically in ongoing freely moving swine and monkey animal trials for more than one year to date. PMID:23853294

  15. Feasibility study for future implantable neural-silicon interface devices.

    PubMed

    Al-Armaghany, Allann; Yu, Bo; Mak, Terrence; Tong, Kin-Fai; Sun, Yihe

    2011-01-01

    The emerging neural-silicon interface devices bridge nerve systems with artificial systems and play a key role in neuro-prostheses and neuro-rehabilitation applications. Integrating neural signal collection, processing and transmission on a single device will make clinical applications more practical and feasible. This paper focuses on the wireless antenna part and real-time neural signal analysis part of implantable brain-machine interface (BMI) devices. We propose to use millimeter-wave for wireless connections between different areas of a brain. Various antenna, including microstrip patch, monopole antenna and substrate integrated waveguide antenna are considered for the intra-cortical proximity communication. A Hebbian eigenfilter based method is proposed for multi-channel neuronal spike sorting. Folding and parallel design techniques are employed to explore various structures and make a trade-off between area and power consumption. Field programmable logic arrays (FPGAs) are used to evaluate various structures.

  16. A preferential design approach for energy-efficient and robust implantable neural signal processing hardware.

    PubMed

    Narasimhan, Seetharam; Chiel, Hillel J; Bhunia, Swarup

    2009-01-01

    For implantable neural interface applications, it is important to compress data and analyze spike patterns across multiple channels in real time. Such a computational task for online neural data processing requires an innovative circuit-architecture level design approach for low-power, robust and area-efficient hardware implementation. Conventional microprocessor or Digital Signal Processing (DSP) chips would dissipate too much power and are too large in size for an implantable system. In this paper, we propose a novel hardware design approach, referred to as "Preferential Design" that exploits the nature of the neural signal processing algorithm to achieve a low-voltage, robust and area-efficient implementation using nanoscale process technology. The basic idea is to isolate the critical components with respect to system performance and design them more conservatively compared to the noncritical ones. This allows aggressive voltage scaling for low power operation while ensuring robustness and area efficiency. We have applied the proposed approach to a neural signal processing algorithm using the Discrete Wavelet Transform (DWT) and observed significant improvement in power and robustness over conventional design.

  17. Effects of cochlear-implant pulse rate and inter-channel timing on channel interactions and thresholds

    NASA Astrophysics Data System (ADS)

    Middlebrooks, John C.

    2004-07-01

    Interactions among the multiple channels of a cochlear prosthesis limit the number of channels of information that can be transmitted to the brain. This study explored the influence on channel interactions of electrical pulse rates and temporal offsets between channels. Anesthetized guinea pigs were implanted with 2-channel scala-tympani electrode arrays, and spike activity was recorded from the auditory cortex. Channel interactions were quantified as the reduction of the threshold for pulse-train stimulation of the apical channel by sub-threshold stimulation of the basal channel. Pulse rates were 254 or 4069 pulses per second (pps) per channel. Maximum threshold reductions averaged 9.6 dB when channels were stimulated simultaneously. Among nonsimultaneous conditions, threshold reductions at the 254-pps rate were entirely eliminated by a 1966-μs inter-channel offset. When offsets were only 41 to 123 μs, however, maximum threshold shifts averaged 3.1 dB, which was comparable to the dynamic ranges of cortical neurons in this experimental preparation. Threshold reductions at 4069 pps averaged up to 1.3 dB greater than at 254 pps, which raises some concern in regard to high-pulse-rate speech processors. Thresholds for various paired-pulse stimuli, pulse rates, and pulse-train durations were measured to test possible mechanisms of temporal integration.

  18. Investigation of Implantable Multi-Channel Electrode Array in Rat Cerebral Cortex Used for Recording

    NASA Astrophysics Data System (ADS)

    Taniguchi, Noriyuki; Fukayama, Osamu; Suzuki, Takafumi; Mabuchi, Kunihiko

    There have recently been many studies concerning the control of robot movements using neural signals recorded from the brain (usually called the Brain-Machine interface (BMI)). We fabricated implantable multi-electrode arrays to obtain neural signals from the rat cerebral cortex. As any multi-electrode array should have electrode alignment that minimizes invasion, it is necessary to customize the recording site. We designed three types of 22-channel multi-electrode arrays, i.e., 1) wide, 2) three-layered, and 3) separate. The first extensively covers the cerebral cortex. The second has a length of 2 mm, which can cover the area of the primary motor cortex. The third array has a separate structure, which corresponds to the position of the forelimb and hindlimb areas of the primary motor cortex. These arrays were implanted into the cerebral cortex of a rat. We estimated the walking speed from neural signals using our fabricated three-layered array to investigate its feasibility for BMI research. The neural signal of the rat and its walking speed were simultaneously recorded. The results revealed that evaluation using either the anterior electrode group or posterior group provided accurate estimates. However, two electrode groups around the center yielded poor estimates although it was possible to record neural signals.

  19. Toward a distributed free-floating wireless implantable neural recording system.

    PubMed

    Pyungwoo Yeon; Xingyuan Tong; Byunghun Lee; Mirbozorgi, Abdollah; Ash, Bruce; Eckhardt, Helmut; Ghovanloo, Maysam

    2016-08-01

    To understand the complex correlations between neural networks across different regions in the brain and their functions at high spatiotemporal resolution, a tool is needed for obtaining long-term single unit activity (SUA) across the entire brain area. The concept and preliminary design of a distributed free-floating wireless implantable neural recording (FF-WINeR) system are presented, which can enabling SUA acquisition by dispersedly implanting tens to hundreds of untethered 1 mm3 neural recording probes, floating with the brain and operating wirelessly across the cortical surface. For powering FF-WINeR probes, a 3-coil link with an intermediate high-Q resonator provides a minimum S21 of -22.22 dB (in the body medium) and -21.23 dB (in air) at 2.8 cm coil separation, which translates to 0.76%/759 μW and 0.6%/604 μW of power transfer efficiency (PTE) / power delivered to a 9 kΩ load (PDL), in body and air, respectively. A mock-up FF-WINeR is implemented to explore microassembly method of the 1×1 mm2 micromachined silicon die with a bonding wire-wound coil and a tungsten micro-wire electrode. Circuit design methods to fit the active circuitry in only 0.96 mm2 of die area in a 130 nm standard CMOS process, and satisfy the strict power and performance requirements (in simulations) are discussed.

  20. Functional and Histological Effects of Chronic Neural Electrode Implantation.

    PubMed

    Sahyouni, Ronald; Chang, David T; Moshtaghi, Omid; Mahmoodi, Amin; Djalilian, Hamid R; Lin, Harrison W

    2017-04-01

    Permanent injury to the cranial nerves can often result in a substantial reduction in quality of life. Novel and innovative interventions can help restore form and function in nerve paralysis, with bioelectric interfaces among the more promising of these approaches. The foreign body response is an important consideration for any bioelectric device as it influences the function and effectiveness of the implant. The purpose of this review is to describe tissue and functional effects of chronic neural implantation among the different categories of neural implants and highlight advances in peripheral and cranial nerve stimulation. Data Sources : PubMed, IEEE, and Web of Science literature search. Review Methods : A review of the current literature was conducted to examine functional and histologic effects of bioelectric interfaces for neural implants. Bioelectric devices can be characterized as intraneural, epineural, perineural, intranuclear, or cortical depending on their placement relative to nerves and neuronal cell bodies. Such devices include nerve-specific stimulators, neuroprosthetics, brainstem implants, and deep brain stimulators. Regardless of electrode location and interface type, acute and chronic histological, macroscopic and functional changes can occur as a result of both passive and active tissue responses to the bioelectric implant. A variety of chronically implantable electrodes have been developed to treat disorders of the peripheral and cranial nerves, to varying degrees of efficacy. Consideration and mitigation of detrimental effects at the neural interface with further optimization of functional nerve stimulation will facilitate the development of these technologies and translation to the clinic. 3.

  1. Multi-scale, multi-modal analysis uncovers complex relationship at the brain tissue-implant neural interface: new emphasis on the biological interface

    NASA Astrophysics Data System (ADS)

    Michelson, Nicholas J.; Vazquez, Alberto L.; Eles, James R.; Salatino, Joseph W.; Purcell, Erin K.; Williams, Jordan J.; Cui, X. Tracy; Kozai, Takashi D. Y.

    2018-06-01

    Objective. Implantable neural electrode devices are important tools for neuroscience research and have an increasing range of clinical applications. However, the intricacies of the biological response after implantation, and their ultimate impact on recording performance, remain challenging to elucidate. Establishing a relationship between the neurobiology and chronic recording performance is confounded by technical challenges related to traditional electrophysiological, material, and histological limitations. This can greatly impact the interpretations of results pertaining to device performance and tissue health surrounding the implant. Approach. In this work, electrophysiological activity and immunohistological analysis are compared after controlling for motion artifacts, quiescent neuronal activity, and material failure of devices in order to better understand the relationship between histology and electrophysiological outcomes. Main results. Even after carefully accounting for these factors, the presence of viable neurons and lack of glial scarring does not convey single unit recording performance. Significance. To better understand the biological factors influencing neural activity, detailed cellular and molecular tissue responses were examined. Decreases in neural activity and blood oxygenation in the tissue surrounding the implant, shift in expression levels of vesicular transporter proteins and ion channels, axon and myelin injury, and interrupted blood flow in nearby capillaries can impact neural activity around implanted neural interfaces. Combined, these tissue changes highlight the need for more comprehensive, basic science research to elucidate the relationship between biology and chronic electrophysiology performance in order to advance neural technologies.

  2. 96-Channel receive-only head coil for 3 Tesla: design optimization and evaluation.

    PubMed

    Wiggins, Graham C; Polimeni, Jonathan R; Potthast, Andreas; Schmitt, Melanie; Alagappan, Vijay; Wald, Lawrence L

    2009-09-01

    The benefits and challenges of highly parallel array coils for head imaging were investigated through the development of a 3T receive-only phased-array head coil with 96 receive elements constructed on a close-fitting helmet-shaped former. We evaluated several designs for the coil elements and matching circuitry, with particular attention to sources of signal-to-noise ratio (SNR) loss, including various sources of coil loading and coupling between the array elements. The SNR and noise amplification (g-factor) in accelerated imaging were quantitatively evaluated in phantom and human imaging and compared to a 32-channel array built on an identical helmet-shaped former and to a larger commercial 12-channel head coil. The 96-channel coil provided substantial SNR gains in the distal cortex compared to the 12- and 32-channel coils. The central SNR for the 96-channel coil was similar to the 32-channel coil for optimum SNR combination and 20% lower for root-sum-of-squares combination. There was a significant reduction in the maximum g-factor for 96 channels compared to 32; for example, the 96-channel maximum g-factor was 65% of the 32-channel value for acceleration rate 4. The performance of the array is demonstrated in highly accelerated brain images.

  3. Active Microelectronic Neurosensor Arrays for Implantable Brain Communication Interfaces

    PubMed Central

    Song, Y.-K.; Borton, D. A.; Park, S.; Patterson, W. R.; Bull, C. W.; Laiwalla, F.; Mislow, J.; Simeral, J. D.; Donoghue, J. P.; Nurmikko, A. V.

    2010-01-01

    We have built a wireless implantable microelectronic device for transmitting cortical signals transcutaneously. The device is aimed at interfacing a microelectrode array cortical to an external computer for neural control applications. Our implantable microsystem enables presently 16-channel broadband neural recording in a non-human primate brain by converting these signals to a digital stream of infrared light pulses for transmission through the skin. The implantable unit employs a flexible polymer substrate onto which we have integrated ultra-low power amplification with analog multiplexing, an analog-to-digital converter, a low power digital controller chip, and infrared telemetry. The scalable 16-channel microsystem can employ any of several modalities of power supply, including via radio frequency by induction, or infrared light via a photovoltaic converter. As of today, the implant has been tested as a sub-chronic unit in non-human primates (~ 1 month), yielding robust spike and broadband neural data on all available channels. PMID:19502132

  4. Miniaturized neural interfaces and implants

    NASA Astrophysics Data System (ADS)

    Stieglitz, Thomas; Boretius, Tim; Ordonez, Juan; Hassler, Christina; Henle, Christian; Meier, Wolfgang; Plachta, Dennis T. T.; Schuettler, Martin

    2012-03-01

    Neural prostheses are technical systems that interface nerves to treat the symptoms of neurological diseases and to restore sensory of motor functions of the body. Success stories have been written with the cochlear implant to restore hearing, with spinal cord stimulators to treat chronic pain as well as urge incontinence, and with deep brain stimulators in patients suffering from Parkinson's disease. Highly complex neural implants for novel medical applications can be miniaturized either by means of precision mechanics technologies using known and established materials for electrodes, cables, and hermetic packages or by applying microsystems technologies. Examples for both approaches will be introduced and discussed. Electrode arrays for recording of electrocorticograms during presurgical epilepsy diagnosis have been manufactured using approved materials and a marking laser to achieve an integration density that is adequate in the context of brain machine interfaces, e.g. on the motor cortex. Microtechnologies have to be used for further miniaturization to develop polymer-based flexible and light weighted electrode arrays to interface the peripheral and central nervous system. Polyimide as substrate and insulation material will be discussed as well as several application examples for nerve interfaces like cuffs, filament like electrodes and large arrays for subdural implantation.

  5. Restoring motor control and sensory feedback in people with upper extremity amputations using arrays of 96 microelectrodes implanted in the median and ulnar nerves.

    PubMed

    Davis, T S; Wark, H A C; Hutchinson, D T; Warren, D J; O'Neill, K; Scheinblum, T; Clark, G A; Normann, R A; Greger, B

    2016-06-01

    An important goal of neuroprosthetic research is to establish bidirectional communication between the user and new prosthetic limbs that are capable of controlling >20 different movements. One strategy for achieving this goal is to interface the prosthetic limb directly with efferent and afferent fibres in the peripheral nervous system using an array of intrafascicular microelectrodes. This approach would provide access to a large number of independent neural pathways for controlling high degree-of-freedom prosthetic limbs, as well as evoking multiple-complex sensory percepts. Utah Slanted Electrode Arrays (USEAs, 96 recording/stimulating electrodes) were implanted for 30 days into the median (Subject 1-M, 31 years post-amputation) or ulnar (Subject 2-U, 1.5 years post-amputation) nerves of two amputees. Neural activity was recorded during intended movements of the subject's phantom fingers and a linear Kalman filter was used to decode the neural data. Microelectrode stimulation of varying amplitudes and frequencies was delivered via single or multiple electrodes to investigate the number, size and quality of sensory percepts that could be evoked. Device performance over time was assessed by measuring: electrode impedances, signal-to-noise ratios (SNRs), stimulation thresholds, number and stability of evoked percepts. The subjects were able to proportionally, control individual fingers of a virtual robotic hand, with 13 different movements decoded offline (r = 0.48) and two movements decoded online. Electrical stimulation across one USEA evoked >80 sensory percepts. Varying the stimulation parameters modulated percept quality. Devices remained intrafascicularly implanted for the duration of the study with no significant changes in the SNRs or percept thresholds. This study demonstrated that an array of 96 microelectrodes can be implanted into the human peripheral nervous system for up to 1 month durations. Such an array could provide intuitive control of a

  6. Restoring motor control and sensory feedback in people with upper extremity amputations using arrays of 96 microelectrodes implanted in the median and ulnar nerves

    NASA Astrophysics Data System (ADS)

    Davis, T. S.; Wark, H. A. C.; Hutchinson, D. T.; Warren, D. J.; O'Neill, K.; Scheinblum, T.; Clark, G. A.; Normann, R. A.; Greger, B.

    2016-06-01

    Objective. An important goal of neuroprosthetic research is to establish bidirectional communication between the user and new prosthetic limbs that are capable of controlling >20 different movements. One strategy for achieving this goal is to interface the prosthetic limb directly with efferent and afferent fibres in the peripheral nervous system using an array of intrafascicular microelectrodes. This approach would provide access to a large number of independent neural pathways for controlling high degree-of-freedom prosthetic limbs, as well as evoking multiple-complex sensory percepts. Approach. Utah Slanted Electrode Arrays (USEAs, 96 recording/stimulating electrodes) were implanted for 30 days into the median (Subject 1-M, 31 years post-amputation) or ulnar (Subject 2-U, 1.5 years post-amputation) nerves of two amputees. Neural activity was recorded during intended movements of the subject’s phantom fingers and a linear Kalman filter was used to decode the neural data. Microelectrode stimulation of varying amplitudes and frequencies was delivered via single or multiple electrodes to investigate the number, size and quality of sensory percepts that could be evoked. Device performance over time was assessed by measuring: electrode impedances, signal-to-noise ratios (SNRs), stimulation thresholds, number and stability of evoked percepts. Main results. The subjects were able to proportionally, control individual fingers of a virtual robotic hand, with 13 different movements decoded offline (r = 0.48) and two movements decoded online. Electrical stimulation across one USEA evoked >80 sensory percepts. Varying the stimulation parameters modulated percept quality. Devices remained intrafascicularly implanted for the duration of the study with no significant changes in the SNRs or percept thresholds. Significance. This study demonstrated that an array of 96 microelectrodes can be implanted into the human peripheral nervous system for up to 1 month durations. Such an

  7. Spiking neural P systems with multiple channels.

    PubMed

    Peng, Hong; Yang, Jinyu; Wang, Jun; Wang, Tao; Sun, Zhang; Song, Xiaoxiao; Luo, Xiaohui; Huang, Xiangnian

    2017-11-01

    Spiking neural P systems (SNP systems, in short) are a class of distributed parallel computing systems inspired from the neurophysiological behavior of biological spiking neurons. In this paper, we investigate a new variant of SNP systems in which each neuron has one or more synaptic channels, called spiking neural P systems with multiple channels (SNP-MC systems, in short). The spiking rules with channel label are introduced to handle the firing mechanism of neurons, where the channel labels indicate synaptic channels of transmitting the generated spikes. The computation power of SNP-MC systems is investigated. Specifically, we prove that SNP-MC systems are Turing universal as both number generating and number accepting devices. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Hormonal crosstalk with calcium channel blocker during implantation.

    PubMed

    Banerjee, Aryamitra; Padh, Harish; Nivsarkar, Manish

    2011-08-01

    The site specific action of the calcium channel blocker diltiazem in blocking prostaglandin synthesis and hence causing blastocyst implantation failure has been previously described. Based on this understanding it was important to learn if this pathway was under the control of the fine balance in estradiol-progesterone (E2-P4) milieu, considered to be of the utmost significance for effective implantation. In the current study the circulating E2-P4 levels were monitored on the first 6 d of pregnancy at various time points using sensitive chemiluminescence based assays. Next, diltiazem was administered intra-luminally into the uterus at 10-20 h prior to implantation as this time has been previously implicated to be when the best anti-implantation activity of diltiazem can be observed. Following this, the E2-P4 in peripheral circulation was again monitored. On d 6 (post implantation) the implantation sites were observed in the uterus of both diltiazem treated and untreated groups using Chicago blue dye and correlated to the hormonal activity. The levels of both estradiol and progesterone were very similar in both untreated and diltiazem treated groups during and post implantation. However complete implantation failure was noted in the diltiazem treated group whereas prominent implantation sites were observed in the untreated animals. Thus, the previously reported inhibition of blastocyst implantation cascade by calcium channel blockers during the 'implantation window' seems to be an independent mechanism interfering with uterine receptivity without any direct estrogen-progesterone control and further studies to understand its regulation need to be performed.

  9. Contacting the brain--aspects of a technology assessment of neural implants.

    PubMed

    Decker, Michael; Fleischer, Torsten

    2008-12-01

    The public interest in neural implants has grown considerably in recent years. Progress within related research areas in combination with increasing--albeit overly optimistic and indiscriminate--mass media coverage have led to the impression that the possibilities of neural prosthetics have grown enormously. But a closer look reveals that the reasons for the intensified interest are varied and cannot be attributed to technical progress alone. Some neural prostheses that have been under development for many years have not left the clinical development phase despite intensive research activities. Other implants, like cardiac pacemakers and cochlea implants, are mature products that have already been implanted in a large number of patients. From the public perspective and in media reports, progress in the development of neural implants is associated with new achievements in other fields of neuroscience. Communications on new applications of functional magnetic resonance imaging (fMRI) may suggest that a number of cognitive functions are now easily accessible with technological means. The fact that the interpretation of the results of fMRI studies depends on many conditions and is partly disputed also within the scientific community has been discussed in many publications but only very limited, in the general media. Besides this, research results and implementations in the area of electroencephalography and magnetoencephalography have sparked further debate on the question of free will, on determinism and indeterminism, and have attracted a large media response. The purpose of this paper is to discuss some societal and ethical aspects of neural implants from a technology assessment perspective. Technology assessment (TA) aims at providing knowledge about impacts and consequences of (new) technologies as well as about political and societal ways of dealing with them. It reflects about implementation conditions of technology and potential technology conflicts. Over the

  10. Neural control of cursor trajectory and click by a human with tetraplegia 1000 days after implant of an intracortical microelectrode array

    NASA Astrophysics Data System (ADS)

    Simeral, J. D.; Kim, S.-P.; Black, M. J.; Donoghue, J. P.; Hochberg, L. R.

    2011-04-01

    The ongoing pilot clinical trial of the BrainGate neural interface system aims in part to assess the feasibility of using neural activity obtained from a small-scale, chronically implanted, intracortical microelectrode array to provide control signals for a neural prosthesis system. Critical questions include how long implanted microelectrodes will record useful neural signals, how reliably those signals can be acquired and decoded, and how effectively they can be used to control various assistive technologies such as computers and robotic assistive devices, or to enable functional electrical stimulation of paralyzed muscles. Here we examined these questions by assessing neural cursor control and BrainGate system characteristics on five consecutive days 1000 days after implant of a 4 × 4 mm array of 100 microelectrodes in the motor cortex of a human with longstanding tetraplegia subsequent to a brainstem stroke. On each of five prospectively-selected days we performed time-amplitude sorting of neuronal spiking activity, trained a population-based Kalman velocity decoding filter combined with a linear discriminant click state classifier, and then assessed closed-loop point-and-click cursor control. The participant performed both an eight-target center-out task and a random target Fitts metric task which was adapted from a human-computer interaction ISO standard used to quantify performance of computer input devices. The neural interface system was further characterized by daily measurement of electrode impedances, unit waveforms and local field potentials. Across the five days, spiking signals were obtained from 41 of 96 electrodes and were successfully decoded to provide neural cursor point-and-click control with a mean task performance of 91.3% ± 0.1% (mean ± s.d.) correct target acquisition. Results across five consecutive days demonstrate that a neural interface system based on an intracortical microelectrode array can provide repeatable, accurate point

  11. Neural control of cursor trajectory and click by a human with tetraplegia 1000 days after implant of an intracortical microelectrode array

    PubMed Central

    Simeral, J D; Kim, S-P; Black, M J; Donoghue, J P; Hochberg, L R

    2013-01-01

    The ongoing pilot clinical trial of the BrainGate neural interface system aims in part to assess the feasibility of using neural activity obtained from a small-scale, chronically implanted, intracortical microelectrode array to provide control signals for a neural prosthesis system. Critical questions include how long implanted microelectrodes will record useful neural signals, how reliably those signals can be acquired and decoded, and how effectively they can be used to control various assistive technologies such as computers and robotic assistive devices, or to enable functional electrical stimulation of paralyzed muscles. Here we examined these questions by assessing neural cursor control and BrainGate system characteristics on five consecutive days 1000 days after implant of a 4 × 4 mm array of 100 microelectrodes in the motor cortex of a human with longstanding tetraplegia subsequent to a brainstem stroke. On each of five prospectively-selected days we performed time-amplitude sorting of neuronal spiking activity, trained a population-based Kalman velocity decoding filter combined with a linear discriminant click state classifier, and then assessed closed-loop point-and-click cursor control. The participant performed both an eight-target center-out task and a random target Fitts metric task which was adapted from a human-computer interaction ISO standard used to quantify performance of computer input devices. The neural interface system was further characterized by daily measurement of electrode impedances, unit waveforms and local field potentials. Across the five days, spiking signals were obtained from 41 of 96 electrodes and were successfully decoded to provide neural cursor point-and-click control with a mean task performance of 91.3% ± 0.1% (mean ± s.d.) correct target acquisition. Results across five consecutive days demonstrate that a neural interface system based on an intracortical microelectrode array can provide repeatable, accurate point

  12. An Implantable Wireless Neural Interface System for Simultaneous Recording and Stimulation of Peripheral Nerve with a Single Cuff Electrode.

    PubMed

    Shon, Ahnsei; Chu, Jun-Uk; Jung, Jiuk; Kim, Hyungmin; Youn, Inchan

    2017-12-21

    Recently, implantable devices have become widely used in neural prostheses because they eliminate endemic drawbacks of conventional percutaneous neural interface systems. However, there are still several issues to be considered: low-efficiency wireless power transmission; wireless data communication over restricted operating distance with high power consumption; and limited functionality, working either as a neural signal recorder or as a stimulator. To overcome these issues, we suggest a novel implantable wireless neural interface system for simultaneous neural signal recording and stimulation using a single cuff electrode. By using widely available commercial off-the-shelf (COTS) components, an easily reconfigurable implantable wireless neural interface system was implemented into one compact module. The implantable device includes a wireless power consortium (WPC)-compliant power transmission circuit, a medical implant communication service (MICS)-band-based radio link and a cuff-electrode path controller for simultaneous neural signal recording and stimulation. During in vivo experiments with rabbit models, the implantable device successfully recorded and stimulated the tibial and peroneal nerves while communicating with the external device. The proposed system can be modified for various implantable medical devices, especially such as closed-loop control based implantable neural prostheses requiring neural signal recording and stimulation at the same time.

  13. An Implantable Wireless Neural Interface System for Simultaneous Recording and Stimulation of Peripheral Nerve with a Single Cuff Electrode

    PubMed Central

    Shon, Ahnsei; Chu, Jun-Uk; Jung, Jiuk; Youn, Inchan

    2017-01-01

    Recently, implantable devices have become widely used in neural prostheses because they eliminate endemic drawbacks of conventional percutaneous neural interface systems. However, there are still several issues to be considered: low-efficiency wireless power transmission; wireless data communication over restricted operating distance with high power consumption; and limited functionality, working either as a neural signal recorder or as a stimulator. To overcome these issues, we suggest a novel implantable wireless neural interface system for simultaneous neural signal recording and stimulation using a single cuff electrode. By using widely available commercial off-the-shelf (COTS) components, an easily reconfigurable implantable wireless neural interface system was implemented into one compact module. The implantable device includes a wireless power consortium (WPC)-compliant power transmission circuit, a medical implant communication service (MICS)-band-based radio link and a cuff-electrode path controller for simultaneous neural signal recording and stimulation. During in vivo experiments with rabbit models, the implantable device successfully recorded and stimulated the tibial and peroneal nerves while communicating with the external device. The proposed system can be modified for various implantable medical devices, especially such as closed-loop control based implantable neural prostheses requiring neural signal recording and stimulation at the same time. PMID:29267230

  14. In vitro and in vivo analysis and characterization of engineered spinal neural implants (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Shor, Erez; Shoham, Shy; Levenberg, Shulamit

    2016-03-01

    Spinal cord injury is a devastating medical condition. Recent developments in pre-clinical and clinical research have started to yield neural implants inducing functional recovery after spinal cord transection injury. However, the functional performance of the transplants was assessed using histology and behavioral experiments which are unable to study cell dynamics and the therapeutic response. Here, we use neurophotonic tools and optogenetic probes to investigate cellular level morphology and activity characteristics of neural implants over time at the cellular level. These methods were used in-vitro and in-vivo, in a mouse spinal cord injury implant model. Following previous attempts to induce recovery after spinal cord injury, we engineered a pre-vascularized implant to obtain better functional performance. To image network activity of a construct implanted in a mouse spinal cord, we transfected the implant to express GCaMP6 calcium activity indicators and implanted these constructs under a spinal cord chamber enabling 2-photon chronic in vivo neural activity imaging. Activity and morphology analysis image processing software was developed to automatically quantify the behavior of the neural and vascular networks. Our experimental results and analyses demonstrate that vascularized and non-vascularized constructs exhibit very different morphologic and activity patterns at the cellular level. This work enables further optimization of neural implants and also provides valuable tools for continuous cellular level monitoring and evaluation of transplants designed for various neurodegenerative disease models.

  15. Developing Implantable Neuroprosthetics: a New Model in Pig

    PubMed Central

    Yin, Ming; Aceros, Juan; Agha, Naubahar; Minxha, Juri; Komar, Jacob; Patterson, William; Bull, Christopher; Nurmikko, Arto

    2014-01-01

    A new model has been established in the domestic pig for neural prosthetic device development and testing. To this end, we report on a complete neural prosthetic developmental system using a wireless sensor as the implant, a pig as the animal model, and a novel data acquisition paradigm for actuator control. A new type of stereotactic frame with clinically-inspired fixations pins that place the pig brain in standard surgical plane was developed and tested with success during the implantation of the microsystem. The microsystem implanted was an ultralow power (12.5mW) 16-channel intracortical/epicranial device transmitting broadband (40kS/s) data over a wireless infrared telemetric link. Pigs were implanted and neural data was collected over a period of 5 weeks, clearly showing single unit spiking activity. PMID:22254977

  16. Developing implantable neuroprosthetics: a new model in pig.

    PubMed

    Borton, David; Yin, Ming; Aceros, Juan; Agha, Naubahar; Minxha, Juri; Komar, Jacob; Patterson, William; Bull, Christopher; Nurmikko, Arto

    2011-01-01

    A new model has been established in the domestic pig for neural prosthetic device development and testing. To this end, we report on a complete neural prosthetic developmental system using a wireless sensor as the implant, a pig as the animal model, and a novel data acquisition paradigm for actuator control. A new type of stereotactic frame with clinically-inspired fixations pins that place the pig brain in standard surgical plane was developed and tested with success during the implantation of the microsystem. The microsystem implanted was an ultra-low power (12.5 mW) 16-channel intracortical/epicranial device transmitting broadband (40 kS/s) data over a wireless infrared telemetric link. Pigs were implanted and neural data was collected over a period of 5 weeks, clearly showing single unit spiking activity.

  17. Fractal Interfaces for Stimulating and Recording Neural Implants

    NASA Astrophysics Data System (ADS)

    Watterson, William James

    From investigating movement in an insect to deciphering cognition in a human brain to treating Parkinson's disease, hearing loss, or even blindness, electronic implants are an essential tool for understanding the brain and treating neural diseases. Currently, the stimulating and recording resolution of these implants remains low. For instance, they can record all the neuron activity associated with movement in an insect, but are quite far from recording, at an individual neuron resolution, the large volumes of brain tissue associated with cognition. Likewise, there is remarkable success in the cochlear implant restoring hearing due to the relatively simple anatomy of the auditory nerves, but are failing to restore vision to the blind due to poor signal fidelity and transmission in stimulating the more complex anatomy of the visual nerves. The critically important research needed to improve the resolution of these implants is to optimize the neuron-electrode interface. This thesis explores geometrical and material modifications to both stimulating and recording electrodes which can improve the neuron-electrode interface. First, we introduce a fractal electrode geometry which radically improves the restored visual acuity achieved by retinal implants and leads to safe, long-term operation of the implant. Next, we demonstrate excellent neuron survival and neurite outgrowth on carbon nanotube electrodes, thus providing a safe biomaterial which forms a strong connection between the electrode and neurons. Additional preliminary evidence suggests carbon nanotubes patterned into a fractal geometry will provide further benefits in improving the electrode-neuron interface. Finally, we propose a novel implant based off field effect transistor technology which utilizes an interconnecting fractal network of semiconducting carbon nanotubes to record from thousands of neurons simutaneously at an individual neuron resolution. Taken together, these improvements have the potential to

  18. Ultrasmall implantable composite microelectrodes with bioactive surfaces for chronic neural interfaces

    PubMed Central

    Kozai, Takashi D. Yoshida; Langhals, Nicholas B.; Patel, Paras R.; Deng, Xiaopei; Zhang, Huanan; Smith, Karen L.; Lahann, Joerg; Kotov, Nicholas A.; Kipke, Daryl R.

    2012-01-01

    Implantable neural microelectrodes that can record extracellular biopotentials from small, targeted groups of neurons are critical for neuroscience research and emerging clinical applications including brain-controlled prosthetic devices. The crucial material-dependent problem is developing microelectrodes that record neural activity from the same neurons for years with high fidelity and reliability. Here, we report the development of an integrated composite electrode consisting of a carbon-fibre core, a poly(p-xylylene)-based thin-film coating that acts as a dielectric barrier and that is functionalized to control intrinsic biological processes, and a poly(thiophene)-based recording pad. The resulting implants are an order of magnitude smaller than traditional recording electrodes, and more mechanically compliant with brain tissue. They were found to elicit much reduced chronic reactive tissue responses and enabled single-neuron recording in acute and early chronic experiments in rats. This technology, taking advantage of new composites, makes possible highly selective and stealthy neural interface devices towards realizing long-lasting implants. PMID:23142839

  19. System-Level Design of a 64-Channel Low Power Neural Spike Recording Sensor.

    PubMed

    Delgado-Restituto, Manuel; Rodriguez-Perez, Alberto; Darie, Angela; Soto-Sanchez, Cristina; Fernandez-Jover, Eduardo; Rodriguez-Vazquez, Angel

    2017-04-01

    This paper reports an integrated 64-channel neural spike recording sensor, together with all the circuitry to process and configure the channels, process the neural data, transmit via a wireless link the information and receive the required instructions. Neural signals are acquired, filtered, digitized and compressed in the channels. Additionally, each channel implements an auto-calibration algorithm which individually configures the transfer characteristics of the recording site. The system has two transmission modes; in one case the information captured by the channels is sent as uncompressed raw data; in the other, feature vectors extracted from the detected neural spikes are released. Data streams coming from the channels are serialized by the embedded digital processor. Experimental results, including in vivo measurements, show that the power consumption of the complete system is lower than 330 μW.

  20. Cochlear Implant Using Neural Prosthetics

    NASA Astrophysics Data System (ADS)

    Gupta, Shweta; Singh, Shashi kumar; Dubey, Pratik Kumar

    2012-10-01

    This research is based on neural prosthetic device. The oldest and most widely used of these electrical, and often computerized, devices is the cochlear implant, which has provided hearing to thousands of congenitally deaf people in this country. Recently, the use of the cochlear implant is expanding to the elderly, who frequently suffer major hearing loss. More cutting edge are artificial retinas, which are helping dozens of blind people see, and ìsmartî artificial arms and legs that amputees can maneuver by thoughts alone, and that feel more like real limbs.Research, which curiosity led to explore frog legs dancing during thunderstorms, a snail shapedorgan in the inner ear, and how various eye cells react to light, have fostered an understanding of how to ìtalkî to the nervous system. That understanding combined with the miniaturization of electronics and enhanced computer processing has enabled prosthetic devices that often can bridge the gap in nerve signaling that is caused by disease or injury.

  1. Probing the Electrode–Neuron Interface With Focused Cochlear Implant Stimulation

    PubMed Central

    Bierer, Julie Arenberg

    2010-01-01

    Cochlear implants are highly successful neural prostheses for persons with severe or profound hearing loss who gain little benefit from hearing aid amplification. Although implants are capable of providing important spectral and temporal cues for speech perception, performance on speech tests is variable across listeners. Psychophysical measures obtained from individual implant subjects can also be highly variable across implant channels. This review discusses evidence that such variability reflects deviations in the electrode–neuron interface, which refers to an implant channel's ability to effectively stimulate the auditory nerve. It is proposed that focused electrical stimulation is ideally suited to assess channel-to-channel irregularities in the electrode–neuron interface. In implant listeners, it is demonstrated that channels with relatively high thresholds, as measured with the tripolar configuration, exhibit broader psychophysical tuning curves and smaller dynamic ranges than channels with relatively low thresholds. Broader tuning implies that frequency-specific information intended for one population of neurons in the cochlea may activate more distant neurons, and a compressed dynamic range could make it more difficult to resolve intensity-based information, particularly in the presence of competing noise. Degradation of both types of cues would negatively affect speech perception. PMID:20724356

  2. Wireless Microstimulators for Neural Prosthetics

    PubMed Central

    Sahin, Mesut; Pikov, Victor

    2016-01-01

    One of the roadblocks in the field of neural prosthetics is the lack of microelectronic devices for neural stimulation that can last a lifetime in the central nervous system. Wireless multi-electrode arrays are being developed to improve the longevity of implants by eliminating the wire interconnects as well as the chronic tissue reactions due to the tethering forces generated by these wires. An area of research that has not been sufficiently investigated is a simple single-channel passive microstimulator that can collect the stimulus energy that is transmitted wirelessly through the tissue and immediately convert it into the stimulus pulse. For example, many neural prosthetic approaches to intraspinal microstimulation require only a few channels of stimulation. Wired spinal cord implants are not practical for human subjects because of the extensive flexions and rotations that the spinal cord experiences. Thus, intraspinal microstimulation may be a pioneering application that can benefit from submillimetersize floating stimulators. Possible means of energizing such a floating microstimulator, such as optical, acoustic, and electromagnetic waves, are discussed. PMID:21488815

  3. A subcutaneous channeling probe for implanting long leads

    NASA Technical Reports Server (NTRS)

    Lund, G. F.; Simmonds, R. C.; Williams, B. A.

    1977-01-01

    The channeling probe described in the present paper was designed to overcome surgical problems of the type that were encountered when a multichannel radio transmitter had to be implanted in a cow. The probe was made of a flexible but sufficiently stiff 9.5-mm-diam nylon rod, consisting of 46-cm sections for convenience in sterilization and surgical handling. Stainless steel sleaves reinforced the threaded connecting joints. At one end, arrowhead-shaped channeling heads could be attached to produce wide channels for large sensors. The other end was tapered for narrow channels. Postoperative problems were not encountered in the use of this probe in cows, sheep, and dogs.

  4. Power feasibility of implantable digital spike sorting circuits for neural prosthetic systems.

    PubMed

    Zumsteg, Zachary S; Kemere, Caleb; O'Driscoll, Stephen; Santhanam, Gopal; Ahmed, Rizwan E; Shenoy, Krishna V; Meng, Teresa H

    2005-09-01

    A new class of neural prosthetic systems aims to assist disabled patients by translating cortical neural activity into control signals for prosthetic devices. Based on the success of proof-of-concept systems in the laboratory, there is now considerable interest in increasing system performance and creating implantable electronics for use in clinical systems. A critical question that impacts system performance and the overall architecture of these systems is whether it is possible to identify the neural source of each action potential (spike sorting) in real-time and with low power. Low power is essential both for power supply considerations and heat dissipation in the brain. In this paper we report that state-of-the-art spike sorting algorithms are not only feasible using modern complementary metal oxide semiconductor very large scale integration processes, but may represent the best option for extracting large amounts of data in implantable neural prosthetic interfaces.

  5. An Implantable Wireless Neural Interface for Recording Cortical Circuit Dynamics in Moving Primates

    PubMed Central

    Borton, David A.; Yin, Ming; Aceros, Juan; Nurmikko, Arto

    2013-01-01

    Objective Neural interface technology suitable for clinical translation has the potential to significantly impact the lives of amputees, spinal cord injury victims, and those living with severe neuromotor disease. Such systems must be chronically safe, durable, and effective. Approach We have designed and implemented a neural interface microsystem, housed in a compact, subcutaneous, and hermetically sealed titanium enclosure. The implanted device interfaces the brain with a 510k-approved, 100-element silicon-based MEA via a custom hermetic feedthrough design. Full spectrum neural signals were amplified (0.1Hz to 7.8kHz, ×200 gain) and multiplexed by a custom application specific integrated circuit, digitized, and then packaged for transmission. The neural data (24 Mbps) was transmitted by a wireless data link carried on an frequency shift key modulated signal at 3.2GHz and 3.8GHz to a receiver 1 meter away by design as a point-to-point communication link for human clinical use. The system was powered by an embedded medical grade rechargeable Li-ion battery for 7-hour continuous operation between recharge via an inductive transcutaneous wireless power link at 2MHz. Main results Device verification and early validation was performed in both swine and non-human primate freely-moving animal models and showed that the wireless implant was electrically stable, effective in capturing and delivering broadband neural data, and safe for over one year of testing. In addition, we have used the multichannel data from these mobile animal models to demonstrate the ability to decode neural population dynamics associated with motor activity. Significance We have developed an implanted wireless broadband neural recording device evaluated in non-human primate and swine. The use of this new implantable neural interface technology can provide insight on how to advance human neuroprostheses beyond the present early clinical trials. Further, such tools enable mobile patient use, have

  6. An implantable wireless neural interface for recording cortical circuit dynamics in moving primates

    NASA Astrophysics Data System (ADS)

    Borton, David A.; Yin, Ming; Aceros, Juan; Nurmikko, Arto

    2013-04-01

    Objective. Neural interface technology suitable for clinical translation has the potential to significantly impact the lives of amputees, spinal cord injury victims and those living with severe neuromotor disease. Such systems must be chronically safe, durable and effective. Approach. We have designed and implemented a neural interface microsystem, housed in a compact, subcutaneous and hermetically sealed titanium enclosure. The implanted device interfaces the brain with a 510k-approved, 100-element silicon-based microelectrode array via a custom hermetic feedthrough design. Full spectrum neural signals were amplified (0.1 Hz to 7.8 kHz, 200× gain) and multiplexed by a custom application specific integrated circuit, digitized and then packaged for transmission. The neural data (24 Mbps) were transmitted by a wireless data link carried on a frequency-shift-key-modulated signal at 3.2 and 3.8 GHz to a receiver 1 m away by design as a point-to-point communication link for human clinical use. The system was powered by an embedded medical grade rechargeable Li-ion battery for 7 h continuous operation between recharge via an inductive transcutaneous wireless power link at 2 MHz. Main results. Device verification and early validation were performed in both swine and non-human primate freely-moving animal models and showed that the wireless implant was electrically stable, effective in capturing and delivering broadband neural data, and safe for over one year of testing. In addition, we have used the multichannel data from these mobile animal models to demonstrate the ability to decode neural population dynamics associated with motor activity. Significance. We have developed an implanted wireless broadband neural recording device evaluated in non-human primate and swine. The use of this new implantable neural interface technology can provide insight into how to advance human neuroprostheses beyond the present early clinical trials. Further, such tools enable mobile

  7. Channel interaction limits melodic pitch perception in simulated cochlear implants

    PubMed Central

    Crew, Joseph D.; Galvin, John J.; Fu, Qian-Jie

    2012-01-01

    In cochlear implants (CIs), melodic pitch perception is limited by the spectral resolution, which in turn is limited by the number of spectral channels as well as interactions between adjacent channels. This study investigated the effect of channel interaction on melodic contour identification (MCI) in normal-hearing subjects listening to novel 16-channel sinewave vocoders that simulated channel interaction in CI signal processing. MCI performance worsened as the degree of channel interaction increased. Although greater numbers of spectral channels may be beneficial to melodic pitch perception, the present data suggest that it is also important to improve independence among spectral channels. PMID:23145706

  8. Neural Implants, Packaging for Biocompatible Implants, and Improving Fabricated Capacitors

    NASA Astrophysics Data System (ADS)

    Agger, Elizabeth Rose

    We have completed the circuit design and packaging procedure for an NIH-funded neural implant, called a MOTE (Microscale Optoelectronically Transduced Electrode). Neural recording implants for mice have greatly advanced neuroscience, but they are often damaging and limited in their recording location. This project will result in free-floating implants that cause less damage, provide rapid electronic recording, and increase range of recording across the cortex. A low-power silicon IC containing amplification and digitization sub-circuits is powered by a dual-function gallium arsenide photovoltaic and LED. Through thin film deposition, photolithography, and chemical and physical etching, the Molnar Group and the McEuen Group (Applied and Engineering Physics department) will package the IC and LED into a biocompatible implant approximately 100microm3. The IC and LED are complete and we have begun refining this packaging procedure in the Cornell NanoScale Science & Technology Facility. ICs with 3D time-resolved imaging capabilities can image microorganisms and other biological samples given proper packaging. A portable, flat, easily manufactured package would enable scientists to place biological samples on slides directly above the Molnar group's imaging chip. We have developed a packaging procedure using laser cutting, photolithography, epoxies, and metal deposition. Using a flip-chip method, we verified the process by aligning and adhering a sample chip to a holder wafer. In the CNF, we have worked on a long-term metal-insulator-metal (MIM) capacitor characterization project. Former Fellow and continuing CNF user Kwame Amponsah developed the original procedure for the capacitor fabrication, and another former fellow, Jonilyn Longenecker, revised the procedure and began the arduous process of characterization. MIM caps are useful to clean room users as testing devices to verify electronic characteristics of their active circuitry. This project's objective is to

  9. Identifying cochlear implant channels with poor electrode-neuron interface: partial tripolar, single-channel thresholds and psychophysical tuning curves

    PubMed Central

    Bierer, Julie Arenberg; Faulkner, Kathleen F.

    2010-01-01

    Objectives The goal of this study was to evaluate the ability of a threshold measure, made with a restricted electrode configuration, to identify channels exhibiting relatively poor spatial selectivity. With a restricted electrode configuration, channel-to-channel variability in threshold may reflect variations in the interface between the electrodes and auditory neurons (i.e., nerve survival, electrode placement, tissue impedance). These variations in the electrode-neuron interface should also be reflected in psychophysical tuning curve measurements. Specifically, it is hypothesized that high single-channel thresholds obtained with the spatially focused partial tripolar electrode configuration are predictive of wide or tip-shifted psychophysical tuning curves. Design Data were collected from five cochlear implant listeners implanted with the HiRes 90k cochlear implant (Advanced Bionics). Single-channel thresholds and most comfortable listening levels were obtained for stimuli that varied in presumed electrical field size by using the partial tripolar configuration, for which a fraction of current (σ) from a center active electrode returns through two neighboring electrodes and the remainder through a distant indifferent electrode. Forward-masked psychophysical tuning curves were obtained for channels with the highest, lowest, and median tripolar (σ=1 or 0.9) thresholds. The probe channel and level were fixed and presented with either the monopolar (σ=0) or a more focused partial tripolar (σ ≥ 0.55) configuration. The masker channel and level were varied while the configuration was fixed to σ = 0.5. A standard, three-interval, two-alternative forced choice procedure was used for thresholds and masked levels. Results Single-channel threshold and variability in threshold across channels systematically increased as the compensating current, σ, increased and the presumed electrical field became more focused. Across subjects, channels with the highest single-channel

  10. Identifying cochlear implant channels with poor electrode-neuron interface: partial tripolar, single-channel thresholds and psychophysical tuning curves.

    PubMed

    Bierer, Julie Arenberg; Faulkner, Kathleen F

    2010-04-01

    The goal of this study was to evaluate the ability of a threshold measure, made with a restricted electrode configuration, to identify channels exhibiting relatively poor spatial selectivity. With a restricted electrode configuration, channel-to-channel variability in threshold may reflect variations in the interface between the electrodes and auditory neurons (i.e., nerve survival, electrode placement, and tissue impedance). These variations in the electrode-neuron interface should also be reflected in psychophysical tuning curve (PTC) measurements. Specifically, it is hypothesized that high single-channel thresholds obtained with the spatially focused partial tripolar (pTP) electrode configuration are predictive of wide or tip-shifted PTCs. Data were collected from five cochlear implant listeners implanted with the HiRes90k cochlear implant (Advanced Bionics Corp., Sylmar, CA). Single-channel thresholds and most comfortable listening levels were obtained for stimuli that varied in presumed electrical field size by using the pTP configuration for which a fraction of current (sigma) from a center-active electrode returns through two neighboring electrodes and the remainder through a distant indifferent electrode. Forward-masked PTCs were obtained for channels with the highest, lowest, and median tripolar (sigma = 1 or 0.9) thresholds. The probe channel and level were fixed and presented with either the monopolar (sigma = 0) or a more focused pTP (sigma > or = 0.55) configuration. The masker channel and level were varied, whereas the configuration was fixed to sigma = 0.5. A standard, three-interval, two-alternative forced choice procedure was used for thresholds and masked levels. Single-channel threshold and variability in threshold across channels systematically increased as the compensating current, sigma, increased and the presumed electrical field became more focused. Across subjects, channels with the highest single-channel thresholds, when measured with a

  11. Extracellular matrix proteins as temporary coating for thin-film neural implants

    NASA Astrophysics Data System (ADS)

    Ceyssens, Frederik; Deprez, Marjolijn; Turner, Neill; Kil, Dries; van Kuyck, Kris; Welkenhuysen, Marleen; Nuttin, Bart; Badylak, Stephen; Puers, Robert

    2017-02-01

    Objective. This study investigates the suitability of a thin sheet of extracellular matrix (ECM) proteins as a resorbable coating for temporarily reinforcing fragile or ultra-low stiffness thin-film neural implants to be placed on the brain, i.e. microelectrocorticographic (µECOG) implants. Approach. Thin-film polyimide-based electrode arrays were fabricated using lithographic methods. ECM was harvested from porcine tissue by a decellularization method and coated around the arrays. Mechanical tests and an in vivo experiment on rats were conducted, followed by a histological tissue study combined with a statistical equivalence test (confidence interval approach, 0.05 significance level) to compare the test group with an uncoated control group. Main results. After 3 months, no significant damage was found based on GFAP and NeuN staining of the relevant brain areas. Significance. The study shows that ECM sheets are a suitable temporary coating for thin µECOG neural implants.

  12. Comparisons between detection threshold and loudness perception for individual cochlear implant channels

    PubMed Central

    Bierer, Julie Arenberg; Nye, Amberly D

    2014-01-01

    Objective The objective of the present study, performed in cochlear implant listeners, was to examine how the level of current required to detect single-channel electrical pulse trains relates to loudness perception on the same channel. The working hypothesis was that channels with relatively high thresholds, when measured with a focused current pattern, interface poorly to the auditory nerve. For such channels a smaller dynamic range between perceptual threshold and the most comfortable loudness would result, in part, from a greater sensitivity to changes in electrical field spread compared to low-threshold channels. The narrower range of comfortable listening levels may have important implications for speech perception. Design Data were collected from eight, adult cochlear implant listeners implanted with the HiRes90k cochlear implant (Advanced Bionics Corp.). The partial tripolar (pTP) electrode configuration, consisting of one intracochlear active electrode, two flanking electrodes carrying a fraction (σ) of the return current, and an extracochlear ground, was used for stimulation. Single-channel detection thresholds and most comfortable listening levels were acquired using the most focused pTP configuration possible (σ ≥ 0.8) to identify three channels for further testing – those with the highest, median, and lowest thresholds – for each subject. Threshold, equal-loudness contours (at 50% of the monopolar dynamic range), and loudness growth functions were measured for each of these three test channels using various partial tripolar fractions. Results For all test channels, thresholds increased as the electrode configuration became more focused. The rate of increase with the focusing parameter σ was greatest for the high-threshold channel compared to the median- and low-threshold channels. The 50% equal-loudness contours exhibited similar rates of increase in level across test channels and subjects. Additionally, test channels with the highest

  13. Feature extraction using extrema sampling of discrete derivatives for spike sorting in implantable upper-limb neural prostheses.

    PubMed

    Zamani, Majid; Demosthenous, Andreas

    2014-07-01

    Next generation neural interfaces for upper-limb (and other) prostheses aim to develop implantable interfaces for one or more nerves, each interface having many neural signal channels that work reliably in the stump without harming the nerves. To achieve real-time multi-channel processing it is important to integrate spike sorting on-chip to overcome limitations in transmission bandwidth. This requires computationally efficient algorithms for feature extraction and clustering suitable for low-power hardware implementation. This paper describes a new feature extraction method for real-time spike sorting based on extrema analysis (namely positive peaks and negative peaks) of spike shapes and their discrete derivatives at different frequency bands. Employing simulation across different datasets, the accuracy and computational complexity of the proposed method are assessed and compared with other methods. The average classification accuracy of the proposed method in conjunction with online sorting (O-Sort) is 91.6%, outperforming all the other methods tested with the O-Sort clustering algorithm. The proposed method offers a better tradeoff between classification error and computational complexity, making it a particularly strong choice for on-chip spike sorting.

  14. Implantable neurotechnologies: a review of integrated circuit neural amplifiers.

    PubMed

    Ng, Kian Ann; Greenwald, Elliot; Xu, Yong Ping; Thakor, Nitish V

    2016-01-01

    Neural signal recording is critical in modern day neuroscience research and emerging neural prosthesis programs. Neural recording requires the use of precise, low-noise amplifier systems to acquire and condition the weak neural signals that are transduced through electrode interfaces. Neural amplifiers and amplifier-based systems are available commercially or can be designed in-house and fabricated using integrated circuit (IC) technologies, resulting in very large-scale integration or application-specific integrated circuit solutions. IC-based neural amplifiers are now used to acquire untethered/portable neural recordings, as they meet the requirements of a miniaturized form factor, light weight and low power consumption. Furthermore, such miniaturized and low-power IC neural amplifiers are now being used in emerging implantable neural prosthesis technologies. This review focuses on neural amplifier-based devices and is presented in two interrelated parts. First, neural signal recording is reviewed, and practical challenges are highlighted. Current amplifier designs with increased functionality and performance and without penalties in chip size and power are featured. Second, applications of IC-based neural amplifiers in basic science experiments (e.g., cortical studies using animal models), neural prostheses (e.g., brain/nerve machine interfaces) and treatment of neuronal diseases (e.g., DBS for treatment of epilepsy) are highlighted. The review concludes with future outlooks of this technology and important challenges with regard to neural signal amplification.

  15. Implantable neurotechnologies: a review of integrated circuit neural amplifiers

    PubMed Central

    Greenwald, Elliot; Xu, Yong Ping; Thakor, Nitish V.

    2016-01-01

    Neural signal recording is critical in modern day neuroscience research and emerging neural prosthesis programs. Neural recording requires the use of precise, low-noise amplifier systems to acquire and condition the weak neural signals that are transduced through electrode interfaces. Neural amplifiers and amplifier-based systems are available commercially or can be designed in-house and fabricated using integrated circuit (IC) technologies, resulting in very large-scale integration or application-specific integrated circuit solutions. IC-based neural amplifiers are now used to acquire untethered/portable neural recordings, as they meet the requirements of a miniaturized form factor, light weight and low power consumption. Furthermore, such miniaturized and low-power IC neural amplifiers are now being used in emerging implantable neural prosthesis technologies. This review focuses on neural amplifier-based devices and is presented in two interrelated parts. First, neural signal recording is reviewed, and practical challenges are highlighted. Current amplifier designs with increased functionality and performance and without penalties in chip size and power are featured. Second, applications of IC-based neural amplifiers in basic science experiments (e.g., cortical studies using animal models), neural prostheses (e.g., brain/nerve machine interfaces) and treatment of neuronal diseases (e.g., DBS for treatment of epilepsy) are highlighted. The review concludes with future outlooks of this technology and important challenges with regard to neural signal amplification. PMID:26798055

  16. An Implantable Neural Sensing Microsystem with Fiber-Optic Data Transmission and Power Delivery

    PubMed Central

    Park, Sunmee; Borton, David A.; Kang, Mingyu; Nurmikko, Arto V.; Song, Yoon-Kyu

    2013-01-01

    We have developed a prototype cortical neural sensing microsystem for brain implantable neuroengineering applications. Its key feature is that both the transmission of broadband, multichannel neural data and power required for the embedded microelectronics are provided by optical fiber access. The fiber-optic system is aimed at enabling neural recording from rodents and primates by converting cortical signals to a digital stream of infrared light pulses. In the full microsystem whose performance is summarized in this paper, an analog-to-digital converter and a low power digital controller IC have been integrated with a low threshold, semiconductor laser to extract the digitized neural signals optically from the implantable unit. The microsystem also acquires electrical power and synchronization clocks via optical fibers from an external laser by using a highly efficient photovoltaic cell on board. The implantable unit employs a flexible polymer substrate to integrate analog and digital microelectronics and on-chip optoelectronic components, while adapting to the anatomical and physiological constraints of the environment. A low power analog CMOS chip, which includes preamplifier and multiplexing circuitry, is directly flip-chip bonded to the microelectrode array to form the cortical neurosensor device. PMID:23666130

  17. Modulation frequency discrimination with single and multiple channels in cochlear implant users

    PubMed Central

    Galvin, John J.; Oba, Sandy; Başkent, Deniz; Fu, Qian-Jie

    2015-01-01

    Temporal envelope cues convey important speech information for cochlear implant (CI) users. Many studies have explored CI users’ single-channel temporal envelope processing. However, in clinical CI speech processors, temporal envelope information is processed by multiple channels. Previous studies have shown that amplitude modulation frequency discrimination (AMFD) thresholds are better when temporal envelopes are delivered to multiple rather than single channels. In clinical fitting, current levels on single channels must often be reduced to accommodate multi-channel loudness summation. As such, it is unclear whether the multi-channel advantage in AMFD observed in previous studies was due to coherent envelope information distributed across the cochlea or to greater loudness associated with multi-channel stimulation. In this study, single- and multi-channel AMFD thresholds were measured in CI users. Multi-channel component electrodes were either widely or narrowly spaced to vary the degree of overlap between neural populations. The reference amplitude modulation (AM) frequency was 100 Hz, and coherent modulation was applied to all channels. In Experiment 1, single- and multi-channel AMFD thresholds were measured at similar loudness. In this case, current levels on component channels were higher for single- than for multi-channel AM stimuli, and the modulation depth was approximately 100% of the perceptual dynamic range (i.e., between threshold and maximum acceptable loudness). Results showed no significant difference in AMFD thresholds between similarly loud single- and multi-channel modulated stimuli. In Experiment 2, single- and multi-channel AMFD thresholds were compared at substantially different loudness. In this case, current levels on component channels were the same for single-and multi-channel stimuli (“summation-adjusted” current levels) and the same range of modulation (in dB) was applied to the component channels for both single- and multi-channel

  18. Using recurrent neural networks for adaptive communication channel equalization.

    PubMed

    Kechriotis, G; Zervas, E; Manolakos, E S

    1994-01-01

    Nonlinear adaptive filters based on a variety of neural network models have been used successfully for system identification and noise-cancellation in a wide class of applications. An important problem in data communications is that of channel equalization, i.e., the removal of interferences introduced by linear or nonlinear message corrupting mechanisms, so that the originally transmitted symbols can be recovered correctly at the receiver. In this paper we introduce an adaptive recurrent neural network (RNN) based equalizer whose small size and high performance makes it suitable for high-speed channel equalization. We propose RNN based structures for both trained adaptation and blind equalization, and we evaluate their performance via extensive simulations for a variety of signal modulations and communication channel models. It is shown that the RNN equalizers have comparable performance with traditional linear filter based equalizers when the channel interferences are relatively mild, and that they outperform them by several orders of magnitude when either the channel's transfer function has spectral nulls or severe nonlinear distortion is present. In addition, the small-size RNN equalizers, being essentially generalized IIR filters, are shown to outperform multilayer perceptron equalizers of larger computational complexity in linear and nonlinear channel equalization cases.

  19. This Neural Implant is designed to be implanted in the Human Central and Nervous System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    None

    A new class of neural implants being developed at the Livermore Lab are the first clinical quality devices capable of two-way conversations with the human nervous systems. Unlike existing interfaces that only sense or only stimulate, these devices are capable of stimulating and sensing using both electric and chemical signals.

  20. This Neural Implant is designed to be implanted in the Human Central and Nervous System

    ScienceCinema

    None

    2018-06-12

    A new class of neural implants being developed at the Livermore Lab are the first clinical quality devices capable of two-way conversations with the human nervous systems. Unlike existing interfaces that only sense or only stimulate, these devices are capable of stimulating and sensing using both electric and chemical signals.

  1. A speech processing study using an acoustic model of a multiple-channel cochlear implant

    NASA Astrophysics Data System (ADS)

    Xu, Ying

    1998-10-01

    A cochlear implant is an electronic device designed to provide sound information for adults and children who have bilateral profound hearing loss. The task of representing speech signals as electrical stimuli is central to the design and performance of cochlear implants. Studies have shown that the current speech- processing strategies provide significant benefits to cochlear implant users. However, the evaluation and development of speech-processing strategies have been complicated by hardware limitations and large variability in user performance. To alleviate these problems, an acoustic model of a cochlear implant with the SPEAK strategy is implemented in this study, in which a set of acoustic stimuli whose psychophysical characteristics are as close as possible to those produced by a cochlear implant are presented on normal-hearing subjects. To test the effectiveness and feasibility of this acoustic model, a psychophysical experiment was conducted to match the performance of a normal-hearing listener using model- processed signals to that of a cochlear implant user. Good agreement was found between an implanted patient and an age-matched normal-hearing subject in a dynamic signal discrimination experiment, indicating that this acoustic model is a reasonably good approximation of a cochlear implant with the SPEAK strategy. The acoustic model was then used to examine the potential of the SPEAK strategy in terms of its temporal and frequency encoding of speech. It was hypothesized that better temporal and frequency encoding of speech can be accomplished by higher stimulation rates and a larger number of activated channels. Vowel and consonant recognition tests were conducted on normal-hearing subjects using speech tokens processed by the acoustic model, with different combinations of stimulation rate and number of activated channels. The results showed that vowel recognition was best at 600 pps and 8 activated channels, but further increases in stimulation rate and

  2. Speech enhancement based on neural networks improves speech intelligibility in noise for cochlear implant users.

    PubMed

    Goehring, Tobias; Bolner, Federico; Monaghan, Jessica J M; van Dijk, Bas; Zarowski, Andrzej; Bleeck, Stefan

    2017-02-01

    Speech understanding in noisy environments is still one of the major challenges for cochlear implant (CI) users in everyday life. We evaluated a speech enhancement algorithm based on neural networks (NNSE) for improving speech intelligibility in noise for CI users. The algorithm decomposes the noisy speech signal into time-frequency units, extracts a set of auditory-inspired features and feeds them to the neural network to produce an estimation of which frequency channels contain more perceptually important information (higher signal-to-noise ratio, SNR). This estimate is used to attenuate noise-dominated and retain speech-dominated CI channels for electrical stimulation, as in traditional n-of-m CI coding strategies. The proposed algorithm was evaluated by measuring the speech-in-noise performance of 14 CI users using three types of background noise. Two NNSE algorithms were compared: a speaker-dependent algorithm, that was trained on the target speaker used for testing, and a speaker-independent algorithm, that was trained on different speakers. Significant improvements in the intelligibility of speech in stationary and fluctuating noises were found relative to the unprocessed condition for the speaker-dependent algorithm in all noise types and for the speaker-independent algorithm in 2 out of 3 noise types. The NNSE algorithms used noise-specific neural networks that generalized to novel segments of the same noise type and worked over a range of SNRs. The proposed algorithm has the potential to improve the intelligibility of speech in noise for CI users while meeting the requirements of low computational complexity and processing delay for application in CI devices. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  3. The consequences of neural degeneration regarding optimal cochlear implant position in scala tympani: a model approach.

    PubMed

    Briaire, Jeroen J; Frijns, Johan H M

    2006-04-01

    Cochlear implant research endeavors to optimize the spatial selectivity, threshold and dynamic range with the objective of improving the speech perception performance of the implant user. One of the ways to achieve some of these goals is by electrode design. New cochlear implant electrode designs strive to bring the electrode contacts into close proximity to the nerve fibers in the modiolus: this is done by placing the contacts on the medial side of the array and positioning the implant against the medial wall of scala tympani. The question remains whether this is the optimal position for a cochlea with intact neural fibers and, if so, whether it is also true for a cochlea with degenerated neural fibers. In this study a computational model of the implanted human cochlea is used to investigate the optimal position of the array with respect to threshold, dynamic range and spatial selectivity for a cochlea with intact nerve fibers and for degenerated nerve fibers. In addition, the model is used to evaluate the predictive value of eCAP measurements for obtaining peri-operative information on the neural status. The model predicts improved threshold, dynamic range and spatial selectivity for the peri-modiolar position at the basal end of the cochlea, with minimal influence of neural degeneration. At the apical end of the array (1.5 cochlear turns), the dynamic range and the spatial selectivity are limited due to the occurrence of cross-turn stimulation, with the exception of the condition without neural degeneration and with the electrode array along the lateral wall of scala tympani. The eCAP simulations indicate that a large P(0) peak occurs before the N(1)P(1) complex when the fibers are not degenerated. The absence of this peak might be used as an indicator for neural degeneration.

  4. Evaluation of biofouling in stainless microfluidic channels for implantable multilayered dialysis device

    NASA Astrophysics Data System (ADS)

    Ota, Takashi; To, Naoya; Kanno, Yoshihiko; Miki, Norihisa

    2017-06-01

    An implantable artificial kidney can markedly improve the quality of life of renal disease patients. Our group has developed an implantable multilayered dialysis system consisting of microfluidic channels and dialysis membranes. Long-term evaluation is necessary for implant devices where biofouling is a critical factor, culminating in the deterioration of dialysis performance. Our previous work revealed that surface conditions, which depend on the manufacturing process, determine the amount of biofouling, and that electrolytic etching is the most suitable technique for forming a channel wall free of biofouling. In this study, we investigated the electrolytic etching conditions in detail. We conducted in vitro experiments for 7 d and evaluated the adhesion of biomaterials by scanning electron microscopy. The experiments revealed that a surface mirror-finished by electrolytic etching effectively prevents biofouling.

  5. Hall effect mobility for SiC MOSFETs with increasing dose of nitrogen implantation into channel region

    NASA Astrophysics Data System (ADS)

    Noguchi, Munetaka; Iwamatsu, Toshiaki; Amishiro, Hiroyuki; Watanabe, Hiroshi; Kita, Koji; Yamakawa, Satoshi

    2018-04-01

    The Hall effect mobility (μHall) of the Si-face 4H-SiC metal–oxide–semiconductor field effect transistor (MOSFET) with a nitrogen (N)-implanted channel region was investigated by increasing the N dose. The μHall in the channel region was systematically examined regarding channel structures, that is, the surface and buried channels. It was experimentally demonstrated that increasing the N dose results in an improvement in μHall in the channel region due to the formation of the buried channel. However, further increase in N dose was found to decrease the μHall in the channel region, owing to the decrease in the electron mobility in the N-implanted bulk region.

  6. An implanted 8-channel array coil for high-resolution macaque MRI at 3T

    PubMed Central

    Janssens, T.; Keil, B.; Farivar, R.; McNab, J.A.; Polimeni, J. R.; Gerits, A.; Arsenault, J.T.; Wald, L. L.; Vanduffel, W.

    2012-01-01

    An 8-channel receive coil array was constructed and implanted adjacent to the skull in a male rhesus monkey in order to improve the sensitivity of (functional) brain imaging. The permanent implant was part of an acrylic headpost assembly and only the coil element loop wires were implanted. The tuning, matching, and preamplifier circuitry was connected via a removable external assembly. Signal-to-noise ratio (SNR) and noise amplification for parallel imaging were compared to a single-, 4-, and 8-channel external receive-only coil routinely used for macaque fMRI. In vivo measurements showed significantly improved SNR within the brain for the implanted versus the external coils. Within a region-of-interest covering the cerebral cortex, we observed a 5.4-, 3.6-fold, and 3.4-fold increase in SNR compared to the external single-, 4-, and 8-channel coil, respectively. In the center of the brain, the implanted array maintained a 2.4×, 2.5×, and 2.1× higher SNR, respectively compared to the external coils. The array performance was evaluated for anatomical, diffusion tensor and functional brain imaging. This study suggests that a stable implanted phased-array coil can be used in macaque MRI to substantially increase the spatial resolution for anatomical, diffusion tensor, and functional imaging. PMID:22609793

  7. The 128-channel fully differential digital integrated neural recording and stimulation interface.

    PubMed

    Shahrokhi, Farzaneh; Abdelhalim, Karim; Serletis, Demitre; Carlen, Peter L; Genov, Roman

    2010-06-01

    We present a fully differential 128-channel integrated neural interface. It consists of an array of 8 X 16 low-power low-noise signal-recording and generation circuits for electrical neural activity monitoring and stimulation, respectively. The recording channel has two stages of signal amplification and conditioning with and a fully differential 8-b column-parallel successive approximation (SAR) analog-to-digital converter (ADC). The total measured power consumption of each recording channel, including the SAR ADC, is 15.5 ¿W. The measured input-referred noise is 6.08 ¿ Vrms over a 5-kHz bandwidth, resulting in a noise efficiency factor of 5.6. The stimulation channel performs monophasic or biphasic voltage-mode stimulation, with a maximum stimulation current of 5 mA and a quiescent power dissipation of 51.5 ¿W. The design is implemented in 0.35-¿m complementary metal-oxide semiconductor technology with the channel pitch of 200 ¿m for a total die size of 3.4 mm × 2.5 mm and a total power consumption of 9.33 mW. The neural interface was validated in in vitro recording of a low-Mg(2+)/high-K(+) epileptic seizure model in an intact hippocampus of a mouse.

  8. A physiological and behavioral system for hearing restoration with cochlear implants

    PubMed Central

    King, Julia; Shehu, Ina; Roland, J. Thomas; Svirsky, Mario A.

    2016-01-01

    Cochlear implants are neuroprosthetic devices that provide hearing to deaf patients, although outcomes are highly variable even with prolonged training and use. The central auditory system must process cochlear implant signals, but it is unclear how neural circuits adapt—or fail to adapt—to such inputs. The knowledge of these mechanisms is required for development of next-generation neuroprosthetics that interface with existing neural circuits and enable synaptic plasticity to improve perceptual outcomes. Here, we describe a new system for cochlear implant insertion, stimulation, and behavioral training in rats. Animals were first ensured to have significant hearing loss via physiological and behavioral criteria. We developed a surgical approach for multichannel (2- or 8-channel) array insertion, comparable with implantation procedures and depth in humans. Peripheral and cortical responses to stimulation were used to program the implant objectively. Animals fitted with implants learned to use them for an auditory-dependent task that assesses frequency detection and recognition in a background of environmentally and self-generated noise and ceased responding appropriately to sounds when the implant was temporarily inactivated. This physiologically calibrated and behaviorally validated system provides a powerful opportunity to study the neural basis of neuroprosthetic device use and plasticity. PMID:27281743

  9. Crowd counting via region based multi-channel convolution neural network

    NASA Astrophysics Data System (ADS)

    Cao, Xiaoguang; Gao, Siqi; Bai, Xiangzhi

    2017-11-01

    This paper proposed a novel region based multi-channel convolution neural network architecture for crowd counting. In order to effectively solve the perspective distortion in crowd datasets with a great diversity of scales, this work combines the main channel and three branch channels. These channels extract both the global and region features. And the results are used to estimate density map. Moreover, kernels with ladder-shaped sizes are designed across all the branch channels, which generate adaptive region features. Also, branch channels use relatively deep and shallow network to achieve more accurate detector. By using these strategies, the proposed architecture achieves state-of-the-art performance on ShanghaiTech datasets and competitive performance on UCF_CC_50 datasets.

  10. Convolutional Neural Networks for 1-D Many-Channel Data

    DTIC Science & Technology

    Deep convolutional neural networks (CNNs) represent the state of the art in image recognition. The same properties that led to their success in that... crack detection ( 8,000 data points, 72 channels). Though the models predictive ability is limited to fitting the trend , its partial success suggests that...originally written to classify digits in the MNIST database (28 28 pixels, 1 channel), for use on 1-D acoustic data taken from experiments focused on

  11. Neural preservation underlies speech improvement from auditory deprivation in young cochlear implant recipients.

    PubMed

    Feng, Gangyi; Ingvalson, Erin M; Grieco-Calub, Tina M; Roberts, Megan Y; Ryan, Maura E; Birmingham, Patrick; Burrowes, Delilah; Young, Nancy M; Wong, Patrick C M

    2018-01-30

    Although cochlear implantation enables some children to attain age-appropriate speech and language development, communicative delays persist in others, and outcomes are quite variable and difficult to predict, even for children implanted early in life. To understand the neurobiological basis of this variability, we used presurgical neural morphological data obtained from MRI of individual pediatric cochlear implant (CI) candidates implanted younger than 3.5 years to predict variability of their speech-perception improvement after surgery. We first compared neuroanatomical density and spatial pattern similarity of CI candidates to that of age-matched children with normal hearing, which allowed us to detail neuroanatomical networks that were either affected or unaffected by auditory deprivation. This information enables us to build machine-learning models to predict the individual children's speech development following CI. We found that regions of the brain that were unaffected by auditory deprivation, in particular the auditory association and cognitive brain regions, produced the highest accuracy, specificity, and sensitivity in patient classification and the most precise prediction results. These findings suggest that brain areas unaffected by auditory deprivation are critical to developing closer to typical speech outcomes. Moreover, the findings suggest that determination of the type of neural reorganization caused by auditory deprivation before implantation is valuable for predicting post-CI language outcomes for young children.

  12. Threshold and channel interaction in cochlear implant users: evaluation of the tripolar electrode configuration.

    PubMed

    Bierer, Julie Arenberg

    2007-03-01

    The efficacy of cochlear implants is limited by spatial and temporal interactions among channels. This study explores the spatially restricted tripolar electrode configuration and compares it to bipolar and monopolar stimulation. Measures of threshold and channel interaction were obtained from nine subjects implanted with the Clarion HiFocus-I electrode array. Stimuli were biphasic pulses delivered at 1020 pulses/s. Threshold increased from monopolar to bipolar to tripolar stimulation and was most variable across channels with the tripolar configuration. Channel interaction, quantified by the shift in threshold between single- and two-channel stimulation, occurred for all three configurations but was largest for the monopolar and simultaneous conditions. The threshold shifts with simultaneous tripolar stimulation were slightly smaller than with bipolar and were not as strongly affected by the timing of the two channel stimulation as was monopolar. The subjects' performances on clinical speech tests were correlated with channel-to-channel variability in tripolar threshold, such that greater variability was related to poorer performance. The data suggest that tripolar channels with high thresholds may reveal cochlear regions of low neuron survival or poor electrode placement.

  13. Residual neural processing of musical sound features in adult cochlear implant users.

    PubMed

    Timm, Lydia; Vuust, Peter; Brattico, Elvira; Agrawal, Deepashri; Debener, Stefan; Büchner, Andreas; Dengler, Reinhard; Wittfoth, Matthias

    2014-01-01

    Auditory processing in general and music perception in particular are hampered in adult cochlear implant (CI) users. To examine the residual music perception skills and their underlying neural correlates in CI users implanted in adolescence or adulthood, we conducted an electrophysiological and behavioral study comparing adult CI users with normal-hearing age-matched controls (NH controls). We used a newly developed musical multi-feature paradigm, which makes it possible to test automatic auditory discrimination of six different types of sound feature changes inserted within a musical enriched setting lasting only 20 min. The presentation of stimuli did not require the participants' attention, allowing the study of the early automatic stage of feature processing in the auditory cortex. For the CI users, we obtained mismatch negativity (MMN) brain responses to five feature changes but not to changes of rhythm, whereas we obtained MMNs for all the feature changes in the NH controls. Furthermore, the MMNs to deviants of pitch of CI users were reduced in amplitude and later than those of NH controls for changes of pitch and guitar timber. No other group differences in MMN parameters were found to changes in intensity and saxophone timber. Furthermore, the MMNs in CI users reflected the behavioral scores from a respective discrimination task and were correlated with patients' age and speech intelligibility. Our results suggest that even though CI users are not performing at the same level as NH controls in neural discrimination of pitch-based features, they do possess potential neural abilities for music processing. However, CI users showed a disrupted ability to automatically discriminate rhythmic changes compared with controls. The current behavioral and MMN findings highlight the residual neural skills for music processing even in CI users who have been implanted in adolescence or adulthood. -Automatic brain responses to musical feature changes reflect the

  14. Residual Neural Processing of Musical Sound Features in Adult Cochlear Implant Users

    PubMed Central

    Timm, Lydia; Vuust, Peter; Brattico, Elvira; Agrawal, Deepashri; Debener, Stefan; Büchner, Andreas; Dengler, Reinhard; Wittfoth, Matthias

    2014-01-01

    Auditory processing in general and music perception in particular are hampered in adult cochlear implant (CI) users. To examine the residual music perception skills and their underlying neural correlates in CI users implanted in adolescence or adulthood, we conducted an electrophysiological and behavioral study comparing adult CI users with normal-hearing age-matched controls (NH controls). We used a newly developed musical multi-feature paradigm, which makes it possible to test automatic auditory discrimination of six different types of sound feature changes inserted within a musical enriched setting lasting only 20 min. The presentation of stimuli did not require the participants’ attention, allowing the study of the early automatic stage of feature processing in the auditory cortex. For the CI users, we obtained mismatch negativity (MMN) brain responses to five feature changes but not to changes of rhythm, whereas we obtained MMNs for all the feature changes in the NH controls. Furthermore, the MMNs to deviants of pitch of CI users were reduced in amplitude and later than those of NH controls for changes of pitch and guitar timber. No other group differences in MMN parameters were found to changes in intensity and saxophone timber. Furthermore, the MMNs in CI users reflected the behavioral scores from a respective discrimination task and were correlated with patients’ age and speech intelligibility. Our results suggest that even though CI users are not performing at the same level as NH controls in neural discrimination of pitch-based features, they do possess potential neural abilities for music processing. However, CI users showed a disrupted ability to automatically discriminate rhythmic changes compared with controls. The current behavioral and MMN findings highlight the residual neural skills for music processing even in CI users who have been implanted in adolescence or adulthood. Highlights: -Automatic brain responses to musical feature changes

  15. Neurobiochemical changes in the vicinity of a nanostructured neural implant

    NASA Astrophysics Data System (ADS)

    Bérces, Zsófia; Tóth, Kinga; Márton, Gergely; Pál, Ildikó; Kováts-Megyesi, Bálint; Fekete, Zoltán; Ulbert, István; Pongrácz, Anita

    2016-10-01

    Neural interface technologies including recording and stimulation electrodes are currently in the early phase of clinical trials aiming to help patients with spinal cord injuries, degenerative disorders, strokes interrupting descending motor pathways, or limb amputations. Their lifetime is of key importance; however, it is limited by the foreign body response of the tissue causing the loss of neurons and a reactive astrogliosis around the implant surface. Improving the biocompatibility of implant surfaces, especially promoting neuronal attachment and regeneration is therefore essential. In our work, bioactive properties of implanted black polySi nanostructured surfaces (520-800 nm long nanopillars with a diameter of 150-200 nm) were investigated and compared to microstructured Si surfaces in eight-week-long in vivo experiments. Glial encapsulation and local neuronal cell loss were characterised using GFAP and NeuN immunostaining respectively, followed by systematic image analysis. Regarding the severity of gliosis, no significant difference was observed in the vicinity of the different implant surfaces, however, the number of surviving neurons close to the nanostructured surface was higher than that of the microstructured ones. Our results imply that the functionality of implanted microelectrodes covered by Si nanopillars may lead to improved long-term recordings.

  16. Implantation of a 16-channel functional electrical stimulation walking system.

    PubMed

    Sharma, M; Marsolais, E B; Polando, G; Triolo, R J; Davis, J A; Bhadra, N; Uhlir, J P

    1998-02-01

    A 16-channel electrical stimulation system was implanted in a 39-year-old patient with T10 paraplegia to restore sit to stand, walking, and exercise functions. System implantation required two surgical sessions. In the first session, the posterior muscle set consisting of bilateral semimembranosus, adductor magnus, and gluteus maximus muscles were exposed and epimysial electrodes sutured at the point of greatest muscle contraction. Closed double helix intramuscular electrodes were implanted in the erector spinae. Two weeks later, epimysial electrodes were attached to the eight anterior muscles consisting of the tibialis anterior, sartorius, tensor fasciae latae, and vastus lateralis with all 16 electrode leads passed to the anterior abdominal wall. The electrodes were connected to two eight-channel stimulators placed in the iliac fossae, and the system was checked by activating the individual muscles. The implanted stimulators received stimulation instructions and power via a radio frequency link to an external control. Stimulation patterns for standing, walking, sitting, and exercise functions were chosen from a preprogrammed menu via a finger key pad. After 3 weeks of restricted patient activity, all electrodes stimulated either the target muscle or had an acceptable spillover pattern. The patient is undergoing a 16-week rehabilitation course of stimulated exercises gradually increasing in intensity. At the conclusion, the goal is to discharge the patient with the system for spontaneous use. Although long term followup is required to determine system reliability, preliminary clinical results indicate that targeted, repeatable, functional muscle contractions in the lower extremity can be achieved with a system consisting of epimysial electrodes.

  17. Implantable liquid metal-based flexible neural microelectrode array and its application in recovering animal locomotion functions

    NASA Astrophysics Data System (ADS)

    Guo, Rui; Liu, Jing

    2017-10-01

    With significant advantages in rapidly restoring the nerve function, electrical stimulation of nervous tissue is a crucial treatment of peripheral nerve injuries leading to common movement disorder. However, the currently available stimulating electrodes generally based on rigid conductive materials would cause a potential mechanical mismatch with soft neural tissues which thus reduces long-term effects of electrical stimulation. Here, we proposed and fabricated a flexible neural microelectrode array system based on the liquid metal GaIn alloy (75.5% Ga and 24.5% In by weight) and via printing approach. Such an alloy with a unique low melting point (10.35 °C) owns excellent electrical conductivity and high compliance, which are beneficial to serve as implantable flexible neural electrodes. The flexible neural microelectrode array embeds four liquid metal electrodes and stretchable interconnects in a PDMS membrane (500 µm in thickness) that possess a lower elastic modulus (1.055 MPa), which is similar to neural tissues with elastic moduli in the 0.1-1.5 MPa range. The electrical experiments indicate that the liquid metal interconnects could sustain over 7000 mechanical stretch cycles with resistance approximately staying at 4 Ω. Over the conceptual experiments on animal sciatic nerve electrical stimulation, the dead bullfrog implanted with flexible neural microelectrode array could even rhythmically contract and move its lower limbs under the electrical stimulations from the implant. This demonstrates a highly efficient way for quickly recovering biological nerve functions. Further, the good biocompatibility of the liquid metal material was justified via a series of biological experiments. This liquid metal modality for neural stimulation is expected to play important roles as biologic electrodes to overcome the fundamental mismatch in mechanics between biological tissues and electronic devices in the coming time.

  18. Studies of implanted iron in silicon by channeling and Rutherford backscattering

    NASA Technical Reports Server (NTRS)

    Wang, P. W.; Cheng, H. S.; Gibson, W. M.; Corbett, J. W.

    1986-01-01

    Different amounts of 100-keV iron ions have been implanted into high-resistivity p-type FZ-silicon samples. The implantation damage, recovery of damage during various annealing periods and temperatures, movement of iron atoms under annealing and oxidation, and the kinds of defects created after implantation, annealing, or oxidation are all investigated by channeling and backscattering measurements. It is found that the critical fluence of 100-keV iron implanted into silicon at room temperature is about 2.5 x 10 to the 14th Fe/sq cm, and that iron atoms are gettered by silicon oxidation. In this supersaturated region, iron atoms diffuse slightly towards bulk silicon during high-temperature annealing (greater than or equal to 1100 C) but not at all during low-temperature annealing (less than or equal to 1000 C) in dry nitrogen ambient.

  19. Antibacterial, anti-inflammatory and neuroprotective layer-by-layer coatings for neural implants.

    PubMed

    Zhang, Zhiling; Nong, Jia; Zhong, Yinghui

    2015-08-01

    Infection, inflammation, and neuronal loss are common issues that seriously affect the functionality and longevity of chronically implanted neural prostheses. Minocycline hydrochloride (MH) is a broad-spectrum antibiotic and effective anti-inflammatory drug that also exhibits potent neuroprotective activities. In this study, we investigated the development of biocompatible thin film coatings capable of sustained release of MH for improving the long term performance of implanted neural electrodes. We developed a novel magnesium binding-mediated drug delivery mechanism for controlled and sustained release of MH from an ultrathin hydrophilic layer-by-layer (LbL) coating and characterized the parameters that control MH loading and release. The anti-biofilm, anti-inflammatory and neuroprotective potencies of the LbL coating and released MH were also examined. Sustained release of physiologically relevant amount of MH for 46 days was achieved from the Mg(2+)-based LbL coating at a thickness of 1.25 μm. In addition, MH release from the LbL coating is pH-sensitive. The coating and released MH demonstrated strong anti-biofilm, anti-inflammatory, and neuroprotective potencies. This study reports, for the first time, the development of a bioactive coating that can target infection, inflammation, and neuroprotection simultaneously, which may facilitate the translation of neural interfaces to clinical applications.

  20. A review on mechanical considerations for chronically-implanted neural probes

    NASA Astrophysics Data System (ADS)

    Lecomte, Aziliz; Descamps, Emeline; Bergaud, Christian

    2018-06-01

    This review intends to present a comprehensive analysis of the mechanical considerations for chronically-implanted neural probes. Failure of neural electrical recordings or stimulation over time has shown to arise from foreign body reaction and device material stability. It seems that devices that match most closely with the mechanical properties of the brain would be more likely to reduce the mechanical stress at the probe/tissue interface, thus improving body acceptance. The use of low Young’s modulus polymers instead of hard substrates is one way to enhance this mechanical mimetism, though compliance can be achieved through a variety of means. The reduction of probe width and thickness in comparison to a designated length, the use of soft hydrogel coatings and the release in device tethering to the skull, can also improve device compliance. Paradoxically, the more compliant the device, the more likely it will fail during the insertion process in the brain. Strategies have multiplied this past decade to offer partial or temporary stiffness to the device to overcome this buckling effect. A detailed description of the probe insertion mechanisms is provided to analyze potential sources of implantation failure and the need for a mechanically-enhancing structure. This leads us to present an overview of the strategies that have been put in place over the last ten years to overcome buckling issues. Particularly, great emphasis is put on bioresorbable polymers and their assessment for neural applications. Finally, a discussion is provided on some of the key features for the design of mechanically-reliable, polymer-based next generation of chronic neuroprosthetic devices.

  1. Use of Neural Response Telemetry for Pediatric Cochlear Implants: Current Practice.

    PubMed

    Almosnino, Galit; Anne, Samantha; Schwartz, Seth R

    2018-06-01

    Evaluate usage trends of neural response telemetry (NRT) in cochlear implant centers across the nation and assess reported benefits of intraoperative NRT for pediatric cochlear implant recipients. Survey. All US cochlear implant centers (n = 110). A 15-question multiple-choice survey was distributed electronically to all centers. The survey captured demographic information of all centers, practice patterns surrounding the use of NRT, and the extent to which intraoperative NRT is of benefit. Thirty-two invited participants (29%) completed the survey. A majority of participants reported practicing in an academic center (66%), followed by a hospital setting (19%) and private practice (16%). Seventy-two percent of survey participants reported using NRT for pediatric cochlear implant recipients. Sixty-three percent felt it improved the ability to program at initial activation, and 50% of participants felt that NRT improves satisfaction at initial activation. This study suggests that a majority of surgeons use intraoperative NRT for pediatric cochlear implantation as an additional measure to ensure appropriate electrode placement and improve device activation. Larger studies are needed to better establish the relationship between intraoperative NRT and postoperative outcomes and justify the additional costs associated with intraoperative NRT.

  2. Neural interface methods and apparatus to provide artificial sensory capabilities to a subject

    DOEpatents

    Buerger, Stephen P.; Olsson, III, Roy H.; Wojciechowski, Kenneth E.; Novick, David K.; Kholwadwala, Deepesh K.

    2017-01-24

    Embodiments of neural interfaces according to the present invention comprise sensor modules for sensing environmental attributes beyond the natural sensory capability of a subject, and communicating the attributes wirelessly to an external (ex-vivo) portable module attached to the subject. The ex-vivo module encodes and communicates the attributes via a transcutaneous inductively coupled link to an internal (in-vivo) module implanted within the subject. The in-vivo module converts the attribute information into electrical neural stimuli that are delivered to a peripheral nerve bundle within the subject, via an implanted electrode. Methods and apparatus according to the invention incorporate implantable batteries to power the in-vivo module allowing for transcutaneous bidirectional communication of low voltage (e.g. on the order of 5 volts) encoded signals as stimuli commands and neural responses, in a robust, low-error rate, communication channel with minimal effects to the subjects' skin.

  3. Advances in Cochlear Implant Telemetry: Evoked Neural Responses, Electrical Field Imaging, and Technical Integrity

    PubMed Central

    Mens, Lucas H. M.

    2007-01-01

    During the last decade, cochlear implantation has evolved into a well-established treatment of deafness, predominantly because of many improvements in speech processing and the controlled excitation of the auditory nerve. Cochlear implants now also feature telemetry, which is highly useful to monitor the proper functioning of the implanted electronics and electrode contacts. Telemetry can also support the clinical management in young children and difficult cases where neural unresponsiveness is suspected. This article will review recent advances in the telemetry of the electrically evoked compound action potential that have made these measurements simple and routine procedures in most cases. The distribution of the electrical stimulus itself sampled by “electrical field imaging” reveals general patterns of current flow in the normal cochlea and gross abnormalities in individual patients; models have been developed to derive more subtle insights from an individual electrical field imaging. Finally, some thoughts are given to the extended application of telemetry, for example, in monitoring the neural responses or in combination with other treatments of the deaf ear. PMID:17709572

  4. Evoked EMG-based torque prediction under muscle fatigue in implanted neural stimulation

    NASA Astrophysics Data System (ADS)

    Hayashibe, Mitsuhiro; Zhang, Qin; Guiraud, David; Fattal, Charles

    2011-10-01

    In patients with complete spinal cord injury, fatigue occurs rapidly and there is no proprioceptive feedback regarding the current muscle condition. Therefore, it is essential to monitor the muscle state and assess the expected muscle response to improve the current FES system toward adaptive force/torque control in the presence of muscle fatigue. Our team implanted neural and epimysial electrodes in a complete paraplegic patient in 1999. We carried out a case study, in the specific case of implanted stimulation, in order to verify the corresponding torque prediction based on stimulus evoked EMG (eEMG) when muscle fatigue is occurring during electrical stimulation. Indeed, in implanted stimulation, the relationship between stimulation parameters and output torques is more stable than external stimulation in which the electrode location strongly affects the quality of the recruitment. Thus, the assumption that changes in the stimulation-torque relationship would be mainly due to muscle fatigue can be made reasonably. The eEMG was proved to be correlated to the generated torque during the continuous stimulation while the frequency of eEMG also decreased during fatigue. The median frequency showed a similar variation trend to the mean absolute value of eEMG. Torque prediction during fatigue-inducing tests was performed based on eEMG in model cross-validation where the model was identified using recruitment test data. The torque prediction, apart from the potentiation period, showed acceptable tracking performances that would enable us to perform adaptive closed-loop control through implanted neural stimulation in the future.

  5. Radiation damage in Tb-implanted CaF 2 observed by channeling and luminescence measurements

    NASA Astrophysics Data System (ADS)

    Aono, K.; Kumagai, M.; Iwaki, M.; Aoyagi, Y.; Namba, S.

    1993-06-01

    The effects of 100 keV Tb ion implantation in CaF 2 single crystals have been investigated using Rutherford backscattering/channeling technique and luminescence spectra during ion implantation, depending on ion doses. Terbium ions were implanted into (111)-cut CaF 2 single crystals in random directions with doses ranging from 1 × 10 13 to 1 × 10 17 Tb +/cm 2 at -100°C, 25°C and 100°C. The luminescence signals were measured by 100 keV Ar ion beam irradiation at room temperature to Tb-implanted specimens in order to detect the ionic state of Tb. Two broad emission peaks (near 380 and 545 nm) in visible regions were observed, originating from Tb 3+ in CaF 2. The same luminescence was also observed even during Tb implantation to CaF 2. The luminescence near 380 nm is identified as an emission of 5D 3→ 7F 6 and that near 545 nm is 5D 4→ 7F 5. The emission peak intensities depend on ion dose. Channeling measurements suggest that most of the Tb atoms occupy substitutional lattice sites. Intensities of luminescence and Tb depth profiles depend on the target temperature. In conclusion, implanted Tb atoms occupy Ca lattice sites and emit green luminescence light.

  6. Concurrent electrophysiology and TPM/OCT imaging of long-term implanted electrodes (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Gao, Yu-Rong; Ye, Meijun; Welle, Cristin G.

    2017-02-01

    Microelectrodes implanted in the brain cause mechanical damage to the tissue that mediate neuroinflammation and eventual encapsulation by microglia and astrocytes. Electrophysiological signals recorded from implants used in brain-computer interfaces (BCI) degrade over time, limiting their usefulness, but the precise causes and progression are not fully understood. We are investigating the dynamics of brain morphological changes and neuroinflammation with a multimodal approach to better understand the potential causes of implant failure. We performed weekly optical coherence tomography (OCT)-guided two-photon microscopy (TPM) in the region around microelectrodes inserted under a cranial window concurrent with electrophysiological recordings. Transgenic mouse cohorts studied include Thy1-YFP, Cx3cr1, and GFAP-GFP to image neurons, microglia, and astrocytes, respectively. Single-shank, 16-channel, Michigan-style microelectrodes were inserted under the window at a 15-20° angle with an insertion depth up to cortical layer 5. Single-unit and local field potential (LFP) recordings were collected for 15 minutes while the animals moved freely in their home cages. Cellular and vascular morphology were monitored using TPM and OCT at timepoints matched to the recordings. In preliminary data, we observed a decay of neural firing rates in most of the channels after implantation. The relationship between electrophysiological measures (e.g., neural firing rate, LFP power) and neural/vascular morphological measurements (e.g., cell density, glial migration, blood flow changes) will be quantified. The multimodal approach combining electrophysiology and optical imaging provides a broader picture of the multifactorial nature of the response to implanted electrodes. Understanding and accounting for the response may lead to better BCI designs and approaches.

  7. A wireless transmission neural interface system for unconstrained non-human primates.

    PubMed

    Fernandez-Leon, Jose A; Parajuli, Arun; Franklin, Robert; Sorenson, Michael; Felleman, Daniel J; Hansen, Bryan J; Hu, Ming; Dragoi, Valentin

    2015-10-01

    Studying the brain in large animal models in a restrained laboratory rig severely limits our capacity to examine brain circuits in experimental and clinical applications. To overcome these limitations, we developed a high-fidelity 96-channel wireless system to record extracellular spikes and local field potentials from the neocortex. A removable, external case of the wireless device is attached to a titanium pedestal placed in the animal skull. Broadband neural signals are amplified, multiplexed, and continuously transmitted as TCP/IP data at a sustained rate of 24 Mbps. A Xilinx Spartan 6 FPGA assembles the digital signals into serial data frames for transmission at 20 kHz though an 802.11n wireless data link on a frequency-shift key-modulated signal at 5.7-5.8 GHz to a receiver up to 10 m away. The system is powered by two CR123A, 3 V batteries for 2 h of operation. We implanted a multi-electrode array in visual area V4 of one anesthetized monkey (Macaca fascicularis) and in the dorsolateral prefrontal cortex (dlPFC) of a freely moving monkey (Macaca mulatta). The implanted recording arrays were electrically stable and delivered broadband neural data over a year of testing. For the first time, we compared dlPFC neuronal responses to the same set of stimuli (food reward) in restrained and freely moving conditions. Although we did not find differences in neuronal responses as a function of reward type in the restrained and unrestrained conditions, there were significant differences in correlated activity. This demonstrates that measuring neural responses in freely moving animals can capture phenomena that are absent in the traditional head-fixed paradigm. We implemented a wireless neural interface for multi-electrode recordings in freely moving non-human primates, which can potentially move systems neuroscience to a new direction by allowing one to record neural signals while animals interact with their environment.

  8. A wireless transmission neural interface system for unconstrained non-human primates

    PubMed Central

    Fernandez-Leon, Jose A.; Parajuli, Arun; Franklin, Robert; Sorenson, Michael; Felleman, Daniel J.; Hansen, Bryan J.; Hu, Ming; Dragoi, Valentin

    2018-01-01

    Objective Studying the brain in large animal models in a restrained laboratory rig severely limits our capacity to examine brain circuits in experimental and clinical applications. Approach To overcome these limitations, we developed a high-fidelity 96-channel wireless system to record extracellular spikes and local field potentials from neocortex. A removable, external case of the wireless device is attached to a titanium pedestal placed in the animal skull. Broadband neural signals are amplified, multiplexed, and continuously transmitted as TCP/IP data at a sustained rate of 24 Mbps. A Xilinx Spartan 6 FPGA assembles the digital signals into serial data frames for transmission at 20 kHz though an 802.11n wireless data link on a frequency shift key modulated signal at 5.7-5.8 GHz to a receiver up to 10 m away. The system is powered by two CR123A, 3-V batteries for 2 hours of operation. Main results We implanted a multi-electrode array in visual area V4 of one anesthetized monkey (Macaca fascicularis) and in the dorsolateral prefrontal cortex (dlPFC) of a freely moving monkey (Macaca mulatta). The implanted recording arrays were electrically stable and delivered broadband neural data over a year of testing. For the first time, we compared dlPFC neuronal responses to the same set of stimuli (food reward) in restrained and freely moving conditions. Although we did not find differences in neuronal responses as a function of reward type in the restrained and unrestrained conditions, there were significant differences in correlated activity. This demonstrates that measuring neural responses in freely-moving animals can capture phenomena that are absent in the traditional head-fixed paradigm. Significance We implemented a wireless neural interface for multi-electrode recordings in freely moving non-human primates which can potentially move systems neuroscience to a new direction by allowing to record neural signals while animals interact with their environment. PMID

  9. A wireless transmission neural interface system for unconstrained non-human primates

    NASA Astrophysics Data System (ADS)

    Fernandez-Leon, Jose A.; Parajuli, Arun; Franklin, Robert; Sorenson, Michael; Felleman, Daniel J.; Hansen, Bryan J.; Hu, Ming; Dragoi, Valentin

    2015-10-01

    Objective. Studying the brain in large animal models in a restrained laboratory rig severely limits our capacity to examine brain circuits in experimental and clinical applications. Approach. To overcome these limitations, we developed a high-fidelity 96-channel wireless system to record extracellular spikes and local field potentials from the neocortex. A removable, external case of the wireless device is attached to a titanium pedestal placed in the animal skull. Broadband neural signals are amplified, multiplexed, and continuously transmitted as TCP/IP data at a sustained rate of 24 Mbps. A Xilinx Spartan 6 FPGA assembles the digital signals into serial data frames for transmission at 20 kHz though an 802.11n wireless data link on a frequency-shift key-modulated signal at 5.7-5.8 GHz to a receiver up to 10 m away. The system is powered by two CR123A, 3 V batteries for 2 h of operation. Main results. We implanted a multi-electrode array in visual area V4 of one anesthetized monkey (Macaca fascicularis) and in the dorsolateral prefrontal cortex (dlPFC) of a freely moving monkey (Macaca mulatta). The implanted recording arrays were electrically stable and delivered broadband neural data over a year of testing. For the first time, we compared dlPFC neuronal responses to the same set of stimuli (food reward) in restrained and freely moving conditions. Although we did not find differences in neuronal responses as a function of reward type in the restrained and unrestrained conditions, there were significant differences in correlated activity. This demonstrates that measuring neural responses in freely moving animals can capture phenomena that are absent in the traditional head-fixed paradigm. Significance. We implemented a wireless neural interface for multi-electrode recordings in freely moving non-human primates, which can potentially move systems neuroscience to a new direction by allowing one to record neural signals while animals interact with their environment.

  10. Using Evoked Potentials to Match Interaural Electrode Pairs with Bilateral Cochlear Implants

    PubMed Central

    Delgutte, Bertrand

    2007-01-01

    Bilateral cochlear implantation seeks to restore the advantages of binaural hearing to the profoundly deaf by providing binaural cues normally important for accurate sound localization and speech reception in noise. Psychophysical observations suggest that a key issue for the implementation of a successful binaural prosthesis is the ability to match the cochlear positions of stimulation channels in each ear. We used a cat model of bilateral cochlear implants with eight-electrode arrays implanted in each cochlea to develop and test a noninvasive method based on evoked potentials for matching interaural electrodes. The arrays allowed the cochlear location of stimulation to be independently varied in each ear. The binaural interaction component (BIC) of the electrically evoked auditory brainstem response (EABR) was used as an assay of binaural processing. BIC amplitude peaked for interaural electrode pairs at the same relative cochlear position and dropped with increasing cochlear separation in either direction. To test the hypothesis that BIC amplitude peaks when electrodes from the two sides activate maximally overlapping neural populations, we measured multiunit neural activity along the tonotopic gradient of the inferior colliculus (IC) with 16-channel recording probes and determined the spatial pattern of IC activation for each stimulating electrode. We found that the interaural electrode pairings that produced the best aligned IC activation patterns were also those that yielded maximum BIC amplitude. These results suggest that EABR measurements may provide a method for assigning frequency–channel mappings in bilateral implant recipients, such as pediatric patients, for which psychophysical measures of pitch ranking or binaural fusion are unavailable. PMID:17225976

  11. Using evoked potentials to match interaural electrode pairs with bilateral cochlear implants.

    PubMed

    Smith, Zachary M; Delgutte, Bertrand

    2007-03-01

    Bilateral cochlear implantation seeks to restore the advantages of binaural hearing to the profoundly deaf by providing binaural cues normally important for accurate sound localization and speech reception in noise. Psychophysical observations suggest that a key issue for the implementation of a successful binaural prosthesis is the ability to match the cochlear positions of stimulation channels in each ear. We used a cat model of bilateral cochlear implants with eight-electrode arrays implanted in each cochlea to develop and test a noninvasive method based on evoked potentials for matching interaural electrodes. The arrays allowed the cochlear location of stimulation to be independently varied in each ear. The binaural interaction component (BIC) of the electrically evoked auditory brainstem response (EABR) was used as an assay of binaural processing. BIC amplitude peaked for interaural electrode pairs at the same relative cochlear position and dropped with increasing cochlear separation in either direction. To test the hypothesis that BIC amplitude peaks when electrodes from the two sides activate maximally overlapping neural populations, we measured multiunit neural activity along the tonotopic gradient of the inferior colliculus (IC) with 16-channel recording probes and determined the spatial pattern of IC activation for each stimulating electrode. We found that the interaural electrode pairings that produced the best aligned IC activation patterns were also those that yielded maximum BIC amplitude. These results suggest that EABR measurements may provide a method for assigning frequency-channel mappings in bilateral implant recipients, such as pediatric patients, for which psychophysical measures of pitch ranking or binaural fusion are unavailable.

  12. Implanted neural network potentials: Application to Li-Si alloys

    NASA Astrophysics Data System (ADS)

    Onat, Berk; Cubuk, Ekin D.; Malone, Brad D.; Kaxiras, Efthimios

    2018-03-01

    Modeling the behavior of materials composed of elements with different bonding and electronic structure character for large spatial and temporal scales and over a large compositional range is a challenging problem. Cases in point are amorphous alloys of Si, a prototypical covalent material, and Li, a prototypical metal, which are being considered as anodes for high-energy-density batteries. To address this challenge, we develop a methodology based on neural networks that extends the conventional training approach to incorporate pre-trained parts that capture the character of different components, into the overall network; we refer to this model as the "implanted neural network" method. We show that this approach works well for the Si-Li amorphous alloys for a wide range of compositions, giving good results for key quantities like the diffusion coefficients. The method is readily generalizable to more complicated situations that involve two or more different elements.

  13. Antibacterial, anti-inflammatory and neuroprotective layer-by-layer coatings for neural implants

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiling; Nong, Jia; Zhong, Yinghui

    2015-08-01

    Objective. Infection, inflammation, and neuronal loss are common issues that seriously affect the functionality and longevity of chronically implanted neural prostheses. Minocycline hydrochloride (MH) is a broad-spectrum antibiotic and effective anti-inflammatory drug that also exhibits potent neuroprotective activities. In this study, we investigated the development of biocompatible thin film coatings capable of sustained release of MH for improving the long term performance of implanted neural electrodes. Approach. We developed a novel magnesium binding-mediated drug delivery mechanism for controlled and sustained release of MH from an ultrathin hydrophilic layer-by-layer (LbL) coating and characterized the parameters that control MH loading and release. The anti-biofilm, anti-inflammatory and neuroprotective potencies of the LbL coating and released MH were also examined. Main results. Sustained release of physiologically relevant amount of MH for 46 days was achieved from the Mg2+-based LbL coating at a thickness of 1.25 μm. In addition, MH release from the LbL coating is pH-sensitive. The coating and released MH demonstrated strong anti-biofilm, anti-inflammatory, and neuroprotective potencies. Significance. This study reports, for the first time, the development of a bioactive coating that can target infection, inflammation, and neuroprotection simultaneously, which may facilitate the translation of neural interfaces to clinical applications.

  14. Power feasibility of implantable digital spike-sorting circuits for neural prosthetic systems.

    PubMed

    Zumsteg, Zachary S; Ahmed, Rizwan E; Santhanam, Gopal; Shenoy, Krishna V; Meng, Teresa H

    2004-01-01

    A new class of neural prosthetic systems aims to assist disabled patients by translating cortical neural activity into control signals for prosthetic devices. Based on the success of proof-of-concept systems in the laboratory, there is now considerable interest in increasing system performance and creating implantable electronics for use in clinical systems. A critical question that impacts system performance and the overall architecture of these systems is whether it is possible to identify the neural source of each action potential (spike sorting) in real-time and with low power. Low power is essential both for power supply considerations and heat dissipation in the brain. In this paper we report that several state-of-the-art spike sorting algorithms implemented in modern CMOS VLSI processes are expected to be power realistic.

  15. Investigation of MeV-Cu implantation and channeling effects into porous silicon formation

    NASA Astrophysics Data System (ADS)

    Ahmad, M.; Naddaf, M.

    2011-11-01

    P-type (1 1 1) silicon wafers were implanted by copper ions (2.5 MeV) in channeling and random directions using ion beam accelerator of the Atomic Energy Commission of Syria (AECS). The effect of implantation direction on formation process of porous silicon (PS) using electrochemical etching method has been investigated using scanning electron microscope (SEM) and photoluminescence (PL) techniques. SEM observations revealed that the size, shape and density of the formed pores are highly affected by the direction of beam implantation. This in turn is seen to influence the PL behavior of the PS.

  16. Modeling the effect of channel number and interaction on consonant recognition in a cochlear implant peak-picking strategy.

    PubMed

    Verschuur, Carl

    2009-03-01

    Difficulties in speech recognition experienced by cochlear implant users may be attributed both to information loss caused by signal processing and to information loss associated with the interface between the electrode array and auditory nervous system, including cross-channel interaction. The objective of the work reported here was to attempt to partial out the relative contribution of these different factors to consonant recognition. This was achieved by comparing patterns of consonant feature recognition as a function of channel number and presence/absence of background noise in users of the Nucleus 24 device with normal hearing subjects listening to acoustic models that mimicked processing of that device. Additionally, in the acoustic model experiment, a simulation of cross-channel spread of excitation, or "channel interaction," was varied. Results showed that acoustic model experiments were highly correlated with patterns of performance in better-performing cochlear implant users. Deficits to consonant recognition in this subgroup could be attributed to cochlear implant processing, whereas channel interaction played a much smaller role in determining performance errors. The study also showed that large changes to channel number in the Advanced Combination Encoder signal processing strategy led to no substantial changes in performance.

  17. A three dimensional in vitro glial scar model to investigate the local strain effects from micromotion around neural implants.

    PubMed

    Spencer, Kevin C; Sy, Jay C; Falcón-Banchs, Roberto; Cima, Michael J

    2017-02-28

    Glial scar formation remains a significant barrier to the long term success of neural probes. Micromotion coupled with mechanical mismatch between the probe and tissue is believed to be a key driver of the inflammatory response. In vitro glial scar models present an intermediate step prior to conventional in vivo histology experiments as they enable cell-device interactions to be tested on a shorter timescale, with the ability to conduct broader biochemical assays. No established in vitro models have incorporated methods to assess device performance with respect to mechanical factors. In this study, we describe an in vitro glial scar model that combines high-precision linear actuators to simulate axial micromotion around neural implants with a 3D primary neural cell culture in a collagen gel. Strain field measurements were conducted to visualize the local displacement within the gel in response to micromotion. Primary brain cell cultures were found to be mechanically responsive to micromotion after one week in culture. Astrocytes, as determined by immunohistochemical staining, were found to have significantly increased in cell areas and perimeters in response to micromotion compared to static control wells. These results demonstrate the importance of micromotion when considering the chronic response to neural implants. Going forward, this model provides advantages over existing in vitro models as it will enable critical mechanical design factors of neural implants to be evaluated prior to in vivo testing.

  18. A neural network approach to cloud classification

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan; Weger, Ronald C.; Sengupta, Sailes K.; Welch, Ronald M.

    1990-01-01

    It is shown that, using high-spatial-resolution data, very high cloud classification accuracies can be obtained with a neural network approach. A texture-based neural network classifier using only single-channel visible Landsat MSS imagery achieves an overall cloud identification accuracy of 93 percent. Cirrus can be distinguished from boundary layer cloudiness with an accuracy of 96 percent, without the use of an infrared channel. Stratocumulus is retrieved with an accuracy of 92 percent, cumulus at 90 percent. The use of the neural network does not improve cirrus classification accuracy. Rather, its main effect is in the improved separation between stratocumulus and cumulus cloudiness. While most cloud classification algorithms rely on linear parametric schemes, the present study is based on a nonlinear, nonparametric four-layer neural network approach. A three-layer neural network architecture, the nonparametric K-nearest neighbor approach, and the linear stepwise discriminant analysis procedure are compared. A significant finding is that significantly higher accuracies are attained with the nonparametric approaches using only 20 percent of the database as training data, compared to 67 percent of the database in the linear approach.

  19. Neural stem cell implantation extends life in Niemann-Pick C1 mice.

    PubMed

    Ahmad, Iram; Hunter, Robert E; Flax, Jonathan D; Snyder, Evan Y; Erickson, Robert P

    2007-01-01

    In order to evaluate the phenotypic effects of implanted neural stem cells (NSCs) in the mouse model of Niemann-Pick C (NPC) disease, we injected a well-characterized clone of murine NSCs into the cerebella of neonatal Npc1(-/-) and control mice. The implanted cells survived and were abundant in some regions of the cerebellum. Life span was lengthened in NPC mice with the implanted NSCs. However, the rate of weight gain and subsequent weight loss, resulting from neurodegeneration, was not significantly different from un-injected controls. Ataxia was measured by Rota-Rod performance. The overall rate of decline in time on the Rota-Rod was not significantly slowed down. Thus, in this small group of NPC mice, a single administration in the neonatal period of the NSCs (which were not engineered to over-express the missing gene and not directed into the parenchyma) was only partially therapeutic.

  20. Chronic behavior evaluation of a micro-machined neural implant with optimized design based on an experimentally derived model.

    PubMed

    Andrei, Alexandru; Welkenhuysen, Marleen; Ameye, Lieveke; Nuttin, Bart; Eberle, Wolfgang

    2011-01-01

    Understanding the mechanical interactions between implants and the surrounding tissue is known to have an important role for improving the bio-compatibility of such devices. Using a recently developed model, a particular micro-machined neural implant design aiming the reduction of insertion forces dependence on the insertion speed was optimized. Implantations with 10 and 100 μm/s insertion speeds showed excellent agreement with the predicted behavior. Lesion size, gliosis (GFAP), inflammation (ED1) and neuronal cells density (NeuN) was evaluated after 6 week of chronic implantation showing no insertion speed dependence.

  1. A miniaturized neuroprosthesis suitable for implantation into the brain

    NASA Technical Reports Server (NTRS)

    Mojarradi, Mohammad; Binkley, David; Blalock, Benjamin; Andersen, Richard; Ulshoefer, Norbert; Johnson, Travis; Del Castillo, Linda

    2003-01-01

    This paper presents current research on a miniaturized neuroprosthesis suitable for implantation into the brain. The prosthesis is a heterogeneous integration of a 100-element microelectromechanical system (MEMS) electrode array, front-end complementary metal-oxide-semiconductor (CMOS) integrated circuit for neural signal preamplification, filtering, multiplexing and analog-to-digital conversion, and a second CMOS integrated circuit for wireless transmission of neural data and conditioning of wireless power. The prosthesis is intended for applications where neural signals are processed and decoded to permit the control of artificial or paralyzed limbs. This research, if successful, will allow implantation of the electronics into the brain, or subcutaneously on the skull, and eliminate all external signal and power wiring. The neuroprosthetic system design has strict size and power constraints with each of the front-end preamplifier channels fitting within the 400 x 400-microm pitch of the 100-element MEMS electrode array and power dissipation resulting in less than a 1 degree C temperature rise for the surrounding brain tissue. We describe the measured performance of initial micropower low-noise CMOS preamplifiers for the neuroprosthetic.

  2. Histological evaluation of flexible neural implants; flexibility limit for reducing the tissue response?

    NASA Astrophysics Data System (ADS)

    Lee, Heui Chang; Ejserholm, Fredrik; Gaire, Janak; Currlin, Seth; Schouenborg, Jens; Wallman, Lars; Bengtsson, Martin; Park, Kinam; Otto, Kevin J.

    2017-06-01

    Objective. Flexible neural probes are hypothesized to reduce the chronic foreign body response (FBR) mainly by reducing the strain-stress caused by an interplay between the tethered probe and the brain’s micromotion. However, a large discrepancy of Young’s modulus still exists (3-6 orders of magnitude) between the flexible probes and the brain tissue. This raises the question of whether we need to bridge this gap; would increasing the probe flexibility proportionally reduce the FBR? Approach. Using novel off-stoichiometry thiol-enes-epoxy (OSTE+) polymer probes developed in our previous work, we quantitatively evaluated the FBR to four types of probes with different softness: silicon (~150 GPa), polyimide (1.5 GPa), OSTE+Hard (300 MPa), and OSTE+Soft (6 MPa). Main results. We observed a significant reduction in the fluorescence intensity of biomarkers for activated microglia/macrophages and blood-brain barrier (BBB) leakiness around the three soft polymer probes compared to the silicon probe, both at 4 weeks and 8 weeks post-implantation. However, we did not observe any consistent differences in the biomarkers among the polymer probes. Significance. The results suggest that the mechanical compliance of neural probes can mediate the degree of FBR, but its impact diminishes after a hypothetical threshold level. This infers that resolving the mechanical mismatch alone has a limited effect on improving the lifetime of neural implants.

  3. Evidence of across-channel processing for spectral-ripple discrimination in cochlear implant listeners.

    PubMed

    Won, Jong Ho; Jones, Gary L; Drennan, Ward R; Jameyson, Elyse M; Rubinstein, Jay T

    2011-10-01

    Spectral-ripple discrimination has been used widely for psychoacoustical studies in normal-hearing, hearing-impaired, and cochlear implant listeners. The present study investigated the perceptual mechanism for spectral-ripple discrimination in cochlear implant listeners. The main goal of this study was to determine whether cochlear implant listeners use a local intensity cue or global spectral shape for spectral-ripple discrimination. The effect of electrode separation on spectral-ripple discrimination was also evaluated. Results showed that it is highly unlikely that cochlear implant listeners depend on a local intensity cue for spectral-ripple discrimination. A phenomenological model of spectral-ripple discrimination, as an "ideal observer," showed that a perceptual mechanism based on discrimination of a single intensity difference cannot account for performance of cochlear implant listeners. Spectral modulation depth and electrode separation were found to significantly affect spectral-ripple discrimination. The evidence supports the hypothesis that spectral-ripple discrimination involves integrating information from multiple channels. © 2011 Acoustical Society of America

  4. Coding of sounds in the auditory system and its relevance to signal processing and coding in cochlear implants.

    PubMed

    Moore, Brian C J

    2003-03-01

    To review how the properties of sounds are "coded" in the normal auditory system and to discuss the extent to which cochlear implants can and do represent these codes. Data are taken from published studies of the response of the cochlea and auditory nerve to simple and complex stimuli, in both the normal and the electrically stimulated ear. REVIEW CONTENT: The review describes: 1) the coding in the normal auditory system of overall level (which partly determines perceived loudness), spectral shape (which partly determines perceived timbre and the identity of speech sounds), periodicity (which partly determines pitch), and sound location; 2) the role of the active mechanism in the cochlea, and particularly the fast-acting compression associated with that mechanism; 3) the neural response patterns evoked by cochlear implants; and 4) how the response patterns evoked by implants differ from those observed in the normal auditory system in response to sound. A series of specific issues is then discussed, including: 1) how to compensate for the loss of cochlear compression; 2) the effective number of independent channels in a normal ear and in cochlear implantees; 3) the importance of independence of responses across neurons; 4) the stochastic nature of normal neural responses; 5) the possible role of across-channel coincidence detection; and 6) potential benefits of binaural implantation. Current cochlear implants do not adequately reproduce several aspects of the neural coding of sound in the normal auditory system. Improved electrode arrays and coding systems may lead to improved coding and, it is hoped, to better performance.

  5. Spiking Neural Network Decoder for Brain-Machine Interfaces.

    PubMed

    Dethier, Julie; Gilja, Vikash; Nuyujukian, Paul; Elassaad, Shauki A; Shenoy, Krishna V; Boahen, Kwabena

    2011-01-01

    We used a spiking neural network (SNN) to decode neural data recorded from a 96-electrode array in premotor/motor cortex while a rhesus monkey performed a point-to-point reaching arm movement task. We mapped a Kalman-filter neural prosthetic decode algorithm developed to predict the arm's velocity on to the SNN using the Neural Engineering Framework and simulated it using Nengo , a freely available software package. A 20,000-neuron network matched the standard decoder's prediction to within 0.03% (normalized by maximum arm velocity). A 1,600-neuron version of this network was within 0.27%, and run in real-time on a 3GHz PC. These results demonstrate that a SNN can implement a statistical signal processing algorithm widely used as the decoder in high-performance neural prostheses (Kalman filter), and achieve similar results with just a few thousand neurons. Hardware SNN implementations-neuromorphic chips-may offer power savings, essential for realizing fully-implantable cortically controlled prostheses.

  6. Performance sustaining intracortical neural prostheses

    NASA Astrophysics Data System (ADS)

    Nuyujukian, Paul; Kao, Jonathan C.; Fan, Joline M.; Stavisky, Sergey D.; Ryu, Stephen I.; Shenoy, Krishna V.

    2014-12-01

    Objective. Neural prostheses, or brain-machine interfaces, aim to restore efficient communication and movement ability to those suffering from paralysis. A major challenge these systems face is robust performance, particularly with aging signal sources. The aim in this study was to develop a neural prosthesis that could sustain high performance in spite of signal instability while still minimizing retraining time. Approach. We trained two rhesus macaques implanted with intracortical microelectrode arrays 1-4 years prior to this study to acquire targets with a neurally-controlled cursor. We measured their performance via achieved bitrate (bits per second, bps). This task was repeated over contiguous days to evaluate the sustained performance across time. Main results. We found that in the monkey with a younger (i.e., two year old) implant and better signal quality, a fixed decoder could sustain performance for a month at a rate of 4 bps, the highest achieved communication rate reported to date. This fixed decoder was evaluated across 22 months and experienced a performance decline at a rate of 0.24 bps yr-1. In the monkey with the older (i.e., 3.5 year old) implant and poorer signal quality, a fixed decoder could not sustain performance for more than a few days. Nevertheless, performance in this monkey was maintained for two weeks without requiring additional online retraining time by utilizing prior days’ experimental data. Upon analysis of the changes in channel tuning, we found that this stability appeared partially attributable to the cancelling-out of neural tuning fluctuations when projected to two-dimensional cursor movements. Significance. The findings in this study (1) document the highest-performing communication neural prosthesis in monkeys, (2) confirm and extend prior reports of the stability of fixed decoders, and (3) demonstrate a protocol for system stability under conditions where fixed decoders would otherwise fail. These improvements to decoder

  7. COMMUNICATION: Minocycline increases quality and longevity of chronic neural recordings

    NASA Astrophysics Data System (ADS)

    Rennaker, R. L.; Miller, J.; Tang, H.; Wilson, D. A.

    2007-06-01

    Brain/machine interfaces could potentially be used in the treatment of a host of neurological disorders ranging from paralysis to sensory deficits. Insertion of chronic micro-electrode arrays into neural tissue initiates a host of immunological responses, which typically leads to the formation of a cellular sheath around the implant, resulting in the loss of useful signals. Minocycline has been shown to have neuroprotective and neurorestorative effects in certain neural injury and neurodegenerative disease models. This study examined the effects of minocycline administration on the quality and longevity of chronic multi-channel microwire neural implants 1 week and 1 month post-implantation in auditory cortex. The mean signal-to-noise ratio for the minocycline group stabilized at the end of week 1 and remained above 4.6 throughout the following 3 weeks. The control group signal-to-noise ratio dropped throughout the duration of the study and at the end of 4 weeks was 2.6. Furthermore, 68% of electrodes from the minocycline group showed significant stimulus-driven activity at week 4 compared to 12.5% of electrodes in the control group. There was a significant reduction in the number of activated astrocytes around the implant in minocycline subjects, as well as a reduction in total area occupied by activated astrocytes at 1 and 4 weeks.

  8. On the number of channels needed to classify vowels: Implications for cochlear implants

    NASA Astrophysics Data System (ADS)

    Fourakis, Marios; Hawks, John W.; Davis, Erin

    2005-09-01

    In cochlear implants the incoming signal is analyzed by a bank of filters. Each filter is associated with an electrode to constitute a channel. The present research seeks to determine the number of channels needed for optimal vowel classification. Formant measurements of vowels produced by men and women [Hillenbrand et al., J. Acoust. Soc. Am. 97, 3099-3111 (1995)] were converted to channel assignments. The number of channels varied from 4 to 20 over two frequency ranges (180-4000 and 180-6000 Hz) in equal bark steps. Channel assignments were submitted to linear discriminant analysis (LDA). Classification accuracy increased with the number of channels, ranging from 30% with 4 channels to 98% with 20 channels, both for the female voice. To determine asymptotic performance, LDA classification scores were plotted against the number of channels and fitted with quadratic equations. The number of channels at which no further improvement occurred was determined, averaging 19 across all conditions with little variation. This number of channels seems to resolve the frequency range spanned by the first three formants finely enough to maximize vowel classification. This resolution may not be achieved using six or eight channels as previously proposed. [Work supported by NIH.

  9. Stochastic information transfer from cochlear implant electrodes to auditory nerve fibers

    NASA Astrophysics Data System (ADS)

    Gao, Xiao; Grayden, David B.; McDonnell, Mark D.

    2014-08-01

    Cochlear implants, also called bionic ears, are implanted neural prostheses that can restore lost human hearing function by direct electrical stimulation of auditory nerve fibers. Previously, an information-theoretic framework for numerically estimating the optimal number of electrodes in cochlear implants has been devised. This approach relies on a model of stochastic action potential generation and a discrete memoryless channel model of the interface between the array of electrodes and the auditory nerve fibers. Using these models, the stochastic information transfer from cochlear implant electrodes to auditory nerve fibers is estimated from the mutual information between channel inputs (the locations of electrodes) and channel outputs (the set of electrode-activated nerve fibers). Here we describe a revised model of the channel output in the framework that avoids the side effects caused by an "ambiguity state" in the original model and also makes fewer assumptions about perceptual processing in the brain. A detailed comparison of how different assumptions on fibers and current spread modes impact on the information transfer in the original model and in the revised model is presented. We also mathematically derive an upper bound on the mutual information in the revised model, which becomes tighter as the number of electrodes increases. We found that the revised model leads to a significantly larger maximum mutual information and corresponding number of electrodes compared with the original model and conclude that the assumptions made in this part of the modeling framework are crucial to the model's overall utility.

  10. Speech perception of young children using nucleus 22-channel or CLARION cochlear implants.

    PubMed

    Young, N M; Grohne, K M; Carrasco, V N; Brown, C

    1999-04-01

    This study compares the auditory perceptual skill development of 23 congenitally deaf children who received the Nucleus 22-channel cochlear implant with the SPEAK speech coding strategy, and 20 children who received the CLARION Multi-Strategy Cochlear Implant with the Continuous Interleaved Sampler (CIS) speech coding strategy. All were under 5 years old at implantation. Preimplantation, there were no significant differences between the groups in age, length of hearing aid use, or communication mode. Auditory skills were assessed at 6 months and 12 months after implantation. Postimplantation, the mean scores on all speech perception tests were higher for the Clarion group. These differences were statistically significant for the pattern perception and monosyllable subtests of the Early Speech Perception battery at 6 months, and for the Glendonald Auditory Screening Procedure at 12 months. Multiple regression analysis revealed that device type accounted for the greatest variance in performance after 12 months of implant use. We conclude that children using the CIS strategy implemented in the Clarion implant may develop better auditory perceptual skills during the first year postimplantation than children using the SPEAK strategy with the Nucleus device.

  11. A multichannel integrated circuit for electrical recording of neural activity, with independent channel programmability.

    PubMed

    Mora Lopez, Carolina; Prodanov, Dimiter; Braeken, Dries; Gligorijevic, Ivan; Eberle, Wolfgang; Bartic, Carmen; Puers, Robert; Gielen, Georges

    2012-04-01

    Since a few decades, micro-fabricated neural probes are being used, together with microelectronic interfaces, to get more insight in the activity of neuronal networks. The need for higher temporal and spatial recording resolutions imposes new challenges on the design of integrated neural interfaces with respect to power consumption, data handling and versatility. In this paper, we present an integrated acquisition system for in vitro and in vivo recording of neural activity. The ASIC consists of 16 low-noise, fully-differential input channels with independent programmability of its amplification (from 100 to 6000 V/V) and filtering (1-6000 Hz range) capabilities. Each channel is AC-coupled and implements a fourth-order band-pass filter in order to steeply attenuate out-of-band noise and DC input offsets. The system achieves an input-referred noise density of 37 nV/√Hz, a NEF of 5.1, a CMRR > 60 dB, a THD < 1% and a sampling rate of 30 kS/s per channel, while consuming a maximum of 70 μA per channel from a single 3.3 V. The ASIC was implemented in a 0.35 μm CMOS technology and has a total area of 5.6 × 4.5 mm². The recording system was successfully validated in in vitro and in vivo experiments, achieving simultaneous multichannel recordings of cell activity with satisfactory signal-to-noise ratios.

  12. Acrylic resin guide for locating the abutment screw access channel of cement-retained implant prostheses.

    PubMed

    Ahmed, Ayman; Maroulakos, Georgios; Garaicoa, Jorge

    2016-05-01

    Abutment screw loosening represents a common and challenging technical complication of cement-retained implant prostheses. This article describes the fabrication of a simple and accurate poly(methyl methacrylate) guide for identifying the location and angulation of the abutment screw access channel of a cement-retained implant prosthesis with a loosened abutment screw. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  13. Electrical Neural Stimulation and Simultaneous in Vivo Monitoring with Transparent Graphene Electrode Arrays Implanted in GCaMP6f Mice.

    PubMed

    Park, Dong-Wook; Ness, Jared P; Brodnick, Sarah K; Esquibel, Corinne; Novello, Joseph; Atry, Farid; Baek, Dong-Hyun; Kim, Hyungsoo; Bong, Jihye; Swanson, Kyle I; Suminski, Aaron J; Otto, Kevin J; Pashaie, Ramin; Williams, Justin C; Ma, Zhenqiang

    2018-01-23

    Electrical stimulation using implantable electrodes is widely used to treat various neuronal disorders such as Parkinson's disease and epilepsy and is a widely used research tool in neuroscience studies. However, to date, devices that help better understand the mechanisms of electrical stimulation in neural tissues have been limited to opaque neural electrodes. Imaging spatiotemporal neural responses to electrical stimulation with minimal artifact could allow for various studies that are impossible with existing opaque electrodes. Here, we demonstrate electrical brain stimulation and simultaneous optical monitoring of the underlying neural tissues using carbon-based, fully transparent graphene electrodes implanted in GCaMP6f mice. Fluorescence imaging of neural activity for varying electrical stimulation parameters was conducted with minimal image artifact through transparent graphene electrodes. In addition, full-field imaging of electrical stimulation verified more efficient neural activation with cathode leading stimulation compared to anode leading stimulation. We have characterized the charge density limitation of capacitive four-layer graphene electrodes as 116.07-174.10 μC/cm 2 based on electrochemical impedance spectroscopy, cyclic voltammetry, failure bench testing, and in vivo testing. This study demonstrates the transparent ability of graphene neural electrodes and provides a method to further increase understanding and potentially improve therapeutic electrical stimulation in the central and peripheral nervous systems.

  14. Toward multi-area distributed network of implanted neural interrogators

    NASA Astrophysics Data System (ADS)

    Powell, Marc P.; Hou, Xiaoxiao; Galligan, Craig; Ashe, Jeffrey; Borton, David A.

    2017-08-01

    As we aim to improve our understanding of the brain, it is critical that researchers have simultaneous multi-area, large-scale access to the brain. Information processing in the brain occurs through close and distant coupling of functional sub-domains, as opposed to within isolated single neurons. However, commercially available neural interfaces capable of sensing electrophysiology of single neurons, currently allow access to only a small, mm3 volume of cortical cells, are not scalable to recording from orders of magnitude more neurons, and leverage bulky, skull mounted hardware and cabling sensitive to relative movements of the skull and brain. In this work, we propose a system capable of recording from many individual distributed neural interrogator nodes, untethered from any external electronics. Using an array of epidural inductive coils to wirelessly power the implanted electronics, the system is intended to be agnostic to the surgical placement of any individual node. Here, we demonstrate the ability to transmit nearly 15mW of power with greater than 50% power transfer efficiency, benchtop testing of individual subcircuit system components showing successful digitization of neural signals, and wireless transmission currently supporting a data rate of 3.84Mbps. We leverage a software defined radio based RF receiver to demodulate the data which can be stored in memory for later retrieval. Finally, we introduce a packaging technology capable of isolating active electronics from the surrounding tissue while providing capability for electrical feed-through assemblies for external neural interfacing. We expect, based on the presented preliminary findings, that the system can be integrated into a platform technology for the study of the intricate interactions between cortical domains.

  15. Evidence of across-channel processing for spectral-ripple discrimination in cochlear implant listeners a

    PubMed Central

    Ho Won, Jong; Jones, Gary L.; Drennan, Ward R.; Jameyson, Elyse M.; Rubinstein, Jay T.

    2011-01-01

    Spectral-ripple discrimination has been used widely for psychoacoustical studies in normal-hearing, hearing-impaired, and cochlear implant listeners. The present study investigated the perceptual mechanism for spectral-ripple discrimination in cochlear implant listeners. The main goal of this study was to determine whether cochlear implant listeners use a local intensity cue or global spectral shape for spectral-ripple discrimination. The effect of electrode separation on spectral-ripple discrimination was also evaluated. Results showed that it is highly unlikely that cochlear implant listeners depend on a local intensity cue for spectral-ripple discrimination. A phenomenological model of spectral-ripple discrimination, as an “ideal observer,” showed that a perceptual mechanism based on discrimination of a single intensity difference cannot account for performance of cochlear implant listeners. Spectral modulation depth and electrode separation were found to significantly affect spectral-ripple discrimination. The evidence supports the hypothesis that spectral-ripple discrimination involves integrating information from multiple channels. PMID:21973363

  16. Bone marrow mononuclear cell implantation in myocardial laser channels in the ischemic heart disease surgery. Long-term results

    NASA Astrophysics Data System (ADS)

    Chernyavskiy, Alexander; Fomichev, Alexey; Minin, Stanislav; Nikitin, Nikita

    2017-10-01

    Background: The problem of incomplete myocardial revascularization for diffuse and distal lesions of the myocardium is still relevant. We assessed the clinical and instrumental long-term results of autologous bone marrow cell (BMC) implantation in laser channels in ischemic heart disease with diffuse and distal coronary disease. 35 coronary heart disease (CHD) patients with diffuse and distal coronary disease during coronary artery bypass grafting (CABG) underwent BMC implantation in laser channels. The control group consisted of 29 patients. All patients in this group underwent only CABG. Clinical and instrumental assessment of the method's effect was carried out at two weeks, six months, and six years after surgery. Indirect revascularization showed more significant decreasing of the functional class (FC) New York Heart Association (NYHA), myocardial perfusion and contractility improvement. Autologous BMC implantation in laser channels is an effective method of CHD surgical treatment if it is impossible to perform direct myocardial revascularization. The indirect revascularization effect is formed in the first six months after surgery and remains at the same level for six years.

  17. KCNQ5/Kv7.5 potassium channel expression and subcellular localization in primate retinal pigment epithelium and neural retina

    PubMed Central

    Zhang, Xiaoming; Yang, Dongli

    2011-01-01

    Previous studies identified in retinal pigment epithelial (RPE) cells an M-type K+ current, which in many other cell types is mediated by channels encoded by KCNQ genes. The aim of this study was to assess the expression of KCNQ genes in the monkey RPE and neural retina. Application of the specific KCNQ channel blocker XE991 eliminated the M-type current in freshly isolated monkey RPE cells, indicating that KCNQ subunits contribute to the underlying channels. RT-PCR analysis revealed the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in the RPE and all five KCNQ transcripts in the neural retina. At the protein level, KCNQ5 was detected in the RPE, whereas both KCNQ4 and KCNQ5 were found in neural retina. In situ hybridization in frozen monkey retinal sections revealed KCNQ5 gene expression in the ganglion cell layer and the inner and outer nuclear layers of the neural retina, but results in the RPE were inconclusive due to the presence of melanin. Immunohistochemistry revealed KCNQ5 in the inner and outer plexiform layers, in cone and rod photoreceptor inner segments, and near the basal membrane of the RPE. The data suggest that KCNQ5 channels contribute to the RPE basal membrane K+ conductance and, thus, likely play an important role in active K+ absorption. The distribution of KCNQ5 in neural retina suggests that these channels may function in the shaping of the photoresponses of cone and rod photoreceptors and the processing of visual information by retinal neurons. PMID:21795522

  18. A Fully Integrated Wireless Compressed Sensing Neural Signal Acquisition System for Chronic Recording and Brain Machine Interface.

    PubMed

    Liu, Xilin; Zhang, Milin; Xiong, Tao; Richardson, Andrew G; Lucas, Timothy H; Chin, Peter S; Etienne-Cummings, Ralph; Tran, Trac D; Van der Spiegel, Jan

    2016-07-18

    Reliable, multi-channel neural recording is critical to the neuroscience research and clinical treatment. However, most hardware development of fully integrated, multi-channel wireless neural recorders to-date, is still in the proof-of-concept stage. To be ready for practical use, the trade-offs between performance, power consumption, device size, robustness, and compatibility need to be carefully taken into account. This paper presents an optimized wireless compressed sensing neural signal recording system. The system takes advantages of both custom integrated circuits and universal compatible wireless solutions. The proposed system includes an implantable wireless system-on-chip (SoC) and an external wireless relay. The SoC integrates 16-channel low-noise neural amplifiers, programmable filters and gain stages, a SAR ADC, a real-time compressed sensing module, and a near field wireless power and data transmission link. The external relay integrates a 32 bit low-power microcontroller with Bluetooth 4.0 wireless module, a programming interface, and an inductive charging unit. The SoC achieves high signal recording quality with minimized power consumption, while reducing the risk of infection from through-skin connectors. The external relay maximizes the compatibility and programmability. The proposed compressed sensing module is highly configurable, featuring a SNDR of 9.78 dB with a compression ratio of 8×. The SoC has been fabricated in a 180 nm standard CMOS technology, occupying 2.1 mm × 0.6 mm silicon area. A pre-implantable system has been assembled to demonstrate the proposed paradigm. The developed system has been successfully used for long-term wireless neural recording in freely behaving rhesus monkey.

  19. Chromatic characterization of a three-channel colorimeter using back-propagation neural networks

    NASA Astrophysics Data System (ADS)

    Pardo, P. J.; Pérez, A. L.; Suero, M. I.

    2004-09-01

    This work describes a method for the chromatic characterization of a three-channel colorimeter of recent design and construction dedicated to color vision research. The colorimeter consists of two fixed monochromators and a third monochromator interchangeable with a cathode ray tube or any other external light source. Back-propagation neural networks were used for the chromatic characterization to establish the relationship between each monochromator's input parameters and the tristimulus values of each chromatic stimulus generated. The results showed the effectiveness of this type of neural-network-based system for the chromatic characterization of the stimuli produced by any monochromator.

  20. Deactivating stimulation sites based on low-rate thresholds improves spectral ripple and speech reception thresholds in cochlear implant users.

    PubMed

    Zhou, Ning

    2017-03-01

    The study examined whether the benefit of deactivating stimulation sites estimated to have broad neural excitation was attributed to improved spectral resolution in cochlear implant users. The subjects' spatial neural excitation pattern was estimated by measuring low-rate detection thresholds across the array [see Zhou (2016). PLoS One 11, e0165476]. Spectral resolution, as assessed by spectral-ripple discrimination thresholds, significantly improved after deactivation of five high-threshold sites. The magnitude of improvement in spectral-ripple discrimination thresholds predicted the magnitude of improvement in speech reception thresholds after deactivation. Results suggested that a smaller number of relatively independent channels provide a better outcome than using all channels that might interact.

  1. Patient positioning using artificial intelligence neural networks, trained magnetic field sensors and magnetic implants.

    PubMed

    Lennernäs, B; Edgren, M; Nilsson, S

    1999-01-01

    The purpose of this study was to evaluate the precision of a sensor and to ascertain the maximum distance between the sensor and the magnet, in a magnetic positioning system for external beam radiotherapy using a trained artificial intelligence neural network for position determination. Magnetic positioning for radiotherapy, previously described by Lennernäs and Nilsson, is a functional technique, but it is time consuming. The sensors are large and the distance between the sensor and the magnetic implant is limited to short distances. This paper presents a new technique for positioning, using an artificial intelligence neural network, which was trained to position the magnetic implant with at least 0.5 mm resolution in X and Y dimensions. The possibility of using the system for determination in the Z dimension, that is the distance between the magnet and the sensor, was also investigated. After training, this system positioned the magnet with a mean error of maximum 0.15 mm in all dimensions and up to 13 mm from the sensor. Of 400 test positions, 8 determinations had an error larger than 0.5 mm, maximum 0.55 mm. A position was determined in approximately 0.01 s.

  2. Identifying cochlear implant channels with poor electrode-neuron interface: electrically-evoked auditory brainstem responses measured with the partial tripolar configuration

    PubMed Central

    Bierer, Julie Arenberg; Faulkner, Kathleen F.; Tremblay, Kelly L.

    2011-01-01

    Objectives The goal of this study was to compare cochlear implant behavioral measures and electrically-evoked auditory brainstem responses (EABRs) obtained with a spatially focused electrode configuration. It has been shown previously that channels with high thresholds, when measured with the tripolar configuration, exhibit relatively broad psychophysical tuning curves (Bierer and Faulkner, 2010). The elevated threshold and degraded spatial/spectral selectivity of such channels are consistent with a poor electrode-neuron interface, such as suboptimal electrode placement or reduced nerve survival. However, the psychophysical methods required to obtain these data are time intensive and may not be practical during a clinical mapping procedure, especially for young children. Here we have extended the previous investigation to determine if a physiological approach could provide a similar assessment of channel functionality. We hypothesized that, in accordance with the perceptual measures, higher EABR thresholds would correlate with steeper EABR amplitude growth functions, reflecting a degraded electrode-neuron interface. Design Data were collected from six cochlear implant listeners implanted with the HiRes 90k cochlear implant (Advanced Bionics). Single-channel thresholds and most comfortable listening levels were obtained for stimuli that varied in presumed electrical field size by using the partial tripolar configuration, for which a fraction of current (σ) from a center active electrode returns through two neighboring electrodes and the remainder through a distant indifferent electrode. EABRs were obtained in each subject for the two channels having the highest and lowest tripolar (σ=1 or 0.9) behavioral threshold. Evoked potentials were measured with both the monopolar (σ=0) and a more focused partial tripolar (σ ≥ 0.50) configuration. Results Consistent with previous studies, EABR thresholds were highly and positively correlated with behavioral thresholds

  3. Brain Tissue Responses to Neural Implants Impact Signal Sensitivity and Intervention Strategies

    PubMed Central

    2015-01-01

    Implantable biosensors are valuable scientific tools for basic neuroscience research and clinical applications. Neurotechnologies provide direct readouts of neurological signal and neurochemical processes. These tools are generally most valuable when performance capacities extend over months and years to facilitate the study of memory, plasticity, and behavior or to monitor patients’ conditions. These needs have generated a variety of device designs from microelectrodes for fast scan cyclic voltammetry (FSCV) and electrophysiology to microdialysis probes for sampling and detecting various neurochemicals. Regardless of the technology used, the breaching of the blood–brain barrier (BBB) to insert devices triggers a cascade of biochemical pathways resulting in complex molecular and cellular responses to implanted devices. Molecular and cellular changes in the microenvironment surrounding an implant include the introduction of mechanical strain, activation of glial cells, loss of perfusion, secondary metabolic injury, and neuronal degeneration. Changes to the tissue microenvironment surrounding the device can dramatically impact electrochemical and electrophysiological signal sensitivity and stability over time. This review summarizes the magnitude, variability, and time course of the dynamic molecular and cellular level neural tissue responses induced by state-of-the-art implantable devices. Studies show that insertion injuries and foreign body response can impact signal quality across all implanted central nervous system (CNS) sensors to varying degrees over both acute (seconds to minutes) and chronic periods (weeks to months). Understanding the underlying biological processes behind the brain tissue response to the devices at the cellular and molecular level leads to a variety of intervention strategies for improving signal sensitivity and longevity. PMID:25546652

  4. Adaptive quantization of local field potentials for wireless implants in freely moving animals: an open-source neural recording device.

    PubMed

    Martinez, Dominique; Clément, Maxime; Messaoudi, Belkacem; Gervasoni, Damien; Litaudon, Philippe; Buonviso, Nathalie

    2018-04-01

    Modern neuroscience research requires electrophysiological recording of local field potentials (LFPs) in moving animals. Wireless transmission has the advantage of removing the wires between the animal and the recording equipment but is hampered by the large number of data to be sent at a relatively high rate. To reduce transmission bandwidth, we propose an encoder/decoder scheme based on adaptive non-uniform quantization. Our algorithm uses the current transmitted codeword to adapt the quantization intervals to changing statistics in LFP signals. It is thus backward adaptive and does not require the sending of side information. The computational complexity is low and similar at the encoder and decoder sides. These features allow for real-time signal recovery and facilitate hardware implementation with low-cost commercial microcontrollers. As proof-of-concept, we developed an open-source neural recording device called NeRD. The NeRD prototype digitally transmits eight channels encoded at 10 kHz with 2 bits per sample. It occupies a volume of 2  ×  2  ×  2 cm 3 and weighs 8 g with a small battery allowing for 2 h 40 min of autonomy. The power dissipation is 59.4 mW for a communication range of 8 m and transmission losses below 0.1%. The small weight and low power consumption offer the possibility of mounting the entire device on the head of a rodent without resorting to a separate head-stage and battery backpack. The NeRD prototype is validated in recording LFPs in freely moving rats at 2 bits per sample while maintaining an acceptable signal-to-noise ratio (>30 dB) over a range of noisy channels. Adaptive quantization in neural implants allows for lower transmission bandwidths while retaining high signal fidelity and preserving fundamental frequencies in LFPs.

  5. Ultrasoft microwire neural electrodes improve chronic tissue integration

    PubMed Central

    Du, Zhanhong Jeff; Kolarcik, Christi L.; Kozai, Takashi D.Y.; Luebben, Silvia D.; Sapp, Shawn A.; Zheng, Xin Sally; Nabity, James A.; Cui, X. Tracy

    2017-01-01

    Chronically implanted neural multi-electrode arrays (MEA) are an essential technology for recording electrical signals from neurons and/or modulating neural activity through stimulation. However, current MEAs, regardless of the type, elicit an inflammatory response that ultimately leads to device failure. Traditionally, rigid materials like tungsten and silicon have been employed to interface with the relatively soft neural tissue. The large stiffness mismatch is thought to exacerbate the inflammatory response. In order to minimize the disparity between the device and the brain, we fabricated novel ultrasoft electrodes consisting of elastomers and conducting polymers with mechanical properties much more similar to those of brain tissue than previous neural implants. In this study, these ultrasoft microelectrodes were inserted and released using a stainless steel shuttle with polyethyleneglycol (PEG) glue. The implanted microwires showed functionality in acute neural stimulation. When implanted for 1 or 8 weeks, the novel soft implants demonstrated significantly reduced inflammatory tissue response at week 8 compared to tungsten wires of similar dimension and surface chemistry. Furthermore, a higher degree of cell body distortion was found next to the tungsten implants compared to the polymer implants. Our results support the use of these novel ultrasoft electrodes for long term neural implants. PMID:28185910

  6. Nonlinear channel equalization for QAM signal constellation using artificial neural networks.

    PubMed

    Patra, J C; Pal, R N; Baliarsingh, R; Panda, G

    1999-01-01

    Application of artificial neural networks (ANN's) to adaptive channel equalization in a digital communication system with 4-QAM signal constellation is reported in this paper. A novel computationally efficient single layer functional link ANN (FLANN) is proposed for this purpose. This network has a simple structure in which the nonlinearity is introduced by functional expansion of the input pattern by trigonometric polynomials. Because of input pattern enhancement, the FLANN is capable of forming arbitrarily nonlinear decision boundaries and can perform complex pattern classification tasks. Considering channel equalization as a nonlinear classification problem, the FLANN has been utilized for nonlinear channel equalization. The performance of the FLANN is compared with two other ANN structures [a multilayer perceptron (MLP) and a polynomial perceptron network (PPN)] along with a conventional linear LMS-based equalizer for different linear and nonlinear channel models. The effect of eigenvalue ratio (EVR) of input correlation matrix on the equalizer performance has been studied. The comparison of computational complexity involved for the three ANN structures is also provided.

  7. A single-channel implantable microstimulator for functional neuromuscular stimulation.

    PubMed

    Ziaie, B; Nardin, M D; Coghlan, A R; Najafi, K

    1997-10-01

    This paper describes a single-channel implantable microstimulator for functional neuromuscular stimulation. This device measures 2 x 2 x 10 mm3 and can be inserted into paralyzed muscle groups by expulsion from a hypodermic needle. Power and data to the device are supplied from outside by RF telemetry using an amplitude-modulated 2-MHz RF carrier generated using a high-efficiency class-E transmitter. The transmitted signal carries a 5-b address which selects one of the 32 possible microstimulators. The selected device then delivers up to 2 microC of charge store in a tantalum chip capacitor for up to 200 microseconds (10 mA) into loads of < 800 omega through a high-current thin-film iridium-oxide (IrOx) electrode (approximately 0.3 mm2 in area). A bi-CMOS receiver circuitry is used to: generate two regulated voltage supplies (4.5 and 9 V), recover a 2-MHz clock from the carrier, demodulate the address code, and activate the output current delivery circuitry upon the reception of an external command. The overall power dissipation of the receiver circuitry is 45-55 mW. The implant is hermetically packaged using a custom-made glass capsule.

  8. In vivo monitoring of glial scar proliferation on chronically implanted neural electrodes by fiber optical coherence tomography

    PubMed Central

    Xie, Yijing; Martini, Nadja; Hassler, Christina; Kirch, Robert D.; Stieglitz, Thomas; Seifert, Andreas; Hofmann, Ulrich G.

    2014-01-01

    In neural prosthetics and stereotactic neurosurgery, intracortical electrodes are often utilized for delivering therapeutic electrical pulses, and recording neural electrophysiological signals. Unfortunately, neuroinflammation impairs the neuron-electrode-interface by developing a compact glial encapsulation around the implants in long term. At present, analyzing this immune reaction is only feasible with post-mortem histology; currently no means for specific in vivo monitoring exist and most applicable imaging modalities can not provide information in deep brain regions. Optical coherence tomography (OCT) is a well established imaging modality for in vivo studies, providing cellular resolution and up to 1.2 mm imaging depth in brain tissue. A fiber based spectral domain OCT was shown to be capable of minimally invasive brain imaging. In the present study, we propose to use a fiber based spectral domain OCT to monitor the progression of the tissue's immune response through scar encapsulation progress in a rat animal model. A fine fiber catheter was implanted in rat brain together with a flexible polyimide microelectrode in sight both of which acts as a foreign body and induces the brain tissue immune reaction. OCT signals were collected from animals up to 12 weeks after implantation and thus gliotic scarring in vivo monitored for that time. Preliminary data showed a significant enhancement of the OCT backscattering signal during the first 3 weeks after implantation, and increased attenuation factor of the sampled tissue due to the glial scar formation. PMID:25191264

  9. Two Pore Channel 2 Differentially Modulates Neural Differentiation of Mouse Embryonic Stem Cells

    PubMed Central

    Zhang, Zhe-Hao; Lu, Ying-Ying; Yue, Jianbo

    2013-01-01

    Nicotinic acid adenine dinucleotide phosphate (NAADP) is an endogenous Ca2+ mobilizing nucleotide presented in various species. NAADP mobilizes Ca2+ from acidic organelles through two pore channel 2 (TPC2) in many cell types and it has been previously shown that NAADP can potently induce neuronal differentiation in PC12 cells. Here we examined the role of TPC2 signaling in the neural differentiation of mouse embryonic stem (ES) cells. We found that the expression of TPC2 was markedly decreased during the initial ES cell entry into neural progenitors, and the levels of TPC2 gradually rebounded during the late stages of neurogenesis. Correspondingly, TPC2 knockdown accelerated mouse ES cell differentiation into neural progenitors but inhibited these neural progenitors from committing to neurons. Overexpression of TPC2, on the other hand, inhibited mouse ES cell from entering the early neural lineage. Interestingly, TPC2 knockdown had no effect on the differentiation of astrocytes and oligodendrocytes of mouse ES cells. Taken together, our data indicate that TPC2 signaling plays a temporal and differential role in modulating the neural lineage entry of mouse ES cells, in that TPC2 signaling inhibits ES cell entry to early neural progenitors, but is required for late neuronal differentiation. PMID:23776607

  10. Chronic multisite brain recordings from a totally implantable bidirectional neural interface: experience in 5 patients with Parkinson's disease.

    PubMed

    Swann, Nicole C; de Hemptinne, Coralie; Miocinovic, Svjetlana; Qasim, Salman; Ostrem, Jill L; Galifianakis, Nicholas B; Luciano, Marta San; Wang, Sarah S; Ziman, Nathan; Taylor, Robin; Starr, Philip A

    2018-02-01

    OBJECTIVE Dysfunction of distributed neural networks underlies many brain disorders. The development of neuromodulation therapies depends on a better understanding of these networks. Invasive human brain recordings have a favorable temporal and spatial resolution for the analysis of network phenomena but have generally been limited to acute intraoperative recording or short-term recording through temporarily externalized leads. Here, the authors describe their initial experience with an investigational, first-generation, totally implantable, bidirectional neural interface that allows both continuous therapeutic stimulation and recording of field potentials at multiple sites in a neural network. METHODS Under a physician-sponsored US Food and Drug Administration investigational device exemption, 5 patients with Parkinson's disease were implanted with the Activa PC+S system (Medtronic Inc.). The device was attached to a quadripolar lead placed in the subdural space over motor cortex, for electrocorticography potential recordings, and to a quadripolar lead in the subthalamic nucleus (STN), for both therapeutic stimulation and recording of local field potentials. Recordings from the brain of each patient were performed at multiple time points over a 1-year period. RESULTS There were no serious surgical complications or interruptions in deep brain stimulation therapy. Signals in both the cortex and the STN were relatively stable over time, despite a gradual increase in electrode impedance. Canonical movement-related changes in specific frequency bands in the motor cortex were identified in most but not all recordings. CONCLUSIONS The acquisition of chronic multisite field potentials in humans is feasible. The device performance characteristics described here may inform the design of the next generation of totally implantable neural interfaces. This research tool provides a platform for translating discoveries in brain network dynamics to improved neurostimulation

  11. Wireless radio channel for intramuscular electrode implants in the control of upper limb prostheses.

    PubMed

    Stango, Antonietta; Yazdandoost, Kamya Yekeh; Farina, Dario

    2015-01-01

    In the last few years the use of implanted devices has been considered also in the field of myoelectric hand prostheses. Wireless implanted EMG (Electromyogram) sensors can improve the functioning of the prosthesis, providing information without the disadvantage of the wires, and the usability by amputees. The solutions proposed in the literature are based on proprietary communication protocols between the implanted devices and the prosthesis controller, using frequency bands that are already assigned to other purposes. This study proposes the use of a standard communication protocol (IEEE 802.15.6), specific for wireless body area networks (WBANs), which assign a specific bandwidth to implanted devices. The propagation losses from in-to-on body were investigated by numerical simulation with a 3D human model and an electromagnetic solver. The channel model resulting from the study represents the first step towards the development of myoelectric prosthetic hands which are driven by signals acquired by implanted sensors. However these results can provide important information to researchers for further developments, and manufacturers, which can decrease the production costs for hand prostheses having a common standard of communication with assigned frequencies of operation.

  12. Hermetic diamond capsules for biomedical implants enabled by gold active braze alloys.

    PubMed

    Lichter, Samantha G; Escudié, Mathilde C; Stacey, Alastair D; Ganesan, Kumaravelu; Fox, Kate; Ahnood, Arman; Apollo, Nicholas V; Kua, Dunstan C; Lee, Aaron Z; McGowan, Ceara; Saunders, Alexia L; Burns, Owen; Nayagam, David A X; Williams, Richard A; Garrett, David J; Meffin, Hamish; Prawer, Steven

    2015-01-01

    As the field of biomedical implants matures the functionality of implants is rapidly increasing. In the field of neural prostheses this is particularly apparent as researchers strive to build devices that interact with highly complex neural systems such as vision, hearing, touch and movement. A retinal implant, for example, is a highly complex device and the surgery, training and rehabilitation requirements involved in deploying such devices are extensive. Ideally, such devices will be implanted only once and will continue to function effectively for the lifetime of the patient. The first and most pivotal factor that determines device longevity is the encapsulation that separates the sensitive electronics of the device from the biological environment. This paper describes the realisation of a free standing device encapsulation made from diamond, the most impervious, long lasting and biochemically inert material known. A process of laser micro-machining and brazing is described detailing the fabrication of hermetic electrical feedthroughs and laser weldable seams using a 96.4% gold active braze alloy, another material renowned for biochemical longevity. Accelerated ageing of the braze alloy, feedthroughs and hermetic capsules yielded no evidence of corrosion and no loss of hermeticity. Samples of the gold braze implanted for 15 weeks, in vivo, caused minimal histopathological reaction and results were comparable to those obtained from medical grade silicone controls. The work described represents a first account of a free standing, fully functional hermetic diamond encapsulation for biomedical implants, enabled by gold active alloy brazing and laser micro-machining. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Identifying cochlear implant channels with poor electrode-neuron interfaces: electrically evoked auditory brain stem responses measured with the partial tripolar configuration.

    PubMed

    Bierer, Julie Arenberg; Faulkner, Kathleen F; Tremblay, Kelly L

    2011-01-01

    The goal of this study was to compare cochlear implant behavioral measures and electrically evoked auditory brain stem responses (EABRs) obtained with a spatially focused electrode configuration. It has been shown previously that channels with high thresholds, when measured with the tripolar configuration, exhibit relatively broad psychophysical tuning curves. The elevated threshold and degraded spatial/spectral selectivity of such channels are consistent with a poor electrode-neuron interface, defined as suboptimal electrode placement or reduced nerve survival. However, the psychophysical methods required to obtain these data are time intensive and may not be practical during a clinical mapping session, especially for young children. Here, we have extended the previous investigation to determine whether a physiological approach could provide a similar assessment of channel functionality. We hypothesized that, in accordance with the perceptual measures, higher EABR thresholds would correlate with steeper EABR amplitude growth functions, reflecting a degraded electrode-neuron interface. Data were collected from six cochlear implant listeners implanted with the HiRes 90k cochlear implant (Advanced Bionics). Single-channel thresholds and most comfortable listening levels were obtained for stimuli that varied in presumed electrical field size by using the partial tripolar configuration, for which a fraction of current (σ) from a center active electrode returns through two neighboring electrodes and the remainder through a distant indifferent electrode. EABRs were obtained in each subject for the two channels having the highest and lowest tripolar (σ = 1 or 0.9) behavioral threshold. Evoked potentials were measured with both the monopolar (σ = 0) and a more focused partial tripolar (σ ≥ 0.50) configuration. Consistent with previous studies, EABR thresholds were highly and positively correlated with behavioral thresholds obtained with both the monopolar and partial

  14. Modeling the Electrode-Neuron Interface of Cochlear Implants: Effects of Neural Survival, Electrode Placement, and the Partial Tripolar Configuration

    PubMed Central

    Goldwyn, Joshua H.; Bierer, Steven M.; Bierer, Julie A.

    2010-01-01

    The partial tripolar electrode configuration is a relatively novel stimulation strategies that can generate more spatially focused electric fields than the commonly used monopolar configuration. Focused stimulation strategies should improve spectral resolution in cochlear implant users, but may also be more sensitive to local irregularities in the electrode-neuron interface. In this study, we develop a practical computer model of cochlear implant stimulation that can simulate neural activation in a simplified cochlear geometry and we relate the resulting patterns of neural activity to basic psychophysical measures. We examine how two types of local irregularities in the electrode-neuron interface, variations in spiral ganglion nerve density and electrode position within the scala tympani, affect the simulated neural activation patterns and how these patterns change with electrode configuration. The model shows that higher partial tripolar fractions activate more spatially restricted populations of neurons at all current levels and require higher current levels to excite a given number of neurons. We find that threshold levels are more sensitive at high partial tripolar fractions to both types of irregularities, but these effects are not independent. In particular, at close electrode-neuron distances, activation is typically more spatially localized which leads to a greater influence of neural dead regions. PMID:20580801

  15. Modeling the electrode-neuron interface of cochlear implants: effects of neural survival, electrode placement, and the partial tripolar configuration.

    PubMed

    Goldwyn, Joshua H; Bierer, Steven M; Bierer, Julie Arenberg

    2010-09-01

    The partial tripolar electrode configuration is a relatively novel stimulation strategy that can generate more spatially focused electric fields than the commonly used monopolar configuration. Focused stimulation strategies should improve spectral resolution in cochlear implant users, but may also be more sensitive to local irregularities in the electrode-neuron interface. In this study, we develop a practical computer model of cochlear implant stimulation that can simulate neural activation in a simplified cochlear geometry and we relate the resulting patterns of neural activity to basic psychophysical measures. We examine how two types of local irregularities in the electrode-neuron interface, variations in spiral ganglion nerve density and electrode position within the scala tympani, affect the simulated neural activation patterns and how these patterns change with electrode configuration. The model shows that higher partial tripolar fractions activate more spatially restricted populations of neurons at all current levels and require higher current levels to excite a given number of neurons. We find that threshold levels are more sensitive at high partial tripolar fractions to both types of irregularities, but these effects are not independent. In particular, at close electrode-neuron distances, activation is typically more spatially localized which leads to a greater influence of neural dead regions. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  16. Anaesthetic Tricaine Acts Preferentially on Neural Voltage-Gated Sodium Channels and Fails to Block Directly Evoked Muscle Contraction

    PubMed Central

    Attili, Seetharamaiah; Hughes, Simon M.

    2014-01-01

    Movements in animals arise through concerted action of neurons and skeletal muscle. General anaesthetics prevent movement and cause loss of consciousness by blocking neural function. Anaesthetics of the amino amide-class are thought to act by blockade of voltage-gated sodium channels. In fish, the commonly used anaesthetic tricaine methanesulphonate, also known as 3-aminobenzoic acid ethyl ester, metacaine or MS-222, causes loss of consciousness. However, its role in blocking action potentials in distinct excitable cells is unclear, raising the possibility that tricaine could act as a neuromuscular blocking agent directly causing paralysis. Here we use evoked electrical stimulation to show that tricaine efficiently blocks neural action potentials, but does not prevent directly evoked muscle contraction. Nifedipine-sensitive L-type Cav channels affecting movement are also primarily neural, suggesting that muscle Nav channels are relatively insensitive to tricaine. These findings show that tricaine used at standard concentrations in zebrafish larvae does not paralyse muscle, thereby diminishing concern that a direct action on muscle could mask a lack of general anaesthesia. PMID:25090007

  17. On the estimation of the worst-case implant-induced RF-heating in multi-channel MRI.

    PubMed

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2017-06-21

    The increasing use of multiple radiofrequency (RF) transmit channels in magnetic resonance imaging (MRI) systems makes it necessary to rigorously assess the risk of RF-induced heating. This risk is especially aggravated with inclusions of medical implants within the body. The worst-case RF-heating scenario is achieved when the local tissue deposition in the at-risk region (generally in the vicinity of the implant electrodes) reaches its maximum value while MRI exposure is compliant with predefined general specific absorption rate (SAR) limits or power requirements. This work first reviews the common approach to estimate the worst-case RF-induced heating in multi-channel MRI environment, based on the maximization of the ratio of two Hermitian forms by solving a generalized eigenvalue problem. It is then shown that the common approach is not rigorous and may lead to an underestimation of the worst-case RF-heating scenario when there is a large number of RF transmit channels and there exist multiple SAR or power constraints to be satisfied. Finally, this work derives a rigorous SAR-based formulation to estimate a preferable worst-case scenario, which is solved by casting a semidefinite programming relaxation of this original non-convex problem, whose solution closely approximates the true worst-case including all SAR constraints. Numerical results for 2, 4, 8, 16, and 32 RF channels in a 3T-MRI volume coil for a patient with a deep-brain stimulator under a head imaging exposure are provided as illustrative examples.

  18. On the estimation of the worst-case implant-induced RF-heating in multi-channel MRI

    NASA Astrophysics Data System (ADS)

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2017-06-01

    The increasing use of multiple radiofrequency (RF) transmit channels in magnetic resonance imaging (MRI) systems makes it necessary to rigorously assess the risk of RF-induced heating. This risk is especially aggravated with inclusions of medical implants within the body. The worst-case RF-heating scenario is achieved when the local tissue deposition in the at-risk region (generally in the vicinity of the implant electrodes) reaches its maximum value while MRI exposure is compliant with predefined general specific absorption rate (SAR) limits or power requirements. This work first reviews the common approach to estimate the worst-case RF-induced heating in multi-channel MRI environment, based on the maximization of the ratio of two Hermitian forms by solving a generalized eigenvalue problem. It is then shown that the common approach is not rigorous and may lead to an underestimation of the worst-case RF-heating scenario when there is a large number of RF transmit channels and there exist multiple SAR or power constraints to be satisfied. Finally, this work derives a rigorous SAR-based formulation to estimate a preferable worst-case scenario, which is solved by casting a semidefinite programming relaxation of this original non-convex problem, whose solution closely approximates the true worst-case including all SAR constraints. Numerical results for 2, 4, 8, 16, and 32 RF channels in a 3T-MRI volume coil for a patient with a deep-brain stimulator under a head imaging exposure are provided as illustrative examples.

  19. An in vivo assessment of the effects of using different implant abutment occluding materials on implant microleakage and the peri-implant microbiome

    NASA Astrophysics Data System (ADS)

    Rubino, Caroline

    Microleakage may be a factor in the progression of peri-implant pathology. Microleakage in implant dentistry refers to the passage of bacteria, fluids, molecules or ions between the abutment-implant interface to and from the surrounding periodontal tissues. This creates a zone of inflammation and reservoir of bacteria at the implant-abutment interface. Bone loss typically occurs within the first year of abutment connection and then stabilizes. It has not yet been definitively proven that the occurrence of microleakage cannot contribute to future bone loss or impede the treatment of peri-implant disease. Therefore, strategies to reduce or eliminate microleakage are sought out. Recent evidence demonstrates that the type of implant abutment channel occluding material can affect the amount of microleakage in an in vitro study environment. Thus, we hypothesize that different abutment screw channel occluding materials will affect the amount of observed microleakage, vis-a-vis the correlation between the microflora found on the abutment screw channel occluding material those found in the peri-implant sulcus. Additional objectives include confirming the presence of microleakage in vivo and assessing any impact that different abutment screw channel occluding materials may have on the peri-implant microbiome. Finally, the present study provides an opportunity to further characterize the peri-implant microbiome. Eight fully edentulous patients restored with at dental implants supporting screw-retained fixed hybrid prostheses were included in the study. At the initial appointment (T1), the prostheses were removed and the implants and prostheses were cleaned. The prostheses were then inserted with polytetrafluoroethylene tape (PTFE, TeflonRTM), cotton, polyvinyl siloxane (PVS), or synthetic foam as the implant abutment channel occluding material and sealed over with composite resin. About six months later (T2), the prostheses were removed and the materials collected. Paper

  20. Suppression of scarring in peripheral nerve implants by drug elution.

    PubMed

    FitzGerald, James J

    2016-04-01

    Medical implants made of non-biological materials provoke a chronic inflammatory response, resulting in the deposition of a collagenous scar tissue (ST) layer on their surface, that gradually thickens over time. This is a critical problem for neural interfaces. Scar build-up on electrodes results in a progressive decline in signal level because the scar tissue gradually separates axons away from the recording contacts. In regenerative sieves and microchannel electrodes, progressive scar deposition will constrict and may eventually choke off the sieve hole or channel lumen. Interface designs need to address this issue if they are to be fit for long term use. This study examines a novel method of inhibiting the formation and thickening of the fibrous scar. Research to date has mainly focused on methods of preventing stimulation of the foreign body response by implant surface modification. In this paper a pharmacological approach using drug elution to suppress chronic inflammation is introduced. Microchannel implants made of silicone doped with the steroid drug dexamethasone were implanted in the rat sciatic nerve for periods of up to a year. Tissue from within the microchannels was compared to that from control devices that did not release any drug. In the drug eluting implants the scar layer was significantly thinner at all timepoints, and unlike the controls it did not continue to thicken after 6 months. Control implants supported axon regeneration well initially, but axon counts fell rapidly at later timepoints as scar thickened. Axon counts in drug eluting devices were initially much lower, but increased rather than declined and by one year were significantly higher than in controls. Drug elution offers a potential long term solution to the problem of performance degradation due to scarring around neural implants.

  1. Suppression of scarring in peripheral nerve implants by drug elution

    NASA Astrophysics Data System (ADS)

    FitzGerald, James J.

    2016-04-01

    Objective. Medical implants made of non-biological materials provoke a chronic inflammatory response, resulting in the deposition of a collagenous scar tissue (ST) layer on their surface, that gradually thickens over time. This is a critical problem for neural interfaces. Scar build-up on electrodes results in a progressive decline in signal level because the scar tissue gradually separates axons away from the recording contacts. In regenerative sieves and microchannel electrodes, progressive scar deposition will constrict and may eventually choke off the sieve hole or channel lumen. Interface designs need to address this issue if they are to be fit for long term use. This study examines a novel method of inhibiting the formation and thickening of the fibrous scar. Approach. Research to date has mainly focused on methods of preventing stimulation of the foreign body response by implant surface modification. In this paper a pharmacological approach using drug elution to suppress chronic inflammation is introduced. Microchannel implants made of silicone doped with the steroid drug dexamethasone were implanted in the rat sciatic nerve for periods of up to a year. Tissue from within the microchannels was compared to that from control devices that did not release any drug. Main results. In the drug eluting implants the scar layer was significantly thinner at all timepoints, and unlike the controls it did not continue to thicken after 6 months. Control implants supported axon regeneration well initially, but axon counts fell rapidly at later timepoints as scar thickened. Axon counts in drug eluting devices were initially much lower, but increased rather than declined and by one year were significantly higher than in controls. Significance. Drug elution offers a potential long term solution to the problem of performance degradation due to scarring around neural implants.

  2. Neural Processing of Musical and Vocal Emotions Through Cochlear Implants Simulation.

    PubMed

    Ahmed, Duha G; Paquette, Sebastian; Zeitouni, Anthony; Lehmann, Alexandre

    2018-05-01

    Cochlear implants (CIs) partially restore the sense of hearing in the deaf. However, the ability to recognize emotions in speech and music is reduced due to the implant's electrical signal limitations and the patient's altered neural pathways. Electrophysiological correlations of these limitations are not yet well established. Here we aimed to characterize the effect of CIs on auditory emotion processing and, for the first time, directly compare vocal and musical emotion processing through a CI-simulator. We recorded 16 normal hearing participants' electroencephalographic activity while listening to vocal and musical emotional bursts in their original form and in a degraded (CI-simulated) condition. We found prolonged P50 latency and reduced N100-P200 complex amplitude in the CI-simulated condition. This points to a limitation in encoding sound signals processed through CI simulation. When comparing the processing of vocal and musical bursts, we found a delay in latency with the musical bursts compared to the vocal bursts in both conditions (original and CI-simulated). This suggests that despite the cochlear implants' limitations, the auditory cortex can distinguish between vocal and musical stimuli. In addition, it adds to the literature supporting the complexity of musical emotion. Replicating this study with actual CI users might lead to characterizing emotional processing in CI users and could ultimately help develop optimal rehabilitation programs or device processing strategies to improve CI users' quality of life.

  3. RBS-channeling study of radiation damage in Ar{sup +} implanted CuInSe{sub 2} crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yakushev, Michael V., E-mail: michael.yakushev@strath.ac.uk; Ural Federal University, Ekaterinburg 620002; Institute of Solid State Chemistry of the Urals Branch of RAS, Ekaterinburg 620990

    2016-09-15

    Chalcopyrite solar cells are reported to have a high tolerance to irradiation by high energy electrons or ions, but the origin of this is not well understood. This work studies the evolution of damage in Ar{sup +}-bombarded CuInSe{sub 2} single crystal using Rutherford backscattering/channeling analysis. Ar{sup +} ions of 30 keV were implanted with doses in the range from 10{sup 12} to 3 × 10{sup 16} cm{sup −2} at room temperature. Implantation was found to create two layers of damage: (1) on the surface, caused by preferential sputtering of Se and Cu atoms; (2) at the layer of implanted Ar, possibly consisting of stackingmore » faults and dislocation loops. The damage in the second layer was estimated to be less than 2% of the theoretical prediction suggesting efficient healing of primary implantation defects.« less

  4. Neural signal processing and closed-loop control algorithm design for an implanted neural recording and stimulation system.

    PubMed

    Hamilton, Lei; McConley, Marc; Angermueller, Kai; Goldberg, David; Corba, Massimiliano; Kim, Louis; Moran, James; Parks, Philip D; Sang Chin; Widge, Alik S; Dougherty, Darin D; Eskandar, Emad N

    2015-08-01

    A fully autonomous intracranial device is built to continually record neural activities in different parts of the brain, process these sampled signals, decode features that correlate to behaviors and neuropsychiatric states, and use these features to deliver brain stimulation in a closed-loop fashion. In this paper, we describe the sampling and stimulation aspects of such a device. We first describe the signal processing algorithms of two unsupervised spike sorting methods. Next, we describe the LFP time-frequency analysis and feature derivation from the two spike sorting methods. Spike sorting includes a novel approach to constructing a dictionary learning algorithm in a Compressed Sensing (CS) framework. We present a joint prediction scheme to determine the class of neural spikes in the dictionary learning framework; and, the second approach is a modified OSort algorithm which is implemented in a distributed system optimized for power efficiency. Furthermore, sorted spikes and time-frequency analysis of LFP signals can be used to generate derived features (including cross-frequency coupling, spike-field coupling). We then show how these derived features can be used in the design and development of novel decode and closed-loop control algorithms that are optimized to apply deep brain stimulation based on a patient's neuropsychiatric state. For the control algorithm, we define the state vector as representative of a patient's impulsivity, avoidance, inhibition, etc. Controller parameters are optimized to apply stimulation based on the state vector's current state as well as its historical values. The overall algorithm and software design for our implantable neural recording and stimulation system uses an innovative, adaptable, and reprogrammable architecture that enables advancement of the state-of-the-art in closed-loop neural control while also meeting the challenges of system power constraints and concurrent development with ongoing scientific research designed

  5. Spontaneous calcium transients in human neural progenitor cells mediated by transient receptor potential channels.

    PubMed

    Morgan, Peter J; Hübner, Rayk; Rolfs, Arndt; Frech, Moritz J

    2013-09-15

    Calcium signals affect many developmental processes, including proliferation, migration, survival, and apoptosis, processes that are of particular importance in stem cells intended for cell replacement therapies. The mechanisms underlying Ca(2+) signals, therefore, have a role in determining how stem cells respond to their environment, and how these responses might be controlled in vitro. In this study, we examined the spontaneous Ca(2+) activity in human neural progenitor cells during proliferation and differentiation. Pharmacological characterization indicates that in proliferating cells, most activity is the result of transient receptor potential (TRP) channels that are sensitive to Gd(3+) and La(3+), with the more subtype selective antagonist Ruthenium red also reducing activity, suggesting the involvement of transient receptor potential vanilloid (TRPV) channels. In differentiating cells, Gd(3+) and La(3+)-sensitive TRP channels also appear to underlie the spontaneous activity; however, no sub-type-specific antagonists had any effect. Protein levels of TRPV2 and TRPV3 decreased in differentiated cells, which is demonstrated by western blot. Thus, it appears that TRP channels represent the main route of Ca(2+) entry in human neural progenitor cells (hNPCs), but the responsible channel types are subject to substitution under differentiating conditions. The level of spontaneous activity could be increased and decreased by lowering and raising the extracellular K(+) concentration. Proliferating cells in low K(+) slowed the cell cycle, with a disproportionate increased percentage of cells in G1 phase and a reduction in S phase. Taken together, these results suggest a link between external K(+) concentration, spontaneous Ca(2+) transients, and cell cycle distribution, which is able to influence the fate of stem and progenitor cells.

  6. A multi-channel low-power system-on-chip for single-unit recording and narrowband wireless transmission of neural signal.

    PubMed

    Bonfanti, A; Ceravolo, M; Zambra, G; Gusmeroli, R; Spinelli, A S; Lacaita, A L; Angotzi, G N; Baranauskas, G; Fadiga, L

    2010-01-01

    This paper reports a multi-channel neural recording system-on-chip (SoC) with digital data compression and wireless telemetry. The circuit consists of a 16 amplifiers, an analog time division multiplexer, an 8-bit SAR AD converter, a digital signal processor (DSP) and a wireless narrowband 400-MHz binary FSK transmitter. Even though only 16 amplifiers are present in our current die version, the whole system is designed to work with 64 channels demonstrating the feasibility of a digital processing and narrowband wireless transmission of 64 neural recording channels. A digital data compression, based on the detection of action potentials and storage of correspondent waveforms, allows the use of a 1.25-Mbit/s binary FSK wireless transmission. This moderate bit-rate and a low frequency deviation, Manchester-coded modulation are crucial for exploiting a narrowband wireless link and an efficient embeddable antenna. The chip is realized in a 0.35- εm CMOS process with a power consumption of 105 εW per channel (269 εW per channel with an extended transmission range of 4 m) and an area of 3.1 × 2.7 mm(2). The transmitted signal is captured by a digital TV tuner and demodulated by a wideband phase-locked loop (PLL), and then sent to a PC via an FPGA module. The system has been tested for electrical specifications and its functionality verified in in-vivo neural recording experiments.

  7. Monopolar Detection Thresholds Predict Spatial Selectivity of Neural Excitation in Cochlear Implants: Implications for Speech Recognition

    PubMed Central

    2016-01-01

    The objectives of the study were to (1) investigate the potential of using monopolar psychophysical detection thresholds for estimating spatial selectivity of neural excitation with cochlear implants and to (2) examine the effect of site removal on speech recognition based on the threshold measure. Detection thresholds were measured in Cochlear Nucleus® device users using monopolar stimulation for pulse trains that were of (a) low rate and long duration, (b) high rate and short duration, and (c) high rate and long duration. Spatial selectivity of neural excitation was estimated by a forward-masking paradigm, where the probe threshold elevation in the presence of a forward masker was measured as a function of masker-probe separation. The strength of the correlation between the monopolar thresholds and the slopes of the masking patterns systematically reduced as neural response of the threshold stimulus involved interpulse interactions (refractoriness and sub-threshold adaptation), and spike-rate adaptation. Detection threshold for the low-rate stimulus most strongly correlated with the spread of forward masking patterns and the correlation reduced for long and high rate pulse trains. The low-rate thresholds were then measured for all electrodes across the array for each subject. Subsequently, speech recognition was tested with experimental maps that deactivated five stimulation sites with the highest thresholds and five randomly chosen ones. Performance with deactivating the high-threshold sites was better than performance with the subjects’ clinical map used every day with all electrodes active, in both quiet and background noise. Performance with random deactivation was on average poorer than that with the clinical map but the difference was not significant. These results suggested that the monopolar low-rate thresholds are related to the spatial neural excitation patterns in cochlear implant users and can be used to select sites for more optimal speech

  8. 3D hybrid electrode structure as implantable interface for a vestibular neural prosthesis in humans.

    PubMed

    Hoffmann, Klaus-P; Poppendieck, Wigand; Tätzner, Simon; DiGiovanna, Jack; Kos, Maria Izabel; Guinand, Nils; Guyot, Jean-P; Micera, Silvestro

    2011-01-01

    Implantable interfaces are essential components of vestibular neural prostheses. They interface the biological system with electrical stimulation that is used to restore transfer of vestibular information. Regarding the anatomical situation special 3D structures are required. In this paper, the design and the manufacturing process of a novel 3D hybrid microelectrode structure as interface to the human vestibular system are described. Photolithography techniques, assembling technology and rapid prototyping are used for manufacturing.

  9. A Multi-channel Semicircular Canal Neural Prosthesis Using Electrical Stimulation to Restore 3D Vestibular Sensation

    PubMed Central

    Della Santina, Charles C.; Migliaccio, Americo A.; Patel, Amit H.

    2009-01-01

    Bilateral loss of vestibular sensation can be disabling. Those afflicted suffer illusory visual field movement during head movements, chronic disequilibrium and postural instability due to failure of vestibulo-ocular and vestibulo-spinal reflexes. A neural prosthesis that emulates the normal transduction of head rotation by semicircular canals could significantly improve quality of life for these patients. Like the 3 semicircular canals in a normal ear, such a device should at least transduce 3 orthogonal (or linearly separable) components of head rotation into activity on corresponding ampullary branches of the vestibular nerve. We describe the design, circuit performance and in vivo application of a head-mounted, semi-implantable multi-channel vestibular prosthesis that encodes head movement in 3 dimensions as pulse-frequency-modulated electrical stimulation of 3 or more ampullary nerves. In chinchillas treated with intratympanic gentamicin to ablate vestibular sensation bilaterally, prosthetic stimuli elicited a partly compensatory angular vestibulo-ocular reflex in multiple planes. Minimizing misalignment between the axis of eye and head rotation, apparently caused by current spread beyond each electrode’s targeted nerve branch, emerged as a key challenge. Increasing stimulation selectivity via improvements in electrode design, surgical technique and stimulus protocol will likely be required to restore AVOR function over the full range of normal behavior. PMID:17554821

  10. Adaptive quantization of local field potentials for wireless implants in freely moving animals: an open-source neural recording device

    NASA Astrophysics Data System (ADS)

    Martinez, Dominique; Clément, Maxime; Messaoudi, Belkacem; Gervasoni, Damien; Litaudon, Philippe; Buonviso, Nathalie

    2018-04-01

    Objective. Modern neuroscience research requires electrophysiological recording of local field potentials (LFPs) in moving animals. Wireless transmission has the advantage of removing the wires between the animal and the recording equipment but is hampered by the large number of data to be sent at a relatively high rate. Approach. To reduce transmission bandwidth, we propose an encoder/decoder scheme based on adaptive non-uniform quantization. Our algorithm uses the current transmitted codeword to adapt the quantization intervals to changing statistics in LFP signals. It is thus backward adaptive and does not require the sending of side information. The computational complexity is low and similar at the encoder and decoder sides. These features allow for real-time signal recovery and facilitate hardware implementation with low-cost commercial microcontrollers. Main results. As proof-of-concept, we developed an open-source neural recording device called NeRD. The NeRD prototype digitally transmits eight channels encoded at 10 kHz with 2 bits per sample. It occupies a volume of 2  ×  2  ×  2 cm3 and weighs 8 g with a small battery allowing for 2 h 40 min of autonomy. The power dissipation is 59.4 mW for a communication range of 8 m and transmission losses below 0.1%. The small weight and low power consumption offer the possibility of mounting the entire device on the head of a rodent without resorting to a separate head-stage and battery backpack. The NeRD prototype is validated in recording LFPs in freely moving rats at 2 bits per sample while maintaining an acceptable signal-to-noise ratio (>30 dB) over a range of noisy channels. Significance. Adaptive quantization in neural implants allows for lower transmission bandwidths while retaining high signal fidelity and preserving fundamental frequencies in LFPs.

  11. Channeling implantation of high energy carbon ions in a diamond crystal: Determination of the induced crystal amorphization

    NASA Astrophysics Data System (ADS)

    Erich, M.; Kokkoris, M.; Fazinić, S.; Petrović, S.

    2018-02-01

    This work reports on the induced diamond crystal amorphization by 4 MeV carbon ions implanted in the 〈1 0 0〉 oriented crystal and its determination by application of RBS/C and EBS/C techniques. The spectra from the implanted samples were recorded for 1.2, 1.5, 1.75 and 1.9 MeV protons. For the two latter ones the strong resonance of the nuclear elastic scattering 12C(p,p0)12C at 1.737 MeV was explored. The backscattering channeling spectra were successfully fitted and the ion beam induced crystal amorphization depth profile was determined using a phenomenological approach, which is based on the properly defined Gompertz type dechanneling functions for protons in the 〈1 0 0〉 diamond crystal channels and the introduction of the concept of ion beam amorphization, which is implemented through our newly developed computer code CSIM.

  12. Platelet-rich plasma for regeneration of neural feedback pathways around dental implants: a concise review and outlook on future possibilities

    PubMed Central

    Huang, Yan; Bornstein, Michael M; Lambrichts, Ivo; Yu, Hai-Yang; Politis, Constantinus; Jacobs, Reinhilde

    2017-01-01

    Along with the development of new materials, advanced medical imaging and surgical techniques, osseointegrated dental implants are considered a successful and constantly evolving treatment modality for the replacement of missing teeth in patients with complete or partial edentulism. The importance of restoring the peripheral neural feedback pathway and thus repairing the lack of periodontal mechanoreceptors after tooth extraction has been highlighted in the literature. Nevertheless, regenerating the nerve fibers and reconstructing the neural feedback pathways around osseointegrated implants remain a challenge. Recent studies have provided evidence that platelet-rich plasma (PRP) therapy is a promising treatment for musculoskeletal injuries. Because of its high biological safety, convenience and usability, PRP therapy has gradually gained popularity in the clinical field. Although much remains to be learned, the growth factors from PRP might play key roles in peripheral nerve repair mechanisms. This review presents known growth factors contributing to the biological efficacy of PRP and illustrates basic and (pre-)clinical evidence regarding the use of PRP and its relevant products in peripheral nerve regeneration. In addition, the potential of local application of PRP for structural and functional recovery of injured peripheral nerves around dental implants is discussed. PMID:28282030

  13. Poly(3,4-ethylenedioxythiophene) (PEDOT) polymer coatings facilitate smaller neural recording electrodes

    NASA Astrophysics Data System (ADS)

    Ludwig, Kip A.; Langhals, Nicholas B.; Joseph, Mike D.; Richardson-Burns, Sarah M.; Hendricks, Jeffrey L.; Kipke, Daryl R.

    2011-02-01

    We investigated using poly(3,4-ethylenedioxythiophene) (PEDOT) to lower the impedance of small, gold recording electrodes with initial impedances outside of the effective recording range. Smaller electrode sites enable more densely packed arrays, increasing the number of input and output channels to and from the brain. Moreover, smaller electrode sizes promote smaller probe designs; decreasing the dimensions of the implanted probe has been demonstrated to decrease the inherent immune response, a known contributor to the failure of long-term implants. As expected, chronically implanted control electrodes were unable to record well-isolated unit activity, primarily as a result of a dramatically increased noise floor. Conversely, electrodes coated with PEDOT consistently recorded high-quality neural activity, and exhibited a much lower noise floor than controls. These results demonstrate that PEDOT coatings enable electrode designs 15 µm in diameter.

  14. A Wireless Implantable Switched-Capacitor Based Optogenetic Stimulating System

    PubMed Central

    Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen

    2015-01-01

    This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments. PMID:25570099

  15. Change detection in multitemporal synthetic aperture radar images using dual-channel convolutional neural network

    NASA Astrophysics Data System (ADS)

    Liu, Tao; Li, Ying; Cao, Ying; Shen, Qiang

    2017-10-01

    This paper proposes a model of dual-channel convolutional neural network (CNN) that is designed for change detection in SAR images, in an effort to acquire higher detection accuracy and lower misclassification rate. This network model contains two parallel CNN channels, which can extract deep features from two multitemporal SAR images. For comparison and validation, the proposed method is tested along with other change detection algorithms on both simulated SAR images and real-world SAR images captured by different sensors. The experimental results demonstrate that the presented method outperforms the state-of-the-art techniques by a considerable margin.

  16. Investigation on the hermeticity of an implantable package with 32 feedthroughs for neural prosthetic applications.

    PubMed

    Bisoni, Lorenzo; Mueller, Matthias; Cvancara, Paul; Carboni, Caterina; Puddu, Roberto; Raffo, Luigi; Barbaro, Massimo; Stieglitz, Thomas

    2016-08-01

    This paper presents an implantable package aimed at hosting a bidirectional neural interface for neural prosthetic applications. The package has been conceived to minimize the invasivity for the patient, for this reason a cylindrical container with an outer diameter of 7 mm and a length of 21 mm has been designed. The package, realized in alumina (Al2O3), presents 32 hermetic feedthroughs located at the top and bottom base of the cylinder. The hermetic housing has been assembled using a low-temperature soldering method based on a previous platinum/gold (Pt/Au) metallization of the ceramic parts. The package's hermeticity has been successfully proved by means of in-vitro tests, exhibiting an increase in the inner relative humidity of 20 %RH over 75 days of observation.

  17. Study of t$$\\bar{t}$$ production in tau jets channel at CDFII using neural networks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Amerio, Silvia

    CDF (Collider Detector at Fermilab) is a particle detector located at Fermi National Laboratories, near Chicago. it allows to study decay products of pmore » $$\\bar{p}$$ collisions at center-of-mass energy of 1.96 TeV. During its first period of data taking (RunI), CDF observed for the first time the top quark (1995). The current period of data taking (RunII) is devoted to precise measurements of top properties and to search for new physics. This thesis work is about the top decay channel named τ + jets. A t$$\\bar{t}$$ pair decays in two W bosons and two b quarks. In a τ + jets event, one out of the two W decays into two jets of hadrons, while the other produces a τ lepton and a neutrino; the τ decays semileptonically in one or more charged and neutral pions while b quarks hadronize producing two jets of particles. Thus the final state of a τ + jets event has this specific signature: five jets, one τ-like, i.e. narrow and with low track multiplicity, two from b quarks, two from a W boson and a large amount of missing energy from two τ neutrinos. They search for this signal in 311 pb -1 of data collected with TOP{_}MULTIJET trigger. They use neural networks to separate signal from background and on the selected sample they perform a t$$\\bar{t}$$ production cross section measurement. The thesis is structured as follows: in Chapter 1 they outline the physics of top and τ, concentrating on their discovery, production mechanisms and current physics results involving them. Chapter 2 is devoted to the description of the experimental setup: the accelerator complex first and CDF detector then. The trigger system is described in Chapter 3, while Chapter 4 shows how particles are reconstructed exploiting information from different CDF subdetectors. With Chapter 5 they begin to present their analysis: we use a feed forward neural network based on a minimization algorithm developed in Trento University, called Reactive Taboo Search (RTS), especially designed to

  18. Envelope Interactions in Multi-Channel Amplitude Modulation Frequency Discrimination by Cochlear Implant Users.

    PubMed

    Galvin, John J; Oba, Sandra I; Başkent, Deniz; Chatterjee, Monita; Fu, Qian-Jie

    2015-01-01

    Previous cochlear implant (CI) studies have shown that single-channel amplitude modulation frequency discrimination (AMFD) can be improved when coherent modulation is delivered to additional channels. It is unclear whether the multi-channel advantage is due to increased loudness, multiple envelope representations, or to component channels with better temporal processing. Measuring envelope interference may shed light on how modulated channels can be combined. In this study, multi-channel AMFD was measured in CI subjects using a 3-alternative forced-choice, non-adaptive procedure ("which interval is different?"). For the reference stimulus, the reference AM (100 Hz) was delivered to all 3 channels. For the probe stimulus, the target AM (101, 102, 104, 108, 116, 132, 164, 228, or 256 Hz) was delivered to 1 of 3 channels, and the reference AM (100 Hz) delivered to the other 2 channels. The spacing between electrodes was varied to be wide or narrow to test different degrees of channel interaction. Results showed that CI subjects were highly sensitive to interactions between the reference and target envelopes. However, performance was non-monotonic as a function of target AM frequency. For the wide spacing, there was significantly less envelope interaction when the target AM was delivered to the basal channel. For the narrow spacing, there was no effect of target AM channel. The present data were also compared to a related previous study in which the target AM was delivered to a single channel or to all 3 channels. AMFD was much better with multiple than with single channels whether the target AM was delivered to 1 of 3 or to all 3 channels. For very small differences between the reference and target AM frequencies (2-4 Hz), there was often greater sensitivity when the target AM was delivered to 1 of 3 channels versus all 3 channels, especially for narrowly spaced electrodes. Besides the increased loudness, the present results also suggest that multiple envelope

  19. Effects of nitric oxide on expressions of nitrosocysteine and calcium-activated potassium channels in the supraoptic nuclei and neural lobe of dehydrated rats

    PubMed Central

    Kadekaro, Massako; Su, Guangxiao; Chu, Rong; Lei, Yongzhong; Li, Junfa; Fang, Li

    2007-01-01

    Nitric oxide (NO) is an important gas mediator in the signal transduction cascade regulating osmotic function in the hypothalamo-neurohypophysial system. We previously found that increased nitric oxide synthase (NOS) activity in the supraoptic nuclei (SON) and neural lobe following osmotic stimulation and NO could regulate the expression of Ca2+-activated K+ channel (BK channels) protein in the magnocellular system during dehydration. The aim of the current study is to examine the role of NO in the regulation of nitrosocysteine and BK channel protein in the magnocellular system in dehydrated animals. Using Western blot analysis and quantitative immunofluorescent staining study, we found that water deprivation in rats significantly enhanced the expression of nitrosocysteine protein in SON and neural lobes. Immunohistochemistry study indicated that dehydration significantly increased the profiles of SON neurons co-expressing nitrosocysteine with BK-channel protein. Intracerebroventricular administration of L-NAME (an inhibitor of NO synthase) significantly reduced the neuronal profiles of nitrosocysteine, as well as their co-expression with BK-channel in SON of dehydrated rats. However, treatment of sodium nitroprusside (a donor of NO) increased this co-expression. Our results indicate that NO signaling cascade may control the expression of BK channels through the regulation of nitrosocysteine in SON and neural lobe of rats during osmotic regulation. PMID:17098363

  20. Design of a robust baseband LPC coder for speech transmission over 9.6 kbit/s noisy channels

    NASA Astrophysics Data System (ADS)

    Viswanathan, V. R.; Russell, W. H.; Higgins, A. L.

    1982-04-01

    This paper describes the design of a baseband Linear Predictive Coder (LPC) which transmits speech over 9.6 kbit/sec synchronous channels with random bit errors of up to 1%. Presented are the results of our investigation of a number of aspects of the baseband LPC coder with the goal of maximizing the quality of the transmitted speech. Important among these aspects are: bandwidth of the baseband, coding of the baseband residual, high-frequency regeneration, and error protection of important transmission parameters. The paper discusses these and other issues, presents the results of speech-quality tests conducted during the various stages of optimization, and describes the details of the optimized speech coder. This optimized speech coding algorithm has been implemented as a real-time full-duplex system on an array processor. Informal listening tests of the real-time coder have shown that the coder produces good speech quality in the absence of channel bit errors and introduces only a slight degradation in quality for channel bit error rates of up to 1%.

  1. Ultrasoft microwire neural electrodes improve chronic tissue integration.

    PubMed

    Du, Zhanhong Jeff; Kolarcik, Christi L; Kozai, Takashi D Y; Luebben, Silvia D; Sapp, Shawn A; Zheng, Xin Sally; Nabity, James A; Cui, X Tracy

    2017-04-15

    Chronically implanted neural multi-electrode arrays (MEA) are an essential technology for recording electrical signals from neurons and/or modulating neural activity through stimulation. However, current MEAs, regardless of the type, elicit an inflammatory response that ultimately leads to device failure. Traditionally, rigid materials like tungsten and silicon have been employed to interface with the relatively soft neural tissue. The large stiffness mismatch is thought to exacerbate the inflammatory response. In order to minimize the disparity between the device and the brain, we fabricated novel ultrasoft electrodes consisting of elastomers and conducting polymers with mechanical properties much more similar to those of brain tissue than previous neural implants. In this study, these ultrasoft microelectrodes were inserted and released using a stainless steel shuttle with polyethyleneglycol (PEG) glue. The implanted microwires showed functionality in acute neural stimulation. When implanted for 1 or 8weeks, the novel soft implants demonstrated significantly reduced inflammatory tissue response at week 8 compared to tungsten wires of similar dimension and surface chemistry. Furthermore, a higher degree of cell body distortion was found next to the tungsten implants compared to the polymer implants. Our results support the use of these novel ultrasoft electrodes for long term neural implants. One critical challenge to the translation of neural recording/stimulation electrode technology to clinically viable devices for brain computer interface (BCI) or deep brain stimulation (DBS) applications is the chronic degradation of device performance due to the inflammatory tissue reaction. While many hypothesize that soft and flexible devices elicit reduced inflammatory tissue responses, there has yet to be a rigorous comparison between soft and stiff implants. We have developed an ultra-soft microelectrode with Young's modulus lower than 1MPa, closely mimicking the brain

  2. Two algorithms for neural-network design and training with application to channel equalization.

    PubMed

    Sweatman, C Z; Mulgrew, B; Gibson, G J

    1998-01-01

    We describe two algorithms for designing and training neural-network classifiers. The first, the linear programming slab algorithm (LPSA), is motivated by the problem of reconstructing digital signals corrupted by passage through a dispersive channel and by additive noise. It constructs a multilayer perceptron (MLP) to separate two disjoint sets by using linear programming methods to identify network parameters. The second, the perceptron learning slab algorithm (PLSA), avoids the computational costs of linear programming by using an error-correction approach to identify parameters. Both algorithms operate in highly constrained parameter spaces and are able to exploit symmetry in the classification problem. Using these algorithms, we develop a number of procedures for the adaptive equalization of a complex linear 4-quadrature amplitude modulation (QAM) channel, and compare their performance in a simulation study. Results are given for both stationary and time-varying channels, the latter based on the COST 207 GSM propagation model.

  3. Envelope Interactions in Multi-Channel Amplitude Modulation Frequency Discrimination by Cochlear Implant Users

    PubMed Central

    2015-01-01

    Rationale Previous cochlear implant (CI) studies have shown that single-channel amplitude modulation frequency discrimination (AMFD) can be improved when coherent modulation is delivered to additional channels. It is unclear whether the multi-channel advantage is due to increased loudness, multiple envelope representations, or to component channels with better temporal processing. Measuring envelope interference may shed light on how modulated channels can be combined. Methods In this study, multi-channel AMFD was measured in CI subjects using a 3-alternative forced-choice, non-adaptive procedure (“which interval is different?”). For the reference stimulus, the reference AM (100 Hz) was delivered to all 3 channels. For the probe stimulus, the target AM (101, 102, 104, 108, 116, 132, 164, 228, or 256 Hz) was delivered to 1 of 3 channels, and the reference AM (100 Hz) delivered to the other 2 channels. The spacing between electrodes was varied to be wide or narrow to test different degrees of channel interaction. Results Results showed that CI subjects were highly sensitive to interactions between the reference and target envelopes. However, performance was non-monotonic as a function of target AM frequency. For the wide spacing, there was significantly less envelope interaction when the target AM was delivered to the basal channel. For the narrow spacing, there was no effect of target AM channel. The present data were also compared to a related previous study in which the target AM was delivered to a single channel or to all 3 channels. AMFD was much better with multiple than with single channels whether the target AM was delivered to 1 of 3 or to all 3 channels. For very small differences between the reference and target AM frequencies (2–4 Hz), there was often greater sensitivity when the target AM was delivered to 1 of 3 channels versus all 3 channels, especially for narrowly spaced electrodes. Conclusions Besides the increased loudness, the present results

  4. Two multichannel integrated circuits for neural recording and signal processing.

    PubMed

    Obeid, Iyad; Morizio, James C; Moxon, Karen A; Nicolelis, Miguel A L; Wolf, Patrick D

    2003-02-01

    We have developed, manufactured, and tested two analog CMOS integrated circuit "neurochips" for recording from arrays of densely packed neural electrodes. Device A is a 16-channel buffer consisting of parallel noninverting amplifiers with a gain of 2 V/V. Device B is a 16-channel two-stage analog signal processor with differential amplification and high-pass filtering. It features selectable gains of 250 and 500 V/V as well as reference channel selection. The resulting amplifiers on Device A had a mean gain of 1.99 V/V with an equivalent input noise of 10 microV(rms). Those on Device B had mean gains of 53.4 and 47.4 dB with a high-pass filter pole at 211 Hz and an equivalent input noise of 4.4 microV(rms). Both devices were tested in vivo with electrode arrays implanted in the somatosensory cortex.

  5. Delayed Rectifier and A-Type Potassium Channels Associated with Kv 2.1 and Kv 4.3 Expression in Embryonic Rat Neural Progenitor Cells

    PubMed Central

    Smith, Dean O.; Rosenheimer, Julie L.; Kalil, Ronald E.

    2008-01-01

    Background Because of the importance of voltage-activated K+ channels during embryonic development and in cell proliferation, we present here the first description of these channels in E15 rat embryonic neural progenitor cells derived from the subventricular zone (SVZ). Activation, inactivation, and single-channel conductance properties of recorded progenitor cells were compared with those obtained by others when these Kv gene products were expressed in oocytes. Methodology/Principal Findings Neural progenitor cells derived from the subventricular zone of E15 embryonic rats were cultured under conditions that did not promote differentiation. Immunocytochemical and Western blot assays for nestin expression indicated that almost all of the cells available for recording expressed this intermediate filament protein, which is generally accepted as a marker for uncommitted embryonic neural progenitor cells. However, a very small numbers of the cells expressed GFAP, a marker for astrocytes, O4, a marker for immature oligodendrocytes, and βIII-tubulin, a marker for neurons. Using immunocytochemistry and Western blots, we detected consistently the expression of Kv2.1, and 4.3. In whole-cell mode, we recorded two outward currents, a delayed rectifier and an A-type current. Conclusions/Significance We conclude that Kv2.1, and 4.3 are expressed in E15 SVZ neural progenitor cells, and we propose that they may be associated with the delayed-rectifier and the A-type currents, respectively, that we recorded. These results demonstrate the early expression of delayed rectifier and A-type K+ currents and channels in embryonic neural progenitor cells prior to the differentiation of these cells. PMID:18270591

  6. Delayed rectifier and A-type potassium channels associated with Kv 2.1 and Kv 4.3 expression in embryonic rat neural progenitor cells.

    PubMed

    Smith, Dean O; Rosenheimer, Julie L; Kalil, Ronald E

    2008-02-13

    Because of the importance of voltage-activated K(+) channels during embryonic development and in cell proliferation, we present here the first description of these channels in E15 rat embryonic neural progenitor cells derived from the subventricular zone (SVZ). Activation, inactivation, and single-channel conductance properties of recorded progenitor cells were compared with those obtained by others when these Kv gene products were expressed in oocytes. Neural progenitor cells derived from the subventricular zone of E15 embryonic rats were cultured under conditions that did not promote differentiation. Immunocytochemical and Western blot assays for nestin expression indicated that almost all of the cells available for recording expressed this intermediate filament protein, which is generally accepted as a marker for uncommitted embryonic neural progenitor cells. However, a very small numbers of the cells expressed GFAP, a marker for astrocytes, O4, a marker for immature oligodendrocytes, and betaIII-tubulin, a marker for neurons. Using immunocytochemistry and Western blots, we detected consistently the expression of Kv2.1, and 4.3. In whole-cell mode, we recorded two outward currents, a delayed rectifier and an A-type current. We conclude that Kv2.1, and 4.3 are expressed in E15 SVZ neural progenitor cells, and we propose that they may be associated with the delayed-rectifier and the A-type currents, respectively, that we recorded. These results demonstrate the early expression of delayed rectifier and A-type K(+) currents and channels in embryonic neural progenitor cells prior to the differentiation of these cells.

  7. Adaptively combined FIR and functional link artificial neural network equalizer for nonlinear communication channel.

    PubMed

    Zhao, Haiquan; Zhang, Jiashu

    2009-04-01

    This paper proposes a novel computational efficient adaptive nonlinear equalizer based on combination of finite impulse response (FIR) filter and functional link artificial neural network (CFFLANN) to compensate linear and nonlinear distortions in nonlinear communication channel. This convex nonlinear combination results in improving the speed while retaining the lower steady-state error. In addition, since the CFFLANN needs not the hidden layers, which exist in conventional neural-network-based equalizers, it exhibits a simpler structure than the traditional neural networks (NNs) and can require less computational burden during the training mode. Moreover, appropriate adaptation algorithm for the proposed equalizer is derived by the modified least mean square (MLMS). Results obtained from the simulations clearly show that the proposed equalizer using the MLMS algorithm can availably eliminate various intensity linear and nonlinear distortions, and be provided with better anti-jamming performance. Furthermore, comparisons of the mean squared error (MSE), the bit error rate (BER), and the effect of eigenvalue ratio (EVR) of input correlation matrix are presented.

  8. Nanofibers implant functionalized by neural growth factor as a strategy to innervate a bioengineered tooth.

    PubMed

    Eap, Sandy; Bécavin, Thibault; Keller, Laetitia; Kökten, Tunay; Fioretti, Florence; Weickert, Jean-Luc; Deveaux, Etienne; Benkirane-Jessel, Nadia; Kuchler-Bopp, Sabine

    2014-03-01

    Current strategies for jaw reconstruction require multiple procedures, to repair the bone defect, to offer sufficient support, and to place the tooth implant. The entire procedure can be painful and time-consuming, and the desired functional repair can be achieved only when both steps are successful. The ability to engineer combined tooth and bone constructs, which would grow in a coordinated fashion with the surrounding tissues, could potentially improve the clinical outcomes and also reduce patient suffering. A unique nanofibrous and active implant for bone-tooth unit regeneration and also the innervation of this bioengineered tooth are demonstrated. A nanofibrous polycaprolactone membrane is functionalized with neural growth factor, along with dental germ, and tooth innervation follows. Such innervation allows complete functionality and tissue homeostasis of the tooth, such as dentinal sensitivity, odontoblast function, masticatory forces, and blood flow. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Ultra-low-power and robust digital-signal-processing hardware for implantable neural interface microsystems.

    PubMed

    Narasimhan, S; Chiel, H J; Bhunia, S

    2011-04-01

    Implantable microsystems for monitoring or manipulating brain activity typically require on-chip real-time processing of multichannel neural data using ultra low-power, miniaturized electronics. In this paper, we propose an integrated-circuit/architecture-level hardware design framework for neural signal processing that exploits the nature of the signal-processing algorithm. First, we consider different power reduction techniques and compare the energy efficiency between the ultra-low frequency subthreshold and conventional superthreshold design. We show that the superthreshold design operating at a much higher frequency can achieve comparable energy dissipation by taking advantage of extensive power gating. It also provides significantly higher robustness of operation and yield under large process variations. Next, we propose an architecture level preferential design approach for further energy reduction by isolating the critical computation blocks (with respect to the quality of the output signal) and assigning them higher delay margins compared to the noncritical ones. Possible delay failures under parameter variations are confined to the noncritical components, allowing graceful degradation in quality under voltage scaling. Simulation results using prerecorded neural data from the sea-slug (Aplysia californica) show that the application of the proposed design approach can lead to significant improvement in total energy, without compromising the output signal quality under process variations, compared to conventional design approaches.

  10. Implanted neural progenitor cells regulate glial reaction to brain injury and establish gap junctions with host glial cells.

    PubMed

    Talaverón, Rocío; Matarredona, Esperanza R; de la Cruz, Rosa R; Macías, David; Gálvez, Victoria; Pastor, Angel M

    2014-04-01

    Transplantation of neural stem/progenitor cells (NPCs) in the lesioned brain is able to restore morphological and physiological alterations induced by different injuries. The local microenvironment created at the site of grafting and the communication between grafted and host cells are crucial in the beneficial effects attributed to the NPC implants. We have previously described that NPC transplantation in an animal model of central axotomy restores firing properties and synaptic coverage of lesioned neurons and modulates their trophic factor content. In this study, we aim to explore anatomical relationships between implanted NPCs and host glia that might account for the implant-induced neuroprotective effects. Postnatal rat subventricular zone NPCs were isolated and grafted in adult rats after transection of the medial longitudinal fascicle. Brains were removed and analyzed eight weeks later. Immunohistochemistry for different glial markers revealed that NPC-grafted animals displayed significantly greater microglial activation than animals that received only vehicle injections. Implanted NPCs were located in close apposition to activated microglia and reactive astrocytes. The gap junction protein connexin43 was present in NPCs and glial cells at the lesion site and was often found interposed within adjacent implanted and glial cells. Gap junctions were identified between implanted NPCs and host astrocytes and less frequently between NPCs and microglia. Our results show that implanted NPCs modulate the glial reaction to lesion and establish the possibility of communication through gap junctions between grafted and host glial cells which might be involved in the restorative effects of NPC implants. Copyright © 2014 Wiley Periodicals, Inc.

  11. Vitamin E isomer δ-tocopherol enhances the efficiency of neural stem cell differentiation via L-type calcium channel.

    PubMed

    Deng, Sihao; Hou, Guoqiang; Xue, Zhiqin; Zhang, Longmei; Zhou, Yuye; Liu, Chao; Liu, Yanqing; Li, Zhiyuan

    2015-01-12

    The effects of the vitamin E isomer δ-tocopherol on neural stem cell (NSC) differentiation have not been investigated until now. Here we investigated the effects of δ-tocopherol on NSC neural differentiation, maturation and its possible mechanisms. Neonatal rat NSCs were grown in suspended neurosphere cultures, and were identified by their expression of nestin protein and their capacity for self-renewal. Treatment with a low concentration of δ-tocopherol induced a significant increase in the percentage of β-III-tubulin-positive cells. δ-Tocopherol also stimulated morphological maturation of neurons in culture. We further observed that δ-tocopherol stimulation increased the expression of voltage-dependent Ca(2+) channels. Moreover, a L-type specific Ca(2+) channel blocker verapamil reduced the percentage of differentiated neurons after δ-tocopherol treatment, and blocked the effects of δ-tocopherol on NSC differentiation into neurons. Together, our study demonstrates that δ-tocopherol may act through elevation of L-type calcium channel activity to increase neuronal differentiation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  12. An array of highly flexible electrodes with a tailored configuration locked by gelatin during implantation-initial evaluation in cortex cerebri of awake rats.

    PubMed

    Agorelius, Johan; Tsanakalis, Fotios; Friberg, Annika; Thorbergsson, Palmi T; Pettersson, Lina M E; Schouenborg, Jens

    2015-01-01

    A major challenge in the field of neural interfaces is to overcome the problem of poor stability of neuronal recordings, which impedes long-term studies of individual neurons in the brain. Conceivably, unstable recordings reflect relative movements between electrode and tissue. To address this challenge, we have developed a new ultra-flexible electrode array and evaluated its performance in awake non-restrained animals. An array of eight separated gold leads (4 × 10 μm), individually flexible in 3D, were cut from a gold sheet using laser milling and insulated with Parylene C. To provide structural support during implantation into rat cortex, the electrode array was embedded in a hard gelatin based material, which dissolves after implantation. Recordings were made during 3 weeks. At termination, the animals were perfused with fixative and frozen to prevent dislocation of the implanted electrodes. A thick slice of brain tissue, with the electrode array still in situ, was made transparent using methyl salicylate to evaluate the conformation of the implanted electrode array. Median noise levels and signal/noise remained relatively stable during the 3 week observation period; 4.3-5.9 μV and 2.8-4.2, respectively. The spike amplitudes were often quite stable within recording sessions and for 15% of recordings where single-units were identified, the highest-SNR unit had an amplitude higher than 150 μV. In addition, high correlations (>0.96) between unit waveforms recorded at different time points were obtained for 58% of the electrode sites. The structure of the electrode array was well preserved 3 weeks after implantation. A new implantable multichannel neural interface, comprising electrodes individually flexible in 3D that retain its architecture and functionality after implantation has been developed. Since the new neural interface design is adaptable, it offers a versatile tool to explore the function of various brain structures.

  13. An ovine model of cerebral catheter venography for implantation of an endovascular neural interface.

    PubMed

    Oxley, Thomas James; Opie, Nicholas Lachlan; Rind, Gil Simon; Liyanage, Kishan; John, Sam Emmanuel; Ronayne, Stephen; McDonald, Alan James; Dornom, Anthony; Lovell, Timothy John Haynes; Mitchell, Peter John; Bennett, Iwan; Bauquier, Sebastien; Warne, Leon Norris; Steward, Chris; Grayden, David Bruce; Desmond, Patricia; Davis, Stephen M; O'Brien, Terence John; May, Clive N

    2018-04-01

    OBJECTIVE Neural interface technology may enable the development of novel therapies to treat neurological conditions, including motor prostheses for spinal cord injury. Intracranial neural interfaces currently require a craniotomy to achieve implantation and may result in chronic tissue inflammation. Novel approaches are required that achieve less invasive implantation methods while maintaining high spatial resolution. An endovascular stent electrode array avoids direct brain trauma and is able to record electrocorticography in local cortical tissue from within the venous vasculature. The motor area in sheep runs in a parasagittal plane immediately adjacent to the superior sagittal sinus (SSS). The authors aimed to develop a sheep model of cerebral venography that would enable validation of an endovascular neural interface. METHODS Cerebral catheter venography was performed in 39 consecutive sheep. Contrast-enhanced MRI of the brain was performed on 13 animals. Multiple telescoping coaxial catheter systems were assessed to determine the largest wide-bore delivery catheter that could be delivered into the anterior SSS. Measurements of SSS diameter and distance from the motor area were taken. The location of the motor area was determined in relation to lateral and superior projections of digital subtraction venography images and confirmed on MRI. RESULTS The venous pathway from the common jugular vein (7.4 mm) to the anterior SSS (1.2 mm) was technically challenging to selectively catheterize. The SSS coursed immediately adjacent to the motor cortex (< 1 mm) for a length of 40 mm, or the anterior half of the SSS. Attempted access with 5-Fr and 6-Fr delivery catheters was associated with longer procedure times and higher complication rates. A 4-Fr catheter (internal lumen diameter 1.1 mm) was successful in accessing the SSS in 100% of cases with no associated complications. Complications included procedure-related venous dissection in two major areas: the torcular

  14. Effect of Healing Time on Bone-Implant Contact of Orthodontic Micro-Implants: A Histologic Study

    PubMed Central

    Ramazanzadeh, Barat Ali; Fatemi, Kazem; Dehghani, Mahboobe; Mohtasham, Nooshin; Jahanbin, Arezoo; Sadeghian, Hamed

    2014-01-01

    Objectives. This study aimed to evaluate the effect of immediate and delayed loading of orthodontic micro-implants on bone-implant contact. Materials and Methods. Sixty four micro-implants were implanted in dog's jaw bone. The micro-implants were divided into loaded and unloaded (control) groups. The control group had two subgroups: four and eight weeks being implanted. The loaded group had two subgroups of immediate loading and delayed (after four weeks healing) loading. Loaded samples were subjected to 200g load for four weeks. After sacrificing the animals micro-implants and surrounding tissues were observed histologically. Bone-implant contact ratios (BIC) were calculated and different groups' results were compared by three-way ANOVA. Results. Mean survival rate was 96.7% in general. Survival rates were 96.7%, 94.4% and 100% for control, immediate and delayed loaded groups, respectively. BIC values were not significantly different in loaded and control groups, immediate and delayed loading groups, and pressure and tension sides. Mandibular micro-implants had significantly higher BIC than maxillary ones in immediate loading, 4-weeks control, and 8-weeks control groups (P = 0.021, P = 0.009, P = 0.003, resp.). Conclusion Immediate or delayed loading of micro-implants in dog did not cause significant difference in Bone-implant contact which could be concluded that healing time had not significant effect on micro-implant stability. PMID:25006463

  15. Effect of healing time on bone-implant contact of orthodontic micro-implants: a histologic study.

    PubMed

    Ramazanzadeh, Barat Ali; Fatemi, Kazem; Dehghani, Mahboobe; Mohtasham, Nooshin; Jahanbin, Arezoo; Sadeghian, Hamed

    2014-01-01

    Objectives. This study aimed to evaluate the effect of immediate and delayed loading of orthodontic micro-implants on bone-implant contact. Materials and Methods. Sixty four micro-implants were implanted in dog's jaw bone. The micro-implants were divided into loaded and unloaded (control) groups. The control group had two subgroups: four and eight weeks being implanted. The loaded group had two subgroups of immediate loading and delayed (after four weeks healing) loading. Loaded samples were subjected to 200g load for four weeks. After sacrificing the animals micro-implants and surrounding tissues were observed histologically. Bone-implant contact ratios (BIC) were calculated and different groups' results were compared by three-way ANOVA. Results. Mean survival rate was 96.7% in general. Survival rates were 96.7%, 94.4% and 100% for control, immediate and delayed loaded groups, respectively. BIC values were not significantly different in loaded and control groups, immediate and delayed loading groups, and pressure and tension sides. Mandibular micro-implants had significantly higher BIC than maxillary ones in immediate loading, 4-weeks control, and 8-weeks control groups (P = 0.021, P = 0.009, P = 0.003, resp.). Conclusion Immediate or delayed loading of micro-implants in dog did not cause significant difference in Bone-implant contact which could be concluded that healing time had not significant effect on micro-implant stability.

  16. [Endo-exo prostheses : Osseointegrated percutaneously channeled implants for rehabilitation after limb amputation].

    PubMed

    Aschoff, H-H; Juhnke, D-L

    2016-05-01

    In 1999 the first endo-exo femoral prosthesis (EEFP) was implanted in Germany in a patient who had suffered a traumatic above-knee amputation. This procedure involves a skeletally anchored exoprosthetic device that is inserted into the residual femur. The distal part of the implant protrudes transcutaneously and allows attachment to a prosthetic limb which provides direct force transmission to the external prosthetic components. The technique originated from dental implantology and helps to avoid possible problems resulting from treatment of amputated limbs using socket prostheses. In the meantime, durability times of over 10 years have now helped to invalidate the initially well-founded reservations held against the procedure. What advantages can be achieved by osseointegrated and percutaneously channeled prostheses and which problems had to be overcome for treatment. Critical evaluation of data from patients operated on in Lübeck, Germany from January 2003 to December 2014. With osseointegrated and percutaneously channeled prostheses permanent durability times can be achieved. Infection-associated soft tissue problems at the site of skin protrusion (stoma) can be successfully prevented. The creation of this so-called stoma means acceptance of a possible bacterial portal of entry into the body. Patient satisfaction has so far been high, postoperative rehabilitation is simplified and the technique could possibly lower the costs of medical treatment. Endo-exo prostheses have proved to be successful for more than 15 years. A critical appraisal of the indications as well as a close cooperation between the surgeon, orthopedic technician and the associated rehabilitation facilities with the patient are the basis for the long-term success of this relatively new treatment approach.

  17. EDITORIAL: Focus on the neural interface Focus on the neural interface

    NASA Astrophysics Data System (ADS)

    Durand, Dominique M.

    2009-10-01

    The possibility of an effective connection between neural tissue and computers has inspired scientists and engineers to develop new ways of controlling and obtaining information from the nervous system. These applications range from `brain hacking' to neural control of artificial limbs with brain signals. Notwithstanding the significant advances in neural prosthetics in the last few decades and the success of some stimulation devices such as cochlear prosthesis, neurotechnology remains below its potential for restoring neural function in patients with nervous system disorders. One of the reasons for this limited impact can be found at the neural interface and close attention to the integration between electrodes and tissue should improve the possibility of successful outcomes. The neural interfaces research community consists of investigators working in areas such as deep brain stimulation, functional neuromuscular/electrical stimulation, auditory prostheses, cortical prostheses, neuromodulation, microelectrode array technology, brain-computer/machine interfaces. Following the success of previous neuroprostheses and neural interfaces workshops, funding (from NIH) was obtained to establish a biennial conference in the area of neural interfaces. The first Neural Interfaces Conference took place in Cleveland, OH in 2008 and several topics from this conference have been selected for publication in this special section of the Journal of Neural Engineering. Three `perspectives' review the areas of neural regeneration (Corredor and Goldberg), cochlear implants (O'Leary et al) and neural prostheses (Anderson). Seven articles focus on various aspects of neural interfacing. One of the most popular of these areas is the field of brain-computer interfaces. Fraser et al, report on a method to generate robust control with simple signal processing algorithms of signals obtained with electrodes implanted in the brain. One problem with implanted electrode arrays, however, is that

  18. [The application of artificial neural network on the assessment of lexical tone production of pediatric cochlear implant users].

    PubMed

    Mao, Y T; Chen, Z M; Xu, L

    2017-08-07

    Objective: The present study was carried out to explore the tone production ability of the Mandarin-speaking children with cochlear implants (CI) by using an artificial neural network model and to examine the potential contributing factors underlining their tone production performance. The results of this study might provide useful guidelines for post-operative rehabilitation processes of pediatric CI users. Methods: Two hundred and seventy-eight prelingually deafened children who received unilateral CI participated in this study. As controls, 170 similarly-aged children with normal hearing (NH) were recruited. A total of 36 Chinese monosyllabic words were selected as the tone production targets. Vocal production samples were recorded and the fundamental frequency (F0) contour of each syllable was extracted using an auto-correlation algorithm followed by manual correction. An artificial neural network was created in MATLAB to classify the tone production. The relationships between tone production and several demographic factors were evaluated. Results: Pediatric CI users produced Mandarin tones much less accurately than did the NH children (58.8% vs. 91.5% correct). Tremendous variability in tone production performance existed among the CI children. Tones 2 and 3 were produced less accurately than tones 1 and 4 for both groups. For the CI group, all tones when in error tended to be judged as tone 1. The tone production accuracy was negatively correlated with age at implantation and positively correlated with CI use duration with correlation coefficients ( r ) of -0.215 ( P =0.003) and 0.203 ( P =0.005), respectively. Age was one of the determinants of tonal ability for NH children. Conclusions: For children with severe to profound hearing loss, early implantation and persistent use of CI are beneficial to their tone production development. Artificial neural network is a convenient and reliable assessment tool for the development of tonal ability of hearing

  19. Reach and grasp by people with tetraplegia using a neurally controlled robotic arm

    PubMed Central

    Hochberg, Leigh R.; Bacher, Daniel; Jarosiewicz, Beata; Masse, Nicolas Y.; Simeral, John D.; Vogel, Joern; Haddadin, Sami; Liu, Jie; Cash, Sydney S.; van der Smagt, Patrick; Donoghue, John P.

    2012-01-01

    Paralysis following spinal cord injury (SCI), brainstem stroke, amyotrophic lateral sclerosis (ALS) and other disorders can disconnect the brain from the body, eliminating the ability to carry out volitional movements. A neural interface system (NIS)1–5 could restore mobility and independence for people with paralysis by translating neuronal activity directly into control signals for assistive devices. We have previously shown that people with longstanding tetraplegia can use an NIS to move and click a computer cursor and to control physical devices6–8. Able-bodied monkeys have used an NIS to control a robotic arm9, but it is unknown whether people with profound upper extremity paralysis or limb loss could use cortical neuronal ensemble signals to direct useful arm actions. Here, we demonstrate the ability of two people with long-standing tetraplegia to use NIS-based control of a robotic arm to perform three-dimensional reach and grasp movements. Participants controlled the arm over a broad space without explicit training, using signals decoded from a small, local population of motor cortex (MI) neurons recorded from a 96-channel microelectrode array. One of the study participants, implanted with the sensor five years earlier, also used a robotic arm to drink coffee from a bottle. While robotic reach and grasp actions were not as fast or accurate as those of an able-bodied person, our results demonstrate the feasibility for people with tetraplegia, years after CNS injury, to recreate useful multidimensional control of complex devices directly from a small sample of neural signals. PMID:22596161

  20. Cortical activation patterns correlate with speech understanding after cochlear implantation

    PubMed Central

    Olds, Cristen; Pollonini, Luca; Abaya, Homer; Larky, Jannine; Loy, Megan; Bortfeld, Heather; Beauchamp, Michael S.; Oghalai, John S.

    2015-01-01

    Objectives Cochlear implants are a standard therapy for deafness, yet the ability of implanted patients to understand speech varies widely. To better understand this variability in outcomes, we used functional near-infrared spectroscopy (fNIRS) to image activity within regions of the auditory cortex and compare the results to behavioral measures of speech perception. Design We studied 32 deaf adults hearing through cochlear implants and 35 normal-hearing controls. We used fNIRS to measure responses within the lateral temporal lobe and the superior temporal gyrus to speech stimuli of varying intelligibility. The speech stimuli included normal speech, channelized speech (vocoded into 20 frequency bands), and scrambled speech (the 20 frequency bands were shuffled in random order). We also used environmental sounds as a control stimulus. Behavioral measures consisted of the Speech Reception Threshold, CNC words, and AzBio Sentence tests measured in quiet. Results Both control and implanted participants with good speech perception exhibited greater cortical activations to natural speech than to unintelligible speech. In contrast, implanted participants with poor speech perception had large, indistinguishable cortical activations to all stimuli. The ratio of cortical activation to normal speech to that of scrambled speech directly correlated with the CNC Words and AzBio Sentences scores. This pattern of cortical activation was not correlated with auditory threshold, age, side of implantation, or time after implantation. Turning off the implant reduced cortical activations in all implanted participants. Conclusions Together, these data indicate that the responses we measured within the lateral temporal lobe and the superior temporal gyrus correlate with behavioral measures of speech perception, demonstrating a neural basis for the variability in speech understanding outcomes after cochlear implantation. PMID:26709749

  1. A low-cost, scalable, current-sensing digital headstage for high channel count μECoG.

    PubMed

    Trumpis, Michael; Insanally, Michele; Zou, Jialin; Elsharif, Ashraf; Ghomashchi, Ali; Sertac Artan, N; Froemke, Robert C; Viventi, Jonathan

    2017-04-01

    High channel count electrode arrays allow for the monitoring of large-scale neural activity at high spatial resolution. Implantable arrays featuring many recording sites require compact, high bandwidth front-end electronics. In the present study, we investigated the use of a small, light weight, and low cost digital current-sensing integrated circuit for acquiring cortical surface signals from a 61-channel micro-electrocorticographic (μECoG) array. We recorded both acute and chronic μECoG signal from rat auditory cortex using our novel digital current-sensing headstage. For direct comparison, separate recordings were made in the same anesthetized preparations using an analog voltage headstage. A model of electrode impedance explained the transformation between current- and voltage-sensed signals, and was used to reconstruct cortical potential. We evaluated the digital headstage using several metrics of the baseline and response signals. The digital current headstage recorded neural signal with similar spatiotemporal statistics and auditory frequency tuning compared to the voltage signal. The signal-to-noise ratio of auditory evoked responses (AERs) was significantly stronger in the current signal. Stimulus decoding based on true and reconstructed voltage signals were not significantly different. Recordings from an implanted system showed AERs that were detectable and decodable for 52 d. The reconstruction filter mitigated the thermal current noise of the electrode impedance and enhanced overall SNR. We developed and validated a novel approach to headstage acquisition that used current-input circuits to independently digitize 61 channels of μECoG measurements of the cortical field. These low-cost circuits, intended to measure photo-currents in digital imaging, not only provided a signal representing the local cortical field with virtually the same sensitivity and specificity as a traditional voltage headstage but also resulted in a small, light headstage that can

  2. A low-cost, scalable, current-sensing digital headstage for high channel count μECoG

    NASA Astrophysics Data System (ADS)

    Trumpis, Michael; Insanally, Michele; Zou, Jialin; Elsharif, Ashraf; Ghomashchi, Ali; Sertac Artan, N.; Froemke, Robert C.; Viventi, Jonathan

    2017-04-01

    Objective. High channel count electrode arrays allow for the monitoring of large-scale neural activity at high spatial resolution. Implantable arrays featuring many recording sites require compact, high bandwidth front-end electronics. In the present study, we investigated the use of a small, light weight, and low cost digital current-sensing integrated circuit for acquiring cortical surface signals from a 61-channel micro-electrocorticographic (μECoG) array. Approach. We recorded both acute and chronic μECoG signal from rat auditory cortex using our novel digital current-sensing headstage. For direct comparison, separate recordings were made in the same anesthetized preparations using an analog voltage headstage. A model of electrode impedance explained the transformation between current- and voltage-sensed signals, and was used to reconstruct cortical potential. We evaluated the digital headstage using several metrics of the baseline and response signals. Main results. The digital current headstage recorded neural signal with similar spatiotemporal statistics and auditory frequency tuning compared to the voltage signal. The signal-to-noise ratio of auditory evoked responses (AERs) was significantly stronger in the current signal. Stimulus decoding based on true and reconstructed voltage signals were not significantly different. Recordings from an implanted system showed AERs that were detectable and decodable for 52 d. The reconstruction filter mitigated the thermal current noise of the electrode impedance and enhanced overall SNR. Significance. We developed and validated a novel approach to headstage acquisition that used current-input circuits to independently digitize 61 channels of μECoG measurements of the cortical field. These low-cost circuits, intended to measure photo-currents in digital imaging, not only provided a signal representing the local cortical field with virtually the same sensitivity and specificity as a traditional voltage headstage but

  3. A low-cost, scalable, current-sensing digital headstage for high channel count μECoG

    PubMed Central

    Trumpis, Michael; Insanally, Michele; Zou, Jialin; Elsharif, Ashraf; Ghomashchi, Ali; Artan, N. Sertac; Froemke, Robert C.; Viventi, Jonathan

    2017-01-01

    Objective High channel count electrode arrays allow for the monitoring of large-scale neural activity at high spatial resolution. Implantable arrays featuring many recording sites require compact, high bandwidth front-end electronics. In the present study, we investigated the use of a small, light weight, and low cost digital current-sensing integrated circuit for acquiring cortical surface signals from a 61-channel micro-electrocorticographic (μECoG) array. Approach We recorded both acute and chronic μECoG signal from rat auditory cortex using our novel digital current-sensing headstage. For direct comparison, separate recordings were made in the same anesthetized preparations using an analog voltage headstage. A model of electrode impedance explained the transformation between current- and voltage-sensed signals, and was used to reconstruct cortical potential. We evaluated the digital headstage using several metrics of the baseline and response signals. Main results The digital current headstage recorded neural signal with similar spatiotemporal statistics and auditory frequency tuning compared to the voltage signal. The signal-to-noise ratio of auditory evoked responses (AERs) was significantly stronger in the current signal. Stimulus decoding based on true and reconstructed voltage signals were not significantly different. Recordings from an implanted system showed AERs that were detectable and decodable for 52 days. The reconstruction filter mitigated the thermal current noise of the electrode impedance and enhanced overall SNR. Significance We developed and validated a novel approach to headstage acquisition that used current-input circuits to independently digitize 61 channels of μECoG measurements of the cortical field. These low-cost circuits, intended to measure photo-currents in digital imaging, not only provided a signal representing the local cortical field with virtually the same sensitivity and specificity as a traditional voltage headstage but

  4. Neural progenitor cell implants modulate vascular endothelial growth factor and brain-derived neurotrophic factor expression in rat axotomized neurons.

    PubMed

    Talaverón, Rocío; Matarredona, Esperanza R; de la Cruz, Rosa R; Pastor, Angel M

    2013-01-01

    Axotomy of central neurons leads to functional and structural alterations which largely revert when neural progenitor cells (NPCs) are implanted in the lesion site. The new microenvironment created by NPCs in the host tissue might modulate in the damaged neurons the expression of a high variety of molecules with relevant roles in the repair mechanisms, including neurotrophic factors. In the present work, we aimed to analyze changes in neurotrophic factor expression in axotomized neurons induced by NPC implants. For this purpose, we performed immunofluorescence followed by confocal microscopy analysis for the detection of vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and nerve growth factor (NGF) on brainstem sections from rats with axotomy of abducens internuclear neurons that received NPC implants (implanted group) or vehicle injections (axotomized group) in the lesion site. Control abducens internuclear neurons were strongly immunoreactive to VEGF and BDNF but showed a weak staining for NT-3 and NGF. Comparisons between groups revealed that lesioned neurons from animals that received NPC implants showed a significant increase in VEGF content with respect to animals receiving vehicle injections. However, the immunoreactivity for BDNF, which was increased in the axotomized group as compared to control, was not modified in the implanted group. The modifications induced by NPC implants on VEGF and BDNF content were specific for the population of axotomized abducens internuclear neurons since the neighboring abducens motoneurons were not affected. Similar levels of NT-3 and NGF immunolabeling were obtained in injured neurons from axotomized and implanted animals. Among all the analyzed neurotrophic factors, only VEGF was expressed by the implanted cells in the lesion site. Our results point to a role of NPC implants in the modulation of neurotrophic factor expression by lesioned central neurons, which might

  5. A low-power current-reuse dual-band analog front-end for multi-channel neural signal recording.

    PubMed

    Sepehrian, H; Gosselin, B

    2014-01-01

    Thoroughly studying the brain activity of freely moving subjects requires miniature data acquisition systems to measure and wirelessly transmit neural signals in real time. In this application, it is mandatory to simultaneously record the bioelectrical activity of a large number of neurons to gain a better knowledge of brain functions. However, due to limitations in transferring the entire raw data to a remote base station, employing dedicated data reduction techniques to extract the relevant part of neural signals is critical to decrease the amount of data to transfer. In this work, we present a new dual-band neural amplifier to separate the neuronal spike signals (SPK) and the local field potential (LFP) simultaneously in the analog domain, immediately after the pre-amplification stage. By separating these two bands right after the pre-amplification stage, it is possible to process LFP and SPK separately. As a result, the required dynamic range of the entire channel, which is determined by the signal-to-noise ratio of the SPK signal of larger bandwidth, can be relaxed. In this design, a new current-reuse low-power low-noise amplifier and a new dual-band filter that separates SPK and LFP while saving capacitors and pseudo resistors. A four-channel dual-band (SPK, LFP) analog front-end capable of simultaneously separating SPK and LFP is implemented in a TSMC 0.18 μm technology. Simulation results present a total power consumption per channel of 3.1 μw for an input referred noise of 3.28 μV and a NEF for 2.07. The cutoff frequency of the LFP band is fc=280 Hz, and fL=725 Hz and fL=11.2 KHz for SPK, with 36 dB gain for LFP band 46 dB gain for SPK band.

  6. Effect of modifying the screw access channels of zirconia implant abutment on the cement flow pattern and retention of zirconia restorations.

    PubMed

    Wadhwani, Chandur; Chung, Kwok-Hung

    2014-07-01

    The effect of managing the screw access channels of zirconia implant abutments in the esthetic zone has not been extensively evaluated. The purpose of this study was to determine the effect of an insert placed within the screw access channel of an anterior zirconia implant abutment on the amount of cement retained within the restoration-abutment system and on the dislodging force. Thirty-six paired zirconia abutments and restorations were fabricated by computer-aided design and computer-aided manufacturing and were divided into 3 groups: open abutment, with the screw access channel unfilled; closed abutment, with the screw access channel sealed; and insert abutment, with a thin, tubular metal insert projection continuous with the screw head and placed into the abutment screw access channel. The restorations were cemented to the abutments with preweighed eugenol-free zinc oxide cement (TempBond NE). Excess cement was removed, and the weight of the cement that remained in the restoration-abutment system was measured. Vertical tensile dislodging forces were recorded at a crosshead speed of 5 mm/min after incubation in a 37°C water bath for 24 hours. The specimens were examined for the cement flow pattern into the screw access channel after dislodgement. Data were analyzed with ANOVA, followed by multiple comparisons by using the Tukey honestly significant difference test (α = .05). The mean (standard deviation) of retentive force values ranged from 108.1 ± 29.9 N to 148.3 ± 21.0 N. The retentive force values differed significantly between the insert abutment and both the open abutment (P < .05) and closed abutment groups (P < .01). Distinct patterns of cement failure were noted. The weight of the cement that remained in the system differed significantly, with both open abutment and insert abutment being greater than closed abutment (P < .05). Modifying the internal configuration of the screw access channel of an esthetic zirconia implant abutment with a metal

  7. Mechanical and Biological Interactions of Implants with the Brain and Their Impact on Implant Design

    PubMed Central

    Prodanov, Dimiter; Delbeke, Jean

    2016-01-01

    Neural prostheses have already a long history and yet the cochlear implant remains the only success story about a longterm sensory function restoration. On the other hand, neural implants for deep brain stimulation are gaining acceptance for variety of disorders including Parkinsons disease and obsessive-compulsive disorder. It is anticipated that the progress in the field has been hampered by a combination of technological and biological factors, such as the limited understanding of the longterm behavior of implants, unreliability of devices, biocompatibility of the implants among others. While the field's understanding of the cell biology of interactions at the biotic-abiotic interface has improved, relatively little attention has been paid on the mechanical factors (stress, strain), and hence on the geometry that can modulate it. This focused review summarizes the recent progress in the understanding of the mechanisms of mechanical interaction between the implants and the brain. The review gives an overview of the factors by which the implants interact acutely and chronically with the tissue: blood-brain barrier (BBB) breach, vascular damage, micromotions, diffusion etc. We propose some design constraints to be considered in future studies. Aspects of the chronic cell-implant interaction will be discussed in view of the chronic local inflammation and the ways of modulating it. PMID:26903786

  8. Linear-phase delay filters for ultra-low-power signal processing in neural recording implants.

    PubMed

    Gosselin, Benoit; Sawan, Mohamad; Kerherve, Eric

    2010-06-01

    We present the design and implementation of linear-phase delay filters for ultra-low-power signal processing in neural recording implants. We use these filters as low-distortion delay elements along with an automatic biopotential detector to perform integral waveform extraction and efficient power management. The presented delay elements are realized employing continuous-time OTA-C filters featuring 9th-order equiripple transfer functions with constant group delay. Such analog delay enables processing neural waveforms with reduced overhead compared to a digital delay since it does not requires sampling and digitization. It uses an allpass transfer function for achieving wider constant-delay bandwidth than all-pole does. Two filters realizations are compared for implementing the delay element: the Cascaded structure and the Inverse follow-the-leader feedback filter. Their respective strengths and drawbacks are assessed by modeling parasitics and non-idealities of OTAs, and by transistor-level simulations. A budget of 200 nA is used in both filters. Experimental measurements with the chosen filter topology are presented and discussed.

  9. Hydroxyapatite implants with designed internal architecture.

    PubMed

    Chu, T M; Halloran, J W; Hollister, S J; Feinberg, S E

    2001-06-01

    Porous hydroxyapatite (HA) has been used as a bone graft material in the clinics for decades. Traditionally, the pores in these HAs are either obtained from the coralline exoskeletal patterns or from the embedded organic particles in the starting HA powder. Both processes offer very limited control on the pore structure. A new method for manufacturing porous HA with designed pore channels has been developed. This method is essentially a lost-mold technique with negative molds made with Stereolithography and a highly loaded curable HA suspension as the ceramic carrier. Implants with designed channels and connection patterns were first generated from a Computer-Aided-Design (CAD) software and Computer Tomography (CT) data. The negative images of the designs were used to build the molds on a stereolithography apparatus with epoxy resins. A 40 vol% HA suspension in propoxylated neopentyl glycol diacrylate (PNPGDA) and iso-bornyl acrylate (IBA) was formulated. HA suspension was cast into the epoxy molds and cured into solid at 85 degrees C. The molds and acrylate binders were removed by pyrolysis, followed by HA green body sintering. With this method, implants with six different channel designs were built successfully and the designed channels were reproduced in the sintered HA implants. The channels created in the sintered HA implants were between 366 microm and 968 microm in diameter with standard deviations of 50 microm or less. The porosity created by the channels were between 26% and 52%. The results show that HA implants with designed connection pattern and well controlled channel size can be built with the technique developed in this study. Copyright 2001 Kluwer Academic Publishers

  10. A wireless multi-channel recording system for freely behaving mice and rats.

    PubMed

    Fan, David; Rich, Dylan; Holtzman, Tahl; Ruther, Patrick; Dalley, Jeffrey W; Lopez, Alberto; Rossi, Mark A; Barter, Joseph W; Salas-Meza, Daniel; Herwik, Stanislav; Holzhammer, Tobias; Morizio, James; Yin, Henry H

    2011-01-01

    To understand the neural basis of behavior, it is necessary to record brain activity in freely moving animals. Advances in implantable multi-electrode array technology have enabled researchers to record the activity of neuronal ensembles from multiple brain regions. The full potential of this approach is currently limited by reliance on cable tethers, with bundles of wires connecting the implanted electrodes to the data acquisition system while impeding the natural behavior of the animal. To overcome these limitations, here we introduce a multi-channel wireless headstage system designed for small animals such as rats and mice. A variety of single unit and local field potential signals were recorded from the dorsal striatum and substantia nigra in mice and the ventral striatum and prefrontal cortex simultaneously in rats. This wireless system could be interfaced with commercially available data acquisition systems, and the signals obtained were comparable in quality to those acquired using cable tethers. On account of its small size, light weight, and rechargeable battery, this wireless headstage system is suitable for studying the neural basis of natural behavior, eliminating the need for wires, commutators, and other limitations associated with traditional tethered recording systems.

  11. A Wireless Multi-Channel Recording System for Freely Behaving Mice and Rats

    PubMed Central

    Holtzman, Tahl; Ruther, Patrick; Dalley, Jeffrey W.; Lopez, Alberto; Rossi, Mark A.; Barter, Joseph W.; Salas-Meza, Daniel; Herwik, Stanislav; Holzhammer, Tobias; Morizio, James; Yin, Henry H.

    2011-01-01

    To understand the neural basis of behavior, it is necessary to record brain activity in freely moving animals. Advances in implantable multi-electrode array technology have enabled researchers to record the activity of neuronal ensembles from multiple brain regions. The full potential of this approach is currently limited by reliance on cable tethers, with bundles of wires connecting the implanted electrodes to the data acquisition system while impeding the natural behavior of the animal. To overcome these limitations, here we introduce a multi-channel wireless headstage system designed for small animals such as rats and mice. A variety of single unit and local field potential signals were recorded from the dorsal striatum and substantia nigra in mice and the ventral striatum and prefrontal cortex simultaneously in rats. This wireless system could be interfaced with commercially available data acquisition systems, and the signals obtained were comparable in quality to those acquired using cable tethers. On account of its small size, light weight, and rechargeable battery, this wireless headstage system is suitable for studying the neural basis of natural behavior, eliminating the need for wires, commutators, and other limitations associated with traditional tethered recording systems. PMID:21765934

  12. Reliability of spring interconnects for high channel-count polyimide electrode arrays

    NASA Astrophysics Data System (ADS)

    Khan, Sharif; Ordonez, Juan Sebastian; Stieglitz, Thomas

    2018-05-01

    Active neural implants with a high channel-count need robust and reliable operational assembly for the targeted environment in order to be classified as viable fully implantable systems. The discrete functionality of the electrode array and the implant electronics is vital for intact assembly. A critical interface exists at the interconnection sites between the electrode array and the implant electronics, especially in hybrid assemblies (e.g. retinal implants) where electrodes and electronics are not on the same substrate. Since the interconnects in such assemblies cannot be hermetically sealed, reliable protection against the physiological environment is essential for delivering high insulation resistance and low defusibility of salt ions, which are limited in complexity by current assembly techniques. This work reports on a combination of spring-type interconnects on a polyimide array with silicone rubber gasket insulation for chronically active implantable systems. The spring design of the interconnects on the backend of the electrode array compensates for the uniform thickness of the sandwiched gasket during bonding in assembly and relieves the propagation of extrinsic stresses to the bulk polyimide substrate. The contact resistance of the microflex-bonded spring interconnects with the underlying metallized ceramic test vehicles and insulation through the gasket between adjacent contacts was investigated against the MIL883 standard. The contact and insulation resistances remained stable in the exhausting environmental conditions.

  13. Materials and technologies for soft implantable neuroprostheses

    NASA Astrophysics Data System (ADS)

    Lacour, Stéphanie P.; Courtine, Grégoire; Guck, Jochen

    2016-10-01

    Implantable neuroprostheses are engineered systems designed to restore or substitute function for individuals with neurological deficits or disabilities. These systems involve at least one uni- or bidirectional interface between a living neural tissue and a synthetic structure, through which information in the form of electrons, ions or photons flows. Despite a few notable exceptions, the clinical dissemination of implantable neuroprostheses remains limited, because many implants display inconsistent long-term stability and performance, and are ultimately rejected by the body. Intensive research is currently being conducted to untangle the complex interplay of failure mechanisms. In this Review, we emphasize the importance of minimizing the physical and mechanical mismatch between neural tissues and implantable interfaces. We explore possible materials solutions to design and manufacture neurointegrated prostheses, and outline their immense therapeutic potential.

  14. Short Implants Versus Standard Implants: Midterm Outcomes of a Clinical Study.

    PubMed

    Benlidayi, M Emre; Ucar, Yurdanur; Tatli, Ufuk; Ekren, Orhun; Evlice, Burcu; Kisa, Halil Ibrahim; Baksi, Uygar

    2018-02-01

    The aim of this study was to evaluate the midterm survival rate, marginal bone resorption (MBR), and stability of short implants and to compare the results with standard length implants. A total of 38 patients were included. In total, 147 implants (Nucleoss Implants, Izmir, Turkey) were placed (86 short implants and 61 standard implants). Cement-retained metal-ceramic prostheses were fabricated. MBR was evaluated on periapical radiographs taken at implant placement, at the time of crown insertion and annually thereafter. The stability of the implants was evaluated by resonance frequency analysis. The 3- and 5-year cumulative survival rates for standard implants was 98.4% and for short implants was 96.5% (P = 0.644). The MBR of the short implants was significantly lower than that of the standard implants after 1, 2, and 3 years of loading (P < 0.05). No significant differences were found between 2 groups after 6 and 12 months of loading in terms of implant stability (implant stability quotient values) (P > 0.05). Within the limits of this study, it is concluded that short implants achieved similar results as standard implants after 3 to 5 years of loading.

  15. A Wirelessly Powered Micro-Spectrometer for Neural Probe-Pin Device

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Kim, Min Hyuck; Song, Kyo D.; Yoon, Hargsoon; Lee, Uhn

    2015-01-01

    Treatment of neurological anomalies, places stringent demands on device functionality and size. A micro-spectrometer has been developed for use as an implantable neural probe to monitor neuro-chemistry in synapses. The microspectrometer, based on a NASA-invented miniature Fresnel grating, is capable of differentiating the emission spectra from various brain tissues. The micro-spectrometer meets the size requirements, and is able to probe the neuro-chemistry and suppression voltage typically associated with a neural anomaly. This neural probe-pin device (PPD) is equipped with wireless power technology (WPT) enabling operation in a continuous manner without requiring an implanted battery. The implanted neural PPD, together with a neural electronics interface and WPT, allow real-time measurement and control/feedback for remediation of neural anomalies. The design and performance of the combined PPD/WPT device for monitoring dopamine in a rat brain will be presented to demonstrate the current level of development. Future work on this device will involve the addition of an embedded expert system capable of performing semi-autonomous management of neural functions through a routine of sensing, processing, and control.

  16. A wirelessly powered microspectrometer for neural probe-pin device

    NASA Astrophysics Data System (ADS)

    Choi, Sang H.; Kim, Min H.; Song, Kyo D.; Yoon, Hargsoon; Lee, Uhn

    2015-12-01

    Treatment of neurological anomalies, whether done invasively or not, places stringent demands on device functionality and size. We have developed a micro-spectrometer for use as an implantable neural probe to monitor neuro-chemistry in synapses. The micro-spectrometer, based on a NASA-invented miniature Fresnel grating, is capable of differentiating the emission spectra from various brain tissues. The micro-spectrometer meets the size requirements, and is able to probe the neuro-chemistry and suppression voltage typically associated with a neural anomaly. This neural probe-pin device (PPD) is equipped with wireless power technology (WPT) to enable operation in a continuous manner without requiring an implanted battery. The implanted neural PPD, together with a neural electronics interface and WPT, enable real-time measurement and control/feedback for remediation of neural anomalies. The design and performance of the combined PPD/WPT device for monitoring dopamine in a rat brain will be presented to demonstrate the current level of development. Future work on this device will involve the addition of an embedded expert system capable of performing semi-autonomous management of neural functions through a routine of sensing, processing, and control.

  17. Multiple Channel Bridges for Spinal Cord Injury: Cellular Characterization of Host Response

    PubMed Central

    Yang, Yang; Laporte, Laura De; Zelivyanskaya, Marina L.; Whittlesey, Kevin J.; Anderson, Aileen J.; Cummings, Brian J.

    2009-01-01

    Bridges for treatment of the injured spinal cord must stabilize the injury site to prevent secondary damage and create a permissive environment that promotes regeneration. The host response to the bridge is central to creating a permissive environment, as the cell types that respond to the injury have the potential to secrete both stimulatory and inhibitory factors. We investigated multiple channel bridges for spinal cord regeneration and correlated the bridge structure to cell infiltration and axonal elongation. Poly(lactide-co-glycolide) bridges were fabricated by a gas foaming/particulate leaching process. Channels within the bridge had diameters of 150 or 250 μm, and the main body of the bridge was highly porous with a controllable pore size. Upon implantation in a rat spinal cord hemisection site, cells infiltrated into the bridge pores and channels, with the pore size influencing the rate of infiltration. The pores had significant cell infiltration, including fibroblasts, macrophages, S-100β-positive cells, and endothelial cells. The channels of the bridge were completely infiltrated with cells, which had aligned axially, and consisted primarily of fibroblasts, S-100β-positive cells, and endothelial cells. Reactive astrocytes were observed primarily outside of the bridge, and staining for chondroitin sulfate proteoglycans was decreased in the region surrounding the bridge relative to studies without bridges. Neurofilament staining revealed a preferential growth of the neural fibers within the bridge channels relative to the pores. Multiple channel bridges capable of supporting cellular infiltration, creating a permissive environment, and directing the growth of neural fibers have potential for promoting and directing spinal cord regeneration. PMID:19382871

  18. Multiplexed, High Density Electrophysiology with Nanofabricated Neural Probes

    PubMed Central

    Du, Jiangang; Blanche, Timothy J.; Harrison, Reid R.; Lester, Henry A.; Masmanidis, Sotiris C.

    2011-01-01

    Extracellular electrode arrays can reveal the neuronal network correlates of behavior with single-cell, single-spike, and sub-millisecond resolution. However, implantable electrodes are inherently invasive, and efforts to scale up the number and density of recording sites must compromise on device size in order to connect the electrodes. Here, we report on silicon-based neural probes employing nanofabricated, high-density electrical leads. Furthermore, we address the challenge of reading out multichannel data with an application-specific integrated circuit (ASIC) performing signal amplification, band-pass filtering, and multiplexing functions. We demonstrate high spatial resolution extracellular measurements with a fully integrated, low noise 64-channel system weighing just 330 mg. The on-chip multiplexers make possible recordings with substantially fewer external wires than the number of input channels. By combining nanofabricated probes with ASICs we have implemented a system for performing large-scale, high-density electrophysiology in small, freely behaving animals that is both minimally invasive and highly scalable. PMID:22022568

  19. Parietal neural prosthetic control of a computer cursor in a graphical-user-interface task

    NASA Astrophysics Data System (ADS)

    Revechkis, Boris; Aflalo, Tyson NS; Kellis, Spencer; Pouratian, Nader; Andersen, Richard A.

    2014-12-01

    Objective. To date, the majority of Brain-Machine Interfaces have been used to perform simple tasks with sequences of individual targets in otherwise blank environments. In this study we developed a more practical and clinically relevant task that approximated modern computers and graphical user interfaces (GUIs). This task could be problematic given the known sensitivity of areas typically used for BMIs to visual stimuli, eye movements, decision-making, and attentional control. Consequently, we sought to assess the effect of a complex, GUI-like task on the quality of neural decoding. Approach. A male rhesus macaque monkey was implanted with two 96-channel electrode arrays in area 5d of the superior parietal lobule. The animal was trained to perform a GUI-like ‘Face in a Crowd’ task on a computer screen that required selecting one cued, icon-like, face image from a group of alternatives (the ‘Crowd’) using a neurally controlled cursor. We assessed whether the crowd affected decodes of intended cursor movements by comparing it to a ‘Crowd Off’ condition in which only the matching target appeared without alternatives. We also examined if training a neural decoder with the Crowd On rather than Off had any effect on subsequent decode quality. Main results. Despite the additional demands of working with the Crowd On, the animal was able to robustly perform the task under Brain Control. The presence of the crowd did not itself affect decode quality. Training the decoder with the Crowd On relative to Off had no negative influence on subsequent decoding performance. Additionally, the subject was able to gaze around freely without influencing cursor position. Significance. Our results demonstrate that area 5d recordings can be used for decoding in a complex, GUI-like task with free gaze. Thus, this area is a promising source of signals for neural prosthetics that utilize computing devices with GUI interfaces, e.g. personal computers, mobile devices, and tablet

  20. Parietal neural prosthetic control of a computer cursor in a graphical-user-interface task.

    PubMed

    Revechkis, Boris; Aflalo, Tyson N S; Kellis, Spencer; Pouratian, Nader; Andersen, Richard A

    2014-12-01

    To date, the majority of Brain-Machine Interfaces have been used to perform simple tasks with sequences of individual targets in otherwise blank environments. In this study we developed a more practical and clinically relevant task that approximated modern computers and graphical user interfaces (GUIs). This task could be problematic given the known sensitivity of areas typically used for BMIs to visual stimuli, eye movements, decision-making, and attentional control. Consequently, we sought to assess the effect of a complex, GUI-like task on the quality of neural decoding. A male rhesus macaque monkey was implanted with two 96-channel electrode arrays in area 5d of the superior parietal lobule. The animal was trained to perform a GUI-like 'Face in a Crowd' task on a computer screen that required selecting one cued, icon-like, face image from a group of alternatives (the 'Crowd') using a neurally controlled cursor. We assessed whether the crowd affected decodes of intended cursor movements by comparing it to a 'Crowd Off' condition in which only the matching target appeared without alternatives. We also examined if training a neural decoder with the Crowd On rather than Off had any effect on subsequent decode quality. Despite the additional demands of working with the Crowd On, the animal was able to robustly perform the task under Brain Control. The presence of the crowd did not itself affect decode quality. Training the decoder with the Crowd On relative to Off had no negative influence on subsequent decoding performance. Additionally, the subject was able to gaze around freely without influencing cursor position. Our results demonstrate that area 5d recordings can be used for decoding in a complex, GUI-like task with free gaze. Thus, this area is a promising source of signals for neural prosthetics that utilize computing devices with GUI interfaces, e.g. personal computers, mobile devices, and tablet computers.

  1. Conductive nanogel-interfaced neural microelectrode arrays with electrically controlled in-situ delivery of manganese ions enabling high-resolution MEMRI for synchronous neural tracing with deep brain stimulation.

    PubMed

    Huang, Wei-Chen; Lo, Yu-Chih; Chu, Chao-Yi; Lai, Hsin-Yi; Chen, You-Yin; Chen, San-Yuan

    2017-04-01

    Chronic brain stimulation has become a promising physical therapy with increased efficacy and efficiency in the treatment of neurodegenerative diseases. The application of deep brain electrical stimulation (DBS) combined with manganese-enhanced magnetic resonance imaging (MEMRI) provides an unbiased representation of the functional anatomy, which shows the communication between areas of the brain responding to the therapy. However, it is challenging for the current system to provide a real-time high-resolution image because the incorporated MnCl 2 solution through microinjection usually results in image blurring or toxicity due to the uncontrollable diffusion of Mn 2+ . In this study, we developed a new type of conductive nanogel-based neural interface composed of amphiphilic chitosan-modified poly(3,4 -ethylenedioxythiophene) (PMSDT) that can exhibit biomimic structural/mechanical properties and ionic/electrical conductivity comparable to that of Au. More importantly, the PMSDT enables metal-ligand bonding with Mn 2+ ions, so that the system can release Mn 2+ ions rather than MnCl 2 solution directly and precisely controlled by electrical stimulation (ES) to achieve real-time high-resolution MEMRI. With the integration of PMSDT nanogel-based coating in polyimide-based microelectrode arrays, the post-implantation DBS enables frequency-dependent MR imaging in vivo, as well as small focal imaging in response to channel site-specific stimulation on the implant. The MR imaging of the implanted brain treated with 5-min electrical stimulation showed a thalamocortical neuronal pathway after 36 h, confirming the effective activation of a downstream neuronal circuit following DBS. By eliminating the susceptibility to artifact and toxicity, this system, in combination with a MR-compatible implant and a bio-compliant neural interface, provides a harmless and synchronic functional anatomy for DBS. The study demonstrates a model of MEMRI-functionalized DBS based on functional

  2. Cochlear Implants Special Issue Article: Vocal Emotion Recognition by Normal-Hearing Listeners and Cochlear Implant Users

    PubMed Central

    Luo, Xin; Fu, Qian-Jie; Galvin, John J.

    2007-01-01

    The present study investigated the ability of normal-hearing listeners and cochlear implant users to recognize vocal emotions. Sentences were produced by 1 male and 1 female talker according to 5 target emotions: angry, anxious, happy, sad, and neutral. Overall amplitude differences between the stimuli were either preserved or normalized. In experiment 1, vocal emotion recognition was measured in normal-hearing and cochlear implant listeners; cochlear implant subjects were tested using their clinically assigned processors. When overall amplitude cues were preserved, normal-hearing listeners achieved near-perfect performance, whereas listeners with cochlear implant recognized less than half of the target emotions. Removing the overall amplitude cues significantly worsened mean normal-hearing and cochlear implant performance. In experiment 2, vocal emotion recognition was measured in listeners with cochlear implant as a function of the number of channels (from 1 to 8) and envelope filter cutoff frequency (50 vs 400 Hz) in experimental speech processors. In experiment 3, vocal emotion recognition was measured in normal-hearing listeners as a function of the number of channels (from 1 to 16) and envelope filter cutoff frequency (50 vs 500 Hz) in acoustic cochlear implant simulations. Results from experiments 2 and 3 showed that both cochlear implant and normal-hearing performance significantly improved as the number of channels or the envelope filter cutoff frequency was increased. The results suggest that spectral, temporal, and overall amplitude cues each contribute to vocal emotion recognition. The poorer cochlear implant performance is most likely attributable to the lack of salient pitch cues and the limited functional spectral resolution. PMID:18003871

  3. [Cochlear implantation in patients with Waardenburg syndrome type II].

    PubMed

    Wan, Liangcai; Guo, Menghe; Chen, Shuaijun; Liu, Shuangriu; Chen, Hao; Gong, Jian

    2010-05-01

    To describe the multi-channel cochlear implantation in patients with Waardenburg syndrome including surgeries, pre and postoperative hearing assessments as well as outcomes of speech recognition. Multi-channel cochlear implantation surgeries have been performed in 12 cases with Waardenburg syndrome type II in our department from 2000 to 2008. All the patients received multi-channel cochlear implantation through transmastoid facial recess approach. The postoperative outcomes of 12 cases were compared with 12 cases with no inner ear malformation as a control group. The electrodes were totally inserted into the cochlear successfully, there was no facial paralysis and cerebrospinal fluid leakage occurred after operation. The hearing threshold in this series were similar to that of the normal cochlear implantation. After more than half a year of speech rehabilitation, the abilities of speech discrimination and spoken language of all the patients were improved compared with that of preoperation. Multi-channel cochlear implantation could be performed in the cases with Waardenburg syndrome, preoperative hearing and images assessments should be done.

  4. Temperature-Robust Neural Function from Activity-Dependent Ion Channel Regulation.

    PubMed

    O'Leary, Timothy; Marder, Eve

    2016-11-07

    Many species of cold-blooded animals experience substantial and rapid fluctuations in body temperature. Because biological processes are differentially temperature dependent, it is difficult to understand how physiological processes in such animals can be temperature robust [1-8]. Experiments have shown that core neural circuits, such as the pyloric circuit of the crab stomatogastric ganglion (STG), exhibit robust neural activity in spite of large (20°C) temperature fluctuations [3, 5, 7, 8]. This robustness is surprising because (1) each neuron has many different kinds of ion channels with different temperature dependencies (Q 10 s) that interact in a highly nonlinear way to produce firing patterns and (2) across animals there is substantial variability in conductance densities that nonetheless produce almost identical firing properties. The high variability in conductance densities in these neurons [9, 10] appears to contradict the possibility that robustness is achieved through precise tuning of key temperature-dependent processes. In this paper, we develop a theoretical explanation for how temperature robustness can emerge from a simple regulatory control mechanism that is compatible with highly variable conductance densities [11-13]. The resulting model suggests a general mechanism for how nervous systems and excitable tissues can exploit degenerate relationships among temperature-sensitive processes to achieve robust function. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. NeuroMEMS: Neural Probe Microtechnologies

    PubMed Central

    HajjHassan, Mohamad; Chodavarapu, Vamsy; Musallam, Sam

    2008-01-01

    Neural probe technologies have already had a significant positive effect on our understanding of the brain by revealing the functioning of networks of biological neurons. Probes are implanted in different areas of the brain to record and/or stimulate specific sites in the brain. Neural probes are currently used in many clinical settings for diagnosis of brain diseases such as seizers, epilepsy, migraine, Alzheimer's, and dementia. We find these devices assisting paralyzed patients by allowing them to operate computers or robots using their neural activity. In recent years, probe technologies were assisted by rapid advancements in microfabrication and microelectronic technologies and thus are enabling highly functional and robust neural probes which are opening new and exciting avenues in neural sciences and brain machine interfaces. With a wide variety of probes that have been designed, fabricated, and tested to date, this review aims to provide an overview of the advances and recent progress in the microfabrication techniques of neural probes. In addition, we aim to highlight the challenges faced in developing and implementing ultra-long multi-site recording probes that are needed to monitor neural activity from deeper regions in the brain. Finally, we review techniques that can improve the biocompatibility of the neural probes to minimize the immune response and encourage neural growth around the electrodes for long term implantation studies. PMID:27873894

  6. Polymeric Packaging for Fully Implantable Wireless Neural Microsensors

    PubMed Central

    Aceros, Juan; Yin, Ming; Borton, David A.; Patterson, William R.; Bull, Christopher; Nurmikko, Arto V.

    2014-01-01

    We present polymeric packaging methods used for subcutaneous, fully implantable, broadband, and wireless neurosensors. A new tool for accelerated testing and characterization of biocompatible polymeric packaging materials and processes is described along with specialized test units to simulate our fully implantable neurosensor components, materials and fabrication processes. A brief description of the implantable systems is presented along with their current encapsulation methods based on polydimethylsiloxane (PDMS). Results from in-vivo testing of multiple implanted neurosensors in swine and non-human primates are presented. Finally, a novel augmenting polymer thin film material to complement the currently employed PDMS is introduced. This thin layer coating material is based on the Plasma Enhanced Chemical Vapor Deposition (PECVD) process of Hexamethyldisiloxane (HMDSO) and Oxygen (O2). PMID:23365999

  7. Effects of ion channel noise on neural circuits: an application to the respiratory pattern generator to investigate breathing variability.

    PubMed

    Yu, Haitao; Dhingra, Rishi R; Dick, Thomas E; Galán, Roberto F

    2017-01-01

    Neural activity generally displays irregular firing patterns even in circuits with apparently regular outputs, such as motor pattern generators, in which the output frequency fluctuates randomly around a mean value. This "circuit noise" is inherited from the random firing of single neurons, which emerges from stochastic ion channel gating (channel noise), spontaneous neurotransmitter release, and its diffusion and binding to synaptic receptors. Here we demonstrate how to expand conductance-based network models that are originally deterministic to include realistic, physiological noise, focusing on stochastic ion channel gating. We illustrate this procedure with a well-established conductance-based model of the respiratory pattern generator, which allows us to investigate how channel noise affects neural dynamics at the circuit level and, in particular, to understand the relationship between the respiratory pattern and its breath-to-breath variability. We show that as the channel number increases, the duration of inspiration and expiration varies, and so does the coefficient of variation of the breath-to-breath interval, which attains a minimum when the mean duration of expiration slightly exceeds that of inspiration. For small channel numbers, the variability of the expiratory phase dominates over that of the inspiratory phase, and vice versa for large channel numbers. Among the four different cell types in the respiratory pattern generator, pacemaker cells exhibit the highest sensitivity to channel noise. The model shows that suppressing input from the pons leads to longer inspiratory phases, a reduction in breathing frequency, and larger breath-to-breath variability, whereas enhanced input from the raphe nucleus increases breathing frequency without changing its pattern. A major source of noise in neuronal circuits is the "flickering" of ion currents passing through the neurons' membranes (channel noise), which cannot be suppressed experimentally. Computational

  8. Wireless microsensor network solutions for neurological implantable devices

    NASA Astrophysics Data System (ADS)

    Abraham, Jose K.; Whitchurch, Ashwin; Varadan, Vijay K.

    2005-05-01

    The design and development of wireless mocrosensor network systems for the treatment of many degenerative as well as traumatic neurological disorders is presented in this paper. Due to the advances in micro and nano sensors and wireless systems, the biomedical sensors have the potential to revolutionize many areas in healthcare systems. The integration of nanodevices with neurons that are in communication with smart microsensor systems has great potential in the treatment of many neurodegenerative brain disorders. It is well established that patients suffering from either Parkinson"s disease (PD) or Epilepsy have benefited from the advantages of implantable devices in the neural pathways of the brain to alter the undesired signals thus restoring proper function. In addition, implantable devices have successfully blocked pain signals and controlled various pelvic muscles in patients with urinary and fecal incontinence. Even though the existing technology has made a tremendous impact on controlling the deleterious effects of disease, it is still in its infancy. This paper presents solutions of many problems of today's implantable and neural-electronic interface devices by combining nanowires and microelectronics with BioMEMS and applying them at cellular level for the development of a total wireless feedback control system. The only device that will actually be implanted in this research is the electrodes. All necessary controllers will be housed in accessories that are outside the body that communicate with the implanted electrodes through tiny inductively-coupled antennas. A Parkinson disease patient can just wear a hat-system close to the implantable neural probe so that the patient is free to move around, while the sensors continually monitor, record, transmit all vital information to health care specialist. In the event of a problem, the system provides an early warning to the patient while they are still mobile thus providing them the opportunity to react and

  9. Investigation of Li/Nb-sublattices in ion implanted LiNbO3 by RBS and NRA in channelling configuration

    NASA Astrophysics Data System (ADS)

    Schmidt, E.; Ritter, K.; Gärtner, K.; Wendler, E.

    2017-10-01

    Differently oriented LiNbO3 crystals were implanted at room temperature with 1 MeV iodine ions to fluences between 2 × 1013 and 1 × 1014 cm-2, which cover the transition from a low damage level up to complete amorphisation. The aim of this work was to explore the use of nuclear reaction analysis (NRA) in combination with Rutherford backscattering spectrometry (RBS) in channelling configuration for studying the damage evolution as a function of the ion fluence in both the Li and Nb sublattice. Protons with energies between 1.4 and 1.6 MeV and a standard RBS setup were used. Scattering events detected at low energies result from Rutherford backscattering of protons on Nb and O atoms. At high energies alpha particles are registered, which result from the nuclear reaction between protons and Li atoms. Along different low-index crystallographic directions channelling effects within both the RBS and NRA part of the spectra are observed. However, the strength of channeling within the NRA part depends on the crystallographic direction investigated. These effects are explained by the nature of ion-channelling with respect to the small atomic number of Li and is supported by calculations of minimum yields (ratio of scattering yield in aligned and random direction) applying the computer code DICADA. The consequence is that damage studies with NRA can be only performed in Z-direction of LiNbO3. In this case, the Li and Nb sublattice were found to be similarly damaged after 1 MeV iodine implantation.

  10. Closed-loop optical neural stimulation based on a 32-channel low-noise recording system with online spike sorting

    NASA Astrophysics Data System (ADS)

    Nguyen, T. K. T.; Navratilova, Z.; Cabral, H.; Wang, L.; Gielen, G.; Battaglia, F. P.; Bartic, C.

    2014-08-01

    Objective. Closed-loop operation of neuro-electronic systems is desirable for both scientific and clinical (neuroprosthesis) applications. Integrating optical stimulation with recording capability further enhances the selectivity of neural stimulation. We have developed a system enabling the local delivery of optical stimuli and the simultaneous electrical measuring of the neural activities in a closed-loop approach. Approach. The signal analysis is performed online through the implementation of a template matching algorithm. The system performance is demonstrated with the recorded data and in awake rats. Main results. Specifically, the neural activities are simultaneously recorded, detected, classified online (through spike sorting) from 32 channels, and used to trigger a light emitting diode light source using generated TTL signals. Significance. A total processing time of 8 ms is achieved, suitable for optogenetic studies of brain mechanisms online.

  11. Comparison of the Outcome of Silicone Ahmed Glaucoma Valve Implantation with a Surface Area between 96 and 184 mm2 in Adult Eyes

    PubMed Central

    Koh, Kyung Min; Hwang, Young Hoon; Jung, Jong Jin; Sohn, Yong Ho

    2013-01-01

    Purpose To compare the success rates, complications, and visual outcomes between silicone Ahmed glaucoma valve (AGV) implantation with 96 mm2 (FP8) or 184 mm2 (FP7) surface areas. Methods This study is a retrospective review of the records from 132 adult patients (134 eyes) that underwent silicone AGV implant surgery. Among them, the outcomes of 24 eyes from 24 patients with refractory glaucoma who underwent FP8 AGV implantation were compared with 76 eyes from 76 patients who underwent FP7 AGV implantation. Preoperative and postoperative data, including intraocular pressure (IOP), visual acuity, number of medications, and complications were compared between the 2 groups. Results There were no significant differences in baseline characteristics between the 2 groups (p > 0.05). The postoperative visual acuity of the patients in the FP8 group was better than that of the patients in the FP7 group in some early postoperative periods (p < 0.05); however, after 10 postoperative months, visual acuity was not significantly different through the 3-year follow-up period (p > 0.05). Postoperative IOP was not significantly different between the 2 groups (p > 0.05) except for IOP on postoperative day 1 (11.42 mmHg for the FP7 group and 7.42 mmHg for the FP8 group; p = 0.031). There was no statistical difference in success rates, final IOP, number of medications, or complication rates between the 2 groups (p > 0.05). Conclusions The FP7 and FP8 AGV implants showed no difference in terms of vision preservation, IOP reduction, and number of glaucoma medications required. PMID:24082774

  12. Number of implants for mandibular implant overdentures: a systematic review

    PubMed Central

    Lee, Jeong-Yol; Kim, Ha-Young; Bryant, S. Ross

    2012-01-01

    PURPOSE The aim of this systematic review is to address treatment outcomes of Mandibular implant overdentures relative to implant survival rate, maintenance and complications, and patient satisfaction. MATERIALS AND METHODS A systematic literature search was conducted by a PubMed search strategy and hand-searching of relevant journals from included studies. Randomized Clinical Trials (RCT) and comparative clinical trial studies on mandibular implant overdentures until August, 2010 were selected. Eleven studies from 1098 studies were finally selected and data were analyzed relative to number of implants. RESULTS Six studies presented the data of the implant survival rate which ranged from 95% to 100% for 2 and 4 implant group and from 81.8% to 96.1% for 1 and 2 implant group. One study, which statistically compared implant survival rate showed no significant differences relative to the number of implants. The most common type of prosthetic maintenance and complications were replacement or reattaching of loose clips for 2 and 4 implant group, and denture repair due to the fracture around an implant for 1 and 2 implant groups. Most studies showed no significant differences in the rate of prosthetic maintenance and complication, and patient satisfaction regardless the number of implants. CONCLUSION The implant survival rate of mandibular overdentures is high regardless of the number of implants. Denture maintenance is likely not inflenced substantially by the number of implants and patient satisfaction is typically high again regardless os the number of implants. PMID:23236572

  13. Cochlear implants: system design, integration, and evaluation.

    PubMed

    Zeng, Fan-Gang; Rebscher, Stephen; Harrison, William; Sun, Xiaoan; Feng, Haihong

    2008-01-01

    As the most successful neural prosthesis, cochlear implants have provided partial hearing to more than 120000 persons worldwide; half of which being pediatric users who are able to develop nearly normal language. Biomedical engineers have played a central role in the design, integration and evaluation of the cochlear implant system, but the overall success is a result of collaborative work with physiologists, psychologists, physicians, educators, and entrepreneurs. This review presents broad yet in-depth academic and industrial perspectives on the underlying research and ongoing development of cochlear implants. The introduction accounts for major events and advances in cochlear implants, including dynamic interplays among engineers, scientists, physicians, and policy makers. The review takes a system approach to address critical issues in cochlear implant research and development. First, the cochlear implant system design and specifications are laid out. Second, the design goals, principles, and methods of the subsystem components are identified from the external speech processor and radio frequency transmission link to the internal receiver, stimulator and electrode arrays. Third, system integration and functional evaluation are presented with respect to safety, reliability, and challenges facing the present and future cochlear implant designers and users. Finally, issues beyond cochlear implants are discussed to address treatment options for the entire spectrum of hearing impairment as well as to use the cochlear implant as a model to design and evaluate other similar neural prostheses such as vestibular and retinal implants.

  14. Low-Power, 8-Channel EEG Recorder and Seizure Detector ASIC for a Subdermal Implantable System.

    PubMed

    Do Valle, Bruno G; Cash, Sydney S; Sodini, Charles G

    2016-12-01

    EEG remains the mainstay test for the diagnosis and treatment of patients with epilepsy. Unfortunately, ambulatory EEG systems are far from ideal for patients who have infrequent seizures. These systems only last up to 3 days and if a seizure is not captured during the recordings, a definite diagnosis of the patient's condition cannot be given. This work aims to address this need by proposing a subdermal implantable, eight-channel EEG recorder and seizure detector that has two modes of operation: diagnosis and seizure counting. In the diagnosis mode, EEG is continuously recorded until a number of seizures are recorded. In the seizure counting mode, the system uses a low-power algorithm to track the number of seizures a patient has, providing doctors with a reliable count to help determine medication efficacy or other clinical endpoint. An ASIC that implements the EEG recording and seizure detection algorithm was designed and fabricated in a 0.18 μm CMOS process. The ASIC includes eight EEG channels and is designed to minimize the system's power and size. The result is a power-efficient analog front end that requires 2.75 μW per channel in diagnosis mode and 0.84 μW per channel in seizure counting mode. Both modes have an input referred noise of approximately 1.1 μVrms.

  15. Opacity annotation of diffuse lung diseases using deep convolutional neural network with multi-channel information

    NASA Astrophysics Data System (ADS)

    Mabu, Shingo; Kido, Shoji; Hashimoto, Noriaki; Hirano, Yasushi; Kuremoto, Takashi

    2018-02-01

    This research proposes a multi-channel deep convolutional neural network (DCNN) for computer-aided diagnosis (CAD) that classifies normal and abnormal opacities of diffuse lung diseases in Computed Tomography (CT) images. Because CT images are gray scale, DCNN usually uses one channel for inputting image data. On the other hand, this research uses multi-channel DCNN where each channel corresponds to the original raw image or the images transformed by some preprocessing techniques. In fact, the information obtained only from raw images is limited and some conventional research suggested that preprocessing of images contributes to improving the classification accuracy. Thus, the combination of the original and preprocessed images is expected to show higher accuracy. The proposed method realizes region of interest (ROI)-based opacity annotation. We used lung CT images taken in Yamaguchi University Hospital, Japan, and they are divided into 32 × 32 ROI images. The ROIs contain six kinds of opacities: consolidation, ground-glass opacity (GGO), emphysema, honeycombing, nodular, and normal. The aim of the proposed method is to classify each ROI into one of the six opacities (classes). The DCNN structure is based on VGG network that secured the first and second places in ImageNet ILSVRC-2014. From the experimental results, the classification accuracy of the proposed method was better than the conventional method with single channel, and there was a significant difference between them.

  16. Low-Cutoff, High-Pass Digital Filtering of Neural Signals

    NASA Technical Reports Server (NTRS)

    Mojarradi,Mohammad; Johnson, Travis; Ortiz, Monico; Cunningham, Thomas; Andersen, Richard

    2004-01-01

    The figure depicts the major functional blocks of a system, now undergoing development, for conditioning neural signals acquired by electrodes implanted in a brain. The overall functions to be performed by this system can be summarized as preamplification, multiplexing, digitization, and high-pass filtering. Other systems under development for recording neural signals typically contain resistor-capacitor analog low-pass filters characterized by cutoff frequencies in the vicinity of 100 Hz. In the application for which this system is being developed, there is a requirement for a cutoff frequency of 5 Hz. Because the resistors needed to obtain such a low cutoff frequency would be impractically large, it was decided to perform low-pass filtering by use of digital rather than analog circuitry. In addition, it was decided to timemultiplex the digitized signals from the multiple input channels into a single stream of data in a single output channel. The signal in each input channel is first processed by a preamplifier having a voltage gain of approximately 50. Embedded in each preamplifier is a low-pass anti-aliasing filter having a cutoff frequency of approximately 10 kHz. The anti-aliasing filters make it possible to couple the outputs of the preamplifiers to the input ports of a multiplexer. The output of the multiplexer is a single stream of time-multiplexed samples of analog signals. This stream is processed by a main differential amplifier, the output of which is sent to an analog-to-digital converter (ADC). The output of the ADC is sent to a digital signal processor (DSP).

  17. In-Situ RBS Channelling Studies Of Ion Implanted Semiconductors And Insulators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wendler, E.

    2011-06-01

    The experimental set-up at the ion beam facility in Jena allows the performance of Rutherford backscattering spectrometry (RBS) in channeling configuration at any temperature between 15 K and room temperature without changing the environment or the temperature of the sample. Doing RBS channeling studies at 15 K increases the sensitivity to defects, because the influence of lattice vibrations is reduced. Thus, the very early processes of ion induced damage formation can be studied and the cross section of damage formation per ion in virgin material, P, can be determined. At 15 K ion-beam induced damage formation itself can be investigated,more » because the occurrence of thermal effects can be widely excluded. In AlAs, GaN, and ZnO the cross section P measured at 15 K can be used to estimate the displacement energy for the heavier component, which is in reasonable agreement with other experiments or theoretical calculations. For a given ion species (here Ar ions) the measured cross section P exhibits a quadratic dependence P{proportional_to}P{sub SRIM}{sup 2} with P{sub SRIM} being the value calculated with SRIM using established displacement energies from other sources. From these results the displacement energy of AlN can be estimated to about 40 eV. Applying the computer code DICADA to calculate the depth distribution of displaced lattice atoms from the channeling spectra, indirect information about the type of defects produced during ion implantation at 15 K can be obtained. In some materials like GaN or ZnO the results indicate the formation of extended defects most probably dislocation loops and thus suggest an athermal mobility of defect at 15 K.« less

  18. Cochlear implant magnet retrofit.

    PubMed

    Cohen, N L; Breda, S D; Hoffman, R A

    1988-06-01

    An implantable magnet is now available for patients who have received the standard Nucleus 22-channel cochlear implant and who are not able to wear the headband satisfactorily. This magnet is attached in piggy-back fashion to the previously implanted receiver/stimulator by means of a brief operation under local anesthesia. Two patients have received this magnet retrofit, and are now wearing the headset with greater comfort and satisfaction. It is felt that the availability of this magnet will increase patient compliance in regard to hours of implant usage.

  19. A hybrid microfluidic system for regulation of neural differentiation in induced pluripotent stem cells.

    PubMed

    Hesari, Zahra; Soleimani, Massoud; Atyabi, Fatemeh; Sharifdini, Meysam; Nadri, Samad; Warkiani, Majid Ebrahimi; Zare, Mehrak; Dinarvand, Rassoul

    2016-06-01

    Controlling cellular orientation, proliferation, and differentiation is valuable in designing organ replacements and directing tissue regeneration. In the present study, we developed a hybrid microfluidic system to produce a dynamic microenvironment by placing aligned PDMS microgrooves on surface of biodegradable polymers as physical guidance cues for controlling the neural differentiation of human induced pluripotent stem cells (hiPSCs). The neuronal differentiation capacity of cultured hiPSCs in the microfluidic system and other control groups was investigated using quantitative real time PCR (qPCR) and immunocytochemistry. The functionally of differentiated hiPSCs inside hybrid system's scaffolds was also evaluated on the rat hemisected spinal cord in acute phase. Implanted cell's fate was examined using tissue freeze section and the functional recovery was evaluated according to the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale. Our results confirmed the differentiation of hiPSCs to neuronal cells on the microfluidic device where the expression of neuronal-specific genes was significantly higher compared to those cultured on the other systems such as plain tissue culture dishes and scaffolds without fluidic channels. Although survival and integration of implanted hiPSCs did not lead to a significant functional recovery, we believe that combination of fluidic channels with nanofiber scaffolds provides a great microenvironment for neural tissue engineering, and can be used as a powerful tool for in situ monitoring of differentiation potential of various kinds of stem cells. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1534-1543, 2016. © 2016 Wiley Periodicals, Inc.

  20. Implantation of Neural Probes in the Brain Elicits Oxidative Stress

    PubMed Central

    Ereifej, Evon S.; Rial, Griffin M.; Hermann, John K.; Smith, Cara S.; Meade, Seth M.; Rayyan, Jacob M.; Chen, Keying; Feng, He; Capadona, Jeffrey R.

    2018-01-01

    Clinical implantation of intracortical microelectrodes has been hindered, at least in part, by the perpetual inflammatory response occurring after device implantation. The neuroinflammatory response observed after device implantation has been correlated to oxidative stress that occurs due to neurological injury and disease. However, there has yet to be a definitive link of oxidative stress to intracortical microelectrode implantation. Thus, the objective of this study is to give direct evidence of oxidative stress following intracortical microelectrode implantation. This study also aims to identify potential molecular targets to attenuate oxidative stress observed postimplantation. Here, we implanted adult rats with silicon non-functional microelectrode probes for 4 weeks and compared the oxidative stress response to no surgery controls through postmortem gene expression analysis and qualitative histological observation of oxidative stress markers. Gene expression analysis results at 4 weeks postimplantation indicated that EH domain-containing 2, prion protein gene (Prnp), and Stearoyl-Coenzyme A desaturase 1 (Scd1) were all significantly higher for animals implanted with intracortical microelectrode probes compared to no surgery control animals. To the contrary, NADPH oxidase activator 1 (Noxa1) relative gene expression was significantly lower for implanted animals compared to no surgery control animals. Histological observation of oxidative stress showed an increased expression of oxidized proteins, lipids, and nucleic acids concentrated around the implant site. Collectively, our results reveal there is a presence of oxidative stress following intracortical microelectrode implantation compared to no surgery controls. Further investigation targeting these specific oxidative stress linked genes could be beneficial to understanding potential mechanisms and downstream therapeutics that can be utilized to reduce oxidative stress-mediated damage following

  1. “Optical communication with brain cells by means of an implanted duplex micro-device with optogenetics and Ca2+ fluoroimaging”

    PubMed Central

    Kobayashi, Takuma; Haruta, Makito; Sasagawa, Kiyotaka; Matsumata, Miho; Eizumi, Kawori; Kitsumoto, Chikara; Motoyama, Mayumi; Maezawa, Yasuyo; Ohta, Yasumi; Noda, Toshihiko; Tokuda, Takashi; Ishikawa, Yasuyuki; Ohta, Jun

    2016-01-01

    To better understand the brain function based on neural activity, a minimally invasive analysis technology in a freely moving animal is necessary. Such technology would provide new knowledge in neuroscience and contribute to regenerative medical techniques and prosthetics care. An application that combines optogenetics for voluntarily stimulating nerves, imaging to visualize neural activity, and a wearable micro-instrument for implantation into the brain could meet the abovementioned demand. To this end, a micro-device that can be applied to the brain less invasively and a system for controlling the device has been newly developed in this study. Since the novel implantable device has dual LEDs and a CMOS image sensor, photostimulation and fluorescence imaging can be performed simultaneously. The device enables bidirectional communication with the brain by means of light. In the present study, the device was evaluated in an in vitro experiment using a new on-chip 3D neuroculture with an extracellular matrix gel and an in vivo experiment involving regenerative medical transplantation and gene delivery to the brain by using both photosensitive channel and fluorescent Ca2+ indicator. The device succeeded in activating cells locally by selective photostimulation, and the physiological Ca2+ dynamics of neural cells were visualized simultaneously by fluorescence imaging. PMID:26878910

  2. “Optical communication with brain cells by means of an implanted duplex micro-device with optogenetics and Ca2+ fluoroimaging”

    NASA Astrophysics Data System (ADS)

    Kobayashi, Takuma; Haruta, Makito; Sasagawa, Kiyotaka; Matsumata, Miho; Eizumi, Kawori; Kitsumoto, Chikara; Motoyama, Mayumi; Maezawa, Yasuyo; Ohta, Yasumi; Noda, Toshihiko; Tokuda, Takashi; Ishikawa, Yasuyuki; Ohta, Jun

    2016-02-01

    To better understand the brain function based on neural activity, a minimally invasive analysis technology in a freely moving animal is necessary. Such technology would provide new knowledge in neuroscience and contribute to regenerative medical techniques and prosthetics care. An application that combines optogenetics for voluntarily stimulating nerves, imaging to visualize neural activity, and a wearable micro-instrument for implantation into the brain could meet the abovementioned demand. To this end, a micro-device that can be applied to the brain less invasively and a system for controlling the device has been newly developed in this study. Since the novel implantable device has dual LEDs and a CMOS image sensor, photostimulation and fluorescence imaging can be performed simultaneously. The device enables bidirectional communication with the brain by means of light. In the present study, the device was evaluated in an in vitro experiment using a new on-chip 3D neuroculture with an extracellular matrix gel and an in vivo experiment involving regenerative medical transplantation and gene delivery to the brain by using both photosensitive channel and fluorescent Ca2+ indicator. The device succeeded in activating cells locally by selective photostimulation, and the physiological Ca2+ dynamics of neural cells were visualized simultaneously by fluorescence imaging.

  3. A highly compliant serpentine shaped polyimide interconnect for front-end strain relief in chronic neural implants.

    PubMed

    Sankar, Viswanath; Sanchez, Justin C; McCumiskey, Edward; Brown, Nagid; Taylor, Curtis R; Ehlert, Gregory J; Sodano, Henry A; Nishida, Toshikazu

    2013-01-01

    While the signal quality of recording neural electrodes is observed to degrade over time, the degradation mechanisms are complex and less easily observable. Recording microelectrodes failures are attributed to different biological factors such as tissue encapsulation, immune response, and disruption of blood-brain barrier (BBB) and non-biological factors such as strain due to micromotion, insulation delamination, corrosion, and surface roughness on the recording site (1-4). Strain due to brain micromotion is considered to be one of the important abiotic factors contributing to the failure of the neural implants. To reduce the forces exerted by the electrode on the brain, a high compliance 2D serpentine shaped electrode cable was designed, simulated, and measured using polyimide as the substrate material. Serpentine electrode cables were fabricated using MEMS microfabrication techniques, and the prototypes were subjected to load tests to experimentally measure the compliance. The compliance of the serpentine cable was numerically modeled and quantitatively measured to be up to 10 times higher than the compliance of a straight cable of same dimensions and material.

  4. A Highly Compliant Serpentine Shaped Polyimide Interconnect for Front-End Strain Relief in Chronic Neural Implants

    PubMed Central

    Sankar, Viswanath; Sanchez, Justin C.; McCumiskey, Edward; Brown, Nagid; Taylor, Curtis R.; Ehlert, Gregory J.; Sodano, Henry A.; Nishida, Toshikazu

    2013-01-01

    While the signal quality of recording neural electrodes is observed to degrade over time, the degradation mechanisms are complex and less easily observable. Recording microelectrodes failures are attributed to different biological factors such as tissue encapsulation, immune response, and disruption of blood-brain barrier (BBB) and non-biological factors such as strain due to micromotion, insulation delamination, corrosion, and surface roughness on the recording site (1–4). Strain due to brain micromotion is considered to be one of the important abiotic factors contributing to the failure of the neural implants. To reduce the forces exerted by the electrode on the brain, a high compliance 2D serpentine shaped electrode cable was designed, simulated, and measured using polyimide as the substrate material. Serpentine electrode cables were fabricated using MEMS microfabrication techniques, and the prototypes were subjected to load tests to experimentally measure the compliance. The compliance of the serpentine cable was numerically modeled and quantitatively measured to be up to 10 times higher than the compliance of a straight cable of same dimensions and material. PMID:24062716

  5. Cochlear Implants:System Design, Integration and Evaluation

    PubMed Central

    Rebscher, Stephen; Harrison, William V.; Sun, Xiaoan; Feng, Haihong

    2009-01-01

    As the most successful neural prosthesis, cochlear implants have provided partial hearing to more than 120,000 persons worldwide; half of which being pediatric users who are able to develop nearly normal language. Biomedical engineers have played a central role in the design, integration and evaluation of the cochlear implant system, but the overall success is a result of collaborative work with physiologists, psychologists, physicians, educators, and entrepreneurs. This review presents broad yet in-depth academic and industrial perspectives on the underlying research and ongoing development of cochlear implants. The introduction accounts for major events and advances in cochlear implants, including dynamic interplays among engineers, scientists, physicians, and policy makers. The review takes a system approach to address critical issues from design and specifications to integration and evaluation. First, the cochlear implant system design and specifications are laid out. Second, the design goals, principles, and methods of the subsystem components are identified from the external speech processor and radio frequency transmission link to the internal receiver, stimulator and electrode arrays. Third, system integration and functional evaluation are presented with respect to safety, reliability, and challenges facing the present and future cochlear implant designers and users. Finally, issues beyond cochlear implants are discussed to address treatment options for the entire spectrum of hearing impairment as well as to use the cochlear implant as a model to design and evaluate other similar neural prostheses such as vestibular and retinal implants. PMID:19946565

  6. Capacitive Feedthroughs for Medical Implants

    PubMed Central

    Grob, Sven; Tass, Peter A.; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging. PMID:27660602

  7. Capacitive Feedthroughs for Medical Implants.

    PubMed

    Grob, Sven; Tass, Peter A; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging.

  8. Super-pixel extraction based on multi-channel pulse coupled neural network

    NASA Astrophysics Data System (ADS)

    Xu, GuangZhu; Hu, Song; Zhang, Liu; Zhao, JingJing; Fu, YunXia; Lei, BangJun

    2018-04-01

    Super-pixel extraction techniques group pixels to form over-segmented image blocks according to the similarity among pixels. Compared with the traditional pixel-based methods, the image descripting method based on super-pixel has advantages of less calculation, being easy to perceive, and has been widely used in image processing and computer vision applications. Pulse coupled neural network (PCNN) is a biologically inspired model, which stems from the phenomenon of synchronous pulse release in the visual cortex of cats. Each PCNN neuron can correspond to a pixel of an input image, and the dynamic firing pattern of each neuron contains both the pixel feature information and its context spatial structural information. In this paper, a new color super-pixel extraction algorithm based on multi-channel pulse coupled neural network (MPCNN) was proposed. The algorithm adopted the block dividing idea of SLIC algorithm, and the image was divided into blocks with same size first. Then, for each image block, the adjacent pixels of each seed with similar color were classified as a group, named a super-pixel. At last, post-processing was adopted for those pixels or pixel blocks which had not been grouped. Experiments show that the proposed method can adjust the number of superpixel and segmentation precision by setting parameters, and has good potential for super-pixel extraction.

  9. Recent advances in neural dust: towards a neural interface platform.

    PubMed

    Neely, Ryan M; Piech, David K; Santacruz, Samantha R; Maharbiz, Michel M; Carmena, Jose M

    2018-06-01

    The neural dust platform uses ultrasonic power and communication to enable a scalable, wireless, and batteryless system for interfacing with the nervous system. Ultrasound offers several advantages over alternative wireless approaches, including a safe method for powering and communicating with sub mm-sized devices implanted deep in tissue. Early studies demonstrated that neural dust motes could wirelessly transmit high-fidelity electrophysiological data in vivo, and that theoretically, this system could be miniaturized well below the mm-scale. Future developments are focused on further minimization of the platform, better encapsulation methods as a path towards truly chronic neural interfaces, improved delivery mechanisms, stimulation capabilities, and finally refinements to enable deployment of neural dust in the central nervous system. Copyright © 2017. Published by Elsevier Ltd.

  10. A TinyOS-enabled MICA2-based wireless neural interface.

    PubMed

    Farshchi, Shahin; Nuyujukian, Paul H; Pesterev, Aleksey; Mody, Istvan; Judy, Jack W

    2006-07-01

    Existing approaches used to develop compact low-power multichannel wireless neural recording systems range from creating custom-integrated circuits to assembling commercial-off-the-shelf (COTS) PC-based components. Custom-integrated-circuit designs yield extremely compact and low-power devices at the expense of high development and upgrade costs and turn-around times, while assembling COTS-PC-technology yields high performance at the expense of large system size and increased power consumption. To achieve a balance between implementing an ultra-compact custom-fabricated neural transceiver and assembling COTS-PC-technology, an overlay of a neural interface upon the TinyOS-based MICA2 platform is described. The system amplifies, digitally encodes, and transmits neural signals real-time at a rate of 9.6 kbps, while consuming less than 66 mW of power. The neural signals are received and forwarded to a client PC over a serial connection. This data rate can be divided for recording on up to 6 channels, with a resolution of 8 bits/sample. This work demonstrates the strengths and limitations of the TinyOS-based sensor technology as a foundation for chronic remote biological monitoring applications and, thus, provides an opportunity to create a system that can leverage from the frequent networking and communications advancements being made by the global TinyOS-development community.

  11. A wireless integrated circuit for 100-channel charge-balanced neural stimulation.

    PubMed

    Thurgood, B K; Warren, D J; Ledbetter, N M; Clark, G A; Harrison, R R

    2009-12-01

    The authors present the design of an integrated circuit for wireless neural stimulation, along with benchtop and in - vivo experimental results. The chip has the ability to drive 100 individual stimulation electrodes with constant-current pulses of varying amplitude, duration, interphasic delay, and repetition rate. The stimulation is performed by using a biphasic (cathodic and anodic) current source, injecting and retracting charge from the nervous system. Wireless communication and power are delivered over a 2.765-MHz inductive link. Only three off-chip components are needed to operate the stimulator: a 10-nF capacitor to aid in power-supply regulation, a small capacitor (< 100 pF) for tuning the coil to resonance, and a coil for power and command reception. The chip was fabricated in a commercially available 0.6- mum 2P3M BiCMOS process. The chip was able to activate motor fibers to produce muscle twitches via a Utah Slanted Electrode Array implanted in cat sciatic nerve, and to activate sensory fibers to recruit evoked potentials in somatosensory cortex.

  12. Wireless Power Transfer Strategies for Implantable Bioelectronics.

    PubMed

    Agarwal, Kush; Jegadeesan, Rangarajan; Guo, Yong-Xin; Thakor, Nitish V

    2017-01-01

    Neural implants have emerged over the last decade as highly effective solutions for the treatment of dysfunctions and disorders of the nervous system. These implants establish a direct, often bidirectional, interface to the nervous system, both sensing neural signals and providing therapeutic treatments. As a result of the technological progress and successful clinical demonstrations, completely implantable solutions have become a reality and are now commercially available for the treatment of various functional disorders. Central to this development is the wireless power transfer (WPT) that has enabled implantable medical devices (IMDs) to function for extended durations in mobile subjects. In this review, we present the theory, link design, and challenges, along with their probable solutions for the traditional near-field resonant inductively coupled WPT, capacitively coupled short-ranged WPT, and more recently developed ultrasonic, mid-field, and far-field coupled WPT technologies for implantable applications. A comparison of various power transfer methods based on their power budgets and WPT range follows. Power requirements of specific implants like cochlear, retinal, cortical, and peripheral are also considered and currently available IMD solutions are discussed. Patient's safety concerns with respect to electrical, biological, physical, electromagnetic interference, and cyber security from an implanted neurotech device are also explored in this review. Finally, we discuss and anticipate future developments that will enhance the capabilities of current-day wirelessly powered implants and make them more efficient and integrable with other electronic components in IMDs.

  13. A comparison between neural response telemetry via cochleostomy or the round window approach in cochlear implantation.

    PubMed

    Hamerschmidt, Rogério; Schuch, Luiz Henrique; Rezende, Rodrigo Kopp; Wiemes, Gislaine Richter Minhoto; Oliveira, Adriana Kosma Pires de; Mocellin, Marcos

    2012-01-01

    There are two techniques for cochlear implant (CI) electrode placement: cochleostomy and the round window (RW) approach. This study aims to compare neural response telemetry (NRT) results immediately after surgery to check for possible differences on auditory nerve stimulation between these two techniques. This is a prospective cross-sectional study. Twenty-three patients were enrolled. Six patients underwent surgery by cochleostomy and 17 had it through the RW approach. Mean charge units (MCU) for high frequency sounds: patients submitted to the RW approach had a mean value of 190.4 (± 29.2) while cochleostomy patients averaged 187.8 (± 32.7); p = 0.71. MCU for mid frequency sounds: patients submitted to the RW approach had a mean value of 192.5 (± 22) while cochleostomy patients averaged 178.5 (± 18.5); p = 0.23. MCU for low frequency sounds: patients submitted to the RW approach had a mean value of 183.3 (± 25) while cochleostomy patients averaged 163.8 (± 19.3); p = 0.19. This study showed no differences in the action potential of the distal portion of the auditory nerve in patients with multichannel cochlear implants submitted to surgery by cochleostomy or through the RW approach, using the implant itself to generate stimuli and record responses. Both techniques equally stimulate the cochlear nerve. Therefore, the choice of approach can be made based on the surgeon's own preference and experience.

  14. Effects of High-Rate Pulse Trains on Electrode Discrimination in Cochlear Implant Users

    PubMed Central

    Runge-Samuelson, Christina L.

    2009-01-01

    Overcoming issues related to abnormally high neural synchrony in response to electrical stimulation is one aspect in improving hearing with a cochlear implant. Desynchronization of electrical stimuli have shown benefits in neural encoding of electrical signals and improvements in psychophysical tasks. In the present study, 10 participants with either CII or HiRes 90k Advanced Bionics devices were tested for the effects of desynchronizing constant-amplitude high-rate (5,000 Hz) pulse trains on electrode discrimination of sinusoidal stimuli (1,000 Hz). When averaged across the sinusoidal dynamic range, overall improvements in electrode discrimination with high-rate pulses were found for 8 of 10 participants. This effect was significant for the group (p = .003). Nonmonotonic patterns of electrode discrimination as a function of sinusoidal stimulation level were observed. By providing additional spectral channels, it is possible that clinical implementation of constant-amplitude high-rate pulse trains in a signal processing strategy may improve performance with the device. PMID:19447763

  15. Rodent wearable ultrasound system for wireless neural recording.

    PubMed

    Piech, David K; Kay, Joshua E; Boser, Bernhard E; Maharbiz, Michel M

    2017-07-01

    Advances in minimally-invasive, distributed biological interface nodes enable possibilities for networks of sensors and actuators to connect the brain with external devices. The recent development of the neural dust sensor mote has shown that utilizing ultrasound backscatter communication enables untethered sub-mm neural recording devices. These implanted sensor motes require a wearable external ultrasound interrogation device to enable in-vivo, freely-behaving neural interface experiments. However, minimizing the complexity and size of the implanted sensors shifts the power and processing burden to the external interrogator. In this paper, we present an ultrasound backscatter interrogator that supports real-time backscatter processing in a rodent-wearable, completely wireless device. We demonstrate a generic digital encoding scheme which is intended for transmitting neural information. The system integrates a front-end ultrasonic interface ASIC with off-the-shelf components to enable a highly compact ultrasound interrogation device intended for rodent neural interface experiments but applicable to other model systems.

  16. Implantable brain computer interface: challenges to neurotechnology translation.

    PubMed

    Konrad, Peter; Shanks, Todd

    2010-06-01

    This article reviews three concepts related to implantable brain computer interface (BCI) devices being designed for human use: neural signal extraction primarily for motor commands, signal insertion to restore sensation, and technological challenges that remain. A significant body of literature has occurred over the past four decades regarding motor cortex signal extraction for upper extremity movement or computer interface. However, little is discussed regarding postural or ambulation command signaling. Auditory prosthesis research continues to represent the majority of literature on BCI signal insertion. Significant hurdles continue in the technological translation of BCI implants. These include developing a stable neural interface, significantly increasing signal processing capabilities, and methods of data transfer throughout the human body. The past few years, however, have provided extraordinary human examples of BCI implant potential. Despite technological hurdles, proof-of-concept animal and human studies provide significant encouragement that BCI implants may well find their way into mainstream medical practice in the foreseeable future.

  17. Polyimide-based intracortical neural implant with improved structural stiffness

    NASA Astrophysics Data System (ADS)

    Lee, Kee-Keun; He, Jiping; Singh, Amarjit; Massia, Stephen; Ehteshami, Gholamreza; Kim, Bruce; Raupp, Gregory

    2004-01-01

    A novel structure for chronically implantable cortical electrodes using polyimide bio-polymer was devised, which provides both flexibility for micro-motion compliance between brain tissues and the skull and at the brain/implant interface and stiffness for better surgical handling. A 5-10 µm thick silicon backbone layer was attached to the tip of the electrode to enhance the structural stiffness. This stiff segment was then followed by a 1 mm flexible segment without a silicon backbone layer. The fabricated implants have tri-shanks with five recording sites (20 µm × 20 µm) and two vias of 40 µm × 40 µm on each shank. In vitro cytotoxicity tests of prototype implants revealed no adverse toxic effects on cells. Bench test impedance values were assessed, resulting in an average impedance value of ~2 MOmega at 1 KHz. For a 5 µm thick silicon backbone electrode, the stiffness of polyimide-based electrodes was increased ten times over that of electrodes without the silicon backbone layer. Furthermore, polyimide-based electrodes with 5 µm and 10 µm thick silicon backbone layer penetrated pia of rat brain without buckling that has been observed in implants without silicon reinforcement.

  18. Surgical factors in pediatric cochlear implantation and their early effects on electrode activation and functional outcomes.

    PubMed

    Francis, Howard W; Buchman, Craig A; Visaya, Jiovani M; Wang, Nae-Yuh; Zwolan, Teresa A; Fink, Nancy E; Niparko, John K

    2008-06-01

    To assess the impact of surgical factors on electrode status and early communication outcomes in young children in the first 2 years of cochlear implantation. Prospective multicenter cohort study. Six tertiary referral centers. Children 5 years or younger before implantation with normal nonverbal intelligence. Cochlear implant operations in 209 ears of 188 children. Percent active channels, auditory behavior as measured by the Infant Toddler Meaningful Auditory Integration Scale/Meaningful Auditory Integration Scale and Reynell receptive language scores. Stable insertion of the full electrode array was accomplished in 96.2% of ears. At least 75% of electrode channels were active in 88% of ears. Electrode deactivation had a significant negative effect on Infant Toddler Meaningful Auditory Integration Scale/Meaningful Auditory Integration Scale scores at 24 months but no effect on receptive language scores. Significantly fewer active electrodes were associated with a history of meningitis. Surgical complications requiring additional hospitalization and/or revision surgery occurred in 6.7% of patients but had no measurable effect on the development of auditory behavior within the first 2 years. Negative, although insignificant, associations were observed between the need for perioperative revision of the device and 1) the percent of active electrodes and 2) the receptive language level at 2-year follow-up. Activation of the entire electrode array is associated with better early auditory outcomes. Decrements in the number of active electrodes and lower gains of receptive language after manipulation of the newly implanted device were not statistically significant but may be clinically relevant, underscoring the importance of surgical technique and the effective placement of the electrode array.

  19. Flexible deep brain neural probes based on a parylene tube structure

    NASA Astrophysics Data System (ADS)

    Zhao, Zhiguo; Kim, Eric; Luo, Hao; Zhang, Jinsheng; Xu, Yong

    2018-01-01

    Most microfabricated neural probes have limited shank length, which prevents them from reaching many deep brain structures. This paper reports deep brain neural probes with ultra-long penetrating shanks based on a simple but novel parylene tube structure. The mechanical strength of the parylene tube shank is temporarily enhanced during implantation by inserting a metal wire. The metal wire can be removed after implantation, making the implanted probe very flexible and thus minimizing the stress caused by micromotions of brain tissues. Optogenetic stimulation and chemical delivery capabilities can be potentially integrated by taking advantage of the tube structure. Single-shank prototypes with a shank length of 18.2 mm have been developed. The microfabrication process comprises of deep reactive ion etching (DRIE) of silicon, parylene conformal coating/refilling, and XeF2 isotropic silicon etching. In addition to bench-top insertion characterization, the functionality of developed probes has been preliminarily demonstrated by implanting into the amygdala of a rat and recording neural signals.

  20. Recent Advances in Neural Electrode-Tissue Interfaces.

    PubMed

    Woeppel, Kevin; Yang, Qianru; Cui, Xinyan Tracy

    2017-12-01

    Neurotechnology is facing an exponential growth in the recent decades. Neural electrode-tissue interface research has been well recognized as an instrumental component of neurotechnology development. While satisfactory long-term performance was demonstrated in some applications, such as cochlear implants and deep brain stimulators, more advanced neural electrode devices requiring higher resolution for single unit recording or microstimulation still face significant challenges in reliability and longevity. In this article, we review the most recent findings that contribute to our current understanding of the sources of poor reliability and longevity in neural recording or stimulation, including the material failure, biological tissue response and the interplay between the two. The newly developed characterization tools are introduced from electrophysiology models, molecular and biochemical analysis, material characterization to live imaging. The effective strategies that have been applied to improve the interface are also highlighted. Finally, we discuss the challenges and opportunities in improving the interface and achieving seamless integration between the implanted electrodes and neural tissue both anatomically and functionally.

  1. Neural Interfaces for Intracortical Recording: Requirements, Fabrication Methods, and Characteristics.

    PubMed

    Szostak, Katarzyna M; Grand, Laszlo; Constandinou, Timothy G

    2017-01-01

    Implantable neural interfaces for central nervous system research have been designed with wire, polymer, or micromachining technologies over the past 70 years. Research on biocompatible materials, ideal probe shapes, and insertion methods has resulted in building more and more capable neural interfaces. Although the trend is promising, the long-term reliability of such devices has not yet met the required criteria for chronic human application. The performance of neural interfaces in chronic settings often degrades due to foreign body response to the implant that is initiated by the surgical procedure, and related to the probe structure, and material properties used in fabricating the neural interface. In this review, we identify the key requirements for neural interfaces for intracortical recording, describe the three different types of probes-microwire, micromachined, and polymer-based probes; their materials, fabrication methods, and discuss their characteristics and related challenges.

  2. Conducting polymer coated neural recording electrodes.

    PubMed

    Harris, Alexander R; Morgan, Simeon J; Chen, Jun; Kapsa, Robert M I; Wallace, Gordon G; Paolini, Antonio G

    2013-02-01

    Neural recording electrodes suffer from poor signal to noise ratio, charge density, biostability and biocompatibility. This paper investigates the ability of conducting polymer coated electrodes to record acute neural response in a systematic manner, allowing in depth comparison of electrochemical and electrophysiological response. Polypyrrole (Ppy) and poly-3,4-ethylenedioxythiophene (PEDOT) doped with sulphate (SO4) or para-toluene sulfonate (pTS) were used to coat iridium neural recording electrodes. Detailed electrochemical and electrophysiological investigations were undertaken to compare the effect of these materials on acute in vivo recording. A range of charge density and impedance responses were seen with each respectively doped conducting polymer. All coatings produced greater charge density than uncoated electrodes, while PEDOT-pTS, PEDOT-SO4 and Ppy-SO4 possessed lower impedance values at 1 kHz than uncoated electrodes. Charge density increased with PEDOT-pTS thickness and impedance at 1 kHz was reduced with deposition times up to 45 s. Stable electrochemical response after acute implantation inferred biostability of PEDOT-pTS coated electrodes while other electrode materials had variable impedance and/or charge density after implantation indicative of a protein fouling layer forming on the electrode surface. Recording of neural response to white noise bursts after implantation of conducting polymer-coated electrodes into a rat model inferior colliculus showed a general decrease in background noise and increase in signal to noise ratio and spike count with reduced impedance at 1 kHz, regardless of the specific electrode coating, compared to uncoated electrodes. A 45 s PEDOT-pTS deposition time yielded the highest signal to noise ratio and spike count. A method for comparing recording electrode materials has been demonstrated with doped conducting polymers. PEDOT-pTS showed remarkable low fouling during acute implantation, inferring good biostability

  3. Low permanent pacemaker rates following Lotus device implantation for transcatheter aortic valve replacement due to modified implantation protocol.

    PubMed

    Krackhardt, Florian; Kherad, Behrouz; Krisper, Maximilian; Pieske, Burkert; Laule, Michael; Tschöpe, Carsten

    2017-01-01

    Conduction disturbances requiring permanent pacemaker implantation following transcatheter aortic valve replacement (TAVR) are a common problem. Pacemaker implantation rates after TAVR appear to be higher compared to conventional aortic valve replacement. The aim of this study was to analyze whether a high annulus implantation conveys the benefit of a decreased rate of permanent pacemaker implantation while being safe and successful according to Valve Academic Research Consortium 2 (VARC2)-criteria. A total of 23 patients with symptomatic severe aortic valve stenosis, an aortic annulus of 19-27 mm and at high risk for surgery were treated with the Lotus valve. In all patients the valve was implanted in a high annulus position via femoral access. The primary device performance endpoint was VARC2-defined device success after 30 days and the primary safety endpoint was the need for permanent pacemaker implantation. The mean age was 73.23 ± 7.65 years, 46% were female, 38% were New York Heart Association class III/IV at baseline. Thirty-day follow-up data were available for all patients. The VARC2-defined device success rate after 30 days was 22/23 (96%). 2/21 (10%) patients required a newly implanted pacemaker due to 3rd degree atrioventricular block. 25% of the patients developed a new left bundle branch block after valvuloplasty or device implantation. 21 of the 23 patients (96%) had no other signs of conduction disturbances after 30 days. The approach of the modified implantation technique of Lotus TAVR device was safe and effective. The incidence of need for a permanent pacemaker following TAVR could be significantly reduced due to adopted implantation protocol.

  4. Biomechanical behavior of 2-implant-and single-implant-retained mandibular overdentures with conventional or mini implants.

    PubMed

    Pisani, Marina Xavier; Presotto, Anna Gabriella Camacho; Mesquita, Marcelo Ferraz; Barão, Valentim Adelino Ricardo; Kemmoku, Daniel Takanori; Del Bel Cury, Altair Antoninha

    2018-04-24

    The use of single or mini dental implants to retain mandibular overdentures is still questionable. The purpose of this finite element analysis (FEA) study was to investigate the biomechanical behavior of 2- and single-implant-retained mandibular overdentures with conventional or mini implants. Four 3-dimensional (3D) finite element models were constructed with the following designs of mandibular overdentures: 2 (group 2-C) and single (group 1-C) conventional external hexagon implants with ball or O-ring attachment and 2 (group 2-M) and single (group 1-M) 1-piece mini implants. A 150-N axial load was applied bilaterally and simultaneously on the first molar. Overdenture displacement, von Mises equivalent stress (implants and/or prosthetic components), and maximum principal stresses (peri-implant bone) were recorded numerically and then color-coded and compared among the groups. The overdenture displacement (in mm) was higher for the 1-M (0.16) and 2-M (0.17) groups when compared with 1-C (0.09) and 2-C (0.08). Irrespective of the type of implant, the single-implant groups presented higher values of stress (in MPa) on the implants than did the 2-implant groups (1-C=52.53; 1-M=2.95; 2-C=34.66; 2-M=2.37), ball attachment (1-C=201.33; 2-C=159.06), housing or O-ring (1-C=125.01; 1-M=1.96; 2-C=88.84; 2-M=1.27), and peri-implant cortical bone (1-C=19.37; 1-M=1.47; 2-C=15.70; 2-M=1.06). The mini implant overdentures presented lower stress values on the implants, housing or O-ring, and peri-implant bone than did the conventional implant overdentures, regardless of the number of implants. The 2-implant-retained overdentures exhibited lower stresses than the single- implant-retained overdentures, irrespective of the type of implant. The mini implants demonstrated higher overdenture displacement and lower stresses than did conventional implant overdentures for single- and 2-implant-retained overdentures. Copyright © 2018 Editorial Council for the Journal of Prosthetic

  5. A regenerative microchannel neural interface for recording from and stimulating peripheral axons in vivo

    NASA Astrophysics Data System (ADS)

    FitzGerald, James J.; Lago, Natalia; Benmerah, Samia; Serra, Jordi; Watling, Christopher P.; Cameron, Ruth E.; Tarte, Edward; Lacour, Stéphanie P.; McMahon, Stephen B.; Fawcett, James W.

    2012-02-01

    Neural interfaces are implanted devices that couple the nervous system to electronic circuitry. They are intended for long term use to control assistive technologies such as muscle stimulators or prosthetics that compensate for loss of function due to injury. Here we present a novel design of interface for peripheral nerves. Recording from axons is complicated by the small size of extracellular potentials and the concentration of current flow at nodes of Ranvier. Confining axons to microchannels of ˜100 µm diameter produces amplified potentials that are independent of node position. After implantation of microchannel arrays into rat sciatic nerve, axons regenerated through the channels forming ‘mini-fascicles’, each typically containing ˜100 myelinated fibres and one or more blood vessels. Regenerated motor axons reconnected to distal muscles, as demonstrated by the recovery of an electromyogram and partial prevention of muscle atrophy. Efferent motor potentials and afferent signals evoked by muscle stretch or cutaneous stimulation were easily recorded from the mini-fascicles and were in the range of 35-170 µV. Individual motor units in distal musculature were activated from channels using stimulus currents in the microampere range. Microchannel interfaces are a potential solution for applications such as prosthetic limb control or enhancing recovery after nerve injury.

  6. Recurrent neural network approach to quantum signal: coherent state restoration for continuous-variable quantum key distribution

    NASA Astrophysics Data System (ADS)

    Lu, Weizhao; Huang, Chunhui; Hou, Kun; Shi, Liting; Zhao, Huihui; Li, Zhengmei; Qiu, Jianfeng

    2018-05-01

    In continuous-variable quantum key distribution (CV-QKD), weak signal carrying information transmits from Alice to Bob; during this process it is easily influenced by unknown noise which reduces signal-to-noise ratio, and strongly impacts reliability and stability of the communication. Recurrent quantum neural network (RQNN) is an artificial neural network model which can perform stochastic filtering without any prior knowledge of the signal and noise. In this paper, a modified RQNN algorithm with expectation maximization algorithm is proposed to process the signal in CV-QKD, which follows the basic rule of quantum mechanics. After RQNN, noise power decreases about 15 dBm, coherent signal recognition rate of RQNN is 96%, quantum bit error rate (QBER) drops to 4%, which is 6.9% lower than original QBER, and channel capacity is notably enlarged.

  7. Wireless, High-Bandwidth Recordings from Non-Human Primate Motor Cortex using a Scalable 16-Ch Implantable Microsystem

    PubMed Central

    Borton, David A.; Song, Yoon-Kyu; Patterson, William R.; Bull, Christopher W.; Park, Sunmee; Laiwalla, Farah; Donoghue, John P.; Nurmikko, Arto V.

    2013-01-01

    A multitude of neuroengineering challenges exist today in creating practical, chronic multichannel neural recording systems for primate research and human clinical application. Specifically, a) the persistent wired connections limit patient mobility from the recording system, b) the transfer of high bandwidth signals to external (even distant) electronics normally forces premature data reduction, and c) the chronic susceptibility to infection due to the percutaneous nature of the implants all severely hinder the success of neural prosthetic systems. Here we detail one approach to overcome these limitations: an entirely implantable, wirelessly communicating, integrated neural recording microsystem, dubbed the Brain Implantable Chip (BIC). PMID:19964128

  8. Neural Interfaces for Intracortical Recording: Requirements, Fabrication Methods, and Characteristics

    PubMed Central

    Szostak, Katarzyna M.; Grand, Laszlo; Constandinou, Timothy G.

    2017-01-01

    Implantable neural interfaces for central nervous system research have been designed with wire, polymer, or micromachining technologies over the past 70 years. Research on biocompatible materials, ideal probe shapes, and insertion methods has resulted in building more and more capable neural interfaces. Although the trend is promising, the long-term reliability of such devices has not yet met the required criteria for chronic human application. The performance of neural interfaces in chronic settings often degrades due to foreign body response to the implant that is initiated by the surgical procedure, and related to the probe structure, and material properties used in fabricating the neural interface. In this review, we identify the key requirements for neural interfaces for intracortical recording, describe the three different types of probes—microwire, micromachined, and polymer-based probes; their materials, fabrication methods, and discuss their characteristics and related challenges. PMID:29270103

  9. Development of high impedance measurement system for water leakage detection in implantable neuroprosthetic devices.

    PubMed

    Yousif, Aziz; Kelly, Shawn K

    2016-08-01

    There has been a push for a greater number of channels in implantable neuroprosthetic devices; but, that number has largely been limited by current hermetic packaging technology. Microfabricated packaging is becoming reality, but a standard testing system is needed to prepare these devices for clinical trials. Impedance measurements of electrodes built into the packaging layers may give an early warning of device failure and predict device lifetime. Because the impedance magnitudes of such devices can be on the order of gigaohms, a versatile system was designed to accommodate ultra-high impedances and allow future integrated circuit implementation in current neural prosthetic technologies. Here we present the circuitry, control software, and preliminary testing results of our designed system.

  10. Mechanical failure modes of chronically implanted planar silicon-based neural probes for laminar recording

    PubMed Central

    Kozai, Takashi D. Y.; Catt, Kasey; Li, Xia; Gugel, Zhannetta V.; Olafsson, Valur T.; Vazquez, Alberto L.; Cui, X. Tracy

    2014-01-01

    Penetrating intracortical electrode arrays that record brain activity longitudinally are powerful tools for basic neuroscience research and emerging clinical applications. However, regardless of the technology used, signals recorded by these electrodes degrade over time. The failure mechanisms of these electrodes are understood to be a complex combination of the biological reactive tissue response and material failure of the device over time. While mechanical mismatch between the brain tissue and implanted neural electrodes have been studied as a source of chronic inflammation and performance degradation, the electrode failure caused by mechanical mismatch between different material properties and different structural components within a device have remained poorly characterized. Using Finite Element Model (FEM) we simulate the mechanical strain on a planar silicon electrode. The results presented here demonstrate that mechanical mismatch between iridium and silicon leads to concentrated strain along the border of the two materials. This strain is further focused on small protrusions such as the electrical traces in planar silicon electrodes. These findings are confirmed with chronic in vivo data (133–189 days) in mice by correlating a combination of single-unit electrophysiology, evoked multi-unit recordings, electrochemical impedance spectroscopy, and scanning electron microscopy from traces and electrode sites with our modeling data. Several modes of mechanical failure of chronically implanted planar silicon electrodes are found that result in degradation and/or loss of recording. These findings highlight the importance of strains and material properties of various subcomponents within an electrode array. PMID:25453935

  11. EDITORIAL: Special issue containing contributions from the 39th Neural Interfaces Conference Special issue containing contributions from the 39th Neural Interfaces Conference

    NASA Astrophysics Data System (ADS)

    Weiland, James D.

    2011-07-01

    Implantable neural interfaces provide substantial benefits to individuals with neurological disorders. That was the unequivocal message delivered by speaker after speaker from the podium of the 39th Neural Interfaces Conference (NIC2010) held in Long Beach, California, in June 2010. Giving benefit to patients is the most important measure for any biomedical technology, and myriad presentations at NIC2010 made clear that implantable neurostimulation technology has achieved this goal. Cochlear implants allow deaf people to communicate through speech. Deep brain stimulators give back mobility and dexterity necessary for so many daily tasks that are often taken for granted. Chronic pain can be alleviated through spinal cord stimulation. Motor prosthesis systems have been demonstrated in humans, through both reanimation of paralyzed limbs and neural control of robotic arms. Earlier this year, a retinal prosthesis was approved for sale in Europe, providing some hope for the blind. In sum, current clinical implants have been tremendously beneficial for today's patients and experimental systems that will be translated to the clinic promise to expand the number of people helped through bioelectronic therapies. Yet there are significant opportunities for improvement. For sensory prostheses, patients report an artificial sensation, clearly different from the natural sensation they remember. Neuromodulation systems, such as deep brain stimulation and pain stimulators, often have side effects that are tolerated as long as the side effects are less impactful than the disease. The papers published in the special issue from NIC2010 reflect the maturing and expanding field of neural interfaces. Our field has moved past proof-of-principle demonstrations and is now focusing on proving the longevity required for clinical implementation of new devices, extending existing approaches to new diseases and improving current devices for better outcomes. Closed-loop neuromodulation is a

  12. Implantable optoelectronic probes for in vivo optogenetics.

    PubMed

    Iseri, Ege; Kuzum, Duygu

    2017-06-01

    More than a decade has passed since optics and genetics came together and lead to the emerging technologies of optogenetics. The advent of light-sensitive opsins made it possible to optically trigger the neurons into activation or inhibition by using visible light. The importance of spatiotemporally isolating a segment of a neural network and controlling nervous signaling in a precise manner has driven neuroscience researchers and engineers to invest great efforts in designing high precision in vivo implantable devices. These efforts have focused on delivery of sufficient power to deep brain regions, while monitoring neural activity with high resolution and fidelity. In this review, we report the progress made in the field of hybrid optoelectronic neural interfaces that combine optical stimulation with electrophysiological recordings. Different approaches that incorporate optical or electrical components on implantable devices are discussed in detail. Advantages of various different designs as well as practical and fundamental limitations are summarized to illuminate the future of neurotechnology development.

  13. Implantable optoelectronic probes for in vivo optogenetics

    NASA Astrophysics Data System (ADS)

    Iseri, Ege; Kuzum, Duygu

    2017-06-01

    More than a decade has passed since optics and genetics came together and lead to the emerging technologies of optogenetics. The advent of light-sensitive opsins made it possible to optically trigger the neurons into activation or inhibition by using visible light. The importance of spatiotemporally isolating a segment of a neural network and controlling nervous signaling in a precise manner has driven neuroscience researchers and engineers to invest great efforts in designing high precision in vivo implantable devices. These efforts have focused on delivery of sufficient power to deep brain regions, while monitoring neural activity with high resolution and fidelity. In this review, we report the progress made in the field of hybrid optoelectronic neural interfaces that combine optical stimulation with electrophysiological recordings. Different approaches that incorporate optical or electrical components on implantable devices are discussed in detail. Advantages of various different designs as well as practical and fundamental limitations are summarized to illuminate the future of neurotechnology development.

  14. Scanning electron microscopy of chronically implanted intracortical microelectrode arrays in non-human primates

    NASA Astrophysics Data System (ADS)

    Barrese, James C.; Aceros, Juan; Donoghue, John P.

    2016-04-01

    Objective. Signal attenuation is a major problem facing intracortical sensors for chronic neuroprosthetic applications. Many studies suggest that failure is due to gliosis around the electrode tips, however, mechanical and material causes of failure are often overlooked. The purpose of this study was to investigate the factors contributing to progressive signal decline by using scanning electron microscopy (SEM) to visualize structural changes in chronically implanted arrays and histology to examine the tissue response at corresponding implant sites. Approach. We examined eight chronically implanted intracortical microelectrode arrays (MEAs) explanted from non-human primates at times ranging from 37 to 1051 days post-implant. We used SEM, in vivo neural recordings, and histology (GFAP, Iba-1, NeuN). Three MEAs that were never implanted were also imaged as controls. Main results. SEM revealed progressive corrosion of the platinum electrode tips and changes to the underlying silicon. The parylene insulation was prone to cracking and delamination, and in some instances the silicone elastomer also delaminated from the edges of the MEA. Substantial tissue encapsulation was observed and was often seen growing into defects in the platinum and parylene. These material defects became more common as the time in vivo increased. Histology at 37 and 1051 days post-implant showed gliosis, disruption of normal cortical architecture with minimal neuronal loss, and high Iba-1 reactivity, especially within the arachnoid and dura. Electrode tracts were either absent or barely visible in the cortex at 1051 days, but were seen in the fibrotic encapsulation material suggesting that the MEAs were lifted out of the brain. Neural recordings showed a progressive drop in impedance, signal amplitude, and viable channels over time. Significance. These results provide evidence that signal loss in MEAs is truly multifactorial. Gliosis occurs in the first few months after implantation but does

  15. Scanning electron microscopy of chronically implanted intracortical microelectrode arrays in non-human primates

    PubMed Central

    Barrese, James C; Aceros, Juan; Donoghue, John P

    2016-01-01

    Objective Signal attenuation is a major problem facing intracortical sensors for chronic neuroprosthetic applications. Many studies suggest that failure is due to gliosis around the electrode tips, however, mechanical and material causes of failure are often overlooked. The purpose of this study was to investigate the factors contributing to progressive signal decline by using scanning electron microscopy (SEM) to visualize structural changes in chronically implanted arrays and histology to examine the tissue response at corresponding implant sites. Approach We examined eight chronically implanted intracortical microelectrode arrays (MEAs) explanted from non-human primates at times ranging from 37 to 1051 days post-implant. We used SEM, in vivo neural recordings, and histology (GFAP, Iba-1, NeuN). Three MEAs that were never implanted were also imaged as controls. Main results SEM revealed progressive corrosion of the platinum electrode tips and changes to the underlying silicon. The parylene insulation was prone to cracking and delamination, and in some instances the silicone elastomer also delaminated from the edges of the MEA. Substantial tissue encapsulation was observed and was often seen growing into defects in the platinum and parylene. These material defects became more common as the time in vivo increased. Histology at 37 and 1051 days post-implant showed gliosis, disruption of normal cortical architecture with minimal neuronal loss, and high Iba-1 reactivity, especially within the arachnoid and dura. Electrode tracts were either absent or barely visible in the cortex at 1051 days, but were seen in the fibrotic encapsulation material suggesting that the MEAs were lifted out of the brain. Neural recordings showed a progressive drop in impedance, signal amplitude, and viable channels over time. Significance These results provide evidence that signal loss in MEAs is truly multifactorial. Gliosis occurs in the first few months after implantation but does not

  16. Scanning electron microscopy of chronically implanted intracortical microelectrode arrays in non-human primates.

    PubMed

    Barrese, James C; Aceros, Juan; Donoghue, John P

    2016-04-01

    Signal attenuation is a major problem facing intracortical sensors for chronic neuroprosthetic applications. Many studies suggest that failure is due to gliosis around the electrode tips, however, mechanical and material causes of failure are often overlooked. The purpose of this study was to investigate the factors contributing to progressive signal decline by using scanning electron microscopy (SEM) to visualize structural changes in chronically implanted arrays and histology to examine the tissue response at corresponding implant sites. We examined eight chronically implanted intracortical microelectrode arrays (MEAs) explanted from non-human primates at times ranging from 37 to 1051 days post-implant. We used SEM, in vivo neural recordings, and histology (GFAP, Iba-1, NeuN). Three MEAs that were never implanted were also imaged as controls. SEM revealed progressive corrosion of the platinum electrode tips and changes to the underlying silicon. The parylene insulation was prone to cracking and delamination, and in some instances the silicone elastomer also delaminated from the edges of the MEA. Substantial tissue encapsulation was observed and was often seen growing into defects in the platinum and parylene. These material defects became more common as the time in vivo increased. Histology at 37 and 1051 days post-implant showed gliosis, disruption of normal cortical architecture with minimal neuronal loss, and high Iba-1 reactivity, especially within the arachnoid and dura. Electrode tracts were either absent or barely visible in the cortex at 1051 days, but were seen in the fibrotic encapsulation material suggesting that the MEAs were lifted out of the brain. Neural recordings showed a progressive drop in impedance, signal amplitude, and viable channels over time. These results provide evidence that signal loss in MEAs is truly multifactorial. Gliosis occurs in the first few months after implantation but does not prevent useful recordings for several years

  17. Dextran as a fast resorbable and mechanically stiff coating for flexible neural probes

    NASA Astrophysics Data System (ADS)

    Kil, D.; Brancato, L.; Puers, R.

    2017-11-01

    In this paper we report on the use of dextran as a temporary, fast dissolving stiff coating for flexible neural probes. Although polymer-based neural implants offer several advantages, compared to their rigid silicon counterparts, they pose significant challenges during implantation. Due to their extreme flexibility, they have the tendency to buckle under the axial load applied during insertion. The structural stiffness of the implants can be temporarily increased by applying a bioresorbable dextran coating which eases the penetration of neural tissue. For this application three types of dextran with different molecular weights are analysed. The dissolution rate of the coatings is reported as well as the increased bending stiffness resulting from the dextran coating of Parylene C neural probes. Based on these findings the dissolution rate can be linked to parameters such as molecular weight, coating thickness and the surface area exposed to the dissolution medium. The mechanical characterization yields information on how the structural stiffness of neural probes can be tuned by varying the dextran’s molecular weight and coating thickness.

  18. A 1-channel 3-band wide dynamic range compression chip for vibration transducer of implantable hearing aids.

    PubMed

    Kim, Dongwook; Seong, Kiwoong; Kim, Myoungnam; Cho, Jinho; Lee, Jyunghyun

    2014-01-01

    In this paper, a digital audio processing chip which uses a wide dynamic range compression (WDRC) algorithm is designed and implemented for implantable hearing aids system. The designed chip operates at a single voltage of 3.3V and drives a 16 bit parallel input and output at 32 kHz sample. The designed chip has 1-channel 3-band WDRC composed of a FIR filter bank, a level detector, and a compression part. To verify the performance of the designed chip, we measured the frequency separations of bands and compression gain control to reflect the hearing threshold level.

  19. Recent refinements to cranial implants for rhesus macaques (Macaca mulatta)

    PubMed Central

    Johnston, Jessica M.; Cohen, Yale E.; Shirley, Harry; Tsunada, Joji; Bennur, Sharath; Christison-Lagay, Kate; Veeder, Christin L.

    2017-01-01

    The advent of cranial implants revolutionized primate neurophysiological research because they allow researchers to stably record neural activity from monkeys during active behavior. Cranial implants have improved over the years since their introduction, but chronic implants still increase the risk for medical complications including bacterial contamination and resultant infection, chronic inflammation, bone and tissue loss and complications related to the use of dental acrylic. These complications can lead to implant failure and early termination of study protocols. In an effort to reduce complications, we describe several refinements that have helped us improve cranial implants and the wellbeing of implanted primates. PMID:27096188

  20. Prediction and control of neural responses to pulsatile electrical stimulation

    NASA Astrophysics Data System (ADS)

    Campbell, Luke J.; Sly, David James; O'Leary, Stephen John

    2012-04-01

    This paper aims to predict and control the probability of firing of a neuron in response to pulsatile electrical stimulation of the type delivered by neural prostheses such as the cochlear implant, bionic eye or in deep brain stimulation. Using the cochlear implant as a model, we developed an efficient computational model that predicts the responses of auditory nerve fibers to electrical stimulation and evaluated the model's accuracy by comparing the model output with pooled responses from a group of guinea pig auditory nerve fibers. It was found that the model accurately predicted the changes in neural firing probability over time to constant and variable amplitude electrical pulse trains, including speech-derived signals, delivered at rates up to 889 pulses s-1. A simplified version of the model that did not incorporate adaptation was used to adaptively predict, within its limitations, the pulsatile electrical stimulus required to cause a desired response from neurons up to 250 pulses s-1. Future stimulation strategies for cochlear implants and other neural prostheses may be enhanced using similar models that account for the way that neural responses are altered by previous stimulation.

  1. Boron-Doped Nanocrystalline Diamond Electrodes for Neural Interfaces: In vivo Biocompatibility Evaluation

    PubMed Central

    Alcaide, María; Taylor, Andrew; Fjorback, Morten; Zachar, Vladimir; Pennisi, Cristian P.

    2016-01-01

    Boron-doped nanocrystalline diamond (BDD) electrodes have recently attracted attention as materials for neural electrodes due to their superior physical and electrochemical properties, however their biocompatibility remains largely unexplored. In this work, we aim to investigate the in vivo biocompatibility of BDD electrodes in relation to conventional titanium nitride (TiN) electrodes using a rat subcutaneous implantation model. High quality BDD films were synthesized on electrodes intended for use as an implantable neurostimulation device. After implantation for 2 and 4 weeks, tissue sections adjacent to the electrodes were obtained for histological analysis. Both types of implants were contained in a thin fibrous encapsulation layer, the thickness of which decreased with time. Although the level of neovascularization around the implants was similar, BDD electrodes elicited significantly thinner fibrous capsules and a milder inflammatory reaction at both time points. These results suggest that BDD films may constitute an appropriate material to support stable performance of implantable neural electrodes over time. PMID:27013949

  2. Conducting polymer coated neural recording electrodes

    NASA Astrophysics Data System (ADS)

    Harris, Alexander R.; Morgan, Simeon J.; Chen, Jun; Kapsa, Robert M. I.; Wallace, Gordon G.; Paolini, Antonio G.

    2013-02-01

    Objective. Neural recording electrodes suffer from poor signal to noise ratio, charge density, biostability and biocompatibility. This paper investigates the ability of conducting polymer coated electrodes to record acute neural response in a systematic manner, allowing in depth comparison of electrochemical and electrophysiological response. Approach. Polypyrrole (Ppy) and poly-3,4-ethylenedioxythiophene (PEDOT) doped with sulphate (SO4) or para-toluene sulfonate (pTS) were used to coat iridium neural recording electrodes. Detailed electrochemical and electrophysiological investigations were undertaken to compare the effect of these materials on acute in vivo recording. Main results. A range of charge density and impedance responses were seen with each respectively doped conducting polymer. All coatings produced greater charge density than uncoated electrodes, while PEDOT-pTS, PEDOT-SO4 and Ppy-SO4 possessed lower impedance values at 1 kHz than uncoated electrodes. Charge density increased with PEDOT-pTS thickness and impedance at 1 kHz was reduced with deposition times up to 45 s. Stable electrochemical response after acute implantation inferred biostability of PEDOT-pTS coated electrodes while other electrode materials had variable impedance and/or charge density after implantation indicative of a protein fouling layer forming on the electrode surface. Recording of neural response to white noise bursts after implantation of conducting polymer-coated electrodes into a rat model inferior colliculus showed a general decrease in background noise and increase in signal to noise ratio and spike count with reduced impedance at 1 kHz, regardless of the specific electrode coating, compared to uncoated electrodes. A 45 s PEDOT-pTS deposition time yielded the highest signal to noise ratio and spike count. Significance. A method for comparing recording electrode materials has been demonstrated with doped conducting polymers. PEDOT-pTS showed remarkable low fouling during

  3. Comparison of neural network applications for channel assignment in cellular TDMA networks and dynamically sectored PCS networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    1997-04-01

    The use of artificial neural networks (NNs) to address the channel assignment problem (CAP) for cellular time-division multiple access and code-division multiple access networks has previously been investigated by this author and many others. The investigations to date have been based on a hexagonal cell structure established by omnidirectional antennas at the base stations. No account was taken of the use of spatial isolation enabled by directional antennas to reduce interference between mobiles. Any reduction in interference translates into increased capacity and consequently alters the performance of the NNs. Previous studies have sought to improve the performance of Hopfield- Tank network algorithms and self-organizing feature map algorithms applied primarily to static channel assignment (SCA) for cellular networks that handle uniformly distributed, stationary traffic in each cell for a single type of service. The resulting algorithms minimize energy functions representing interference constraint and ad hoc conditions that promote convergence to optimal solutions. While the structures of the derived neural network algorithms (NNAs) offer the potential advantages of inherent parallelism and adaptability to changing system conditions, this potential has yet to be fulfilled the CAP for emerging mobile networks. The next-generation communication infrastructures must accommodate dynamic operating conditions. Macrocell topologies are being refined to microcells and picocells that can be dynamically sectored by adaptively controlled, directional antennas and programmable transceivers. These networks must support the time-varying demands for personal communication services (PCS) that simultaneously carry voice, data and video and, thus, require new dynamic channel assignment (DCA) algorithms. This paper examines the impact of dynamic cell sectoring and geometric conditioning on NNAs developed for SCA in omnicell networks with stationary traffic to improve the metrics

  4. An integrated interface for peripheral neural system recording and stimulation: system design, electrical tests and in-vivo results.

    PubMed

    Carboni, Caterina; Bisoni, Lorenzo; Carta, Nicola; Puddu, Roberto; Raspopovic, Stanisa; Navarro, Xavier; Raffo, Luigi; Barbaro, Massimo

    2016-04-01

    The prototype of an electronic bi-directional interface between the Peripheral Nervous System (PNS) and a neuro-controlled hand prosthesis is presented. The system is composed of 2 integrated circuits: a standard CMOS device for neural recording and a HVCMOS device for neural stimulation. The integrated circuits have been realized in 2 different 0.35μ m CMOS processes available from ams. The complete system incorporates 8 channels each including the analog front-end, the A/D conversion, based on a sigma delta architecture and a programmable stimulation module implemented as a 5-bit current DAC; two voltage boosters supply the output stimulation stage with a programmable voltage scalable up to 17V. Successful in-vivo experiments with rats having a TIME electrode implanted in the sciatic nerve were carried out, showing the capability of recording neural signals in the tens of microvolts, with a global noise of 7μ V r m s , and to selectively elicit the tibial and plantar muscles using different active sites of the electrode.

  5. Importance of cochlear health for implant function.

    PubMed

    Pfingst, Bryan E; Zhou, Ning; Colesa, Deborah J; Watts, Melissa M; Strahl, Stefan B; Garadat, Soha N; Schvartz-Leyzac, Kara C; Budenz, Cameron L; Raphael, Yehoash; Zwolan, Teresa A

    2015-04-01

    Amazing progress has been made in providing useful hearing to hearing-impaired individuals using cochlear implants, but challenges remain. One such challenge is understanding the effects of partial degeneration of the auditory nerve, the target of cochlear implant stimulation. Here we review studies from our human and animal laboratories aimed at characterizing the health of the implanted cochlea and the auditory nerve. We use the data on cochlear and neural health to guide rehabilitation strategies. The data also motivate the development of tissue-engineering procedures to preserve or build a healthy cochlea and improve performance obtained by cochlear implant recipients or eventually replace the need for a cochlear implant. This article is part of a Special Issue entitled . Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Audiological outcomes of cochlear implantation in Waardenburg Syndrome

    PubMed Central

    Magalhães, Ana Tereza de Matos; Samuel, Paola Angélica; Goffi-Gomez, Maria Valeria Schimdt; Tsuji, Robinson Koji; Brito, Rubens; Bento, Ricardo Ferreira

    2013-01-01

    Summary Introduction: The most relevant clinical symptom in Waardenburg syndrome is profound bilateral sensorioneural hearing loss. Aim: To characterize and describe hearing outcomes after cochlear implantation in patients with Waardenburg syndrome to improve preoperative expectations. Method: This was an observational and retrospective study of a series of cases. Children who were diagnosed with Waardenburg syndrome and who received a multichannel cochlear implant between March 1999 and July 2012 were included in the study. Intraoperative neural response telemetry, hearing evaluation, speech perception, and speech production data before and after surgery were assessed. Results: During this period, 806 patients received a cochlear implant and 10 of these (1.2%) were diagnosed with Waardenburg syndrome. Eight of the children received a Nucleus 24® implant and 1 child and 1 adult received a DigiSonic SP implant. The mean age at implantation was 44 months among the children. The average duration of use of a cochlear implant at the time of the study was 43 months. Intraoperative neural responses were present in all cases. Patients who could use the speech processor effectively had a pure tone average of 31 dB in free-field conditions. In addition, the MUSS and MAIS questionnaires revealed improvements in speech perception and production. Four patients did not have a good outcome, which might have been associated with ineffective use of the speech processor. Conclusion: Despite the heterogeneity of the group, patients with Waardenburg syndrome who received cochlear implants were found to have hearing thresholds that allowed access to speech sounds. However, patients who received early intervention and rehabilitation showed better evolution of auditory perception. PMID:25992025

  7. Audiological outcomes of cochlear implantation in Waardenburg Syndrome.

    PubMed

    Magalhães, Ana Tereza de Matos; Samuel, Paola Angélica; Goffi-Gomez, Maria Valeria Schimdt; Tsuji, Robinson Koji; Brito, Rubens; Bento, Ricardo Ferreira

    2013-07-01

     The most relevant clinical symptom in Waardenburg syndrome is profound bilateral sensorioneural hearing loss.  To characterize and describe hearing outcomes after cochlear implantation in patients with Waardenburg syndrome to improve preoperative expectations.  This was an observational and retrospective study of a series of cases. Children who were diagnosed with Waardenburg syndrome and who received a multichannel cochlear implant between March 1999 and July 2012 were included in the study. Intraoperative neural response telemetry, hearing evaluation, speech perception, and speech production data before and after surgery were assessed.  During this period, 806 patients received a cochlear implant and 10 of these (1.2%) were diagnosed with Waardenburg syndrome. Eight of the children received a Nucleus 24(®) implant and 1 child and 1 adult received a DigiSonic SP implant. The mean age at implantation was 44 months among the children. The average duration of use of a cochlear implant at the time of the study was 43 months. Intraoperative neural responses were present in all cases. Patients who could use the speech processor effectively had a pure tone average of 31 dB in free-field conditions. In addition, the MUSS and MAIS questionnaires revealed improvements in speech perception and production. Four patients did not have a good outcome, which might have been associated with ineffective use of the speech processor.  Despite the heterogeneity of the group, patients with Waardenburg syndrome who received cochlear implants were found to have hearing thresholds that allowed access to speech sounds. However, patients who received early intervention and rehabilitation showed better evolution of auditory perception.

  8. Auditory brainstem activity and development evoked by apical versus basal cochlear implant electrode stimulation in children.

    PubMed

    Gordon, K A; Papsin, B C; Harrison, R V

    2007-08-01

    The role of apical versus basal cochlear implant electrode stimulation on central auditory development was examined. We hypothesized that, in children with early onset deafness, auditory development evoked by basal electrode stimulation would differ from that evoked more apically. Responses of the auditory nerve and brainstem, evoked by an apical and a basal implant electrode, were measured over the first year of cochlear implant use in 50 children with early onset severe to profound deafness who used hearing aids prior to implantation. Responses at initial stimulation were of larger amplitude and shorter latency when evoked by the apical electrode. No significant effects of residual hearing or age were found on initial response amplitudes or latencies. With implant use, responses evoked by both electrodes showed decreases in wave and interwave latencies reflecting decreased neural conduction time through the brainstem. Apical versus basal differences persisted with implant experience with one exception; eIII-eV interlatency differences decreased with implant use. Acute stimulation shows prolongation of basally versus apically evoked auditory nerve and brainstem responses in children with severe to profound deafness. Interwave latencies reflecting neural conduction along the caudal and rostral portions of the brainstem decreased over the first year of implant use. Differences in neural conduction times evoked by apical versus basal electrode stimulation persisted in the caudal but not rostral brainstem. Activity-dependent changes of the auditory brainstem occur in response to both apical and basal cochlear implant electrode stimulation.

  9. AlN metal-semiconductor field-effect transistors using Si-ion implantation

    NASA Astrophysics Data System (ADS)

    Okumura, Hironori; Suihkonen, Sami; Lemettinen, Jori; Uedono, Akira; Zhang, Yuhao; Piedra, Daniel; Palacios, Tomás

    2018-04-01

    We report on the electrical characterization of Si-ion implanted AlN layers and the first demonstration of metal-semiconductor field-effect transistors (MESFETs) with an ion-implanted AlN channel. The ion-implanted AlN layers with Si dose of 5 × 1014 cm-2 exhibit n-type characteristics after thermal annealing at 1230 °C. The ion-implanted AlN MESFETs provide good drain current saturation and stable pinch-off operation even at 250 °C. The off-state breakdown voltage is 2370 V for drain-to-gate spacing of 25 µm. These results show the great potential of AlN-channel transistors for high-temperature and high-power applications.

  10. Versatile, modular 3D microelectrode arrays for neuronal ensemble recordings: from design to fabrication, assembly, and functional validation in non-human primates.

    PubMed

    Barz, F; Livi, A; Lanzilotto, M; Maranesi, M; Bonini, L; Paul, O; Ruther, P

    2017-06-01

    Application-specific designs of electrode arrays offer an improved effectiveness for providing access to targeted brain regions in neuroscientific research and brain machine interfaces. The simultaneous and stable recording of neuronal ensembles is the main goal in the design of advanced neural interfaces. Here, we describe the development and assembly of highly customizable 3D microelectrode arrays and demonstrate their recording performance in chronic applications in non-human primates. System assembly relies on a microfabricated stacking component that is combined with Michigan-style silicon-based electrode arrays interfacing highly flexible polyimide cables. Based on the novel stacking component, the lead time for implementing prototypes with altered electrode pitches is minimal. Once the fabrication and assembly accuracy of the stacked probes have been characterized, their recording performance is assessed during in vivo chronic experiments in awake rhesus macaques (Macaca mulatta) trained to execute reaching-grasping motor tasks. Using a single set of fabrication tools, we implemented three variants of the stacking component for electrode distances of 250, 300 and 350 µm in the stacking direction. We assembled neural probes with up to 96 channels and an electrode density of 98 electrodes mm -2 . Furthermore, we demonstrate that the shank alignment is accurate to a few µm at an angular alignment better than 1°. Three 64-channel probes were chronically implanted in two monkeys providing single-unit activity on more than 60% of all channels and excellent recording stability. Histological tissue sections, obtained 52 d after implantation from one of the monkeys, showed minimal tissue damage, in accordance with the high quality and stability of the recorded neural activity. The versatility of our fabrication and assembly approach should significantly support the development of ideal interface geometries for a broad spectrum of applications. With the

  11. Versatile, modular 3D microelectrode arrays for neuronal ensemble recordings: from design to fabrication, assembly, and functional validation in non-human primates

    NASA Astrophysics Data System (ADS)

    Barz, F.; Livi, A.; Lanzilotto, M.; Maranesi, M.; Bonini, L.; Paul, O.; Ruther, P.

    2017-06-01

    Objective. Application-specific designs of electrode arrays offer an improved effectiveness for providing access to targeted brain regions in neuroscientific research and brain machine interfaces. The simultaneous and stable recording of neuronal ensembles is the main goal in the design of advanced neural interfaces. Here, we describe the development and assembly of highly customizable 3D microelectrode arrays and demonstrate their recording performance in chronic applications in non-human primates. Approach. System assembly relies on a microfabricated stacking component that is combined with Michigan-style silicon-based electrode arrays interfacing highly flexible polyimide cables. Based on the novel stacking component, the lead time for implementing prototypes with altered electrode pitches is minimal. Once the fabrication and assembly accuracy of the stacked probes have been characterized, their recording performance is assessed during in vivo chronic experiments in awake rhesus macaques (Macaca mulatta) trained to execute reaching-grasping motor tasks. Main results. Using a single set of fabrication tools, we implemented three variants of the stacking component for electrode distances of 250, 300 and 350 µm in the stacking direction. We assembled neural probes with up to 96 channels and an electrode density of 98 electrodes mm-2. Furthermore, we demonstrate that the shank alignment is accurate to a few µm at an angular alignment better than 1°. Three 64-channel probes were chronically implanted in two monkeys providing single-unit activity on more than 60% of all channels and excellent recording stability. Histological tissue sections, obtained 52 d after implantation from one of the monkeys, showed minimal tissue damage, in accordance with the high quality and stability of the recorded neural activity. Significance. The versatility of our fabrication and assembly approach should significantly support the development of ideal interface geometries for a broad

  12. Production and characterization of immortal human neural stem cell line with multipotent differentiation property.

    PubMed

    Kim, Seung U; Nagai, Atsushi; Nakagawa, Eiji; Choi, Hyun B; Bang, Jung H; Lee, Hong J; Lee, Myung A; Lee, Yong B; Park, In H

    2008-01-01

    We document the protocols and methods for the production of immortalized cell lines of human neural stem cells from the human fetal central nervous system (CNS) cells by using a retroviral vector encoding v-myc oncogene. One of the human neural stem cell lines (HB1.F3) was found to express nestin and other specific markers for human neural stem cells, giving rise to three fundamental cell types of the CNS: neurons, astrocytes, and oligodendrocytes. After transplantation into the brain of mouse model of stroke, implanted human neural stem cells were observed to migrate extensively from the site of implantation into other anatomical sites and to differentiate into neurons and glial cells.

  13. Novel implant design improves implant survival in multirooted extraction sites: a preclinical pilot study.

    PubMed

    Sivan-Gildor, Adi; Machtei, Eli E; Gabay, Eran; Frankenthal, Shai; Levin, Liran; Suzuki, Marcelo; Coelho, Paulo G; Zigdon-Giladi, Hadar

    2014-10-01

    The primary aim is to evaluate clinical, radiographic, and histologic parameters of novel implants with "three roots" design that were inserted into fresh multirooted extraction sockets. A secondary aim is to compare this new implant to standard root-form dental implants. Immediate implantation of novel or standard design 6 × 6-mm implants was performed bilaterally into multirooted sockets in mandibles of mini-pigs. Twelve weeks later, clinical, radiographic, stability, histomorphometric, and microcomputed tomography (micro-CT) analyses were performed. Survival rates were significantly higher in the test implants compared with control (92.8% versus 33.3%, respectively; P <0.001). Bone loss was greater in the control compared with the test by sounding (mean 3.42 ± 0.68 versus 1.96 ± 0.34 mm) and radiography (mean 3.35 ± 0.62 versus 2.27 ± 0.33 mm). Histologic and micro-CT analyses demonstrated bone fill in the inner part of the test implants. Moreover, bone-to-implant contact was higher in the test implants (55.50% ± 3.68% versus 42.47% ± 9.89%). Contrary to the clinical, radiographic, and histomorphometric results, resonance frequency analysis measurements were greater in the control group (77.74 ± 3.21 implant stability quotient [ISQ]) compared with the test group (31.09 ± 0.28 ISQ), P = 0.008. The novel design implants resulted in significantly greater survival rate in multirooted extraction sites. Further studies will be required to validate these findings.

  14. Utilising reinforcement learning to develop strategies for driving auditory neural implants.

    PubMed

    Lee, Geoffrey W; Zambetta, Fabio; Li, Xiaodong; Paolini, Antonio G

    2016-08-01

    In this paper we propose a novel application of reinforcement learning to the area of auditory neural stimulation. We aim to develop a simulation environment which is based off real neurological responses to auditory and electrical stimulation in the cochlear nucleus (CN) and inferior colliculus (IC) of an animal model. Using this simulator we implement closed loop reinforcement learning algorithms to determine which methods are most effective at learning effective acoustic neural stimulation strategies. By recording a comprehensive set of acoustic frequency presentations and neural responses from a set of animals we created a large database of neural responses to acoustic stimulation. Extensive electrical stimulation in the CN and the recording of neural responses in the IC provides a mapping of how the auditory system responds to electrical stimuli. The combined dataset is used as the foundation for the simulator, which is used to implement and test learning algorithms. Reinforcement learning, utilising a modified n-Armed Bandit solution, is implemented to demonstrate the model's function. We show the ability to effectively learn stimulation patterns which mimic the cochlea's ability to covert acoustic frequencies to neural activity. Time taken to learn effective replication using neural stimulation takes less than 20 min under continuous testing. These results show the utility of reinforcement learning in the field of neural stimulation. These results can be coupled with existing sound processing technologies to develop new auditory prosthetics that are adaptable to the recipients current auditory pathway. The same process can theoretically be abstracted to other sensory and motor systems to develop similar electrical replication of neural signals.

  15. Incorporating an optical waveguide into a neural interface

    DOEpatents

    Tolosa, Vanessa; Delima, Terri L.; Felix, Sarah H.; Pannu, Satinderpall S.; Shah, Kedar G.; Sheth, Heeral; Tooker, Angela C.

    2016-11-08

    An optical waveguide integrated into a multielectrode array (MEA) neural interface includes a device body, at least one electrode in the device body, at least one electrically conducting lead coupled to the at least one electrode, at least one optical channel in the device body, and waveguide material in the at least one optical channel. The fabrication of a neural interface device includes the steps of providing a device body, providing at least one electrode in the device body, providing at least one electrically conducting lead coupled to the at least one electrode, providing at least one optical channel in the device body, and providing a waveguide material in the at least one optical channel.

  16. A Bionic Neural Link for peripheral nerve repair.

    PubMed

    Xu, Yong Ping; Yen, Shih-Cheng; Ng, Kian Ann; Liu, Xu; Tan, Ter Chyan

    2012-01-01

    Peripheral nerve injuries with large gaps and long nerve regrowth paths are difficult to repair using existing surgical techniques, due to nerve degeneration and muscle atrophy. This paper proposes a Bionic Neural Link (BNL) as an alternative way for peripheral nerve repair. The concept of the BNL is described, along with the hypothetical benefits. A prototype monolithic single channel BNL has been developed, which consists of 16 neural recording channels and one stimulation channel, and is implemented in a 0.35-µm CMOS technology. The BNL has been tested in in-vivo animal experiments. Full function of the BNL chip has been demonstrated.

  17. A novel speech-processing strategy incorporating tonal information for cochlear implants.

    PubMed

    Lan, N; Nie, K B; Gao, S K; Zeng, F G

    2004-05-01

    Good performance in cochlear implant users depends in large part on the ability of a speech processor to effectively decompose speech signals into multiple channels of narrow-band electrical pulses for stimulation of the auditory nerve. Speech processors that extract only envelopes of the narrow-band signals (e.g., the continuous interleaved sampling (CIS) processor) may not provide sufficient information to encode the tonal cues in languages such as Chinese. To improve the performance in cochlear implant users who speak tonal language, we proposed and developed a novel speech-processing strategy, which extracted both the envelopes of the narrow-band signals and the fundamental frequency (F0) of the speech signal, and used them to modulate both the amplitude and the frequency of the electrical pulses delivered to stimulation electrodes. We developed an algorithm to extract the fundatmental frequency and identified the general patterns of pitch variations of four typical tones in Chinese speech. The effectiveness of the extraction algorithm was verified with an artificial neural network that recognized the tonal patterns from the extracted F0 information. We then compared the novel strategy with the envelope-extraction CIS strategy in human subjects with normal hearing. The novel strategy produced significant improvement in perception of Chinese tones, phrases, and sentences. This novel processor with dynamic modulation of both frequency and amplitude is encouraging for the design of a cochlear implant device for sensorineurally deaf patients who speak tonal languages.

  18. Binaural unmasking of multi-channel stimuli in bilateral cochlear implant users.

    PubMed

    Van Deun, Lieselot; van Wieringen, Astrid; Francart, Tom; Büchner, Andreas; Lenarz, Thomas; Wouters, Jan

    2011-10-01

    Previous work suggests that bilateral cochlear implant users are sensitive to interaural cues if experimental speech processors are used to preserve accurate interaural information in the electrical stimulation pattern. Binaural unmasking occurs in adults and children when an interaural delay is applied to the envelope of a high-rate pulse train. Nevertheless, for speech perception, binaural unmasking benefits have not been demonstrated consistently, even with coordinated stimulation at both ears. The present study aimed at bridging the gap between basic psychophysical performance on binaural signal detection tasks on the one hand and binaural perception of speech in noise on the other hand. Therefore, binaural signal detection was expanded to multi-channel stimulation and biologically relevant interaural delays. A harmonic complex, consisting of three sinusoids (125, 250, and 375 Hz), was added to three 125-Hz-wide noise bands centered on the sinusoids. When an interaural delay of 700 μs was introduced, an average BMLD of 3 dB was established. Outcomes are promising in view of real-life benefits. Future research should investigate the generalization of the observed benefits for signal detection to speech perception in everyday listening situations and determine the importance of coordination of bilateral speech processors and accentuation of envelope cues.

  19. In vivo evaluation of mastication noise reduction for dual channel implantable microphone.

    PubMed

    Woo, SeongTak; Jung, EuiSung; Lim, HyungGyu; Lee, Jang Woo; Seong, Ki Woong; Won, Chul Ho; Kim, Myoung Nam; Cho, Jin Ho; Lee, Jyung Hyun

    2014-01-01

    Input for fully implantable hearing devices (FIHDs) is provided by an implantable microphone under the skin of the temporal bone. However, the implanted microphone can be affected when the FIHDs user chews. In this paper, a dual implantable microphone was designed that can filter out the noise from mastication. For the in vivo experiment, a fabricated microphone was implanted in a rabbit. Pure-tone sounds of 1 kHz through a standard speaker were applied to the rabbit, which was given food simultaneously. To evaluate noise reduction, the measured signals were processed using a MATLAB program based adaptive filter. To verify the proposed method, the correlation coefficients and signal to-noise ratio before and after signal processing were calculated. By comparing the results, signal-to-noise ratio and correlation coefficients are enhanced by 6.07dB and 0.529 respectively.

  20. Simplified Design Equations for Class-E Neural Prosthesis Transmitters

    PubMed Central

    Troyk, Philip; Hu, Zhe

    2013-01-01

    Extreme miniaturization of implantable electronic devices is recognized as essential for the next generation of neural prostheses, owing to the need for minimizing the damage and disruption of the surrounding neural tissue. Transcutaneous power and data transmission via a magnetic link remains the most effective means of powering and controlling implanted neural prostheses. Reduction in the size of the coil, within the neural prosthesis, demands the generation of a high-intensity radio frequency magnetic field from the extracoporeal transmitter. The Class-E power amplifier circuit topology has been recognized as a highly effective means of producing large radio frequency currents within the transmitter coil. Unfortunately, design of a Class-E circuit is most often fraught by the need to solve a complex set of equations so as to implement both the zero-voltage-switching and zero-voltage-derivative-switching conditions that are required for efficient operation. This paper presents simple explicit design equations for designing the Class-E circuit topology. Numerical design examples are presented to illustrate the design procedure. PMID:23292784

  1. A Streaming PCA VLSI Chip for Neural Data Compression.

    PubMed

    Wu, Tong; Zhao, Wenfeng; Guo, Hongsun; Lim, Hubert H; Yang, Zhi

    2017-12-01

    Neural recording system miniaturization and integration with low-power wireless technologies require compressing neural data before transmission. Feature extraction is a procedure to represent data in a low-dimensional space; its integration into a recording chip can be an efficient approach to compress neural data. In this paper, we propose a streaming principal component analysis algorithm and its microchip implementation to compress multichannel local field potential (LFP) and spike data. The circuits have been designed in a 65-nm CMOS technology and occupy a silicon area of 0.06 mm. Throughout the experiments, the chip compresses LFPs by 10 at the expense of as low as 1% reconstruction errors and 144-nW/channel power consumption; for spikes, the achieved compression ratio is 25 with 8% reconstruction errors and 3.05-W/channel power consumption. In addition, the algorithm and its hardware architecture can swiftly adapt to nonstationary spiking activities, which enables efficient hardware sharing among multiple channels to support a high-channel count recorder.

  2. Fundamental frequency discrimination and speech perception in noise in cochlear implant simulationsa)

    PubMed Central

    Carroll, Jeff; Zeng, Fan-Gang

    2007-01-01

    Increasing the number of channels at low frequencies improves discrimination of fundamental frequency (F0) in cochlear implants [Geurts and Wouters 2004]. We conducted three experiments to test whether improved F0 discrimination can be translated into increased speech intelligibility in noise in a cochlear implant simulation. The first experiment measured F0 discrimination and speech intelligibility in quiet as a function of channel density over different frequency regions. The results from this experiment showed a tradeoff in performance between F0 discrimination and speech intelligibility with a limited number of channels. The second experiment tested whether improved F0 discrimination and optimizing this tradeoff could improve speech performance with a competing talker. However, improved F0 discrimination did not improve speech intelligibility in noise. The third experiment identified the critical number of channels needed at low frequencies to improve speech intelligibility in noise. The result showed that, while 16 channels below 500 Hz were needed to observe any improvement in speech intelligibility in noise, even 32 channels did not achieve normal performance. Theoretically, these results suggest that without accurate spectral coding, F0 discrimination and speech perception in noise are two independent processes. Practically, the present results illustrate the need to increase the number of independent channels in cochlear implants. PMID:17604581

  3. Cochlear implant in Hong Kong Cantonese.

    PubMed

    Tang, S O; Luk, W S; Lau, C C; So, K W; Wong, C M; Yiu, M L; Kwok, C L

    1990-11-01

    Cochlear implant surgery was performed in four Cantonese-speaking postlingually deaf Chinese adults, using the House/3M single channel device. This article outlines the methodology, including preoperative assessment and postoperative rehabilitation; and explains the necessary modifications in speech and audiologic work-up in Cantonese-speaking patients. Salient features of Cantonese phonetics, especially its tonal characteristics, are described. The findings of the study are presented. The results of the cochlear implant would suggest a performance superior to that of the hearing aid. Furthermore, the cochlear implant is able to detect tonal cues. This quality of the cochlear implant may prove to be a valuable asset to a tonal language-speaking cochlear implantee.

  4. Artificial neural network modeling of a deflector in a grooved channel as well as optimization of its effective parameters

    NASA Astrophysics Data System (ADS)

    Abdollahi, Azita; Shams, Mehrzad; Abdollahi, Anita

    2018-01-01

    One of methods available to increase the rate of heat transfer in channels with parallel plates is making grooves in them. But, the fundamental problem of this method is the formation of stagnation zone in the grooves and as a result formation a zone with low energy transfer. In this paper, the effect of placing curved deflectors (geometries with elliptical forms) in channel on thermal and hydraulic characteristic of the fluid flow- with the aim of directing of the flow into the grooves and as a result increasing the rate of heat transfer in this zone- are investigated and heat transfer coefficient and pressure drop are calculated for different values of Reynolds number and geometrical parameters of the deflector (its small and large radiuses). The results show that the presence of the deflector in the channel significantly increases the heat transfer rate compare to the channel without deflector. Of course, it should be noted that this work also increases the pressure drop. So, finally in order to determine configurations of the deflector causing minimum pressure drop, maximum Nusselt number or a balance between them, optimization algorithm consisting of artificial neural network and multi-objective genetic algorithm was utilized to calculate the optimal values of these parameters.

  5. Ultrasonic implant site preparation using piezosurgery: a multicenter case series study analyzing 3,579 implants with a 1- to 3-year follow-up.

    PubMed

    Vercellotti, Tomaso; Stacchi, Claudio; Russo, Crescenzo; Rebaudi, Alberto; Vincenzi, Giampaolo; Pratella, Umberto; Baldi, Domenico; Mozzati, Marco; Monagheddu, Chiara; Sentineri, Rosario; Cuneo, Tommaso; Di Alberti, Luca; Carossa, Stefano; Schierano, Gianmario

    2014-01-01

    This multicenter case series introduces an innovative ultrasonic implant site preparation (UISP) technique as an alternative to the use of traditional rotary instruments. A total of 3,579 implants were inserted in 1,885 subjects, and the sites were prepared using a specific ultrasonic device with a 1- to 3-year follow-up. No surgical complications related to the UISP protocol were reported for any of the implant sites. Seventy-eight implants (59 maxillary, 19 mandibular) failed within 5 months of insertion, for an overall osseointegration percentage of 97.82% (97.14% maxilla, 98.75% mandible). Three maxillary implants failed after 3 years of loading, with an overall implant survival rate of 97.74% (96.99% maxilla, 98.75% mandible).

  6. Neurosecurity: security and privacy for neural devices.

    PubMed

    Denning, Tamara; Matsuoka, Yoky; Kohno, Tadayoshi

    2009-07-01

    An increasing number of neural implantable devices will become available in the near future due to advances in neural engineering. This discipline holds the potential to improve many patients' lives dramatically by offering improved-and in some cases entirely new-forms of rehabilitation for conditions ranging from missing limbs to degenerative cognitive diseases. The use of standard engineering practices, medical trials, and neuroethical evaluations during the design process can create systems that are safe and that follow ethical guidelines; unfortunately, none of these disciplines currently ensure that neural devices are robust against adversarial entities trying to exploit these devices to alter, block, or eavesdrop on neural signals. The authors define "neurosecurity"-a version of computer science security principles and methods applied to neural engineering-and discuss why neurosecurity should be a critical consideration in the design of future neural devices.

  7. A 64-channel ultra-low power system-on-chip for local field and action potentials recording

    NASA Astrophysics Data System (ADS)

    Rodríguez-Pérez, Alberto; Delgado-Restituto, Manuel; Darie, Angela; Soto-Sánchez, Cristina; Fernández-Jover, Eduardo; Rodríguez-Vázquez, Ángel

    2015-06-01

    This paper reports an integrated 64-channel neural recording sensor. Neural signals are acquired, filtered, digitized and compressed in the channels. Additionally, each channel implements an auto-calibration mechanism which configures the transfer characteristics of the recording site. The system has two transmission modes; in one case the information captured by the channels is sent as uncompressed raw data; in the other, feature vectors extracted from the detected neural spikes are released. Data streams coming from the channels are serialized by an embedded digital processor. Experimental results, including in vivo measurements, show that the power consumption of the complete system is lower than 330μW.

  8. Implant Mandibular Overdentures Retained by Immediately Loaded Implants: A 1-Year Randomized Trial Comparing the Clinical and Radiographic Outcomes Between Mini Dental Implants and Standard-Sized Implants.

    PubMed

    Zygogiannis, Kostas; Aartman, Irene Ha; Parsa, Azin; Tahmaseb, Ali; Wismeijer, Daniel

    The aim of this 1-year randomized trial was to evaluate and compare the clinical and radiographic performance of four immediately loaded mini dental implants (MDIs) and two immediately loaded standard-sized tissue-level (STL) implants, placed in the interforaminal region of the mandible and used to retain mandibular overdentures (IODs) in completely edentulous patients. A total of 50 completely edentulous patients wearing conventional maxillary dentures and complaining about insufficient retention of their mandibular dentures were divided into two groups; 25 patients received four MDIs and 25 patients received two STL implants. The marginal bone loss (MBL) at the mesial and distal sides of each implant was assessed by means of standardized intraoral radiographs after a period of 1 year. Implant success and survival rates were also calculated. Immediate loading was possible for all patients in the first group. In the second group, an immediate loading protocol could not be applied for 10 patients. These patients were treated with a delayed loading protocol. A mean MBL of 0.42 ± 0.56 mm for the MDIs and 0.54 ± 0.49 mm for the immediately loaded STL implants was recorded at the end of the evaluation period. There was no statistically significant difference between the MDIs and the immediately loaded STL implants. Two MDIs failed, resulting in a survival rate of 98%. The success rate was 91%. For the immediately loaded conventional implants, the survival rate was 100% and the success rate 96.7% after 1 year of function. However, in 10 patients, the immediate loading protocol could not be followed. Considering the limitations of this short-term clinical study, immediate loading of four unsplinted MDIs or two splinted STL implants to retain mandibular overdentures seems to be a feasible treatment option. The marginal bone level changes around the MDIs were well within the clinically acceptable range.

  9. Cd ion implantation in AlN

    NASA Astrophysics Data System (ADS)

    Miranda, S. M. C.; Franco, N.; Alves, E.; Lorenz, K.

    2012-10-01

    AlN thin films were implanted with cadmium, to fluences of 1 × 1013 and 8 × 1014 at/cm2. The implanted samples were annealed at 950 °C under flowing nitrogen. Although implantation damage in AlN is known to be extremely stable the crystal could be fully recovered at low fluences. At high fluences the implantation damage was only partially removed. Implantation defects cause an expansion of the c-lattice parameter. For the high fluence sample the lattice site location of the ions was studied by Rutherford Backscattering/Channelling Spectrometry. Cd ions are found to be incorporated in substitutional Al sites in the crystal and no significant diffusion is seen upon thermal annealing. The observed high solubility limit and site stability are prerequisite for using Cd as p-type dopant in AlN.

  10. Delay-distribution-dependent H∞ state estimation for delayed neural networks with (x,v)-dependent noises and fading channels.

    PubMed

    Sheng, Li; Wang, Zidong; Tian, Engang; Alsaadi, Fuad E

    2016-12-01

    This paper deals with the H ∞ state estimation problem for a class of discrete-time neural networks with stochastic delays subject to state- and disturbance-dependent noises (also called (x,v)-dependent noises) and fading channels. The time-varying stochastic delay takes values on certain intervals with known probability distributions. The system measurement is transmitted through fading channels described by the Rice fading model. The aim of the addressed problem is to design a state estimator such that the estimation performance is guaranteed in the mean-square sense against admissible stochastic time-delays, stochastic noises as well as stochastic fading signals. By employing the stochastic analysis approach combined with the Kronecker product, several delay-distribution-dependent conditions are derived to ensure that the error dynamics of the neuron states is stochastically stable with prescribed H ∞ performance. Finally, a numerical example is provided to illustrate the effectiveness of the obtained results. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Characterization of Defects in N-type 4H-SiC After High-Energy N Ion Implantation by RBS-Channeling and Raman Spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kummari, Venkata C.; Reinert, Tilo; Jiang, Weilin

    Implantation with 1 MeV N ions was performed at room temperature in n-type 4H-SiC(0001) to four implantation fluences (or doses in dpa (displacements per atom) at the damage peak) of 1.5×1013(0.0034), 7.8×1013(0.018), 1.5×1014(0.034), and 7.8×1014(0.18) ions/cm2, respectively. The evolution of disorder was studied using Rutherford backscattering spectrometry in channeling mode (RBS-C) and Raman spectroscopy. The disorder in the Si sub-lattice was found to be less than 10% for the dpa of 0.0034 and 0.0178 and increased to 40% and 60% for the dpa of 0.034 and 0.178 respectively. Raman Spectroscopy was performed using a green laser of wavelength 532 nmmore » as excitation source. The normalized Raman Intensity, In shows disorder of 41%, 69%, 77% and 100% for the dpa of 0.0034, 0.017, 0.034 and 0.178 respectively. In this paper, the characterizations of the defects produced due to the Nitrogen implantation in 4H-SiC are presented and the results are discussed.« less

  12. Transfer couplings and hindrance far below the barrier for 40 Ca + 96 Zr

    DOE PAGES

    Stefanini, A. M.; Montagnoli, G.; Esbensen, H.; ...

    2015-01-29

    The sub-barrier fusion excitation function of 40Ca + 96Zr has been measured down to cross sections ≃2.4µb, i.e. two orders of magnitude smaller than obtained in the previous experiment, where the sub-barrier fusion of this system was found to be greatly enhanced with respect to 40Ca + 90Zr, and the need of coupling to transfer channels was suggested. The purpose of this work was to investigate the behavior of 40Ca + 96Zr fusion far below the barrier. The smooth trend of the excitation function has been found to continue, and the logarithmic slope increases very slowly. No indication of hindrancemore » shows up, and a comparison with 48Ca + 96Zr is very useful in this respect. A new CC analysis of the complete excitation function has been performed, including explicitly one- and two-nucleon Q >0 transfer channels. Such transfer couplings bring significant cross section enhancements, even at the level of a few µb. Locating the hindrance threshold, if any, in 40Ca + 96Zr would require challenging measurements of cross sections in the sub-µb range.« less

  13. Modification of anti-bacterial surface properties of textile polymers by vacuum arc ion source implantation

    NASA Astrophysics Data System (ADS)

    Nikolaev, A. G.; Yushkov, G. Yu.; Oks, E. M.; Oztarhan, A.; Akpek, A.; Hames-Kocabas, E.; Urkac, E. S.; Brown, I. G.

    2014-08-01

    Ion implantation provides an important technology for the modification of material surface properties. The vacuum arc ion source is a unique instrument for the generation of intense beams of metal ions as well as gaseous ions, including mixed metal-gas beams with controllable metal:gas ion ratio. Here we describe our exploratory work on the application of vacuum arc ion source-generated ion beams for ion implantation into polymer textile materials for modification of their biological cell compatibility surface properties. We have investigated two specific aspects of cell compatibility: (i) enhancement of the antibacterial characteristics (we chose to use Staphylococcus aureus bacteria) of ion implanted polymer textile fabric, and (ii) the "inverse" concern of enhancement of neural cell growth rate (we chose Rat B-35 neuroblastoma cells) on ion implanted polymer textile. The results of both investigations were positive, with implantation-generated antibacterial efficiency factor up to about 90%, fully comparable to alternative conventional (non-implantation) approaches and with some potentially important advantages over the conventional approach; and with enhancement of neural cell growth rate of up to a factor of 3.5 when grown on suitably implanted polymer textile material.

  14. Energy harvesting from cerebrospinal fluid pressure fluctuations for self-powered neural implants.

    PubMed

    Beker, Levent; Benet, Arnau; Meybodi, Ali Tayebi; Eovino, Ben; Pisano, Albert P; Lin, Liwei

    2017-06-01

    In this paper, a novel method to generate electrical energy by converting available mechanical energy from pressure fluctuations of the cerebrospinal fluid within lateral ventricles of the brain is presented. The generated electrical power can be supplied to the neural implants and either eliminate their battery need or extend the battery lifespan. A diaphragm type harvester comprised of piezoelectric material is utilized to convert the pressure fluctuations to electrical energy. The pressure fluctuations cause the diaphragm to bend, and the strained piezoelectric materials generate electricity. In the framework of this study, an energy harvesting structure having a diameter of 2.5 mm was designed and fabricated using microfabrication techniques. A 1:1 model of lateral ventricles was 3D-printed from raw MRI images to characterize the harvester. Experimental results show that a maximum power of 0.62 nW can be generated from the harvester under similar physical conditions in lateral ventricles which corresponds to energy density of 12.6 nW/cm 2 . Considering the available area within the lateral ventricles and the size of harvesters that can be built using microfabrication techniques it is possible to amplify to power up to 26 nW. As such, the idea of generating electrical energy by making use of pressure fluctuations within brain is demonstrated in this work via the 3D-printed model system.

  15. Role of Cyclic Nucleotide-Gated Channels in the Modulation of Mouse Hippocampal Neurogenesis

    PubMed Central

    Podda, Maria Vittoria; Piacentini, Roberto; Barbati, Saviana Antonella; Mastrodonato, Alessia; Puzzo, Daniela; D’Ascenzo, Marcello; Leone, Lucia; Grassi, Claudio

    2013-01-01

    Neural stem cells generate neurons in the hippocampal dentate gyrus in mammals, including humans, throughout adulthood. Adult hippocampal neurogenesis has been the focus of many studies due to its relevance in processes such as learning and memory and its documented impairment in some neurodegenerative diseases. However, we are still far from having a complete picture of the mechanism regulating this process. Our study focused on the possible role of cyclic nucleotide-gated (CNG) channels. These voltage-independent channels activated by cyclic nucleotides, first described in retinal and olfactory receptors, have been receiving increasing attention for their involvement in several brain functions. Here we show that the rod-type, CNGA1, and olfactory-type, CNGA2, subunits are expressed in hippocampal neural stem cells in culture and in situ in the hippocampal neurogenic niche of adult mice. Pharmacological blockade of CNG channels did not affect cultured neural stem cell proliferation but reduced their differentiation towards the neuronal phenotype. The membrane permeant cGMP analogue, 8-Br-cGMP, enhanced neural stem cell differentiation to neurons and this effect was prevented by CNG channel blockade. In addition, patch-clamp recording from neuron-like differentiating neural stem cells revealed cGMP-activated currents attributable to ion flow through CNG channels. The current work provides novel insights into the role of CNG channels in promoting hippocampal neurogenesis, which may prove to be relevant for stem cell-based treatment of cognitive impairment and brain damage. PMID:23991183

  16. An experimental vestibular neural prosthesis: design and preliminary results with rhesus monkeys stimulated with modulated pulses.

    PubMed

    Nie, Kaibao; Ling, Leo; Bierer, Steven M; Kaneko, Chris R S; Fuchs, Albert F; Oxford, Trey; Rubinstein, Jay T; Phillips, James O

    2013-06-01

    A vestibular neural prosthesis was designed on the basis of a cochlear implant for treatment of Meniere's disease and other vestibular disorders. Computer control software was developed to generate patterned pulse stimuli for exploring optimal parameters to activate the vestibular nerve. Two rhesus monkeys were implanted with the prototype vestibular prosthesis and they were behaviorally evaluated post implantation surgery. Horizontal and vertical eye movement responses to patterned electrical pulse stimulations were collected on both monkeys. Pulse amplitude modulated (PAM) and pulse rate modulated (PRM) trains were applied to the lateral canal of each implanted animal. Robust slow-phase nystagmus responses following the PAM or PRM modulation pattern were observed in both implanted monkeys in the direction consistent with the activation of the implanted canal. Both PAM and PRM pulse trains can elicit a significant amount of in-phase modulated eye velocity changes and they could potentially be used for efficiently coding head rotational signals in future vestibular neural prostheses.

  17. A closed-loop compressive-sensing-based neural recording system.

    PubMed

    Zhang, Jie; Mitra, Srinjoy; Suo, Yuanming; Cheng, Andrew; Xiong, Tao; Michon, Frederic; Welkenhuysen, Marleen; Kloosterman, Fabian; Chin, Peter S; Hsiao, Steven; Tran, Trac D; Yazicioglu, Firat; Etienne-Cummings, Ralph

    2015-06-01

    This paper describes a low power closed-loop compressive sensing (CS) based neural recording system. This system provides an efficient method to reduce data transmission bandwidth for implantable neural recording devices. By doing so, this technique reduces a majority of system power consumption which is dissipated at data readout interface. The design of the system is scalable and is a viable option for large scale integration of electrodes or recording sites onto a single device. The entire system consists of an application-specific integrated circuit (ASIC) with 4 recording readout channels with CS circuits, a real time off-chip CS recovery block and a recovery quality evaluation block that provides a closed feedback to adaptively adjust compression rate. Since CS performance is strongly signal dependent, the ASIC has been tested in vivo and with standard public neural databases. Implemented using efficient digital circuit, this system is able to achieve >10 times data compression on the entire neural spike band (500-6KHz) while consuming only 0.83uW (0.53 V voltage supply) additional digital power per electrode. When only the spikes are desired, the system is able to further compress the detected spikes by around 16 times. Unlike other similar systems, the characteristic spikes and inter-spike data can both be recovered which guarantes a >95% spike classification success rate. The compression circuit occupied 0.11mm(2)/electrode in a 180nm CMOS process. The complete signal processing circuit consumes <16uW/electrode. Power and area efficiency demonstrated by the system make it an ideal candidate for integration into large recording arrays containing thousands of electrode. Closed-loop recording and reconstruction performance evaluation further improves the robustness of the compression method, thus making the system more practical for long term recording.

  18. Cognitive Neural Prosthetics

    PubMed Central

    Andersen, Richard A.; Hwang, Eun Jung; Mulliken, Grant H.

    2010-01-01

    The cognitive neural prosthetic (CNP) is a very versatile method for assisting paralyzed patients and patients with amputations. The CNP records the cognitive state of the subject, rather than signals strictly related to motor execution or sensation. We review a number of high-level cortical signals and their application for CNPs, including intention, motor imagery, decision making, forward estimation, executive function, attention, learning, and multi-effector movement planning. CNPs are defined by the cognitive function they extract, not the cortical region from which the signals are recorded. However, some cortical areas may be better than others for particular applications. Signals can also be extracted in parallel from multiple cortical areas using multiple implants, which in many circumstances can increase the range of applications of CNPs. The CNP approach relies on scientific understanding of the neural processes involved in cognition, and many of the decoding algorithms it uses also have parallels to underlying neural circuit functions. PMID:19575625

  19. Elastomeric and soft conducting microwires for implantable neural interfaces

    PubMed Central

    Kolarcik, Christi L.; Luebben, Silvia D.; Sapp, Shawn A.; Hanner, Jenna; Snyder, Noah; Kozai, Takashi D.Y.; Chang, Emily; Nabity, James A.; Nabity, Shawn T.; Lagenaur, Carl F.; Cui, X. Tracy

    2015-01-01

    Current designs for microelectrodes used for interfacing with the nervous system elicit a characteristic inflammatory response that leads to scar tissue encapsulation, electrical insulation of the electrode from the tissue and ultimately failure. Traditionally, relatively stiff materials like tungsten and silicon are employed which have mechanical properties several orders of magnitude different from neural tissue. This mechanical mismatch is thought to be a major cause of chronic inflammation and degeneration around the device. In an effort to minimize the disparity between neural interface devices and the brain, novel soft electrodes consisting of elastomers and intrinsically conducting polymers were fabricated. The physical, mechanical and electrochemical properties of these materials were extensively characterized to identify the formulations with the optimal combination of parameters including Young’s modulus, elongation at break, ultimate tensile strength, conductivity, impedance and surface charge injection. Our final electrode has a Young’s modulus of 974 kPa which is five orders of magnitude lower than tungsten and significantly lower than other polymer-based neural electrode materials. In vitro cell culture experiments demonstrated the favorable interaction between these soft materials and neurons, astrocytes and microglia, with higher neuronal attachment and a two-fold reduction in inflammatory microglia attachment on soft devices compared to stiff controls. Surface immobilization of neuronal adhesion proteins on these microwires further improved the cellular response. Finally, in vivo electrophysiology demonstrated the functionality of the elastomeric electrodes in recording single unit activity in the rodent visual cortex. The results presented provide initial evidence in support of the use of soft materials in neural interface applications. PMID:25993261

  20. OptoZIF Drive: a 3D printed implant and assembly tool package for neural recording and optical stimulation in freely moving mice

    NASA Astrophysics Data System (ADS)

    Freedman, David S.; Schroeder, Joseph B.; Telian, Gregory I.; Zhang, Zhengyang; Sunil, Smrithi; Ritt, Jason T.

    2016-12-01

    Objective. Behavioral neuroscience studies in freely moving rodents require small, light-weight implants to facilitate neural recording and stimulation. Our goal was to develop an integrated package of 3D printed parts and assembly aids for labs to rapidly fabricate, with minimal training, an implant that combines individually positionable microelectrodes, an optical fiber, zero insertion force (ZIF-clip) headstage connection, and secondary recording electrodes, e.g. for electromyography (EMG). Approach. Starting from previous implant designs that position recording electrodes using a control screw, we developed an implant where the main drive body, protective shell, and non-metal components of the microdrives are 3D printed in parallel. We compared alternative shapes and orientations of circuit boards for electrode connection to the headstage, in terms of their size, weight, and ease of wire insertion. We iteratively refined assembly methods, and integrated additional assembly aids into the 3D printed casing. Main results. We demonstrate the effectiveness of the OptoZIF Drive by performing real time optogenetic feedback in behaving mice. A novel feature of the OptoZIF Drive is its vertical circuit board, which facilities direct ZIF-clip connection. This feature requires angled insertion of an optical fiber that still can exit the drive from the center of a ring of recording electrodes. We designed an innovative 2-part protective shell that can be installed during the implant surgery to facilitate making additional connections to the circuit board. We use this feature to show that facial EMG in mice can be used as a control signal to lock stimulation to the animal’s motion, with stable EMG signal over several months. To decrease assembly time, reduce assembly errors, and improve repeatability, we fabricate assembly aids including a drive holder, a drill guide, an implant fixture for microelectode ‘pinning’, and a gold plating fixture. Significance. The

  1. Adding functionality with additive manufacturing: Fabrication of titanium-based antibiotic eluting implants.

    PubMed

    Cox, Sophie C; Jamshidi, Parastoo; Eisenstein, Neil M; Webber, Mark A; Hassanin, Hany; Attallah, Moataz M; Shepherd, Duncan E T; Addison, Owen; Grover, Liam M

    2016-07-01

    Additive manufacturing technologies have been utilised in healthcare to create patient-specific implants. This study demonstrates the potential to add new implant functionality by further exploiting the design flexibility of these technologies. Selective laser melting was used to manufacture titanium-based (Ti-6Al-4V) implants containing a reservoir. Pore channels, connecting the implant surface to the reservoir, were incorporated to facilitate antibiotic delivery. An injectable brushite, calcium phosphate cement, was formulated as a carrier vehicle for gentamicin. Incorporation of the antibiotic significantly (p=0.01) improved the compressive strength (5.8±0.7MPa) of the cement compared to non-antibiotic samples. The controlled release of gentamicin sulphate from the calcium phosphate cement injected into the implant reservoir was demonstrated in short term elution studies using ultraviolet-visible spectroscopy. Orientation of the implant pore channels were shown, using micro-computed tomography, to impact design reproducibility and the back-pressure generated during cement injection which ultimately altered porosity. The amount of antibiotic released from all implant designs over a 6hour period (<28% of the total amount) were found to exceed the minimum inhibitory concentrations of Staphylococcus aureus (16μg/mL) and Staphylococcus epidermidis (1μg/mL); two bacterial species commonly associated with periprosthetic infections. Antibacterial efficacy was confirmed against both bacterial cultures using an agar diffusion assay. Interestingly, pore channel orientation was shown to influence the directionality of inhibition zones. Promisingly, this work demonstrates the potential to additively manufacture a titanium-based antibiotic eluting implant, which is an attractive alternative to current treatment strategies of periprosthetic infections. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Analysis of electrically evoked compound action potential of the auditory nerve in children with bilateral cochlear implants.

    PubMed

    Caldas, Fernanda Ferreira; Cardoso, Carolina Costa; Barreto, Monique Antunes de Souza Chelminski; Teixeira, Marina Santos; Hilgenberg, Anacléia Melo da Silva; Serra, Lucieny Silva Martins; Bahmad Junior, Fayez

    2016-01-01

    The cochlear implant device has the capacity to measure the electrically evoked compound action potential of the auditory nerve. The neural response telemetry is used in order to measure the electrically evoked compound action potential of the auditory nerve. To analyze the electrically evoked compound action potential, through the neural response telemetry, in children with bilateral cochlear implants. This is an analytical, prospective, longitudinal, historical cohort study. Six children, aged 1-4 years, with bilateral cochlear implant were assessed at five different intervals during their first year of cochlear implant use. There were significant differences in follow-up time (p=0.0082) and electrode position (p=0.0019) in the T-NRT measure. There was a significant difference in the interaction between time of follow-up and electrode position (p=0.0143) when measuring the N1-P1 wave amplitude between the three electrodes at each time of follow-up. The electrically evoked compound action potential measurement using neural response telemetry in children with bilateral cochlear implants during the first year of follow-up was effective in demonstrating the synchronized bilateral development of the peripheral auditory pathways in the studied population. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  3. An Improved Cloud Classification Algorithm for China's FY-2C Multi-Channel Images Using Artificial Neural Network.

    PubMed

    Liu, Yu; Xia, Jun; Shi, Chun-Xiang; Hong, Yang

    2009-01-01

    The crowning objective of this research was to identify a better cloud classification method to upgrade the current window-based clustering algorithm used operationally for China's first operational geostationary meteorological satellite FengYun-2C (FY-2C) data. First, the capabilities of six widely-used Artificial Neural Network (ANN) methods are analyzed, together with the comparison of two other methods: Principal Component Analysis (PCA) and a Support Vector Machine (SVM), using 2864 cloud samples manually collected by meteorologists in June, July, and August in 2007 from three FY-2C channel (IR1, 10.3-11.3 μm; IR2, 11.5-12.5 μm and WV 6.3-7.6 μm) imagery. The result shows that: (1) ANN approaches, in general, outperformed the PCA and the SVM given sufficient training samples and (2) among the six ANN networks, higher cloud classification accuracy was obtained with the Self-Organizing Map (SOM) and Probabilistic Neural Network (PNN). Second, to compare the ANN methods to the present FY-2C operational algorithm, this study implemented SOM, one of the best ANN network identified from this study, as an automated cloud classification system for the FY-2C multi-channel data. It shows that SOM method has improved the results greatly not only in pixel-level accuracy but also in cloud patch-level classification by more accurately identifying cloud types such as cumulonimbus, cirrus and clouds in high latitude. Findings of this study suggest that the ANN-based classifiers, in particular the SOM, can be potentially used as an improved Automated Cloud Classification Algorithm to upgrade the current window-based clustering method for the FY-2C operational products.

  4. Multiple spectral channels in branchiopods. I. Vision in dim light and neural correlates.

    PubMed

    Lessios, Nicolas; Rutowski, Ronald L; Cohen, Jonathan H; Sayre, Marcel E; Strausfeld, Nicholas J

    2018-05-22

    Animals that have true color vision possess several spectral classes of photoreceptors. Pancrustaceans (Hexapoda+Crustacea) that integrate spectral information about their reconstructed visual world do so from photoreceptor terminals supplying their second optic neuropils, with subsequent participation of the third (lobula) and deeper centers (optic foci). Here, we describe experiments and correlative neural arrangements underlying convergent visual pathways in two species of branchiopod crustaceans that have to cope with a broad range of spectral ambience and illuminance in ephemeral pools, yet possess just two optic neuropils, the lamina and the optic tectum. Electroretinographic recordings and multimodel inference based on modeled spectral absorptance were used to identify the most likely number of spectral photoreceptor classes in their compound eyes. Recordings from the retina provide support for four color channels. Neuroanatomical observations resolve arrangements in their laminas that suggest signal summation at low light intensities, incorporating chromatic channels. Neuroanatomical observations demonstrate that spatial summation in the lamina of the two species are mediated by quite different mechanisms, both of which allow signals from several ommatidia to be pooled at single lamina monopolar cells. We propose that such summation provides sufficient signal for vision at intensities equivalent to those experienced by insects in terrestrial habitats under dim starlight. Our findings suggest that despite the absence of optic lobe neuropils necessary for spectral discrimination utilized by true color vision, four spectral photoreceptor classes have been maintained in Branchiopoda for vision at very low light intensities at variable ambient wavelengths that typify conditions in ephemeral freshwater habitats. © 2018. Published by The Company of Biologists Ltd.

  5. Factor-Analysis Methods for Higher-Performance Neural Prostheses

    PubMed Central

    Santhanam, Gopal; Yu, Byron M.; Gilja, Vikash; Ryu, Stephen I.; Afshar, Afsheen; Sahani, Maneesh; Shenoy, Krishna V.

    2009-01-01

    Neural prostheses aim to provide treatment options for individuals with nervous-system disease or injury. It is necessary, however, to increase the performance of such systems before they can be clinically viable for patients with motor dysfunction. One performance limitation is the presence of correlated trial-to-trial variability that can cause neural responses to wax and wane in concert as the subject is, for example, more attentive or more fatigued. If a system does not properly account for this variability, it may mistakenly interpret such variability as an entirely different intention by the subject. We report here the design and characterization of factor-analysis (FA)–based decoding algorithms that can contend with this confound. We characterize the decoders (classifiers) on experimental data where monkeys performed both a real reach task and a prosthetic cursor task while we recorded from 96 electrodes implanted in dorsal premotor cortex. The decoder attempts to infer the underlying factors that comodulate the neurons' responses and can use this information to substantially lower error rates (one of eight reach endpoint predictions) by ≲75% (e.g., ∼20% total prediction error using traditional independent Poisson models reduced to ∼5%). We also examine additional key aspects of these new algorithms: the effect of neural integration window length on performance, an extension of the algorithms to use Poisson statistics, and the effect of training set size on the decoding accuracy of test data. We found that FA-based methods are most effective for integration windows >150 ms, although still advantageous at shorter timescales, that Gaussian-based algorithms performed better than the analogous Poisson-based algorithms and that the FA algorithm is robust even with a limited amount of training data. We propose that FA-based methods are effective in modeling correlated trial-to-trial neural variability and can be used to substantially increase overall

  6. Close-field electroporation gene delivery using the cochlear implant electrode array enhances the bionic ear.

    PubMed

    Pinyon, Jeremy L; Tadros, Sherif F; Froud, Kristina E; Y Wong, Ann C; Tompson, Isabella T; Crawford, Edward N; Ko, Myungseo; Morris, Renée; Klugmann, Matthias; Housley, Gary D

    2014-04-23

    The cochlear implant is the most successful bionic prosthesis and has transformed the lives of people with profound hearing loss. However, the performance of the "bionic ear" is still largely constrained by the neural interface itself. Current spread inherent to broad monopolar stimulation of the spiral ganglion neuron somata obviates the intrinsic tonotopic mapping of the cochlear nerve. We show in the guinea pig that neurotrophin gene therapy integrated into the cochlear implant improves its performance by stimulating spiral ganglion neurite regeneration. We used the cochlear implant electrode array for novel "close-field" electroporation to transduce mesenchymal cells lining the cochlear perilymphatic canals with a naked complementary DNA gene construct driving expression of brain-derived neurotrophic factor (BDNF) and a green fluorescent protein (GFP) reporter. The focusing of electric fields by particular cochlear implant electrode configurations led to surprisingly efficient gene delivery to adjacent mesenchymal cells. The resulting BDNF expression stimulated regeneration of spiral ganglion neurites, which had atrophied 2 weeks after ototoxic treatment, in a bilateral sensorineural deafness model. In this model, delivery of a control GFP-only vector failed to restore neuron structure, with atrophied neurons indistinguishable from unimplanted cochleae. With BDNF therapy, the regenerated spiral ganglion neurites extended close to the cochlear implant electrodes, with localized ectopic branching. This neural remodeling enabled bipolar stimulation via the cochlear implant array, with low stimulus thresholds and expanded dynamic range of the cochlear nerve, determined via electrically evoked auditory brainstem responses. This development may broadly improve neural interfaces and extend molecular medicine applications.

  7. Comparison of Results of Measurement of Dimensions of the Placed Dental Implants on Cone Beam Computed Tomography with Dimensions of the Producers of the Implants.

    PubMed

    Repesa, Merisa; Sofic, Amela; Jakupovic, Selma; Tosum, Selma; Kazazic, Lejla; Dervisevic, Almir

    2017-06-01

    One of the most frequently used method for scanning patients with indication for dental implantation in dentistry is cone beam computed tomography. Implantation, CBCT imaging and implant programme are inevitable when planning a successful replacement of lost teeth. CBCT offers exact information about available bone and its density, adjacent tooth roots, the place of mandibular canal and maxillary sinus and adjacent anatomical structure. The goal of this study is to estimate accuracy of measurements on CBCT images ofpatients who have implants of different producers and determine if there is any statistically significant correlation between four test groups regardless of the alloy of which implants are made. The study was a prospective-comparative, and included fifteen patients with hundred dental implants divided in four groups depending on the producer. Over dimensioning in the gained measurements of the whole sample on CBCT images in relation to dimensions of producers is between 0.1006mm and 0.368mm. Even though over dimensioning is measured in millimetres, it has to be taken into consideration in clinical practice when planning an implant placement, and we can recommend safety zone of 0.5mm. There have been no statistically significant differences in the gained results in over dimensioning of implants of different alloys for horizontal and vertical measurements on CBCT images of Astra Tech, Brendet titanium implants and Straumann titanium-zirconium implants. Based on the goals of the study there have been confirmed statistically significant correlations of great value (from 0.841 to 0.936) of high level of importance between manufactured value of dimensions and average dimensions values gained through CBCT imaging in four types of implants (four test groups). The total exactness of measurements on CBCT scan in this research is 96.66% for horizontal measuring and 96.92% for vertical measuring. Therefore, we can conclude that CBCT as radiological method has an

  8. Visualization of cortical, subcortical, and deep brain neural circuit dynamics during naturalistic mammalian behavior with head-mounted microscopes and chronically implanted lenses

    PubMed Central

    Resendez, Shanna L.; Jennings, Josh H.; Ung, Randall L.; Namboodiri, Vijay Mohan K.; Zhou, Zhe Charles; Otis, James M.; Nomura, Hiroshi; McHenry, Jenna A.; Kosyk, Oksana; Stuber, Garret D.

    2016-01-01

    Genetically encoded calcium indicators for visualizing dynamic cellular activity have greatly expanded our understanding of the brain. However, due to light scattering properties of the brain as well as the size and rigidity of traditional imaging technology, in vivo calcium imaging has been limited to superficial brain structures during head fixed behavioral tasks. This limitation can now be circumvented by utilizing miniature, integrated microscopes in conjunction with an implantable microendoscopic lens to guide light into and out of the brain, thus permitting optical access to deep brain (or superficial) neural ensembles during naturalistic behaviors. Here, we describe procedural steps to conduct such imaging studies using mice. However, we anticipate the protocol can be easily adapted for use in other small vertebrates. Successful completion of this protocol will permit cellular imaging of neuronal activity and the generation of data sets with sufficient statistical power to correlate neural activity with stimulus presentation, physiological state, and other aspects of complex behavioral tasks. This protocol takes 6–11 weeks to complete. PMID:26914316

  9. Fully Integrated Silicon Probes for High-Density Recording of Neural Activity

    PubMed Central

    Jun, James J.; Steinmetz, Nicholas A.; Siegle, Joshua H.; Denman, Daniel J.; Bauza, Marius; Barbarits, Brian; Lee, Albert K.; Anastassiou, Costas A.; Andrei, Alexandru; Aydın, Çağatay; Barbic, Mladen; Blanche, Timothy J.; Bonin, Vincent; Couto, João; Dutta, Barundeb; Gratiy, Sergey L.; Gutnisky, Diego A.; Häusser, Michael; Karsh, Bill; Ledochowitsch, Peter; Lopez, Carolina Mora; Mitelut, Catalin; Musa, Silke; Okun, Michael; Pachitariu, Marius; Putzeys, Jan; Rich, P. Dylan; Rossant, Cyrille; Sun, Wei-lung; Svoboda, Karel; Carandini, Matteo; Harris, Kenneth D.; Koch, Christof; O'Keefe, John; Harris, Timothy D.

    2018-01-01

    Summary Paragraph Sensory, motor, and cognitive operations involve the coordinated action of large neuronal populations across multiple brain regions in both superficial and deep structures1,2. Existing extracellular probes record neural activity with excellent spatial and temporal (sub-millisecond) resolution but from only a few dozen neurons per shank. Optical Ca2+ imaging3–5 offers more coverage but lacks the temporal resolution to reliably distinguish individual spikes and does not measure local field potentials. To date, no technology compatible with unrestrained animals has combined high spatiotemporal resolution with large volume coverage. To satisfy this need, we designed, fabricated, and tested a new silicon probe called Neuropixels. Each probe has 384 recording channels that can programmably address 960 CMOS processing-compatible low-impedance TiN6 sites that tile a single 10 mm long, 70x20 µm cross section shank. The 6x9 mm probe base is fabricated with the shank on a single chip. Voltage signals are filtered, amplified, multiplexed, and digitized on the base, allowing noise-free digital data transmission directly from the probe. The combination of dense recording sites and high channel count yielded well-isolated spiking activity from hundreds of neurons per probe implanted in mice and rats. Using two probes, more than 700 well-isolated single neurons were simultaneously recorded from five brain structures in an awake mouse. The fully integrated functionality and small size of Neuropixels probes allowed recording large populations of neurons from multiple brain structures in freely moving animals. This combination of high-performance electrode technology and scalable chip fabrication methods opens the path to record brain-wide neural activity during behavior. PMID:29120427

  10. Short dental implants versus standard dental implants placed in the posterior jaws: A systematic review and meta-analysis.

    PubMed

    Lemos, Cleidiel Aparecido Araujo; Ferro-Alves, Marcio Luiz; Okamoto, Roberta; Mendonça, Marcos Rogério; Pellizzer, Eduardo Piza

    2016-04-01

    The purpose of the present systematic review and meta-analysis was to compare short implants (equal or less than 8mm) versus standard implants (larger than 8mm) placed in posterior regions of maxilla and mandible, evaluating survival rates of implants, marginal bone loss, complications and prosthesis failures. This review has been registered at PROSPERO under the number CRD42015016588. Main search terms were used in combination: dental implant, short implant, short dental implants, short dental implants posterior, short dental implants maxilla, and short dental implants mandible. An electronic search for data published up until September/2015 was undertaken using the PubMed/Medline, Embase and The Cochrane Library databases. Eligibility criteria included clinical human studies, randomized controlled trials and/or prospective studies, which evaluated short implants in comparison to standard implants in the same study. The search identified 1460 references, after inclusion criteria 13 studies were assessed for eligibility. A total of 1269 patients, who had received a total of 2631 dental implants. The results showed that there was no significant difference of implants survival (P=.24; RR:1.35; CI: 0.82-2.22), marginal bone loss (P=.06; MD: -0.20; CI: -0.41 to 0.00), complications (P=.08; RR:0.54; CI: 0.27-1.09) and prosthesis failures (P=.92; RR:0.96; CI: 0.44-2.09). Short implants are considered a predictable treatment for posterior jaws. However, short implants with length less than 8 mm (4-7 mm) should be used with caution because they present greater risks to failures compared to standard implants. Short implants are frequently placed in the posterior area in order to avoid complementary surgical procedures. However, clinicians need to be aware that short implants with length less than 8mm present greater risk of failures. Copyright © 2016. Published by Elsevier Ltd.

  11. Modulation of Kv7 channels and excitability in the brain.

    PubMed

    Greene, Derek L; Hoshi, Naoto

    2017-02-01

    Neuronal Kv7 channels underlie a voltage-gated non-inactivating potassium current known as the M-current. Due to its particular characteristics, Kv7 channels show pronounced control over the excitability of neurons. We will discuss various factors that have been shown to drastically alter the activity of this channel such as protein and phospholipid interactions, phosphorylation, calcium, and numerous neurotransmitters. Kv7 channels locate to key areas for the control of action potential initiation and propagation. Moreover, we will explore the dynamic surface expression of the channel modulated by neurotransmitters and neural activity. We will also focus on known principle functions of neural Kv7 channels: control of resting membrane potential and spiking threshold, setting the firing frequency, afterhyperpolarization after burst firing, theta resonance, and transient hyperexcitability from neurotransmitter-induced suppression of the M-current. Finally, we will discuss the contribution of altered Kv7 activity to pathologies such as epilepsy and cognitive deficits.

  12. Modulation of Kv7 channels and excitability in the brain

    PubMed Central

    Greene, Derek L; Hoshi, Naoto

    2016-01-01

    Neuronal Kv7 channels underlie a voltage-gated non-inactivating potassium current known as the M-current. Due to its particular characteristics, Kv7 channels show pronounced control over the excitability of neurons. We will discuss various factors that have been shown to drastically alter the activity of this channel such as protein and phospholipid interactions, phosphorylation, calcium, and numerous neurotransmitters. Kv7 channels locate to key areas for the control of action potential initiation and propagation. Moreover, we will explore the dynamic surface expression of the channel modulated by neurotransmitters and neural activity. We will also focus on known principle functions of neural Kv7 channels: control of resting membrane potential and spiking threshold, setting the firing frequency, afterhyperpolarization after burst firing, theta resonance, and transient hyperexcitability from neurotransmitter-induced suppression of the M-current. Finally, we will discuss the contribution of altered Kv7 activity to pathologies such as epilepsy and cognitive deficits. PMID:27645822

  13. Implantable radio frequency identification sensors: wireless power and communication.

    PubMed

    Hutchens, Chriswell; Rennaker, Robert L; Venkataraman, Srinivasan; Ahmed, Rehan; Liao, Ran; Ibrahim, Tamer

    2011-01-01

    There are significant technical challenges in the development of a fully implantable wirelessly powered neural interface. Challenges include wireless transmission of sufficient power to the implanted device to ensure reliable operation for decades without replacement, minimizing tissue heating, and adequate reliable communications bandwidth. Overcoming these challenges is essential for the development of implantable closed loop system for the treatment of disorders ranging from epilepsy, incontinence, stroke and spinal cord injury. We discuss the development of the wireless power, communication and control for a Radio-Frequency Identification Sensor (RFIDS) system with targeted power range for a 700 mV, 30 to 40 uA load attained at -2 dBm.

  14. Wireless multi-channel single unit recording in freely moving and vocalizing primates

    PubMed Central

    Roy, Sabyasachi; Wang, Xiaoqin

    2011-01-01

    The ability to record well-isolated action potentials from individual neurons in naturally behaving animals is crucial for understanding neural mechanisms underlying natural behaviors. Traditional neurophysiology techniques, however, require the animal to be restrained which often restricts natural behavior. An example is the common marmoset (Callithrix jacchus), a highly vocal New World primate species, used in our laboratory to study the neural correlates of vocal production and sensory feedback. When restrained by traditional neurophysiological techniques marmoset vocal behavior is severely inhibited. Tethered recording systems, while proven effective in rodents pose limitations in arboreal animals such as the marmoset that typically roam in a three-dimensional environment. To overcome these obstacles, we have developed a wireless neural recording technique that is capable of collecting single-unit data from chronically implanted multi-electrodes in freely moving marmosets. A lightweight, low power and low noise wireless transmitter (headstage) is attached to a multi-electrode array placed in the premotor cortex of the marmoset. The wireless headstage is capable of transmitting 15 channels of neural data with signal-to-noise ratio (SNR) comparable to a tethered system. To minimize radio-frequency (RF) and electro-magnetic interference (EMI), the experiments were conducted within a custom designed RF/EMI and acoustically shielded chamber. The individual electrodes of the multi-electrode array were periodically advanced to densely sample the cortical layers. We recorded single-unit data over a period of several months from the frontal cortex of two marmosets. These recordings demonstrate the feasibility of using our wireless recording method to study single neuron activity in freely roaming primates. PMID:21933683

  15. A fast button surface defects detection method based on convolutional neural network

    NASA Astrophysics Data System (ADS)

    Liu, Lizhe; Cao, Danhua; Wu, Songlin; Wu, Yubin; Wei, Taoran

    2018-01-01

    Considering the complexity of the button surface texture and the variety of buttons and defects, we propose a fast visual method for button surface defect detection, based on convolutional neural network (CNN). CNN has the ability to extract the essential features by training, avoiding designing complex feature operators adapted to different kinds of buttons, textures and defects. Firstly, we obtain the normalized button region and then use HOG-SVM method to identify the front and back side of the button. Finally, a convolutional neural network is developed to recognize the defects. Aiming at detecting the subtle defects, we propose a network structure with multiple feature channels input. To deal with the defects of different scales, we take a strategy of multi-scale image block detection. The experimental results show that our method is valid for a variety of buttons and able to recognize all kinds of defects that have occurred, including dent, crack, stain, hole, wrong paint and uneven. The detection rate exceeds 96%, which is much better than traditional methods based on SVM and methods based on template match. Our method can reach the speed of 5 fps on DSP based smart camera with 600 MHz frequency.

  16. Selective Manipulation of Neural Circuits.

    PubMed

    Park, Hong Geun; Carmel, Jason B

    2016-04-01

    Unraveling the complex network of neural circuits that form the nervous system demands tools that can manipulate specific circuits. The recent evolution of genetic tools to target neural circuits allows an unprecedented precision in elucidating their function. Here we describe two general approaches for achieving circuit specificity. The first uses the genetic identity of a cell, such as a transcription factor unique to a circuit, to drive expression of a molecule that can manipulate cell function. The second uses the spatial connectivity of a circuit to achieve specificity: one genetic element is introduced at the origin of a circuit and the other at its termination. When the two genetic elements combine within a neuron, they can alter its function. These two general approaches can be combined to allow manipulation of neurons with a specific genetic identity by introducing a regulatory gene into the origin or termination of the circuit. We consider the advantages and disadvantages of both these general approaches with regard to specificity and efficacy of the manipulations. We also review the genetic techniques that allow gain- and loss-of-function within specific neural circuits. These approaches introduce light-sensitive channels (optogenetic) or drug sensitive channels (chemogenetic) into neurons that form specific circuits. We compare these tools with others developed for circuit-specific manipulation and describe the advantages of each. Finally, we discuss how these tools might be applied for identification of the neural circuits that mediate behavior and for repair of neural connections.

  17. Auditory cortical activity during cochlear implant-mediated perception of spoken language, melody, and rhythm.

    PubMed

    Limb, Charles J; Molloy, Anne T; Jiradejvong, Patpong; Braun, Allen R

    2010-03-01

    Despite the significant advances in language perception for cochlear implant (CI) recipients, music perception continues to be a major challenge for implant-mediated listening. Our understanding of the neural mechanisms that underlie successful implant listening remains limited. To our knowledge, this study represents the first neuroimaging investigation of music perception in CI users, with the hypothesis that CI subjects would demonstrate greater auditory cortical activation than normal hearing controls. H(2) (15)O positron emission tomography (PET) was used here to assess auditory cortical activation patterns in ten postlingually deafened CI patients and ten normal hearing control subjects. Subjects were presented with language, melody, and rhythm tasks during scanning. Our results show significant auditory cortical activation in implant subjects in comparison to control subjects for language, melody, and rhythm. The greatest activity in CI users compared to controls was seen for language tasks, which is thought to reflect both implant and neural specializations for language processing. For musical stimuli, PET scanning revealed significantly greater activation during rhythm perception in CI subjects (compared to control subjects), and the least activation during melody perception, which was the most difficult task for CI users. These results may suggest a possible relationship between auditory performance and degree of auditory cortical activation in implant recipients that deserves further study.

  18. Relevant Anatomy, Morphology, and Implantation Techniques of the Dorsal Root Ganglia at the Lumbar Levels.

    PubMed

    Vancamp, Tim; Levy, Robert M; Peña, Isaac; Pajuelo, Antonio

    2017-10-01

    While dorsal root ganglion (DRG) stimulation has been available in Europe and Australia for the past five years and in the United States for the past year, there are no published details concerning the optimal procedures for DRG lead implantation. We describe several techniques that can be applied to implant cylindrical leads over the DRG, highlighting some tips and tricks according to our experiences. Focus is mainly shifted toward implantations in the lumbar area. We furthermore give some insights in the results we experienced in Spain as well as some worldwide numbers. A 14-gauge needle is placed using a "2-Level Technique (2-LT)" or exceptionally a "1-Level Technique (1-LT)" or a "Primary- or Secondary Technique" at the level of L5. The delivery sheath, loaded with the lead, is advanced toward the targeted neural foramen. The lead is placed over the dorsal aspect of the DRG. A strain relief loop is created in the epidural space. Sheath and needle are retracted and the lead is secured using an anchor or anchorless technique. In Spain, 87.2% (N = 78) of the selected patients have been successfully implanted. Seven (8.9%) had a negative trial and three (4.2%) were explanted. Average VAS score decreased from 8.8 to 3.3 and on average 94.5% of the pain area was covered. In our center's subjects (N = 47 patients, 60.3% of all implanted patients in Spain), VAS scores decreased from an average of 8.8-1.7 and pain coverage averaged 96.4%. We used an average of 1.8 electrodes. Worldwide more than 4000 permanent cases have been successfully performed. We present implantation techniques whereby a percutaneous lead is placed over the DRG through the use of a special designed delivery sheath. Further investigation of the safety, efficacy, and sustainability of clinical outcomes using these devices is warranted. © 2017 International Neuromodulation Society.

  19. 3D-nanostructured boron-doped diamond for microelectrode array neural interfacing.

    PubMed

    Piret, Gaëlle; Hébert, Clément; Mazellier, Jean-Paul; Rousseau, Lionel; Scorsone, Emmanuel; Cottance, Myline; Lissorgues, Gaelle; Heuschkel, Marc O; Picaud, Serge; Bergonzo, Philippe; Yvert, Blaise

    2015-06-01

    The electrode material is a key element in the design of long-term neural implants and neuroprostheses. To date, the ideal electrode material offering high longevity, biocompatibility, low-noise recording and high stimulation capabilities remains to be found. We show that 3D-nanostructured boron doped diamond (BDD), an innovative material consisting in a chemically stable material with a high aspect ratio structure obtained by encapsulation of a carbon nanotube template within two BDD nanolayers, allows neural cell attachment, survival and neurite extension. Further, we developed arrays of 20-μm-diameter 3D-nanostructured BDD microelectrodes for neural interfacing. These microelectrodes exhibited low impedances and low intrinsic recording noise levels. In particular, they allowed the detection of low amplitude (10-20 μV) local-field potentials, single units and multiunit bursts neural activity in both acute whole embryonic hindbrain-spinal cord preparations and long-term hippocampal cell cultures. Also, cyclic voltammetry measurements showed a wide potential window of about 3 V and a charge storage capacity of 10 mC.cm(-2), showing high potentiality of this material for neural stimulation. These results demonstrate the attractiveness of 3D-nanostructured BDD as a novel material for neural interfacing, with potential applications for the design of biocompatible neural implants for the exploration and rehabilitation of the nervous system. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  20. Dynamics of neural cryptography

    NASA Astrophysics Data System (ADS)

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  1. Dynamics of neural cryptography.

    PubMed

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  2. Integration of active devices on smart polymers for neural interfaces

    NASA Astrophysics Data System (ADS)

    Avendano-Bolivar, Adrian Emmanuel

    The increasing ability to ever more precisely identify and measure neural interactions and other phenomena in the central and peripheral nervous systems is revolutionizing our understanding of the human body and brain. To facilitate further understanding, more sophisticated neural devices, perhaps using microelectronics processing, must be fabricated. Materials often used in these neural interfaces, while compatible with these fabrication processes, are not optimized for long-term use in the body and are often orders of magnitude stiffer than the tissue with which they interact. Using the smart polymer substrates described in this work, suitability for processing as well as chronic implantation is demonstrated. We explore how to integrate reliable circuitry onto these flexible, biocompatible substrates that can withstand the aggressive environment of the body. To increase the capabilities of these devices beyond individual channel sensing and stimulation, active electronics must also be included onto our systems. In order to add this functionality to these substrates and explore the limits of these devices, we developed a process to fabricate single organic thin film transistors with mobilities up to 0.4 cm2/Vs and threshold voltages close to 0V. A process for fabricating organic light emitting diodes on flexible substrates is also addressed. We have set a foundation and demonstrated initial feasibility for integrating multiple transistors onto thin-film flexible devices to create new applications, such as matrix addressable functionalized electrodes and organic light emitting diodes. A brief description on how to integrate waveguides for their use in optogenetics is addressed. We have built understanding about device constraints on mechanical, electrical and in vivo reliability and how various conditions affect the electronics' lifetime. We use a bi-layer gate dielectric using an inorganic material such as HfO 2 combined with organic Parylene-c. A study of

  3. Cooperative Microsystems and Neural Interfaces

    DTIC Science & Technology

    2009-03-04

    polyimide coil for wireless power/data transfer F. Solzbacher, University of Utah – K. Shenoy, Stanford • Demonstrated wireless operation of implanted...Approach: Collapse cable into a single biocompatible optical fiber. Challenge: develop and demonstrate low power multi-channel data acquisition chip

  4. Comparative Study of MIL-96(Al) as Continuous Metal-Organic Frameworks Layer and Mixed-Matrix Membrane.

    PubMed

    Knebel, Alexander; Friebe, Sebastian; Bigall, Nadja Carola; Benzaqui, Marvin; Serre, Christian; Caro, Jürgen

    2016-03-23

    MIL-96(Al) layers were prepared as supported metal-organic frameworks membrane via reactive seeding using the α-alumina support as the Al source for the formation of the MIL-96(Al) seeds. Depending on the solvent mixture employed during seed formation, two different crystal morphologies, with different orientation of the transport-active channels, have been formed. This crystal orientation and habit is predefined by the seed crystals and is kept in the subsequent growth of the seeds to continuous layers. In the gas separation of an equimolar H2/CO2 mixture, the hydrogen permeability of the two supported MIL-96(Al) layers was found to be highly dependent on the crystal morphology and the accompanied channel orientation in the layer. In addition to the neat supported MIL-96(Al) membrane layers, mixed-matrix membranes (MMMs, 10 wt % filler loading) as a composite of MIL-96(Al) particles as filler in a continuous Matrimid polymer phase have been prepared. Five particle sizes of MIL-96(Al) between 3.2 μm and 55 nm were synthesized. In the preparation of the MIL-96(Al)/Matrimid MMM (10 wt % filler loading), the following preparation problems have been identified: The bigger micrometer-sized MIL-96(Al) crystals show a trend toward sedimentation during casting of the MMM, whereas for nanoparticles aggregation and recrystallization to micrometer-sized MIL-96(Al) crystals has been observed. Because of these preparation problems for MMM, the neat supported MIL-96(Al) layers show a relatively high H2/CO2 selectivity (≈9) and a hydrogen permeance approximately 2 magnitudes higher than that of the best MMM.

  5. In vivo characterization of the electrophysiological and astrocytic responses to a silicon neuroprobe implanted in the mouse neocortex.

    PubMed

    Mols, Katrien; Musa, Silke; Nuttin, Bart; Lagae, Liesbet; Bonin, Vincent

    2017-11-15

    Silicon neuroprobes hold great potential for studies of large-scale neural activity and brain computer interfaces, but data on brain response in chronic implants is limited. Here we explored with in vivo cellular imaging the response to multisite silicon probes for neural recordings. We tested a chronic implant for mice consisting of a CMOS-compatible silicon probe rigidly implanted in the cortex under a cranial imaging window. Multiunit recordings of cortical neurons with the implant showed no degradation of electrophysiological signals weeks after implantation (mean spike and noise amplitudes of 186 ± 42 µV pp and 16 ± 3.2 µV rms , respectively, n = 5 mice). Two-photon imaging through the cranial window allowed longitudinal monitoring of fluorescently-labeled astrocytes from the second week post implantation for 8 weeks (n = 3 mice). The imaging showed a local increase in astrocyte-related fluorescence that remained stable from the second to the tenth week post implantation. These results demonstrate that, in a standard electrophysiology protocol in mice, rigidly implanted silicon probes can provide good short to medium term chronic recording performance with a limited astrocyte inflammatory response. The precise factors influencing the response to silicon probe implants remain to be elucidated.

  6. Evaluating cochlear implant trauma to the scala vestibuli.

    PubMed

    Adunka, O; Kiefer, J; Unkelbach, M H; Radeloff, A; Gstoettner, W

    2005-04-01

    Placement of cochlear implant electrodes into the scala vestibuli may be intentional, e.g. in case of blocked scala tympani or unintentional as a result of trauma to the basilar membrane or erroneous location of the cochieostomy. The aim of this study was to evaluate the morphological consequences and cochlear trauma after implantation of different cochlear implant electrode arrays in the scala vestibuli. Human temporal bone study with histological and radiological evaluation. Twelve human cadaver temporal bones were implanted with different cochlear implant electrodes. Implanted bones were processed using a special method to section undecalcified bone. Cochlear trauma and intracochlear positions. All implanted electrodes were implanted into the scala vestibuli using a special approach that allows direct scala vestibuli insertions. Fractures of the osseous spiral lamina were evaluated in some bones in the basal cochlear regions. In most electrodes, delicate structures of the organ of Corti were left intact, however, Reissner's membrane was destroyed in all specimens and the electrode lay upon the tectorial membrane. In some bones the organ of Corti was destroyed. Scala vestibuli insertions did not cause severe trauma to osseous or neural structures, thus preserving the basis for electrostimulation of the cochlea. However, destruction of Reissner's membrane and impact on the Organ of Corti can be assumed to destroy residual hearing.

  7. Data fusion with artificial neural networks (ANN) for classification of earth surface from microwave satellite measurements

    NASA Technical Reports Server (NTRS)

    Lure, Y. M. Fleming; Grody, Norman C.; Chiou, Y. S. Peter; Yeh, H. Y. Michael

    1993-01-01

    A data fusion system with artificial neural networks (ANN) is used for fast and accurate classification of five earth surface conditions and surface changes, based on seven SSMI multichannel microwave satellite measurements. The measurements include brightness temperatures at 19, 22, 37, and 85 GHz at both H and V polarizations (only V at 22 GHz). The seven channel measurements are processed through a convolution computation such that all measurements are located at same grid. Five surface classes including non-scattering surface, precipitation over land, over ocean, snow, and desert are identified from ground-truth observations. The system processes sensory data in three consecutive phases: (1) pre-processing to extract feature vectors and enhance separability among detected classes; (2) preliminary classification of Earth surface patterns using two separate and parallely acting classifiers: back-propagation neural network and binary decision tree classifiers; and (3) data fusion of results from preliminary classifiers to obtain the optimal performance in overall classification. Both the binary decision tree classifier and the fusion processing centers are implemented by neural network architectures. The fusion system configuration is a hierarchical neural network architecture, in which each functional neural net will handle different processing phases in a pipelined fashion. There is a total of around 13,500 samples for this analysis, of which 4 percent are used as the training set and 96 percent as the testing set. After training, this classification system is able to bring up the detection accuracy to 94 percent compared with 88 percent for back-propagation artificial neural networks and 80 percent for binary decision tree classifiers. The neural network data fusion classification is currently under progress to be integrated in an image processing system at NOAA and to be implemented in a prototype of a massively parallel and dynamically reconfigurable Modular

  8. Evaluation of mandibular posterior single implants with two different surfaces: a 5-year comparative study.

    PubMed

    Jung, Ui-Won; Choi, Jung-Yoo; Kim, Chang-Sung; Cho, Kyoo-Sung; Chai, Jung-Kiu; Kim, Chong-Kwan; Choi, Seong-Ho

    2008-10-01

    Anatomic and biomechanical limitations can jeopardize successful single implantation in the mandibular posterior area. To overcome the limitations, the design and the surface of the fixtures were modified. This study evaluated the cumulative survival rate (CSR) of mandibular molars replaced with a sand-blasted, large-grit, acid-etched (SLA) single implant or an anodized (ANO) single implant and examined associated factors, such as the surface treatment, position, and length and diameter of the implants. One hundred ninety-three single implants restored with an SLA implant and 112 single implants restored with an ANO implant in the mandibular molar area were selected from subjects who had visited the Department of Periodontology, Dental Hospital of Yonsei University, from March 2001 through June 2006. In the SLA group, 123 and 70 implants were placed in the first and second molar area, respectively. In the ANO group, 55 and 57 implants were placed in the first and second molar area, respectively. The 1- to 6-year CSR of the SLA and ANO groups was calculated using the life-table analysis. In addition, associated factors, such as the surface treatment, position, and length and diameter of the implants, were compared and analyzed using the chi(2) test (P <0.05). Two of 193 implants in the SLA group failed, giving a CSR of 98.96%; four of 112 ANO implants failed, giving a CSR of 96.43%. There were no significant differences with regard to the surface treatment, position, and length and diameter of the implants. Despite the anatomic and biomechanical limitation in the mandibular posterior area, mandibular posterior single implants showed a high CSR during the observation period. Mandibular posterior single implants can be an effective and reliable treatment modality that is not affected by the surface treatment, position, or length and diameter of the implant.

  9. An Improved Cloud Classification Algorithm for China’s FY-2C Multi-Channel Images Using Artificial Neural Network

    PubMed Central

    Liu, Yu; Xia, Jun; Shi, Chun-Xiang; Hong, Yang

    2009-01-01

    The crowning objective of this research was to identify a better cloud classification method to upgrade the current window-based clustering algorithm used operationally for China’s first operational geostationary meteorological satellite FengYun-2C (FY-2C) data. First, the capabilities of six widely-used Artificial Neural Network (ANN) methods are analyzed, together with the comparison of two other methods: Principal Component Analysis (PCA) and a Support Vector Machine (SVM), using 2864 cloud samples manually collected by meteorologists in June, July, and August in 2007 from three FY-2C channel (IR1, 10.3–11.3 μm; IR2, 11.5–12.5 μm and WV 6.3–7.6 μm) imagery. The result shows that: (1) ANN approaches, in general, outperformed the PCA and the SVM given sufficient training samples and (2) among the six ANN networks, higher cloud classification accuracy was obtained with the Self-Organizing Map (SOM) and Probabilistic Neural Network (PNN). Second, to compare the ANN methods to the present FY-2C operational algorithm, this study implemented SOM, one of the best ANN network identified from this study, as an automated cloud classification system for the FY-2C multi-channel data. It shows that SOM method has improved the results greatly not only in pixel-level accuracy but also in cloud patch-level classification by more accurately identifying cloud types such as cumulonimbus, cirrus and clouds in high latitude. Findings of this study suggest that the ANN-based classifiers, in particular the SOM, can be potentially used as an improved Automated Cloud Classification Algorithm to upgrade the current window-based clustering method for the FY-2C operational products. PMID:22346714

  10. Neural prostheses in clinical applications--trends from precision mechanics towards biomedical microsystems in neurological rehabilitation.

    PubMed

    Stieglitz, T; Schuettler, M; Koch, K P

    2004-04-01

    Neural prostheses partially restore body functions by technical nerve excitation after trauma or neurological diseases. External devices and implants have been developed since the early 1960s for many applications. Several systems have reached nowadays clinical practice: Cochlea implants help the deaf to hear, micturition is induced by bladder stimulators in paralyzed persons and deep brain stimulation helps patients with Parkinson's disease to participate in daily life again. So far, clinical neural prostheses are fabricated with means of precision mechanics. Since microsystem technology opens the opportunity to design and develop complex systems with a high number of electrodes to interface with the nervous systems, the opportunity for selective stimulation and complex implant scenarios seems to be feasible in the near future. The potentials and limitations with regard to biomedical microdevices are introduced and discussed in this paper. Target specifications are derived from existing implants and are discussed on selected applications that has been investigated in experimental research: a micromachined implant to interface a nerve stump with a sieve electrode, cuff electrodes with integrated electronics, and an epiretinal vision prosthesis.

  11. Nanoscale laminin coating modulates cortical scarring response around implanted silicon microelectrode arrays

    NASA Astrophysics Data System (ADS)

    He, Wei; McConnell, George C.; Bellamkonda, Ravi V.

    2006-12-01

    Neural electrodes could significantly enhance the quality of life for patients with sensory and/or motor deficits as well as improve our understanding of brain functions. However, long-term electrical connectivity between neural tissue and recording sites is compromised by the development of astroglial scar around the recording probes. In this study we investigate the effect of a nanoscale laminin (LN) coating on Si-based neural probes on chronic cortical tissue reaction in a rat model. Tissue reaction was evaluated after 1 day, 1 week, and 4 weeks post-implant for coated and uncoated probes using immunohistochemical techniques to evaluate activated microglia/macrophages (ED-1), astrocytes (GFAP) and neurons (NeuN). The coating did not have an observable effect on neuronal density or proximity to the electrode surface. However, the response of microglia/macrophages and astrocytes was altered by the coating. One day post-implant, we observed an ~60% increase in ED-1 expression near LN-coated probe sites compared with control uncoated probe sites. Four weeks post-implant, we observed an ~20% reduction in ED-1 expression along with an ~50% reduction in GFAP expression at coated relative to uncoated probe sites. These results suggest that LN has a stimulatory effect on early microglia activation, accelerating the phagocytic function of these cells. This hypothesis is further supported by the increased mRNA expression of several pro-inflammatory cytokines (TNF-α, IL-1 and IL-6) in cultured microglia on LN-bound Si substrates. LN immunostaining of coated probes immediately after insertion and retrieval demonstrates that the coating integrity is not compromised by the shear force during insertion. We speculate, based on these encouraging results, that LN coating of Si neural probes could potentially improve chronic neural recordings through dispersion of the astroglial scar.

  12. Implantable neurotechnologies: bidirectional neural interfaces--applications and VLSI circuit implementations.

    PubMed

    Greenwald, Elliot; Masters, Matthew R; Thakor, Nitish V

    2016-01-01

    A bidirectional neural interface is a device that transfers information into and out of the nervous system. This class of devices has potential to improve treatment and therapy in several patient populations. Progress in very large-scale integration has advanced the design of complex integrated circuits. System-on-chip devices are capable of recording neural electrical activity and altering natural activity with electrical stimulation. Often, these devices include wireless powering and telemetry functions. This review presents the state of the art of bidirectional circuits as applied to neuroprosthetic, neurorepair, and neurotherapeutic systems.

  13. Kv1 channels and neural processing in vestibular calyx afferents.

    PubMed

    Meredith, Frances L; Kirk, Matthew E; Rennie, Katherine J

    2015-01-01

    Potassium-selective ion channels are important for accurate transmission of signals from auditory and vestibular sensory end organs to their targets in the central nervous system. During different gravity conditions, astronauts experience altered input signals from the peripheral vestibular system resulting in sensorimotor dysfunction. Adaptation to altered sensory input occurs, but it is not explicitly known whether this involves synaptic modifications within the vestibular epithelia. Future investigations of such potential plasticity require a better understanding of the electrophysiological mechanisms underlying the known heterogeneity of afferent discharge under normal conditions. This study advances this understanding by examining the role of the Kv1 potassium channel family in mediating action potentials in specialized vestibular afferent calyx endings in the gerbil crista and utricle. Pharmacological agents selective for different sub-types of Kv1 channels were tested on membrane responses in whole cell recordings in the crista. Kv1 channels sensitive to α-dendrotoxin and dendrotoxin-K were found to prevail in the central regions, whereas K(+) channels sensitive to margatoxin, which blocks Kv1.3 and 1.6 channels, were more prominent in peripheral regions. Margatoxin-sensitive currents showed voltage-dependent inactivation. Dendrotoxin-sensitive currents showed no inactivation and dampened excitability in calyces in central neuroepithelial regions. The differential distribution of Kv1 potassium channels in vestibular afferents supports their importance in accurately relaying gravitational and head movement signals through specialized lines to the central nervous system. Pharmacological modulation of specific groups of K(+) channels could help alleviate vestibular dysfunction on earth and in space.

  14. Neural Parallel Engine: A toolbox for massively parallel neural signal processing.

    PubMed

    Tam, Wing-Kin; Yang, Zhi

    2018-05-01

    Large-scale neural recordings provide detailed information on neuronal activities and can help elicit the underlying neural mechanisms of the brain. However, the computational burden is also formidable when we try to process the huge data stream generated by such recordings. In this study, we report the development of Neural Parallel Engine (NPE), a toolbox for massively parallel neural signal processing on graphical processing units (GPUs). It offers a selection of the most commonly used routines in neural signal processing such as spike detection and spike sorting, including advanced algorithms such as exponential-component-power-component (EC-PC) spike detection and binary pursuit spike sorting. We also propose a new method for detecting peaks in parallel through a parallel compact operation. Our toolbox is able to offer a 5× to 110× speedup compared with its CPU counterparts depending on the algorithms. A user-friendly MATLAB interface is provided to allow easy integration of the toolbox into existing workflows. Previous efforts on GPU neural signal processing only focus on a few rudimentary algorithms, are not well-optimized and often do not provide a user-friendly programming interface to fit into existing workflows. There is a strong need for a comprehensive toolbox for massively parallel neural signal processing. A new toolbox for massively parallel neural signal processing has been created. It can offer significant speedup in processing signals from large-scale recordings up to thousands of channels. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Post-traumatic implant-supported restoration of the anterior maxillary teeth using cancellous bone block allografts.

    PubMed

    Nissan, Joseph; Gross, Ora; Mardinger, Ofer; Ghelfan, Oded; Sacco, Roberto; Chaushu, Gavriel

    2011-12-01

    To prospectively evaluate the outcome of dental implants placed in the post-traumatic anterior maxilla after ridge augmentation with cancellous freeze-dried block bone allografts. Patients presenting with a history of anterior dentoalveolar trauma with bony deficiencies in the sagittal (≥3 mm) and vertical (<3 mm) planes according to computed tomography were included. The recipient sites were reconstructed with cancellous bone block allografts. After 6 months of healing, implants were placed. The primary outcomes of interest were 1) bone measurements taken before grafting, at the time of implant placement, and at stage 2 operations; 2) implant survival; and 3) complications. The sample was composed of 20 consecutive patients with a mean age of 25 ± 7 years. We used 28 cancellous allogeneic bone blocks, and 31 implants were inserted. Of the 31 implants, 12 were immediately restored. The mean follow-up was 42 ± 15 months. Graft and implant survival rates were 92.8% and 96.8%, respectively. Mean bone gain in the sagittal and vertical planes was 5 ± 0.5 mm horizontally and 2 ± 0.5 mm (P < .001). Successful restoration was achieved in all patients with fixed implant-supported prostheses. Soft tissue complications occurred in 7 patients (35%). Complications after cementation of the crowns were seen in 3 implants (9.6%). All implants remained clinically osseointegrated at the end of the follow-up examination. There was no crestal bone loss around the implants beyond the first implant thread. Cancellous block allograft can be used successfully for post-traumatic implant-supported restoration in the anterior maxilla. Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  16. The role of spectral and temporal cues in voice gender discrimination by normal-hearing listeners and cochlear implant users.

    PubMed

    Fu, Qian-Jie; Chinchilla, Sherol; Galvin, John J

    2004-09-01

    The present study investigated the relative importance of temporal and spectral cues in voice gender discrimination and vowel recognition by normal-hearing subjects listening to an acoustic simulation of cochlear implant speech processing and by cochlear implant users. In the simulation, the number of speech processing channels ranged from 4 to 32, thereby varying the spectral resolution; the cutoff frequencies of the channels' envelope filters ranged from 20 to 320 Hz, thereby manipulating the available temporal cues. For normal-hearing subjects, results showed that both voice gender discrimination and vowel recognition scores improved as the number of spectral channels was increased. When only 4 spectral channels were available, voice gender discrimination significantly improved as the envelope filter cutoff frequency was increased from 20 to 320 Hz. For all spectral conditions, increasing the amount of temporal information had no significant effect on vowel recognition. Both voice gender discrimination and vowel recognition scores were highly variable among implant users. The performance of cochlear implant listeners was similar to that of normal-hearing subjects listening to comparable speech processing (4-8 spectral channels). The results suggest that both spectral and temporal cues contribute to voice gender discrimination and that temporal cues are especially important for cochlear implant users to identify the voice gender when there is reduced spectral resolution.

  17. Model validation of untethered, ultrasonic neural dust motes for cortical recording.

    PubMed

    Seo, Dongjin; Carmena, Jose M; Rabaey, Jan M; Maharbiz, Michel M; Alon, Elad

    2015-04-15

    A major hurdle in brain-machine interfaces (BMI) is the lack of an implantable neural interface system that remains viable for a substantial fraction of the user's lifetime. Recently, sub-mm implantable, wireless electromagnetic (EM) neural interfaces have been demonstrated in an effort to extend system longevity. However, EM systems do not scale down in size well due to the severe inefficiency of coupling radio-waves at those scales within tissue. This paper explores fundamental system design trade-offs as well as size, power, and bandwidth scaling limits of neural recording systems built from low-power electronics coupled with ultrasonic power delivery and backscatter communication. Such systems will require two fundamental technology innovations: (1) 10-100 μm scale, free-floating, independent sensor nodes, or neural dust, that detect and report local extracellular electrophysiological data via ultrasonic backscattering and (2) a sub-cranial ultrasonic interrogator that establishes power and communication links with the neural dust. We provide experimental verification that the predicted scaling effects follow theory; (127 μm)(3) neural dust motes immersed in water 3 cm from the interrogator couple with 0.002064% power transfer efficiency and 0.04246 ppm backscatter, resulting in a maximum received power of ∼0.5 μW with ∼1 nW of change in backscatter power with neural activity. The high efficiency of ultrasonic transmission can enable the scaling of the sensing nodes down to 10s of micrometer. We conclude with a brief discussion of the application of neural dust for both central and peripheral nervous system recordings, and perspectives on future research directions. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Dynamics of neural cryptography

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-15

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently,more » synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.« less

  19. Implant stability and marginal bone level of microgrooved zirconia dental implants: A 3-month experimental study on dogs.

    PubMed

    Delgado-Ruiz, Rafael Arcesio; Marković, Aleksa; Calvo-Guirado, José Luís; Lazić, Zoran; Piattelli, Adriano; Boticelli, Daniele; Maté-Sánchez, José Eduardo; Negri, Bruno; Ramírez-Fernández, María Piedad; Mišić, Tijana

    2014-05-01

    The modification of implant surfaces could affect mechanical implant stability as well as dynamics and quality of peri-implant bone healing. The aim of this 3-month experimental study in dogs was to investigate implant stability, marginal bone levels and bone tissue response to zirconia dental implants with two laser-micro-grooved intraosseous surfaces in comparison with nongrooved sandblasted zirconia and sandblasted, high-temperature etched titanium implants. Implant surface characterization was performed using optical interferometric profilometty and energy dispersive X-ray spectroscopy. A total of 96 implants (4 mm in diameter and 10 mm in length) were inserted randomly in both sides of the lower jaw of 12 Fox Hound dogs divided into groups of 24 each: the control (titanium), the group A (sandblasted zirconia), the group B (sandolasted zirconia plus microgrooved neck) and the group C (sandblasted zirconia plus all microgrooved). All the implants were immediately loaded. Insertion torque, periotest values, radiographic crestal bone level and removal torque were recorded during the 3-month follow-up. Qualitative scanning electon microscope (SEM) analysis of the bone-implant interfaces of each group was performed. Insertion torque values were higher in the group C and control implants (p < 0.05). Periotest values increased in all the periods in proportion to the extent of microgrooving as follows: the group C > the control > the group B > the group A (p < 0.05). Radiographic measurements showed minimal crestal bone loss at 3 months for microgrooved zirconia implants (groups C and B) and control implants compared with the group A implants (p < 0.05). The removal torque values increased with time for all the groups as follows: the group C > the control > the group B > the group A (p < 0.05). SEM showed that implant surfaces of the groups B and C had an extra bone growth inside the microgrooves that corresponded to the shape and direction of the microgrooves. The

  20. Fully integrated silicon probes for high-density recording of neural activity.

    PubMed

    Jun, James J; Steinmetz, Nicholas A; Siegle, Joshua H; Denman, Daniel J; Bauza, Marius; Barbarits, Brian; Lee, Albert K; Anastassiou, Costas A; Andrei, Alexandru; Aydın, Çağatay; Barbic, Mladen; Blanche, Timothy J; Bonin, Vincent; Couto, João; Dutta, Barundeb; Gratiy, Sergey L; Gutnisky, Diego A; Häusser, Michael; Karsh, Bill; Ledochowitsch, Peter; Lopez, Carolina Mora; Mitelut, Catalin; Musa, Silke; Okun, Michael; Pachitariu, Marius; Putzeys, Jan; Rich, P Dylan; Rossant, Cyrille; Sun, Wei-Lung; Svoboda, Karel; Carandini, Matteo; Harris, Kenneth D; Koch, Christof; O'Keefe, John; Harris, Timothy D

    2017-11-08

    Sensory, motor and cognitive operations involve the coordinated action of large neuronal populations across multiple brain regions in both superficial and deep structures. Existing extracellular probes record neural activity with excellent spatial and temporal (sub-millisecond) resolution, but from only a few dozen neurons per shank. Optical Ca 2+ imaging offers more coverage but lacks the temporal resolution needed to distinguish individual spikes reliably and does not measure local field potentials. Until now, no technology compatible with use in unrestrained animals has combined high spatiotemporal resolution with large volume coverage. Here we design, fabricate and test a new silicon probe known as Neuropixels to meet this need. Each probe has 384 recording channels that can programmably address 960 complementary metal-oxide-semiconductor (CMOS) processing-compatible low-impedance TiN sites that tile a single 10-mm long, 70 × 20-μm cross-section shank. The 6 × 9-mm probe base is fabricated with the shank on a single chip. Voltage signals are filtered, amplified, multiplexed and digitized on the base, allowing the direct transmission of noise-free digital data from the probe. The combination of dense recording sites and high channel count yielded well-isolated spiking activity from hundreds of neurons per probe implanted in mice and rats. Using two probes, more than 700 well-isolated single neurons were recorded simultaneously from five brain structures in an awake mouse. The fully integrated functionality and small size of Neuropixels probes allowed large populations of neurons from several brain structures to be recorded in freely moving animals. This combination of high-performance electrode technology and scalable chip fabrication methods opens a path towards recording of brain-wide neural activity during behaviour.

  1. A Rare Complication of Cochlear Implantation After Magnetic Resonance Imaging: Reversion of the Magnet.

    PubMed

    Öztürk, Erkan; Doruk, Can; Orhan, Kadir Serkan; Çelik, Mehmet; Polat, Beldan; Güldiken, Yahya

    2017-06-01

    Cochlear implants are mechanical devices used for patients with severe sensory-neural hearing loss, which has an inner magnet. It is proven that 1.5 Tesla magnetic resonance imaging (MRI) scanners are safe to use in patients with cochlear implant. In our patient, the authors aim to introduce a rare complication caused after a 1.5 Tesla MRI scanning and the management of this situation; the reversion of the magnet of the implant without displacement and significance of surgery in management.

  2. A Change in the Ion Selectivity of Ligand-Gated Ion Channels Provides a Mechanism to Switch Behavior.

    PubMed

    Pirri, Jennifer K; Rayes, Diego; Alkema, Mark J

    2015-01-01

    Behavioral output of neural networks depends on a delicate balance between excitatory and inhibitory synaptic connections. However, it is not known whether network formation and stability is constrained by the sign of synaptic connections between neurons within the network. Here we show that switching the sign of a synapse within a neural circuit can reverse the behavioral output. The inhibitory tyramine-gated chloride channel, LGC-55, induces head relaxation and inhibits forward locomotion during the Caenorhabditis elegans escape response. We switched the ion selectivity of an inhibitory LGC-55 anion channel to an excitatory LGC-55 cation channel. The engineered cation channel is properly trafficked in the native neural circuit and results in behavioral responses that are opposite to those produced by activation of the LGC-55 anion channel. Our findings indicate that switches in ion selectivity of ligand-gated ion channels (LGICs) do not affect network connectivity or stability and may provide an evolutionary and a synthetic mechanism to change behavior.

  3. Influence of Implant Shape (Tapered vs Cylindrical) on the Survival of Dental Implants Placed in the Posterior Maxilla: A Systematic Review.

    PubMed

    Alshehri, Mohammed; Alshehri, Fahad

    2016-12-01

    The aim of this review was to assess the effect of implant shape (tapered vs cylindrical) on the survival of dental implants placed in the posterior maxilla. Databases were searched from 1977 up to and including February 2015 using various key words. Only original clinical studies were included. Experimental studies, letters to the editor, review articles, case reports, and unpublished literature were excluded. The pattern of the present review was customized to mainly summarize the relevant information. Five studies were included. The number of patients included ranged between 4 and 29 participants. In total, 7 to 72 implants were placed in the posterior maxilla. Tapered and cylindrical shaped implants were placed in 1 and 1 study, respectively. In 1 study, both 41 tapered and cylindrical implant were placed. In all studies, rough-surfaced and threaded implants were used. Three studies reported the diameter and lengths of implants placed, which ranged between 3.75 to 4 mm and 10 to 20 mm, respectively. The mean follow-up period and survival rate of implants ranged between 19 and 96 months and 84.2% to 100%, respectively. In 1 study, implants were placed subcrestally in the posterior maxilla. Guided bone regeneration was performed in none of the studies. In all studies, participants were nonsmokers and were systemically healthy. There is no influence of implant shape on the survival of implants placed in the posterior maxilla.

  4. New Criteria of Indication and Selection of Patients to Cochlear Implant

    PubMed Central

    Sampaio, André L. L.; Araújo, Mercêdes F. S.; Oliveira, Carlos A. C. P.

    2011-01-01

    Numerous changes continue to occur in cochlear implant candidacy. In general, these have been accompanied by concomitant and satisfactory changes in surgical techniques. Together, this has advanced the utility and safety of cochlear implantation. Most devices are now approved for use in patients with severe to profound unilateral hearing loss rather then the prior requirement of a bilateral profound loss. Furthermore, studies have begun utilizing short electrode arrays for shallow insertion in patients with considerable low-frequency residual hearing. This technique will allow the recipient to continue to use acoustically amplified hearing for the low frequencies simultaneously with a cochlear implant for the high frequencies. The advances in design of, and indications for, cochlear implants have been matched by improvements in surgical techniques and decrease in complications. The resulting improvements in safety and efficacy have further encouraged the use of these devices. This paper will review the new concepts in the candidacy of cochlear implant. Medline data base was used to search articles dealing with the following topics: cochlear implant in younger children, cochlear implant and hearing preservation, cochlear implant for unilateral deafness and tinnitus, genetic hearing loss and cochlear implant, bilateral cochlear implant, neuropathy and cochlear implant and neural plasticity, and the selection of patients for cochlear implant. PMID:22013448

  5. Measurement of the single top production cross section in proton-antiproton collisions at 1.96 TeV

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tanasijczuk, Andres Jorge

    2010-03-25

    This thesis describes a search for singly produced top quarks via an electroweak vertex in head-on proton-antiproton collisions at a center of mass energy of √s = 1.96 TeV. The analysis uses a total of 2.3 fb -1 of data collected with the D0 detector at Fermilab, corresponding to two different run periods of the Tevatron collider. Two channels contribute to single top quark production at the Tevatron, the s-channel and the t-channel. In the s-channel, a virtual W boson is produced from the aniquilation of a quark and an antiquark and a top and a bottom quarks are produced from the W decay. The top quark decays almost exclusively into a W boson and a bottom quark. Final states are considered in which the W boson decays leptonically into an electron or a muon plus a neutrino. Thus, at the detector level, the final state characterizing the s-channel contains one lepton, missing energy accounting for the neutrino, and two jets from the two bottom quarks. In the t-channel, the final state has an additional jet coming from a light quark. Clearly, a precise reconstruction of the events requires a precise measurement of the energy of the jets. A multivariate technique, Bayesian neural networks, is used to extract the single top signal from the overwhelming background still left after event selection. A Bayesian likelihood probability is then computed to measure the single top cross section. Assuming the observed excess is due to single top events, the measured single top quark production cross section is σ(pmore » $$\\bar{p}$$ → tb + X, tqb + X) = 4.70 +1.18 -0.93 pb. The observed excess is associated with a p-value of (3.2 ± 2.3) x 10 -8, assuming the background-only hypothesis. This p-value corresponds to an excess over background of 5.4 standard deviations for a Gaussian density. The p-value computed using the standard model signal cross section of 3.46 pb is (22.7 ± 0.6) x 10 -6, corresponding to an expected significance of 4.08 standard deviations.« less

  6. Coronary Artery Diagnosis Aided by Neural Network

    NASA Astrophysics Data System (ADS)

    Stefko, Kamil

    2007-01-01

    Coronary artery disease is due to atheromatous narrowing and subsequent occlusion of the coronary vessel. Application of optimised feed forward multi-layer back propagation neural network (MLBP) for detection of narrowing in coronary artery vessels is presented in this paper. The research was performed using 580 data records from traditional ECG exercise test confirmed by coronary arteriography results. Each record of training database included description of the state of a patient providing input data for the neural network. Level and slope of ST segment of a 12 lead ECG signal recorded at rest and after effort (48 floating point values) was the main component of input data for neural network was. Coronary arteriography results (verified the existence or absence of more than 50% stenosis of the particular coronary vessels) were used as a correct neural network training output pattern. More than 96% of cases were correctly recognised by especially optimised and a thoroughly verified neural network. Leave one out method was used for neural network verification so 580 data records could be used for training as well as for verification of neural network.

  7. β-Decay Study of the rp-Process Nucleus ^96Cd

    NASA Astrophysics Data System (ADS)

    Becerril, Ana; Amthor, A.; Baumann, T.; Bazin, D.; Crawford, H.; Estrade, A.; Gade, A.; Ginter, T.; Guess, C.; Hausmann, M.; Hitt, G.; Lorusso, G.; Mantica, P.; Matos, M.; Meharchand, R.; Minamisono, K.; Montes, F.; Pereira, J.; Perdikakis, G.; Pinter, J.; Portillo, M.; Schatz, H.; Smith, K.; Stoker, J.; Zegers, R.

    2008-10-01

    The half-life of ^96Cd, one of the major waiting points along the reaction path of the rp-process [1] has been measured at NSCL. Nuclei of interest were produced by fragmentation of a 120 MeV/u ^112Sn primary beam on a Be target and selected with the A1900 fragment separator in conjunction with the RF Fragment Separator [2]. The experimental setup, which consisted on the NSCL β-Counting System [3] and the Segmented Germanium Array [4], permitted the correlation of implants and decays as well as the detection of both prompt and β-delayed γ-rays from implanted ions. Details of the experiment and results will be presented and their implications discussed. [1] H. Schatz et al., Phys. Rep. 294, 167 1998 [2] D. Gorelov et al. PAC 2005, Knoxville, TN, May 16-20 [3] J. Prisciandaro et al., NIM A 505, 140 2003 [4] W. Mueller et al., NIM A 466, 492 2001

  8. The influence of micro and macro-geometry in term of bone-implant interface in two implant systems: an histomorphometrical study.

    PubMed

    Rocci, A; Calcaterra, R; DI Girolamo, M; Rocci, M; Rocci, C; Baggi, L

    2015-01-01

    Many factors could affect the osseous healing of implants such as surface topography of biomaterial, the status of the bone/implant site, implant loading conditions, surgical technique and implant design. The aim of this study was to analyze the BIC of 2 different implants systems characterized by different micro and macrogeometry, that were placed in the posterior maxillary and mandibular jaws of humans, clinically unloaded and retrieved for histomorphometric analyses after 12 weeks. The patients were divided in two groups (Group I and II); group I was composed by 4 patients that each received in the posterior areas of mandible one type A implant [GTB-Plan1Health Amaro (UD) Italy] one type B implant (OsseoSpeed Astra Tech, Dentsply Molndal, Sweden). Group II was composed by 3 patients that each received in the posterior areas of jawsbone one type A implant [GTB-Plan1Health Amaro (UD) Italy] one type B implant (OsseoSpeed Astra Tech, Dentsply Molndal, Sweden). After 12 weeks of healing all the implants of both groups were harvested with the peri-implant bone tissues. Osseointegration process was evaluated throughout measurements of BIC. No statistical significance differences were found among the mean percentage of BIC of Group I - type A were 66,51% versus 49,96% in Group I - type B, as well as among the mean percentage of BIC of Group II - type A were 43.7% versus 60.02% in Group II - type B. Our results highlight that the mean percentage of BIC after 12 weeks from the implants placement without functional loading is not influenced by the composition of the implant surface.

  9. Design and testing of an advanced implantable neuroprosthesis with myoelectric control.

    PubMed

    Hart, Ronald L; Bhadra, Niloy; Montague, Fred W; Kilgore, Kevin L; Peckham, P Hunter

    2011-02-01

    An implantable stimulator-telemeter (IST-12) was developed for applications in neuroprosthetic restoration of limb function in paralyzed individuals. The IST-12 provides 12 stimulation channels and two myoelectric signal (MES) channels. The MES circuitry includes a two-channel multiplexer, preamplifier, variable gain amplifier/bandpass filter, full-wave rectifier, and bin integrator. Power and control signals are transmitted from an external control unit to the IST-12 through an inductive link. Recorded MES signals are telemetered back to the external control unit through the same inductive link. Following bench testing, one device was implanted chronically in a dog for 15 months and evaluated. Conditions were identified in which MES could be recorded with minimal stimulus artifact. The ability to record MES in the presence of stimulation was verified, confirming the potential of the IST-12 to be used as a myoelectric controlled neuroprosthesis.

  10. Bringing Hearing to the Deaf--Cochlear Implants: a Technical and Personal Account

    NASA Astrophysics Data System (ADS)

    Shipsey, Ian

    2006-04-01

    Cochlear implants are the first device to successfully restore neural function. They have instigated a popular but controversial revolution in the treatment of deafness, and they serve as a model for research in neuroscience and biomedical engineering. In this talk the physiology of natural hearing will be reviewed from the perspective of a physicist, and the function of cochlear implants will be described in the context of historical treatments, electrical engineering, psychophysics, clinical evaluation of efficacy and personal experience. The social implications of cochlear implantation and the future outlook for auditory prostheses will also be discussed.

  11. Fatty acids and related Kv2 channel blockers: electrophysiology and toxicity on mosquitoes

    USDA-ARS?s Scientific Manuscript database

    Ligand-gated ion channels form an important superfamily of proteins involved in many biological processes. Among them, the potassium channels constitute a very diverse group involved in neural signaling, neuronal activity and action potential. Among the different types of channel activation, voltage...

  12. Al-implanted on-axis 4H-SiC MOSFETs

    NASA Astrophysics Data System (ADS)

    Florentin, M.; Cabello, M.; Rebollo, J.; Montserrat, J.; Brosselard, P.; Henry, A.; Godignon, P.

    2017-03-01

    In this paper, the impact of temperature and time stress on gate oxide stability of several multi-implanted and epitaxied 4H-SiC nMOSFET is presented. The oxide layer was processed under a rapid thermal process (RTP) furnace. The variation of the main electrical parameters is shown. We report the high quality and stability of such implanted MOSFETs, and point out the very low roughness effect of the on-axis-cut sample. Particularly, in the best case, effective channel mobility (μ fe) overcomes 20 cm2.V-1.s-1 at 300 °C for a channel length of 12 μm, which is very encouraging for implantation technology. Starting from 200 °C, the apparent increase of the μ fe peak of the MOSFET ceases and tends to saturate with further temperature increase. This is an indication of the potential of MOSFETs built on on-axis substrates. Thus, starting from the real case of an implanted MOSFET, the global purpose is to show that the electrical performance of such an on-axis-built device can tend to reach that of the ideal case, i.e. epitaxied MOSFET, and even overcome its electrical limitation, e.g. in terms of threshold voltage stability at high temperature.

  13. Pulse Coupled Neural Networks for the Segmentation of Magnetic Resonance Brain Images.

    DTIC Science & Technology

    1996-12-01

    PULSE COUPLED NEURAL NETWORKS FOR THE SEGMENTATION OF MAGNETIC RESONANCE BRAIN IMAGES THESIS Shane Lee Abrahamson First Lieutenant, USAF AFIT/GCS/ENG...COUPLED NEURAL NETWORKS FOR THE SEGMENTATION OF MAGNETIC RESONANCE BRAIN IMAGES THESIS Shane Lee Abrahamson First Lieutenant, USAF AFIT/GCS/ENG/96D-01...research develops an automated method for segmenting Magnetic Resonance (MR) brain images based on Pulse Coupled Neural Networks (PCNN). MR brain image

  14. A Psychophysics experimental software to evaluate electrical pitch discrimination in Nucleus cochlear implanted patients

    NASA Astrophysics Data System (ADS)

    Pérez Zaballos, M. T.; Ramos de Miguel, A.; Killian, M.; Ramos Macías, A.

    2016-02-01

    Multichannel electrode array design in cochlear implants has evolved into two major categories: straight and perimodiolar electrodes. When implanted, the former lies along the outer wall of the scala tympani, while the later are located closer to the modiolus, where the neural ends are. Therefore, a perimodiolar position of the electrode array could be expected to result in reduced stimulus thresholds and stimulating currents, increased dynamic range, and more localized stimulation of the neural elements. However, their advantage for pitch discrimination has not been conclusively stated. Therefore, in order to study electrode independence, a psychophysical software has been developed, making use of Nucleus Implant Communicator tools provided by Cochlear company under a research agreement. The application comprises a graphical interface to facilitate its use, since previous software has always required some type of computer language skills. It allows for customization of electrical pulse parameters, measurement of threshold and comfort levels, loudness balancing and alternative forced choice experiments to determine electrode discrimination in Nucleus© users.

  15. Computational Evaluation of Cochlear Implant Surgery Outcomes Accounting for Uncertainty and Parameter Variability.

    PubMed

    Mangado, Nerea; Pons-Prats, Jordi; Coma, Martí; Mistrík, Pavel; Piella, Gemma; Ceresa, Mario; González Ballester, Miguel Á

    2018-01-01

    Cochlear implantation (CI) is a complex surgical procedure that restores hearing in patients with severe deafness. The successful outcome of the implanted device relies on a group of factors, some of them unpredictable or difficult to control. Uncertainties on the electrode array position and the electrical properties of the bone make it difficult to accurately compute the current propagation delivered by the implant and the resulting neural activation. In this context, we use uncertainty quantification methods to explore how these uncertainties propagate through all the stages of CI computational simulations. To this end, we employ an automatic framework, encompassing from the finite element generation of CI models to the assessment of the neural response induced by the implant stimulation. To estimate the confidence intervals of the simulated neural response, we propose two approaches. First, we encode the variability of the cochlear morphology among the population through a statistical shape model. This allows us to generate a population of virtual patients using Monte Carlo sampling and to assign to each of them a set of parameter values according to a statistical distribution. The framework is implemented and parallelized in a High Throughput Computing environment that enables to maximize the available computing resources. Secondly, we perform a patient-specific study to evaluate the computed neural response to seek the optimal post-implantation stimulus levels. Considering a single cochlear morphology, the uncertainty in tissue electrical resistivity and surgical insertion parameters is propagated using the Probabilistic Collocation method, which reduces the number of samples to evaluate. Results show that bone resistivity has the highest influence on CI outcomes. In conjunction with the variability of the cochlear length, worst outcomes are obtained for small cochleae with high resistivity values. However, the effect of the surgical insertion length on the

  16. Beamforming approaches for untethered, ultrasonic neural dust motes for cortical recording: a simulation study.

    PubMed

    Bertrand, Alexander; Seo, Dongjin; Maksimovic, Filip; Carmena, Jose M; Maharbiz, Michel M; Alon, Elad; Rabaey, Jan M

    2014-01-01

    In this paper, we examine the use of beamforming techniques to interrogate a multitude of neural implants in a distributed, ultrasound-based intra-cortical recording platform known as Neural Dust. We propose a general framework to analyze system design tradeoffs in the ultrasonic beamformer that extracts neural signals from modulated ultrasound waves that are backscattered by free-floating neural dust (ND) motes. Simulations indicate that high-resolution linearly-constrained minimum variance beamforming sufficiently suppresses interference from unselected ND motes and can be incorporated into the ND-based cortical recording system.

  17. Ultra-low noise miniaturized neural amplifier with hardware averaging.

    PubMed

    Dweiri, Yazan M; Eggers, Thomas; McCallum, Grant; Durand, Dominique M

    2015-08-01

    associated with the miniaturized contacts and the high channel count in electrode arrays. This technique can be adopted for other applications where miniaturized and implantable multichannel acquisition systems with ultra-low noise and low power are required.

  18. Prevalence, Etiology and Treatment of Peri-Implant Mucositis and Peri-Implantitis: A Survey of Periodontists in the United States.

    PubMed

    Papathanasiou, Evangelos; Finkelman, Matthew; Hanley, James; Parashis, Andreas O

    2016-05-01

    Currently, information available on the exact prevalence and standard therapeutic protocol of peri-implant diseases is insufficient. The aim of this survey was to investigate the perceived prevalence, etiology, and management of peri-implant mucositis and peri-implantitis by periodontists in the United States. A twenty-question survey was developed. Periodontists currently practicing in the United States were contacted by an e-mail that contained a link to access the survey. Two hundred eighty periodontists (79.3% males; 62.9% with >10 years in practice, 75.7% in private practice) completed the survey. Most (96.1%) of the participants were placing implants (58.3% for >10 years and 32.4% >150 implants/year). The majority reported that the prevalence of peri-implant mucositis and peri-implantitis in their practices is up to 25% but is higher in the general US population and that up to 10% of implants must be removed due to peri-implantitis. There was agreement among contributing etiologic factors such as: 1) plaque; 2) smoking; 3) adverse loading; 4) oral hygiene; 5) use of antimicrobial gel/mouthrinse; 6) non-surgical debridement; 7) use of systemic antibiotics; and 8) 3-month supportive care for treatment of peri-implantitis. Significant heterogeneity was recorded in relation to the instruments used for debridement, use and type of surgical treatment, and materials used for regeneration. Only 5.1% believed that treatment is very effective. This survey indicates that peri-implant diseases are a frequently encountered problem in periodontal practices and that the absence of a standard therapeutic protocol results in significant empirical use of therapeutic modalities and a moderately effective treatment outcome.

  19. New cochlear implant research coding strategy based on the MP3(000™) strategy to reintroduce the virtual channel effect.

    PubMed

    Neben, Nicole; Lenarz, Thomas; Schuessler, Mark; Harpel, Theo; Buechner, Andreas

    2013-05-01

    Results for speech recognition in noise tests when using a new research coding strategy designed to introduce the virtual channel effect provided no advantage over MP3(000™). Although statistically significant smaller just noticeable differences (JNDs) were obtained, the findings for pitch ranking proved to have little clinical impact. The aim of this study was to explore whether modifications to MP3000 by including sequential virtual channel stimulation would lead to further improvements in hearing, particularly for speech recognition in background noise and in competing-talker conditions, and to compare results for pitch perception and melody recognition, as well as informally collect subjective impressions on strategy preference. Nine experienced cochlear implant subjects were recruited for the prospective study. Two variants of the experimental strategy were compared to MP3000. The study design was a single-blinded ABCCBA cross-over trial paradigm with 3 weeks of take-home experience for each user condition. Comparing results of pitch-ranking, a significantly reduced JND was identified. No significant effect of coding strategy on speech understanding in noise or competing-talker materials was found. Melody recognition skills were the same under all user conditions.

  20. Neurotrophic Electrode: Method of assembly and implantation into human motor speech cortex

    PubMed Central

    Bartels, Jess; Andreasen, Dinal; Ehirim, Princewill; Mao, Hui; Seibert, Steven; Wright, E Joe; Kennedy, Philip

    2008-01-01

    The Neurotrophic Electrode (NE) is designed for longevity and stability of recorded signals. To achieve this aim it induces neurites to grow through its glass tip, thus anchoring it in neuropil. The glass tip contains insulated gold wires for recording the activity of the myelinated neurites that grow into the tip. Neural signals inside the tip are electrically insulated from surrounding neural activity by the glass. The most recent version of the electrode has four wires inside its tip to maximize the number of discriminable signals recorded from ingrown neurites, and has a miniature connector. Flexible coiled, insulated gold wires connect to electronics on the skull that remain subcutaneous. The implanted electronics consist of differential amplifiers, FM transmitters, and a sine wave at power up for tuning and calibration. Inclusion criteria for selecting locked-in subjects include medical stability, normal cognition, and strong caregiver support. The implant target is localized via an fMRI-naming task. Final localization at surgery is achieved by 3D stereotaxic localization. During recording, implanted electronics are powered by magnetic induction across an air gap. Coiled antennas placed on the scalp over the implanted transmitters receive the amplified FM transmitter outputs. Data is processed as described elsewhere where stability and longevity issues are addressed. Five subjects have been successfully implanted with the NE. Recorded signals persisted for over four years in two subjects who died from underlying illnesses, and continue for over three years in our present subject. PMID:18672003

  1. In Vivo Validation of Custom-Designed Silicon-Based Microelectrode Arrays for Long-Term Neural Recording and Stimulation

    PubMed Central

    Manoonkitiwongsa, Panya S.; Wang, Cindy X.; McCreery, Douglas B.

    2012-01-01

    We developed and validated silicon-based neural probes for neural stimulating and recording in long-term implantation in the brain. The probes combine the deep reactive ion etching process and mechanical shaping of their tip region, yielding a mechanically sturdy shank with a sharpened tip to reduce insertion force into the brain and spinal cord, particularly, with multiple shanks in the same array. The arrays’ insertion forces have been quantified in vitro. Five consecutive chronically-implanted devices were fully functional from 3 to 18 months. The microelectrode sites were electroplated with iridium oxide, and the charge injection capacity measurements were performed both in vitro and after implantation in the adult feline brain. The functionality of the chronic array was validated by stimulating in the cochlear nucleus and recording the evoked neuronal activity in the central nucleus of the inferior colliculus. The arrays’ recording quality has also been quantified in vivo with neuronal spike activity recorded up to 566 days after implantation. Histopathology evaluation of neurons and astrocytes using immunohistochemical stains indicated minimal alterations of tissue architecture after chronic implantation. PMID:22020666

  2. Clinical and Radiologic Outcomes of Submerged and Nonsubmerged Bone-Level Implants with Internal Hexagonal Connections in Immediate Implantation: A 5-Year Retrospective Study.

    PubMed

    Wu, Shiyu; Wu, Xiayi; Shrestha, Rachana; Lin, Jinying; Feng, Zhicai; Liu, Yudong; Shi, Yunlin; Huang, Baoxin; Li, Zhipeng; Liu, Quan; Zhang, Xiaocong; Hu, Mingxuan; Chen, Zhuofan

    2018-02-01

    To evaluate the 5-year clinical and radiologic outcome of immediate implantation using submerged and nonsubmerged techniques with bone-level implants and internal hexagonal connections and the effects of potential influencing factors. A total of 114 bone-level implants (XiVE S plus) with internal hexagonal connections inserted into 72 patients were included. Patients were followed up for 5 years. A t-test was used to statistically evaluate the marginal bone loss between the submerged and nonsubmerged groups. The cumulative survival rate (CSR) was calculated according to the life table method and illustrated with Kaplan-Meier survival curves. Comparisons of the CSR between healing protocols, guided bone regeneration, implants with different sites, lengths, and diameters were performed using log-rank tests. The 5-year cumulative implant survival rates with submerged and nonsubmerged healing were 94% and 96%, respectively. No statistically significant differences in terms of marginal bone loss, healing protocol, application of guided bone regeneration, implant site, or length were observed. High CSRs and good marginal bone levels were achieved 5 years after immediate implantation of bone-level implants with internal hexagonal connections using both the submerged and nonsubmerged techniques. Factors such as implant length, site, and application of guided bone regeneration did not have an impact on the long-term success of the implants. © 2017 by the American College of Prosthodontists.

  3. Listening to Brain Microcircuits for Interfacing With External World—Progress in Wireless Implantable Microelectronic Neuroengineering Devices

    PubMed Central

    Nurmikko, Arto V.; Donoghue, John P.; Hochberg, Leigh R.; Patterson, William R.; Song, Yoon-Kyu; Bull, Christopher W.; Borton, David A.; Laiwalla, Farah; Park, Sunmee; Ming, Yin; Aceros, Juan

    2011-01-01

    Acquiring neural signals at high spatial and temporal resolution directly from brain microcircuits and decoding their activity to interpret commands and/or prior planning activity, such as motion of an arm or a leg, is a prime goal of modern neurotechnology. Its practical aims include assistive devices for subjects whose normal neural information pathways are not functioning due to physical damage or disease. On the fundamental side, researchers are striving to decipher the code of multiple neural microcircuits which collectively make up nature’s amazing computing machine, the brain. By implanting biocompatible neural sensor probes directly into the brain, in the form of microelectrode arrays, it is now possible to extract information from interacting populations of neural cells with spatial and temporal resolution at the single cell level. With parallel advances in application of statistical and mathematical techniques tools for deciphering the neural code, extracted populations or correlated neurons, significant understanding has been achieved of those brain commands that control, e.g., the motion of an arm in a primate (monkey or a human subject). These developments are accelerating the work on neural prosthetics where brain derived signals may be employed to bypass, e.g., an injured spinal cord. One key element in achieving the goals for practical and versatile neural prostheses is the development of fully implantable wireless microelectronic “brain-interfaces” within the body, a point of special emphasis of this paper. PMID:21654935

  4. Auditory Responses to Electric and Infrared Neural Stimulation of the Rat Cochlear Nucleus

    PubMed Central

    Verma, Rohit; Guex, Amelie A.; Hancock, Kenneth E.; Durakovic, Nedim; McKay, Colette M.; Slama, Michaël C. C.; Brown, M. Christian; Lee, Daniel J.

    2014-01-01

    In an effort to improve the auditory brainstem implant, a prosthesis in which user outcomes are modest, we applied electric and infrared neural stimulation (INS) to the cochlear nucleus in a rat animal model. Electric stimulation evoked regions of neural activation in the inferior colliculus and short-latency, multipeaked auditory brainstem responses (ABRs). Pulsed INS, delivered to the surface of the cochlear nucleus via an optical fiber, evoked broad neural activation in the inferior colliculus. Strongest responses were recorded when the fiber was placed at lateral positions on the cochlear nucleus, close to the temporal bone. INS-evoked ABRs were multipeaked but longer in latency than those for electric stimulation; they resembled the responses to acoustic stimulation. After deafening, responses to electric stimulation persisted, whereas those to INS disappeared, consistent with a reported “optophonic” effect, a laser-induced acoustic artifact. Thus, for deaf individuals who use the auditory brainstem implant, INS alone did not appear promising as a new approach. PMID:24508368

  5. Cochlear implantation in children and adults in Switzerland.

    PubMed

    Brand, Yves; Senn, Pascal; Kompis, Martin; Dillier, Norbert; Allum, John H J

    2014-02-04

    The cochlear implant (CI) is one of the most successful neural prostheses developed to date. It offers artificial hearing to individuals with profound sensorineural hearing loss and with insufficient benefit from conventional hearing aids. The first implants available some 30 years ago provided a limited sensation of sound. The benefit for users of these early systems was mostly a facilitation of lip-reading based communication rather than an understanding of speech. Considerable progress has been made since then. Modern, multichannel implant systems feature complex speech processing strategies, high stimulation rates and multiple sites of stimulation in the cochlea. Equipped with such a state-of-the-art system, the majority of recipients today can communicate orally without visual cues and can even use the telephone. The impact of CIs on deaf individuals and on the deaf community has thus been exceptional. To date, more than 300,000 patients worldwide have received CIs. In Switzerland, the first implantation was performed in 1977 and, as of 2012, over 2,000 systems have been implanted with a current rate of around 150 CIs per year. The primary purpose of this article is to provide a contemporary overview of cochlear implantation, emphasising the situation in Switzerland.

  6. Effects of an implantable two-channel peroneal nerve stimulator versus conventional walking device on spatiotemporal parameters and kinematics of hemiparetic gait.

    PubMed

    Kottink, Anke I R; Tenniglo, Martin J B; de Vries, Wiebe H K; Hermens, Hermie J; Buurke, Jaap H

    2012-01-01

    The aims of this study were: (i) to compare the neuro-prosthetic effect of implantable peroneal nerve stimulation to the orthotic effect of a standard of care intervention (no device, shoe or ankle foot orthosis) on walking, as assessed by spatiotemporal parameters; and (ii) to examine whether there is evidence of an enhanced lower-limb flexion reflex with peroneal nerve stimulation and compare the kinematic effect of an implantable peroneal nerve stimulation device vs standard of care intervention on initial loading response of the paretic limb, as assessed by hip, knee and ankle kinematics. Randomized controlled trial. A total of 23 chronic stroke survivors with drop foot. The intervention group received an implantable 2-channel peroneal nerve stimulator for correction of drop foot. The control group continued using a conventional walking device. Spatiotemporal parameters and hip, knee and ankle kinematics were measured while subjects walked with the device on using a 3-dimensional video camera system during baseline and after a follow-up period of 26 weeks. Peroneal nerve stimulation normalized stance and double support of the paretic limb and single support of the non-paretic limb, in comparison with using a conventional walking device. In addition, peroneal nerve stimulation is more effective to provide ankle dorsiflexion during swing and resulted in a normalized initial loading response. Although peroneal nerve stimulation and ankle foot orthosis are both prescribed to correct a drop foot in the same patient population, spatiotemporal parameters, dorsiflexion during swing and loading response are influenced in a functionally different way.

  7. Listening to Brain Microcircuits for Interfacing With External World-Progress in Wireless Implantable Microelectronic Neuroengineering Devices: Experimental systems are described for electrical recording in the brain using multiple microelectrodes and short range implantable or wearable broadcasting units.

    PubMed

    Nurmikko, Arto V; Donoghue, John P; Hochberg, Leigh R; Patterson, William R; Song, Yoon-Kyu; Bull, Christopher W; Borton, David A; Laiwalla, Farah; Park, Sunmee; Ming, Yin; Aceros, Juan

    2010-01-01

    Acquiring neural signals at high spatial and temporal resolution directly from brain microcircuits and decoding their activity to interpret commands and/or prior planning activity, such as motion of an arm or a leg, is a prime goal of modern neurotechnology. Its practical aims include assistive devices for subjects whose normal neural information pathways are not functioning due to physical damage or disease. On the fundamental side, researchers are striving to decipher the code of multiple neural microcircuits which collectively make up nature's amazing computing machine, the brain. By implanting biocompatible neural sensor probes directly into the brain, in the form of microelectrode arrays, it is now possible to extract information from interacting populations of neural cells with spatial and temporal resolution at the single cell level. With parallel advances in application of statistical and mathematical techniques tools for deciphering the neural code, extracted populations or correlated neurons, significant understanding has been achieved of those brain commands that control, e.g., the motion of an arm in a primate (monkey or a human subject). These developments are accelerating the work on neural prosthetics where brain derived signals may be employed to bypass, e.g., an injured spinal cord. One key element in achieving the goals for practical and versatile neural prostheses is the development of fully implantable wireless microelectronic "brain-interfaces" within the body, a point of special emphasis of this paper.

  8. Current steering and current focusing in cochlear implants: comparison of monopolar, tripolar, and virtual channel electrode configurations.

    PubMed

    Berenstein, Carlo K; Mens, Lucas H M; Mulder, Jef J S; Vanpoucke, Filiep J

    2008-04-01

    To compare the effects of Monopole (Mono), Tripole (Tri), and "Virtual channel" (Vchan) electrode configurations on spectral resolution and speech perception in a crossover design. Nine experienced adults who received an Advanced Bionics CII/90K cochlear implant participated in a crossover design using three experimental strategies for 2 wk each. Three strategies were compared: (1) Mono; (2) Tri with current partly returning to adjacent electrodes and partly (25 or 75%) to the extracochlear reference; and (3) a monopolar "Vchan" strategy creating seven intermediate channels between two contacts. Each strategy was a variant of the standard "HiRes" processing strategy using 14 channels and 1105 pulses/sec/ channel, and a pulse duration of 32 microsec/phase. Spectral resolution was measured using broadband noise with a sinusoidally rippled spectral envelope with peaks evenly spaced on a logarithmic frequency scale. Speech perception was measured for monosyllables in quiet and in steady-state and fluctuating noises. Subjective comments on music experience and preferences in everyday use were assessed through questionnaires. Thresholds and most comfortable levels with Mono and Vchan were both significantly lower than levels with Tri. Spectral resolution was significantly higher with Tri than with Mono; spectral resolution with Vchan did not differ significantly from the other configurations. Moderate but significant correlations between word recognition and spectral resolution were found in speech in quiet and fluctuating noise. For speech in quiet, word recognition was best with Mono and worst with Vchan; Tri did not significantly differ from the other configurations. Pooled across the noise conditions, word recognition was best with Tri and worst with Vchan (Mono did not significantly differ from the other configurations). These differences were small and insufficient to result in a clear increase in performance across subjects if the result from the best

  9. An introduction to neural networks surgery, a field of neuromodulation which is based on advances in neural networks science and digitised brain imaging.

    PubMed

    Sakas, D E; Panourias, I G; Simpson, B A

    2007-01-01

    Operative Neuromodulation is the field of altering electrically or chemically the signal transmission in the nervous system by implanted devices in order to excite, inhibit or tune the activities of neurons or neural networks and produce therapeutic effects. The present article reviews relevant literature on procedures or devices applied either in contact with the cerebral cortex or cranial nerves or in deep sites inside the brain in order to treat various refractory neurological conditions such as: a) chronic pain (facial, somatic, deafferentation, phantom limb), b) movement disorders (Parkinson's disease, dystonia, Tourette syndrome), c) epilepsy, d) psychiatric disease, e) hearing deficits, and f) visual loss. These data indicate that in operative neuromodulation, a new field emerges that is based on neural networks research and on advances in digitised stereometric brain imaging which allow precise localisation of cerebral neural networks and their relay stations; this field can be described as Neural networks surgery because it aims to act extrinsically or intrinsically on neural networks and to alter therapeutically the neural signal transmission with the use of implantable electrical or electronic devices. The authors also review neurotechnology literature relevant to neuroengineering, nanotechnologies, brain computer interfaces, hybrid cultured probes, neuromimetics, neuroinformatics, neurocomputation, and computational neuromodulation; the latter field is dedicated to the study of the biophysical and mathematical characteristics of electrochemical neuromodulation. The article also brings forward particularly interesting lines of research such as the carbon nanofibers electrode arrays for simultaneous electrochemical recording and stimulation, closed-loop systems for responsive neuromodulation, and the intracortical electrodes for restoring hearing or vision. The present review of cerebral neuromodulatory procedures highlights the transition from the

  10. The influence of micro and macro-geometry in term of bone-implant interface in two implant systems: an histomorphometrical study

    PubMed Central

    ROCCI, A.; CALCATERRA, R.; DI GIROLAMO, M.; ROCCI, M.; ROCCI, C.; BAGGI, L.

    2015-01-01

    SUMMARY Objective Many factors could affect the osseous healing of implants such as surface topography of biomaterial, the status of the bone/implant site, implant loading conditions, surgical technique and implant design. The aim of this study was to analyze the BIC of 2 different implants systems characterized by different micro and macrogeometry, that were placed in the posterior maxillary and mandibular jaws of humans, clinically unloaded and retrieved for histomorphometric analyses after 12 weeks. Material and method The patients were divided in two groups (Group I and II); group I was composed by 4 patients that each received in the posterior areas of mandible one type A implant [GTB-Plan1Health Amaro (UD) Italy] one type B implant (OsseoSpeed Astra Tech, Dentsply Molndal, Sweden). Group II was composed by 3 patients that each received in the posterior areas of jawsbone one type A implant [GTB-Plan1Health Amaro (UD) Italy] one type B implant (OsseoSpeed Astra Tech, Dentsply Molndal, Sweden). After 12 weeks of healing all the implants of both groups were harvested with the peri-implant bone tissues. Osseointegration process was evaluated throughout measurements of BIC. Results No statistical significance differences were found among the mean percentage of BIC of Group I – type A were 66,51% versus 49,96% in Group I – type B, as well as among the mean percentage of BIC of Group II – type A were 43.7% versus 60.02% in Group II – type B. Conclusions Our results highlight that the mean percentage of BIC after 12 weeks from the implants placement without functional loading is not influenced by the composition of the implant surface. PMID:28042421

  11. Revised analysis of Ca 40 + Zr 96 fusion reactions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Esbensen, H.; Montagnoli, G.; Stefanini, A. M.

    2016-03-10

    Fusion data for 40Ca + 96Zr are analyzed by coupled-channels calculations that are based on a standard Woods-Saxon potential and include couplings to multiphonon excitations and transfer channels. The couplings to multiphonon excitations are the same as those used in a previous work. The transfer couplings are calibrated to reproduce the measured neutron transfer data. This type of calculation gives a poor fit to the fusion data. However, by multiplying the transfer couplings with a √2 one obtains an excellent fit. Finally, the scaling of the transfer strengths is supposed to simulate the combined effect of neutron and proton transfer,more » and the calculated one- and two-nucleon transfer cross sections are indeed in reasonable agreement with the measured cross sections.« less

  12. Neural networks for Higgs physics

    NASA Astrophysics Data System (ADS)

    Tentindo-Repond, Silvia; Bhat, Pushpalatha C.; Prosper, Harrison B.

    2001-08-01

    The main application of neural networks (NN) in Higgs physics so far has been to optimize the signal over background ratio. The positive result obtained imply that the use of NN will lead to a big reduction in the integrated luminosity required for the discovery of the Higgs in RunII. Neural Networks have also been recently used in Higgs physics to set up tagging algorithms to identify the heavy flavor content of jets. Whereas in the previous studies the NN b-tagging methods used are channel-independent, a channel-dependent method has been used in the present work. The signal pp¯→WH→lνbb¯ has been studied against the dominant background pp¯→Wbb¯, in an attempt to improve the signal over background ratio by trying to push the invariant mass of the background events further away from the signal. This result would get the equivalent effect of an improved mass resolution.

  13. Fiber-optic bending sensor for cochlear implantation

    NASA Astrophysics Data System (ADS)

    Li, Enbang; Yao, Jianquan

    2006-09-01

    Cochlear implantation has been proved as a great success in treating profound sensorineural deafness in both children and adults. Cochlear electrode array implantation is a complex and delicate surgical process. Surgically induced damage to the inner wall of the scala tympani could happen if the insertion angle of the electrode is incorrect and an excessive insertion force is applied to the electrode. This damage could lead to severe degeneration of the remaining neural elements. It is therefore of vital importance to monitor the shape and position of the electrode during the implantation surgery. In this paper, we report a fiber-optic bending sensor which can be integrated with the electrode and used to guide the implantation process. The sensor consists of a piece of optical fiber. The end of the fiber is coated with aluminum layer to form a mirror. Bending the fiber with the electrode introduces loss to the light transmitting in the fiber. By detecting the power of the reflected light, we can detennine the bending happened to the fiber, and consequently measure the curved shape of the electrode. Experimental results show that the proposed fiber sensor is a promising technique to make in-situ monitoring of the shape and position of the electrode during the implantation process.

  14. Self-organization of helium precipitates into elongated channels within metal nanolayers

    PubMed Central

    Chen, Di; Li, Nan; Yuryev, Dina; Baldwin, J. Kevin; Wang, Yongqiang; Demkowicz, Michael J.

    2017-01-01

    Material degradation due to precipitation of implanted helium (He) is a key concern in nuclear energy. Decades of research have mapped out the fate of He precipitates in metals, from nucleation and growth of equiaxed bubbles and voids to formation and bursting of surface blisters. By contrast, we show that He precipitates confined within nanoscale metal layers depart from their classical growth trajectories: They self-organize into elongated channels. These channels form via templated nucleation of He precipitates along layer surfaces followed by their growth and spontaneous coalescence into stable precipitate lines. The total line length and connectivity increases with the amount of implanted He, indicating that these channels ultimately interconnect into percolating “vascular” networks. Vascularized metal composites promise a transformative solution to He-induced damage by enabling in operando outgassing of He and other impurities while maintaining material integrity. PMID:29152573

  15. The neural processing of taste

    PubMed Central

    Lemon, Christian H; Katz, Donald B

    2007-01-01

    Although there have been many recent advances in the field of gustatory neurobiology, our knowledge of how the nervous system is organized to process information about taste is still far from complete. Many studies on this topic have focused on understanding how gustatory neural circuits are spatially organized to represent information about taste quality (e.g., "sweet", "salty", "bitter", etc.). Arguments pertaining to this issue have largely centered on whether taste is carried by dedicated neural channels or a pattern of activity across a neural population. But there is now mounting evidence that the timing of neural events may also importantly contribute to the representation of taste. In this review, we attempt to summarize recent findings in the field that pertain to these issues. Both space and time are variables likely related to the mechanism of the gustatory neural code: information about taste appears to reside in spatial and temporal patterns of activation in gustatory neurons. What is more, the organization of the taste network in the brain would suggest that the parameters of space and time extend to the neural processing of gustatory information on a much grander scale. PMID:17903281

  16. Neural correlates of behavioral amplitude modulation sensitivity in the budgerigar midbrain

    PubMed Central

    Neilans, Erikson G.; Abrams, Kristina S.; Idrobo, Fabio; Carney, Laurel H.

    2016-01-01

    Amplitude modulation (AM) is a crucial feature of many communication signals, including speech. Whereas average discharge rates in the auditory midbrain correlate with behavioral AM sensitivity in rabbits, the neural bases of AM sensitivity in species with human-like behavioral acuity are unexplored. Here, we used parallel behavioral and neurophysiological experiments to explore the neural (midbrain) bases of AM perception in an avian speech mimic, the budgerigar (Melopsittacus undulatus). Behavioral AM sensitivity was quantified using operant conditioning procedures. Neural AM sensitivity was studied using chronically implanted microelectrodes in awake, unrestrained birds. Average discharge rates of multiunit recording sites in the budgerigar midbrain were insufficient to explain behavioral sensitivity to modulation frequencies <100 Hz for both tone- and noise-carrier stimuli, even with optimal pooling of information across recording sites. Neural envelope synchrony, in contrast, could explain behavioral performance for both carrier types across the full range of modulation frequencies studied (16–512 Hz). The results suggest that envelope synchrony in the budgerigar midbrain may underlie behavioral sensitivity to AM. Behavioral AM sensitivity based on synchrony in the budgerigar, which contrasts with rate-correlated behavioral performance in rabbits, raises the possibility that envelope synchrony, rather than average discharge rate, might also underlie AM perception in other species with sensitive AM detection abilities, including humans. These results highlight the importance of synchrony coding of envelope structure in the inferior colliculus. Furthermore, they underscore potential benefits of devices (e.g., midbrain implants) that evoke robust neural synchrony. PMID:26843608

  17. Measurement of the Single Top Quark Cross Section in the Lepton Plus Jets Final State in Proton-Antiproton Collisions at a Center of Mass Energy of 1.96 TeV Using the CDF II Detector

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, Zhenbin

    2012-01-01

    We present a measurement of the single top quark cross section in the lepton plus jets final state using an integrated luminosity corresponding to 7.5 fb -1 of p\\bar p collision data collected by the Collider Detector at Fermilab. The single top candidate events are identified by the signature of a charged lepton, large missing transverse energy, and two or three jets with at least one of them identified as originating from a bottom quark. A new Monte Carlo generator POWHEG is used to model the single top quark production processes, which include s-channel, t-channel, and Wt-channel. A neural network multivariate method is exploited to discriminate the single top quark signal from the comparatively large backgrounds. We measure a single top production cross section ofmore » $$3.04^{+0.57}_{-0.53} (\\mathrm{stat.~+~syst.})$$ pb assuming $$m_{\\rm top}=172.5$$~GeV/$c^2$. In addition, we extract the CKM matrix element value $$|V_{tb}|=0.96\\pm 0.09~(\\mathrm{stat.~+~syst.})\\ ± 0.05~(\\mathrm{theory})$$ and set a lower limit of $$|V_{tb}|>0.78$$ at the 95% credibility level.« less

  18. Measurements of the top-quark mass and the tt cross section in the hadronic τ+jets decay channel at sqrt[s] = 1.96 TeV.

    PubMed

    Aaltonen, T; Álvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Bae, T; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Bisello, D; Bizjak, I; Bland, K R; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brigliadori, L; Bromberg, C; Brucken, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Calamba, A; Calancha, C; Camarda, S; Campanelli, M; Campbell, M; Canelli, F; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chung, W H; Chung, Y S; Ciocci, M A; Clark, A; Clarke, C; Compostella, G; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Crescioli, F; Cuevas, J; Culbertson, R; Dagenhart, D; d'Ascenzo, N; Datta, M; de Barbaro, P; Dell'orso, M; Demortier, L; Deninno, M; Devoto, F; d'Errico, M; Di Canto, A; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Dorigo, M; Dorigo, T; Ebina, K; Elagin, A; Eppig, A; Erbacher, R; Errede, S; Ershaidat, N; Eusebi, R; Farrington, S; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Funakoshi, Y; Furic, I; Gallinaro, M; Garcia, J E; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Grinstein, S; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Hahn, S R; Halkiadakis, E; Hamaguchi, A; Han, J Y; Happacher, F; Hara, K; Hare, D; Hare, M; Harr, R F; Hatakeyama, K; Hays, C; Heck, M; Heinrich, J; Herndon, M; Hewamanage, S; Hocker, A; Hopkins, W; Horn, D; Hou, S; Hughes, R E; Hurwitz, M; Husemann, U; Hussain, N; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kamon, T; Karchin, P E; Kasmi, A; Kato, Y; Ketchum, W; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kim, Y J; Kimura, N; Kirby, M; Klimenko, S; Knoepfel, K; Kondo, K; Kong, D J; Konigsberg, J; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Kruse, M; Krutelyov, V; Kuhr, T; Kurata, M; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lecompte, T; Lee, E; Lee, H S; Lee, J S; Lee, S W; Leo, S; Leone, S; Lewis, J D; Limosani, A; Lin, C-J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, H; Liu, Q; Liu, T; Lockwitz, S; Loginov, A; Lucchesi, D; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maeshima, K; Maestro, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Martínez, M; Mastrandrea, P; Matera, K; Mattson, M E; Mazzacane, A; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Mondragon, M N; Moon, C S; Moore, R; Morello, M J; Morlock, J; Movilla Fernandez, P; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Noh, S Y; Norniella, O; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Poprocki, S; Potamianos, K; Prokoshin, F; Pranko, A; Ptohos, F; Punzi, G; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Renton, P; Rescigno, M; Riddick, T; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Safonov, A; Sakumoto, W K; Sakurai, Y; Santi, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, A; Schmidt, E E; Schwarz, T; Scodellaro, L; Scribano, A; Scuri, F; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shochet, M; Shreyber-Tecker, I; Simonenko, A; Sinervo, P; Sliwa, K; Smith, J R; Snider, F D; Soha, A; Sorin, V; Song, H; Squillacioti, P; Stancari, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Strycker, G L; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thome, J; Thompson, G A; Thomson, E; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Ukegawa, F; Uozumi, S; Varganov, A; Vázquez, F; Velev, G; Vellidis, C; Vidal, M; Vila, I; Vilar, R; Vizán, J; Vogel, M; Volpi, G; Wagner, P; Wagner, R L; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Wester, W C; Whiteson, D; Wicklund, A B; Wicklund, E; Wilbur, S; Wick, F; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamato, D; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanetti, A; Zeng, Y; Zhou, C; Zucchelli, S

    2012-11-09

    We present the first direct measurement of the top-quark mass using tt events decaying in the hadronic τ+jets decay channel. Using data corresponding to an integrated luminosity of 2.2 fb(-1) collected by the CDF II detector in pp collisions at sqrt[s] = 1.96 TeV at the Fermilab Tevatron, we measure the tt cross section, σ(tt), and the top-quark mass, M(top). We extract M(top) from a likelihood based on per-event probabilities calculated with leading-order signal and background matrix elements. We measure σ(tt) = 8.8 ± 3.3(stat) ± 2.2(syst) pb and M(top) = 172.7 ± 9.3(stat) ± 3.7(syst) GeV/c(2).

  19. Biophysical Neural Spiking, Bursting, and Excitability Dynamics in Reconfigurable Analog VLSI.

    PubMed

    Yu, T; Sejnowski, T J; Cauwenberghs, G

    2011-10-01

    We study a range of neural dynamics under variations in biophysical parameters underlying extended Morris-Lecar and Hodgkin-Huxley models in three gating variables. The extended models are implemented in NeuroDyn, a four neuron, twelve synapse continuous-time analog VLSI programmable neural emulation platform with generalized channel kinetics and biophysical membrane dynamics. The dynamics exhibit a wide range of time scales extending beyond 100 ms neglected in typical silicon models of tonic spiking neurons. Circuit simulations and measurements show transition from tonic spiking to tonic bursting dynamics through variation of a single conductance parameter governing calcium recovery. We similarly demonstrate transition from graded to all-or-none neural excitability in the onset of spiking dynamics through the variation of channel kinetic parameters governing the speed of potassium activation. Other combinations of variations in conductance and channel kinetic parameters give rise to phasic spiking and spike frequency adaptation dynamics. The NeuroDyn chip consumes 1.29 mW and occupies 3 mm × 3 mm in 0.5 μm CMOS, supporting emerging developments in neuromorphic silicon-neuron interfaces.

  20. Neuroadhesive L1 coating attenuates acute microglial attachment to neural electrodes as revealed by live two-photon microscopy.

    PubMed

    Eles, James R; Vazquez, Alberto L; Snyder, Noah R; Lagenaur, Carl; Murphy, Matthew C; Kozai, Takashi D Y; Cui, X Tracy

    2017-01-01

    Implantable neural electrode technologies for chronic neural recordings can restore functional control to paralysis and limb loss victims through brain-machine interfaces. These probes, however, have high failure rates partly due to the biological responses to the probe which generate an inflammatory scar and subsequent neuronal cell death. L1 is a neuronal specific cell adhesion molecule and has been shown to minimize glial scar formation and promote electrode-neuron integration when covalently attached to the surface of neural probes. In this work, the acute microglial response to L1-coated neural probes was evaluated in vivo by implanting coated devices into the cortex of mice with fluorescently labeled microglia, and tracking microglial dynamics with multi-photon microscopy for the ensuing 6 h in order to understand L1's cellular mechanisms of action. Microglia became activated immediately after implantation, extending processes towards both L1-coated and uncoated control probes at similar velocities. After the processes made contact with the probes, microglial processes expanded to cover 47.7% of the control probes' surfaces. For L1-coated probes, however, there was a statistically significant 83% reduction in microglial surface coverage. This effect was sustained through the experiment. At 6 h post-implant, the radius of microglia activation was reduced for the L1 probes by 20%, shifting from 130.0 to 103.5 μm with the coating. Microglia as far as 270 μm from the implant site displayed significantly lower morphological characteristics of activation for the L1 group. These results suggest that the L1 surface treatment works in an acute setting by microglial mediated mechanisms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Optogenetic stimulation of multiwell MEA plates for neural and cardiac applications

    NASA Astrophysics Data System (ADS)

    Clements, Isaac P.; Millard, Daniel C.; Nicolini, Anthony M.; Preyer, Amanda J.; Grier, Robert; Heckerling, Andrew; Blum, Richard A.; Tyler, Phillip; McSweeney, K. M.; Lu, Yi-Fan; Hall, Diana; Ross, James D.

    2016-03-01

    Microelectrode array (MEA) technology enables advanced drug screening and "disease-in-a-dish" modeling by measuring the electrical activity of cultured networks of neural or cardiac cells. Recent developments in human stem cell technologies, advancements in genetic models, and regulatory initiatives for drug screening have increased the demand for MEA-based assays. In response, Axion Biosystems previously developed a multiwell MEA platform, providing up to 96 MEA culture wells arrayed into a standard microplate format. Multiwell MEA-based assays would be further enhanced by optogenetic stimulation, which enables selective excitation and inhibition of targeted cell types. This capability for selective control over cell culture states would allow finer pacing and probing of cell networks for more reliable and complete characterization of complex network dynamics. Here we describe a system for independent optogenetic stimulation of each well of a 48-well MEA plate. The system enables finely graded control of light delivery during simultaneous recording of network activity in each well. Using human induced pluripotent stem cell (hiPSC) derived cardiomyocytes and rodent primary neuronal cultures, we demonstrate high channel-count light-based excitation and suppression in several proof-of-concept experimental models. Our findings demonstrate advantages of combining multiwell optical stimulation and MEA recording for applications including cardiac safety screening, neural toxicity assessment, and advanced characterization of complex neuronal diseases.

  2. Selecting electrode configurations for image-guided cochlear implant programming using template matching.

    PubMed

    Zhang, Dongqing; Zhao, Yiyuan; Noble, Jack H; Dawant, Benoit M

    2018-04-01

    Cochlear implants (CIs) are neural prostheses that restore hearing using an electrode array implanted in the cochlea. After implantation, the CI processor is programmed by an audiologist. One factor that negatively impacts outcomes and can be addressed by programming is cross-electrode neural stimulation overlap (NSO). We have proposed a system to assist the audiologist in programming the CI that we call image-guided CI programming (IGCIP). IGCIP permits using CT images to detect NSO and recommend deactivation of a subset of electrodes to avoid NSO. We have shown that IGCIP significantly improves hearing outcomes. Most of the IGCIP steps are robustly automated but electrode configuration selection still sometimes requires manual intervention. With expertise, distance-versus-frequency curves, which are a way to visualize the spatial relationship learned from CT between the electrodes and the nerves they stimulate, can be used to select the electrode configuration. We propose an automated technique for electrode configuration selection. A comparison between this approach and one we have previously proposed shows that our method produces results that are as good as those obtained with our previous method while being generic and requiring fewer parameters.

  3. Conduction Abnormalities and Pacemaker Implantations After SAPIEN 3 Vs SAPIEN XT Prosthesis Aortic Valve Implantation.

    PubMed

    Husser, Oliver; Kessler, Thorsten; Burgdorf, Christof; Templin, Christian; Pellegrini, Costanza; Schneider, Simon; Kasel, Albert Markus; Kastrati, Adnan; Schunkert, Heribert; Hengstenberg, Christian

    2016-02-01

    Transcatheter aortic valve implantation is increasingly used in patients with aortic stenosis. Post-procedural intraventricular conduction abnormalities and permanent pacemaker implantations remain a serious concern. Recently, the Edwards SAPIEN 3 prosthesis has replaced the SAPIEN XT. We sought to determine the incidences of new-onset intraventricular conduction abnormalities and permanent pacemaker implantations by comparing the 2 devices. We analyzed the last consecutive 103 patients undergoing transcatheter aortic valve implantation with SAPIEN XT before SAPIEN 3 was used in the next 105 patients. To analyze permanent pacemaker implantations and new-onset intraventricular conduction abnormalities, patients with these conditions at baseline were excluded. Electrocardiograms were recorded at baseline, after the procedure, and before discharge. SAPIEN 3 was associated with higher device success (100% vs 92%; P=.005) and less paravalvular leakage (0% vs 7%; P<.001). The incidence of permanent pacemaker implantations was 12.6% (23 of 183) with no difference between the 2 groups (SAPIEN 3: 12.5% [12 of 96] vs SAPIEN XT: 12.6% [11 of 87]; P=.99). SAPIEN 3 was associated with a higher rate of new-onset intraventricular conduction abnormalities (49% vs 27%; P=.007) due to a higher rate of fascicular blocks (17% vs 5%; P=.021). There was no statistically significant difference in transient (29% [20 of 69] vs persistent 19% [12 of 64]; P=.168) left bundle branch blocks (28% [19 of 69] vs 17% [11 of 64]; P=.154) when SAPIEN 3 was compared with SAPIEN XT. We found a trend toward a higher rate of new-onset intraventricular conduction abnormalities with SAPIEN 3 compared with SAPIEN XT, although this did not result in a higher permanent pacemaker implantation rate. Copyright © 2015 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  4. Clinical outcomes of implant therapy in ectodermal dysplasia patients: a systematic review.

    PubMed

    Wang, Y; He, J; Decker, A M; Hu, J C; Zou, D

    2016-08-01

    The purpose of this review was to determine the outcome of oral function reconstruction in ectodermal dysplasia (ED) patients who have received dental implant therapy. A search was made of the PubMed and Web of Science databases; key words used were "(ectodermal dysplasia) AND (implant OR implants)", with supplementary retrieval key words "dental implant", "zygomatic implant", "anodontia", and "edentulous". Patient age, use of bone graft, implant site, type of implant, and survival rate of the implants were included in the subsequent data analysis. Forty-five articles published between 1988 and October 2015 were included in this analysis. The cases of a total of 96 patients were retrieved (22 children and 74 adults); these patients received a total of 701 implants. Fourteen implants were removed during a median follow-up time of 24 months. The 24-month implant survival rate was 97.9% in adult subjects and 98.6% in children. Sixty-eight percent of adult patients underwent bone augmentation prior to implant placement. Based on this review, dental implants are commonly used in the oral reconstruction of ED patients. However, long-term data on bone augmentation and implant success are needed, as well as additional clinical evidence on bone resorption, the esthetic outcomes of implant therapy, and physiological considerations in ED patients. Copyright © 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  5. Embedded System for Prosthetic Control Using Implanted Neuromuscular Interfaces Accessed Via an Osseointegrated Implant.

    PubMed

    Mastinu, Enzo; Doguet, Pascal; Botquin, Yohan; Hakansson, Bo; Ortiz-Catalan, Max

    2017-08-01

    Despite the technological progress in robotics achieved in the last decades, prosthetic limbs still lack functionality, reliability, and comfort. Recently, an implanted neuromusculoskeletal interface built upon osseointegration was developed and tested in humans, namely the Osseointegrated Human-Machine Gateway. Here, we present an embedded system to exploit the advantages of this technology. Our artificial limb controller allows for bioelectric signals acquisition, processing, decoding of motor intent, prosthetic control, and sensory feedback. It includes a neurostimulator to provide direct neural feedback based on sensory information. The system was validated using real-time tasks characterization, power consumption evaluation, and myoelectric pattern recognition performance. Functionality was proven in a first pilot patient from whom results of daily usage were obtained. The system was designed to be reliably used in activities of daily living, as well as a research platform to monitor prosthesis usage and training, machine-learning-based control algorithms, and neural stimulation paradigms.

  6. Estimation of neural energy in microelectrode signals

    NASA Astrophysics Data System (ADS)

    Gaumond, R. P.; Clement, R.; Silva, R.; Sander, D.

    2004-09-01

    We considered the problem of determining the neural contribution to the signal recorded by an intracortical electrode. We developed a linear least-squares approach to determine the energy fraction of a signal attributable to an arbitrary number of autocorrelation-defined signals buried in noise. Application of the method requires estimation of autocorrelation functions Rap(tgr) characterizing the action potential (AP) waveforms and Rn(tgr) characterizing background noise. This method was applied to the analysis of chronically implanted microelectrode signals from motor cortex of rat. We found that neural (AP) energy consisted of a large-signal component which grows linearly with the number of threshold-detected neural events and a small-signal component unrelated to the count of threshold-detected AP signals. The addition of pseudorandom noise to electrode signals demonstrated the algorithm's effectiveness for a wide range of noise-to-signal energy ratios (0.08 to 39). We suggest, therefore, that the method could be of use in providing a measure of neural response in situations where clearly identified spike waveforms cannot be isolated, or in providing an additional 'background' measure of microelectrode neural activity to supplement the traditional AP spike count.

  7. AutoNR: an automated system that measures ECAP thresholds with the Nucleus Freedom cochlear implant via machine intelligence.

    PubMed

    Botros, Andrew; van Dijk, Bas; Killian, Matthijs

    2007-05-01

    AutoNRT is an automated system that measures electrically evoked compound action potential (ECAP) thresholds from the auditory nerve with the Nucleus Freedom cochlear implant. ECAP thresholds along the electrode array are useful in objectively fitting cochlear implant systems for individual use. This paper provides the first detailed description of the AutoNRT algorithm and its expert systems, and reports the clinical success of AutoNRT to date. AutoNRT determines thresholds by visual detection, using two decision tree expert systems that automatically recognise ECAPs. The expert systems are guided by a dataset of 5393 neural response measurements. The algorithm approaches threshold from lower stimulus levels, ensuring recipient safety during postoperative measurements. Intraoperative measurements use the same algorithm but proceed faster by beginning at stimulus levels much closer to threshold. When searching for ECAPs, AutoNRT uses a highly specific expert system (specificity of 99% during training, 96% during testing; sensitivity of 91% during training, 89% during testing). Once ECAPs are established, AutoNRT uses an unbiased expert system to determine an accurate threshold. Throughout the execution of the algorithm, recording parameters (such as implant amplifier gain) are automatically optimised when needed. In a study that included 29 intraoperative and 29 postoperative subjects (a total of 418 electrodes), AutoNRT determined a threshold in 93% of cases where a human expert also determined a threshold. When compared to the median threshold of multiple human observers on 77 randomly selected electrodes, AutoNRT performed as accurately as the 'average' clinician. AutoNRT has demonstrated a high success rate and a level of performance that is comparable with human experts. It has been used in many clinics worldwide throughout the clinical trial and commercial launch of Nucleus Custom Sound Suite, significantly streamlining the clinical procedures associated with

  8. Possible sources of neuroprotection following subretinal silicon chip implantation in RCS rats

    NASA Astrophysics Data System (ADS)

    Pardue, Machelle T.; Phillips, Michael J.; Yin, Hang; Fernandes, Alcides; Cheng, Yian; Chow, Alan Y.; Ball, Sherry L.

    2005-03-01

    Current retinal prosthetics are designed to stimulate existing neural circuits in diseased retinas to create a visual signal. However, implantation of retinal prosthetics may create a neurotrophic environment that also leads to improvements in visual function. Possible sources of increased neuroprotective effects on the retina may arise from electrical activity generated by the prosthetic, mechanical injury due to surgical implantation, and/or presence of a chronic foreign body. This study evaluates these three neuroprotective sources by implanting Royal College of Surgeons (RCS) rats, a model of retinitis pigmentosa, with a subretinal implant at an early stage of photoreceptor degeneration. Treatment groups included rats implanted with active and inactive devices, as well as sham-operated. These groups were compared to unoperated controls. Evaluation of retinal function throughout an 18 week post-implantation period demonstrated transient functional improvements in eyes implanted with an inactive device at 6, 12 and 14 weeks post-implantation. However, the number of photoreceptors located directly over or around the implant or sham incision was significantly increased in eyes implanted with an active or inactive device or sham-operated. These results indicate that in the RCS rat localized neuroprotection of photoreceptors from mechanical injury or a chronic foreign body may provide similar results to subretinal electrical stimulation at the current output evaluated here.

  9. Monitoring the evolution of boron doped porous diamond electrode on flexible retinal implant by OCT and in vivo impedance spectroscopy.

    PubMed

    Hébert, Clément; Cottance, Myline; Degardin, Julie; Scorsone, Emmanuel; Rousseau, Lionel; Lissorgues, Gaelle; Bergonzo, Philippe; Picaud, Serge

    2016-12-01

    Nanocrystalline Boron doped Diamond proved to be a very attractive material for neural interfacing, especially with the retina, where reduce glia growth is observed with respect to other materials, thus facilitating neuro-stimulation over long terms. In the present study, we integrated diamond microelectrodes on a polyimide substrate and investigated their performances for the development of neural prosthesis. A full description of the microfabrication of the implants is provided and their functionalities are assessed using cyclic voltammetry and electrochemical impedance spectroscopy. A porous structure of the electrode surface was thus revealed and showed promising properties for neural recording or stimulation. Using the flexible implant, we showed that is possible to follow in vivo the evolution of the electric contact between the diamond electrodes and the retina over 4months by using electrochemical impedance spectroscopy. The position of the implant was also monitored by optical coherence tomography to corroborate the information given by the impedance measurements. The results suggest that diamond microelectrodes are very good candidates for retinal prosthesis. Copyright © 2016. Published by Elsevier B.V.

  10. Self-organization of helium precipitates into elongated channels within metal nanolayers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Di; Li, Nan; Yuryev, Dina

    Material degradation due to precipitation of implanted helium (He) is a key concern in nuclear energy. Decades of research have mapped out the fate of He precipitates in metals, from nucleation and growth of equiaxed bubbles and voids to formation and bursting of surface blisters. By contrast, we show that He precipitates confined within nanoscale metal layers depart from their classical growth trajectories: They self-organize into elongated channels. These channels form via templated nucleation of He precipitates along layer surfaces followed by their growth and spontaneous coalescence into stable precipitate lines. The total line length and connectivity increases with themore » amount of implanted He, indicating that these channels ultimately interconnect into percolating “vascular” networks. In conclusion, vascularized metal composites promise a transformative solution to He-induced damage by enabling in operando outgassing of He and other impurities while maintaining material integrity.« less

  11. Self-organization of helium precipitates into elongated channels within metal nanolayers

    DOE PAGES

    Chen, Di; Li, Nan; Yuryev, Dina; ...

    2017-11-10

    Material degradation due to precipitation of implanted helium (He) is a key concern in nuclear energy. Decades of research have mapped out the fate of He precipitates in metals, from nucleation and growth of equiaxed bubbles and voids to formation and bursting of surface blisters. By contrast, we show that He precipitates confined within nanoscale metal layers depart from their classical growth trajectories: They self-organize into elongated channels. These channels form via templated nucleation of He precipitates along layer surfaces followed by their growth and spontaneous coalescence into stable precipitate lines. The total line length and connectivity increases with themore » amount of implanted He, indicating that these channels ultimately interconnect into percolating “vascular” networks. In conclusion, vascularized metal composites promise a transformative solution to He-induced damage by enabling in operando outgassing of He and other impurities while maintaining material integrity.« less

  12. Connections matter: channeled hydrogels to improve vascularization.

    PubMed

    Muehleder, Severin; Ovsianikov, Aleksandr; Zipperle, Johannes; Redl, Heinz; Holnthoner, Wolfgang

    2014-01-01

    The use of cell-laden hydrogels to engineer soft tissue has been emerging within the past years. Despite, several newly developed and sophisticated techniques to encapsulate different cell types the importance of vascularization of the engineered constructs is often underestimated. As a result, cell death within a construct leads to impaired function and inclusion of the implant. Here, we discuss the fabrication of hollow channels within hydrogels as a promising strategy to facilitate vascularization. Furthermore, we present an overview on the feasible use of removable spacers, 3D laser-, and planar processing strategies to create channels within hydrogels. The implementation of these structures promotes control over cell distribution and increases oxygen transport and nutrient supply in vitro. However, many studies lack the use of endothelial cells in their approaches leaving out an important factor to enhance vessel ingrowth and anastomosis formation upon implantation. In addition, the adequate endothelial cell type needs to be considered to make these approaches bridge the gap to in vivo applications.

  13. Microfluidic Actuation of Carbon Nanotube Fibers for Neural Recordings

    NASA Astrophysics Data System (ADS)

    Vercosa, Daniel G.

    Implantable devices to record and stimulate neural circuits have led to breakthroughs in neuroscience; however, technologies capable of electrical recording at the cellular level typically rely on rigid metals that poorly match the mechanical properties of soft brain tissue. As a result these electrodes often cause extensive acute and chronic injury, leading to short electrode lifetime. Recently, flexible electrodes such as Carbon Nanotube fibers (CNTf) have emerged as an attractive alternative to conventional electrodes and studies have shown that these flexible electrodes reduce neuro-inflammation and increase the quality and longevity of neural recordings. Insertion of these new compliant electrodes, however, remains challenge. The stiffening agents necessary to make the electrodes rigid enough to be inserted increases device footprint, which exacerbates brain damage during implantation. To overcome this challenge we have developed a novel technology to precisely implant and actuate high-performance, flexible carbon nanotube fiber (CNTf) microelectrodes without using a stiffening agents or shuttles. Instead, our technology uses drag forces within a microfluidic device to drive electrodes into tissue while minimizing the amount of fluid that is ejected into the tissue. In vitro experiments in brain phantoms, show that microfluidic actuated CNTf can be implanted at least 4.5 mm depth with 30 microm precision, while keeping the total volume of fluid ejected below 0.1 microL. As proof of concept, we inserted CNTfs in the small cnidarian Hydra littoralis and observed compound action potentials corresponding to contractions and in agreement with the literature. Additionally, brain slices extracted from transgenic mice were used to show that our device can be used to record spontaneous and light evoked activity from the cortex and deep brain regions such as the thalamic reticular nucleus (TRN). Overall our microfluidic actuation technology provides a platform for

  14. A comparison of Staphylococcus aureus biofilm formation on cobalt-chrome and titanium-alloy spinal implants.

    PubMed

    Patel, Shalin S; Aruni, Wilson; Inceoglu, Serkan; Akpolat, Yusuf T; Botimer, Gary D; Cheng, Wayne K; Danisa, Olumide A

    2016-09-01

    The use of cobalt chrome (CoCr) implants in spinal surgery has become increasingly popular. However, there have been no studies specifically comparing biofilm formation on CoCr with that of titanium-alloy spinal implants. The objective of this study was to compare the difference in propensity for biofilm formation between these two materials, as it specifically relates to spinal rods. Staphylococcus aureus subsp. Aureus (ATCC 6538) were incubated with two different types of spinal rods composed of either CoCr or titanium-alloy. The spinal rods were then subject to a trypsin wash to allow for isolation of the colonized organism and associated biofilms. The associated optical density values (OD) from the bacterial isolates were obtained and the bacterial solutions were plated on brain-heart infusion agar plates and the resultant colony-forming units (CFU) were counted. The OD values for the titanium-alloy rods were 1.105±0.096nm (mean±SD) and 1.040±0.026nm at 48hours and 96hours, respectively. In contrast, the OD values for the CoCr rods were 1.332±0.161nm and 1.115±0.207nm at 48 and 96hours, respectively (p<0.05). The CFU values were 1481±417/100mm(2) and 745±159/100mm(2) at 48 and 96hours, respectively for the titanium-alloy group. These values were significantly lower than the CFU values obtained from the CoCr group which were 2721±605/100mm(2) and 928±88/100mm(2) (p<0.001) at both 48 and 96hours respectively. Our findings, evaluating both the OD and CFU values, indicate that implants composed of CoCr had a higher proclivity towards biofilm formation compared to titanium-alloy implants. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Flow and heat transfer in a curved channel

    NASA Technical Reports Server (NTRS)

    Brinich, P. F.; Graham, R. W.

    1977-01-01

    Flow and heat transfer in a curved channel of aspect ratio 6 and inner- to outer-wall radius ratio 0.96 were studied. Secondary currents and large longitudinal vortices were found. The heat-transfer rates of the outer and inner walls were independently controlled to maintain a constant wall temperature. Heating the inner wall increased the pressure drop along the channel length, whereas heating the outer wall had little effect. Outer-wall heat transfer was as much as 40 percent greater than the straight-channel correlation, and inner-wall heat transfer was 22 percent greater than the straight-channel correlation.

  16. Modulation Depth Estimation and Variable Selection in State-Space Models for Neural Interfaces

    PubMed Central

    Hochberg, Leigh R.; Donoghue, John P.; Brown, Emery N.

    2015-01-01

    Rapid developments in neural interface technology are making it possible to record increasingly large signal sets of neural activity. Various factors such as asymmetrical information distribution and across-channel redundancy may, however, limit the benefit of high-dimensional signal sets, and the increased computational complexity may not yield corresponding improvement in system performance. High-dimensional system models may also lead to overfitting and lack of generalizability. To address these issues, we present a generalized modulation depth measure using the state-space framework that quantifies the tuning of a neural signal channel to relevant behavioral covariates. For a dynamical system, we develop computationally efficient procedures for estimating modulation depth from multivariate data. We show that this measure can be used to rank neural signals and select an optimal channel subset for inclusion in the neural decoding algorithm. We present a scheme for choosing the optimal subset based on model order selection criteria. We apply this method to neuronal ensemble spike-rate decoding in neural interfaces, using our framework to relate motor cortical activity with intended movement kinematics. With offline analysis of intracortical motor imagery data obtained from individuals with tetraplegia using the BrainGate neural interface, we demonstrate that our variable selection scheme is useful for identifying and ranking the most information-rich neural signals. We demonstrate that our approach offers several orders of magnitude lower complexity but virtually identical decoding performance compared to greedy search and other selection schemes. Our statistical analysis shows that the modulation depth of human motor cortical single-unit signals is well characterized by the generalized Pareto distribution. Our variable selection scheme has wide applicability in problems involving multisensor signal modeling and estimation in biomedical engineering systems. PMID

  17. Improving Neural Recording Technology at the Nanoscale

    NASA Astrophysics Data System (ADS)

    Ferguson, John Eric

    Neural recording electrodes are widely used to study normal brain function (e.g., learning, memory, and sensation) and abnormal brain function (e.g., epilepsy, addiction, and depression) and to interface with the nervous system for neuroprosthetics. With a deep understanding of the electrode interface at the nanoscale and the use of novel nanofabrication processes, neural recording electrodes can be designed that surpass previous limits and enable new applications. In this thesis, I will discuss three projects. In the first project, we created an ultralow-impedance electrode coating by controlling the nanoscale texture of electrode surfaces. In the second project, we developed a novel nanowire electrode for long-term intracellular recordings. In the third project, we created a means of wirelessly communicating with ultra-miniature, implantable neural recording devices. The techniques developed for these projects offer significant improvements in the quality of neural recordings. They can also open the door to new types of experiments and medical devices, which can lead to a better understanding of the brain and can enable novel and improved tools for clinical applications.

  18. Ultrafine-grained titanium for medical implants

    DOEpatents

    Zhu, Yuntian T.; Lowe, Terry C.; Valiev, Ruslan Z.; Stolyarov, Vladimir V.; Latysh, Vladimir V.; Raab, Georgy J.

    2002-01-01

    We disclose ultrafine-grained titanium. A coarse-grained titanium billet is subjected to multiple extrusions through a preheated equal channel angular extrusion (ECAE) die, with billet rotation between subsequent extrusions. The resulting billet is cold processed by cold rolling and/or cold extrusion, with optional annealing. The resulting ultrafine-grained titanium has greatly improved mechanical properties and is used to make medical implants.

  19. Auditory responses to electric and infrared neural stimulation of the rat cochlear nucleus.

    PubMed

    Verma, Rohit U; Guex, Amélie A; Hancock, Kenneth E; Durakovic, Nedim; McKay, Colette M; Slama, Michaël C C; Brown, M Christian; Lee, Daniel J

    2014-04-01

    In an effort to improve the auditory brainstem implant, a prosthesis in which user outcomes are modest, we applied electric and infrared neural stimulation (INS) to the cochlear nucleus in a rat animal model. Electric stimulation evoked regions of neural activation in the inferior colliculus and short-latency, multipeaked auditory brainstem responses (ABRs). Pulsed INS, delivered to the surface of the cochlear nucleus via an optical fiber, evoked broad neural activation in the inferior colliculus. Strongest responses were recorded when the fiber was placed at lateral positions on the cochlear nucleus, close to the temporal bone. INS-evoked ABRs were multipeaked but longer in latency than those for electric stimulation; they resembled the responses to acoustic stimulation. After deafening, responses to electric stimulation persisted, whereas those to INS disappeared, consistent with a reported "optophonic" effect, a laser-induced acoustic artifact. Thus, for deaf individuals who use the auditory brainstem implant, INS alone did not appear promising as a new approach. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. General form of genuine multipartite entanglement quantum channels for teleportation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen Pingxing; Key Laboratory of Quantum Communication and Quantum Computation, University of Science and Technology of China, Hefei 230026; Department of Physics, National University of Defense Technology, Changsha 410073

    2006-09-15

    Recently Yeo and Chua [Phys. Rev. Lett. 96, 060502 (2006)] presented an explicit protocol for faithfully teleporting an arbitrary two-qubit state via a genuine four-qubit entanglement channel. Here we generalize completely their results to teleporting an arbitrary N-qubit state via genuine N-qubit entanglement channels. And we present the general form of the genuine multipartite entanglement channels, namely, the sufficient and necessary condition the genuine N-qubit entanglement channels must satisfy to teleport an arbitrary N-qubit state.

  1. Design and Evaluation of a Cochlear Implant Strategy Based on a “Phantom” Channel

    PubMed Central

    Nogueira, Waldo; Litvak, Leonid M.; Saoji, Aniket A.; Büchner, Andreas

    2015-01-01

    Unbalanced bipolar stimulation, delivered using charge balanced pulses, was used to produce “Phantom stimulation”, stimulation beyond the most apical contact of a cochlear implant’s electrode array. The Phantom channel was allocated audio frequencies below 300Hz in a speech coding strategy, conveying energy some two octaves lower than the clinical strategy and hence delivering the fundamental frequency of speech and of many musical tones. A group of 12 Advanced Bionics cochlear implant recipients took part in a chronic study investigating the fitting of the Phantom strategy and speech and music perception when using Phantom. The evaluation of speech in noise was performed immediately after fitting Phantom for the first time (Session 1) and after one month of take-home experience (Session 2). A repeated measures of analysis of variance (ANOVA) within factors strategy (Clinical, Phantom) and interaction time (Session 1, Session 2) revealed a significant effect for the interaction time and strategy. Phantom obtained a significant improvement in speech intelligibility after one month of use. Furthermore, a trend towards a better performance with Phantom (48%) with respect to F120 (37%) after 1 month of use failed to reach significance after type 1 error correction. Questionnaire results show a preference for Phantom when listening to music, likely driven by an improved balance between high and low frequencies. PMID:25806818

  2. The early days of the multi channel cochlear implant: efforts and achievement in France.

    PubMed

    Chouard, C H

    2015-04-01

    On September 10th 2013, the clinical medical research Lasker award winners were rewarded for their work on multichannel cochlear implant. It has been my pleasure to see that such a major topic had caught the attention of the Members of the Jury for this prestigious award. That is why I accepted an invitation to participate in a special issue of Hearing Research devoted to the three winners. Here I highlight four scientific contributions made by the French team in late 1970s and early 1980s to modern multichannel cochlear implant development. 1) Chouard and MacLeod plotted an approximate frequency map of the whole length of the human cochlea, including its "hidden face" corresponding to speech frequencies. Moreover MacLeod suggested a sequential display of electrical stimulation as a function of each electrode, a precursor to today's electrodogram and interleaved stimulation. 2) Chouard performed total cochlear implantation in a deaf adult male with 8 electrically independent electrodes that were evenly distributed along the cochlea. 3) Chouard and MacLeod described in a patent detailed sound signal processing for a functional multichannel cochlear implant and reported speech discrimination without help of lip reading in some totally deafened patients. 4) Chouard experimentally demonstrated in the guinea pig the advantage of early cochlear implantation in treating profound neonatal deafness. This article is part of a Special Issue entitled . Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Epidemiology and risk factors of peri-implantitis: A systematic review.

    PubMed

    Dreyer, H; Grischke, J; Tiede, C; Eberhard, J; Schweitzer, A; Toikkanen, S E; Glöckner, S; Krause, G; Stiesch, M

    2018-06-07

    The purpose of this systematic review and meta-analysis was to assess the prevalence, incidence and risk factors of peri-implantitis in the current literature. An electronic search was performed to identify publications from January 1980 until March 2016 on 9 databases. The prevalence and incidence of peri-implantitis were assessed in different subgroups of patients and the prevalences were adjusted for sample size (SSA) of studies. For 12 of 111 identified putative risk factors and risk indicators, forest plots were created. Heterogeneity analysis and random effect meta-analysis were performed for selected potential risk factors of peri-implantitis. The search retrieved 8357 potentially relevant studies. Fifty-seven studies were included in the systematic review. Overall, the prevalence of peri-implantitis on implant level ranged from 1.1% to 85.0% and the incidence from 0.4% within 3 years, to 43.9% within 5 years, respectively. The median prevalence of peri-implantitis was 9.0% (SSA 10.9%) for regular participants of a prophylaxis program, 18.8% (SSA 8.8%) for patients without regular preventive maintenance, 11.0% (SSA 7.4%) for non-smokers, 7.0% (SSA 7.0%) among patients representing the general population, 9.6% (SSA 9.6%) for patients provided with fixed partial dentures, 14.3% (SSA 9.8%) for subjects with a history of periodontitis, 26.0% (SSA 28.8%) for patients with implant function time ≥5 years and 21.2% (SSA 38.4%) for ≥10 years. On a medium and medium-high level of evidence, smoking (effect summary OR 1.7, 95% CI 1.25-2.3), diabetes mellitus (effect summary OR 2.5; 95% CI 1.4-4.5), lack of prophylaxis and history or presence of periodontitis were identified as risk factors of peri-implantitis. There is medium-high evidence that patient's age (effect summary OR 1.0, 95% CI 0.87-1.16), gender and maxillary implants are not related to peri-implantitis. Currently, there is no convincing or low evidence available that identifies osteoporosis, absence

  4. Genetic algorithm applied to the selection of factors in principal component-artificial neural networks: application to QSAR study of calcium channel antagonist activity of 1,4-dihydropyridines (nifedipine analogous).

    PubMed

    Hemmateenejad, Bahram; Akhond, Morteza; Miri, Ramin; Shamsipur, Mojtaba

    2003-01-01

    A QSAR algorithm, principal component-genetic algorithm-artificial neural network (PC-GA-ANN), has been applied to a set of newly synthesized calcium channel blockers, which are of special interest because of their role in cardiac diseases. A data set of 124 1,4-dihydropyridines bearing different ester substituents at the C-3 and C-5 positions of the dihydropyridine ring and nitroimidazolyl, phenylimidazolyl, and methylsulfonylimidazolyl groups at the C-4 position with known Ca(2+) channel binding affinities was employed in this study. Ten different sets of descriptors (837 descriptors) were calculated for each molecule. The principal component analysis was used to compress the descriptor groups into principal components. The most significant descriptors of each set were selected and used as input for the ANN. The genetic algorithm (GA) was used for the selection of the best set of extracted principal components. A feed forward artificial neural network with a back-propagation of error algorithm was used to process the nonlinear relationship between the selected principal components and biological activity of the dihydropyridines. A comparison between PC-GA-ANN and routine PC-ANN shows that the first model yields better prediction ability.

  5. Hearing rehabilitation with a binaural cochlear implant in a patient with Erdheim-Chester disease.

    PubMed

    Querat, Charlotte; Thai-Van, Hung; Durand, Denis Vital; Cotton, François; Gallego, Stéphane; Truy, Eric

    2015-09-01

    Erdheim-Chester disease (ECD) is a rare non-Langerhans form of histiocytosis. This paper reports an exceptional case of bilateral neural involvement, responsible for profound hearing loss. Bilateral cochlear implantation was performed. We present a 57-year-old man affected by ECD with profound bilateral hearing loss. The patient underwent cochlear implantation with a binaural Digisonic(®) cochlear implant, 7 years after the initial diagnosis. Speech intelligibility rose to a plateau after about 6 months of cochlear implant use. The average outcome of speech intelligibility over time was 55% for dissyllabic words without lip reading, and 70% for sentences. Perception score decreased before the patient died from ECD. A description of the ECD and its otological manifestations is presented. This paper reports the effective hearing rehabilitation of profound bilateral hearing loss by the means of a binaural Digisonic(®) cochlear implant.

  6. Characteristics of early versus late implant failure: a retrospective study.

    PubMed

    Manor, Yifat; Oubaid, Saheer; Mardinger, Ofer; Chaushu, Gavriel; Nissan, Joseph

    2009-12-01

    Implant failures can be divided into early and late according to the timing of failure. The purpose of this study was to characterize and compare both types. A retrospective cohort study was conducted in 194 patients (98 men and 96 women) who presented after dental implant failures during a 6-year period (2000 to 2006). The patient served as the unit of analysis. A history of at least 1 failed and removed dental implant served as the inclusion criterion. Patients were excluded from this study whenever their files had missing data. The collected data included a patient's characteristics, failure characteristics, and the anatomic status of the alveolar ridge after failure. Late failures were associated with moderate to severe bone loss, a larger number of failed implants per patient, a higher incidence in men, and mostly in posterior areas. Early failures were associated with minimal bone loss, occurred more in women, at a younger age, and in most cases the implants were intended to support single crowns. Meticulous follow-up is needed to reveal and treat failing or ailing implants. Once established as hopeless, they should be removed as soon as possible to prevent further bone loss.

  7. Further studies on the effects of magnetic resonance imaging fields on middle ear implants.

    PubMed

    Applebaum, E L; Valvassori, G E

    1990-10-01

    We investigated the effects of magnetic resonance imaging (MRI) fields on 21 stapedectomy prostheses and other middle ear implants and two different receiver-stimulator modules from 22-channel cochlear implants. None of the middle ear implants was displaced by the magnetic field, except for one platinum-stainless steel stapedectomy piston. Magnetism was not induced in any of the middle ear implants subjected to prolonged exposure in the MRI scanner. We conclude that MRI could pose a hazard to patients who have had stapedectomy using certain platinum-stainless steel piston prostheses and to patients with cochlear implants. Magnetic resonance imaging should pose no hazard to patients who have had the other middle ear implants reported on in this and our previous investigation.

  8. Evaluation of focused multipolar stimulation for cochlear implants: a preclinical safety study

    NASA Astrophysics Data System (ADS)

    Shepherd, Robert K.; Wise, Andrew K.; Enke, Ya Lang; Carter, Paul M.; Fallon, James B.

    2017-08-01

    Objective. Cochlear implants (CIs) have a limited number of independent stimulation channels due to the highly conductive nature of the fluid-filled cochlea. Attempts to develop highly focused stimulation to improve speech perception in CI users includes the use of simultaneous stimulation via multiple current sources. Focused multipolar (FMP) stimulation is an example of this approach and has been shown to reduce interaction between stimulating channels. However, compared with conventional biphasic current pulses generated from a single current source, FMP is a complex stimulus that includes extended periods of stimulation before charge recovery is achieved, raising questions on whether chronic stimulation with this strategy is safe. The present study evaluated the long-term safety of intracochlear stimulation using FMP in a preclinical animal model of profound deafness. Approach. Six cats were bilaterally implanted with scala tympani electrode arrays two months after deafening, and received continuous unilateral FMP stimulation at levels that evoked a behavioural response for periods of up to 182 d. Electrode impedance, electrically-evoked compound action potentials (ECAPs) and auditory brainstem responses (EABRs) were monitored periodically over the course of the stimulation program from both the stimulated and contralateral control cochleae. On completion of the stimulation program cochleae were examined histologically and the electrode arrays were evaluated for evidence of platinum (Pt) corrosion. Main results. There was no significant difference in electrode impedance between control and chronically stimulated electrodes following long-term FMP stimulation. Moreover, there was no significant difference between ECAP and EABR thresholds evoked from control or stimulated cochleae at either the onset of stimulation or at completion of the stimulation program. Chronic FMP stimulation had no effect on spiral ganglion neuron (SGN) survival when compared with

  9. Encoding and decoding amplitude-modulated cochlear implant stimuli—a point process analysis

    PubMed Central

    Shea-Brown, Eric; Rubinstein, Jay T.

    2010-01-01

    Cochlear implant speech processors stimulate the auditory nerve by delivering amplitude-modulated electrical pulse trains to intracochlear electrodes. Studying how auditory nerve cells encode modulation information is of fundamental importance, therefore, to understanding cochlear implant function and improving speech perception in cochlear implant users. In this paper, we analyze simulated responses of the auditory nerve to amplitude-modulated cochlear implant stimuli using a point process model. First, we quantify the information encoded in the spike trains by testing an ideal observer’s ability to detect amplitude modulation in a two-alternative forced-choice task. We vary the amount of information available to the observer to probe how spike timing and averaged firing rate encode modulation. Second, we construct a neural decoding method that predicts several qualitative trends observed in psychophysical tests of amplitude modulation detection in cochlear implant listeners. We find that modulation information is primarily available in the sequence of spike times. The performance of an ideal observer, however, is inconsistent with observed trends in psychophysical data. Using a neural decoding method that jitters spike times to degrade its temporal resolution and then computes a common measure of phase locking from spike trains of a heterogeneous population of model nerve cells, we predict the correct qualitative dependence of modulation detection thresholds on modulation frequency and stimulus level. The decoder does not predict the observed loss of modulation sensitivity at high carrier pulse rates, but this framework can be applied to future models that better represent auditory nerve responses to high carrier pulse rate stimuli. The supplemental material of this article contains the article’s data in an active, re-usable format. PMID:20177761

  10. Quantized Synchronization of Chaotic Neural Networks With Scheduled Output Feedback Control.

    PubMed

    Wan, Ying; Cao, Jinde; Wen, Guanghui

    In this paper, the synchronization problem of master-slave chaotic neural networks with remote sensors, quantization process, and communication time delays is investigated. The information communication channel between the master chaotic neural network and slave chaotic neural network consists of several remote sensors, with each sensor able to access only partial knowledge of output information of the master neural network. At each sampling instants, each sensor updates its own measurement and only one sensor is scheduled to transmit its latest information to the controller's side in order to update the control inputs for the slave neural network. Thus, such communication process and control strategy are much more energy-saving comparing with the traditional point-to-point scheme. Sufficient conditions for output feedback control gain matrix, allowable length of sampling intervals, and upper bound of network-induced delays are derived to ensure the quantized synchronization of master-slave chaotic neural networks. Lastly, Chua's circuit system and 4-D Hopfield neural network are simulated to validate the effectiveness of the main results.In this paper, the synchronization problem of master-slave chaotic neural networks with remote sensors, quantization process, and communication time delays is investigated. The information communication channel between the master chaotic neural network and slave chaotic neural network consists of several remote sensors, with each sensor able to access only partial knowledge of output information of the master neural network. At each sampling instants, each sensor updates its own measurement and only one sensor is scheduled to transmit its latest information to the controller's side in order to update the control inputs for the slave neural network. Thus, such communication process and control strategy are much more energy-saving comparing with the traditional point-to-point scheme. Sufficient conditions for output feedback control

  11. PreImplantation factor (PIF*) promotes embryotrophic and neuroprotective decidual genes: effect negated by epidermal growth factor.

    PubMed

    Duzyj, Christina M; Paidas, Michael J; Jebailey, Lellean; Huang, Jing Shun; Barnea, Eytan R

    2014-01-01

    Intimate embryo-maternal interaction is paramount for pregnancy success post-implantation. The embryo follows a specific developmental timeline starting with neural system, dependent on endogenous and decidual factors. Beyond altered genetics/epigenetics, post-natal diseases may initiate at prenatal/neonatal, post-natal period, or through a continuum. Preimplantation factor (PIF) secreted by viable embryos promotes implantation and trophoblast invasion. Synthetic PIF reverses neuroinflammation in non-pregnant models. PIF targets embryo proteins that protect against oxidative stress and protein misfolding. We report of PIF's embryotrophic role and potential to prevent developmental disorders by regulating uterine milieu at implantation and first trimester. PIF's effect on human implantation (human endometrial stromal cells (HESC)) and first-trimester decidua cultures (FTDC) was examined, by global gene expression (Affymetrix), disease-biomarkers ranking (GeneGo), neuro-specific genes (Ingenuity) and proteins (mass-spectrometry). PIF co-cultured epidermal growth factor (EGF) in both HESC and FTDC (Affymetrix) was evaluated. In HESC, PIF promotes neural differentiation and transmission genes (TLX2, EPHA10) while inhibiting retinoic acid receptor gene, which arrests growth. PIF promotes axon guidance and downregulates EGF-dependent neuroregulin signaling. In FTDC, PIF promotes bone morphogenetic protein pathway (SMAD1, 53-fold) and axonal guidance genes (EPH5) while inhibiting PPP2R2C, negative cell-growth regulator, involved in Alzheimer's and amyotrophic lateral sclerosis. In HESC, PIF affects angiotensin via beta-arrestin, transforming growth factor-beta (TGF-β), notch, BMP, and wingless-int (WNT) signaling pathways that promote neurogenesis involved in childhood neurodevelopmental diseases-autism and also affected epithelial-mesenchymal transition involved in neuromuscular disorders. In FTDC, PIF upregulates neural development and hormone signaling, while

  12. PreImplantation factor (PIF*) promotes embryotrophic and neuroprotective decidual genes: effect negated by epidermal growth factor

    PubMed Central

    2014-01-01

    Background Intimate embryo-maternal interaction is paramount for pregnancy success post-implantation. The embryo follows a specific developmental timeline starting with neural system, dependent on endogenous and decidual factors. Beyond altered genetics/epigenetics, post-natal diseases may initiate at prenatal/neonatal, post-natal period, or through a continuum. Preimplantation factor (PIF) secreted by viable embryos promotes implantation and trophoblast invasion. Synthetic PIF reverses neuroinflammation in non-pregnant models. PIF targets embryo proteins that protect against oxidative stress and protein misfolding. We report of PIF’s embryotrophic role and potential to prevent developmental disorders by regulating uterine milieu at implantation and first trimester. Methods PIF’s effect on human implantation (human endometrial stromal cells (HESC)) and first-trimester decidua cultures (FTDC) was examined, by global gene expression (Affymetrix), disease-biomarkers ranking (GeneGo), neuro-specific genes (Ingenuity) and proteins (mass-spectrometry). PIF co-cultured epidermal growth factor (EGF) in both HESC and FTDC (Affymetrix) was evaluated. Results In HESC, PIF promotes neural differentiation and transmission genes (TLX2, EPHA10) while inhibiting retinoic acid receptor gene, which arrests growth. PIF promotes axon guidance and downregulates EGF-dependent neuroregulin signaling. In FTDC, PIF promotes bone morphogenetic protein pathway (SMAD1, 53-fold) and axonal guidance genes (EPH5) while inhibiting PPP2R2C, negative cell-growth regulator, involved in Alzheimer’s and amyotrophic lateral sclerosis. In HESC, PIF affects angiotensin via beta-arrestin, transforming growth factor-beta (TGF-β), notch, BMP, and wingless-int (WNT) signaling pathways that promote neurogenesis involved in childhood neurodevelopmental diseases—autism and also affected epithelial-mesenchymal transition involved in neuromuscular disorders. In FTDC, PIF upregulates neural development

  13. Processing of speech temporal and spectral information by users of auditory brainstem implants and cochlear implants.

    PubMed

    Azadpour, Mahan; McKay, Colette M

    2014-01-01

    Auditory brainstem implants (ABI) use the same processing strategy as was developed for cochlear implants (CI). However, the cochlear nucleus (CN), the stimulation site of ABIs, is anatomically and physiologically more complex than the auditory nerve and consists of neurons with differing roles in auditory processing. The aim of this study was to evaluate the hypotheses that ABI users are less able than CI users to access speech spectro-temporal information delivered by the existing strategies and that the sites stimulated by different locations of CI and ABI electrode arrays differ in encoding of temporal patterns in the stimulation. Six CI users and four ABI users of Nucleus implants with ACE processing strategy participated in this study. Closed-set perception of aCa syllables (16 consonants) and bVd words (11 vowels) was evaluated via experimental processing strategies that activated one, two, or four of the electrodes of the array in a CIS manner as well as subjects' clinical strategies. Three single-channel strategies presented the overall temporal envelope variations of the signal on a single-implant electrode located at the high-, medium-, and low-frequency regions of the array. Implantees' ability to discriminate within electrode temporal patterns of stimulation for phoneme perception and their ability to make use of spectral information presented by increased number of active electrodes were assessed in the single- and multiple-channel strategies, respectively. Overall percentages and information transmission of phonetic features were obtained for each experimental program. Phoneme perception performance of three ABI users was within the range of CI users in most of the experimental strategies and improved as the number of active electrodes increased. One ABI user performed close to chance with all the single and multiple electrode strategies. There was no significant difference between apical, basal, and middle CI electrodes in transmitting speech

  14. High-Density Stretchable Electrode Grids for Chronic Neural Recording

    PubMed Central

    Tybrandt, Klas; Khodagholy, Dion; Dielacher, Bernd; Stauffer, Flurin; Renz, Aline F.; Buzsáki, György; Vörös, János

    2018-01-01

    Electrical interfacing with neural tissue is key to advancing diagnosis and therapies for neurological disorders, as well as providing detailed information about neural signals. A challenge for creating long-term stable interfaces between electronics and neural tissue is the huge mechanical mismatch between the systems. So far, materials and fabrication processes have restricted the development of soft electrode grids able to combine high performance, long-term stability, and high electrode density, aspects all essential for neural interfacing. Here, this challenge is addressed by developing a soft, high-density, stretchable electrode grid based on an inert, high-performance composite material comprising gold-coated titanium dioxide nanowires embedded in a silicone matrix. The developed grid can resolve high spatiotemporal neural signals from the surface of the cortex in freely moving rats with stable neural recording quality and preserved electrode signal coherence during 3 months of implantation. Due to its flexible and stretchable nature, it is possible to minimize the size of the craniotomy required for placement, further reducing the level of invasiveness. The material and device technology presented herein have potential for a wide range of emerging biomedical applications. PMID:29488263

  15. Amorphous surface layers in Ti-implanted Fe

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Knapp, J.A.; Follstaedt, D.M.; Picraux, S.T.

    1979-01-01

    Implanting Ti into high-purity Fe results in an amorphous surface layer which is composed of not only Fe and Ti, but also C. Implantations were carried out at room temperature over the energy range 90 to 190 keV and fluence range 1 to 2 x 10/sup 16/ at/cm/sup 2/. The Ti-implanted Fe system has been characterized using transmission electron microscopy (TEM), ion backscattering and channeling analysis, and (d,p) nuclear reaction analysis. The amorphous layer was observed to form at the surface and grow inward with increasing Ti fluence. For an implant of 1 x 10/sup 17/ Ti/cm/sup 2/ at 180more » keV the layer thickness was 150 A, while the measured range of the implanted Ti was approx. 550 A. This difference is due to the incorporation of C into the amorphous alloy by C being deposited on the surface during implantation and subsequently diffusing into the solid. Our results indicate that C is an essential constituent of the amorphous phase for Ti concentrations less than or equal to 10 at. %. For the 1 x 10/sup 17/ Ti/cm/sup 2/ implant, the concentration of C in the amorphous phase was approx. 25 at. %, while that of Ti was only approx. 3 at. %. A higher fluence implant of 2 x 10/sup 17/ Ti/cm/sup 2/ produced an amorphous layer with a lower C concentration of approx. 10 at. % and a Ti concentration of approx. 20 at. %.« less

  16. High Mobility SiGe/Si Transistor Structures on Sapphire Substrates Using Ion Implantation

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Mueller, C. H.; Croke, E. T.

    2003-01-01

    High mobility n-type SiGe/Si transistor structures have been fabricated on sapphire substrates by ion implanting phosphorus ions into strained 100 Angstrom thick silicon channels for the first time. The strained Si channels were sandwiched between Si(sub 0.7)Ge(sub 0.3) layers, which, in turn, were deposited on Si(sub 0.7)Ge(sub 0.3) virtual substrates and graded SiGe buffer layers. After the molecular beam epitaxy (MBE) film growth process was completed, ion thick silicon channels implantation and post-annealing were used to introduce donors. The phosphorous ions were preferentially located in the Si channel at a peak concentration of approximately 1x10(exp 18)/cu cm. Room temperature electron mobilities exceeding 750 sq cm/V-sec at carrier densities of 1x10(exp 12)/sq cm were measured. Electron concentration appears to be the key factor that determines mobility, with the highest mobility observed for electron densities in the 1 - 2x10(exp 12)/sq cm range.

  17. Neuroprotective effect of subretinal implants in the RCS rat.

    PubMed

    Pardue, Machelle T; Phillips, Michael J; Yin, Hang; Sippy, Brian D; Webb-Wood, Sarah; Chow, Alan Y; Ball, Sherry L

    2005-02-01

    Retinal prosthetics have been designed to interface with the neural retina by electrically stimulating the remaining retinal circuits after photoreceptor degeneration. However, the electrical stimulation provided by the subretinal implant may also stimulate neurotrophic factors that provide neuroprotection to the retina. This study was undertaken to determine whether electrical stimulation from a subretinal photodiode-based implant has a neuroprotective effect on photoreceptors in the RCS rat, a model of photoreceptor degeneration. Eyes of RCS rats were implanted with an active or inactive device or underwent sham surgery before photoreceptor degeneration. Outer retinal function was assessed with electroretinogram (ERG) recordings weekly until 8 weeks after surgery, at which time retinal tissue was collected and processed for morphologic assessment, including photoreceptor cell counts and retinal layer thickness. At 4 to 6 weeks after surgery, the ERG responses in the active-implant eyes were 30% to 70% greater in b-wave amplitude than the responses from eyes implanted with inactive devices, those undergoing sham surgery, or the nonsurgical control eyes. At 8 weeks after surgery the ERG responses from active-implant eyes were not significantly different from the control groups. However, the number of photoreceptors in eyes implanted with the active or inactive device was significantly greater in the regions over and around the implant versus sham-surgical and nonsurgical control eyes. These results suggest that subretinal electrical stimulation provides temporary preservation of retinal function in the RCS rat. In addition, implantation of an active or inactive device into the subretinal space causes morphologic preservation of photoreceptors in the RCS rat until 8 weeks after surgery. Further studies are needed to determine whether the correlation of neuropreservation with subretinal implantation is due to electrical stimulation and/or a mechanical presence of the

  18. Perianal implantation of bioengineered human internal anal sphincter constructs intrinsically innervated with human neural progenitor cells.

    PubMed

    Raghavan, Shreya; Miyasaka, Eiichi A; Gilmont, Robert R; Somara, Sita; Teitelbaum, Daniel H; Bitar, Khalil N

    2014-04-01

    The internal anal sphincter (IAS) is a major contributing factor to pressure within the anal canal and is required for maintenance of rectoanal continence. IAS damage or weakening results in fecal incontinence. We have demonstrated that bioengineered, intrinsically innervated, human IAS tissue replacements possess key aspects of IAS physiology, such as the generation of spontaneous basal tone and contraction/relaxation in response to neurotransmitters. The objective of this study is to demonstrate the feasibility of implantation of bioengineered IAS constructs in the perianal region of athymic rats. Human IAS tissue constructs were bioengineered from isolated human IAS circular smooth muscle cells and human enteric neuronal progenitor cells. After maturation of the bioengineered constructs in culture, they were implanted operatively into the perianal region of athymic rats. Platelet-derived growth factor was delivered to the implanted constructs through a microosmotic pump. Implanted constructs were retrieved from the animals 4 weeks postimplantation. Animals tolerated the implantation well, and there were no early postoperative complications. Normal stooling was observed during the implantation period. At harvest, implanted constructs were adherent to the perirectal rat tissue and appeared healthy and pink. Immunohistochemical analysis revealed neovascularization. Implanted smooth muscle cells maintained contractile phenotype. Bioengineered constructs responded in vitro in a tissue chamber to neuronally evoked relaxation in response to electrical field stimulation and vasoactive intestinal peptide, indicating the preservation of neuronal networks. Our results indicate that bioengineered innervated IAS constructs can be used to augment IAS function in an animal model. This is a regenerative medicine based therapy for fecal incontinence that would directly address the dysfunction of the IAS muscle. Copyright © 2014 Mosby, Inc. All rights reserved.

  19. A nationwide evaluative study on implant-retained overdentures.

    PubMed

    Cune, M S; de Putter, C; Hoogstraten, J

    1997-01-01

    In the Netherlands, dental implants have been included in the National Dental Insurance Scheme (NDIS) since 1989. Nowadays, out-of-pocket expenditure is low, making implant treatment financially feasible for a large group of edentulous, potential implant candidates. Treatment can be performed by both oral surgeons and general dentists. Results of implant treatment in the literature are usually obtained in academic and specialized centers. In contrast to this, the present study evaluates the quantitative and qualitative aspects of rehabilitation with oral implants in combination with an overdenture when applied on a nationwide scale. For this purpose all patients (n = 5410) treated between January 1989 and July 1992 were extensively documented pre-operatively, implant patients (n = 429) were clinically investigated by two independent observers and the effect of treatment on denture complaints was assessed by means of a questionnaire (n = 460). Only a small proportion of the potential pool of implant candidates is actually being treated, to a constant number of approximately 2000 patients a year. The selected patients have major denture problems and have received relatively high levels of prosthetic care during the last decade. Clinical results are comparable to those reported in the literature, implant survival after 3 years for the lower jaw being 96.3% and for the upper jaw 70.4%. Oral hygiene was frequently considered suboptimal and seen in conjunction with marginal inflammation of the peri-implant mucosa. Subjective results were excellent, patients were quite satisfied with the improvements in the comfort and esthetics of their lower denture. Implant-overdenture treatment, within the guidelines and regulations set by the Dutch NDIS, is a safe and effective treatment alternative, in particular for the rehabilitation of the lower jaw.

  20. An implantable integrated low-power amplifier-microelectrode array for Brain-Machine Interfaces.

    PubMed

    Patrick, Erin; Sankar, Viswanath; Rowe, William; Sanchez, Justin C; Nishida, Toshikazu

    2010-01-01

    One of the important challenges in designing Brain-Machine Interfaces (BMI) is to build implantable systems that have the ability to reliably process the activity of large ensembles of cortical neurons. In this paper, we report the design, fabrication, and testing of a polyimide-based microelectrode array integrated with a low-power amplifier as part of the Florida Wireless Integrated Recording Electrode (FWIRE) project at the University of Florida developing a fully implantable neural recording system for BMI applications. The electrode array was fabricated using planar micromachining MEMS processes and hybrid packaged with the amplifier die using a flip-chip bonding technique. The system was tested both on bench and in-vivo. Acute and chronic neural recordings were obtained from a rodent for a period of 42 days. The electrode-amplifier performance was analyzed over the chronic recording period with the observation of a noise floor of 4.5 microVrms, and an average signal-to-noise ratio of 3.8.

  1. Neural Energy Supply-Consumption Properties Based on Hodgkin-Huxley Model

    PubMed Central

    2017-01-01

    Electrical activity is the foundation of the neural system. Coding theories that describe neural electrical activity by the roles of action potential timing or frequency have been thoroughly studied. However, an alternative method to study coding questions is the energy method, which is more global and economical. In this study, we clearly defined and calculated neural energy supply and consumption based on the Hodgkin-Huxley model, during firing action potentials and subthreshold activities using ion-counting and power-integral model. Furthermore, we analyzed energy properties of each ion channel and found that, under the two circumstances, power synchronization of ion channels and energy utilization ratio have significant differences. This is particularly true of the energy utilization ratio, which can rise to above 100% during subthreshold activity, revealing an overdraft property of energy use. These findings demonstrate the distinct status of the energy properties during neuronal firings and subthreshold activities. Meanwhile, after introducing a synapse energy model, this research can be generalized to energy calculation of a neural network. This is potentially important for understanding the relationship between dynamical network activities and cognitive behaviors. PMID:28316842

  2. A three channel telemetry system

    NASA Technical Reports Server (NTRS)

    Lesho, Jeffery C.; Eaton, Harry A. C.

    1993-01-01

    A three channel telemetry system intended for biomedical applications is described. The transmitter is implemented in a single chip using a 2 micron BiCMOS processes. The operation of the system and the test results from the latest chip are discussed. One channel is always dedicated to temperature measurement while the other two channels are generic. The generic channels carry information from transducers that are interfaced to the system through on-chip general purpose operational amplifiers. The generic channels have different bandwidths: one from dc to 250 Hz and the other from dc to 1300 Hz. Each generic channel modulates a current controlled oscillator to produce a frequency modulated signal. The two frequency modulated signals are summed and used to amplitude modulate the temperature signal which acts as a carrier. A near-field inductive link telemeters the combined signals over a short distance. The chip operates on a supply voltage anywhere from 2.5 to 3.6 Volts and draws less than 1 mA when transmitting a signal. The chip can be incorporated into ingestible, implantable and other configurations. The device can free the patient from tethered data collection systems and reduces the possibility of infection from subcutaneous leads. Data telemetry can increase patient comfort leading to a greater acceptance of monitoring.

  3. Electrical resistivity measurements in the mammalian cochlea after neural degeneration.

    PubMed

    Micco, Alan G; Richter, Claus-Peter

    2006-08-01

    In the present series of experiments, the effect of neural degeneration on the cochlear structure electrical resistivities was evaluated to test if it alters the current flow in the cochlea and if increased current levels are needed to stimulate the impaired cochlea. In cochlear implants, frequency information is encoded in part by stimulating discrete populations of spiral ganglion cells along the cochlea. However, electrical properties of the cochlear structures result in shunting of the current away from the auditory neurons. This consumes energy, makes cochlear implants less efficient, and drastically reduces battery life. Models of the electrically stimulated cochlea serve to make predictions on current paths using modified and improved cochlear implant electrodes. However, one of the model's shortcomings is that most of the values for tissue impedances are not direct measurements. They are derived from bulk impedance measurements, which are fitted to lumped-element models. The four-electrode reflection-coefficient technique was used to measure resistivities in the gerbil cochlea. In vivo and in vitro (the hemicochlea) models were used. Measurements were made in normal and in deafened animals. Cochlear damage was induced by neomycin injection into the animals' middle ears. Neural degeneration was allowed to occur over 2 months before performing the measurements in the deafened animals. The resistivity values in deafened animals were smaller than in the normal-hearing animals, thus altering the current flow within the cochlea. Resistivity changes and subsequent changes in current path should be considered in future designs of cochlear implants.

  4. Simultaneous sinus lift and implant installation: prospective study of consecutive two hundred seventeen sinus lift and four hundred sixty-two implants.

    PubMed

    Cha, Hyun-Suk; Kim, Andrew; Nowzari, Hessam; Chang, Hoo-Sun; Ahn, Kang-Min

    2014-06-01

    If less than 4 mm of residual bone is remained in posterior maxilla, two-stage operation is recommended for implant installation. However, if primary stability could be obtained using tapered designed implants, one-stage surgery could be performed with reliable success rate in severely resorbed maxilla. The purpose of this prospective study was to evaluate survival and success rates of the implants simultaneously placed into grafted sinus using rough-surfaced implant. A total of two hundred seventeen consecutive sinus lifting through lateral approach and four hundred sixty-two simultaneous implants were installed from November 2003 for 5.5 years. Xenogenic bone was used solely for bone graft materials. Second surgery was performed around 6 months after operation and porcelain fused metal or gold crown was used for definitive restorations. Cumulative survival and success rates were evaluated according to residual alveolar bone height (RABH), smoking status, and Schneiderian membrane perforation. The mean follow-up was 57.1 ± 15.6 (36-98) months. Of the four hundred sixty-two implants, two hundred sixty-two implants (56.7%: group 1) were installed in posterior maxilla less than 4-mm RABH and two hundred implants (43.3%: group 2) were placed in over 5-mm RABH. The cumulative survival and success rates were 98.91% and 96.54%. There was no statistically significant difference in success rate between group 1 and group 2 (p = .3135). Perforation of the membrane was not related to success (p = .7162), but smoking status is significantly related with implant failure (p = .0003). Sinus lifting with simultaneous implant placement could be used to treat atrophic maxilla in patients with minimal RABH when initial stability could be obtained by using taper designed implants with surgical techniques. Smoking is a possible factor for implant failure. Membrane perforation did not have an adverse effect on implant success if the membrane was repaired with absorbable membrane and

  5. Molecular Basis of Paraltyic Neurotoxin Action on Voltage-Sensitive Sodium Channels

    DTIC Science & Technology

    1985-10-14

    of 9,700 daltons isolated from the coral Goni2oora gy. (1). The toxin enhances neurally mediated contraction of blood vessels and taenia coli of the...sites on the solium channel and to identify the site of GPT action within the structure of the sodium channel protein. 2. Site of Action of Brvyetoxin

  6. Voltage-gated K+ channel modulators as neuroprotective agents.

    PubMed

    Leung, Yuk-Man

    2010-05-22

    A manifestation in neurodegeneration is apoptosis of neurons. Neurons undergoing apoptosis may lose a substantial amount of cytosolic K+ through a number of pathways including K+ efflux via voltage-gated K+ (Kv) channels. The consequent drop in cytosolic [K+] relieves inhibition of an array of pro-apoptotic enzymes such as caspases and nucleases. Blocking Kv channels has been known to prevent neuronal apoptosis by preventing K+ efflux. Some neural diseases such as epilepsy are caused by neuronal hyperexcitability, which eventually may lead to neuronal apoptosis. Reduction in activities of A-type Kv channels and Kv7 subfamily members is amongst the etiological causes of neuronal hyperexcitation; enhancing the opening of these channels may offer opportunities of remedy. This review discusses the potential uses of Kv channel modulators as neuroprotective drugs.

  7. When Hearing Is Tricky: Speech Processing Strategies in Prelingually Deafened Children and Adolescents with Cochlear Implants Having Good and Poor Speech Performance

    PubMed Central

    Ortmann, Magdalene; Zwitserlood, Pienie; Knief, Arne; Baare, Johanna; Brinkheetker, Stephanie; am Zehnhoff-Dinnesen, Antoinette; Dobel, Christian

    2017-01-01

    Cochlear implants provide individuals who are deaf with access to speech. Although substantial advancements have been made by novel technologies, there still is high variability in language development during childhood, depending on adaptation and neural plasticity. These factors have often been investigated in the auditory domain, with the mismatch negativity as an index for sensory and phonological processing. Several studies have demonstrated that the MMN is an electrophysiological correlate for hearing improvement with cochlear implants. In this study, two groups of cochlear implant users, both with very good basic hearing abilities but with non-overlapping speech performance (very good or very poor speech performance), were matched according to device experience and age at implantation. We tested the perception of phonemes in the context of specific other phonemes from which they were very hard to discriminate (e.g., the vowels in /bu/ vs. /bo/). The most difficult pair was individually determined for each participant. Using behavioral measures, both cochlear implants groups performed worse than matched controls, and the good performers performed better than the poor performers. Cochlear implant groups and controls did not differ during time intervals typically used for the mismatch negativity, but earlier: source analyses revealed increased activity in the region of the right supramarginal gyrus (220–260 ms) in good performers. Poor performers showed increased activity in the left occipital cortex (220–290 ms), which may be an index for cross-modal perception. The time course and the neural generators differ from data from our earlier studies, in which the same phonemes were assessed in an easy-to-discriminate context. The results demonstrate that the groups used different language processing strategies, depending on the success of language development and the particular language context. Overall, our data emphasize the role of neural plasticity and use

  8. Long-term follow-up of patients with retinitis pigmentosa (RP) receiving intraocular ciliary neurotrophic factor implants

    PubMed Central

    Birch, David G.; Bennett, Lea D.; Duncan, Jacque L.; Weleber, Richard G.; Pennesi, Mark E.

    2016-01-01

    Purpose To evaluate the long-term efficacy of ciliary neurotrophic factor delivered via an intraocular encapsulated cell implant for the treatment of retinitis pigmentosa (RP). Design Long-term follow up of a multicenter, sham-controlled study. Methods Thirty-six patients at three CNTF4 sites were randomly assigned to receive a high- or low- dose implant in one eye and sham surgery in the fellow eye. The primary endpoint (change in visual field sensitivity at 12 months) has been reported previously.1 Here we report long-term visual acuity, visual field and optical coherence tomography (OCT) outcomes in 24 patients either retaining or explanting the device at 24 months relative to sham-treated eyes. Results Eyes retaining the implant showed significantly greater visual field loss from baseline than either explanted eyes or sham eyes through 42 months. By 60 months and continuing through 96 months, visual field loss was comparable among sham-treated eyes, eyes retaining the implant and explanted eyes, as was visual acuity and OCT macular volume. Conclusions Over the short term, ciliary neurotrophic factor released continuously from an intra-vitreal implant lead to loss of total visual field sensitivity that was greater than the natural progression in the sham-treated eye. This additional loss of sensitivity related to the active implant was reversible when the implant was removed. Over the long term (60 – 96 months), there was no evidence of efficacy for visual acuity, visual field sensitivity or OCT measures of retinal structure. PMID:27457255

  9. Implantable electrode for recording nerve signals in awake animals

    NASA Technical Reports Server (NTRS)

    Ninomiya, I.; Yonezawa, Y.; Wilson, M. F.

    1976-01-01

    An implantable electrode assembly consisting of collagen and metallic electrodes was constructed to measure simultaneously neural signals from the intact nerve and bioelectrical noises in awake animals. Mechanical artifacts, due to bodily movement, were negligibly small. The impedance of the collagen electrodes, measured in awake cats 6-7 days after implantation surgery, ranged from 39.8-11.5 k ohms at a frequency range of 20-5 kHz. Aortic nerve activity and renal nerve activity, measured in awake conditions using the collagen electrode, showed grouped activity synchronous with the cardiac cycle. Results indicate that most of the renal nerve activity was from postganglionic sympathetic fibers and was inhibited by the baroceptor reflex in the same cardiac cycle.

  10. Design of a Closed-Loop, Bidirectional Brain Machine Interface System With Energy Efficient Neural Feature Extraction and PID Control.

    PubMed

    Liu, Xilin; Zhang, Milin; Richardson, Andrew G; Lucas, Timothy H; Van der Spiegel, Jan

    2017-08-01

    This paper presents a bidirectional brain machine interface (BMI) microsystem designed for closed-loop neuroscience research, especially experiments in freely behaving animals. The system-on-chip (SoC) consists of 16-channel neural recording front-ends, neural feature extraction units, 16-channel programmable neural stimulator back-ends, in-channel programmable closed-loop controllers, global analog-digital converters (ADC), and peripheral circuits. The proposed neural feature extraction units includes 1) an ultra low-power neural energy extraction unit enabling a 64-step natural logarithmic domain frequency tuning, and 2) a current-mode action potential (AP) detection unit with time-amplitude window discriminator. A programmable proportional-integral-derivative (PID) controller has been integrated in each channel enabling a various of closed-loop operations. The implemented ADCs include a 10-bit voltage-mode successive approximation register (SAR) ADC for the digitization of the neural feature outputs and/or local field potential (LFP) outputs, and an 8-bit current-mode SAR ADC for the digitization of the action potential outputs. The multi-mode stimulator can be programmed to perform monopolar or bipolar, symmetrical or asymmetrical charge balanced stimulation with a maximum current of 4 mA in an arbitrary channel configuration. The chip has been fabricated in 0.18 μ m CMOS technology, occupying a silicon area of 3.7 mm 2 . The chip dissipates 56 μW/ch on average. General purpose low-power microcontroller with Bluetooth module are integrated in the system to provide wireless link and SoC configuration. Methods, circuit techniques and system topology proposed in this work can be used in a wide range of relevant neurophysiology research, especially closed-loop BMI experiments.

  11. Food Impaction and Periodontal/Peri-Implant Tissue Conditions in Relation to the Embrasure Dimensions Between Implant-Supported Fixed Dental Prostheses and Adjacent Teeth: A Cross-Sectional Study.

    PubMed

    Jeong, Jin-Seok; Chang, Moontaek

    2015-12-01

    Food impaction and periodontal/peri-implant tissue conditions were evaluated in relation to the embrasure dimensions between implant-supported fixed dental prostheses (FDPs) and adjacent teeth. A total of 215 embrasures of 150 FDPs in 100 patients (55 males and 45 females, aged 27 to 83 years; mean age: 56 years) were included in the study. Clinical assessments of the periodontal/peri-implant mucosal conditions, radiographic assessments of embrasure dimensions, and overall patient satisfaction were used as explanatory variables for the food impaction and periodontal/peri-implant tissue conditions adjacent to implant-supported FDPs in the generalized estimating equation (GEE) analysis. Food impaction was reported in 96 (44.7%) of 215 embrasures between implant-supported FDPs and adjacent teeth. Food impaction was reported more frequently in the embrasures with proximal contact loss than in those with tight contact (P = 0.009). Overall patient satisfaction was influenced negatively by food impaction in the proximal embrasures (P = 0.01). Among embrasure dimensions, only the embrasure surface area (ESA) significantly influenced food impaction (P = 0.03). Significant influences of various embrasure dimensions on the periodontal/peri-implant mucosal conditions and bone level at the implant were found in the univariate and multivariate GEE analyses. Food impaction between implant-supported FDPs and adjacent teeth occurred more frequently when proximal contact was lost and ESA increased. Food impaction negatively affected overall patient satisfaction. Embrasure dimensions influenced the periodontal/peri-implant mucosal conditions and bone level at the implant.

  12. Perception of speech in reverberant conditions using AM-FM cochlear implant simulation.

    PubMed

    Drgas, Szymon; Blaszak, Magdalena A

    2010-10-01

    This study assessed the effects of speech misidentification and cognitive processing errors in normal-hearing adults listening to degraded auditory input signals simulating cochlear implants in reverberation conditions. Three variables were controlled: number of vocoder channels (six and twelve), instantaneous frequency change rate (none, 50, 400 Hz), and enclosures (different reverberation conditions). The analyses were made on the basis of: (a) nonsense word recognition scores for eight young normal-hearing listeners, (b) 'ease of listening' based on the time of response, and (c) the subjective measure of difficulty. The maximum score of speech intelligibility in cochlear implant simulation was 70% for non-reverberant conditions with a 12-channel vocoder and changes of instantaneous frequency limited to 400 Hz. In the presence of reflections, word misidentification was about 10-20 percentage points higher. There was little difference between the 50 and 400 Hz frequency modulation cut-off for the 12-channel vocoder; however, in the case of six channels this difference was more significant. The results of the experiment suggest that the information other than F0, that is carried by FM, can be sufficient to improve speech intelligibility in the real-world conditions.

  13. Displacement damage dose and implantation temperature effects on the trapping and release of deuterium implanted into SiC

    NASA Astrophysics Data System (ADS)

    Muñoz, P.; García-Cortés, I.; Sánchez, F. J.; Moroño, A.; Malo, M.; Hodgson, E. R.

    2017-09-01

    Radiation damage to flow channel insert (FCI) materials is an important issue for the concept of dual-coolant blanket development in future fusion devices. Silicon Carbide (SiC) is one of the most suitable materials for FCI. Because of the severe radiation environment and exposure to tritium during operation it is of fundamental importance to study hydrogen isotope trapping and release in these materials. Here the trapping, detrapping, and diffusion of deuterium implanted into SiC is studied in correlation with pre- and post-damage induced under different conditions. For this, SiC samples are pre-damaged with 50 keV Ne+ ions at different temperatures (20, 200, 450, 700 °C) to different damage doses (1, 3.6, 7 dpa). Next, deuterium is introduced into the samples at 450 °C by ion implantation at 7 keV. The implanted deuterium retained in the sample is analysed using secondary ion mass spectrometry (SIMS) and thermo-stimulated desorption (TSD) measurements. The results indicate that with increasing neon damage dose, the maximum deuterium desorption occurs at higher temperatures. In contrast, when increasing neon implantation temperature for a fixed dose, the maximum deuterium desorption release temperature decreases. It is interpreted that the neon bombardment produces thermally stable traps for hydrogen isotopes and the stability of this damage increases with neon pre-implantation dose. A decrease of the trapping of implanted deuterium is also observed to occur due to damage recovery by thermal annealing during pre-implantation at the higher temperatures. Finally, direct particle bombardment induced deuterium release is also observed.

  14. Canadian breast implant cohort: extended follow-up of cancer incidence.

    PubMed

    Pan, Sai Yi; Lavigne, Eric; Holowaty, Eric J; Villeneuve, Paul J; Xie, Lin; Morrison, Howard; Brisson, Jacques

    2012-10-01

    Cosmetic breast implants are not associated with increased breast cancer incidence, but variations of risk according to implant characteristics are still poorly understood. As well, the assessment of cancer risk for sites other than breast needs to be clarified. The purpose of this study was to fill these research gaps. This study presents an extended analysis of 10 more years of follow-up of a large Canadian cohort of women who received either cosmetic breast implants (n = 24,558) or other cosmetic surgery (15,893). Over 70% of the implant cohort was followed for over 20 years. Cancer incidence among implant women was compared to those of controls using multivariate Poisson models and the general female population using the standardized incidence ratios (SIRs). Women with breast implants had reduced rates of breast and endometrial cancers compared to other surgery women. Subglandular implants were associated to a reduced rate of breast cancer compared to submuscular implants [incidence rate ratio (IRR) = 0.78, 95% confidence interval (CI) = 0.63-0.96] and this reduction persisted over time. We observed a sevenfold increased rate (IRR = 7.36, 95% CI = 1.86-29.12) of breast cancer in the first 5 years after the date of surgery for polyurethane-coated subglandular implant women but this IRR decreased progressively over time (p value for trend = 0.02). We also observed no increased risk of rarer forms of cancer among augmented women. A reduction in breast cancer incidence was observed for women with subglandular implants relative to women with submuscular implants. Possible increase of breast cancer incidence shortly after breast augmentation with polyurethane implants needs to be verified. Copyright © 2012 UICC.

  15. Use pattern for contraceptive implants in Norway.

    PubMed

    Øvre-Eide, Vigdis; Skjeldestad, Finn Egil

    2016-11-01

    Knowledge about global use patterns of contraceptive implants is limited. This study aims to describe implant use patterns from a user and a prescriber perspective. In a cross-sectional design, we estimated the annual number of users by calculating doses sold per 1000 women-years in the Norwegian Prescription Database for 2006-2012. For each contraceptive method, we calculated on an annual basis a proportion of defined daily doses of all hormonal contraceptives in five-year age groups. Data were analyzed in SPSS version 22, using chi-square test, t-test, and survival analysis. Sales from pharmacies for contraceptive implants more than doubled over the study years and were consistently higher in the younger age groups. The collection rate was 9.3 per 1000 women in 2012, when implant sales amounted to 2.4% of all daily doses of hormonal contraceptives sold. General practitioners and doctors with no specialty were the major prescribers to those starting to use contraceptive implants (starters), whereas gynecologists prescribed nearly 12% of the volume, with a higher proportion to women >35 years of age than younger women. The cumulative proportions of continued users at 6, 12, 24, and 36 months were 96.1, 78.6, 51.9, and 34.9%, respectively, significantly lower for users who had prescribing doctors with no specialty. At end of the first expiration period, 21% of starters continued using implants. Implants play a minor role in the overall use of hormonal contraception in Norway. One in five starters continue as long-term users. © 2016 Nordic Federation of Societies of Obstetrics and Gynecology.

  16. Evaluation of single-tooth implants in the second molar region: a 5-year life-table analysis of a retrospective study.

    PubMed

    Koo, Ki-Tae; Wikesjö, Ulf M E; Park, Jang-Yeol; Kim, Tae-Il; Seol, Yang-Jo; Ku, Young; Rhyu, In-Chul; Chung, Chong-Pyoung; Lee, Yong-Moo

    2010-09-01

    To our knowledge, no study has evaluated the success or survival rate of single-tooth implants that replaced missing maxillary and mandibular second molars. The purpose of the present study was to evaluate the 1- to 5-year cumulative survival rate (CSR) for single-tooth implants placed in the second molar region and the effects of associated factors. Four hundred eighty-nine patients (298 males and 191 females; age range: 23 to 91 years; mean age: 47 years) who were admitted to the Seoul National University Dental Hospital between March 2003 and July 2008 and treated with single-tooth implants in the second molar region (227 maxillary implants and 294 mandibular implants; total: 521 implants) were included in the study. Thirty-two subjects received two implants each. A 1- to 5-year CSR was calculated using a life-table analysis. A comparison of CSRs between maxillary versus mandibular implants, one-stage versus two-stage implants, short (10 mm) implants, and standard-diameter (or=5.0 mm) implants was performed using Wilcoxon (Gehan) statistics. P <0.05 was considered significant. Fifteen of the 521 implants were lost between insertion and the follow-up examinations. The 1- to 5-year CSR was 95.1%. There were no statistically significant differences in CSRs between implants placed in maxillas and mandibles (96.3% versus 94.9%, respectively; P = 0.084), one- and two-stage implants (95.6% versus 94.7%, respectively; P = 0.267), short and long implants (100% versus 95.1%, respectively; P = 0.582), and standard- and wide-diameter implants (93.8% versus 96.8%, respectively; P = 0.065). Within the limitations of the study, the placement of single-tooth implants in the second molar region was an effective and reliable treatment modality. Also, associated factors such as implant diameter, length, and location (the maxilla versus the mandible) may not have an impact on the long-term success of implants.

  17. The Influence of Personality on Neural Mechanisms of Observational Fear and Reward Learning

    ERIC Educational Resources Information Center

    Hooker, Christine I.; Verosky, Sara C.; Miyakawa, Asako; Knight, Robert T.; D'Esposito, Mark

    2008-01-01

    Fear and reward learning can occur through direct experience or observation. Both channels can enhance survival or create maladaptive behavior. We used fMRI to isolate neural mechanisms of observational fear and reward learning and investigate whether neural response varied according to individual differences in neuroticism and extraversion.…

  18. Glucose-6-phosphate isomerase is necessary for embryo implantation in the domestic ferret

    PubMed Central

    Schulz, Laura Clamon; Bahr, Janice M.

    2003-01-01

    The mechanism of implantation in carnivores is poorly understood. However, a previously unidentified 60-kDa protein has been shown to be necessary for embryo implantation in ferrets. Here we identify this protein as glucose-6-phosphate isomerase (GPI). GPI is expressed by the corpus luteum on days 6–9 of pregnancy, the time at which implantation-promoting activity has been found in corpora lutea. Passive immunization against GPI reduced the number of implantation sites in pregnant ferrets in a dose-dependent manner. GPI is a multifunctional protein. Although first identified for its role in glycolysis, GPI has since been implicated in neural growth, lymphocyte maturation, and metastasis. This study demonstrates a previously uncharacterized function of this protein that may represent the natural motility-stimulating activity that has been co-opted by tumor cells. PMID:12826606

  19. Requirement for Foxd3 in the maintenance of neural crest progenitors.

    PubMed

    Teng, Lu; Mundell, Nathan A; Frist, Audrey Y; Wang, Qiaohong; Labosky, Patricia A

    2008-05-01

    Understanding the molecular mechanisms of stem cell maintenance is crucial for the ultimate goal of manipulating stem cells for the treatment of disease. Foxd3 is required early in mouse embryogenesis; Foxd3(-/-) embryos fail around the time of implantation, cells of the inner cell mass cannot be maintained in vitro, and blastocyst-derived stem cell lines cannot be established. Here, we report that Foxd3 is required for maintenance of the multipotent mammalian neural crest. Using tissue-specific deletion of Foxd3 in the neural crest, we show that Foxd3(flox/-); Wnt1-Cre mice die perinatally with a catastrophic loss of neural crest-derived structures. Cranial neural crest tissues are either missing or severely reduced in size, the peripheral nervous system consists of reduced dorsal root ganglia and cranial nerves, and the entire gastrointestinal tract is devoid of neural crest derivatives. These results demonstrate a global role for this transcriptional repressor in all aspects of neural crest maintenance along the anterior-posterior axis, and establish an unprecedented molecular link between multiple divergent progenitor lineages of the mammalian embryo.

  20. Multicentre investigation on electrically evoked compound action potential and stapedius reflex: how do these objective measures relate to implant programming parameters?

    PubMed

    Van Den Abbeele, Thierry; Noël-Petroff, Nathalie; Akin, Istemihan; Caner, Gül; Olgun, Levent; Guiraud, Jeanne; Truy, Eric; Attias, Josef; Raveh, Eyal; Belgin, Erol; Sennaroglu, Gonca; Basta, Dietmar; Ernst, Arneborg; Martini, Alessandro; Rosignoli, Monica; Levi, Haya; Elidan, Joseph; Benghalem, Abdelhamid; Amstutz-Montadert, Isabelle; Lerosey, Yannick; De Vel, Eddy; Dhooge, Ingeborg; Hildesheimer, Minka; Kronenberg, Jona; Arnold, Laure

    2012-02-01

    The aims of this study were to collect data on electrically evoked compound action potential (eCAP) and electrically evoked stapedius reflex thresholds (eSRT) in HiResolution(TM) cochlear implant (CI) users, and to explore the relationships between these objective measures and behavioural measures of comfort levels (M-levels). A prospective study on newly implanted subjects was designed. The eCAP was measured intra-operatively and at first fitting through neural response imaging (NRI), using the SoundWave(TM) fitting software. The eSRT was measured intra-operatively by visual monitoring of the stapes, using both single-electrode stimulation and speech bursts (four electrodes stimulated at the same time). Measures of M-levels were performed according to standard clinical practice and collected at first fitting, 3 and 6 months of CI use. One hundred seventeen subjects from 14 centres, all implanted unilaterally with a HiResolution CII Bionic Ear(®) or HiRes 90K(®), were included in the study. Speech burst stimulation elicited a significantly higher eSRT success rate than single-electrode stimulation, 84 vs. 64% respectively. The NRI success rate was 81% intra-operatively, significantly increasing to 96% after 6 months. Fitting guidelines were defined on the basis of a single NRI measurement. Correlations, analysis of variance, and multiple regression analysis were applied to generate a predictive model for the M-levels. Useful insights were produced into the behaviour of objective measures according to time, electrode location, and fitting parameters. They may usefully assist in programming the CI when no reliable feedback is obtained through standard behavioural procedures.

  1. Modeling and Characterization of Capacitive Elements With Tissue as Dielectric Material for Wireless Powering of Neural Implants.

    PubMed

    Erfani, Reza; Marefat, Fatemeh; Sodagar, Amir M; Mohseni, Pedram

    2018-05-01

    This paper reports on the modeling and characterization of capacitive elements with tissue as the dielectric material, representing the core building block of a capacitive link for wireless power transfer to neural implants. Each capacitive element consists of two parallel plates that are aligned around the tissue layer and incorporate a grounded, guarded, capacitive pad to mitigate the adverse effect of stray capacitances and shield the plates from external interfering electric fields. The plates are also coated with a biocompatible, insulating, coating layer on the inner side of each plate in contact with the tissue. A comprehensive circuit model is presented that accounts for the effect of the coating layers and is validated by measurements of the equivalent capacitance as well as impedance magnitude/phase of the parallel plates over a wide frequency range of 1 kHz-10 MHz. Using insulating coating layers of Parylene-C at a thickness of and Parylene-N at a thickness of deposited on two sets of parallel plates with different sizes and shapes of the guarded pad, our modeling and characterization results accurately capture the effect of the thickness and electrical properties of the coating layers on the behavior of the capacitive elements over frequency and with different tissues.

  2. Feed-forward neural network model for hunger and satiety related VAS score prediction.

    PubMed

    Krishnan, Shaji; Hendriks, Henk F J; Hartvigsen, Merete L; de Graaf, Albert A

    2016-07-07

    An artificial neural network approach was chosen to model the outcome of the complex signaling pathways in the gastro-intestinal tract and other peripheral organs that eventually produce the satiety feeling in the brain upon feeding. A multilayer feed-forward neural network was trained with sets of experimental data relating concentration-time courses of plasma satiety hormones to Visual Analog Scales (VAS) scores. The network successfully predicted VAS responses from sets of satiety hormone data obtained in experiments using different food compositions. The correlation coefficients for the predicted VAS responses for test sets having i) a full set of three satiety hormones, ii) a set of only two satiety hormones, and iii) a set of only one satiety hormone were 0.96, 0.96, and 0.89, respectively. The predicted VAS responses discriminated the satiety effects of high satiating food types from less satiating food types both in orally fed and ileal infused forms. From this application of artificial neural networks, one may conclude that neural network models are very suitable to describe situations where behavior is complex and incompletely understood. However, training data sets that fit the experimental conditions need to be available.

  3. Factors affecting speech understanding in gated interference: Cochlear implant users and normal-hearing listeners

    NASA Astrophysics Data System (ADS)

    Nelson, Peggy B.; Jin, Su-Hyun

    2004-05-01

    Previous work [Nelson, Jin, Carney, and Nelson (2003), J. Acoust. Soc. Am 113, 961-968] suggested that cochlear implant users do not benefit from masking release when listening in modulated noise. The previous findings indicated that implant users experience little to no release from masking when identifying sentences in speech-shaped noise, regardless of the modulation frequency applied to the noise. The lack of masking release occurred for all implant subjects who were using three different devices and speech processing strategies. In the present study, possible causes of this reduced masking release in implant listeners were investigated. Normal-hearing listeners, implant users, and normal-hearing listeners presented with a four-band simulation of a cochlear implant were tested for their understanding of sentences in gated noise (1-32 Hz gate frequencies) when the duty cycle of the noise was varied from 25% to 75%. No systematic effect of noise duty cycle on implant and simulation listeners' performance was noted, indicating that the masking caused by gated noise is not only energetic masking. Masking release significantly increased when the number of spectral channels was increased from 4 to 12 for simulation listeners, suggesting that spectral resolution is important for masking release. Listeners were also tested for their understanding of gated sentences (sentences in quiet interrupted by periods of silence ranging from 1 to 32 Hz as a measure of auditory fusion, or the ability to integrate speech across temporal gaps. Implant and simulation listeners had significant difficulty understanding gated sentences at every gate frequency. When the number of spectral channels was increased for simulation listeners, their ability to understand gated sentences improved significantly. Findings suggest that implant listeners' difficulty understanding speech in modulated conditions is related to at least two (possibly related) factors: degraded spectral information and

  4. Acid-sensing ion channels: trafficking and synaptic function.

    PubMed

    Zha, Xiang-ming

    2013-01-02

    Extracellular acidification occurs in the brain with elevated neural activity, increased metabolism, and neuronal injury. This reduction in pH can have profound effects on brain function because pH regulates essentially every single biochemical reaction. Therefore, it is not surprising to see that Nature evolves a family of proteins, the acid-sensing ion channels (ASICs), to sense extracellular pH reduction. ASICs are proton-gated cation channels that are mainly expressed in the nervous system. In recent years, a growing body of literature has shown that acidosis, through activating ASICs, contributes to multiple diseases, including ischemia, multiple sclerosis, and seizures. In addition, ASICs play a key role in fear and anxiety related psychiatric disorders. Several recent reviews have summarized the importance and therapeutic potential of ASICs in neurological diseases, as well as the structure-function relationship of ASICs. However, there is little focused coverage on either the basic biology of ASICs or their contribution to neural plasticity. This review will center on these topics, with an emphasis on the synaptic role of ASICs and molecular mechanisms regulating the spatial distribution and function of these ion channels.

  5. Implantable telemetry for small animals

    NASA Astrophysics Data System (ADS)

    1982-03-01

    A series of totally implantable telemetry devices for use in measuring deep body parameters in small animals were developed. Under a collaborative agreement with NASA, several of these systems; the continuous wave Doppler ultrasonic flowmeter, the multichannel telemetry system, and the inductively-powered dual channel cardiac pacer were evaluated in a series of ten mongrel dogs (15 to 20 kg.). These systems were used to measure ascending aortic and coronary blood flow, aortic pressure, and subcutaneous EKG.

  6. Implantable telemetry for small animals

    NASA Technical Reports Server (NTRS)

    1982-01-01

    A series of totally implantable telemetry devices for use in measuring deep body parameters in small animals were developed. Under a collaborative agreement with NASA, several of these systems; the continuous wave Doppler ultrasonic flowmeter, the multichannel telemetry system, and the inductively-powered dual channel cardiac pacer were evaluated in a series of ten mongrel dogs (15 to 20 kg.). These systems were used to measure ascending aortic and coronary blood flow, aortic pressure, and subcutaneous EKG.

  7. Noise from implantable Cooper cable.

    PubMed

    Carrington, V; Zhou, L; Donaldson, N

    2005-09-01

    Cooper cable is made for implanted devices, usually for connection to stimulating electrodes. An experiment has been performed to see whether these cables would be satisfactory for recording electroneurogram (ENG) signals from cuffs. Four cables were subjected to continuous flexion at 2 Hz while submerged in saline. The cables were connected to a low-noise amplifier, and the noise was measured using a spectrum analyser. These cables had not fractured after 184 million flexions, and the noise in the neural band (500-5000 Hz) had not increased owing to age. Noise in the ENG band increased by less than 3 dB owing to the motion. A fifth, worn cable did fail during the experiment, the conductors becoming exposed to the saline, but this was only apparent by extra noise when the cable was in motion. After 184 million flexions, the four cables were given a more severe test: instead of being connected to the amplifier reference node, two of the four cores of each cable were connected to 18V batteries. Two of the cables were then noisier, but only when in motion, presumably because of leakage between cores. Cooper cables are excellent for transmitting neural signals alone; transmission in one cable of neural signals and power supplies should be avoided if possible.

  8. Cochlear implants and spoken language processing abilities: review and assessment of the literature.

    PubMed

    Peterson, Nathaniel R; Pisoni, David B; Miyamoto, Richard T

    2010-01-01

    Cochlear implants (CIs) process sounds electronically and then transmit electric stimulation to the cochlea of individuals with sensorineural deafness, restoring some sensation of auditory perception. Many congenitally deaf CI recipients achieve a high degree of accuracy in speech perception and develop near-normal language skills. Post-lingually deafened implant recipients often regain the ability to understand and use spoken language with or without the aid of visual input (i.e. lip reading). However, there is wide variation in individual outcomes following cochlear implantation, and some CI recipients never develop useable speech and oral language skills. The causes of this enormous variation in outcomes are only partly understood at the present time. The variables most strongly associated with language outcomes are age at implantation and mode of communication in rehabilitation. Thus, some of the more important factors determining success of cochlear implantation are broadly related to neural plasticity that appears to be transiently present in deaf individuals. In this article we review the expected outcomes of cochlear implantation, potential predictors of those outcomes, the basic science regarding critical and sensitive periods, and several new research directions in the field of cochlear implantation.

  9. Disparity channels in early vision

    PubMed Central

    Roe, AW; Parker, AJ; Born, RT; DeAngelis, GC

    2008-01-01

    The last decade has seen a dramatic increase in our knowledge of the neural basis of stereopsis. New cortical areas have been found to represent binocular disparities, new representations of disparity information (e.g., relative disparity signals) have been uncovered, the first topographic maps of disparity have been measured, and the first causal links between neural activity and depth perception have been established. Equally exciting is the finding that training and experience affects how signals are channeled through different brain areas, a flexibility that may be crucial for learning, plasticity, and recovery of function. The collective efforts of several laboratories have established stereo vision as one of the most productive model systems for elucidating the neural basis of perception. Much remains to be learned about how the disparity signals that are initially encoded in primary visual cortex are routed to and processed by extrastriate areas to mediate the diverse capacities of 3D vision that enhance our daily experience of the world. PMID:17978018

  10. Insertion of linear 8.4 μm diameter 16 channel carbon fiber electrode arrays for single unit recordings

    PubMed Central

    Patel, Paras R.; Na, Kyounghwan; Zhang, Huanan; Kozai, Takashi D. Y.; Kotov, Nicholas A.; Yoon, Euisik; Chestek, Cynthia A.

    2016-01-01

    Objective Single carbon fiber electrodes (d=8.4 μm) insulated with parylene-c and functionalized with PEDOT:pTS have been shown to record single unit activity but manual implantation of these devices with forceps can be difficult. Without an improvement in the insertion method any increase in the channel count by fabricating carbon fiber arrays would be impractical. In this study, we utilize a water soluble coating and structural backbones that allow us to create, implant, and record from fully functionalized arrays of carbon fibers with ~150 μm pitch. Approach Two approaches were tested for the insertion of carbon fiber arrays. The first method used a PEG coating that temporarily stiffened the fibers while leaving a small portion at the tip exposed. The small exposed portion (500 μm – 1 mm) readily penetrated the brain allowing for an insertion that did not require the handling of each fiber by forceps. The second method involved the fabrication of silicon support structures with individual shanks spaced 150 μm apart. Each shank consisted of a small groove that held an individual carbon fiber. Main results Our results showed that the PEG coating allowed for the chronic implantation of carbon fiber arrays in 5 rats with unit activity detected at 31 days post-implant. The silicon support structures recorded single unit activity in 3 acute rat surgeries. In one of those surgeries a stacked device with 3 layers of silicon support structures and carbon fibers was built and shown to readily insert into the brain with unit activity on select sites. Significance From these studies we have found that carbon fibers spaced at ~150 μm readily insert into the brain. This greatly increases the recording density of chronic neural probes and paves the way for even higher density devices that have a minimal scarring response. PMID:26035638

  11. Energy efficient neural stimulation: coupling circuit design and membrane biophysics.

    PubMed

    Foutz, Thomas J; Ackermann, D Michael; Kilgore, Kevin L; McIntyre, Cameron C

    2012-01-01

    The delivery of therapeutic levels of electrical current to neural tissue is a well-established treatment for numerous indications such as Parkinson's disease and chronic pain. While the neuromodulation medical device industry has experienced steady clinical growth over the last two decades, much of the core technology underlying implanted pulse generators remain unchanged. In this study we propose some new methods for achieving increased energy-efficiency during neural stimulation. The first method exploits the biophysical features of excitable tissue through the use of a centered-triangular stimulation waveform. Neural activation with this waveform is achieved with a statistically significant reduction in energy compared to traditional rectangular waveforms. The second method demonstrates energy savings that could be achieved by advanced circuitry design. We show that the traditional practice of using a fixed compliance voltage for constant-current stimulation results in substantial energy loss. A portion of this energy can be recuperated by adjusting the compliance voltage to real-time requirements. Lastly, we demonstrate the potential impact of axon fiber diameter on defining the energy-optimal pulse-width for stimulation. When designing implantable pulse generators for energy efficiency, we propose that the future combination of a variable compliance system, a centered-triangular stimulus waveform, and an axon diameter specific stimulation pulse-width has great potential to reduce energy consumption and prolong battery life in neuromodulation devices.

  12. Requirement for Foxd3 in Maintenance of Neural Crest Progenitors

    PubMed Central

    Teng, Lu; Mundell, Nathan A.; Frist, Audrey Y.; Wang, Qiaohong; Labosky, Patricia A.

    2008-01-01

    Summary Understanding the molecular mechanisms of stem cell maintenance is critical for the ultimate goal of manipulating stem cells for treatment of disease. Foxd3 is required early in mouse embryogenesis; Foxd3−/− embryos fail around the time of implantation, cells of the inner cell mass cannot be maintained in vitro, and blastocyst-derived stem cell lines cannot be established. Here, we report that Foxd3 is required for maintenance of the multipotent mammalian neural crest. Using tissue specific deletion of Foxd3 in the neural crest, we show that Foxd3flox/−; Wnt1-Cre mice die perinatally with a catastrophic loss of neural crest-derived structures. Cranial neural crest tissues are either missing or severely reduced in size, the peripheral nervous system consists of reduced dorsal root ganglia and cranial nerves, and the entire gastrointestinal tract is devoid of neural crest derivatives. These results demonstrate a global role for this transcriptional repressor in all aspects of neural crest maintenance along the anterior-posterior axis, and establish an unprecedented molecular link between multiple divergent progenitor lineages of the mammalian embryo. PMID:18367558

  13. Go with the Flow: Cerebrospinal Fluid Flow Regulates Neural Stem Cell Proliferation.

    PubMed

    Kaneko, Naoko; Sawamoto, Kazunobu

    2018-06-01

    Adult neural stem cells in the wall of brain ventricles make direct contact with cerebrospinal fluid. In this issue of Cell Stem Cell, Petrik et al. (2018) demonstrate that these neural stem cells sense the flow of cerebrospinal fluid through a transmembrane sodium channel, ENaC, which regulates their proliferation. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. Exploiting spatial degrees of freedom for high data rate ultrasound communication with implantable devices

    NASA Astrophysics Data System (ADS)

    Wang, Max L.; Arbabian, Amin

    2017-09-01

    We propose and demonstrate an ultrasonic communication link using spatial degrees of freedom to increase data rates for deeply implantable medical devices. Low attenuation and millimeter wavelengths make ultrasound an ideal communication medium for miniaturized low-power implants. While a small spectral bandwidth has drastically limited achievable data rates in conventional ultrasonic implants, a large spatial bandwidth can be exploited by using multiple transducers in a multiple-input/multiple-output system to provide spatial multiplexing gain without additional power, larger bandwidth, or complicated packaging. We experimentally verify the communication link in mineral oil with a transmitter and a receiver 5 cm apart, each housing two custom-designed mm-sized piezoelectric transducers operating at the same frequency. Two streams of data modulated with quadrature phase-shift keying at 125 kbps are simultaneously transmitted and received on both channels, effectively doubling the data rate to 250 kbps with a measured bit error rate below 10-4. We also evaluate the performance and robustness of the channel separation network by testing the communication link after introducing position offsets. These results demonstrate the potential of spatial multiplexing to enable more complex implant applications requiring higher data rates.

  15. Removal of ion-implanted photoresists on GaAs using two organic solvents in sequence

    NASA Astrophysics Data System (ADS)

    Oh, Eunseok; Na, Jihoon; Lee, Seunghyo; Lim, Sangwoo

    2016-07-01

    Organic solvents can effectively remove photoresists on III-V channels without damage or etching of the channel material during the process. In this study, a two-step sequential photoresist removal process using two different organic solvents was developed to remove implanted ArF and KrF photoresists at room temperature. The effects of organic solvents with either low molar volumes or high affinities for photoresists were evaluated to find a proper combination that can effectively remove high-dose implanted photoresists without damaging GaAs surfaces. The performance of formamide, acetonitrile, nitromethane, and monoethanolamine for the removal of ion-implanted ArF and KrF photoresists were compared using a two-step sequential photoresist removal process followed by treatment in dimethyl sulfoxide (DMSO). Among the various combinations, the acetonitrile + DMSO two-step sequence exhibited the best removal of photoresists that underwent ion implantation at doses of 5 × 1013-5 × 1015 atoms/cm2 on both flat and trench-structured GaAs surfaces. The ability of the two-step process using organic solvents to remove the photoresists can be explained by considering the affinities of solvents for a polymer and its permeability through the photoresist.

  16. Chip-scale hermetic feedthroughs for implantable bionics.

    PubMed

    Guenther, Thomas; Dodds, Christopher W D; Lovell, Nigel H; Suaning, Gregg J

    2011-01-01

    Most implantable medical devices such as cochlear implants and visual prostheses require protection of the stimulating electronics. This is achieved by way of a hermetic feedthrough system which typically features three important attributes: biocompatibility with the human body, device hermeticity and density of feedthrough conductors. On the quest for building a visual neuroprosthesis, a high number of stimulating channels is required. This has encouraged new technologies with higher rates of production yield and further miniaturization. An Al(2)O(3) based feedthrough system has been developed comprising up to 20 platinum feedthroughs per square millimeter. Ceramics substrates are shown to have leak rates below 1 × 10(-12) atm × cc/s, thus exceeding the resolution limits of most commercially available leak detectors. A sheet resistance of 0.05 Ω can be achieved. This paper describes the design, fabrication process and hermeticity testing of high density feedthroughs for use in neuroprosthetic implants.

  17. Rapid evaluation of the durability of cortical neural implants using accelerated aging with reactive oxygen species

    PubMed Central

    Takmakov, Pavel; Ruda, Kiersten; Phillips, K Scott; Isayeva, Irada S; Krauthamer, Victor; Welle, Cristin G

    2017-01-01

    Objective A challenge for implementing high bandwidth cortical brain–machine interface devices in patients is the limited functional lifespan of implanted recording electrodes. Development of implant technology currently requires extensive non-clinical testing to demonstrate device performance. However, testing the durability of the implants in vivo is time-consuming and expensive. Validated in vitro methodologies may reduce the need for extensive testing in animal models. Approach Here we describe an in vitro platform for rapid evaluation of implant stability. We designed a reactive accelerated aging (RAA) protocol that employs elevated temperature and reactive oxygen species (ROS) to create a harsh aging environment. Commercially available microelectrode arrays (MEAs) were placed in a solution of hydrogen peroxide at 87 °C for a period of 7 days. We monitored changes to the implants with scanning electron microscopy and broad spectrum electrochemical impedance spectroscopy (1 Hz–1 MHz) and correlated the physical changes with impedance data to identify markers associated with implant failure. Main results RAA produced a diverse range of effects on the structural integrity and electrochemical properties of electrodes. Temperature and ROS appeared to have different effects on structural elements, with increased temperature causing insulation loss from the electrode microwires, and ROS concentration correlating with tungsten metal dissolution. All array types experienced impedance declines, consistent with published literature showing chronic (>30 days) declines in array impedance in vivo. Impedance change was greatest at frequencies <10 Hz, and smallest at frequencies 1 kHz and above. Though electrode performance is traditionally characterized by impedance at 1 kHz, our results indicate that an impedance change at 1 kHz is not a reliable predictive marker of implant degradation or failure. Significance ROS, which are known to be present in vivo, can create

  18. A retrospective study on related factors affecting the survival rate of dental implants

    PubMed Central

    Kang, Jeong-Kyung; Lee, Ki; Lee, Yong-Sang; Park, Pil-Kyoo

    2011-01-01

    PURPOSE The aim of this retrospective study is to analyze the relationship between local factors and survival rate of dental implant which had been installed and restored in Seoul Veterans Hospital dental center for past 10 years. And when the relationship is found out, it could be helpful to predict the prognosis of dental implants. MATERIALS AND METHODS A retrospective study of patients receiving root-shaped screw-type dental implants placed from January 2000 to December 2009 was conducted. 6385 implants were placed in 3755 patients. The following data were collected from the dental records and radiographs: patient's age, gender, implant type and surface, length, diameter, location of implant placement, bone quality, prosthesis type. The correlations between these data and survival rate were analyzed. Statistical analysis was performed with the use of Kaplan-Meier analysis, Chi-square test and odds ratio. RESULTS In all, 6385 implants were placed in 3755 patients (3120 male, 635 female; mean age 65 ± 10.58 years). 108 implants failed and the cumulative survival rate was 96.33%. There were significant differences in age, implant type and surface, length, location and prosthesis type (P<.05). No significant differences were found in relation to the following factors: gender, diameter and bone quality (P>.05). CONCLUSION Related factors such as age, implant type, length, location and prosthesis type had a significant effect on the implant survival. PMID:22259704

  19. High-Density Stretchable Electrode Grids for Chronic Neural Recording.

    PubMed

    Tybrandt, Klas; Khodagholy, Dion; Dielacher, Bernd; Stauffer, Flurin; Renz, Aline F; Buzsáki, György; Vörös, János

    2018-04-01

    Electrical interfacing with neural tissue is key to advancing diagnosis and therapies for neurological disorders, as well as providing detailed information about neural signals. A challenge for creating long-term stable interfaces between electronics and neural tissue is the huge mechanical mismatch between the systems. So far, materials and fabrication processes have restricted the development of soft electrode grids able to combine high performance, long-term stability, and high electrode density, aspects all essential for neural interfacing. Here, this challenge is addressed by developing a soft, high-density, stretchable electrode grid based on an inert, high-performance composite material comprising gold-coated titanium dioxide nanowires embedded in a silicone matrix. The developed grid can resolve high spatiotemporal neural signals from the surface of the cortex in freely moving rats with stable neural recording quality and preserved electrode signal coherence during 3 months of implantation. Due to its flexible and stretchable nature, it is possible to minimize the size of the craniotomy required for placement, further reducing the level of invasiveness. The material and device technology presented herein have potential for a wide range of emerging biomedical applications. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Effect of tungsten implantation on the switching parameters in V2O5 films

    NASA Astrophysics Data System (ADS)

    Burdyukh, S. V.; Berezina, O. Ya.; Pergament, A. L.

    2017-11-01

    The paper examines the effect of doping with tungsten on switching in hydrated vanadium pentoxide films. The switching effect is associated with the metal-insulator transition in a vanadium dioxide channel that forms in the initial film due to the process of electrical forming (EF). Doping is carried out by the plasma immersion ion implantation method. It is shown that implanting small tungsten doses improves the switching parameters after EF. When implanting large doses, switching is observed without EF, and if EF is applied, the switching effect, on the contrary, disappears.

  1. Development and Evaluation of Micro-Electrocorticography Arrays for Neural Interfacing Applications

    NASA Astrophysics Data System (ADS)

    Schendel, Amelia Ann

    Neural interfaces have great promise for both electrophysiological research and therapeutic applications. Whether for the study of neural circuitry or for neural prosthetic or other therapeutic applications, micro-electrocorticography (micro-ECoG) arrays have proven extremely useful as neural interfacing devices. These devices strike a balance between invasiveness and signal resolution, an important step towards eventual human application. The objective of this research was to make design improvements to micro-ECoG devices to enhance both biocompatibility and device functionality. To best evaluate the effectiveness of these improvements, a cranial window imaging method for in vivo monitoring of the longitudinal tissue response post device implant was developed. Employment of this method provided valuable insight into the way tissue grows around micro-ECoG arrays after epidural implantation, spurring a study of the effects of substrate geometry on the meningeal tissue response. The results of the substrate footprint comparison suggest that a more open substrate geometry provides an easy path for the tissue to grow around to the top side of the device, whereas a solid device substrate encourages the tissue to thicken beneath the device, between the electrode sites and the brain. The formation of thick scar tissue between the recording electrode sites and the neural tissue is disadvantageous for long-term recorded signal quality, and thus future micro-ECoG device designs should incorporate open-architecture substrates for enhanced longitudinal in vivo function. In addition to investigating improvements for long-term device reliability, it was also desired to enhance the functionality of micro-ECoG devices for neural electrophysiology research applications. To achieve this goal, a completely transparent graphene-based device was fabricated for use with the cranial window imaging method and optogenetic techniques. The use of graphene as the conductive material provided

  2. Chitosan derived co-spheroids of neural stem cells and mesenchymal stem cells for neural regeneration.

    PubMed

    Han, Hao-Wei; Hsu, Shan-Hui

    2017-10-01

    Chitosan has been considered as candidate biomaterials for neural applications. The effective treatment of neurodegeneration or injury to the central nervous system (CNS) is still in lack nowadays. Adult neural stem cells (NSCs) represents a promising cell source to treat the CNS diseases but they are limited in number. Here, we developed the core-shell spheroids of NSCs (shell) and mesenchymal stem cells (MSCs, core) by co-culturing cells on the chitosan surface. The NSCs in chitosan derived co-spheroids displayed a higher survival rate than those in NSC homo-spheroids. The direct interaction of NSCs with MSCs in the co-spheroids increased the Notch activity and differentiation tendency of NSCs. Meanwhile, the differentiation potential of MSCs in chitosan derived co-spheroids was significantly enhanced toward neural lineages. Furthermore, NSC homo-spheroids and NSC/MSC co-spheroids derived on chitosan were evaluated for their in vivo efficacy by the embryonic and adult zebrafish brain injury models. The locomotion activity of zebrafish receiving chitosan derived NSC homo-spheroids or NSC/MSC co-spheroids was partially rescued in both models. Meanwhile, the higher survival rate was observed in the group of adult zebrafish implanted with chitosan derived NSC/MSC co-spheroids as compared to NSC homo-spheroids. These evidences indicate that chitosan may provide an extracellular matrix-like environment to drive the interaction and the morphological assembly between NSCs and MSCs and promote their neural differentiation capacities, which can be used for neural regeneration. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Auditory cortical responses in patients with cochlear implants

    PubMed Central

    Burdo, S; Razza, S; Di Berardino, F; Tognola, G

    2006-01-01

    Summary Currently, the most commonly used electrophysiological tests for cochlear implant evaluation are Averaged Electrical Voltages (AEV), Electrical Advisory Brainstem Responses (EABR) and Neural Response Telemetry (NRT). The present paper focuses on the study of acoustic auditory cortical responses, or slow vertex responses, which are not widely used due to the difficulty in recording, especially in young children. Aims of this study were validation of slow vertex responses and their possible applications in monitoring postimplant results, particularly restoration of hearing and auditory maturation. In practice, the use of tone-bursts, also through hearing aids or cochlear implants, as in slow vertex responses, allows many more frequencies to be investigated and louder intensities to be reached than with other tests based on a click as stimulus. Study design focused on latencies of N1 and P2 slow vertex response peaks in cochlear implants. The study population comprised 45 implant recipients (aged 2 to 70 years), divided into 5 different homogeneous groups according to chronological age, age at onset of deafness, and age at implantation. For each subject, slow vertex responses and free-field auditory responses (PTAS) were recorded for tone-bursts at 500 and 2000 Hz before cochlear implant surgery (using hearing aid amplification) and during scheduled sessions at 3rd and 12th month after implant activation. Results showed that N1 and P2 latencies decreased in all groups starting from 3rd through 12th month after activation. Subjects implanted before school age or at least before age 8 yrs showed the widest latency changes. All subjects showed a reduction in the gap between subjective thresholds (obtained with free field auditory responses) and objective thresholds (obtained with slow vertex responses), obtained in presurgery stage and after cochlear implant. In conclusion, a natural evolution of neurophysiological cortical activities of the auditory pathway

  4. Comparison of marginal bone loss and implant success between axial and tilted implants in maxillary All-on-4 treatment concept rehabilitations after 5 years of follow-up.

    PubMed

    Hopp, Milena; de Araújo Nobre, Miguel; Maló, Paulo

    2017-10-01

    There is need for more scientific and clinical information on longer-term outcomes of tilted implants compared to implants inserted in an axial position. Comparison of marginal bone loss and implant success after a 5-year follow-up between axial and tilted implants inserted for full-arch maxillary rehabilitation. The retrospective clinical study included 891 patients with 3564 maxillary implants rehabilitated according to the All-on-4 treatment concept. The follow-up time was 5 years. Linear mixed-effect models were performed to analyze the influence of implant orientation (axial/tilted) on marginal bone loss and binary logistic regression to assess the effect of patient characteristics on occurrence of marginal bone loss >2.8 mm. Only those patients with measurements of at least one axial and one tilted implant available were analyzed. This resulted in a data set of 2379 implants (1201 axial, 1178 tilted) in 626 patients (=reduced data set). Axial and tilted implants showed comparable mean marginal bone losses of 1.14 ± 0.71 and 1.19 ± 0.82 mm, respectively. Mixed model analysis indicated that marginal bone loss levels at 5 years follow up was not significantly affected by the orientation (axial/tilted) of the implants in the maxillary bone. Smoking and female gender were associated with marginal bone loss >2.8 mm in a logistic regression analysis. Five-year implant success rates were 96%. The occurrence of implant failure showed to be statistically independent from orientation. Within the limitations of this study and considering a follow-up time of 5 years, it can be concluded that tilted implants behave similarly with regards to marginal bone loss and implant success in comparison to axial implants in full-arch rehabilitation of the maxilla. Longer-term outcomes (10 years +) are needed to verify this result. © 2017 Wiley Periodicals, Inc.

  5. Prognosis of Combining Remaining Teeth and Implants in Double-Crown-Retained Removable Dental Prostheses: A Systematic Review and Meta-Analysis.

    PubMed

    Lian, Meifei; Zhao, Kai; Feng, Yunzhi; Yao, Qian

    The reliability of combining natural teeth and implants in one removable prosthesis is controversial. This systematic review was conducted to evaluate the prognosis of combined tooth/implant-supported double-crown-retained removable dental prostheses (DCR-RDPs) and to compare them with solely implant-supported prostheses with a minimum observation period of 3 years. Electronic database (PubMed, Embase, Central, and SCI) and manual searches up to August 2016 were conducted to identify human clinical studies on tooth/implant-supported DCR-RDPs. Literature selection and data extraction were accomplished by two independent reviewers. Meta-analyses of survival and complication rates were performed separately for combined tooth/implant-supported and solely implant-supported DCRRDPs. Among the initially identified 366 articles, 17 were included in a quantitative analysis. The estimated overall cumulative survival rate (CSR) for implants in combined tooth/implant-supported DCRRDPs was 98.72% (95% confidence interval [95% CI]: 96.98% to 99.82%), and that for implants in solely implant-supported DCR-RDPs was 98.83% (95% CI: 97.45% to 99.75%). The summary CSR for abutment teeth was 92.96% (95% CI: 85.38% to 98.12%). Double-crown-retained dentures with both abutment types showed high CSRs, most of which were approximately 100%. Regarding prosthetic maintenance treatment, the estimated incidence for patients treated with combined tooth/implant-supported RDPs was 0.164 (95% CI: 0.089 to 0.305) per patient per year (T/P/Y) and that for patients restored with solely implant-supported RDPs was 0.260 (95% CI: 0.149 to 0.454) T/P/Y. Based on four studies with combined tooth/implant-supported DCR-RDPs, no intrusion phenomena were encountered. Subject to the limitations of the present review, combining remaining teeth and implants in DCR-RDPs is a reliable and predictable treatment modality for partially edentulous patients. Comparable high survival rates and minor biologic or

  6. In vivo operation of the Boston 15-channel wireless subretinal visual prosthesis

    NASA Astrophysics Data System (ADS)

    Shire, Douglas B.; Doyle, Patrick; Kelly, Shawn K.; Gingerich, Marcus D.; Chen, Jinghua; Cogan, Stuart F.; Drohan, William A.; Mendoza, Oscar; Theogarajan, Luke; Wyatt, John; Rizzo, Joseph F.

    2010-02-01

    This presentation concerns the engineering development of the Boston visual prosthesis for restoring useful vision to patients blind with degenerative retinal disease. A miniaturized, hermetically-encased, 15-channel wirelessly-operated retinal prosthetic was developed for implantation and pre-clinical studies in Yucatan mini-pig animal models. The prosthesis conforms to the eye and drives a microfabricated polyimide stimulating electrode array having sputtered iridium oxide electrodes. This array is implanted into the subretinal space using a specially-designed ab externo surgical technique; the bulk of the prosthesis is on the surface of the sclera. The implanted device includes a hermetic titanium case containing a 15-channel stimulator chip; secondary power/data receiving coils surround the cornea. Long-term in vitro pulse testing was also performed on the electrodes to ensure their stability over years of operation. Assemblies were first tested in vitro to verify wireless operation of the system in biological saline using a custom RF transmitter circuit and primary coils. Stimulation pulse strength, duration and frequency were programmed wirelessly using a computer with a custom graphical user interface. Operation of the retinal implant was verified in vivo in 3 minipigs for more than three months by measuring stimulus artifacts on the eye surface using contact lens electrodes.

  7. Massively parallel neural circuits for stereoscopic color vision: encoding, decoding and identification.

    PubMed

    Lazar, Aurel A; Slutskiy, Yevgeniy B; Zhou, Yiyin

    2015-03-01

    Past work demonstrated how monochromatic visual stimuli could be faithfully encoded and decoded under Nyquist-type rate conditions. Color visual stimuli were then traditionally encoded and decoded in multiple separate monochromatic channels. The brain, however, appears to mix information about color channels at the earliest stages of the visual system, including the retina itself. If information about color is mixed and encoded by a common pool of neurons, how can colors be demixed and perceived? We present Color Video Time Encoding Machines (Color Video TEMs) for encoding color visual stimuli that take into account a variety of color representations within a single neural circuit. We then derive a Color Video Time Decoding Machine (Color Video TDM) algorithm for color demixing and reconstruction of color visual scenes from spikes produced by a population of visual neurons. In addition, we formulate Color Video Channel Identification Machines (Color Video CIMs) for functionally identifying color visual processing performed by a spiking neural circuit. Furthermore, we derive a duality between TDMs and CIMs that unifies the two and leads to a general theory of neural information representation for stereoscopic color vision. We provide examples demonstrating that a massively parallel color visual neural circuit can be first identified with arbitrary precision and its spike trains can be subsequently used to reconstruct the encoded stimuli. We argue that evaluation of the functional identification methodology can be effectively and intuitively performed in the stimulus space. In this space, a signal reconstructed from spike trains generated by the identified neural circuit can be compared to the original stimulus. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. River channel adjustments in Southern Italy over the past 150 years and implications for channel recovery

    NASA Astrophysics Data System (ADS)

    Scorpio, Vittoria; Aucelli, Pietro P. C.; Giano, Salvatore I.; Pisano, Luca; Robustelli, Gaetano; Rosskopf, Carmen M.; Schiattarella, Marcello

    2015-12-01

    Multi-temporal GIS analysis of topographic maps and aerial photographs along with topographic and geomorphological surveys are used to assess evolutionary trends and key control factors of channel adjustments for five major rivers in southern Italy (the Trigno, Biferno, Volturno, Sinni and Crati rivers) to support assessment of channel recovery and river restoration. Three distinct phases of channel adjustment are identified over the past 150 years primarily driven by human disturbances. Firstly, slight channel widening dominated from the last decades of the nineteenth century to the 1950s. Secondly, from the 1950s to the end of the 1990s, altered sediment fluxes induced by in-channel mining and channel works brought about moderate to very intense incision (up to 6-7 m) accompanied by strong channel narrowing (up to 96%) and changes in channel configuration from multi-threaded to single-threaded patterns. Thirdly, the period from around 2000 to 2015 has been characterized by channel stabilization and local widening. Evolutionary trajectories of the rivers studied are quite similar to those reconstructed for other Italian rivers, particularly regarding the second phase of channel adjustments and ongoing transitions towards channel recovery in some reaches. Analyses of river dynamics, recovery potential and connectivity with sediment sources of the study reaches, framed in their catchment context, can be used as part of a wider interdisciplinary approach that views effective river restoration alongside sustainable and risk-reduced river management.

  9. Enhancing the Performance of Medical Implant Communication Systems through Cooperative Diversity

    PubMed Central

    Hegyi, Barnabás; Levendovszky, János

    2010-01-01

    Battery-operated medical implants—such as pacemakers or cardioverter-defibrillators—have already been widely used in practical telemedicine and telecare applications. However, no solution has yet been found to mitigate the effect of the fading that the in-body to off-body communication channel is subject to. In this paper, we reveal and assess the potential of cooperative diversity to combat fading—hence to improve system performance—in medical implant communication systems. In the particular cooperative communication scenario we consider, multiple cooperating receiver units are installed across the room accommodating the patient with a medical implant inside his/her body. Our investigations have shown that the application of cooperative diversity is a promising approach to enhance the performance of medical implant communication systems in various aspects such as implant lifetime and communication link reliability. PMID:20379346

  10. Factors associated with dental implant survival: a 4-year retrospective analysis.

    PubMed

    Zupnik, Jamie; Kim, Soo-woo; Ravens, Daniel; Karimbux, Nadeem; Guze, Kevin

    2011-10-01

    Dental implants are a predictable treatment option for replacing missing teeth and have strong survival and success outcomes. However, previous research showed a wide array of potential risk factors that may have contributed to dental implant failures. The objectives of this study are to study if implant survival rates were affected by known risk factors and risk indicators that may have contributed to implant failures. The secondary outcome measures were whether the level of expertise of the periodontal residents affected success rates and how the rate of implant success at the Harvard School of Dental Medicine (HSDM) compared to published standards. A retrospective chart review of patients at the HSDM who had one of two types of rough-surface implants (group A or B) placed by periodontology residents from 2003 to 2006 was performed. Demographic, health, and implant data were collected and analyzed by multimodel analyses to determine failure rates and any factors that may have increased the likelihood of an implant failure. The study cohort included 341 dental implants. The odds ratio for an implant failure was most clearly elevated for diabetes (2.59 implant surface group B (7.84), and male groups (4.01). There was no significant difference regarding the resident experience. The success rate for HSDM periodontology residents was 96.48% during the 4-year study period. This study demonstrates that implant success rates at HSDM fell within accepted published standards, confirmed previously identified risk factors for a failure, and potentially suggested that other acknowledged risk factors could be controlled for. Furthermore, the level of experience of the periodontology resident did not have an impact on survival outcomes.

  11. Reliable and energy-efficient communications for wireless biomedical implant systems.

    PubMed

    Ntouni, Georgia D; Lioumpas, Athanasios S; Nikita, Konstantina S

    2014-11-01

    Implant devices are used to measure biological parameters and transmit their results to remote off-body devices. As implants are characterized by strict requirements on size, reliability, and power consumption, applying the concept of cooperative communications to wireless body area networks offers several benefits. In this paper, we aim to minimize the power consumption of the implant device by utilizing on-body wearable devices, while providing the necessary reliability in terms of outage probability and bit error rate. Taking into account realistic power considerations and wireless propagation environments based on the IEEE P802.l5 channel model, an exact theoretical analysis is conducted for evaluating several communication scenarios with respect to the position of the wearable device and the motion of the human body. The derived closed-form expressions are employed toward minimizing the required transmission power, subject to a minimum quality-of-service requirement. In this way, the complexity and power consumption are transferred from the implant device to the on-body relay, which is an efficient approach since they can be easily replaced, in contrast to the in-body implants.

  12. Electrochemical Deposition of Nanostructured Conducting Polymer Coatings on Neural Prosthetic Devices

    NASA Astrophysics Data System (ADS)

    Yang, Junyan; Martin, David

    2003-03-01

    Micromachined neural prosthetic devices facilitate the functional stimulation of and recording from the central nervous system (CNS). These devices have been fabricated to consist of silicon shanks that have gold or iridium sites along their surface. Our goal is to improve the biocompatibility and long-term performance of the neural prosthetic probes when they are implanted chronically in the brain. In our most recent efforts we have established that electrochemical polymerization can be used to deposit fuzzy coatings of conducting polymers specifically on the electrode sites. For neural prosthetic devices that are intended for long term implantation, we need to develop surfaces that provide intimate contact and promote efficient signal transport at the interface of the microelectrode array and brain tissue. We have developed methods to rapidly and reliably fabricate nanostructured conducting polymer coatings on the electrode probes using templated and surfactant-mediated techniques. Conducting polymer nanomushrooms and nanohairs of polypyrrole (PPy) were electrochemically polymerized onto the functional sites of neural probes by using either nanoporous block copolymers thin films, "track-etched" polycarbonate films or anodic aluminium oxide membranes as templates. Nanofibers of conducting polymers have also been successfully obtained by polymerizations in the presence of surfactants. The influence of current density, monomer concentration, surfactant concentration, and deposition charge on the thickness and morphology of the nanostructured conducting polymer coatings has been studied by optical, scanned probe, scanning electron and transmission electron microscopy. As compared with the normal nodular morphology of polypyrrole, the nanostructured morphologies grown from the neural electrode result in fuzzy coatings with extremely high surface area. The electrical properties of the polymer coatings were studied by Impedance Spectroscopy (IS) and Cyclic Voltammetry

  13. A TinyOS-based wireless neural interface.

    PubMed

    Farshchi, Shahin; Mody, Istvan; Judy, Jack W

    2004-01-01

    The overlay of a neural interface upon a TinyOS-based sensing and communication platform is described. The system amplifies, digitally encodes, and transmits two EEG channels of neural signals from an un-tethered subject to a remote gateway, which routes the signals to a client PC. This work demonstrates the viability of the TinyOS-based sensor technology as a foundation for chronic remote biological monitoring applications, and thus provides an opportunity to create a system that can leverage from the frequent networking and communications advancements being made by the global TinyOS-development community.

  14. A synthetic bioactive resorbable graft for predictable implant reconstruction: part one.

    PubMed

    Valen, Maurice; Ganz, Scott D

    2002-01-01

    Animal studies were conducted to evaluate the cell response and chemical potentiality of a synthetic bioactive resorbable graft (SBRG) made of nonceramic cluster particulate of low-temperature HA material. The study evaluated bone-bridging of the SBRG particulates in 1-mm wide implant channels of 5 x 8 mm long roughened titanium interface in 6 dogs and compared results to the same implant channels left empty as controls at 6- and 12-week intervals. Resorption rate capacity and cell response were evaluated with an assessment of the chemical characterization of the synthetic nonceramic material next to the titanium implant interfaces. Results of the animal studies were compared with human histologic biopsies of the SBRG for bone quality, density, and bone growth into defect sites concurrent with resorption time of the graft. One human biopsy consisted of a graft mixture of the SBRG and dense bovine-derived HA, compared under the electron microscope, including histology by H and E staining. Part 1 of this paper presents evidence of the predictability and efficacy of the SBRG osteoconductive, particulate chemical potentiality to aid in the regeneration of lost bone anatomy next to titanium implant interfaces. Recent technological innovations in computer hardware and software have given clinicians the tools to determine 3-dimensional quality and density of bone, including anatomical discrepancies, which can aid in the diagnosis and treatment planning for grafting procedures. When teeth are extracted, the surrounding bone and soft tissue are challenged as a result of the natural resorptive process. The diminished structural foundation for prosthetic reconstruction, with or without implants, can be compromised. A synthetic bioactive resorbable graft material having osteoconductive biochemical and biomechanical qualities similar to the host bone provides the means to improve compromised bone topography for ridge preservation, ridge augmentation, or to enhance the bony site

  15. An Implanted, Stimulated Muscle Powered Piezoelectric Generator

    NASA Technical Reports Server (NTRS)

    Lewandowski, Beth; Gustafson, Kenneth; Kilgore, Kevin

    2007-01-01

    A totally implantable piezoelectric generator system able to harness power from electrically activated muscle could be used to augment the power systems of implanted medical devices, such as neural prostheses, by reducing the number of battery replacement surgeries or by allowing periods of untethered functionality. The features of our generator design are no moving parts and the use of a portion of the generated power for system operation and regulation. A software model of the system has been developed and simulations have been performed to predict the output power as the system parameters were varied within their constraints. Mechanical forces that mimic muscle forces have been experimentally applied to a piezoelectric generator to verify the accuracy of the simulations and to explore losses due to mechanical coupling. Depending on the selection of system parameters, software simulations predict that this generator concept can generate up to approximately 700 W of power, which is greater than the power necessary to drive the generator, conservatively estimated to be 50 W. These results suggest that this concept has the potential to be an implantable, self-replenishing power source and further investigation is underway.

  16. Search for the standard model higgs Boson in the ZH-->nunubb channel in 5.2 fb{-1} of pp collisions at sqrt[s]=1.96 TeV.

    PubMed

    Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Ancu, L S; Aoki, M; Arnoud, Y; Arov, M; Askew, A; Asman, B; Atramentov, O; Avila, C; Backusmayes, J; Badaud, F; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Barberis, E; Barfuss, A-F; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Blazey, G; Blessing, S; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Boos, E E; Borissov, G; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Bu, X B; Buchholz, D; Buehler, M; Buescher, V; Bunichev, V; Burdin, S; Burnett, T H; Buszello, C P; Calfayan, P; Calpas, B; Calvet, S; Camacho-Pérez, E; Cammin, J; Carrasco-Lizarraga, M A; Carrera, E; Casey, B C K; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Cheu, E; Chevalier-Théry, S; Cho, D K; Cho, S W; Choi, S; Choudhary, B; Christoudias, T; Cihangir, S; Claes, D; Clutter, J; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Cutts, D; Cwiok, M; Das, A; Davies, G; De, K; de Jong, S J; De La Cruz-Burelo, E; Devaughan, K; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dorland, T; Dubey, A; Dudko, L V; Duflot, L; Duggan, D; Duperrin, A; Dutt, S; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Evans, H; Evdokimov, A; Evdokimov, V N; Facini, G; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fortner, M; Fox, H; Fuess, S; Gadfort, T; Galea, C F; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Geng, W; Gerbaudo, D; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Golovanov, G; Gómez, B; Goussiou, A; Grannis, P D; Greder, S; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, F; Guo, J; Gutierrez, G; Gutierrez, P; Haas, A; Haefner, P; Hagopian, S; Haley, J; Hall, I; Han, L; Harder, K; Harel, A; Hauptman, J M; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinson, A P; Heintz, U; Hensel, C; Heredia-De La Cruz, I; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hoang, T; Hobbs, J D; Hoeneisen, B; Hohlfeld, M; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Huske, N; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jamin, D; Jesik, R; Johns, K; Johnson, C; Johnson, M; Johnston, D; Jonckheere, A; Jonsson, P; Juste, A; Kajfasz, E; Karmanov, D; Kasper, P A; Katsanos, I; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y N; Khatidze, D; Kirby, M H; Kirsch, M; Kohli, J M; Kozelov, A V; Kraus, J; Kumar, A; Kupco, A; Kurca, T; Kuzmin, V A; Kvita, J; Lam, D; Lammers, S; Landsberg, G; Lebrun, P; Lee, H S; Lee, W M; Leflat, A; Lellouch, J; Li, L; Li, Q Z; Lietti, S M; Lim, J K; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobodenko, A; Lokajicek, M; Love, P; Lubatti, H J; Luna-Garcia, R; Lyon, A L; Maciel, A K A; Mackin, D; Mättig, P; Magaña-Villalba, R; Mal, P K; Malik, S; Malyshev, V L; Maravin, Y; Martínez-Ortega, J; McCarthy, R; McGivern, C L; Meijer, M M; Melnitchouk, A; Mendoza, L; Menezes, D; Mercadante, P G; Merkin, M; Meyer, A; Meyer, J; Mommsen, R K; Mondal, N K; Moulik, T; Muanza, G S; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Nayyar, R; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Nogima, H; Novaes, S F; Nunnemann, T; Obrant, G; Ochando, C; Onoprienko, D; Orduna, J; Osman, N; Osta, J; Otec, R; Otero Y Garzón, G J; Owen, M; Padilla, M; Padley, P; Pangilinan, M; Parashar, N; Parihar, V; Park, S-J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Penning, B; Perfilov, M; Peters, K; Peters, Y; Pétroff, P; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M; Pol, M-E; Polozov, P; Popov, A V; Prewitt, M; Price, D; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rangel, M S; Ranjan, K; Ratoff, P N; Razumov, I; Renkel, P; Rich, P; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rominsky, M; Royon, C; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Sanghi, B; Savage, G; Sawyer, L; Scanlon, T; Schaile, D; Schamberger, R D; Scheglov, Y; Schellman, H; Schliephake, T; Schlobohm, S; Schwanenberger, C; Schwienhorst, R; Sekaric, J; Severini, H; Shabalina, E; Shary, V; Shchukin, A A; Shivpuri, R K; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Spurlock, B; Stark, J; Stolin, V; Stoyanova, D A; Strandberg, J; Strang, M A; Strauss, E; Strauss, M; Ströhmer, R; Strom, D; Stutte, L; Svoisky, P; Takahashi, M; Tanasijczuk, A; Taylor, W; Tiller, B; Titov, M; Tokmenin, V V; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, L; Uvarov, S; Uzunyan, S; van den Berg, P J; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vasilyev, I A; Verdier, P; Vertogradov, L S; Verzocchi, M; Vesterinen, M; Vilanova, D; Vint, P; Vokac, P; Wahl, H D; Wang, M H L S; Warchol, J; Watts, G; Wayne, M; Weber, G; Weber, M; Wetstein, M; White, A; Wicke, D; Williams, M R J; Wilson, G W; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Xu, C; Yacoob, S; Yamada, R; Yang, W-C; Yasuda, T; Yatsunenko, Y A; Ye, Z; Yin, H; Yip, K; Yoo, H D; Youn, S W; Yu, J; Zeitnitz, C; Zelitch, S; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zivkovic, L; Zutshi, V; Zverev, E G

    2010-02-19

    A search is performed for the standard model Higgs boson in 5.2 fb{-1} of pp collisions at sqrt[s]=1.96 TeV, collected with the D0 detector at the Fermilab Tevatron Collider. The final state considered is a pair of b jets and large missing transverse energy, as expected from pp-->ZH-->nunubb production. The search is also sensitive to the WH-->lnubb channel when the charged lepton is not identified. For a Higgs boson mass of 115 GeV, a limit is set at the 95% C.L. on the cross section multiplied by branching fraction for [pp-->(Z/W)H](H-->bb) that is a factor of 3.7 larger than the standard model value, consistent with the factor of 4.6 expected.

  17. D Coordinate Transformation Using Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Konakoglu, B.; Cakır, L.; Gökalp, E.

    2016-10-01

    Two coordinate systems used in Turkey, namely the ED50 (European Datum 1950) and ITRF96 (International Terrestrial Reference Frame 1996) coordinate systems. In most cases, it is necessary to conduct transformation from one coordinate system to another. The artificial neural network (ANN) is a new method for coordinate transformation. One of the biggest advantages of the ANN is that it can determine the relationship between two coordinate systems without a mathematical model. The aim of this study was to investigate the performances of three different ANN models (Feed Forward Back Propagation (FFBP), Cascade Forward Back Propagation (CFBP) and Radial Basis Function Neural Network (RBFNN)) with regard to 2D coordinate transformation. To do this, three data sets were used for the same study area, the city of Trabzon. The coordinates of data sets were measured in the ED50 and ITRF96 coordinate systems by using RTK-GPS technique. Performance of each transformation method was investigated by using the coordinate differences between the known and estimated coordinates. The results showed that the ANN algorithms can be used for 2D coordinate transformation in cases where optimum model parameters are selected.

  18. Hexadecameric structure of an invertebrate gap junction channel.

    PubMed

    Oshima, Atsunori; Matsuzawa, Tomohiro; Murata, Kazuyoshi; Tani, Kazutoshi; Fujiyoshi, Yoshinori

    2016-03-27

    Innexins are invertebrate-specific gap junction proteins with four transmembrane helices. These proteins oligomerize to constitute intercellular channels that allow for the passage of small signaling molecules associated with neural and muscular electrical activity. In contrast to the large number of structural and functional studies of connexin gap junction channels, few structural studies of recombinant innexin channels are reported. Here we show the three-dimensional structure of two-dimensionally crystallized Caenorhabditis elegans innexin-6 (INX-6) gap junction channels. The N-terminal deleted INX-6 proteins are crystallized in lipid bilayers. The three-dimensional reconstruction determined by cryo-electron crystallography reveals that a single INX-6 gap junction channel comprises 16 subunits, a hexadecamer, in contrast to chordate connexin channels, which comprise 12 subunits. The channel pore diameters at the cytoplasmic entrance and extracellular gap region are larger than those of connexin26. Two bulb densities are observed in each hemichannel, one in the pore and the other at the cytoplasmic side of the hemichannel in the channel pore pathway. These findings imply a structural diversity of gap junction channels among multicellular organisms. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. EAO Supplement Working Group 4 - EAO CC 2015 Short implants versus sinus lifting with longer implants to restore the posterior maxilla: a systematic review.

    PubMed

    Thoma, D S; Zeltner, M; Hüsler, J; Hämmerle, C H F; Jung, R E

    2015-09-01

    To compare short implants in the posterior maxilla to longer implants placed after or simultaneously with sinus floor elevation procedures. The focused question was as follows: Are short implants superior to longer implants in the augmented sinus in terms of survival and complication rates of implants and reconstructions, patient-reported outcome measures (PROMs) and costs? A MEDLINE search (1990-2014) was performed for randomized controlled clinical studies comparing short implants (≤8 mm) to longer implants (>8 mm) in augmented sinus. The search was complimented by an additional hand search of the selected papers and reviews published between 2011 and 2014. Eligible studies were selected based on the inclusion criteria, and quality assessments were conducted. Descriptive statistics were applied for a number of outcome measures. Survival rates of dental implants were pooled simply in case of comparable studies. Eight randomized controlled clinical trials (RCTs) comparing short implants versus longer implants in the augmented sinus derived from an initial search count of 851 titles were selected and data extracted. In general, all studies were well conducted with a low risk of bias for the majority of the analyzed parameters. Based on the pooled analyses of longer follow-ups (5 studies, 16-18 months), the survival rate of longer implants amounted to 99.5% (95% CI: 97.6-99.98%) and for shorter implants to 99.0% (95% CI: 96.4-99.8%). For shorter follow-ups (3 studies, 8-9 months), the survival rates of longer implants are 100% (95% CI: 97.1-100%) and for shorter implants 98.2% (95% CI: 93.9-99.7%). Complications were predominantly of biological origin, mainly occurred intraoperatively as membrane perforations, and were almost three times as higher for longer implant in the augmented sinus compared to shorter implants. PROMs, morbidity, surgical time and costs were generally in favor of shorter dental implants. All studies were performed by surgeons in specialized

  20. Pediatric cochlear implants: additional disabilities prevalence, risk factors, and effect on language outcomes.

    PubMed

    Birman, Catherine S; Elliott, Elizabeth J; Gibson, William P R

    2012-10-01

    To determine the prevalence of additional disabilities in a pediatric cochlear population, to identify medical and radiologic conditions associated with additional disabilities, and to identify the effect of additional disabilities on speech perception and language at 12 months postoperatively. Retrospective case review. Tertiary referral center and cochlear implant program. Records were reviewed for children 0 to 16 years old inclusive, who had cochlear implant-related operations over a 12-month period. Diagnostic and rehabilitative. Additional disabilities prevalence; medical history and radiologic abnormalities; and the effect on Categories of Auditory Performance (CAP) score at 12 months postoperatively. Eighty-eight children having 96 operations were identified. The overall prevalence of additional disabilities (including developmental delay, cerebral palsy, visual impairment, autism and attention deficit disorder) was 33%. The main conditions associated with additional disabilities were syndromes and chromosomal abnormalities (87%), jaundice (86%), prematurity (62%), cytomegalovirus (60%), and inner ear abnormalities including cochlea nerve hypoplasia or aplasia (75%) and semicircular canal anomalies (56%). At 12 months postoperatively, almost all (96%) of the children without additional disabilities had a CAP score of 5 or greater (speech), compared with 52% of children with additional disabilities. Children with developmental delay had a median CAP score of 4, at 12 months compared with 6 for those without developmental delay. Additional disabilities are prevalent in approximately a third of pediatric cochlear implant patients. Additional disabilities significantly affect the outcomes of cochlear implants.

  1. Study of shallow junction formation by boron-containing cluster ion implantation of silicon and two-stage annealing

    NASA Astrophysics Data System (ADS)

    Lu, Xin-Ming

    Shallow junction formation made by low energy ion implantation and rapid thermal annealing is facing a major challenge for ULSI (ultra large scale integration) as the line width decreases down to the sub micrometer region. The issues include low beam current, the channeling effect in low energy ion implantation and TED (transient enhanced diffusion) during annealing after ion implantation. In this work, boron containing small cluster ions, such as GeB, SiB and SiB2, was generated by using the SNICS (source of negative ion by cesium sputtering) ion source to implant into Si substrates to form shallow junctions. The use of boron containing cluster ions effectively reduces the boron energy while keeping the energy of the cluster ion beam at a high level. At the same time, it reduces the channeling effect due to amorphization by co-implanted heavy atoms like Ge and Si. Cluster ions have been used to produce 0.65--2keV boron for low energy ion implantation. Two stage annealing, which is a combination of low temperature (550°C) preannealing and high temperature annealing (1000°C), was carried out to anneal the Si sample implanted by GeB, SiBn clusters. The key concept of two-step annealing, that is, the separation of crystal regrowth, point defects removal with dopant activation from dopant diffusion, is discussed in detail. The advantages of the two stage annealing include better lattice structure, better dopant activation and retarded boron diffusion. The junction depth of the two stage annealed GeB sample was only half that of the one-step annealed sample, indicating that TED was suppressed by two stage annealing. Junction depths as small as 30 nm have been achieved by two stage annealing of sample implanted with 5 x 10-4/cm2 of 5 keV GeB at 1000°C for 1 second. The samples were evaluated by SIMS (secondary ion mass spectrometry) profiling, TEM (transmission electron microscopy) and RBS (Rutherford Backscattering Spectrometry)/channeling. Cluster ion implantation

  2. Auditory Implant Research at the House Ear Institute 1989–2013

    PubMed Central

    Shannon, Robert V.

    2014-01-01

    The House Ear Institute (HEI) had a long and distinguished history of auditory implant innovation and development. Early clinical innovations include being one of the first cochlear implant (CI) centers, being the first center to implant a child with a cochlear implant in the US, developing the auditory brainstem implant, and developing multiple surgical approaches and tools for Otology. This paper reviews the second stage of auditory implant research at House – in-depth basic research on perceptual capabilities and signal processing for both cochlear implants and auditory brainstem implants. Psychophysical studies characterized the loudness and temporal perceptual properties of electrical stimulation as a function of electrical parameters. Speech studies with the noise-band vocoder showed that only four bands of tonotopically arrayed information were sufficient for speech recognition, and that most implant users were receiving the equivalent of 8–10 bands of information. The noise-band vocoder allowed us to evaluate the effects of the manipulation of the number of bands, the alignment of the bands with the original tonotopic map, and distortions in the tonotopic mapping, including holes in the neural representation. Stimulation pulse rate was shown to have only a small effect on speech recognition. Electric fields were manipulated in position and sharpness, showing the potential benefit of improved tonotopic selectivity. Auditory training shows great promise for improving speech recognition for all patients. And the Auditory Brainstem Implant was developed and improved and its application expanded to new populations. Overall, the last 25 years of research at HEI helped increase the basic scientific understanding of electrical stimulation of hearing and contributed to the improved outcomes for patients with the CI and ABI devices. PMID:25449009

  3. Energy efficient low-noise neural recording amplifier with enhanced noise efficiency factor.

    PubMed

    Majidzadeh, V; Schmid, A; Leblebici, Y

    2011-06-01

    This paper presents a neural recording amplifier array suitable for large-scale integration with multielectrode arrays in very low-power microelectronic cortical implants. The proposed amplifier is one of the most energy-efficient structures reported to date, which theoretically achieves an effective noise efficiency factor (NEF) smaller than the limit that can be achieved by any existing amplifier topology, which utilizes a differential pair input stage. The proposed architecture, which is referred to as a partial operational transconductance amplifier sharing architecture, results in a significant reduction of power dissipation as well as silicon area, in addition to the very low NEF. The effect of mismatch on crosstalk between channels and the tradeoff between noise and crosstalk are theoretically analyzed. Moreover, a mathematical model of the nonlinearity of the amplifier is derived, and its accuracy is confirmed by simulations and measurements. For an array of four neural amplifiers, measurement results show a midband gain of 39.4 dB and a -3-dB bandwidth ranging from 10 Hz to 7.2 kHz. The input-referred noise integrated from 10 Hz to 100 kHz is measured at 3.5 μVrms and the power consumption is 7.92 μW from a 1.8-V supply, which corresponds to NEF = 3.35. The worst-case crosstalk and common-mode rejection ratio within the desired bandwidth are - 43.5 dB and 70.1 dB, respectively, and the active silicon area of each amplifier is 256 μm × 256 μm in 0.18-μm complementary metal-oxide semiconductor technology.

  4. Next generation brain implant coatings and nerve regeneration via novel conductive nanocomposite development.

    PubMed

    Antoniadou, Eleni V; Ahmad, Rezal K; Jackman, Richard B; Seifalian, Alexander M

    2011-01-01

    Composite materials based on the coupling of conductive organic polymers and carbon nanotubes have shown that they possess properties of the individual components with a synergistic effect. Multi-wall carbon nanotube (MWCNT)/ polymer composites are hybrid materials that combine numerous mechanical, electrical and chemical properties and thus, constitute ideal biomaterials for a wide range of regenerative medicine applications. Although, complete dispersion of CNT in a polymer matrix has rarely been achieved, in this study we have succeeded high dispersibility of CNT in POSS-PCU and POSS-PCL, novel polymers based on polyprolactone and polycarbonate polyurethane (PCU) and poly(caprolactoneurea)urethane both having incorporated polyhedral oligomeric silsesquioxane (POSS). We report the synthesis and characterization of a novel biomaterial that possesses unique properties of being electrically conducting and thus being capable of electronic interfacing with tissue. To this end, POSS-PCU/MWCNT composite can be used as a biomaterial for the development of nerve guidance channels to promote nerve regeneration and POSS-PCL/MWCNT as a substrate to increase electronic interfacing between neurons and micro-machined electrodes for potential applications in neural probes, prosthetic devices and brain implants.

  5. Personal reflections on the multichannel cochlear implant and a view of the future.

    PubMed

    Clark, Graeme M

    2008-01-01

    The multichannel cochlear implant is the first neural prosthesis to effectively and safely bring electronic technology into a direct physiological relation with the central nervous system and human consciousness. It is also the first cochlear implant to give speech understanding to tens of thousands of persons with profound deafness and spoken language to children born deaf in more than 80 countries. In so doing, it is the first major advance in research and technology to help deaf children communicate since Sign Language of the Deaf was developed at the Paris deaf school (L'Institut National de Jeunes Sourds de Paris) >200 years ago. Furthermore, biomedical research has been fundamental for ensuring that the multielectrode implant is safe as well as effective. More recent research has also shown that bilateral implants confer the benefits of binaural hearing. Future research using nanotechnology should see high-fidelity sound received, which would help deaf persons communicate in noise and enjoy music. Research should also lead to implants in ears with useful hearing.

  6. Surface smoothing and template partitioning for cranial implant CAD

    NASA Astrophysics Data System (ADS)

    Min, Kyoung-june; Dean, David

    2005-04-01

    Employing patient-specific prefabricated implants can be an effective treatment for large cranial defects (i.e., > 25 cm2). We have previously demonstrated the use of Computer Aided Design (CAD) software that starts with the patient"s 3D head CT-scan. A template is accurately matched to the pre-detected skull defect margin. For unilateral cranial defects the template is derived from a left-to-right mirrored skull image. However, two problems arise: (1) slice edge artifacts generated during isosurface polygonalization are inherited by the final implant; and (2) partitioning (i.e., cookie-cutting) the implant surface from the mirrored skull image usually results in curvature discontinuities across the interface between the patient"s defect and the implant. To solve these problems, we introduce a novel space curve-to-surface partitioning algorithm following a ray-casting surface re-sampling and smoothing procedure. Specifically, the ray-cast re-sampling is followed by bilinear interpolation and low-pass filtering. The resulting surface has a highly regular grid-like topological structure of quadrilaterally arranged triangles. Then, we replace the regions to be partitioned with predefined sets of triangular elements thereby cutting the template surface to accurately fit the defect margin at high resolution and without surface curvature discontinuities. Comparisons of the CAD implants for five patients against the manually generated implant that the patient actually received show an average implant-patient gap of 0.45mm for the former and 2.96mm for the latter. Also, average maximum normalized curvature of interfacing surfaces was found to be smoother, 0.043, for the former than the latter, 0.097. This indicates that the CAD implants would provide a significantly better fit.

  7. Time Multiplexed Active Neural Probe with 1356 Parallel Recording Sites

    PubMed Central

    Raducanu, Bogdan C.; Yazicioglu, Refet F.; Lopez, Carolina M.; Putzeys, Jan; Andrei, Alexandru; Rochus, Veronique; Welkenhuysen, Marleen; van Helleputte, Nick; Musa, Silke; Puers, Robert; Kloosterman, Fabian; Van Hoof, Chris; Mitra, Srinjoy

    2017-01-01

    We present a high electrode density and high channel count CMOS (complementary metal-oxide-semiconductor) active neural probe containing 1344 neuron sized recording pixels (20 µm × 20 µm) and 12 reference pixels (20 µm × 80 µm), densely packed on a 50 µm thick, 100 µm wide, and 8 mm long shank. The active electrodes or pixels consist of dedicated in-situ circuits for signal source amplification, which are directly located under each electrode. The probe supports the simultaneous recording of all 1356 electrodes with sufficient signal to noise ratio for typical neuroscience applications. For enhanced performance, further noise reduction can be achieved while using half of the electrodes (678). Both of these numbers considerably surpass the state-of-the art active neural probes in both electrode count and number of recording channels. The measured input referred noise in the action potential band is 12.4 µVrms, while using 678 electrodes, with just 3 µW power dissipation per pixel and 45 µW per read-out channel (including data transmission). PMID:29048396

  8. Attachment systems for mandibular implant overdentures: a systematic review

    PubMed Central

    Kim, Ha-Young; Lee, Jeong-Yol; Bryant, S. Ross

    2012-01-01

    PURPOSE The aim of this systematic review was to address treatment outcome according to attachment systems for mandibular implant overdentures in terms of implant survival rate, prosthetic maintenance and complications, and patient satisfaction. MATERIALS AND METHODS A systematic literature search was conducted using PubMed and hand searching of relevant journals considering inclusion and exclusion criteria. Clinical trial studies on mandibular implant overdentures until August, 2010 were selected if more than one type of overdenture attachment was reported. Twenty four studies from 1098 studies were finally included and the data on implant survival rate, prosthetic maintenance and complications, patient satisfaction were analyzed relative to attachment systems. RESULTS Four studies presented implant survival rates (95.8 - 97.5% for bar, 96.2 - 100% for ball, 91.7% for magnet) according to attachment system. Ten other studies presented an implant survival rate ranging from 93.3% to 100% without respect to the attachment groups. Common prosthetic maintenance and complications were replacement of an assay for magnet attachments, and activation of a matrix or clip for ball or bar attachments. Prosthetic maintenance and complications most commonly occurred in the magnet groups. Conflicting findings were found on the rate of prosthetic maintenance and complications comparing ball and bar attachments. Most studies showed no significant differences in patient satisfaction depending upon attachment systems. CONCLUSION The implant survival rate of mandibular overdentures seemed to be high regardless attachment systems. The prosthetic maintenance and complications may be influenced by attachment systems. However patient satisfaction may be independent of the attachment system. PMID:23236571

  9. Clinical and Radiological Long-Term Outcome of a Tapered Implant System with Special Emphasis on the Influence of Augmentation Procedures.

    PubMed

    Schiegnitz, Eik; Al-Nawas, Bilal; Tegner, Alexander; Sagheb, Keyvan; Berres, Manfred; Kämmerer, Peer W; Wagner, Wilfried

    2016-08-01

    Tapered implant designs aim to improve primary stability and implant survival in soft bone. However, respective clinical long-term data are scarce. Therefore, a clinical and radiological evaluation of the long-term success of a transgingival-supracrestal inserted tapered implant system with special emphasis on the influence of augmentation procedures was conducted. In a retrospective study design, all in the Department of Oral and Maxillofacial Surgery of the University Medical Centre, Mainz, Germany, between May 2002 and March 2012, placed tapered implants (Straumann TE®, Basel, Switzerland) were analyzed. In this time period, a total of one hundred ninety-seven tapered implants were inserted in 90 patients. For patients available for clinical recall, success criteria according to Albrektsson and Buser were evaluated. The in situ rate was 96.3% after an average time in situ of 62 ± 31 months. In one hundred twenty-seven sites, bone augmentation procedures were performed. Hereof, 96 sites were sinus augmentation procedures and 31 sites were alveolar ridge augmentations. For patients with sinus augmentation procedures, implant survival was 97.9% and for patients with alveolar ridge augmentations, implant survival was 93.5% after 5 years, indicating a higher implant survival for sinus augmentation, however not statistically different (p = .194). Implant diameter and timing of implant placement had no significant impact on implant survival (p > .05). Mean marginal bone loss was -0.50 ± 1.54 mm for patients receiving maxillary sinus augmentation and -1.16 ± 1.13 mm for patients with alveolar ridge augmentations, indicating a lower marginal bone loss in patients receiving maxillary sinus augmentation (p = .046). Implant success rates ranged between 88% and 92% after a mean follow-up of 6 years. Within the limits of the retrospective character of this study, the tapered soft tissue level implant showed especially in maxillary sinus

  10. Low-cost carbon thick-film strain sensors for implantable applications

    NASA Astrophysics Data System (ADS)

    Gutierrez, Christian A.; Meng, Ellis

    2010-09-01

    The suitability of low-cost carbon thick-film strain sensors embedded within a biomedical grade silicone rubber (Silastic® MDX4-4210) for implantable applications is investigated. These sensors address the need for robust cost-effective implantable strain sensing technology for the closed loop operation of function-restoring neural prosthetic systems. Design, fabrication and characterization of the sensors are discussed in the context of the application to strain/fullness measurements of the urinary bladder as part of the neuroprosthetic treatment of lower urinary tract dysfunction. The fabrication process, utilizing off-the-shelf screen-printing materials, is convenient and cost effective while achieving resolutions down to 75 µm. This method can also be extended to produce multilayer embedded devices by superposition of different screen-printable materials. Uniaxial loading performance, temperature dependence and long-term soak testing are used to validate suitability for implantation while proof-of-concept operation (up to 40% strain) is demonstrated on a bench-top latex balloon bladder model.

  11. Tetherless near-infrared control of brain activity in behaving animals using fully implantable upconversion microdevices.

    PubMed

    Wang, Ying; Lin, Xudong; Chen, Xi; Chen, Xian; Xu, Zhen; Zhang, Wenchong; Liao, Qinghai; Duan, Xin; Wang, Xin; Liu, Ming; Wang, Feng; He, Jufang; Shi, Peng

    2017-10-01

    Many nanomaterials can be used as sensors or transducers in biomedical research and they form the essential components of transformative novel biotechnologies. In this study, we present an all-optical method for tetherless remote control of neural activity using fully implantable micro-devices based on upconversion technology. Upconversion nanoparticles (UCNPs) were used as transducers to convert near-infrared (NIR) energy to visible light in order to stimulate neurons expressing different opsin proteins. In our setup, UCNPs were packaged in a glass micro-optrode to form an implantable device with superb long-term biocompatibility. We showed that remotely applied NIR illumination is able to reliably trigger spiking activity in rat brains. In combination with a robotic laser projection system, the upconversion-based tetherless neural stimulation technique was implemented to modulate brain activity in various regions, including the striatum, ventral tegmental area, and visual cortex. Using this system, we were able to achieve behavioral conditioning in freely moving animals. Notably, our microscale device was at least one order of magnitude smaller in size (∼100 μm in diameter) and two orders of magnitude lighter in weight (less than 1 mg) than existing wireless optogenetic devices based on light-emitting diodes. This feature allows simultaneous implantation of multiple UCNP-optrodes to achieve modulation of brain function to control complex animal behavior. We believe that this technology not only represents a novel practical application of upconversion nanomaterials, but also opens up new possibilities for remote control of neural activity in the brains of behaving animals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. The perception of complex pitch in cochlear implants: A comparison of monopolar and tripolar stimulation.

    PubMed

    Fielden, Claire A; Kluk, Karolina; Boyle, Patrick J; McKay, Colette M

    2015-10-01

    Cochlear implant listeners typically perform poorly in tasks of complex pitch perception (e.g., musical pitch and voice pitch). One explanation is that wide current spread during implant activation creates channel interactions that may interfere with perception of temporal fundamental frequency information contained in the amplitude modulations within channels. Current focusing using a tripolar mode of stimulation has been proposed as a way of reducing channel interactions, minimising spread of excitation and potentially improving place and temporal pitch cues. The present study evaluated the effect of mode in a group of cochlear implant listeners on a pitch ranking task using male and female singing voices separated by either a half or a quarter octave. Results were variable across participants, but on average, pitch ranking was at chance level when the pitches were a quarter octave apart and improved when the difference was a half octave. No advantage was observed for tripolar over monopolar mode at either pitch interval, suggesting that previously published psychophysical advantages for focused modes may not translate into improvements in complex pitch ranking. Evaluation of the spectral centroid of the stimulation pattern, plus a lack of significant difference between male and female voices, suggested that participants may have had difficulty in accessing temporal pitch cues in either mode.

  13. Aberrant modulation of a delayed rectifier potassium channel by glutamate in Alzheimer's disease.

    PubMed

    Poulopoulou, Cornelia; Markakis, Ioannis; Davaki, Panagiota; Tsaltas, Eleftheria; Rombos, Antonis; Hatzimanolis, Alexandros; Vassilopoulos, Dimitrios

    2010-02-01

    In Alzheimer's disease (AD), potassium channel abnormalities have been reported in both neural and peripheral tissues. Herein, using whole-cell patch-clamp, we demonstrate an aberrant glutamate-dependent modulation of K(V)1.3 channels in T lymphocytes of AD patients. Although intrinsic K(V)1.3 properties in patients were similar to healthy individuals, glutamate (1-1000 microM) failed to yield the hyperpolarizing shift normally observed in K(V)1.3 steady-state inactivation (-4.4+/-2.7 mV in AD vs. -14.3+/-2.5 mV in controls, 10 microM glutamate), resulting in a 4-fold increase of resting channel activity. Specific agonist and antagonist data indicate that this abnormality is due to dysfunction of cognate group II mGluRs. Given that glutamate is present in plasma and that both mGluRs and K(V)1.3 channels regulate T-lymphocyte responsiveness, our finding may account for the presence of immune-associated alterations in AD. Furthermore, if this aberration reflects a corresponding one in neural tissue, it could provide a potential target in AD pathogenesis.

  14. Charge states and lattice sites of dilute implanted Sn in ZnO

    NASA Astrophysics Data System (ADS)

    Mølholt, T. E.; Gunnlaugsson, H. P.; Johnston, K.; Mantovan, R.; Röder, J.; Adoons, V.; Mokhles Gerami, A.; Masenda, H.; Matveyev, Y. A.; Ncube, M.; Unzueta, I.; Bharuth-Ram, K.; Gislason, H. P.; Krastev, P.; Langouche, G.; Naidoo, D.; Ólafsson, S.; Zenkevich, A.; ISOLDE Collaboration

    2017-04-01

    The common charge states of Sn are 2+  and 4+. While charge neutrality considerations favour 2+  to be the natural charge state of Sn in ZnO, there are several reports suggesting the 4+  state instead. In order to investigate the charge states, lattice sites, and the effect of the ion implantation process of dilute Sn atoms in ZnO, we have performed 119Sn emission Mössbauer spectroscopy on ZnO single crystal samples following ion implantation of radioactive 119In (T ½  =  2.4 min) at temperatures between 96 K and 762 K. Complementary perturbed angular correlation measurements on 111mCd implanted ZnO were also conducted. Our results show that the 2+  state is the natural charge state for Sn in defect free ZnO and that the 4+  charge state is stabilized by acceptor defects created in the implantation process.

  15. Ion implantation of indium gallium arsenide

    NASA Astrophysics Data System (ADS)

    Almonte, Marlene Isabel

    The ternary compound In0.53Ga0.47As, lattice-matched to Inp, is a semiconductor alloy of technological importance for numerous electronic and optoelectronic device applications. One of these applications includes photodiodes to be developed for the 1.3--1.55 mum wavelength range where silica fibers have their lowest optical loss. With a rapid increase in its use there is an essential need to understand the effects of ion implantation of this alloy semiconductor for implant isolation purposes in which highly resistive layers are required. Due to the small band gap (0.75 eV at 300K) of In0.53Ga0.47As, the estimated maximum resistivity is of the order of 1000 O-cm. Implant isolation can be achieved by the implantation of either inert noble gas ions or electrically active ions. Ion bombardment with inert species introduces defects which trap charge carriers. In the case of implant isolation by electrically active ions, the implanted impurities form an electronic level located close to the middle of the bandgap. Studies of the effects of implantation in In0.53Ga0.47 As due to damage by implantation of Ne+ ions and to compensation by implantation of Fe+ ions are reported in this thesis. The former only involves lattice damage related effects while the latter leads to damage and dopant induced compensation. From the Ne+ implantation results it appears that the damage related energy levels in In0.53 Ga0.47M produced by ion bombardment of chemically inactive species, are not sufficiently deep to lead to effective isolation. A higher resistivity of the order of 770 O-cm is achieved with Fe+ implantation, indicating that Fe introduces an energy level deep in the bandgap. The changes in the electrical properties of the layers are correlated to the lattice damage (damage induced effects) and/or the diffusion of the compensating dopants (dopant induced compensation). Structural characterization of the layers is performed with channeling Rutherford Backscattering Spectrometry

  16. Electrophoretic deposition of ligand-free platinum nanoparticles on neural electrodes affects their impedance in vitro and in vivo with no negative effect on reactive gliosis.

    PubMed

    Angelov, Svilen D; Koenen, Sven; Jakobi, Jurij; Heissler, Hans E; Alam, Mesbah; Schwabe, Kerstin; Barcikowski, Stephan; Krauss, Joachim K

    2016-01-12

    Electrodes for neural stimulation and recording are used for the treatment of neurological disorders. Their features critically depend on impedance and interaction with brain tissue. The effect of surface modification on electrode impedance was examined in vitro and in vivo after intracranial implantation in rats. Electrodes coated by electrophoretic deposition with platinum nanoparticles (NP; <10 and 50 nm) as well as uncoated references were implanted into the rat's subthalamic nucleus. After postoperative recovery, rats were electrostimulated for 3 weeks. Impedance was measured before implantation, after recovery and then weekly during stimulation. Finally, local field potential was recorded and tissue-to-implant reaction was immunohistochemically studied. Coating with NP significantly increased electrode's impedance in vitro. Postoperatively, the impedance of all electrodes was temporarily further increased. This effect was lowest for the electrodes coated with particles <10 nm, which also showed the most stable impedance dynamics during stimulation for 3 weeks and the lowest total power of local field potential during neuronal activity recording. Histological analysis revealed that NP-coating did not affect glial reactions or neural cell-count. Coating with NP <10 nm may improve electrode's impedance stability without affecting biocompatibility. Increased impedance after NP-coating may improve neural recording due to better signal-to-noise ratio.

  17. Speaker normalization for chinese vowel recognition in cochlear implants.

    PubMed

    Luo, Xin; Fu, Qian-Jie

    2005-07-01

    Because of the limited spectra-temporal resolution associated with cochlear implants, implant patients often have greater difficulty with multitalker speech recognition. The present study investigated whether multitalker speech recognition can be improved by applying speaker normalization techniques to cochlear implant speech processing. Multitalker Chinese vowel recognition was tested with normal-hearing Chinese-speaking subjects listening to a 4-channel cochlear implant simulation, with and without speaker normalization. For each subject, speaker normalization was referenced to the speaker that produced the best recognition performance under conditions without speaker normalization. To match the remaining speakers to this "optimal" output pattern, the overall frequency range of the analysis filter bank was adjusted for each speaker according to the ratio of the mean third formant frequency values between the specific speaker and the reference speaker. Results showed that speaker normalization provided a small but significant improvement in subjects' overall recognition performance. After speaker normalization, subjects' patterns of recognition performance across speakers changed, demonstrating the potential for speaker-dependent effects with the proposed normalization technique.

  18. Risk factors for implant failure: a retrospective study in an educational institution using GEE analyses.

    PubMed

    Borba, Marcelo; Deluiz, Daniel; Lourenço, Eduardo José Veras; Oliveira, Luciano; Tannure, Patrícia Nivoloni

    2017-08-21

    This study aimed to evaluate dental implant outcomes and to identify risk factors associated with implant failure over 12 years via dental records of patients attending an educational institution. Dental records of 202 patients receiving 774 dental implants from 2002 to 2014 were analyzed by adopting a more reliable statistical method to evaluate risk factors with patients as the unit [generalized estimating equation (GEE)]. Information regarding patient age at implantation, sex, use of tobacco, and history of systemic diseases was collected. Information about implant location in the arch region and implant length, diameter, and placement in a grafted area was evaluated after 2 years under load. Systemic and local risk factors for early and late implant failure were studied. A total of 18 patients experienced 25 implant failures, resulting in an overall survival rate of 96.8% (2.84% and 0.38% early and late implant failures, respectively). The patient-based survival rate was 91.8%. GEE univariate and multivariate analyses revealed that a significant risk factor for implant failure was the maxillary implant (p = 0.006 and p = 0.014, respectively). Bone grafting appeared to be a risk factor for implant failure (p = 0.054). According to GEE analyses, maxillary implants had significantly worse outcomes in this population and were considered to be a risk factor for implant failure. Our results suggested that implants placed in a bone augmentation area had a tendency to fail.

  19. Identification of musical instruments by normal-hearing subjects listening through a cochlear-implant simulation

    NASA Astrophysics Data System (ADS)

    Reich, Rebecca D.; Eddington, Donald

    2002-05-01

    Signal processing in a cochlear implant (CI) is primarily designed to convey speech and environmental sounds, and can cause distortion of musical timbre. Systematic investigation of musical instrument identification through a CI has not yet revealed how timbre is affected by the implant's processing. In this experiment, the bandpass filtering, rectification, and low-pass filtering of an implant are simulated in MATLAB. Synthesized signals representing 12 common instruments, each performing a major scale, are processed by simulations using up to 8 analysis channels. The unprocessed recordings, together with the 8 simulation conditions for 12 instruments, are presented in random order to each of the subjects. The subject's task is to identify the instrument represented by each item. The subjects also subjectively score each item based on similarity and pleasantness. We anticipate performance using the simulation will be worse than the unprocessed condition because of the limited information delivered by the envelopes of the analysis channels. These results will be analyzed as a confusion matrix and provide a basis for contrasting the information used by subjects listening to the unprocessed and processed materials. Understanding these differences should aid in the development of new processing strategies to better represent music for cochlear implant users.

  20. Disorder generated by interacting neural networks: application to econophysics and cryptography

    NASA Astrophysics Data System (ADS)

    Kinzel, Wolfgang; Kanter, Ido

    2003-10-01

    When neural networks are trained on their own output signals they generate disordered time series. In particular, when two neural networks are trained on their mutual output they can synchronize; they relax to a time-dependent state with identical synaptic weights. Two applications of this phenomenon are discussed for (a) econophysics and (b) cryptography. (a) When agents competing in a closed market (minority game) are using neural networks to make their decisions, the total system relaxes to a state of good performance. (b) Two partners communicating over a public channel can find a common secret key.