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Sample records for cortical laminar-electrode recordings

  1. Estimation of Thalamocortical and Intracortical Network Models from Joint Thalamic Single-Electrode and Cortical Laminar-Electrode Recordings in the Rat Barrel System

    PubMed Central

    Blomquist, Patrick; Devor, Anna; Indahl, Ulf G.; Ulbert, Istvan; Einevoll, Gaute T.; Dale, Anders M.

    2009-01-01

    A new method is presented for extraction of population firing-rate models for both thalamocortical and intracortical signal transfer based on stimulus-evoked data from simultaneous thalamic single-electrode and cortical recordings using linear (laminar) multielectrodes in the rat barrel system. Time-dependent population firing rates for granular (layer 4), supragranular (layer 2/3), and infragranular (layer 5) populations in a barrel column and the thalamic population in the homologous barreloid are extracted from the high-frequency portion (multi-unit activity; MUA) of the recorded extracellular signals. These extracted firing rates are in turn used to identify population firing-rate models formulated as integral equations with exponentially decaying coupling kernels, allowing for straightforward transformation to the more common firing-rate formulation in terms of differential equations. Optimal model structures and model parameters are identified by minimizing the deviation between model firing rates and the experimentally extracted population firing rates. For the thalamocortical transfer, the experimental data favor a model with fast feedforward excitation from thalamus to the layer-4 laminar population combined with a slower inhibitory process due to feedforward and/or recurrent connections and mixed linear-parabolic activation functions. The extracted firing rates of the various cortical laminar populations are found to exhibit strong temporal correlations for the present experimental paradigm, and simple feedforward population firing-rate models combined with linear or mixed linear-parabolic activation function are found to provide excellent fits to the data. The identified thalamocortical and intracortical network models are thus found to be qualitatively very different. While the thalamocortical circuit is optimally stimulated by rapid changes in the thalamic firing rate, the intracortical circuits are low-pass and respond most strongly to slowly varying

  2. Modeling vocalization with ECoG cortical activity recorded during vocal production in the macaque monkey.

    PubMed

    Fukushima, Makoto; Saunders, Richard C; Fujii, Naotaka; Averbeck, Bruno B; Mishkin, Mortimer

    2014-01-01

    Vocal production is an example of controlled motor behavior with high temporal precision. Previous studies have decoded auditory evoked cortical activity while monkeys listened to vocalization sounds. On the other hand, there have been few attempts at decoding motor cortical activity during vocal production. Here we recorded cortical activity during vocal production in the macaque with a chronically implanted electrocorticographic (ECoG) electrode array. The array detected robust activity in motor cortex during vocal production. We used a nonlinear dynamical model of the vocal organ to reduce the dimensionality of `Coo' calls produced by the monkey. We then used linear regression to evaluate the information in motor cortical activity for this reduced representation of calls. This simple linear model accounted for circa 65% of the variance in the reduced sound representations, supporting the feasibility of using the dynamical model of the vocal organ for decoding motor cortical activity during vocal production. PMID:25571556

  3. Cortical gamma oscillations modulated by word association tasks: intracranial recording.

    PubMed

    Thampratankul, Lunliya; Nagasawa, Tetsuro; Rothermel, Robert; Juhasz, Csaba; Sood, Sandeep; Asano, Eishi

    2010-05-01

    Recent studies have suggested that cortical activation can be measured using event-related augmentation of gamma oscillations in humans. We determined how commonly and differentially gamma oscillations (50-150Hz) were modulated by three distinct word-association tasks during extraoperative electrocorticography monitoring in a patient with focal epilepsy who underwent epilepsy surgery. He was auditorily presented names of common foods (e.g., apple) during each task. He was instructed to overtly verbalize the color (e.g., red) of each given food during the first association task, the taste (e.g., sweet) during the second task, and the texture (e.g., crunchy) during the third task. All three word-association tasks commonly elicited significant augmentation of gamma oscillations in the superior temporal gyrus, the middle temporal gyrus, and the inferior frontal gyrus, as well as the pre- and postcentral gyri. The food-texture association task specifically elicited significant gamma augmentation in the supramarginal gyrus. This preliminary study generated the hypothesis that word-association tasks may supplement functional language mapping using electrical stimulation. Differential gamma augmentation in the supramarginal gyrus might be attributed to a larger workload required in the food-texture association task compared with the remaining two tasks. PMID:20451464

  4. Hemodynamic and Electrophysiological Connectivity in the Language System: Simultaneous Near-Infrared Spectroscopy and Electrocorticography Recordings during Cortical Stimulation

    ERIC Educational Resources Information Center

    Sato, Yosuke; Oishi, Makoto; Fukuda, Masafumi; Fujii, Yukihiko

    2012-01-01

    We applied near-infrared spectroscopy (NIRS) and electrocorticography (ECoG) recordings during cortical stimulation to a temporal lobe epilepsy patient who underwent subdural electrode implantation. Using NIRS, changes in blood concentrations of oxyhemoglobin (HbO[subscript 2]) and deoxyhemoglobin (HbR) during cortical stimulation of the left…

  5. Robust Off- and Online Separation of Intracellularly Recorded Up and Down Cortical States

    PubMed Central

    Seamari, Yamina; Narváez, José A.; Vico, Francisco J.; Lobo, Daniel; Sanchez-Vives, Maria V.

    2007-01-01

    Background The neuronal cortical network generates slow (<1 Hz) spontaneous rhythmic activity that emerges from the recurrent connectivity. This activity occurs during slow wave sleep or anesthesia and also in cortical slices, consisting of alternating up (active, depolarized) and down (silent, hyperpolarized) states. The search for the underlying mechanisms and the possibility of analyzing network dynamics in vitro has been subject of numerous studies. This exposes the need for a detailed quantitative analysis of the membrane fluctuating behavior and computerized tools to automatically characterize the occurrence of up and down states. Methodology/Principal Findings Intracellular recordings from different areas of the cerebral cortex were obtained from both in vitro and in vivo preparations during slow oscillations. A method that separates up and down states recorded intracellularly is defined and analyzed here. The method exploits the crossover of moving averages, such that transitions between up and down membrane regimes can be anticipated based on recent and past voltage dynamics. We demonstrate experimentally the utility and performance of this method both offline and online, the online use allowing to trigger stimulation or other events in the desired period of the rhythm. This technique is compared with a histogram-based approach that separates the states by establishing one or two discriminating membrane potential levels. The robustness of the method presented here is tested on data that departs from highly regular alternating up and down states. Conclusions/Significance We define a simple method to detect cortical states that can be applied in real time for offline processing of large amounts of recorded data on conventional computers. Also, the online detection of up and down states will facilitate the study of cortical dynamics. An open-source MATLAB® toolbox, and Spike 2®-compatible version are made freely available. PMID:17849017

  6. Decoding spoken words using local field potentials recorded from the cortical surface

    NASA Astrophysics Data System (ADS)

    Kellis, Spencer; Miller, Kai; Thomson, Kyle; Brown, Richard; House, Paul; Greger, Bradley

    2010-10-01

    Pathological conditions such as amyotrophic lateral sclerosis or damage to the brainstem can leave patients severely paralyzed but fully aware, in a condition known as 'locked-in syndrome'. Communication in this state is often reduced to selecting individual letters or words by arduous residual movements. More intuitive and rapid communication may be restored by directly interfacing with language areas of the cerebral cortex. We used a grid of closely spaced, nonpenetrating micro-electrodes to record local field potentials (LFPs) from the surface of face motor cortex and Wernicke's area. From these LFPs we were successful in classifying a small set of words on a trial-by-trial basis at levels well above chance. We found that the pattern of electrodes with the highest accuracy changed for each word, which supports the idea that closely spaced micro-electrodes are capable of capturing neural signals from independent neural processing assemblies. These results further support using cortical surface potentials (electrocorticography) in brain-computer interfaces. These results also show that LFPs recorded from the cortical surface (micro-electrocorticography) of language areas can be used to classify speech-related cortical rhythms and potentially restore communication to locked-in patients.

  7. Chronic cortical and electromyographic recordings from a fully implantable device: preclinical experience in a nonhuman primate

    NASA Astrophysics Data System (ADS)

    Ryapolova-Webb, Elena; Afshar, Pedram; Stanslaski, Scott; Denison, Tim; de Hemptinne, Coralie; Bankiewicz, Krystof; Starr, Philip A.

    2014-02-01

    Objective. Analysis of intra- and perioperatively recorded cortical and basal ganglia local field potentials in human movement disorders has provided great insight into the pathophysiology of diseases such as Parkinson's, dystonia, and essential tremor. However, in order to better understand the network abnormalities and effects of chronic therapeutic stimulation in these disorders, long-term recording from a fully implantable data collection system is needed. Approach. A fully implantable investigational data collection system, the Activa® PC + S neurostimulator (Medtronic, Inc., Minneapolis, MN), has been developed for human use. Here, we tested its utility for extended intracranial recording in the motor system of a nonhuman primate. The system was attached to two quadripolar paddle arrays: one covering sensorimotor cortex, and one covering a proximal forelimb muscle, to study simultaneous cortical field potentials and electromyography during spontaneous transitions from rest to movement. Main results. Over 24 months of recording, movement-related changes in physiologically relevant frequency bands were readily detected, including beta and gamma signals at approximately 2.5 μV/\\sqrtHz and 0.7 μV/\\sqrt{Hz}, respectively. The system architecture allowed for flexible recording configurations and algorithm triggered data recording. In the course of physiological analyses, sensing artifacts were observed (˜1 μVrms stationary tones at fixed frequency), which were mitigated either with post-processing or algorithm design and did not impact the scientific conclusions. Histological examination revealed no underlying tissue damage; however, a fibrous capsule had developed around the paddles, demonstrating a potential mechanism for the observed signal amplitude reduction. Significance. This study establishes the usefulness of this system in measuring chronic brain and muscle signals. Use of this system may potentially be valuable in human trials of chronic brain

  8. Noninvasive scalp recording of cortical auditory evoked potentials in the alert macaque monkey.

    PubMed

    Itoh, Kosuke; Nejime, Masafumi; Konoike, Naho; Nakada, Tsutomu; Nakamura, Katsuki

    2015-09-01

    Scalp-recorded evoked potentials (EP) provide researchers and clinicians with irreplaceable means for recording stimulus-related neural activities in the human brain, due to its high temporal resolution, handiness, and, perhaps more importantly, non-invasiveness. This work recorded the scalp cortical auditory EP (CAEP) in unanesthetized monkeys by using methods that are essentially identical to those applied to humans. Young adult rhesus monkeys (Macaca mulatta, 5-7 years old) were seated in a monkey chair, and their head movements were partially restricted by polystyrene blocks and tension poles placed around their head. Individual electrodes were fixated on their scalp using collodion according to the 10-20 system. Pure tone stimuli were presented while electroencephalograms were recorded from up to nineteen channels, including an electrooculogram channel. In all monkeys (n = 3), the recorded CAEP comprised a series of positive and negative deflections, labeled here as macaque P1 (mP1), macaque N1 (mN1), macaque P2 (mP2), and macaque N2 (mN2), and these transient responses to sound onset were followed by a sustained potential that continued for the duration of the sound, labeled the macaque sustained potential (mSP). mP1, mN2 and mSP were the prominent responses, and they had maximal amplitudes over frontal/central midline electrode sites, consistent with generators in auditory cortices. The study represents the first noninvasive scalp recording of CAEP in alert rhesus monkeys, to our knowledge. PMID:26031378

  9. Multi-electrode Array Recordings of Human Epileptic Postoperative Cortical Tissue

    PubMed Central

    Dossi, Elena; Blauwblomme, Thomas; Nabbout, Rima; Huberfeld, Gilles; Rouach, Nathalie

    2014-01-01

    Epilepsy, affecting about 1% of the population, comprises a group of neurological disorders characterized by the periodic occurrence of seizures, which disrupt normal brain function. Despite treatment with currently available antiepileptic drugs targeting neuronal functions, one third of patients with epilepsy are pharmacoresistant. In this condition, surgical resection of the brain area generating seizures remains the only alternative treatment. Studying human epileptic tissues has contributed to understand new epileptogenic mechanisms during the last 10 years. Indeed, these tissues generate spontaneous interictal epileptic discharges as well as pharmacologically-induced ictal events which can be recorded with classical electrophysiology techniques. Remarkably, multi-electrode arrays (MEAs), which are microfabricated devices embedding an array of spatially arranged microelectrodes, provide the unique opportunity to simultaneously stimulate and record field potentials, as well as action potentials of multiple neurons from different areas of the tissue. Thus MEAs recordings offer an excellent approach to study the spatio-temporal patterns of spontaneous interictal and evoked seizure-like events and the mechanisms underlying seizure onset and propagation. Here we describe how to prepare human cortical slices from surgically resected tissue and to record with MEAs interictal and ictal-like events ex vivo. PMID:25407747

  10. Optimization of microelectrode design for cortical recording based on thermal noise considerations.

    PubMed

    Lempka, Scott F; Johnson, Matthew D; Barnett, David W; Moffitt, Michael A; Otto, Kevin J; Kipke, Daryl R; McIntyre, Cameron C

    2006-01-01

    Intracortical microelectrode recordings of neural activity show great promise as control signals for neuroprosthetic applications. However, faithful, consistent recording of single unit spiking activity with chronically implanted silicon-substrate microelectrode arrays has proven difficult. Many approaches seek to enhance the long-term performance of microelectrode arrays by, for example, increasing electrode biocompatibility, decreasing electrode impedance, or improving electrode interface properties through application of small voltage pulses. The purpose of this study was to use computational models to optimize the design of microelectrodes. We coupled detailed models of the neural source signal, silicon-substrate microelectrodes, and thermal noise to define the electrode contact size that maximized the signal-to-noise ratio (SNR). Model analysis combined a multi-compartment cable model of a layer V cortical pyramidal neuron with a 3D finite element model of the head and microelectrode to define the amplitude and time course of the recorded signal. A spatially-lumped impedance model was parameterized with in vitro and in vivo spectroscopy data and used to define thermal noise as a function of electrode contact size. Our results suggest that intracortical microelectrodes with a contact size of ~380 microm2 will provide an increased SNR in vivo and improve the long-term recording capabilities of silicon-substrate microelectrode arrays. PMID:17947023

  11. Evaluation of the Neuroactivity of ToxCast Compounds Using Multi-well Microelectrode Array Recordings in Primary Cortical Neurons

    EPA Science Inventory

    Evaluation of the Neuroactivity of ToxCast Compounds Using Multi-well Microelectrode Array Recordings in Primary Cortical Neurons P Valdivia1, M Martin2, WR LeFew3, D Hall3, J Ross1, K Houck2 and TJ Shafer3 1Axion Biosystems, Atlanta GA and 2NCCT, 3ISTD, NHEERL, ORD, US EPA, RT...

  12. Cortical Source Analysis of High-Density EEG Recordings in Children

    PubMed Central

    Bathelt, Joe; O'Reilly, Helen; de Haan, Michelle

    2014-01-01

    EEG is traditionally described as a neuroimaging technique with high temporal and low spatial resolution. Recent advances in biophysical modelling and signal processing make it possible to exploit information from other imaging modalities like structural MRI that provide high spatial resolution to overcome this constraint1. This is especially useful for investigations that require high resolution in the temporal as well as spatial domain. In addition, due to the easy application and low cost of EEG recordings, EEG is often the method of choice when working with populations, such as young children, that do not tolerate functional MRI scans well. However, in order to investigate which neural substrates are involved, anatomical information from structural MRI is still needed. Most EEG analysis packages work with standard head models that are based on adult anatomy. The accuracy of these models when used for children is limited2, because the composition and spatial configuration of head tissues changes dramatically over development3.  In the present paper, we provide an overview of our recent work in utilizing head models based on individual structural MRI scans or age specific head models to reconstruct the cortical generators of high density EEG. This article describes how EEG recordings are acquired, processed, and analyzed with pediatric populations at the London Baby Lab, including laboratory setup, task design, EEG preprocessing, MRI processing, and EEG channel level and source analysis.  PMID:25045930

  13. Human occipital cortices differentially exert saccadic suppression: Intracranial recording in children.

    PubMed

    Uematsu, Mitsugu; Matsuzaki, Naoyuki; Brown, Erik C; Kojima, Katsuaki; Asano, Eishi

    2013-12-01

    By repeating saccades unconsciously, humans explore the surrounding world every day. Saccades inevitably move external visual images across the retina at high velocity; nonetheless, healthy humans don't perceive transient blurring of the visual scene during saccades. This perceptual stability is referred to as saccadic suppression. Functional suppression is believed to take place transiently in the visual systems, but it remains unknown how commonly or differentially the human occipital lobe activities are suppressed at the large-scale cortical network level. We determined the spatial-temporal dynamics of intracranially-recorded gamma activity at 80-150 Hz around spontaneous saccades under no-task conditions during wakefulness and those in darkness during REM sleep. Regardless of wakefulness or REM sleep, a small degree of attenuation of gamma activity was noted in the occipital regions during saccades, most extensively in the polar and least in the medial portions. Longer saccades were associated with more intense gamma-attenuation. Gamma-attenuation was subsequently followed by gamma-augmentation most extensively involving the medial and least involving the polar occipital region. Such gamma-augmentation was more intense during wakefulness and temporally locked to the offset of saccades. The polarities of initial peaks of perisaccadic event-related potentials (ERPs) were frequently positive in the medial and negative in the polar occipital regions. The present study, for the first time, provided the electrophysiological evidence that human occipital cortices differentially exert perisaccadic modulation. Transiently suppressed sensitivity of the primary visual cortex in the polar region may be an important neural basis for saccadic suppression. Presence of occipital gamma-attenuation even during REM sleep suggests that saccadic suppression might be exerted even without external visual inputs. The primary visual cortex in the medial region, compared to the polar

  14. Cortical Responses to Aδ-Fiber Stimulation: Magnetoencephalographic Recordings in a Subject Lacking Large Myelinated Afferents

    PubMed Central

    Olausson, Håkan; Cole, Jonathan; Jousmäki, Veikko; Hari, Riitta

    2010-01-01

    Controversy persists over the role of the primary somatosensory cortex (SI) in processing small-fiber peripheral afferent input. We therefore examined subject I.W, who, due to sensory neuronopathy syndrome, has no large-fiber afferents below C3 level. Cortical evoked responses were recorded with a whole-scalp neuromagnetometer to high-intensity electrical stimulation of the distal right radial, median, and tibial nerves and skin over the forearm and mechanical stimulation of (neurologically intact) lip. The responses to electrical stimulation in the Aβ-denervated limbs peaked at 110–140 ms in contralateral SI and at 140–220 ms in contralateral secondary somatosensory cortex (SII), consistent with Aδ-mediated input. I.W. was able to localize pin-prick stimuli with 4 cm accuracy. Responses to laser stimuli on the radial dorsum of the hand peaked in contralateral SII cortex at 215 ms, also compatible with Aδ-mediated input. These results support the role of the SI cortex in processing the sensory discriminative aspects of Aδ-mediated input. PMID:19959562

  15. Mismatch Responses in the Awake Rat: Evidence from Epidural Recordings of Auditory Cortical Fields

    PubMed Central

    Jung, Fabienne; Stephan, Klaas Enno; Backes, Heiko; Moran, Rosalyn; Gramer, Markus; Kumagai, Tetsuya; Graf, Rudolf

    2013-01-01

    Detecting sudden environmental changes is crucial for the survival of humans and animals. In the human auditory system the mismatch negativity (MMN), a component of auditory evoked potentials (AEPs), reflects the violation of predictable stimulus regularities, established by the previous auditory sequence. Given the considerable potentiality of the MMN for clinical applications, establishing valid animal models that allow for detailed investigation of its neurophysiological mechanisms is important. Rodent studies, so far almost exclusively under anesthesia, have not provided decisive evidence whether an MMN analogue exists in rats. This may be due to several factors, including the effect of anesthesia. We therefore used epidural recordings in awake black hooded rats, from two auditory cortical areas in both hemispheres, and with bandpass filtered noise stimuli that were optimized in frequency and duration for eliciting MMN in rats. Using a classical oddball paradigm with frequency deviants, we detected mismatch responses at all four electrodes in primary and secondary auditory cortex, with morphological and functional properties similar to those known in humans, i.e., large amplitude biphasic differences that increased in amplitude with decreasing deviant probability. These mismatch responses significantly diminished in a control condition that removed the predictive context while controlling for presentation rate of the deviants. While our present study does not allow for disambiguating precisely the relative contribution of adaptation and prediction error processing to the observed mismatch responses, it demonstrates that MMN-like potentials can be obtained in awake and unrestrained rats. PMID:23646197

  16. A system for recording neural activity chronically and simultaneously from multiple cortical and subcortical regions in nonhuman primates.

    PubMed

    Feingold, Joseph; Desrochers, Theresa M; Fujii, Naotaka; Harlan, Ray; Tierney, Patrick L; Shimazu, Hideki; Amemori, Ken-Ichi; Graybiel, Ann M

    2012-04-01

    A major goal of neuroscience is to understand the functions of networks of neurons in cognition and behavior. Recent work has focused on implanting arrays of ∼100 immovable electrodes or smaller numbers of individually adjustable electrodes, designed to target a few cortical areas. We have developed a recording system that allows the independent movement of hundreds of electrodes chronically implanted in several cortical and subcortical structures. We have tested this system in macaque monkeys, recording simultaneously from up to 127 electrodes in 14 brain regions for up to one year at a time. A key advantage of the system is that it can be used to sample different combinations of sites over prolonged periods, generating multiple snapshots of network activity from a single implant. Used in conjunction with microstimulation and injection methods, this versatile system represents a powerful tool for studying neural network activity in the primate brain. PMID:22170970

  17. A system for recording neural activity chronically and simultaneously from multiple cortical and subcortical regions in nonhuman primates

    PubMed Central

    Feingold, Joseph; Desrochers, Theresa M.; Fujii, Naotaka; Harlan, Ray; Tierney, Patrick L.; Shimazu, Hideki; Amemori, Ken-ichi

    2012-01-01

    A major goal of neuroscience is to understand the functions of networks of neurons in cognition and behavior. Recent work has focused on implanting arrays of ∼100 immovable electrodes or smaller numbers of individually adjustable electrodes, designed to target a few cortical areas. We have developed a recording system that allows the independent movement of hundreds of electrodes chronically implanted in several cortical and subcortical structures. We have tested this system in macaque monkeys, recording simultaneously from up to 127 electrodes in 14 brain regions for up to one year at a time. A key advantage of the system is that it can be used to sample different combinations of sites over prolonged periods, generating multiple snapshots of network activity from a single implant. Used in conjunction with microstimulation and injection methods, this versatile system represents a powerful tool for studying neural network activity in the primate brain. PMID:22170970

  18. A time-frequency analysis of the dynamics of cortical networks of sleep spindles from MEG-EEG recordings

    PubMed Central

    Zerouali, Younes; Lina, Jean-Marc; Sekerovic, Zoran; Godbout, Jonathan; Dube, Jonathan; Jolicoeur, Pierre; Carrier, Julie

    2014-01-01

    Sleep spindles are a hallmark of NREM sleep. They result from a widespread thalamo-cortical loop and involve synchronous cortical networks that are still poorly understood. We investigated whether brain activity during spindles can be characterized by specific patterns of functional connectivity among cortical generators. For that purpose, we developed a wavelet-based approach aimed at imaging the synchronous oscillatory cortical networks from simultaneous MEG-EEG recordings. First, we detected spindles on the EEG and extracted the corresponding frequency-locked MEG activity under the form of an analytic ridge signal in the time-frequency plane (Zerouali et al., 2013). Secondly, we performed source reconstruction of the ridge signal within the Maximum Entropy on the Mean framework (Amblard et al., 2004), yielding a robust estimate of the cortical sources producing observed oscillations. Lastly, we quantified functional connectivity among cortical sources using phase-locking values. The main innovations of this methodology are (1) to reveal the dynamic behavior of functional networks resolved in the time-frequency plane and (2) to characterize functional connectivity among MEG sources through phase interactions. We showed, for the first time, that the switch from fast to slow oscillatory mode during sleep spindles is required for the emergence of specific patterns of connectivity. Moreover, we show that earlier synchrony during spindles was associated with mainly intra-hemispheric connectivity whereas later synchrony was associated with global long-range connectivity. We propose that our methodology can be a valuable tool for studying the connectivity underlying neural processes involving sleep spindles, such as memory, plasticity or aging. PMID:25389381

  19. Minimally invasive endovascular stent-electrode array for high-fidelity, chronic recordings of cortical neural activity.

    PubMed

    Oxley, Thomas J; Opie, Nicholas L; John, Sam E; Rind, Gil S; Ronayne, Stephen M; Wheeler, Tracey L; Judy, Jack W; McDonald, Alan J; Dornom, Anthony; Lovell, Timothy J H; Steward, Christopher; Garrett, David J; Moffat, Bradford A; Lui, Elaine H; Yassi, Nawaf; Campbell, Bruce C V; Wong, Yan T; Fox, Kate E; Nurse, Ewan S; Bennett, Iwan E; Bauquier, Sébastien H; Liyanage, Kishan A; van der Nagel, Nicole R; Perucca, Piero; Ahnood, Arman; Gill, Katherine P; Yan, Bernard; Churilov, Leonid; French, Christopher R; Desmond, Patricia M; Horne, Malcolm K; Kiers, Lynette; Prawer, Steven; Davis, Stephen M; Burkitt, Anthony N; Mitchell, Peter J; Grayden, David B; May, Clive N; O'Brien, Terence J

    2016-03-01

    High-fidelity intracranial electrode arrays for recording and stimulating brain activity have facilitated major advances in the treatment of neurological conditions over the past decade. Traditional arrays require direct implantation into the brain via open craniotomy, which can lead to inflammatory tissue responses, necessitating development of minimally invasive approaches that avoid brain trauma. Here we demonstrate the feasibility of chronically recording brain activity from within a vein using a passive stent-electrode recording array (stentrode). We achieved implantation into a superficial cortical vein overlying the motor cortex via catheter angiography and demonstrate neural recordings in freely moving sheep for up to 190 d. Spectral content and bandwidth of vascular electrocorticography were comparable to those of recordings from epidural surface arrays. Venous internal lumen patency was maintained for the duration of implantation. Stentrodes may have wide ranging applications as a neural interface for treatment of a range of neurological conditions. PMID:26854476

  20. 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. PMID:22254801

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

    PubMed Central

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

    2014-01-01

    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. PMID:22254801

  2. Cortical representation of the human hand assessed by two levels of high-resolution EEG recordings.

    PubMed

    Houzé, Bérengère; Perchet, Caroline; Magnin, Michel; Garcia-Larrea, Luis

    2011-11-01

    Increasing interest in cortical plasticity has prompted the growing use of somatosensory evoked potentials (SEPs) to estimate changes in the cortical representation of body regions. Here, we tested the effect of different sites of hand stimulation and of the density of spatial sampling in the quality of estimation of somatosensory sources. Sources of two SEP components from the primary somatosensory cortex (N20/P20 and P45) were estimated using two levels of spatial sampling (64- vs. 128-channel) and stimulation of four distal sites in the upper limbs, including single digits (first vs. fifth) and distal nerves with comparable cortical projection (superficial branch of the radial nerve and distal ulnar nerve). The most robust separation of somatosensory sources was achieved by comparing the cortical representations of the first digit and the distal ulnar nerve territories on the N20/P20 component of SEPs. Although both the 64- and the 128-electrode montages correctly discriminated these two areas, only the 128-electrode montage was able to significantly separate sources in the other cases, notably when using first versus fifth digit stimulation. Trustworthy distinction of cortical representations was not obtainable when using the P45 component, probably because of greater activation volume, radial orientation of sources in areas 1-2 and increased variability with attention and vigilance. Assessment of tangential SEP components to stimulation of first digit versus ulnar nerve appears the best option to assess plastic somatosensory changes, especially when using relatively low-electrode sampling. PMID:21246666

  3. Real-time Recordings of Migrating Cortical Neurons from GFP and Cre Recombinase Expressing Mice.

    PubMed

    Tielens, Sylvia; Godin, Juliette D; Nguyen, Laurent

    2016-01-01

    The cerebral cortex is one of the most intricate regions of the brain that requires elaborate cell migration patterns for its development. Experimental observations show that projection neurons migrate radially within the cortical wall, whereas interneurons migrate along multiple tangential paths to reach the developing cortex. Tight regulation of the cell migration processes ensures proper positioning and functional integration of neurons to specific cerebral cortical circuits. Disruption of neuronal migration often leads to cortical dysfunction and/or malformation associated with neurological disorders. Unveiling the molecular control of neuron migration is thus fundamental to understanding the physiological or pathological development of the cerebral cortex. In this unit, protocols allowing detailed analysis of patterns of migration of both interneurons and projection neurons under different experimental conditions (i.e., loss or gain of function) are presented. PMID:26729032

  4. Local domains of motor cortical activity revealed by fiber-optic calcium recordings in behaving nonhuman primates.

    PubMed

    Adelsberger, Helmuth; Zainos, Antonio; Alvarez, Manuel; Romo, Ranulfo; Konnerth, Arthur

    2014-01-01

    Brain mapping experiments involving electrical microstimulation indicate that the primary motor cortex (M1) directly regulates muscle contraction and thereby controls specific movements. Possibly, M1 contains a small circuit "map" of the body that is formed by discrete local networks that code for specific movements. Alternatively, movements may be controlled by distributed, larger-scale overlapping circuits. Because of technical limitations, it remained unclear how movement-determining circuits are organized in M1. Here we introduce a method that allows the functional mapping of small local neuronal circuits in awake behaving nonhuman primates. For this purpose, we combined optic-fiber-based calcium recordings of neuronal activity and cortical microstimulation. The method requires targeted bulk loading of synthetic calcium indicators (e.g., OGB-1 AM) for the staining of neuronal microdomains. The tip of a thin (200 µm) optical fiber can detect the coherent activity of a small cluster of neurons, but is insensitive to the asynchronous activity of individual cells. By combining such optical recordings with microstimulation at two well-separated sites of M1, we demonstrate that local cortical activity was tightly associated with distinct and stereotypical simple movements. Increasing stimulation intensity increased both the amplitude of the movements and the level of neuronal activity. Importantly, the activity remained local, without invading the recording domain of the second optical fiber. Furthermore, there was clear response specificity at the two recording sites in a trained behavioral task. Thus, the results provide support for movement control in M1 by local neuronal clusters that are organized in discrete cortical domains. PMID:24344287

  5. Optical Recording of Retinal and Visual Cortical Responses Evoked by Electrical Stimulation on the Retina

    NASA Astrophysics Data System (ADS)

    Osanai, Makoto; Sakaehara, Haruko; Sawai, Hajime; Song, Wen-Jie; Yagi, Tetsuya

    To develop a retinal prosthesis for blind patients using an implanted multielectrode array, it is important to study the response properties of retinal ganglion cells and of the visual cortex to localized retinal electrical stimulation. Optical imaging can reveal the spatio-temporal properties of neuronal activity. Therefore, we conducted a calcium imaging study to investigate response properties to local current stimulation in frog retinas, and a membrane potential imaging study to explore the visual cortical responses to retinal stimulation in guinea pigs. In the retina, local current stimuli evoked transient responses in the ganglion cells located near the stimulus electrode. The spatial pattern of the responding area was altered by changing the location of the stimulation. Local electrical stimulation to the retina also caused transient responses in the visual cortex. The responding cortical areas in the primary visual cortex were localized. A spatially different cortical response was observed to stimulation of a different position on the retina. These results suggest that the imaging study has great potential in revealing the spatio-temporal properties of the neuronal response for the retinal prosthesis.

  6. Non-invasive long-term recordings of cortical 'direct current' (DC-) activity in humans using magnetoencephalography.

    PubMed

    Mackert, B M; Wübbeler, G; Burghoff, M; Marx, P; Trahms, L; Curio, G

    1999-10-01

    Recently, biomagnetic fields below 0.1 Hz arising from nerve or muscle injury currents have been measured non-invasively using superconducting quantum interference devices (SQUIDs). Here we report first long-term recordings of cortical direct current (DC) fields in humans based on a horizontal modulation (0.4 Hz) of the body and, respectively, head position beneath the sensor array: near-DC fields with amplitudes between 90 and 540 fT were detected in 5/5 subjects over the auditory cortex throughout prolonged stimulation periods (here: 30 s) during which subjects were listening to concert music. These results prove the feasibility to record non-invasively low amplitude near-DC magnetic fields of the human brain and open the perspective for studies on DC-phenomena in stroke, such as anoxic depolarization or periinfarct depolarization, and in migraine patients. PMID:10515183

  7. Fabrication and testing of microelectrodes for small-field cortical surface recordings.

    PubMed

    Kitzmiller, Joseph; Beversdorf, David; Hansford, Derek

    2006-03-01

    A microfabrication approach to produce a microelectrode array that is suitable for use with human patients has been developed. The device is comprised of materials that are consistent with those of clinically used macroelectrodes (platinum electrode contacts suspended within a biomedical grade polydimethylsiloxane, PDMS). Photolithography, metal deposition, wire bonding, and PDMS encapsulation were used to fabricate the device. Cytotoxicity testing with both mammalian and human cortical cells suggests that the device is suitable for use with human patients and implementation of the device in animal studies revealed that reliable evoked potentials could be acquired with the designed spatial resolution. PMID:16491335

  8. Prefrontal cortical recordings with biomorphic MEAs reveal complex columnar-laminar microcircuits for BCI/BMI implementation

    PubMed Central

    Opris, Ioan; Fuqua, Joshua L; Gerhardt, Greg A.; Hampson, Robert E.; Deadwyler, Sam A.

    2015-01-01

    The mammalian prefrontal cortex known as the seat of high brain functions uses a six layer distribution of minicolumnar neurons to coordinate the integration of sensory information and the selection of relevant signals for goal driven behavior. To reveal the complex functionality of these columnar microcircuits we employed simultaneous recordings with several configurations of biomorphic microelectrode arrays (MEAs) within cortical layers in adjacent minicolumns, in four nohuman primates (NHPs) performing a delayed match-to-sample (DMS) visual discrimination task. We examined: 1) the functionality of inter-laminar, and inter-columnar interactions between pairs of cells in the same or different minicolumns by use of normalized cross-correlation histograms (CCH), 2) the modulation of Glutamate concentration in layer 2/3, and 3) the potential interactions within these microcircuits. The results demonstrate that neurons in both infra-granular and supra-granular layers interact through inter-laminar loops, as well as through intra-laminar to produce behavioral response signals. These results provide new insights into the manner in which prefrontal cortical microcircuitry integrates sensory stimuli used to provide behaviorally relevant signals that may be implemented in brain computer/machine interfaces (BCI/BMIs) during performance of the task. PMID:24954713

  9. Virtual Electrode Recording Tool for EXtracellular potentials (VERTEX): comparing multi-electrode recordings from simulated and biological mammalian cortical tissue.

    PubMed

    Tomsett, Richard J; Ainsworth, Matt; Thiele, Alexander; Sanayei, Mehdi; Chen, Xing; Gieselmann, Marc A; Whittington, Miles A; Cunningham, Mark O; Kaiser, Marcus

    2015-07-01

    Local field potentials (LFPs) sampled with extracellular electrodes are frequently used as a measure of population neuronal activity. However, relating such measurements to underlying neuronal behaviour and connectivity is non-trivial. To help study this link, we developed the Virtual Electrode Recording Tool for EXtracellular potentials (VERTEX). We first identified a reduced neuron model that retained the spatial and frequency filtering characteristics of extracellular potentials from neocortical neurons. We then developed VERTEX as an easy-to-use Matlab tool for simulating LFPs from large populations (>100,000 neurons). A VERTEX-based simulation successfully reproduced features of the LFPs from an in vitro multi-electrode array recording of macaque neocortical tissue. Our model, with virtual electrodes placed anywhere in 3D, allows direct comparisons with the in vitro recording setup. We envisage that VERTEX will stimulate experimentalists, clinicians, and computational neuroscientists to use models to understand the mechanisms underlying measured brain dynamics in health and disease. PMID:24863422

  10. Micro-electrode array recordings reveal reductions in both excitation and inhibition in cultured cortical neuron networks lacking Shank3.

    PubMed

    Lu, C; Chen, Q; Zhou, T; Bozic, D; Fu, Z; Pan, J Q; Feng, G

    2016-02-01

    Numerous risk genes have recently been implicated in susceptibility to autism and schizophrenia. Translating such genetic findings into disease-relevant neurobiological mechanisms is challenging due to the lack of throughput assays that can be used to assess their functions on an appropriate scale. To address this issue, we explored the feasibility of using a micro-electrode array (MEA) as a potentially scalable assay to identify the electrical network phenotypes associated with risk genes. We first characterized local and global network firing in cortical neurons with MEAs, and then developed methods to analyze the alternation between the network active period (NAP) and the network inactive period (NIP), each of which lasts tens of seconds. We then evaluated the electric phenotypes of neurons derived from Shank3 knockout (KO) mice. Cortical neurons cultured on MEAs displayed a rich repertoire of spontaneous firing, and Shank3 deletion led to reduced firing activity. Enhancing excitation with CX546 rescued the deficit in the spike rate in the Shank3 KO network. In addition, the Shank3 KO network produced a shorter NIP, and this altered network firing pattern was normalized by clonazepam, a positive modulator of the GABAA receptor. MEA recordings revealed electric phenotypes that displayed altered excitation and inhibition in the network lacking Shank3. Thus, our study highlights MEAs as an experimental framework for measuring multiple robust neurobiological end points in dynamic networks and as an assay system that could be used to identify electric phenotypes in cultured neuronal networks and to analyze additional risk genes identified in psychiatric genetics. PMID:26598066

  11. Decoding grating orientation from microelectrode array recordings in monkey cortical area V4.

    PubMed

    Manyakov, Nikolay V; Van Hulle, Marc M

    2010-04-01

    We propose an invasive brain-machine interface (BMI) that decodes the orientation of a visual grating from spike train recordings made with a 96 microelectrodes array chronically implanted into the prelunate gyrus (area V4) of a rhesus monkey. The orientation is decoded irrespective of the grating's spatial frequency. Since pyramidal cells are less prominent in visual areas, compared to (pre)motor areas, the recordings contain spikes with smaller amplitudes, compared to the noise level. Hence, rather than performing spike decoding, feature selection algorithms are applied to extract the required information for the decoder. Two types of feature selection procedures are compared, filter and wrapper. The wrapper is combined with a linear discriminant analysis classifier, and the filter is followed by a radial-basis function support vector machine classifier. In addition, since we have a multiclass classification problen, different methods for combining pairwise classifiers are compared. PMID:20411593

  12. Estimation of the cortical activity from simultaneous multi-subject recordings during the prisoner's dilemma.

    PubMed

    Astolfi, L; Cincotti, F; Mattia, D; De Vico Fallani, F; Salinari, S; Marciani, M G; Wilke, C; Doud, A; Yuan, H; He, B; Babiloni, F

    2009-01-01

    One of the most challenging questions open in Neuroscience today is the characterization of the brain responses during social interaction. A major limitation of the approaches used in most of the studies performed so far is that only one of the participating brains is measured each time. The "interaction" between cooperating, competing or communicating brains is thus not measured directly, but inferred by independent observations aggregated by cognitive models and assumptions that link behavior and neural activation. In this paper, we present the results of the simultaneous neuroelectric recording of 5 couples of subjects engaged in cooperative games (EEG hyperscanning). The simultaneous recordings of couples of interacting subjects allows to observe and model directly the neural signature of human interactions in order to understand the cerebral processes generating and generated by social cooperation or competition. We used a paradigm called Prisoner's dilemma derived from the game theory. Results collected in a population of 10 subjects suggested that the most consistently activated structure in social interaction paradigms is the orbitofrontal region (roughly described by the Brodmann area 10) during the condition of competition. PMID:19964016

  13. Cortical gamma-oscillations modulated by visuomotor tasks -Intracranial recording in patients with epilepsy-

    PubMed Central

    Nagasawa, Tetsuro; Rothermel, Robert; Juhász, Csaba; Nishida, Masaaki; Sood, Sandeep; Asano, Eishi

    2010-01-01

    SUMMARY We determined how visuomotor tasks modulated gamma-oscillations on electrocorticography in epileptic patients who underwent epilepsy surgery. Each visual-cue consisted of either a sentence or hand gesture instructing the subject to press or not to press the button. Regardless of the recorded hemisphere, viewing sentence and gesture cues elicited gamma-augmentation sequentially in the lateral-polar occipital and inferior occipital-temporal areas; subsequently, button-press movement elicited gamma-augmentation in the Rolandic area. The magnitudes of gamma-augmentation in the Rolandic and inferior occipital-temporal areas were larger when the hand contralateral to the recorded hemisphere was used for motor responses. A double dissociation was found in the left inferior occipital-temporal cortex in one subject; the lateral portion had greater gamma-augmentation elicited by a sentence-cue, whereas the medial portion had greater gamma-augmentation elicited by a gesture-cue. The present study has increased our understanding of the physiology of the human visuomotor system. PMID:20580900

  14. Wireless simultaneous stimulation-and-recording device to train cortical circuits in somatosensory cortex.

    PubMed

    Ramshur, John T; de Jongh Curry, Amy L; Waters, Robert S

    2014-01-01

    We describe for the first time the design, implementation, and testing of a telemetry controlled simultaneous stimulation and recording device (SRD) to deliver chronic intercortical microstimulation (ICMS) to physiologically identified sites in rat somatosensory cortex (SI) and test hypotheses that chronic ICMS strengthens interhemispheric pathways and leads to functional reorganization in the enhanced cortex. The SRD is a custom embedded device that uses the Cypress Semiconductor's programmable system on a chip (PSoC) that is remotely controlled via Bluetooth. The SRC can record single or multiunit responses from any two of 12 available inputs at 1-15 ksps per channel and simultaneously deliver stimulus pulses (0-255 μA; 10 V compliance) to two user selectable electrodes using monophasic, biphasic, or pseudophasic stimulation waveforms (duration: 0-5 ms, inter-phase interval: 0-5 ms, frequency: 0.1-5 s, delay: 0-10 ms). The SRD was bench tested and validated in vivo in a rat animal model. PMID:25569987

  15. 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. PMID:25109901

  16. Cortical activity and functional hyperconnectivity by simultaneous EEG recordings from interacting couples of professional pilots.

    PubMed

    Astolfi, L; Toppi, J; Borghini, G; Vecchiato, G; He, E J; Roy, A; Cincotti, F; Salinari, S; Mattia, D; He, B; Babiloni, F

    2012-01-01

    Controlling an aircraft during a flight is a compelling condition, which requires a strict and well coded interaction between the crew. The interaction level between the Captain and the First Officer changes during the flight, ranging from a maximum (during takeoff and landing, as well as in case of a failure of the instrumentation or other emergency situations) to a minimum during quiet mid-flight. In this study, our aim is to investigate the neural correlates of different kinds and levels of interaction between couples of professional crew members by means of the innovative technique called brain hyperscanning, i.e. the simultaneous recording of the hemodynamic or neuroelectrical activity of different human subjects involved in interaction tasks. This approach allows the observation and modeling of the neural signature specifically dependent on the interaction between subjects, and, even more interestingly, of the functional links existing between the brain activities of the subjects interacting together. In this EEG hyperscanning study, different phases of a flight were reproduced in a professional flight simulator, which allowed, on one side, to reproduce the ecological setting of a real flight, and, on the other, to keep under control the different levels of interaction induced in the crew by means of systematic and simulated failures of the aircraft instrumentation. Results of the procedure of linear inverse estimation, together with functional hyperconnectivity estimated by means of Partial Directed Coherence, showed a dense network of connections between the activity in the two brains in the takeoff and landing phases, when the cooperation between the crew is maximal, while conversely no significant links were shown during the phases in which the activity of the two pilots was independent. PMID:23366990

  17. 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

  18. 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

  19. The Touch and Zap Method for In Vivo Whole-Cell Patch Recording of Intrinsic and Visual Responses of Cortical Neurons and Glial Cells

    PubMed Central

    Schramm, Adrien E.; Marinazzo, Daniele; Gener, Thomas; Graham, Lyle J.

    2014-01-01

    Whole-cell patch recording is an essential tool for quantitatively establishing the biophysics of brain function, particularly in vivo. This method is of particular interest for studying the functional roles of cortical glial cells in the intact brain, which cannot be assessed with extracellular recordings. Nevertheless, a reasonable success rate remains a challenge because of stability, recording duration and electrical quality constraints, particularly for voltage clamp, dynamic clamp or conductance measurements. To address this, we describe “Touch and Zap”, an alternative method for whole-cell patch clamp recordings, with the goal of being simpler, quicker and more gentle to brain tissue than previous approaches. Under current clamp mode with a continuous train of hyperpolarizing current pulses, seal formation is initiated immediately upon cell contact, thus the “Touch”. By maintaining the current injection, whole-cell access is spontaneously achieved within seconds from the cell-attached configuration by a self-limited membrane electroporation, or “Zap”, as seal resistance increases. We present examples of intrinsic and visual responses of neurons and putative glial cells obtained with the revised method from cat and rat cortices in vivo. Recording parameters and biophysical properties obtained with the Touch and Zap method compare favourably with those obtained with the traditional blind patch approach, demonstrating that the revised approach does not compromise the recorded cell. We find that the method is particularly well-suited for whole-cell patch recordings of cortical glial cells in vivo, targeting a wider population of this cell type than the standard method, with better access resistance. Overall, the gentler Touch and Zap method is promising for studying quantitative functional properties in the intact brain with minimal perturbation of the cell's intrinsic properties and local network. Because the Touch and Zap method is performed semi

  20. Recording human electrocorticographic (ECoG) signals for neuroscientific research and real-time functional cortical mapping.

    PubMed

    Hill, N Jeremy; Gupta, Disha; Brunner, Peter; Gunduz, Aysegul; Adamo, Matthew A; Ritaccio, Anthony; Schalk, Gerwin

    2012-01-01

    Neuroimaging studies of human cognitive, sensory, and motor processes are usually based on noninvasive techniques such as electroencephalography (EEG), magnetoencephalography or functional magnetic-resonance imaging. These techniques have either inherently low temporal or low spatial resolution, and suffer from low signal-to-noise ratio and/or poor high-frequency sensitivity. Thus, they are suboptimal for exploring the short-lived spatio-temporal dynamics of many of the underlying brain processes. In contrast, the invasive technique of electrocorticography (ECoG) provides brain signals that have an exceptionally high signal-to-noise ratio, less susceptibility to artifacts than EEG, and a high spatial and temporal resolution (i.e., <1 cm/<1 millisecond, respectively). ECoG involves measurement of electrical brain signals using electrodes that are implanted subdurally on the surface of the brain. Recent studies have shown that ECoG amplitudes in certain frequency bands carry substantial information about task-related activity, such as motor execution and planning, auditory processing and visual-spatial attention. Most of this information is captured in the high gamma range (around 70-110 Hz). Thus, gamma activity has been proposed as a robust and general indicator of local cortical function. ECoG can also reveal functional connectivity and resolve finer task-related spatial-temporal dynamics, thereby advancing our understanding of large-scale cortical processes. It has especially proven useful for advancing brain-computer interfacing (BCI) technology for decoding a user's intentions to enhance or improve communication and control. Nevertheless, human ECoG data are often hard to obtain because of the risks and limitations of the invasive procedures involved, and the need to record within the constraints of clinical settings. Still, clinical monitoring to localize epileptic foci offers a unique and valuable opportunity to collect human ECoG data. We describe our

  1. Recording Human Electrocorticographic (ECoG) Signals for Neuroscientific Research and Real-time Functional Cortical Mapping

    PubMed Central

    Hill, N. Jeremy; Gupta, Disha; Brunner, Peter; Gunduz, Aysegul; Adamo, Matthew A.; Ritaccio, Anthony; Schalk, Gerwin

    2012-01-01

    Neuroimaging studies of human cognitive, sensory, and motor processes are usually based on noninvasive techniques such as electroencephalography (EEG), magnetoencephalography or functional magnetic-resonance imaging. These techniques have either inherently low temporal or low spatial resolution, and suffer from low signal-to-noise ratio and/or poor high-frequency sensitivity. Thus, they are suboptimal for exploring the short-lived spatio-temporal dynamics of many of the underlying brain processes. In contrast, the invasive technique of electrocorticography (ECoG) provides brain signals that have an exceptionally high signal-to-noise ratio, less susceptibility to artifacts than EEG, and a high spatial and temporal resolution (i.e., <1 cm/<1 millisecond, respectively). ECoG involves measurement of electrical brain signals using electrodes that are implanted subdurally on the surface of the brain. Recent studies have shown that ECoG amplitudes in certain frequency bands carry substantial information about task-related activity, such as motor execution and planning1, auditory processing2 and visual-spatial attention3. Most of this information is captured in the high gamma range (around 70-110 Hz). Thus, gamma activity has been proposed as a robust and general indicator of local cortical function1-5. ECoG can also reveal functional connectivity and resolve finer task-related spatial-temporal dynamics, thereby advancing our understanding of large-scale cortical processes. It has especially proven useful for advancing brain-computer interfacing (BCI) technology for decoding a user's intentions to enhance or improve communication6 and control7. Nevertheless, human ECoG data are often hard to obtain because of the risks and limitations of the invasive procedures involved, and the need to record within the constraints of clinical settings. Still, clinical monitoring to localize epileptic foci offers a unique and valuable opportunity to collect human ECoG data. We describe

  2. "Real-time" imaging of cortical and subcortical sites of cardiovascular control: concurrent recordings of sympathetic nerve activity and fMRI in awake subjects.

    PubMed

    Macefield, Vaughan G; Henderson, Luke A

    2016-09-01

    We review our approach to functionally identifying cortical and subcortical areas involved in the generation of spontaneous fluctuations in sympathetic outflow to muscle or skin. We record muscle sympathetic nerve activity (MSNA) or skin sympathetic nerve activity (SSNA), via a tungsten microelectrode inserted percutaneously into the common peroneal nerve, at the same time as performing functional magnetic resonance imaging (fMRI) of the brain. By taking advantage of the neurovascular coupling delay associated with BOLD (blood oxygen level dependent) fMRI, and the delay associated with conduction of a burst of sympathetic impulses to the peripheral recording site, we can identify structures in which BOLD signal intensity covaries with MSNA or SSNA. Using this approach, we found MSNA-coupled increases in BOLD signal intensity in the mid-insula and dorsomedial hypothalamus on the left side, and in dorsolateral prefrontal cortex, posterior cingulate cortex, precuneus, ventromedial hypothalamus and rostral ventrolateral medulla on both sides. Conversely, spontaneous bursts of SSNA were positively correlated with BOLD signal intensity in the ventromedial thalamus and posterior insula on the left side, and in the anterior insula, orbitofrontal cortex and frontal cortex on the right side, and in the mid-cingulate cortex and precuneus on both sides. Inverse relationships were observed between MSNA and BOLD signal intensity in the right ventral insula, nucleus tractus solitarius and caudal ventrolateral medulla, and between SSNA and signal intensity in the left orbitofrontal cortex. These results emphasize the contributions of cortical regions of the brain to sympathetic outflow in awake human subjects, and the extensive interactions between cortical and subcortical regions in the ongoing regulation of sympathetic nerve activity to muscle and skin in awake human subjects. PMID:27334958

  3. Voxel-based Morphometric MRI Post-processing in MRI-negative Focal Cortical Dysplasia Followed by Simultaneously-recorded MEG and Stereo-EEG

    PubMed Central

    Wang, Z. Irene; Jones, Stephen E.; Ristic, Aleksandar J.; Wong, Chong; Kakisaka, Yosuke; Jin, Kazutaka; Schneider, Felix; Gonzalez-Martinez, Jorge A.; Mosher, John C.; Nair, Dileep; Burgess, Richard C.; Najm, Imad M.

    2012-01-01

    Summary We aim to report on the usefulness of a voxel-based morphometric MRI postprocessing technique in detecting subtle epileptogenic structural lesion. The MRI post-processing technique was implemented in a morphometric analysis program (MAP), in a 30-year-old male with pharmacoresistant focal epilepsy and negative MRI. MAP gray-white matter junction file facilitated the identification of a suspicious structural lesion in the right frontal opercular area. The electrophysiological data by simultaneously recorded stereo-EEG and MEG confirmed the epileptogenicity of the underlying subtle structural lesion. The patient underwent a limited right frontal opercular resection, which completely included the area detected by MAP. Surgical pathology revealed focal cortical dysplasia (FCD) type IIb. Postoperatively the patient has been seizure-free for 2 years. This study demonstrates that MAP has promise in increasing the diagnostic yield of MRI reading in challenging patients with “non-lesional” MRIs. The clinical relevance and epileptogenicity of MAP abnormalities in patients with epilepsy have not been investigated systematically; therefore it is important to confirm their pertinence by performing electrophysiological recordings. When confirmed to be epileptogenic, such MAP abnormalities may reflect an underlying subtle cortical dysplasia whose complete resection can lead to seizure-free outcome. PMID:22391138

  4. Ketamine Dysregulates the Amplitude and Connectivity of High-Frequency Oscillations in Cortical-Subcortical Networks in Humans: Evidence From Resting-State Magnetoencephalography-Recordings.

    PubMed

    Rivolta, Davide; Heidegger, Tonio; Scheller, Bertram; Sauer, Andreas; Schaum, Michael; Birkner, Katharina; Singer, Wolf; Wibral, Michael; Uhlhaas, Peter J

    2015-09-01

    Hypofunctioning of the N-methyl-D-aspartate receptor (NMDA-R) has been prominently implicated in the pathophysiology of schizophrenia (ScZ). The current study tested the effects of ketamine, a dissociative anesthetic and NMDA-R antagonist, on resting-state activity recorded with magnetoencephalography (MEG) in healthy volunteers. In a single-blind cross-over design, each participant (n = 12) received, on 2 different sessions, a subanesthetic dose of S-ketamine (0.006 mg/Kg) and saline injection. MEG-data were analyzed at sensor- and source-level in the beta (13-30 Hz) and gamma (30-90 Hz) frequency ranges. In addition, connectivity analysis at source-level was performed using transfer entropy (TE). Ketamine increased gamma-power while beta-band activity was decreased. Specifically, elevated 30-90 Hz activity was pronounced in subcortical (thalamus and hippocampus) and cortical (frontal and temporal cortex) regions, whilst reductions in beta-band power were localized to the precuneus, cerebellum, anterior cingulate, temporal and visual cortex. TE analysis demonstrated increased information transfer in a thalamo-cortical network after ketamine administration. The findings are consistent with the pronounced dysregulation of high-frequency oscillations following the inhibition of NMDA-R in animal models of ScZ as well as with evidence from electroencephalogram-data in ScZ-patients and increased functional connectivity during early illness stages. Moreover, our data highlight the potential contribution of thalamo-cortical connectivity patterns towards ketamine-induced neuronal dysregulation, which may be relevant for the understanding of ScZ as a disorder of disinhibition of neural circuits. PMID:25987642

  5. Large-Scale, High-Resolution Multielectrode-Array Recording Depicts Functional Network Differences of Cortical and Hippocampal Cultures

    PubMed Central

    Ito, Shinya; Yeh, Fang-Chin; Hiolski, Emma; Rydygier, Przemyslaw; Gunning, Deborah E.; Hottowy, Pawel; Timme, Nicholas; Litke, Alan M.; Beggs, John M.

    2014-01-01

    Understanding the detailed circuitry of functioning neuronal networks is one of the major goals of neuroscience. Recent improvements in neuronal recording techniques have made it possible to record the spiking activity from hundreds of neurons simultaneously with sub-millisecond temporal resolution. Here we used a 512-channel multielectrode array system to record the activity from hundreds of neurons in organotypic cultures of cortico-hippocampal brain slices from mice. To probe the network structure, we employed a wavelet transform of the cross-correlogram to categorize the functional connectivity in different frequency ranges. With this method we directly compare, for the first time, in any preparation, the neuronal network structures of cortex and hippocampus, on the scale of hundreds of neurons, with sub-millisecond time resolution. Among the three frequency ranges that we investigated, the lower two frequency ranges (gamma (30–80 Hz) and beta (12–30 Hz) range) showed similar network structure between cortex and hippocampus, but there were many significant differences between these structures in the high frequency range (100–1000 Hz). The high frequency networks in cortex showed short tailed degree-distributions, shorter decay length of connectivity density, smaller clustering coefficients, and positive assortativity. Our results suggest that our method can characterize frequency dependent differences of network architecture from different brain regions. Crucially, because these differences between brain regions require millisecond temporal scales to be observed and characterized, these results underscore the importance of high temporal resolution recordings for the understanding of functional networks in neuronal systems. PMID:25126851

  6. Cortical motion deafness.

    PubMed

    Ducommun, Christine Y; Michel, Christoph M; Clarke, Stephanie; Adriani, Michela; Seeck, Margitta; Landis, Theodor; Blanke, Olaf

    2004-09-16

    The extent to which the auditory system, like the visual system, processes spatial stimulus characteristics such as location and motion in separate specialized neuronal modules or in one homogeneously distributed network is unresolved. Here we present a patient with a selective deficit for the perception and discrimination of auditory motion following resection of the right anterior temporal lobe and the right posterior superior temporal gyrus (STG). Analysis of stimulus identity and location within the auditory scene remained intact. In addition, intracranial auditory evoked potentials, recorded preoperatively, revealed motion-specific responses selectively over the resected right posterior STG, and electrical cortical stimulation of this region was experienced by the patient as incoming moving sounds. Collectively, these data present a patient with cortical motion deafness, providing evidence that cortical processing of auditory motion is performed in a specialized module within the posterior STG. PMID:15363389

  7. Maturation of cortical auditory evoked potentials (CAEPs) to speech recorded from frontocentral and temporal sites: three months to eight years of age

    PubMed Central

    Yu, Yan H.; Wagner, Monica

    2014-01-01

    The goal of the current analysis was to examine the maturation of cortical auditory evoked potentials (CAEPs) from three months of age to eight years of age. The superior frontal positive-negative-positive sequence (P1, N2, P2) and the temporal site, negative-positive-negative sequence (possibly, Na, Ta, Tb of the T-complex) were examined. Event-related potentials were recorded from 63 scalp sites to a 250- ms vowel. Amplitude and latency of peaks were measured at left and right frontal sites (near Fz) and at left and right temporal sites (T7 and T8). In addition the largest peak (typically corresponding to P1) was selected from global field power (GFP). The results revealed a large positive peak (P1) easily identified at frontal sites across all ages. The N2 emerged after 6 months of age and the following P2 between 8 and 30 months of age. The latencies of these peaks decreased exponentially with the most rapid decrease observed for P1. For amplitude, only P1 showed a clear relationship with age, becoming more positive in a somewhat linear fashion. At the temporal sites only a negative peak, which might be Na, was clearly observed at both left and right sites in children older than 14 months and peaking between 100 and 200 ms. P1 measures at frontal sites and Na peak latencies were moderately correlated. The temporal negative peak latency showed a different maturational timecourse (linear in nature) than the P1 peak, suggesting at least partial independence. Distinct Ta (positive) and Tb (negative) peaks, following Na and peaking between 120 and 220 ms were not consistently found in most age groups of children, except Ta which was present in 7 year olds. Future research, which includes manipulation of stimulus factors, and use of modeling techniques will be needed to explain the apparent, protracted maturation of the temporal site measures in the current study. PMID:25219893

  8. Maturation of cortical auditory evoked potentials (CAEPs) to speech recorded from frontocentral and temporal sites: three months to eight years of age.

    PubMed

    Shafer, Valerie L; Yu, Yan H; Wagner, Monica

    2015-02-01

    The goal of the current analysis was to examine the maturation of cortical auditory evoked potentials (CAEPs) from three months of age to eight years of age. The superior frontal positive-negative-positive sequence (P1, N2, P2) and the temporal site, negative-positive-negative sequence (possibly, Na, Ta, Tb of the T-complex) were examined. Event-related potentials were recorded from 63 scalp sites to a 250-ms vowel. Amplitude and latency of peaks were measured at left and right frontal sites (near Fz) and at left and right temporal sites (T7 and T8). In addition, the largest peak (typically corresponding to P1) was selected from global field power (GFP). The results revealed a large positive peak (P1) easily identified at frontal sites across all ages. The N2 emerged after 6 months of age and the following P2 between 8 and 30 months of age. The latencies of these peaks decreased exponentially with the most rapid decrease observed for P1. For amplitude, only P1 showed a clear relationship with age, becoming more positive in a somewhat linear fashion. At the temporal sites only a negative peak, which might be Na, was clearly observed at both left and right sites in children older than 14 months and peaking between 100 and 200 ms. P1 measures at frontal sites and Na peak latencies were moderately correlated. The temporal negative peak latency showed a different maturational timecourse (linear in nature) than the P1 peak, suggesting at least partial independence. Distinct Ta (positive) and Tb (negative) peaks, following Na and peaking between 120 and 220 ms were not consistently found in most age groups of children, except Ta which was present in 7 year olds. Future research, which includes manipulation of stimulus factors, and use of modeling techniques will be needed to explain the apparent, protracted maturation of the temporal site measures in the current study. PMID:25219893

  9. Spontaneous Decoding of the Timing and Content of Human Object Perception from Cortical Surface Recordings Reveals Complementary Information in the Event-Related Potential and Broadband Spectral Change

    PubMed Central

    Miller, Kai J.; Schalk, Gerwin; Hermes, Dora; Ojemann, Jeffrey G.; Rao, Rajesh P. N.

    2016-01-01

    The link between object perception and neural activity in visual cortical areas is a problem of fundamental importance in neuroscience. Here we show that electrical potentials from the ventral temporal cortical surface in humans contain sufficient information for spontaneous and near-instantaneous identification of a subject’s perceptual state. Electrocorticographic (ECoG) arrays were placed on the subtemporal cortical surface of seven epilepsy patients. Grayscale images of faces and houses were displayed rapidly in random sequence. We developed a template projection approach to decode the continuous ECoG data stream spontaneously, predicting the occurrence, timing and type of visual stimulus. In this setting, we evaluated the independent and joint use of two well-studied features of brain signals, broadband changes in the frequency power spectrum of the potential and deflections in the raw potential trace (event-related potential; ERP). Our ability to predict both the timing of stimulus onset and the type of image was best when we used a combination of both the broadband response and ERP, suggesting that they capture different and complementary aspects of the subject’s perceptual state. Specifically, we were able to predict the timing and type of 96% of all stimuli, with less than 5% false positive rate and a ~20ms error in timing. PMID:26820899

  10. Spontaneous Decoding of the Timing and Content of Human Object Perception from Cortical Surface Recordings Reveals Complementary Information in the Event-Related Potential and Broadband Spectral Change.

    PubMed

    Miller, Kai J; Schalk, Gerwin; Hermes, Dora; Ojemann, Jeffrey G; Rao, Rajesh P N

    2016-01-01

    The link between object perception and neural activity in visual cortical areas is a problem of fundamental importance in neuroscience. Here we show that electrical potentials from the ventral temporal cortical surface in humans contain sufficient information for spontaneous and near-instantaneous identification of a subject's perceptual state. Electrocorticographic (ECoG) arrays were placed on the subtemporal cortical surface of seven epilepsy patients. Grayscale images of faces and houses were displayed rapidly in random sequence. We developed a template projection approach to decode the continuous ECoG data stream spontaneously, predicting the occurrence, timing and type of visual stimulus. In this setting, we evaluated the independent and joint use of two well-studied features of brain signals, broadband changes in the frequency power spectrum of the potential and deflections in the raw potential trace (event-related potential; ERP). Our ability to predict both the timing of stimulus onset and the type of image was best when we used a combination of both the broadband response and ERP, suggesting that they capture different and complementary aspects of the subject's perceptual state. Specifically, we were able to predict the timing and type of 96% of all stimuli, with less than 5% false positive rate and a ~20ms error in timing. PMID:26820899

  11. Inhibitory Circuits in Cortical Layer 5

    PubMed Central

    Naka, Alexander; Adesnik, Hillel

    2016-01-01

    Inhibitory neurons play a fundamental role in cortical computation and behavior. Recent technological advances, such as two photon imaging, targeted in vivo recording, and molecular profiling, have improved our understanding of the function and diversity of cortical interneurons, but for technical reasons most work has been directed towards inhibitory neurons in the superficial cortical layers. Here we review current knowledge specifically on layer 5 (L5) inhibitory microcircuits, which play a critical role in controlling cortical output. We focus on recent work from the well-studied rodent barrel cortex, but also draw on evidence from studies in primary visual cortex and other cortical areas. The diversity of both deep inhibitory neurons and their pyramidal cell targets make this a challenging but essential area of study in cortical computation and sensory processing. PMID:27199675

  12. Inhibitory Circuits in Cortical Layer 5.

    PubMed

    Naka, Alexander; Adesnik, Hillel

    2016-01-01

    Inhibitory neurons play a fundamental role in cortical computation and behavior. Recent technological advances, such as two photon imaging, targeted in vivo recording, and molecular profiling, have improved our understanding of the function and diversity of cortical interneurons, but for technical reasons most work has been directed towards inhibitory neurons in the superficial cortical layers. Here we review current knowledge specifically on layer 5 (L5) inhibitory microcircuits, which play a critical role in controlling cortical output. We focus on recent work from the well-studied rodent barrel cortex, but also draw on evidence from studies in primary visual cortex and other cortical areas. The diversity of both deep inhibitory neurons and their pyramidal cell targets make this a challenging but essential area of study in cortical computation and sensory processing. PMID:27199675

  13. Size and weight graded multi-ply laminar electrodes

    DOEpatents

    Liu, Chia-Tsun; Demczyk, Brian G.; Rittko, Irvin R.

    1984-01-01

    An electrode is made comprising a porous backing sheet, and attached thereto a catalytically active layer having an electrolyte permeable side and a backing layer contacting side, where the active layer comprises a homogeneous mixture of active hydrophobic and hydrophilic agglomerates with catalyst disposed equally throughout the active layer, and where the agglomerate size increases from the electrolyte permeable side to the backing sheet contacting side.

  14. Mapping Cortical Responses to Somatosensory Stimuli in Human Infants with Simultaneous Near-Infrared Spectroscopy and Event-Related Potential Recording.

    PubMed

    Verriotis, Madeleine; Fabrizi, Lorenzo; Lee, Amy; Cooper, Robert J; Fitzgerald, Maria; Meek, Judith

    2016-01-01

    Near-infrared spectroscopy (NIRS) and electroencephalography (EEG) have recently provided fundamental new information about how the newborn brain processes innocuous and noxious somatosensory information. However, results derived independently from these two techniques are not entirely consistent, raising questions about the relationship between hemodynamic and electrophysiological responses in the study of touch and pain processing in the newborn. To address this, we have recorded NIRS and EEG responses simultaneously for the first time in the human infant following noxious (time-locked clinically required heel lances) and innocuous tactile cutaneous stimulation in 30 newborn infants. The results show that both techniques can be used to record quantifiable and distinct innocuous and noxious evoked activity at a group level in the newborn cortex. Noxious stimulation elicits a peak hemodynamic response that is 10-fold larger than that elicited by an innocuous stimulus (HbO2: 2.0 vs 0.3 µM) and a distinct nociceptive-specific N3P3 waveform in electrophysiological recordings. However, a novel single-trial analysis revealed that hemodynamic and electrophysiological responses do not always co-occur at an individual level, although when they do (64% of noxious test occasions), they are significantly correlated in magnitude. These data show that, while hemodynamic and electrophysiological touch and pain brain activity in newborn infants are comparable in group analyses, important individual differences remain. These data indicate that integrated and multimodal brain monitoring is required to understand central touch and pain processing in the newborn. PMID:27200413

  15. Mapping Cortical Responses to Somatosensory Stimuli in Human Infants with Simultaneous Near-Infrared Spectroscopy and Event-Related Potential Recording123

    PubMed Central

    Fabrizi, Lorenzo; Lee, Amy; Cooper, Robert J.; Fitzgerald, Maria; Meek, Judith

    2016-01-01

    Abstract Near-infrared spectroscopy (NIRS) and electroencephalography (EEG) have recently provided fundamental new information about how the newborn brain processes innocuous and noxious somatosensory information. However, results derived independently from these two techniques are not entirely consistent, raising questions about the relationship between hemodynamic and electrophysiological responses in the study of touch and pain processing in the newborn. To address this, we have recorded NIRS and EEG responses simultaneously for the first time in the human infant following noxious (time-locked clinically required heel lances) and innocuous tactile cutaneous stimulation in 30 newborn infants. The results show that both techniques can be used to record quantifiable and distinct innocuous and noxious evoked activity at a group level in the newborn cortex. Noxious stimulation elicits a peak hemodynamic response that is 10-fold larger than that elicited by an innocuous stimulus (HbO2: 2.0 vs 0.3 µm) and a distinct nociceptive-specific N3P3 waveform in electrophysiological recordings. However, a novel single-trial analysis revealed that hemodynamic and electrophysiological responses do not always co-occur at an individual level, although when they do (64% of noxious test occasions), they are significantly correlated in magnitude. These data show that, while hemodynamic and electrophysiological touch and pain brain activity in newborn infants are comparable in group analyses, important individual differences remain. These data indicate that integrated and multimodal brain monitoring is required to understand central touch and pain processing in the newborn. PMID:27200413

  16. Encoding Cortical Dynamics in Sparse Features

    PubMed Central

    Khan, Sheraz; Lefèvre, Julien; Baillet, Sylvain; Michmizos, Konstantinos P.; Ganesan, Santosh; Kitzbichler, Manfred G.; Zetino, Manuel; Hämäläinen, Matti S.; Papadelis, Christos; Kenet, Tal

    2014-01-01

    Distributed cortical solutions of magnetoencephalography (MEG) and electroencephalography (EEG) exhibit complex spatial and temporal dynamics. The extraction of patterns of interest and dynamic features from these cortical signals has so far relied on the expertise of investigators. There is a definite need in both clinical and neuroscience research for a method that will extract critical features from high-dimensional neuroimaging data in an automatic fashion. We have previously demonstrated the use of optical flow techniques for evaluating the kinematic properties of motion field projected on non-flat manifolds like in a cortical surface. We have further extended this framework to automatically detect features in the optical flow vector field by using the modified and extended 2-Riemannian Helmholtz–Hodge decomposition (HHD). Here, we applied these mathematical models on simulation and MEG data recorded from a healthy individual during a somatosensory experiment and an epilepsy pediatric patient during sleep. We tested whether our technique can automatically extract salient dynamical features of cortical activity. Simulation results indicated that we can precisely reproduce the simulated cortical dynamics with HHD; encode them in sparse features and represent the propagation of brain activity between distinct cortical areas. Using HHD, we decoded the somatosensory N20 component into two HHD features and represented the dynamics of brain activity as a traveling source between two primary somatosensory regions. In the epilepsy patient, we displayed the propagation of the epileptic activity around the margins of a brain lesion. Our findings indicate that HHD measures computed from cortical dynamics can: (i) quantitatively access the cortical dynamics in both healthy and disease brain in terms of sparse features and dynamic brain activity propagation between distinct cortical areas, and (ii) facilitate a reproducible, automated analysis of experimental and clinical

  17. Encoding cortical dynamics in sparse features.

    PubMed

    Khan, Sheraz; Lefèvre, Julien; Baillet, Sylvain; Michmizos, Konstantinos P; Ganesan, Santosh; Kitzbichler, Manfred G; Zetino, Manuel; Hämäläinen, Matti S; Papadelis, Christos; Kenet, Tal

    2014-01-01

    Distributed cortical solutions of magnetoencephalography (MEG) and electroencephalography (EEG) exhibit complex spatial and temporal dynamics. The extraction of patterns of interest and dynamic features from these cortical signals has so far relied on the expertise of investigators. There is a definite need in both clinical and neuroscience research for a method that will extract critical features from high-dimensional neuroimaging data in an automatic fashion. We have previously demonstrated the use of optical flow techniques for evaluating the kinematic properties of motion field projected on non-flat manifolds like in a cortical surface. We have further extended this framework to automatically detect features in the optical flow vector field by using the modified and extended 2-Riemannian Helmholtz-Hodge decomposition (HHD). Here, we applied these mathematical models on simulation and MEG data recorded from a healthy individual during a somatosensory experiment and an epilepsy pediatric patient during sleep. We tested whether our technique can automatically extract salient dynamical features of cortical activity. Simulation results indicated that we can precisely reproduce the simulated cortical dynamics with HHD; encode them in sparse features and represent the propagation of brain activity between distinct cortical areas. Using HHD, we decoded the somatosensory N20 component into two HHD features and represented the dynamics of brain activity as a traveling source between two primary somatosensory regions. In the epilepsy patient, we displayed the propagation of the epileptic activity around the margins of a brain lesion. Our findings indicate that HHD measures computed from cortical dynamics can: (i) quantitatively access the cortical dynamics in both healthy and disease brain in terms of sparse features and dynamic brain activity propagation between distinct cortical areas, and (ii) facilitate a reproducible, automated analysis of experimental and clinical

  18. Cortical Control of Affective Networks

    PubMed Central

    Kumar, Sunil; Black, Sherilynn J.; Hultman, Rainbo; Szabo, Steven T.; DeMaio, Kristine D.; Du, Jeanette; Katz, Brittany M.; Feng, Guoping; Covington, Herbert E.; Dzirasa, Kafui

    2013-01-01

    Transcranial magnetic stimulation and deep brain stimulation have emerged as therapeutic modalities for treatment refractory depression; however, little remains known regarding the circuitry that mediates the therapeutic effect of these approaches. Here we show that direct optogenetic stimulation of prefrontal cortex (PFC) descending projection neurons in mice engineered to express Chr2 in layer V pyramidal neurons (Thy1–Chr2 mice) models an antidepressant-like effect in mice subjected to a forced-swim test. Furthermore, we show that this PFC stimulation induces a long-lasting suppression of anxiety-like behavior (but not conditioned social avoidance) in socially stressed Thy1–Chr2 mice: an effect that is observed >10 d after the last stimulation. Finally, we use optogenetic stimulation and multicircuit recording techniques concurrently in Thy1–Chr2 mice to demonstrate that activation of cortical projection neurons entrains neural oscillatory activity and drives synchrony across limbic brain areas that regulate affect. Importantly, these neural oscillatory changes directly correlate with the temporally precise activation and suppression of limbic unit activity. Together, our findings show that the direct activation of cortical projection systems is sufficient to modulate activity across networks underlying affective regulation. They also suggest that optogenetic stimulation of cortical projection systems may serve as a viable therapeutic strategy for treating affective disorders. PMID:23325249

  19. 21 CFR 882.1310 - Cortical electrode.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...) Identification. A cortical electrode is an electrode which is temporarily placed on the surface of the brain for stimulating the brain or recording the brain's electrical activity. (b) Classification. Class II...

  20. 21 CFR 882.1310 - Cortical electrode.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...) Identification. A cortical electrode is an electrode which is temporarily placed on the surface of the brain for stimulating the brain or recording the brain's electrical activity. (b) Classification. Class II...

  1. 21 CFR 882.1310 - Cortical electrode.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...) Identification. A cortical electrode is an electrode which is temporarily placed on the surface of the brain for stimulating the brain or recording the brain's electrical activity. (b) Classification. Class II...

  2. 21 CFR 882.1310 - Cortical electrode.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...) Identification. A cortical electrode is an electrode which is temporarily placed on the surface of the brain for stimulating the brain or recording the brain's electrical activity. (b) Classification. Class II...

  3. 21 CFR 882.1310 - Cortical electrode.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...) Identification. A cortical electrode is an electrode which is temporarily placed on the surface of the brain for stimulating the brain or recording the brain's electrical activity. (b) Classification. Class II...

  4. Pharmacology of cortical inhibition

    PubMed Central

    Krnjević, K.; Randić, Mirjana; Straughan, D. W.

    1966-01-01

    1. We have studied the effects of various pharmacological agents on the cortical inhibitory process described in the previous two papers (Krnjević, Randić & Straughan, 1966a, b); the drugs were mostly administered directly by iontophoresis from micropipettes and by systemic injection (I.V.). 2. Strychnine given by iontophoresis or by the application of a strong solution to the cortical surface potentiated excitatory effects, but very large iontophoretic doses also depressed neuronal firing. Subconvulsive and even convulsive systemic doses had little or no effect at the cortical level. There was no evidence, with any method of application, that strychnine directly interferes with the inhibitory process. 3. Tetanus toxin, obtained from two different sources and injected into the cortex 12-48 hr previously, also failed to block cortical inhibition selectively. As with strychnine, there was some evidence of increased responses to excitatory inputs. 4. Other convulsant drugs which failed to block cortical inhibition included picrotoxin, pentamethylene tetrazole, thiosemicarbazide, longchain ω-amino acids and morphine. 5. The inhibition was not obviously affected by cholinomimetic agents or by antagonists of ACh. 6. α- and β-antagonists of adrenergic transmission were also ineffective. 7. Cortical inhibition was fully developed in the presence of several general anaesthetics, including ether, Dial, pentobarbitone, Mg and chloralose. A temporary reduction in inhibition which is sometimes observed after systemic doses of pentobarbitone, is probably secondary to a fall in blood pressure. 8. Several central excitants such as amphetamine, caffeine and lobeline also failed to show any specific antagonistic action on cortical inhibition. 9. In view of the possibility that GABA is the chemical agent mediating cortical inhibition, an attempt was made to find a selective antagonist of its depressant action on cortical neurones. None of the agents listed above, nor any other

  5. Behavioral Dependence of Auditory Cortical Responses

    PubMed Central

    Osmanski, Michael S.; Wang, Xiaoqin

    2015-01-01

    Neural responses in the auditory cortex have historically been measured from either anesthetized or awake but non-behaving animals. A growing body of work has begun to focus instead on recording from auditory cortex of animals actively engaged in behavior tasks. These studies have shown that auditory cortical responses are dependent upon the behavioral state of the animal. The longer ascending subcortical pathway of the auditory system and unique characteristics of auditory processing suggest that such dependencies may have a more profound influence on cortical processing in auditory system compared to other sensory systems. It is important to understand the nature of these dependencies and their functional implications. In this article, we review the literature on this topic pertaining to cortical processing of sounds. PMID:25690831

  6. Cortical State and Attention

    PubMed Central

    Harris, Kenneth D.; Thiele, Alexander

    2012-01-01

    Preface The brain continuously adapts its processing machinery to behavioural demands. To achieve this it rapidly modulates the operating mode of cortical circuits, controlling the way information is transformed and routed. This article will focus on two experimental approaches by which the control of cortical information processing has been investigated: the study of state-dependent cortical processing in rodents, and attention in the primate visual system. Both processes involve a modulation of low-frequency activity fluctuations and spiking correlation, and are mediated by common receptor systems. We suggest that selective attention involves processes similar to state change, operating at a local columnar level to enhance the representation of otherwise nonsalient features while suppressing internally generated activity patterns. PMID:21829219

  7. Cortical dynamics revisited.

    PubMed

    Singer, Wolf

    2013-12-01

    Recent discoveries on the organisation of the cortical connectome together with novel data on the dynamics of neuronal interactions require an extension of classical concepts on information processing in the cerebral cortex. These new insights justify considering the brain as a complex, self-organised system with nonlinear dynamics in which principles of distributed, parallel processing coexist with serial operations within highly interconnected networks. The observed dynamics suggest that cortical networks are capable of providing an extremely high-dimensional state space in which a large amount of evolutionary and ontogenetically acquired information can coexist and be accessible to rapid parallel search. PMID:24139950

  8. Cortical organization in shrews: evidence from five species.

    PubMed

    Catania, K C; Lyon, D C; Mock, O B; Kaas, J H

    1999-07-19

    Cortical organization was examined in five shrew species. In three species, Blarina brevicauda, Cryptotis parva, and Sorex palustris, microelectrode recordings were made in cortex to determine the organization of sensory areas. Cortical recordings were then related to flattened sections of cortex processed for cytochrome oxidase or myelin to reveal architectural borders. An additional two species (Sorex cinereus and Sorex longirostris) with visible cortical subdivisions based on histology alone were analyzed without electrophysiological mapping. A single basic plan of cortical organization was found in shrews, consisting of a few clearly defined sensory areas located caudally in cortex. Two somatosensory areas contained complete representations of the contralateral body, corresponding to primary somatosensory cortex (S1) and secondary somatosensory cortex (S2). A small primary visual cortex (V1) was located closely adjacent to S1, whereas auditory cortex (A1) was located in extreme caudolateral cortex, partially encircled by S2. Areas did not overlap and had sharp, histochemically apparent and electrophysiologically defined borders. The adjacency of these areas suggests a complete absence of intervening higher level or association areas. Based on a previous study of corticospinal connections, a presumptive primary motor cortex (M1) was identified directly rostral to S1. Apparently, in shrews, the solution to having extremely little neocortex is to have only a few small cortical subdivisions. However, the small areas remain discrete, well organized, and functional. This cortical organization in shrews is likely a derived condition, because a wide range of extant mammals have a greater number of cortical subdivisions. PMID:10397395

  9. Cortical thinning in psychopathy

    PubMed Central

    Ly, Martina; Motzkin, Julian C.; Philippi, Carissa L.; Kirk, Gregory R.; Newman, Joseph P.; Kiehl, Kent A.; Koenigs, Michael

    2013-01-01

    Objective Psychopathy is a personality disorder associated with severely antisocial behavior and a host of cognitive and affective deficits. The neuropathological basis of the disorder has not been clearly established. Cortical thickness is a sensitive measure of brain structure that has been used to identify neurobiological abnormalities in a number of psychiatric disorders. The purpose of this study is to evaluate cortical thickness and corresponding functional connectivity in criminal psychopaths. Method Using T1 MRI data, we computed cortical thickness maps in a sample of adult male prison inmates selected based on psychopathy diagnosis (n=21 psychopathic inmates, n=31 non-psychopathic inmates). Using rest-fMRI data from a subset of these inmates (n=20 psychopathic inmates, n=20 non-psychopathic inmates), we then computed functional connectivity within networks exhibiting significant thinning among psychopaths. Results Relative to non-psychopaths, psychopaths exhibited significantly thinner cortex in a number of regions, including left insula and dorsal anterior cingulate cortex, bilateral precentral gyrus, bilateral anterior temporal cortex, and right inferior frontal gyrus. These neurostructural differences were not due to differences in age, IQ, or substance abuse. Psychopaths also exhibited a corresponding reduction in functional connectivity between left insula and left dorsal anterior cingulate cortex. Conclusions Psychopathy is associated with a distinct pattern of cortical thinning and reduced functional connectivity. PMID:22581200

  10. Touch inhibits subcortical and cortical nociceptive responses

    PubMed Central

    Mancini, Flavia; Beaumont, Anne-Lise; Hu, Li; Haggard, Patrick; Iannetti, Gian Domenico D.

    2015-01-01

    Abstract The neural mechanisms of the powerful analgesia induced by touching a painful body part are controversial. A long tradition of neurophysiologic studies in anaesthetized spinal animals indicate that touch can gate nociceptive input at spinal level. In contrast, recent studies in awake humans have suggested that supraspinal mechanisms can be sufficient to drive touch-induced analgesia. To investigate this issue, we evaluated the modulation exerted by touch on established electrophysiologic markers of nociceptive function at both subcortical and cortical levels in humans. Aδ and C skin nociceptors were selectively activated by high-power laser pulses. As markers of subcortical and cortical function, we recorded the laser blink reflex, which is generated by brainstem circuits before the arrival of nociceptive signals at the cortex, and laser-evoked potentials, which reflect neural activity of a wide array of cortical areas. If subcortical nociceptive responses are inhibited by concomitant touch, supraspinal mechanisms alone are unlikely to be sufficient to drive touch-induced analgesia. Touch induced a clear analgesic effect, suppressed the laser blink reflex, and inhibited both Aδ-fibre and C-fibre laser-evoked potentials. Thus, we conclude that touch-induced analgesia is likely to be mediated by a subcortical gating of the ascending nociceptive input, which in turn results in a modulation of cortical responses. Hence, supraspinal mechanisms alone are not sufficient to mediate touch-induced analgesia. PMID:26058037

  11. Touch inhibits subcortical and cortical nociceptive responses.

    PubMed

    Mancini, Flavia; Beaumont, Anne-Lise; Hu, Li; Haggard, Patrick; Iannetti, Giandomenico D; Iannetti, Gian Domenico D

    2015-10-01

    The neural mechanisms of the powerful analgesia induced by touching a painful body part are controversial. A long tradition of neurophysiologic studies in anaesthetized spinal animals indicate that touch can gate nociceptive input at spinal level. In contrast, recent studies in awake humans have suggested that supraspinal mechanisms can be sufficient to drive touch-induced analgesia. To investigate this issue, we evaluated the modulation exerted by touch on established electrophysiologic markers of nociceptive function at both subcortical and cortical levels in humans. Aδ and C skin nociceptors were selectively activated by high-power laser pulses. As markers of subcortical and cortical function, we recorded the laser blink reflex, which is generated by brainstem circuits before the arrival of nociceptive signals at the cortex, and laser-evoked potentials, which reflect neural activity of a wide array of cortical areas. If subcortical nociceptive responses are inhibited by concomitant touch, supraspinal mechanisms alone are unlikely to be sufficient to drive touch-induced analgesia. Touch induced a clear analgesic effect, suppressed the laser blink reflex, and inhibited both Aδ-fibre and C-fibre laser-evoked potentials. Thus, we conclude that touch-induced analgesia is likely to be mediated by a subcortical gating of the ascending nociceptive input, which in turn results in a modulation of cortical responses. Hence, supraspinal mechanisms alone are not sufficient to mediate touch-induced analgesia. PMID:26058037

  12. Modulation of Cortical Oscillations by Low-Frequency Direct Cortical Stimulation Is State-Dependent

    PubMed Central

    Alagapan, Sankaraleengam; Schmidt, Stephen L.; Lefebvre, Jérémie; Hadar, Eldad; Shin, Hae Won; Frӧhlich, Flavio

    2016-01-01

    Cortical oscillations play a fundamental role in organizing large-scale functional brain networks. Noninvasive brain stimulation with temporally patterned waveforms such as repetitive transcranial magnetic stimulation (rTMS) and transcranial alternating current stimulation (tACS) have been proposed to modulate these oscillations. Thus, these stimulation modalities represent promising new approaches for the treatment of psychiatric illnesses in which these oscillations are impaired. However, the mechanism by which periodic brain stimulation alters endogenous oscillation dynamics is debated and appears to depend on brain state. Here, we demonstrate with a static model and a neural oscillator model that recurrent excitation in the thalamo-cortical circuit, together with recruitment of cortico-cortical connections, can explain the enhancement of oscillations by brain stimulation as a function of brain state. We then performed concurrent invasive recording and stimulation of the human cortical surface to elucidate the response of cortical oscillations to periodic stimulation and support the findings from the computational models. We found that (1) stimulation enhanced the targeted oscillation power, (2) this enhancement outlasted stimulation, and (3) the effect of stimulation depended on behavioral state. Together, our results show successful target engagement of oscillations by periodic brain stimulation and highlight the role of nonlinear interaction between endogenous network oscillations and stimulation. These mechanistic insights will contribute to the design of adaptive, more targeted stimulation paradigms. PMID:27023427

  13. Modulation of Cortical Oscillations by Low-Frequency Direct Cortical Stimulation Is State-Dependent.

    PubMed

    Alagapan, Sankaraleengam; Schmidt, Stephen L; Lefebvre, Jérémie; Hadar, Eldad; Shin, Hae Won; Frӧhlich, Flavio

    2016-03-01

    Cortical oscillations play a fundamental role in organizing large-scale functional brain networks. Noninvasive brain stimulation with temporally patterned waveforms such as repetitive transcranial magnetic stimulation (rTMS) and transcranial alternating current stimulation (tACS) have been proposed to modulate these oscillations. Thus, these stimulation modalities represent promising new approaches for the treatment of psychiatric illnesses in which these oscillations are impaired. However, the mechanism by which periodic brain stimulation alters endogenous oscillation dynamics is debated and appears to depend on brain state. Here, we demonstrate with a static model and a neural oscillator model that recurrent excitation in the thalamo-cortical circuit, together with recruitment of cortico-cortical connections, can explain the enhancement of oscillations by brain stimulation as a function of brain state. We then performed concurrent invasive recording and stimulation of the human cortical surface to elucidate the response of cortical oscillations to periodic stimulation and support the findings from the computational models. We found that (1) stimulation enhanced the targeted oscillation power, (2) this enhancement outlasted stimulation, and (3) the effect of stimulation depended on behavioral state. Together, our results show successful target engagement of oscillations by periodic brain stimulation and highlight the role of nonlinear interaction between endogenous network oscillations and stimulation. These mechanistic insights will contribute to the design of adaptive, more targeted stimulation paradigms. PMID:27023427

  14. Posterior Cortical Atrophy

    PubMed Central

    Crutch, Sebastian J; Lehmann, Manja; Schott, Jonathan M; Rabinovici, Gil D; Rossor, Martin N; Fox, Nick C

    2013-01-01

    Posterior cortical atrophy (PCA) is a neurodegenerative syndrome that is characterized by a progressive decline in visuospatial, visuoperceptual, literacy and praxic skills. The progressive neurodegeneration affecting parietal, occipital and occipito-temporal cortices which underlies PCA is attributable to Alzheimer's disease (AD) in the majority of patients. However, alternative underlying aetiologies including Dementia with Lewy Bodies (DLB), corticobasal degeneration (CBD) and prion disease have also been identified, and not all PCA patients have atrophy on clinical imaging. This heterogeneity has led to diagnostic and terminological inconsistencies, caused difficulty comparing studies from different centres, and limited the generalizability of clinical trials and investigations of factors driving phenotypic variability. Significant challenges remain in identifying the factors associated with both the selective vulnerability of posterior cortical regions and the young age of onset seen in PCA. Greater awareness of the syndrome and agreement over the correspondence between syndrome-and disease-level classifications are required in order to improve diagnostic accuracy, research study design and clinical management. PMID:22265212

  15. Malformations of cortical development

    PubMed Central

    Pang, Trudy; Atefy, Ramin; Sheen, Volney

    2012-01-01

    Background Malformations of cortical development (MCD) are increasingly recognized as an important cause of epilepsy and developmental delay. MCD encompass a wide spectrum of disorders with various underlying genetic etiologies and clinical manifestations. High resolution imaging has dramatically improved our recognition of MCD. Review Summary This review will provide a brief overview of the stages of normal cortical development, including neuronal proliferation, neuroblast migration, and neuronal organization. Disruptions at various stages lead to characteristic MCD. Disorders of neurogenesis give rise to microcephaly (small brain) or macrocephaly (large brain). Disorders of early neuroblast migration give rise to periventricular heterotopia (neurons located along the ventricles), whereas abnormalities later in migration lead to lissencephaly (smooth brain) or subcortical band heterotopia (smooth brain with a band of heterotopic neurons under the cortex). Abnormal neuronal migration arrest give rise to over-migration of neurons in cobblestone lissencephaly. Lastly, disorders of neuronal organization cause polymicrogyria (abnormally small gyri and sulci). This review will also discuss the known genetic mutations and potential mechanisms that contribute to these syndromes. Conclusion Identification of various gene mutations has not only given us greater insight into some of the pathophysiologic basis of MCD, but also an understanding of the processes involved in normal cortical development. PMID:18469675

  16. Dynamics of Ionic Shifts in Cortical Spreading Depression.

    PubMed

    Enger, Rune; Tang, Wannan; Vindedal, Gry Fluge; Jensen, Vidar; Johannes Helm, P; Sprengel, Rolf; Looger, Loren L; Nagelhus, Erlend A

    2015-11-01

    Cortical spreading depression is a slowly propagating wave of near-complete depolarization of brain cells followed by temporary suppression of neuronal activity. Accumulating evidence indicates that cortical spreading depression underlies the migraine aura and that similar waves promote tissue damage in stroke, trauma, and hemorrhage. Cortical spreading depression is characterized by neuronal swelling, profound elevation of extracellular potassium and glutamate, multiphasic blood flow changes, and drop in tissue oxygen tension. The slow speed of the cortical spreading depression wave implies that it is mediated by diffusion of a chemical substance, yet the identity of this substance and the pathway it follows are unknown. Intercellular spread between gap junction-coupled neurons or glial cells and interstitial diffusion of K(+) or glutamate have been proposed. Here we use extracellular direct current potential recordings, K(+)-sensitive microelectrodes, and 2-photon imaging with ultrasensitive Ca(2+) and glutamate fluorescent probes to elucidate the spatiotemporal dynamics of ionic shifts associated with the propagation of cortical spreading depression in the visual cortex of adult living mice. Our data argue against intercellular spread of Ca(2+) carrying the cortical spreading depression wavefront and are in favor of interstitial K(+) diffusion, rather than glutamate diffusion, as the leading event in cortical spreading depression. PMID:25840424

  17. Early development of synchrony in cortical activations in the human

    PubMed Central

    Koolen, N.; Dereymaeker, A.; Räsänen, O.; Jansen, K.; Vervisch, J.; Matic, V.; Naulaers, G.; De Vos, M.; Van Huffel, S.; Vanhatalo, S.

    2016-01-01

    Early intermittent cortical activity is thought to play a crucial role in the growth of neuronal network development, and large scale brain networks are known to provide the basis for higher brain functions. Yet, the early development of the large scale synchrony in cortical activations is unknown. Here, we tested the hypothesis that the early intermittent cortical activations seen in the human scalp EEG show a clear developmental course during the last trimester of pregnancy, the period of intensive growth of cortico-cortical connections. We recorded scalp EEG from altogether 22 premature infants at post-menstrual age between 30 and 44 weeks, and the early cortical synchrony was quantified using recently introduced activation synchrony index (ASI). The developmental correlations of ASI were computed for individual EEG signals as well as anatomically and mathematically defined spatial subgroups. We report two main findings. First, we observed a robust and statistically significant increase in ASI in all cortical areas. Second, there were significant spatial gradients in the synchrony in fronto-occipital and left-to-right directions. These findings provide evidence that early cortical activity is increasingly synchronized across the neocortex. The ASI-based metrics introduced in our work allow direct translational comparison to in vivo animal models, as well as hold promise for implementation as a functional developmental biomarker in future research on human neonates. PMID:26876605

  18. Early development of synchrony in cortical activations in the human.

    PubMed

    Koolen, N; Dereymaeker, A; Räsänen, O; Jansen, K; Vervisch, J; Matic, V; Naulaers, G; De Vos, M; Van Huffel, S; Vanhatalo, S

    2016-05-13

    Early intermittent cortical activity is thought to play a crucial role in the growth of neuronal network development, and large scale brain networks are known to provide the basis for higher brain functions. Yet, the early development of the large scale synchrony in cortical activations is unknown. Here, we tested the hypothesis that the early intermittent cortical activations seen in the human scalp EEG show a clear developmental course during the last trimester of pregnancy, the period of intensive growth of cortico-cortical connections. We recorded scalp EEG from altogether 22 premature infants at post-menstrual age between 30 and 44weeks, and the early cortical synchrony was quantified using recently introduced activation synchrony index (ASI). The developmental correlations of ASI were computed for individual EEG signals as well as anatomically and mathematically defined spatial subgroups. We report two main findings. First, we observed a robust and statistically significant increase in ASI in all cortical areas. Second, there were significant spatial gradients in the synchrony in fronto-occipital and left-to-right directions. These findings provide evidence that early cortical activity is increasingly synchronized across the neocortex. The ASI-based metrics introduced in our work allow direct translational comparison to in vivo animal models, as well as hold promise for implementation as a functional developmental biomarker in future research on human neonates. PMID:26876605

  19. Dynamics of Ionic Shifts in Cortical Spreading Depression

    PubMed Central

    Enger, Rune; Tang, Wannan; Vindedal, Gry Fluge; Jensen, Vidar; Johannes Helm, P.; Sprengel, Rolf; Looger, Loren L.; Nagelhus, Erlend A.

    2015-01-01

    Cortical spreading depression is a slowly propagating wave of near-complete depolarization of brain cells followed by temporary suppression of neuronal activity. Accumulating evidence indicates that cortical spreading depression underlies the migraine aura and that similar waves promote tissue damage in stroke, trauma, and hemorrhage. Cortical spreading depression is characterized by neuronal swelling, profound elevation of extracellular potassium and glutamate, multiphasic blood flow changes, and drop in tissue oxygen tension. The slow speed of the cortical spreading depression wave implies that it is mediated by diffusion of a chemical substance, yet the identity of this substance and the pathway it follows are unknown. Intercellular spread between gap junction-coupled neurons or glial cells and interstitial diffusion of K+ or glutamate have been proposed. Here we use extracellular direct current potential recordings, K+-sensitive microelectrodes, and 2-photon imaging with ultrasensitive Ca2+ and glutamate fluorescent probes to elucidate the spatiotemporal dynamics of ionic shifts associated with the propagation of cortical spreading depression in the visual cortex of adult living mice. Our data argue against intercellular spread of Ca2+ carrying the cortical spreading depression wavefront and are in favor of interstitial K+ diffusion, rather than glutamate diffusion, as the leading event in cortical spreading depression. PMID:25840424

  20. Synaptic strength modulation after cortical trauma: a role in epileptogenesis.

    PubMed

    Avramescu, Sinziana; Timofeev, Igor

    2008-07-01

    Traumatic brain injuries are often followed by abnormal hyperexcitability, leading to acute seizures and epilepsy. Previous studies documented the rewiring capacity of neocortical neurons in response to various cortical and subcortical lesions. However, little information is available on the functional consequences of these anatomical changes after cortical trauma and the adaptation of synaptic connectivity to a decreased input produced by chronic deafferentation. In this study, we recorded intracellular (IC) activities of cortical neurons simultaneously with extracellular (EC) unit activities and field potentials of neighboring cells in cat cortex, after a large transection of the white matter underneath the suprasylvian gyrus, in acute and chronic conditions (at 2, 4, and 6 weeks) in ketamine-xylazine-anesthetized cats. Using EC spikes to compute the spike-triggered averages of IC membrane potential, we found an increased connection probability and efficacy between cortical neurons weeks after cortical trauma. Inhibitory interactions showed no significant changes in the traumatized cortex compared with control. The increased synaptic efficacy was accompanied by enhanced input resistance and intrinsic excitability of cortical neurons, as well as by increased duration of silent network periods. Our electrophysiological data revealed functional consequences of previously reported anatomical changes in the injured cortex. We suggest that homeostatic synaptic plasticity compensating the decreased activity in the undercut cortex leads to an uncontrollable cortical hyperexcitability and seizure generation. PMID:18596152

  1. Cortical entrainment to music and its modulation by expertise

    PubMed Central

    Doelling, Keith B.; Poeppel, David

    2015-01-01

    Recent studies establish that cortical oscillations track naturalistic speech in a remarkably faithful way. Here, we test whether such neural activity, particularly low-frequency (<8 Hz; delta–theta) oscillations, similarly entrain to music and whether experience modifies such a cortical phenomenon. Music of varying tempi was used to test entrainment at different rates. In three magnetoencephalography experiments, we recorded from nonmusicians, as well as musicians with varying years of experience. Recordings from nonmusicians demonstrate cortical entrainment that tracks musical stimuli over a typical range of tempi, but not at tempi below 1 note per second. Importantly, the observed entrainment correlates with performance on a concurrent pitch-related behavioral task. In contrast, the data from musicians show that entrainment is enhanced by years of musical training, at all presented tempi. This suggests a bidirectional relationship between behavior and cortical entrainment, a phenomenon that has not previously been reported. Additional analyses focus on responses in the beta range (∼15–30 Hz)—often linked to delta activity in the context of temporal predictions. Our findings provide evidence that the role of beta in temporal predictions scales to the complex hierarchical rhythms in natural music and enhances processing of musical content. This study builds on important findings on brainstem plasticity and represents a compelling demonstration that cortical neural entrainment is tightly coupled to both musical training and task performance, further supporting a role for cortical oscillatory activity in music perception and cognition. PMID:26504238

  2. Cortical entrainment to music and its modulation by expertise.

    PubMed

    Doelling, Keith B; Poeppel, David

    2015-11-10

    Recent studies establish that cortical oscillations track naturalistic speech in a remarkably faithful way. Here, we test whether such neural activity, particularly low-frequency (<8 Hz; delta-theta) oscillations, similarly entrain to music and whether experience modifies such a cortical phenomenon. Music of varying tempi was used to test entrainment at different rates. In three magnetoencephalography experiments, we recorded from nonmusicians, as well as musicians with varying years of experience. Recordings from nonmusicians demonstrate cortical entrainment that tracks musical stimuli over a typical range of tempi, but not at tempi below 1 note per second. Importantly, the observed entrainment correlates with performance on a concurrent pitch-related behavioral task. In contrast, the data from musicians show that entrainment is enhanced by years of musical training, at all presented tempi. This suggests a bidirectional relationship between behavior and cortical entrainment, a phenomenon that has not previously been reported. Additional analyses focus on responses in the beta range (∼15-30 Hz)-often linked to delta activity in the context of temporal predictions. Our findings provide evidence that the role of beta in temporal predictions scales to the complex hierarchical rhythms in natural music and enhances processing of musical content. This study builds on important findings on brainstem plasticity and represents a compelling demonstration that cortical neural entrainment is tightly coupled to both musical training and task performance, further supporting a role for cortical oscillatory activity in music perception and cognition. PMID:26504238

  3. Cortical reorganization in children with cochlear implants.

    PubMed

    Gilley, Phillip M; Sharma, Anu; Dorman, Michael F

    2008-11-01

    Congenital deafness leads to atypical organization of the auditory nervous system. However, the extent to which auditory pathways reorganize during deafness is not well understood. We recorded cortical auditory evoked potentials in normal hearing children and in congenitally deaf children fitted with cochlear implants. High-density EEG and source modeling revealed principal activity from auditory cortex in normal hearing and early implanted children. However, children implanted after a critical period of seven years revealed activity from parietotemporal cortex in response to auditory stimulation, demonstrating reorganized cortical pathways. Reorganization of central auditory pathways is limited by the age at which implantation occurs, and may help explain the benefits and limitations of implantation in congenitally deaf children. PMID:18775684

  4. Optimizing sound features for cortical neurons.

    PubMed

    deCharms, R C; Blake, D T; Merzenich, M M

    1998-05-29

    The brain's cerebral cortex decomposes visual images into information about oriented edges, direction and velocity information, and color. How does the cortex decompose perceived sounds? A reverse correlation technique demonstrates that neurons in the primary auditory cortex of the awake primate have complex patterns of sound-feature selectivity that indicate sensitivity to stimulus edges in frequency or in time, stimulus transitions in frequency or intensity, and feature conjunctions. This allows the creation of classes of stimuli matched to the processing characteristics of auditory cortical neurons. Stimuli designed for a particular neuron's preferred feature pattern can drive that neuron with higher sustained firing rates than have typically been recorded with simple stimuli. These data suggest that the cortex decomposes an auditory scene into component parts using a feature-processing system reminiscent of that used for the cortical decomposition of visual images. PMID:9603734

  5. Cortical Clefts and Cortical Bumps: A Continuous Spectrum

    PubMed Central

    Furruqh, Farha; Thirunavukarasu, Suresh; Vivekandan, Ravichandran

    2016-01-01

    Cortical ‘clefts’ (schizencephaly) and cortical ‘bumps’ (polymicrogyria) are malformations arising due to defects in postmigrational development of neurons. They are frequently encountered together, with schizencephalic clefts being lined by polymicrogyria. We present the case of an eight-year-old boy who presented with seizures. Imaging revealed closed lip schizencephaly, polymicrogyria and a deep ‘incomplete’ cleft lined by polymicrogyria not communicating with the lateral ventricle. We speculate that hypoperfusion or ischaemic cortical injury during neuronal development may lead to a spectrum of malformations ranging from polymicrogyria to incomplete cortical clefts to schizencephaly.

  6. Motor cortical excitability and inhibition in acquired mirror pain.

    PubMed

    Fitzgibbon, Bernadette M; Enticott, Peter G; Bradshaw, John L; Giummarra, Melita J; Georgiou-Karistianis, Nellie; Chou, Michael; Fitzgerald, Paul B

    2012-11-21

    'Mirror pain' describes when the observation of another's pain experience induces a personal experience of pain. It has been suggested that mirror pain could result from changes in neural excitability or inhibition. In this study we used transcranial magnetic stimulation (TMS) to investigate motor cortical excitability in lower-limb amputees who experience mirror pain. Using paired-pulse TMS to assess motor cortical inhibition (CI) and cortical facilitation (CF), recordings were taken from the right first dorsal interosseus in lower-limb amputees who experience mirror pain (MP+), lower-limb amputees who do not experience mirror pain (MP-), and non-amputee controls. No differences in CI or CF were observed between the MP+ and both control groups. Thus, when not paired with a pain-related stimulus, changes in motor cortical excitability do not appear to contribute to the experience of mirror pain in lower-limb amputees. PMID:23022471

  7. Cortical basal ganglionic degeneration.

    PubMed

    Scarmeas, N; Chin, S S; Marder, K

    2001-10-01

    In this case study, we describe the symptoms, neuropsychological testing, and brain pathology of a retired mason's assistant with cortical basal ganglionic degeneration (CBGD). CBGD is an extremely rare neurodegenerative disease that is categorized under both Parkinsonian syndromes and frontal lobe dementias. It affects men and women nearly equally, and the age of onset is usually in the sixth decade of life. CBGD is characterized by Parkinson's-like motor symptoms and by deficits of movement and cognition, indicating focal brain pathology. Neuronal cell loss is ultimately responsible for the neurological symptoms. PMID:14602941

  8. Time in Cortical Circuits

    PubMed Central

    Shadlen, Michael N.; Jazayeri, Mehrdad; Nobre, Anna C.; Buonomano, Dean V.

    2015-01-01

    Time is central to cognition. However, the neural basis for time-dependent cognition remains poorly understood. We explore how the temporal features of neural activity in cortical circuits and their capacity for plasticity can contribute to time-dependent cognition over short time scales. This neural activity is linked to cognition that operates in the present or anticipates events or stimuli in the near future. We focus on deliberation and planning in the context of decision making as a cognitive process that integrates information across time. We progress to consider how temporal expectations of the future modulate perception. We propose that understanding the neural basis for how the brain tells time and operates in time will be necessary to develop general models of cognition. SIGNIFICANCE STATEMENT Time is central to cognition. However, the neural basis for time-dependent cognition remains poorly understood. We explore how the temporal features of neural activity in cortical circuits and their capacity for plasticity can contribute to time-dependent cognition over short time scales. We propose that understanding the neural basis for how the brain tells time and operates in time will be necessary to develop general models of cognition. PMID:26468192

  9. Retinal Atherosclerosis, Ophthalmologically Reported and Documented with OSA in 1987, is now Totally Reversed, and Recorded, Photographically. The Supposition then was that Equivalent Cortical Damage could Respond to the same Healing Protocol.

    NASA Astrophysics Data System (ADS)

    Niemi, Paul N.; O., D.; Mc Leod, David M.; Mc Leod, Roger D.

    2007-10-01

    Documented retinal atherosclerosis, ``silver streaking'' of retinal capillaries, was reported and documented with OSA, in October 1987. That retinal damage, despite claims it usually progresses and is nonreversible, is now completely cleared. The original OSA presentation proposed that equivalent cortical damage was probably present throughout the brain at that time, as attested by failing short-term memory performance and transient ischemic attacks, TIAs, brief vision strokes. The supposition then was that ophthalmologic access to the retina, by some accounts the progenitor of all brain evolution, could provide a means of monitoring the actual circulatory state of inaccessible parts of the brain. To the extent that retinal health was naturopathically restored, and memory performance seems also to have significantly kept pace, is it a tenable premise that such protocols have rather general importance? Can applied optics help establish more appropriate diagnoses, and evaluate treatments for dementia and Alzheimer's disease?

  10. Toward more versatile and intuitive cortical brain machine interfaces

    PubMed Central

    Andersen, Richard A.; Kellis, Spencer; Klaes, Christian; Aflalo, Tyson

    2015-01-01

    Brain machine interfaces have great potential in neuroprosthetic applications to assist patients with brain injury and neurodegenerative diseases. One type of BMI is a cortical motor prosthetic which is used to assist paralyzed subjects. Motor prosthetics to date have typically used the motor cortex as a source of neural signals for controlling external devices. The review will focus on several new topics in the arena of cortical prosthetics. These include using 1) recordings from cortical areas outside motor cortex; 2) local field potentials (LFPs) as a source of recorded signals; 3) somatosensory feedback for more dexterous control of robotics; and 4) new decoding methods that work in concert to form an ecology of decode algorithms. These new advances hold promise in greatly accelerating the applicability and ease of operation of motor prosthetics. PMID:25247368

  11. Electrophysiologic analysis of regional cortical maturation.

    PubMed

    Vaughan, H G

    1975-10-01

    Some issues in the study of human neurobehavioral development are briefly set forth. Attention is called to the limitations of strictly structural and behavioral approaches. The value of correlative morphophysiological and psychophysiological investigations is emphasized. By averaging brain activity with respect to stimuli and motor responses, event-related cortical potentials (ERP) can be reliably detected in the scalp EEG. Longitudinal topographic studies of ERP permit the definition of a sequence of regional cortical maturation during infancy and childhood. We have found that evoked potentials in the three major sensory modalities arise from both primary and secondary projection areas by 30 weeks of conceptional age. Frontocentral responses appear shortly thereafter. Thus, cortical mechanisms show a precocious development of electrogenesis which indicates the possibility for an early environmental impact on brain maturation. In contrast to the evoked potentials, association cortex potentials (ACP) do not seem to appear until early childhood. The behavioral significance of these neuroelectric phenomena is being sought in studies employing techniques which permit the concurrent recording of brain activity and behavioral responses in the waking infant and child. Some of the problems confronting the application of these methods to studies of infants are outlined. PMID:1203402

  12. Cortico-cortical communication dynamics

    PubMed Central

    Roland, Per E.; Hilgetag, Claus C.; Deco, Gustavo

    2014-01-01

    In principle, cortico-cortical communication dynamics is simple: neurons in one cortical area communicate by sending action potentials that release glutamate and excite their target neurons in other cortical areas. In practice, knowledge about cortico-cortical communication dynamics is minute. One reason is that no current technique can capture the fast spatio-temporal cortico-cortical evolution of action potential transmission and membrane conductances with sufficient spatial resolution. A combination of optogenetics and monosynaptic tracing with virus can reveal the spatio-temporal cortico-cortical dynamics of specific neurons and their targets, but does not reveal how the dynamics evolves under natural conditions. Spontaneous ongoing action potentials also spread across cortical areas and are difficult to separate from structured evoked and intrinsic brain activity such as thinking. At a certain state of evolution, the dynamics may engage larger populations of neurons to drive the brain to decisions, percepts and behaviors. For example, successfully evolving dynamics to sensory transients can appear at the mesoscopic scale revealing how the transient is perceived. As a consequence of these methodological and conceptual difficulties, studies in this field comprise a wide range of computational models, large-scale measurements (e.g., by MEG, EEG), and a combination of invasive measurements in animal experiments. Further obstacles and challenges of studying cortico-cortical communication dynamics are outlined in this critical review. PMID:24847217

  13. Real-time, time-frequency mapping of event-related cortical activation

    NASA Astrophysics Data System (ADS)

    Cheung, Connie; Chang, Edward F.

    2012-08-01

    Functional mapping of eloquent cortex is a common and necessary component of neurosurgical operative planning. Current electrical stimulation-based techniques are inefficient, can evoke seizures and are prone to false-negative results. Here, we present a novel cortical mapping system that extracts event-related neural activity from passive electrocorticographic recordings to quickly and accurately localize sensory and motor cortices using the precise temporal properties of spectral alteration. This procedure generates a robust functional motor and sensory cortical map in seconds, and usually with less than five to ten trial events. Our algorithm demonstrates high concordance with results derived using independent electrical cortical stimulation mapping.

  14. Modeling cortical circuits.

    SciTech Connect

    Rohrer, Brandon Robinson; Rothganger, Fredrick H.; Verzi, Stephen J.; Xavier, Patrick Gordon

    2010-09-01

    The neocortex is perhaps the highest region of the human brain, where audio and visual perception takes place along with many important cognitive functions. An important research goal is to describe the mechanisms implemented by the neocortex. There is an apparent regularity in the structure of the neocortex [Brodmann 1909, Mountcastle 1957] which may help simplify this task. The work reported here addresses the problem of how to describe the putative repeated units ('cortical circuits') in a manner that is easily understood and manipulated, with the long-term goal of developing a mathematical and algorithmic description of their function. The approach is to reduce each algorithm to an enhanced perceptron-like structure and describe its computation using difference equations. We organize this algorithmic processing into larger structures based on physiological observations, and implement key modeling concepts in software which runs on parallel computing hardware.

  15. Lifespan Differences in Cortical Dynamics of Auditory Perception

    ERIC Educational Resources Information Center

    Muller, Viktor; Gruber, Walter; Klimesch, Wolfgang; Lindenberger, Ulman

    2009-01-01

    Using electroencephalographic recordings (EEG), we assessed differences in oscillatory cortical activity during auditory-oddball performance between children aged 9-13 years, younger adults, and older adults. From childhood to old age, phase synchronization increased within and between electrodes, whereas whole power and evoked power decreased. We…

  16. Malformations of cortical development and aberrant cortical networks: epileptogenesis and functional organization.

    PubMed

    Guerrini, Renzo; Barba, Carmen

    2010-12-01

    Malformations of cortical development are a major cause of drug-resistant epilepsy. Focal cortical dysplasia, heterotopia, and polymicrogyria are often manifested as discrete areas of abnormal neuronal migration and improper development of the cerebral cortex. Some of the patients harboring these malformations have obvious neurologic impairment, but others show unexpected deficits that are detectable only by screening. The role of surgical treatment of epilepsy due to localized malformations of cortical development is now established. However, its technical application can be challenging in that localization of function based on anatomic landmarks may not be reliable. Intracranial recordings have shown a high propensity for complex epileptogenic networks that may include remote cortical and subcortical regions. The MRI visible area of cortical abnormality should therefore be regarded as just an indicator of the epileptogenic zone rather than its tangible substrate. Completeness of resection, after delineation of the ictal onset zone, a key factor for successful epilepsy surgery, may be particularly difficult, and invasive EEG monitoring is necessary in most patients. Neural plasticity issues are of primary importance to surgical planning as the possibility of removing eloquent cortex permits more complete procedures with potentially higher rates of success. However, the functional consequences of malformative lesions are still poorly understood; conservation of function in the dysplastic cortex, its atypical representation, and relocation outside the malformed area are all possible. Surgical planning for associated epilepsy should therefore be based on individual assessments of structural imaging and of the major functions relevant to the area in question in the individual patient. PMID:21076336

  17. Whose Cortical Column Would that Be?

    PubMed Central

    da Costa, Nuno Maçarico; Martin, Kevan A. C.

    2010-01-01

    The cortical column has been an invaluable concept to explain the functional organization of the neocortex. While this idea was born out of experiments that cleverly combined electrophysiological recordings with anatomy, no one has ‘seen’ the anatomy of a column. All we know is that when we record through the cortex of primates, ungulates, and carnivores in a trajectory perpendicular to its surface there is a remarkable constancy in the receptive field properties of the neurons regarding one set of stimulus features. There is no obvious morphological analog for this functional architecture, in fact much of the anatomical data seems to challenge it. Here we describe historically the origins of the concept of the cortical column and the struggles of the pioneers to define the columnar architecture. We suggest that in the concept of a ‘canonical circuit’ we may find the means to reconcile the structure of neocortex with its functional architecture. The canonical microcircuit respects the known connectivity of the neocortex, and it is flexible enough to change transiently the architecture of its network in order to perform the required computations. PMID:20640245

  18. Changes of cortical excitability in patients with upper limb amputation.

    PubMed

    Schwenkreis, P; Witscher, K; Janssen, F; Dertwinkel, R; Zenz, M; Malin, J P; Tegenthoff, M

    2000-10-27

    In our study we wanted to assess motor excitability in patients with upper limb amputation by means of transcranial magnetic stimulation (TMS). In 12 patients, TMS was applied using a paired pulse paradigm in order to test cortico-cortical excitability. Additional parameters of motor excitability like motor threshold and cortical silent period were also measured. Recordings from the amputated side were compared to the contralateral side and to healthy controls. We found a significant reduction of intracortical inhibition in forearm amputees and an enhancement of intracortical facilitation in upper arm amputees on the affected side. We conclude that after upper limb amputation, changes in the activity of intracortical interneuronal circuits appear in the affected hemisphere. These changes may depend on the level of amputation, and be the base of cortical reorganization. PMID:11027854

  19. [Cortical control of saccades].

    PubMed

    Pierrot-Deseilligny, C

    1989-01-01

    Among saccades triggered by the cerebral cortex, visually guided saccades are the best known and their cortical control is reviewed here. Only two immediately supra-reticular structures are able to trigger saccades (whatever their type): the frontal eye fields (FEF) and the superior colliculus (SC). These structures control two parallel excitatory pathways, which can replace each other in the event of lesion. Experimental findings have suggested that the colliculo-reticular pathway would, in the normal state, play the main role in the triggering of reflexive visually guided saccades. Furthermore experimental and clinical data suggest that the SC would receive an excitatory afference from the posterior part of the intraparietal sulcus, which could be involved in the triggering of these saccades. The parietal lobe could influence the SC by increasing the pre-excitation due to the onset of the visual target. There are also inhibitory pathways which prevent saccades, in particular during fixation. Two groups of tonic neurons inhibit the excitatory pathways. These are the omnipause neurons and the neurons of the substantia nigra (pars reticulata), which project upon the premotor reticular formations and the SC respectively. The pathways projecting upon these 2 types of neurons are multiple and still little known. Nevertheless, some arguments suggest that the frontal lobe partly controls inhibition. These arguments are based on a somewhat disinhibited triggering of reflexive visually guided saccades in focal or degenerative (progressive supranuclear palsy) frontal lesions. The prefrontal cortex could be involved in inhibition control, and it could act functionally above the FEF. PMID:2682934

  20. Anesthesia differentially modulates spontaneous network dynamics by cortical area and layer.

    PubMed

    Sellers, Kristin K; Bennett, Davis V; Hutt, Axel; Fröhlich, Flavio

    2013-12-01

    Anesthesia is widely used in medicine and research to achieve altered states of consciousness and cognition. Whereas changes to macroscopic cortical activity patterns by anesthesia measured at the spatial resolution of electroencephalography have been widely studied, modulation of mesoscopic and microscopic network dynamics by anesthesia remain poorly understood. To address this gap in knowledge, we recorded spontaneous mesoscopic (local field potential) and microscopic (multiunit activity) network dynamics in primary visual cortex (V1) and prefrontal cortex (PFC) of awake and isoflurane anesthetized ferrets (Mustela putoris furo). This approach allowed for examination of activity as a function of cortical area, cortical layer, and anesthetic depth with much higher spatial and temporal resolution than in previous studies. We hypothesized that a primary sensory area and an association cortical area would exhibit different patterns of network modulation by anesthesia due to their different functional roles. Indeed, we found effects specific to cortical area and cortical layer. V1 exhibited minimal changes in rhythmic structure with anesthesia but differential modulation of input layer IV. In contrast, anesthesia profoundly altered spectral power in PFC, with more uniform modulation across cortical layers. Our results demonstrate that anesthesia modulates spontaneous cortical activity in an area- and layer-specific manner. These finding provide the basis for 1) refining anesthesia monitoring algorithms, 2) reevaluating the large number of systems neuroscience studies performed in anesthetized animals, and 3) increasing our understanding of differential dynamics across cortical layers and areas. PMID:24047911

  1. Decoding of Covert Vowel Articulation Using Electroencephalography Cortical Currents.

    PubMed

    Yoshimura, Natsue; Nishimoto, Atsushi; Belkacem, Abdelkader Nasreddine; Shin, Duk; Kambara, Hiroyuki; Hanakawa, Takashi; Koike, Yasuharu

    2016-01-01

    With the goal of providing assistive technology for the communication impaired, we proposed electroencephalography (EEG) cortical currents as a new approach for EEG-based brain-computer interface spellers. EEG cortical currents were estimated with a variational Bayesian method that uses functional magnetic resonance imaging (fMRI) data as a hierarchical prior. EEG and fMRI data were recorded from ten healthy participants during covert articulation of Japanese vowels /a/ and /i/, as well as during a no-imagery control task. Applying a sparse logistic regression (SLR) method to classify the three tasks, mean classification accuracy using EEG cortical currents was significantly higher than that using EEG sensor signals and was also comparable to accuracies in previous studies using electrocorticography. SLR weight analysis revealed vertices of EEG cortical currents that were highly contributive to classification for each participant, and the vertices showed discriminative time series signals according to the three tasks. Furthermore, functional connectivity analysis focusing on the highly contributive vertices revealed positive and negative correlations among areas related to speech processing. As the same findings were not observed using EEG sensor signals, our results demonstrate the potential utility of EEG cortical currents not only for engineering purposes such as brain-computer interfaces but also for neuroscientific purposes such as the identification of neural signaling related to language processing. PMID:27199638

  2. Decoding of Covert Vowel Articulation Using Electroencephalography Cortical Currents

    PubMed Central

    Yoshimura, Natsue; Nishimoto, Atsushi; Belkacem, Abdelkader Nasreddine; Shin, Duk; Kambara, Hiroyuki; Hanakawa, Takashi; Koike, Yasuharu

    2016-01-01

    With the goal of providing assistive technology for the communication impaired, we proposed electroencephalography (EEG) cortical currents as a new approach for EEG-based brain-computer interface spellers. EEG cortical currents were estimated with a variational Bayesian method that uses functional magnetic resonance imaging (fMRI) data as a hierarchical prior. EEG and fMRI data were recorded from ten healthy participants during covert articulation of Japanese vowels /a/ and /i/, as well as during a no-imagery control task. Applying a sparse logistic regression (SLR) method to classify the three tasks, mean classification accuracy using EEG cortical currents was significantly higher than that using EEG sensor signals and was also comparable to accuracies in previous studies using electrocorticography. SLR weight analysis revealed vertices of EEG cortical currents that were highly contributive to classification for each participant, and the vertices showed discriminative time series signals according to the three tasks. Furthermore, functional connectivity analysis focusing on the highly contributive vertices revealed positive and negative correlations among areas related to speech processing. As the same findings were not observed using EEG sensor signals, our results demonstrate the potential utility of EEG cortical currents not only for engineering purposes such as brain-computer interfaces but also for neuroscientific purposes such as the identification of neural signaling related to language processing. PMID:27199638

  3. Cortical sensory plasticity in a model of migraine with aura

    PubMed Central

    Theriot, Jeremy J.; Toga, Arthur W.; Prakash, Neal; Ju, Y. Sungtaek; Brennan, K.C.

    2012-01-01

    The migraine attack is characterized by alterations in sensory perception, such as photophobia or allodynia, which have in common an uncomfortable amplification of the percept. It is not known how these changes arise. We evaluated the ability of cortical spreading depression (CSD), the proposed mechanism of the migraine aura, to shape the cortical activity that underlies sensory perception. We measured forepaw- and hindpaw-evoked sensory responses in rat, before and after CSD, using multi-electrode array recordings and 2-dimensional optical spectroscopy. CSD significantly altered cortical sensory processing on a timescale compatible with the duration of the migraine attack. Both electrophysiological and hemodynamic maps had a reduced surface area (were sharpened) after CSD. Electrophysiological responses were potentiated at the receptive field center, but suppressed in surround regions. Finally, the normal adaptation of sensory evoked responses was attenuated at the receptive field center. In summary, we show that CSD induces changes in the evoked cortical response that are consistent with known mechanisms of cortical plasticity. These mechanisms provide a novel neurobiological substrate to explain the sensory alterations of the migraine attack. PMID:23115163

  4. Antisaccade task reflects cortical involvement in mild cognitive impairment

    PubMed Central

    Mirsky, Jacob B.; Kong, Erwin L.; Dickerson, Bradford C.; Miller, Bruce L.; Kramer, Joel H.; Boxer, Adam L.

    2013-01-01

    Objective: The aims of this study were to examine executive dysfunction using an antisaccade (AS) task in normal elderly (NE) and patients with mild cognitive impairment (MCI) and Alzheimer disease (AD) as well as to evaluate the relationship between AS performance and cortical thinning within AD-associated regions. Methods: We recorded eye movements in 182 subjects (NE: 118; MCI: 36; AD: 28) during an AS task. We also performed neuropsychological measures of executive function for comparison. Brain MRI scans were collected on most subjects, and cortical thickness was determined in 9 regions known to exhibit atrophy in AD dementia (“AD signature”). We investigated the relationships between AS and neuropsychological performance, as well as possible correlations between AS performance and cortical thickness. Results: AS performance in MCI resembled that in NE; subjects with AD were impaired relative to both MCI and NE. In all subjects, AS performance correlated with neuropsychological measures of executive function, even after controlling for disease severity. In the subjects with MCI but not in NE, cortical thickness in frontoparietal AD signature regions correlated with AS performance. Conclusions: The AS task is a useful measure of executive function across the AD spectrum. In MCI, AS performance may reflect disease burden within cortical brain regions involved in oculomotor control; however, AS impairments in NE may have etiologies other than incipient AD. PMID:23986300

  5. Muscle synergy patterns as physiological markers of motor cortical damage

    PubMed Central

    Cheung, Vincent C. K.; Turolla, Andrea; Agostini, Michela; Silvoni, Stefano; Bennis, Caoimhe; Kasi, Patrick; Paganoni, Sabrina; Bonato, Paolo; Bizzi, Emilio

    2012-01-01

    The experimental findings herein reported are aimed at gaining a perspective on the complex neural events that follow lesions of the motor cortical areas. Cortical damage, whether by trauma or stroke, interferes with the flow of descending signals to the modular interneuronal structures of the spinal cord. These spinal modules subserve normal motor behaviors by activating groups of muscles as individual units (muscle synergies). Damage to the motor cortical areas disrupts the orchestration of the modules, resulting in abnormal movements. To gain insights into this complex process, we recorded myoelectric signals from multiple upper-limb muscles in subjects with cortical lesions. We used a factorization algorithm to identify the muscle synergies. Our factorization analysis revealed, in a quantitative way, three distinct patterns of muscle coordination—including preservation, merging, and fractionation of muscle synergies—that reflect the multiple neural responses that occur after cortical damage. These patterns varied as a function of both the severity of functional impairment and the temporal distance from stroke onset. We think these muscle-synergy patterns can be used as physiological markers of the status of any patient with stroke or trauma, thereby guiding the development of different rehabilitation approaches, as well as future physiological experiments for a further understanding of postinjury mechanisms of motor control and recovery. PMID:22908288

  6. Primary auditory cortical responses to electrical stimulation of the thalamus.

    PubMed

    Atencio, Craig A; Shih, Jonathan Y; Schreiner, Christoph E; Cheung, Steven W

    2014-03-01

    Cochlear implant electrical stimulation of the auditory system to rehabilitate deafness has been remarkably successful. Its deployment requires both an intact auditory nerve and a suitably patent cochlear lumen. When disease renders prerequisite conditions impassable, such as in neurofibromatosis type II and cochlear obliterans, alternative treatment targets are considered. Electrical stimulation of the cochlear nucleus and midbrain in humans has delivered encouraging clinical outcomes, buttressing the promise of central auditory prostheses to mitigate deafness in those who are not candidates for cochlear implantation. In this study we explored another possible implant target: the auditory thalamus. In anesthetized cats, we first presented pure tones to determine frequency preferences of thalamic and cortical sites. We then electrically stimulated tonotopically organized thalamic sites while recording from primary auditory cortical sites using a multichannel recording probe. Cathode-leading biphasic thalamic stimulation thresholds that evoked cortical responses were much lower than published accounts of cochlear and midbrain stimulation. Cortical activation dynamic ranges were similar to those reported for cochlear stimulation, but they were narrower than those found through midbrain stimulation. Our results imply that thalamic stimulation can activate auditory cortex at low electrical current levels and suggest an auditory thalamic implant may be a viable central auditory prosthesis. PMID:24335216

  7. Cortical network architecture for context processing in primate brain

    PubMed Central

    Chao, Zenas C; Nagasaka, Yasuo; Fujii, Naotaka

    2015-01-01

    Context is information linked to a situation that can guide behavior. In the brain, context is encoded by sensory processing and can later be retrieved from memory. How context is communicated within the cortical network in sensory and mnemonic forms is unknown due to the lack of methods for high-resolution, brain-wide neuronal recording and analysis. Here, we report the comprehensive architecture of a cortical network for context processing. Using hemisphere-wide, high-density electrocorticography, we measured large-scale neuronal activity from monkeys observing videos of agents interacting in situations with different contexts. We extracted five context-related network structures including a bottom-up network during encoding and, seconds later, cue-dependent retrieval of the same network with the opposite top-down connectivity. These findings show that context is represented in the cortical network as distributed communication structures with dynamic information flows. This study provides a general methodology for recording and analyzing cortical network neuronal communication during cognition. DOI: http://dx.doi.org/10.7554/eLife.06121.001 PMID:26416139

  8. Diaphragmatic activity induced by cortical stimulation: surface versus esophageal electrodes.

    PubMed

    Gea, J; Espadaler, J M; Guiu, R; Aran, X; Seoane, L; Broquetas, J M

    1993-02-01

    Evoked responses of the diaphragm can be induced by magnetic cortical stimulation and recorded by either surface or esophageal electrodes. The former recording system is tolerated better by the patient but has potential problems with the specificity of the diaphragmatic signal. This study compares the responses of the diaphragm to cortical stimulation that were recorded simultaneously with surface and esophageal electrodes on seven patients (61 +/- 4 yr) with chronic obstructive pulmonary diseases. Stimuli were delivered in three ventilatory conditions: at baseline, during deep breathing, and during voluntary panting. No differences were observed between results recorded by surface and esophageal electrodes [amplitude of the compound motor of the action potential (CMAP), 0.8 +/- 0.1 vs. 0.8 +/- 0.1 mV, NS; latency, 13.1 +/- 0.4 vs. 12.6 +/- 0.5 ms, NS]. In addition, significant correlations were found (CMAP, r = 0.77, P < 0.001; latency, r = 0.71, P = 0.002). The concordance analysis, however, indicated some dissimilarity between the recordings of the electrodes (CMAP, R1 = 0.31; latency, R1 = 0.26). These differences may be due to the area of the muscle mainly recorded by each electrode and/or to the additional activity from other muscles recorded by surface electrodes. On the other hand, the diaphragmatic responses observed in these patients with chronic obstructive pulmonary diseases were similar to those previously reported in healthy subjects. PMID:8458780

  9. Imprinting and recalling cortical ensembles.

    PubMed

    Carrillo-Reid, Luis; Yang, Weijian; Bando, Yuki; Peterka, Darcy S; Yuste, Rafael

    2016-08-12

    Neuronal ensembles are coactive groups of neurons that may represent building blocks of cortical circuits. These ensembles could be formed by Hebbian plasticity, whereby synapses between coactive neurons are strengthened. Here we report that repetitive activation with two-photon optogenetics of neuronal populations from ensembles in the visual cortex of awake mice builds neuronal ensembles that recur spontaneously after being imprinted and do not disrupt preexisting ones. Moreover, imprinted ensembles can be recalled by single- cell stimulation and remain coactive on consecutive days. Our results demonstrate the persistent reconfiguration of cortical circuits by two-photon optogenetics into neuronal ensembles that can perform pattern completion. PMID:27516599

  10. Spatial Coherence in Auditory Cortical Activity Fluctuations

    NASA Astrophysics Data System (ADS)

    Yoshida, Takamasa; Katura, Takusige; Yamazaki, Kyoko; Tanaka, Shigeru; Iwamoto, Mitsumasa; Tanaka, Naoki

    2007-07-01

    We examined activity fluctuations as ongoing and spontaneous activities that were recorded with voltage sensitive dye imaging in the auditory cortex of guinea pigs. We investigated whether such activities demonstrated spatial coherence, which represents the cortical functional organization. We used independent component analysis to extract neural activities from observed signals and a scaled signal-plus-noise model to estimate ongoing activities from the neural activities including response components. We mapped the correlation between the time courses in each channel and in the others for the whole observed region. Ongoing and spontaneous activities in the auditory cortex were found to have strong spatial coherence corresponding to the tonotopy, which is one of auditory functional organization.

  11. Vibrotactile aid and brain cortical activity.

    PubMed

    Suárez, H; Cibils, D; Caffa, C; Silveira, A; Basalo, S; Svirsky, M

    1997-03-01

    Six profoundly deaf patients were studied with mapping evoked potentials (MEP) using an acoustic signal passed through the vibrotactile prosthesis. This stimulus produced an activation of the central sulcus brain cortex. When the proSthesis was placed in the presenternal area it showed N1 P1 potentials with higher voltage and a more defined cortical dipole inversion than when the prosthesis was placed in the arm or abdomen: thus the presternal stimulation is considered an adequate place for the use of vibrotactile stimulation. The MEP were recorded in 2 patients after a period of audiological training and they showed new earlier potentials. These suggest plastic changes in the processing of an acoustic signal sent from the presternal skin by the somatosensory pathway after training and involving learning procedures. PMID:9105450

  12. Cortical representation area of human dental pulp.

    PubMed

    Kubo, K; Shibukawa, Y; Shintani, M; Suzuki, T; Ichinohe, T; Kaneko, Y

    2008-04-01

    To elucidate the dental pulp-representing area in the human primary somatosensory cortex and the presence of A-beta fibers in dental pulp, we recorded somatosensory-evoked magnetic fields from the cortex in seven healthy persons using magnetoencephalography. Following non-painful electrical stimulation of the right maxillary first premolar dental pulp, short latency (27 ms) cortical responses on the magnetic waveforms were observed. However, no response was seen when stimulation was applied to pulpless teeth, such as devitalized teeth. The current source generating the early component of the magnetic fields was located anterior-inferiorly compared with the locations for the hand area in the primary somatosensory cortex. These results demonstrate the dental pulp representation area in the primary somatosensory cortex, and that it receives input from intradental A-beta neurons, providing a detailed organizational map of the orofacial area, by adding dental pulp to the classic "sensory homunculus". PMID:18362319

  13. Cortical information flow during flexible sensorimotor decisions.

    PubMed

    Siegel, Markus; Buschman, Timothy J; Miller, Earl K

    2015-06-19

    During flexible behavior, multiple brain regions encode sensory inputs, the current task, and choices. It remains unclear how these signals evolve. We simultaneously recorded neuronal activity from six cortical regions [middle temporal area (MT), visual area four (V4), inferior temporal cortex (IT), lateral intraparietal area (LIP), prefrontal cortex (PFC), and frontal eye fields (FEF)] of monkeys reporting the color or motion of stimuli. After a transient bottom-up sweep, there was a top-down flow of sustained task information from frontoparietal to visual cortex. Sensory information flowed from visual to parietal and prefrontal cortex. Choice signals developed simultaneously in frontoparietal regions and travelled to FEF and sensory cortex. This suggests that flexible sensorimotor choices emerge in a frontoparietal network from the integration of opposite flows of sensory and task information. PMID:26089513

  14. Detecting a Cortical Fingerprint of Parkinson's Disease for Closed-Loop Neuromodulation

    PubMed Central

    Kern, Kevin; Naros, Georgios; Braun, Christoph; Weiss, Daniel; Gharabaghi, Alireza

    2016-01-01

    Recent evidence suggests that deep brain stimulation (DBS) of the subthalamic nucleus (STN) in Parkinson's disease (PD) mediates its clinical effects by modulating cortical oscillatory activity, presumably via a direct cortico-subthalamic connection. This observation might pave the way for novel closed-loop approaches comprising a cortical sensor. Enhanced beta oscillations (13-35 Hz) have been linked to the pathophysiology of PD and may serve as such a candidate marker to localize a cortical area reliably modulated by DBS. However, beta-oscillations are widely distributed over the cortical surface, necessitating an additional signal source for spotting the cortical area linked to the pathologically synchronized cortico-subcortical motor network. In this context, both cortico-subthalamic coherence and cortico-muscular coherence (CMC) have been studied in PD patients. Whereas, the former requires invasive recordings, the latter allows for non-invasive detection, but displays a rather distributed cortical synchronization pattern in motor tasks. This distributed cortical representation may conflict with the goal of detecting a cortical localization with robust biomarker properties which is detectable on a single subject basis. We propose that this limitation could be overcome when recording CMC at rest. We hypothesized that—unlike healthy subjects—PD would show CMC at rest owing to the enhanced beta oscillations observed in PD. By performing source space analysis of beta CMC recorded during resting-state magnetoencephalography, we provide preliminary evidence in one patient for a cortical hot spot that is modulated most strongly by subthalamic DBS. Such a spot would provide a prominent target region either for direct neuromodulation or for placing a potential sensor in closed-loop DBS approaches, a proposal that requires investigation in a larger cohort of PD patients. PMID:27065781

  15. Detecting a Cortical Fingerprint of Parkinson's Disease for Closed-Loop Neuromodulation.

    PubMed

    Kern, Kevin; Naros, Georgios; Braun, Christoph; Weiss, Daniel; Gharabaghi, Alireza

    2016-01-01

    Recent evidence suggests that deep brain stimulation (DBS) of the subthalamic nucleus (STN) in Parkinson's disease (PD) mediates its clinical effects by modulating cortical oscillatory activity, presumably via a direct cortico-subthalamic connection. This observation might pave the way for novel closed-loop approaches comprising a cortical sensor. Enhanced beta oscillations (13-35 Hz) have been linked to the pathophysiology of PD and may serve as such a candidate marker to localize a cortical area reliably modulated by DBS. However, beta-oscillations are widely distributed over the cortical surface, necessitating an additional signal source for spotting the cortical area linked to the pathologically synchronized cortico-subcortical motor network. In this context, both cortico-subthalamic coherence and cortico-muscular coherence (CMC) have been studied in PD patients. Whereas, the former requires invasive recordings, the latter allows for non-invasive detection, but displays a rather distributed cortical synchronization pattern in motor tasks. This distributed cortical representation may conflict with the goal of detecting a cortical localization with robust biomarker properties which is detectable on a single subject basis. We propose that this limitation could be overcome when recording CMC at rest. We hypothesized that-unlike healthy subjects-PD would show CMC at rest owing to the enhanced beta oscillations observed in PD. By performing source space analysis of beta CMC recorded during resting-state magnetoencephalography, we provide preliminary evidence in one patient for a cortical hot spot that is modulated most strongly by subthalamic DBS. Such a spot would provide a prominent target region either for direct neuromodulation or for placing a potential sensor in closed-loop DBS approaches, a proposal that requires investigation in a larger cohort of PD patients. PMID:27065781

  16. Cortical inhibitory deficits in premanifest and early Huntington's disease.

    PubMed

    Philpott, April L; Cummins, Tarrant D R; Bailey, Neil W; Churchyard, Andrew; Fitzgerald, Paul B; Georgiou-Karistianis, Nellie

    2016-01-01

    Although progress has been made towards understanding the gross cortical and subcortical pathology of Huntington's disease (HD), there remains little understanding of the progressive pathophysiological changes that occur in the brain circuits underlying the disease. Transcranial magnetic stimulation (TMS) enables investigation of the functional integrity of cortico-subcortical pathways, yet it has not been widely applied in HD research to date. This study sought to characterise profiles of cortical excitability, including inhibition and facilitation, in groups of premanifest and symptomatic HD participants via the use of TMS. We also investigated the clinical, neurocognitive and psychiatric correlates of cortical excitability to better understand the development of phenotypic heterogeneity. The sample comprised 16 premanifest HD, 12 early symptomatic HD and 17 healthy control participants. Single- and paired-pulse TMS protocols were administered to the left primary motor cortex, with surface electromyography recorded from the abductor pollicis brevis muscle. Short-interval cortical inhibition was significantly reduced in symptomatic HD, compared with premanifest HD and controls, and was significantly correlated with pathological burden and neurocognitive performance. There was also reduced long-interval cortical inhibition in both premanifest and symptomatic HD, compared with controls, which was associated with pathological burden and psychiatric disturbances. Motor thresholds, cortical silent periods and intracortical facilitation did not differ across groups. Our results provide important new insights into pathophysiological changes in cortico-subcortical circuits across disease stages in HD. We propose that neurophysiological measures obtained via TMS have potential utility as endophenotypic biomarkers in HD, given their association with both pathological burden and clinical phenotype. PMID:26416671

  17. Maximizing Sensory Dynamic Range by Tuning the Cortical State to Criticality

    PubMed Central

    Gautam, Shree Hari; Hoang, Thanh T.; McClanahan, Kylie; Grady, Stephen K.; Shew, Woodrow L.

    2015-01-01

    Modulation of interactions among neurons can manifest as dramatic changes in the state of population dynamics in cerebral cortex. How such transitions in cortical state impact the information processing performed by cortical circuits is not clear. Here we performed experiments and computational modeling to determine how somatosensory dynamic range depends on cortical state. We used microelectrode arrays to record ongoing and whisker stimulus-evoked population spiking activity in somatosensory cortex of urethane anesthetized rats. We observed a continuum of different cortical states; at one extreme population activity exhibited small scale variability and was weakly correlated, the other extreme had large scale fluctuations and strong correlations. In experiments, shifts along the continuum often occurred naturally, without direct manipulation. In addition, in both the experiment and the model we directly tuned the cortical state by manipulating inhibitory synaptic interactions. Our principal finding was that somatosensory dynamic range was maximized in a specific cortical state, called criticality, near the tipping point midway between the ends of the continuum. The optimal cortical state was uniquely characterized by scale-free ongoing population dynamics and moderate correlations, in line with theoretical predictions about criticality. However, to reproduce our experimental findings, we found that existing theory required modifications which account for activity-dependent depression. In conclusion, our experiments indicate that in vivo sensory dynamic range is maximized near criticality and our model revealed an unanticipated role for activity-dependent depression in this basic principle of cortical function. PMID:26623645

  18. Maximizing Sensory Dynamic Range by Tuning the Cortical State to Criticality.

    PubMed

    Gautam, Shree Hari; Hoang, Thanh T; McClanahan, Kylie; Grady, Stephen K; Shew, Woodrow L

    2015-12-01

    Modulation of interactions among neurons can manifest as dramatic changes in the state of population dynamics in cerebral cortex. How such transitions in cortical state impact the information processing performed by cortical circuits is not clear. Here we performed experiments and computational modeling to determine how somatosensory dynamic range depends on cortical state. We used microelectrode arrays to record ongoing and whisker stimulus-evoked population spiking activity in somatosensory cortex of urethane anesthetized rats. We observed a continuum of different cortical states; at one extreme population activity exhibited small scale variability and was weakly correlated, the other extreme had large scale fluctuations and strong correlations. In experiments, shifts along the continuum often occurred naturally, without direct manipulation. In addition, in both the experiment and the model we directly tuned the cortical state by manipulating inhibitory synaptic interactions. Our principal finding was that somatosensory dynamic range was maximized in a specific cortical state, called criticality, near the tipping point midway between the ends of the continuum. The optimal cortical state was uniquely characterized by scale-free ongoing population dynamics and moderate correlations, in line with theoretical predictions about criticality. However, to reproduce our experimental findings, we found that existing theory required modifications which account for activity-dependent depression. In conclusion, our experiments indicate that in vivo sensory dynamic range is maximized near criticality and our model revealed an unanticipated role for activity-dependent depression in this basic principle of cortical function. PMID:26623645

  19. Wireless Cortical Brain-Machine Interface for Whole-Body Navigation in Primates

    PubMed Central

    Rajangam, Sankaranarayani; Tseng, Po-He; Yin, Allen; Lehew, Gary; Schwarz, David; Lebedev, Mikhail A.; Nicolelis, Miguel A. L.

    2016-01-01

    Several groups have developed brain-machine-interfaces (BMIs) that allow primates to use cortical activity to control artificial limbs. Yet, it remains unknown whether cortical ensembles could represent the kinematics of whole-body navigation and be used to operate a BMI that moves a wheelchair continuously in space. Here we show that rhesus monkeys can learn to navigate a robotic wheelchair, using their cortical activity as the main control signal. Two monkeys were chronically implanted with multichannel microelectrode arrays that allowed wireless recordings from ensembles of premotor and sensorimotor cortical neurons. Initially, while monkeys remained seated in the robotic wheelchair, passive navigation was employed to train a linear decoder to extract 2D wheelchair kinematics from cortical activity. Next, monkeys employed the wireless BMI to translate their cortical activity into the robotic wheelchair’s translational and rotational velocities. Over time, monkeys improved their ability to navigate the wheelchair toward the location of a grape reward. The navigation was enacted by populations of cortical neurons tuned to whole-body displacement. During practice with the apparatus, we also noticed the presence of a cortical representation of the distance to reward location. These results demonstrate that intracranial BMIs could restore whole-body mobility to severely paralyzed patients in the future. PMID:26938468

  20. Communication Structure of Cortical Networks

    PubMed Central

    da Fontoura Costa, Luciano; Batista, João Luiz B.; Ascoli, Giorgio A.

    2011-01-01

    Large-scale cortical networks exhibit characteristic topological properties that shape communication between brain regions and global cortical dynamics. Analysis of complex networks allows the description of connectedness, distance, clustering, and centrality that reveal different aspects of how the network's nodes communicate. Here, we focus on a novel analysis of complex walks in a series of mammalian cortical networks that model potential dynamics of information flow between individual brain regions. We introduce two new measures called absorption and driftness. Absorption is the average length of random walks between any two nodes, and takes into account all paths that may diffuse activity throughout the network. Driftness is the ratio between absorption and the corresponding shortest path length. For a given node of the network, we also define four related measurements, namely in- and out-absorption as well as in- and out-driftness, as the averages of the corresponding measures from all nodes to that node, and from that node to all nodes, respectively. We find that the cat thalamo-cortical system incorporates features of two classic network topologies, Erdös–Rényi graphs with respect to in-absorption and in-driftness, and configuration models with respect to out-absorption and out-driftness. Moreover, taken together these four measures separate the network nodes based on broad functional roles (visual, auditory, somatomotor, and frontolimbic). PMID:21427794

  1. Biomechanics of Single Cortical Neurons

    PubMed Central

    Bernick, Kristin B.; Prevost, Thibault P.; Suresh, Subra; Socrate, Simona

    2011-01-01

    This study presents experimental results and computational analysis of the large strain dynamic behavior of single neurons in vitro with the objective of formulating a novel quantitative framework for the biomechanics of cortical neurons. Relying on the atomic force microscopy (AFM) technique, novel testing protocols are developed to enable the characterization of neural soma deformability over a range of indentation rates spanning three orders of magnitude – 10, 1, and 0.1 μm/s. Modified spherical AFM probes were utilized to compress the cell bodies of neonatal rat cortical neurons in load, unload, reload and relaxation conditions. The cell response showed marked hysteretic features, strong non-linearities, and substantial time/rate dependencies. The rheological data were complemented with geometrical measurements of cell body morphology, i.e. cross-diameter and height estimates. A constitutive model, validated by the present experiments, is proposed to quantify the mechanical behavior of cortical neurons. The model aimed to correlate empirical findings with measurable degrees of (hyper-) elastic resilience and viscosity at the cell level. The proposed formulation, predicated upon previous constitutive model developments undertaken at the cortical tissue level, was implemented into a three-dimensional finite element framework. The simulated cell response was calibrated to the experimental measurements under the selected test conditions, providing a novel single cell model that could form the basis for further refinements. PMID:20971217

  2. Subcortical orientation biases explain orientation selectivity of visual cortical cells

    PubMed Central

    Vidyasagar, Trichur R; Jayakumar, Jaikishan; Lloyd, Errol; Levichkina, Ekaterina V

    2015-01-01

    The primary visual cortex of carnivores and primates shows an orderly progression of domains of neurons that are selective to a particular orientation of visual stimuli such as bars and gratings. We recorded from single-thalamic afferent fibers that terminate in these domains to address the issue whether the orientation sensitivity of these fibers could form the basis of the remarkable orientation selectivity exhibited by most cortical cells. We first performed optical imaging of intrinsic signals to obtain a map of orientation domains on the dorsal aspect of the anaesthetized cat's area 17. After confirming using electrophysiological recordings the orientation preferences of single neurons within one or two domains in each animal, we pharmacologically silenced the cortex to leave only the afferent terminals active. The inactivation of cortical neurons was achieved by the superfusion of either kainic acid or muscimol. Responses of single geniculate afferents were then recorded by the use of high impedance electrodes. We found that the orientation preferences of the afferents matched closely with those of the cells in the orientation domains that they terminated in (Pearson's r = 0.633, n = 22, P = 0.002). This suggests a possible subcortical origin for cortical orientation selectivity. PMID:25855249

  3. Control of Somatosensory Cortical Processing by Thalamic Posterior Medial Nucleus: A New Role of Thalamus in Cortical Function

    PubMed Central

    Castejon, Carlos; Barros-Zulaica, Natali; Nuñez, Angel

    2016-01-01

    Current knowledge of thalamocortical interaction comes mainly from studying lemniscal thalamic systems. Less is known about paralemniscal thalamic nuclei function. In the vibrissae system, the posterior medial nucleus (POm) is the corresponding paralemniscal nucleus. POm neurons project to L1 and L5A of the primary somatosensory cortex (S1) in the rat brain. It is known that L1 modifies sensory-evoked responses through control of intracortical excitability suggesting that L1 exerts an influence on whisker responses. Therefore, thalamocortical pathways targeting L1 could modulate cortical firing. Here, using a combination of electrophysiology and pharmacology in vivo, we have sought to determine how POm influences cortical processing. In our experiments, single unit recordings performed in urethane-anesthetized rats showed that POm imposes precise control on the magnitude and duration of supra- and infragranular barrel cortex whisker responses. Our findings demonstrated that L1 inputs from POm imposed a time and intensity dependent regulation on cortical sensory processing. Moreover, we found that blocking L1 GABAergic inhibition or blocking P/Q-type Ca2+ channels in L1 prevents POm adjustment of whisker responses in the barrel cortex. Additionally, we found that POm was also controlling the sensory processing in S2 and this regulation was modulated by corticofugal activity from L5 in S1. Taken together, our data demonstrate the determinant role exerted by the POm in the adjustment of somatosensory cortical processing and in the regulation of cortical processing between S1 and S2. We propose that this adjustment could be a thalamocortical gain regulation mechanism also present in the processing of information between cortical areas. PMID:26820514

  4. Control of Somatosensory Cortical Processing by Thalamic Posterior Medial Nucleus: A New Role of Thalamus in Cortical Function.

    PubMed

    Castejon, Carlos; Barros-Zulaica, Natali; Nuñez, Angel

    2016-01-01

    Current knowledge of thalamocortical interaction comes mainly from studying lemniscal thalamic systems. Less is known about paralemniscal thalamic nuclei function. In the vibrissae system, the posterior medial nucleus (POm) is the corresponding paralemniscal nucleus. POm neurons project to L1 and L5A of the primary somatosensory cortex (S1) in the rat brain. It is known that L1 modifies sensory-evoked responses through control of intracortical excitability suggesting that L1 exerts an influence on whisker responses. Therefore, thalamocortical pathways targeting L1 could modulate cortical firing. Here, using a combination of electrophysiology and pharmacology in vivo, we have sought to determine how POm influences cortical processing. In our experiments, single unit recordings performed in urethane-anesthetized rats showed that POm imposes precise control on the magnitude and duration of supra- and infragranular barrel cortex whisker responses. Our findings demonstrated that L1 inputs from POm imposed a time and intensity dependent regulation on cortical sensory processing. Moreover, we found that blocking L1 GABAergic inhibition or blocking P/Q-type Ca2+ channels in L1 prevents POm adjustment of whisker responses in the barrel cortex. Additionally, we found that POm was also controlling the sensory processing in S2 and this regulation was modulated by corticofugal activity from L5 in S1. Taken together, our data demonstrate the determinant role exerted by the POm in the adjustment of somatosensory cortical processing and in the regulation of cortical processing between S1 and S2. We propose that this adjustment could be a thalamocortical gain regulation mechanism also present in the processing of information between cortical areas. PMID:26820514

  5. Environmental Enrichment Modulates Cortico-Cortical Interactions in the Mouse

    PubMed Central

    Chillemi, Santi; Maffei, Lamberto; Caleo, Matteo

    2011-01-01

    Environmental enrichment (EE) is an experimental protocol based on a complex sensorimotor stimulation that dramatically affects brain development. While it is widely believed that the effects of EE result from the unique combination of different sensory and motor stimuli, it is not known whether and how cortico-cortical interactions are shaped by EE. Since the primary visual cortex (V1) is one of the best characterized targets of EE, we looked for direct cortico-cortical projections impinging on V1, and we identified a direct monosynaptic connection between motor cortex and V1 in the mouse brain. To measure the interactions between these areas under standard and EE rearing conditions, we used simultaneous recordings of local field potentials (LFPs) in awake, freely moving animals. LFP signals were analyzed by using different methods of linear and nonlinear analysis of time series (cross-correlation, mutual information, phase synchronization). We found that EE decreases the level of coupling between the electrical activities of the two cortical regions with respect to the control group. From a functional point of view, our results indicate, for the first time, that an enhanced sensorimotor experience impacts on the brain by affecting the functional crosstalk between different cortical areas. PMID:21966482

  6. [Cortical responses evoked by vibrotactile sensations in deaf children].

    PubMed

    Quaranta, A; Cipriani, D; Mininni, F

    1980-05-30

    Vibrotactile evoked responses (VER) to 250 and 500 Hz presented respectively at 50 and 70 dB HL by BC vibrator placed on right thumb, were recorded in 20 children (10 with pathological EEG) with severe sensorineural hearing loss, or deaf since birth, both to control accuracy of cortical responses to high intensity auditory stimuli and to diagnose central non auditory pathways lesions. The results have shown that: VER are present in subjects with severe sensorineural hearing loss or deaf; in children with auditory lesions VER have parameters different from auditory evoked response (AER); VER recording is not related both to the presence of auditory lesions and to neurological pathology. PMID:7448007

  7. High-Degree Neurons Feed Cortical Computations.

    PubMed

    Timme, Nicholas M; Ito, Shinya; Myroshnychenko, Maxym; Nigam, Sunny; Shimono, Masanori; Yeh, Fang-Chin; Hottowy, Pawel; Litke, Alan M; Beggs, John M

    2016-05-01

    Recent work has shown that functional connectivity among cortical neurons is highly varied, with a small percentage of neurons having many more connections than others. Also, recent theoretical developments now make it possible to quantify how neurons modify information from the connections they receive. Therefore, it is now possible to investigate how information modification, or computation, depends on the number of connections a neuron receives (in-degree) or sends out (out-degree). To do this, we recorded the simultaneous spiking activity of hundreds of neurons in cortico-hippocampal slice cultures using a high-density 512-electrode array. This preparation and recording method combination produced large numbers of neurons recorded at temporal and spatial resolutions that are not currently available in any in vivo recording system. We utilized transfer entropy (a well-established method for detecting linear and nonlinear interactions in time series) and the partial information decomposition (a powerful, recently developed tool for dissecting multivariate information processing into distinct parts) to quantify computation between neurons where information flows converged. We found that computations did not occur equally in all neurons throughout the networks. Surprisingly, neurons that computed large amounts of information tended to receive connections from high out-degree neurons. However, the in-degree of a neuron was not related to the amount of information it computed. To gain insight into these findings, we developed a simple feedforward network model. We found that a degree-modified Hebbian wiring rule best reproduced the pattern of computation and degree correlation results seen in the real data. Interestingly, this rule also maximized signal propagation in the presence of network-wide correlations, suggesting a mechanism by which cortex could deal with common random background input. These are the first results to show that the extent to which a neuron

  8. High-Degree Neurons Feed Cortical Computations

    PubMed Central

    Timme, Nicholas M.; Ito, Shinya; Shimono, Masanori; Yeh, Fang-Chin; Litke, Alan M.; Beggs, John M.

    2016-01-01

    Recent work has shown that functional connectivity among cortical neurons is highly varied, with a small percentage of neurons having many more connections than others. Also, recent theoretical developments now make it possible to quantify how neurons modify information from the connections they receive. Therefore, it is now possible to investigate how information modification, or computation, depends on the number of connections a neuron receives (in-degree) or sends out (out-degree). To do this, we recorded the simultaneous spiking activity of hundreds of neurons in cortico-hippocampal slice cultures using a high-density 512-electrode array. This preparation and recording method combination produced large numbers of neurons recorded at temporal and spatial resolutions that are not currently available in any in vivo recording system. We utilized transfer entropy (a well-established method for detecting linear and nonlinear interactions in time series) and the partial information decomposition (a powerful, recently developed tool for dissecting multivariate information processing into distinct parts) to quantify computation between neurons where information flows converged. We found that computations did not occur equally in all neurons throughout the networks. Surprisingly, neurons that computed large amounts of information tended to receive connections from high out-degree neurons. However, the in-degree of a neuron was not related to the amount of information it computed. To gain insight into these findings, we developed a simple feedforward network model. We found that a degree-modified Hebbian wiring rule best reproduced the pattern of computation and degree correlation results seen in the real data. Interestingly, this rule also maximized signal propagation in the presence of network-wide correlations, suggesting a mechanism by which cortex could deal with common random background input. These are the first results to show that the extent to which a neuron

  9. Functional Calcium Imaging in Developing Cortical Networks

    PubMed Central

    Dawitz, Julia; Kroon, Tim; Hjorth, J.J. Johannes; Meredith, Rhiannon M.

    2011-01-01

    A hallmark pattern of activity in developing nervous systems is spontaneous, synchronized network activity. Synchronized activity has been observed in intact spinal cord, brainstem, retina, cortex and dissociated neuronal culture preparations. During periods of spontaneous activity, neurons depolarize to fire single or bursts of action potentials, activating many ion channels. Depolarization activates voltage-gated calcium channels on dendrites and spines that mediate calcium influx. Highly synchronized electrical activity has been measured from local neuronal networks using field electrodes. This technique enables high temporal sampling rates but lower spatial resolution due to integrated read-out of multiple neurons at one electrode. Single cell resolution of neuronal activity is possible using patch-clamp electrophysiology on single neurons to measure firing activity. However, the ability to measure from a network is limited to the number of neurons patched simultaneously, and typically is only one or two neurons. The use of calcium-dependent fluorescent indicator dyes has enabled the measurement of synchronized activity across a network of cells. This technique gives both high spatial resolution and sufficient temporal sampling to record spontaneous activity of the developing network. A key feature of newly-forming cortical and hippocampal networks during pre- and early postnatal development is spontaneous, synchronized neuronal activity (Katz & Shatz, 1996; Khaziphov & Luhmann, 2006). This correlated network activity is believed to be essential for the generation of functional circuits in the developing nervous system (Spitzer, 2006). In both primate and rodent brain, early electrical and calcium network waves are observed pre- and postnatally in vivo and in vitro (Adelsberger et al., 2005; Garaschuk et al., 2000; Lamblin et al., 1999). These early activity patterns, which are known to control several developmental processes including neuronal differentiation

  10. Cortical Visual Impairment: New Directions

    PubMed Central

    Good, William V.

    2009-01-01

    Cortical visual impairment is the leading cause of bilateral low vision in children in the U.S., yet very little research is being done to find new diagnostic measures and treatments. Dr. Velma Dobson's pioneering work on visual assessments of developmentally delayed children stands out as highly significant in this field. Future research will assess new diagnostic measures, including advanced imaging techniques. In addition, research will evaluate methods to prevent, treat, and rehabilitate infants and children afflicted with this condition. PMID:19417710

  11. A simulated actuator driven by motor cortical signals.

    PubMed

    Lukashin, A V; Amirikian, B R; Georgopoulos, A P

    1996-11-01

    One problem in motor control concerns the mechanism whereby the central nervous system translates the motor cortical command encoded in cell activity into a coordinated contraction of limb muscles to generate a desired motor output. This problem is closely related to the design of adaptive systems that transform neuronal signals chronically recorded from the motor cortex into the physiologically appropriate motor output of multijoint prosthetic limbs. In this study we demonstrated how this transformation can be carried out by an artificial neural network using as command signals the actual impulse activity obtained from recordings in the motor cortex of monkeys during the performance of a task that required the exertion of force in different directions. The network receives experimentally measured brain signals and recodes them into motor actions of a simulated actuator that mimics the primate arm. The actuator responds to the motor cortical commands with surprising fidelity, generating forces in close quantitative agreement with those exerted by trained monkeys, in both the temporal and spatial domains. Moreover, we show that the time-varying motor output may be controlled by the impulse activity of as few as 15 motor cortical cells. These results outline a potentially implementable computation scheme that utilizes raw neuronal signals to drive artificial mechanical systems. PMID:8981430

  12. Identifying True Cortical Interactions in MEG using the Nulling Beamformer

    PubMed Central

    Hui, Hua Brian; Pantazis, Dimitrios; Bressler, Steven L.; Leahy, Richard M.

    2009-01-01

    Modeling functional brain interaction networks using non-invasive EEG and MEG data is more challenging than using intracranial recording data. This is because most interaction measures are not robust to the cross-talk (interference) between cortical regions, which may arise due to the limited spatial resolution of EEG/MEG inverse procedures. In this paper we describe a modified beam-forming approach to accurately measure cortical interactions from EEG/MEG data, designed to suppress cross-talk between cortical regions. We estimate interaction measures from the output of the modified beamformer and test for statistical significance using permutation tests. Since the underlying neuronal sources and their interactions are unknown in real MEG data, we demonstrate the performance of the proposed beamforming method in a novel simulation scheme, where intracranial recordings from a macaque monkey are used as neural sources to simulate realistic MEG signals. The advantage of this approach is that local field potentials are more realistic representations of true neuronal sources than simulation models and therefore are more suitable to indicate the performance of our nulling beamforming method. PMID:19896541

  13. Distinct and Overlapping Cortical Areas for Bilingual Naming and Reading using Cortical Stimulation– Case Report

    PubMed Central

    Serafini, Sandra; Gururangan, Sridharan; Friedman, Allan; Haglund, Michael

    2009-01-01

    A bilingual pediatric patient treated for tumor resection was mapped extraoperatively with cortical stimulation to preserve English and Hebrew languages. The authors mapped both languages by using four tasks: 1) English visual naming, 2) Hebrew visual naming, 3) read English/respond Hebrew, 4) Hebrew reading. Essential sites for primary (L1) and secondary (L2) languages were compared, photographically recorded, and plotted onto a schematic brain of the patient. Three types of sites were found in this patient: 1) Multi-use sites (both languages, multiple tasks) in frontal, temporal, and parietal areas, 2) Single-task sites (one task, both languages) in post-central and parietal areas, and 3) Single-use sites (one task, one language) in frontal, temporal, and parietal areas. These results lend support to the concept that bilinguals can have distinct cortical representation both of different languages and of different language tasks in addition to overlapping or shared sites that support both languages and multiple tasks. PMID:18352772

  14. Brief anesthesia, but not voluntary locomotion, significantly alters cortical temperature

    PubMed Central

    Shirey, Michael J.; Kudlik, D'Anne E.; Huo, Bing-Xing; Greene, Stephanie E.; Drew, Patrick J.

    2015-01-01

    Changes in brain temperature can alter electrical properties of neurons and cause changes in behavior. However, it is not well understood how behaviors, like locomotion, or experimental manipulations, like anesthesia, alter brain temperature. We implanted thermocouples in sensorimotor cortex of mice to understand how cortical temperature was affected by locomotion, as well as by brief and prolonged anesthesia. Voluntary locomotion induced small (∼0.1°C) but reliable increases in cortical temperature that could be described using a linear convolution model. In contrast, brief (90-s) exposure to isoflurane anesthesia depressed cortical temperature by ∼2°C, which lasted for up to 30 min after the cessation of anesthesia. Cortical temperature decreases were not accompanied by a concomitant decrease in the γ-band local field potential power, multiunit firing rate, or locomotion behavior, which all returned to baseline within a few minutes after the cessation of anesthesia. In anesthetized animals where core body temperature was kept constant, cortical temperature was still >1°C lower than in the awake animal. Thermocouples implanted in the subcortex showed similar temperature changes under anesthesia, suggesting these responses occur throughout the brain. Two-photon microscopy of individual blood vessel dynamics following brief isoflurane exposure revealed a large increase in vessel diameter that ceased before the brain temperature significantly decreased, indicating cerebral heat loss was not due to increased cerebral blood vessel dilation. These data should be considered in experimental designs recording in anesthetized preparations, computational models relating temperature and neural activity, and awake-behaving methods that require brief anesthesia before experimental procedures. PMID:25972579

  15. Electroencephalographic coherence and cortical acetylcholine during ketamine-induced unconsciousness

    PubMed Central

    Pal, D.; Hambrecht-Wiedbusch, V. S.; Silverstein, B. H.; Mashour, G. A.

    2015-01-01

    Background There is limited understanding of cortical neurochemistry and cortical connectivity during ketamine anaesthesia. We conducted a systematic study to investigate the effects of ketamine on cortical acetylcholine (ACh) and electroencephalographic coherence. Methods Male Sprague–Dawley rats (n=11) were implanted with electrodes to record electroencephalogram (EEG) from frontal, parietal, and occipital cortices, and with a microdialysis guide cannula for simultaneous measurement of ACh concentrations in prefrontal cortex before, during, and after ketamine anaesthesia. Coherence and power spectral density computed from the EEG, and ACh concentrations, were compared between conscious and unconscious states. Loss of righting reflex was used as a surrogate for unconsciousness. Results Ketamine-induced unconsciousness was associated with a global reduction of power (P=0.02) in higher gamma bandwidths (>65 Hz), a global reduction of coherence (P≤0.01) across a broad frequency range (0.5–250 Hz), and a significant increase in ACh concentrations (P=0.01) in the prefrontal cortex. Compared with the unconscious state, recovery of righting reflex was marked by a further increase in ACh concentrations (P=0.0007), global increases in power in theta (4–10 Hz; P=0.03) and low gamma frequencies (25–55 Hz; P=0.0001), and increase in power (P≤0.01) and coherence (P≤0.002) in higher gamma frequencies (65–250 Hz). Acetylcholine concentrations, coherence, and spectral properties returned to baseline levels after a prolonged recovery period. Conclusions Ketamine-induced unconsciousness is characterized by suppression of high-frequency gamma activity and a breakdown of cortical coherence, despite increased cholinergic tone in the cortex. PMID:25951831

  16. Giant early components of somatosensory evoked potentials to tibial nerve stimulation in cortical myoclonus.

    PubMed

    Anzellotti, Francesca; Onofrj, Marco; Bonanni, Laura; Saracino, Antonio; Franciotti, Raffaella

    2016-01-01

    Enlarged cortical components of somatosensory evoked potentials (giant SEPs) recorded by electroencephalography (EEG) and abnormal somatosensory evoked magnetic fields (SEFs) recorded by magnetoencephalography (MEG) are observed in the majority of patients with cortical myoclonus (CM). Studies on simultaneous recordings of SEPs and SEFs showed that generator mechanism of giant SEPs involves both primary sensory and motor cortices. However the generator sources of giant SEPs have not been fully understood as only one report describes clearly giant SEPs following lower limb stimulation. In our study we performed a combined EEG-MEG recording on responses elicited by electric median and tibial nerve stimulation in a patient who developed consequently to methyl bromide intoxication CM with giant SEPs to median and tibial nerve stimuli. SEPs wave shapes were identified on the basis of polarity-latency components (e.g. P15-N20-P25) as defined by earlier studies and guidelines. At EEG recording, the SEP giant component did not appear in the latency range of the first cortical component for median nerve SEP (N20), but appeared instead in the range of the P37 tibial nerve SEP, which is currently identified as the first cortical component elicited by tibial nerve stimuli. Our MEG and EEG SEPs recordings also showed that components in the latency range of P37 were preceded by other cortical components. These findings suggest that lower limb P37 does not correspond to upper limb N20. MEG results confirmed that giant SEFs are the second component from both tibial (N43m-P43m) and median (N27m-P27m) nerve stimulation. MEG dipolar sources of these giant components were located in the primary sensory and motor area. PMID:27489768

  17. Mapping dynamical properties of cortical microcircuits using robotized TMS and EEG: Towards functional cytoarchitectonics.

    PubMed

    Harquel, Sylvain; Bacle, Thibault; Beynel, Lysianne; Marendaz, Christian; Chauvin, Alan; David, Olivier

    2016-07-15

    Brain dynamics at rest depend on the large-scale interactions between oscillating cortical microcircuits arranged into macrocolumns. Cytoarchitectonic studies have shown that the structure of those microcircuits differs between cortical regions, but very little is known about interregional differences of their intrinsic dynamics at a macro-scale in human. We developed here a new method aiming at mapping the dynamical properties of cortical microcircuits non-invasively using the coupling between robotized transcranial magnetic stimulation and electroencephalography. We recorded the responses evoked by the stimulation of 18 cortical targets largely covering the accessible neocortex in 22 healthy volunteers. Specific data processing methods were developed to map the local source activity of each cortical target, which showed inter-regional differences with very good interhemispheric reproducibility. Functional signatures of cortical microcircuits were further studied using spatio-temporal decomposition of local source activities in order to highlight principal brain modes. The identified brain modes revealed that cortical areas with similar intrinsic dynamical properties could be distributed either locally or not, with a spatial signature that was somewhat reminiscent of resting state networks. Our results provide the proof of concept of "functional cytoarchitectonics", that would guide the parcellation of the human cortex using not only its cytoarchitecture but also its intrinsic responses to local perturbations. This opens new avenues for brain modelling and physiopathology readouts. PMID:27153976

  18. Traumatic Brain Injury Increases Cortical Glutamate Network Activity by Compromising GABAergic Control

    PubMed Central

    Cantu, David; Walker, Kendall; Andresen, Lauren; Taylor-Weiner, Amaro; Hampton, David; Tesco, Giuseppina; Dulla, Chris G.

    2015-01-01

    Traumatic brain injury (TBI) is a major risk factor for developing pharmaco-resistant epilepsy. Although disruptions in brain circuitry are associated with TBI, the precise mechanisms by which brain injury leads to epileptiform network activity is unknown. Using controlled cortical impact (CCI) as a model of TBI, we examined how cortical excitability and glutamatergic signaling was altered following injury. We optically mapped cortical glutamate signaling using FRET-based glutamate biosensors, while simultaneously recording cortical field potentials in acute brain slices 2–4 weeks following CCI. Cortical electrical stimulation evoked polyphasic, epileptiform field potentials and disrupted the input–output relationship in deep layers of CCI-injured cortex. High-speed glutamate biosensor imaging showed that glutamate signaling was significantly increased in the injured cortex. Elevated glutamate responses correlated with epileptiform activity, were highest directly adjacent to the injury, and spread via deep cortical layers. Immunoreactivity for markers of GABAergic interneurons were significantly decreased throughout CCI cortex. Lastly, spontaneous inhibitory postsynaptic current frequency decreased and spontaneous excitatory postsynaptic current increased after CCI injury. Our results suggest that specific cortical neuronal microcircuits may initiate and facilitate the spread of epileptiform activity following TBI. Increased glutamatergic signaling due to loss of GABAergic control may provide a mechanism by which TBI can give rise to post-traumatic epilepsy. PMID:24610117

  19. Human Thalamus Regulates Cortical Activity via Spatially Specific and Structurally Constrained Phase-Amplitude Coupling

    PubMed Central

    Malekmohammadi, Mahsa; Elias, W. Jeff; Pouratian, Nader

    2015-01-01

    Although the thalamus is believed to regulate and coordinate cortical activity both within and across functional regions, such as motor and visual cortices, direct evidence for such regulation and the mechanism of regulation remains poorly described. Using simultaneous invasive recordings of cortical and thalamic electrophysiological activity in 2 awake and spontaneously behaving human subjects, we provide direct evidence of thalamic regulation of cortical activity through a mechanism of phase-amplitude coupling (PAC), in which the phase of low frequency oscillations regulates the amplitude of higher frequency oscillations. Specifically, we show that cortical PAC between the theta phase and beta amplitude is spatially dependent on and time variant with the magnitude of thalamocortical theta coherence. Moreover, using causality analysis and MR diffusion tractography, we provide evidence that thalamic theta activity drives cortical theta oscillations and PAC across structures and that these thalamocortical relationships are structurally constrained by anatomic pathways. This relationship allows for new evidence of thalamocortical PAC. Given the diffuse connectivity of the thalamus with the cerebral cortex, thalamocortical PAC may play an important role in addressing the binding problem, including both integration and segregation of information within and across cortical areas. PMID:24408958

  20. Prognostic value of cortical magnetic stimulation in spinal cord injury.

    PubMed

    Clarke, C E; Modarres-Sadeghi, H; Twomey, J A; Burt, A A

    1994-08-01

    Cortical magnetic stimulation was performed in a consecutive series of 10 patients presenting within 15 days of traumatic spinal cord injury. In those patients with complete paraplegia or quadriplegia, motor evoked potentials at presentation were absent below the level of the lesion. Six months after the injury, potentials had returned in the biceps brachii and abductor pollicis brevis muscles in some quadriplegic cases, but remained absent from the tibialis anterior in all of this group. None of those with a complete lesion made a significant functional recovery. Of the three patients with incomplete quadriplegia, two showed a significant recovery after 6 months. Motor evoked potentials were recordable below the level of the lesion at presentation in these cases, although the latencies were prolonged. In the remaining patient who failed to improve, potentials were unrecordable throughout the study. This small pilot study suggests that cortical magnetic stimulation may be useful in refining the prognosis in patients with an incomplete spinal cord injury. PMID:7970860

  1. Population based models of cortical drug response: insights from anaesthesia

    PubMed Central

    Bojak, Ingo; Liley, David T. J.

    2008-01-01

    A great explanatory gap lies between the molecular pharmacology of psychoactive agents and the neurophysiological changes they induce, as recorded by neuroimaging modalities. Causally relating the cellular actions of psychoactive compounds to their influence on population activity is experimentally challenging. Recent developments in the dynamical modelling of neural tissue have attempted to span this explanatory gap between microscopic targets and their macroscopic neurophysiological effects via a range of biologically plausible dynamical models of cortical tissue. Such theoretical models allow exploration of neural dynamics, in particular their modification by drug action. The ability to theoretically bridge scales is due to a biologically plausible averaging of cortical tissue properties. In the resulting macroscopic neural field, individual neurons need not be explicitly represented (as in neural networks). The following paper aims to provide a non-technical introduction to the mean field population modelling of drug action and its recent successes in modelling anaesthesia. PMID:19003456

  2. Cortical Signals for Rewarded Actions and Strategic Exploration

    PubMed Central

    Donahue, Christopher H.; Seo, Hyojung; Lee, Daeyeol

    2013-01-01

    SUMMARY In stable environments, decision makers can exploit their previously learned strategies for optimal outcomes, while exploration might lead to better options in unstable environments. Here, to investigate the cortical contributions to exploratory behavior, we analyzed singleneuron activity recorded from 4 different cortical areas of monkeys performing a matching pennies task and a visual search task, which encouraged and discouraged exploration, respectively. We found that neurons in multiple regions in the frontal and parietal cortex tended to encode signals related to previously rewarded actions more reliably than unrewarded actions. In addition, signals for rewarded choices in the supplementary eye field were attenuated during the visual search task, and were correlated with the tendency to switch choices during the matching pennies task. These results suggest that the supplementary eye field might play a unique role in encouraging animals to explore alternative decision-making strategies. PMID:24012280

  3. Influence of spiking activity on cortical local field potentials

    PubMed Central

    Waldert, Stephan; Lemon, Roger N; Kraskov, Alexander

    2013-01-01

    The intra-cortical local field potential (LFP) reflects a variety of electrophysiological processes including synaptic inputs to neurons and their spiking activity. It is still a common assumption that removing high frequencies, often above 300 Hz, is sufficient to exclude spiking activity from LFP activity prior to analysis. Conclusions based on such supposedly spike-free LFPs can result in false interpretations of neurophysiological processes and erroneous correlations between LFPs and behaviour or spiking activity. Such findings might simply arise from spike contamination rather than from genuine changes in synaptic input activity. Although the subject of recent studies, the extent of LFP contamination by spikes is unclear, and the fundamental problem remains. Using spikes recorded in the motor cortex of the awake monkey, we investigated how different factors, including spike amplitude, duration and firing rate, together with the noise statistic, can determine the extent to which spikes contaminate intra-cortical LFPs. We demonstrate that such contamination is realistic for LFPs with a frequency down to ∼10 Hz. For LFP activity below ∼10 Hz, such as movement-related potential, contamination is theoretically possible but unlikely in real situations. Importantly, LFP frequencies up to the (high-) gamma band can remain unaffected. This study shows that spike–LFP crosstalk in intra-cortical recordings should be assessed for each individual dataset to ensure that conclusions based on LFP analysis are valid. To this end, we introduce a method to detect and to visualise spike contamination, and provide a systematic guide to assess spike contamination of intra-cortical LFPs. PMID:23981719

  4. Subdural electrode recording of generalized photoepileptic responses

    PubMed Central

    Mukundan, L.; Lie, O.V.; Leary, L.D.; Papanastassiou, A.M.; Morgan, L.C.; Szabó, C.Á.

    2014-01-01

    We evaluated the spatiotemporal distribution of photic driving (PDR), photoparoxysmal (PPR), and photoconvulsive (PCR) responses recorded by intracranial electrodes (ic-EEG) in a patient with generalized photosensitivity and right frontal lobe cortical dysplasia. Intermittent light stimulation (ILS) was performed thirteen times in nine days. Cortical responses to ILS recorded by ic-EEG were reviewed and classified as PDRs, PPRs, and PCRs. Photic driving responses were restricted to the occipital lobe at ILS frequencies below 9 Hz, spreading to the parietal and central regions at > 9 Hz. Photoparoxysmal responses commonly presented as focal, medial occipital, and parietal interictal epileptic discharges (IEDs), the latter propagating to the sensorimotor cortices. Generalized IEDs were also generated in the setting of PPRs. Photoconvulsive responses, characterized by repetitive bilateral upper extremity myoclonus sustained until the end of the stimulus, were associated with propagation of the medial parieto-occipital discharge to the primary sensorimotor and supplementary area cortices, while generalized myoclonic seizures were associated with a generalized spike-and-wave discharge with an interhemispheric posterior cingulate onset sparing the sensorimotor cortices. Both types of PCR could occur during the same stimulus. Regardless of the pathway, PCRs only occurred when PDRs involved the parietal cortices. While there may be more than one pathway underlying PCRs, parietal lobe association cortices appear to be critical to their generation. PMID:25737962

  5. Circadian regulation of human cortical excitability.

    PubMed

    Ly, Julien Q M; Gaggioni, Giulia; Chellappa, Sarah L; Papachilleos, Soterios; Brzozowski, Alexandre; Borsu, Chloé; Rosanova, Mario; Sarasso, Simone; Middleton, Benita; Luxen, André; Archer, Simon N; Phillips, Christophe; Dijk, Derk-Jan; Maquet, Pierre; Massimini, Marcello; Vandewalle, Gilles

    2016-01-01

    Prolonged wakefulness alters cortical excitability, which is essential for proper brain function and cognition. However, besides prior wakefulness, brain function and cognition are also affected by circadian rhythmicity. Whether the regulation of cognition involves a circadian impact on cortical excitability is unknown. Here, we assessed cortical excitability from scalp electroencephalography (EEG) responses to transcranial magnetic stimulation in 22 participants during 29 h of wakefulness under constant conditions. Data reveal robust circadian dynamics of cortical excitability that are strongest in those individuals with highest endocrine markers of circadian amplitude. In addition, the time course of cortical excitability correlates with changes in EEG synchronization and cognitive performance. These results demonstrate that the crucial factor for cortical excitability, and basic brain function in general, is the balance between circadian rhythmicity and sleep need, rather than sleep homoeostasis alone. These findings have implications for clinical applications such as non-invasive brain stimulation in neurorehabilitation. PMID:27339884

  6. Circadian regulation of human cortical excitability

    PubMed Central

    Ly, Julien Q. M.; Gaggioni, Giulia; Chellappa, Sarah L.; Papachilleos, Soterios; Brzozowski, Alexandre; Borsu, Chloé; Rosanova, Mario; Sarasso, Simone; Middleton, Benita; Luxen, André; Archer, Simon N.; Phillips, Christophe; Dijk, Derk-Jan; Maquet, Pierre; Massimini, Marcello; Vandewalle, Gilles

    2016-01-01

    Prolonged wakefulness alters cortical excitability, which is essential for proper brain function and cognition. However, besides prior wakefulness, brain function and cognition are also affected by circadian rhythmicity. Whether the regulation of cognition involves a circadian impact on cortical excitability is unknown. Here, we assessed cortical excitability from scalp electroencephalography (EEG) responses to transcranial magnetic stimulation in 22 participants during 29 h of wakefulness under constant conditions. Data reveal robust circadian dynamics of cortical excitability that are strongest in those individuals with highest endocrine markers of circadian amplitude. In addition, the time course of cortical excitability correlates with changes in EEG synchronization and cognitive performance. These results demonstrate that the crucial factor for cortical excitability, and basic brain function in general, is the balance between circadian rhythmicity and sleep need, rather than sleep homoeostasis alone. These findings have implications for clinical applications such as non-invasive brain stimulation in neurorehabilitation. PMID:27339884

  7. Hamilton-Jacobi skeleton on cortical surfaces.

    PubMed

    Shi, Y; Thompson, P M; Dinov, I; Toga, A W

    2008-05-01

    In this paper, we propose a new method to construct graphical representations of cortical folding patterns by computing skeletons on triangulated cortical surfaces. In our approach, a cortical surface is first partitioned into sulcal and gyral regions via the solution of a variational problem using graph cuts, which can guarantee global optimality. After that, we extend the method of Hamilton-Jacobi skeleton [1] to subsets of triangulated surfaces, together with a geometrically intuitive pruning process that can trade off between skeleton complexity and the completeness of representing folding patterns. Compared with previous work that uses skeletons of 3-D volumes to represent sulcal patterns, the skeletons on cortical surfaces can be easily decomposed into branches and provide a simpler way to construct graphical representations of cortical morphometry. In our experiments, we demonstrate our method on two different cortical surface models, its ability of capturing major sulcal patterns and its application to compute skeletons of gyral regions. PMID:18450539

  8. Cortical Tremor (CT) with coincident orthostatic movements.

    PubMed

    Termsarasab, Pichet; Frucht, Steven J

    2015-01-01

    Cortical tremor (CT) is a form of cortical reflex myoclonus that can mimic essential tremor (ET). Clinical features that are helpful in distinguishing CT from ET are the irregular and jerky appearance of the movements. We report two patients with CT with coexisting orthostatic movements, either orthostatic tremor (OT) or myoclonus, who experienced functional improvement in both cortical myoclonus and orthostatic movements when treated with levetiracetam. PMID:26788343

  9. Communication and wiring in the cortical connectome

    PubMed Central

    Budd, Julian M. L.; Kisvárday, Zoltán F.

    2012-01-01

    In cerebral cortex, the huge mass of axonal wiring that carries information between near and distant neurons is thought to provide the neural substrate for cognitive and perceptual function. The goal of mapping the connectivity of cortical axons at different spatial scales, the cortical connectome, is to trace the paths of information flow in cerebral cortex. To appreciate the relationship between the connectome and cortical function, we need to discover the nature and purpose of the wiring principles underlying cortical connectivity. A popular explanation has been that axonal length is strictly minimized both within and between cortical regions. In contrast, we have hypothesized the existence of a multi-scale principle of cortical wiring where to optimize communication there is a trade-off between spatial (construction) and temporal (routing) costs. Here, using recent evidence concerning cortical spatial networks we critically evaluate this hypothesis at neuron, local circuit, and pathway scales. We report three main conclusions. First, the axonal and dendritic arbor morphology of single neocortical neurons may be governed by a similar wiring principle, one that balances the conservation of cellular material and conduction delay. Second, the same principle may be observed for fiber tracts connecting cortical regions. Third, the absence of sufficient local circuit data currently prohibits any meaningful assessment of the hypothesis at this scale of cortical organization. To avoid neglecting neuron and microcircuit levels of cortical organization, the connectome framework should incorporate more morphological description. In addition, structural analyses of temporal cost for cortical circuits should take account of both axonal conduction and neuronal integration delays, which appear mostly of the same order of magnitude. We conclude the hypothesized trade-off between spatial and temporal costs may potentially offer a powerful explanation for cortical wiring patterns

  10. Photophobia and cortical visual impairment.

    PubMed

    Jan, J E; Groenveld, M; Anderson, D P

    1993-06-01

    Photophobia, or intolerance of light, is not completely understood as a symptom. It has been divided into ocular and central types. This study shows that persistent, usually mild, photophobia occurs in about one-third of children with cortical visual impairment (CVI). When the CVI is congenital the photophobia is present from birth, and when it is acquired the sensitivity to light appears immediately after the brain insult. The intensity of photophobia tends to diminish with time and occasionally it may even disappear. The pathophysiology is unclear, as in all other neurological disorders associated with photophobia. PMID:8504889

  11. Cortical auditory disorders: clinical and psychoacoustic features.

    PubMed Central

    Mendez, M F; Geehan, G R

    1988-01-01

    The symptoms of two patients with bilateral cortical auditory lesions evolved from cortical deafness to other auditory syndromes: generalised auditory agnosia, amusia and/or pure word deafness, and a residual impairment of temporal sequencing. On investigation, both had dysacusis, absent middle latency evoked responses, acoustic errors in sound recognition and matching, inconsistent auditory behaviours, and similarly disturbed psychoacoustic discrimination tasks. These findings indicate that the different clinical syndromes caused by cortical auditory lesions form a spectrum of related auditory processing disorders. Differences between syndromes may depend on the degree of involvement of a primary cortical processing system, the more diffuse accessory system, and possibly the efferent auditory system. Images PMID:2450968

  12. Rich-Club Organization in Effective Connectivity among Cortical Neurons.

    PubMed

    Nigam, Sunny; Shimono, Masanori; Ito, Shinya; Yeh, Fang-Chin; Timme, Nicholas; Myroshnychenko, Maxym; Lapish, Christopher C; Tosi, Zachary; Hottowy, Pawel; Smith, Wesley C; Masmanidis, Sotiris C; Litke, Alan M; Sporns, Olaf; Beggs, John M

    2016-01-20

    The performance of complex networks, like the brain, depends on how effectively their elements communicate. Despite the importance of communication, it is virtually unknown how information is transferred in local cortical networks, consisting of hundreds of closely spaced neurons. To address this, it is important to record simultaneously from hundreds of neurons at a spacing that matches typical axonal connection distances, and at a temporal resolution that matches synaptic delays. We used a 512-electrode array (60 μm spacing) to record spontaneous activity at 20 kHz from up to 500 neurons simultaneously in slice cultures of mouse somatosensory cortex for 1 h at a time. We applied a previously validated version of transfer entropy to quantify information transfer. Similar to in vivo reports, we found an approximately lognormal distribution of firing rates. Pairwise information transfer strengths also were nearly lognormally distributed, similar to reports of synaptic strengths. Some neurons transferred and received much more information than others, which is consistent with previous predictions. Neurons with the highest outgoing and incoming information transfer were more strongly connected to each other than chance, thus forming a "rich club." We found similar results in networks recorded in vivo from rodent cortex, suggesting the generality of these findings. A rich-club structure has been found previously in large-scale human brain networks and is thought to facilitate communication between cortical regions. The discovery of a small, but information-rich, subset of neurons within cortical regions suggests that this population will play a vital role in communication, learning, and memory. Significance statement: Many studies have focused on communication networks between cortical brain regions. In contrast, very few studies have examined communication networks within a cortical region. This is the first study to combine such a large number of neurons (several

  13. Rich-Club Organization in Effective Connectivity among Cortical Neurons

    PubMed Central

    Shimono, Masanori; Ito, Shinya; Yeh, Fang-Chin; Timme, Nicholas; Myroshnychenko, Maxym; Lapish, Christopher C.; Tosi, Zachary; Hottowy, Pawel; Smith, Wesley C.; Masmanidis, Sotiris C.; Litke, Alan M.; Sporns, Olaf; Beggs, John M.

    2016-01-01

    The performance of complex networks, like the brain, depends on how effectively their elements communicate. Despite the importance of communication, it is virtually unknown how information is transferred in local cortical networks, consisting of hundreds of closely spaced neurons. To address this, it is important to record simultaneously from hundreds of neurons at a spacing that matches typical axonal connection distances, and at a temporal resolution that matches synaptic delays. We used a 512-electrode array (60 μm spacing) to record spontaneous activity at 20 kHz from up to 500 neurons simultaneously in slice cultures of mouse somatosensory cortex for 1 h at a time. We applied a previously validated version of transfer entropy to quantify information transfer. Similar to in vivo reports, we found an approximately lognormal distribution of firing rates. Pairwise information transfer strengths also were nearly lognormally distributed, similar to reports of synaptic strengths. Some neurons transferred and received much more information than others, which is consistent with previous predictions. Neurons with the highest outgoing and incoming information transfer were more strongly connected to each other than chance, thus forming a “rich club.” We found similar results in networks recorded in vivo from rodent cortex, suggesting the generality of these findings. A rich-club structure has been found previously in large-scale human brain networks and is thought to facilitate communication between cortical regions. The discovery of a small, but information-rich, subset of neurons within cortical regions suggests that this population will play a vital role in communication, learning, and memory. SIGNIFICANCE STATEMENT Many studies have focused on communication networks between cortical brain regions. In contrast, very few studies have examined communication networks within a cortical region. This is the first study to combine such a large number of neurons (several

  14. Linking contemporary high resolution magnetic resonance imaging to the von Economo legacy: A study on the comparison of MRI cortical thickness and histological measurements of cortical structure.

    PubMed

    Scholtens, Lianne H; de Reus, Marcel A; van den Heuvel, Martijn P

    2015-08-01

    The cerebral cortex is a distinctive part of the mammalian nervous system, displaying a spatial variety in cyto-, chemico-, and myelinoarchitecture. As part of a rich history of histological findings, pioneering anatomists von Economo and Koskinas provided detailed mappings on the cellular structure of the human cortex, reporting on quantitative aspects of cytoarchitecture of cortical areas. Current day investigations into the structure of human cortex have embraced technological advances in Magnetic Resonance Imaging (MRI) to assess macroscale thickness and organization of the cortical mantle in vivo. However, direct comparisons between current day MRI estimates and the quantitative measurements of early anatomists have been limited. Here, we report on a simple, but nevertheless important cross-analysis between the histological reports of von Economo and Koskinas on variation in thickness of the cortical mantle and MRI derived measurements of cortical thickness. We translated the von Economo cortical atlas to a subdivision of the commonly used Desikan-Killiany atlas (as part of the FreeSurfer Software package and a commonly used parcellation atlas in studies examining MRI cortical thickness). Next, values of "width of the cortical mantle" as provided by the measurements of von Economo and Koskinas were correlated to cortical thickness measurements derived from high-resolution anatomical MRI T1 data of 200+ subjects of the Human Connectome Project (HCP). Cross-correlation revealed a significant association between group-averaged MRI measurements of cortical thickness and histological recordings (r = 0.54, P < 0.001). Further validating such a correlation, we manually segmented the von Economo parcellation atlas on the standardized Colin27 brain dataset and applied the obtained three-dimensional von Economo segmentation atlas to the T1 data of each of the HCP subjects. Highly consistent with our findings for the mapping to the Desikan-Killiany regions, cross

  15. Evaluation of Mental Index, Mandibular Cortical Index and Panoramic Mandibular Index on Dental Panoramic Radiographs in the Elderly

    PubMed Central

    Hastar, Esin; Yilmaz, H. Huseyin; Orhan, Hikmet

    2011-01-01

    Objectives: The aims of this study were to evaluate the influence of gender and dental status on the mental index, mandibular cortical index and panoramic mandibular index from dental panoramic radiographs in elderly who had osteoporosis or did not have osteoporosis. Methods: Panoramic radiographs of 487 elderly dental patients (age range 60–88 years) were evaluated. It were recorded osteoporotic status according to the patients’ medical anamnesis and values of the mandibular cortical index (MCI), panoramic mandibular index (PMI), mandibular cortical width (MCW) Results: Dental status was statistically significantly associated with the mandibular cortical width, panoramic mandibular index and the categories of MCI (P<.05). There were statistically different mandibular cortical width and panoramic mandibular index values in patients with osteoporosis and without osteoporosis (P<.05) Conclusions: Our study showed that there were statistically significant differences according to gender, dental status, and values of the MCW, MCI and PMI between patients with and those without osteoporosis. PMID:21228957

  16. Cortical control of facial expression.

    PubMed

    Müri, René M

    2016-06-01

    The present Review deals with the motor control of facial expressions in humans. Facial expressions are a central part of human communication. Emotional face expressions have a crucial role in human nonverbal behavior, allowing a rapid transfer of information between individuals. Facial expressions can be either voluntarily or emotionally controlled. Recent studies in nonhuman primates and humans have revealed that the motor control of facial expressions has a distributed neural representation. At least five cortical regions on the medial and lateral aspects of each hemisphere are involved: the primary motor cortex, the ventral lateral premotor cortex, the supplementary motor area on the medial wall, and the rostral and caudal cingulate cortex. The results of studies in humans and nonhuman primates suggest that the innervation of the face is bilaterally controlled for the upper part and mainly contralaterally controlled for the lower part. Furthermore, the primary motor cortex, the ventral lateral premotor cortex, and the supplementary motor area are essential for the voluntary control of facial expressions. In contrast, the cingulate cortical areas are important for emotional expression, because they receive input from different structures of the limbic system. PMID:26418049

  17. Gyrification from constrained cortical expansion

    PubMed Central

    Tallinen, Tuomas; Chung, Jun Young; Biggins, John S.; Mahadevan, L.

    2014-01-01

    The exterior of the mammalian brain—the cerebral cortex—has a conserved layered structure whose thickness varies little across species. However, selection pressures over evolutionary time scales have led to cortices that have a large surface area to volume ratio in some organisms, with the result that the brain is strongly convoluted into sulci and gyri. Here we show that the gyrification can arise as a nonlinear consequence of a simple mechanical instability driven by tangential expansion of the gray matter constrained by the white matter. A physical mimic of the process using a layered swelling gel captures the essence of the mechanism, and numerical simulations of the brain treated as a soft solid lead to the formation of cusped sulci and smooth gyri similar to those in the brain. The resulting gyrification patterns are a function of relative cortical expansion and relative thickness (compared with brain size), and are consistent with observations of a wide range of brains, ranging from smooth to highly convoluted. Furthermore, this dependence on two simple geometric parameters that characterize the brain also allows us to qualitatively explain how variations in these parameters lead to anatomical anomalies in such situations as polymicrogyria, pachygyria, and lissencephalia. PMID:25136099

  18. Sleep and olfactory cortical plasticity

    PubMed Central

    Barnes, Dylan C.; Wilson, Donald A.

    2014-01-01

    In many systems, sleep plays a vital role in memory consolidation and synaptic homeostasis. These processes together help store information of biological significance and reset synaptic circuits to facilitate acquisition of information in the future. In this review, we describe recent evidence of sleep-dependent changes in olfactory system structure and function which contribute to odor memory and perception. During slow-wave sleep, the piriform cortex becomes hypo-responsive to odor stimulation and instead displays sharp-wave activity similar to that observed within the hippocampal formation. Furthermore, the functional connectivity between the piriform cortex and other cortical and limbic regions is enhanced during slow-wave sleep compared to waking. This combination of conditions may allow odor memory consolidation to occur during a state of reduced external interference and facilitate association of odor memories with stored hedonic and contextual cues. Evidence consistent with sleep-dependent odor replay within olfactory cortical circuits is presented. These data suggest that both the strength and precision of odor memories is sleep-dependent. The work further emphasizes the critical role of synaptic plasticity and memory in not only odor memory but also basic odor perception. The work also suggests a possible link between sleep disturbances that are frequently co-morbid with a wide range of pathologies including Alzheimer’s disease, schizophrenia and depression and the known olfactory impairments associated with those disorders. PMID:24795585

  19. Double cortical stimulation in amyotrophic lateral sclerosis.

    PubMed Central

    Yokota, T; Yoshino, A; Inaba, A; Saito, Y

    1996-01-01

    OBJECTIVE: Transcranial double magnetic stimulation on the motor cortex was used to investigate central motor tract function in 16 patients with amyotrophic lateral sclerosis, five with spinal muscular atrophy, and 16 age matched normal controls. METHODS: Surface EMG responses were recorded from the relaxed abductor pollicis brevis (APB) muscle. RESULTS: Responses to test stimuli were markedly attenuated by a subthreshold conditioning stimulus given at a condition-test (C-T) interval of 1-4 ms in normal controls and patients with spinal muscular atrophy, but attenuation was mild in patients with amyotrophic lateral sclerosis. In the normal controls this suppression was caused by activation of the intracortical inhibitory mechanism because responses to electrical test stimuli and the H wave were not suppressed by the same magnetic subthreshold conditioning stimulus. In amyotrophic lateral sclerosis the effect of the conditioning cortical stimulus on the H wave was also in the normal range. CONCLUSION: The intracortical inhibitory mechanism may be impaired in patients with amyotrophic lateral sclerosis. PMID:8971106

  20. Spatiotemporal dynamics of early cortical gesture processing.

    PubMed

    Möhring, Nicole; Shen, Christina; Neuhaus, Andres H

    2014-10-01

    Gesture processing has been consistently shown to be associated with activation of the inferior parietal lobe (IPL); however, little is known about the integration of IPL activation into the temporal dynamics of early sensory areas. Using a temporally graded repetition suppression paradigm, we examined the activation and time course of brain areas involved in hand gesture processing. We recorded event-related potentials in response to stimulus pairs of static hand images forming gestures of the popular rock-paper-scissors game and estimated their neuronal generators. We identified two main components associated with adaptive patterns related to stimulus repetition. The N190 component elicited at temporo-parietal sites adapted to repetitions of the same gesture and was associated with right-hemispheric extrastriate body area activation. A later component at parieto-occipital sites demonstrated temporally graded adaptation effects for all gestures with a left-hemispheric dominance. Source localization revealed concurrent activations of the right extrastriate body area, fusiform gyri bilaterally, and the left IPL at about 250 ms. The adaptation pattern derived from the graded repetition suppression paradigm demonstrates the functional sensitivity of these sources to gesture processing. Given the literature on IPL contribution to imitation, action recognition, and action execution, IPL activation at about 250 ms may represent the access into specific cognitive routes for gesture processing and may thus be involved in integrating sensory information from cortical body areas into subsequent visuo-motor transformation processes. PMID:24875144

  1. Altered Cortical Communication in Amyotrophic Lateral Sclerosis

    PubMed Central

    Blain-Moraes, Stefanie; Mashour, George A.; Lee, Heonsoo; Huggins, Jane E.; Lee, UnCheol

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a disorder associated primarily with the degeneration of the motor system. More recently, functional connectivity studies have demonstrated potentially adaptive changes in ALS brain organization, but disease-related changes in cortical communication remain unknown. We recruited individuals with ALS and age-matched controls to operate a brain-computer interface while electroencephalography was recorded over three sessions. Using normalized symbolic transfer entropy, we measured directed functional connectivity from frontal to parietal (feedback connectivity) and parietal to frontal (feedforward connectivity) regions. Feedback connectivity was not significantly different between groups, but feedforward connectivity was significantly higher in individuals with ALS. This result was consistent across a broad electroencephalographic spectrum (4 – 35 Hz), and in theta, alpha and beta frequency bands. Feedback connectivity has been associated with conscious state and was found to be independent of ALS symptom severity in this study, which may have significant implications for the detection of consciousness in individuals with advanced ALS. We suggest that increases in feedforward connectivity represent a compensatory response to the ALS-related loss of input such that sensory stimuli have sufficient strength to cross the threshold necessary for conscious processing in the global neuronal workspace. PMID:23567743

  2. Cortical Synaptic Inhibition Declines during Auditory Learning

    PubMed Central

    von Trapp, Gardiner; Mowery, Todd M.; Kotak, Vibhakar C.; Sanes, Dan H.

    2015-01-01

    Auditory learning is associated with an enhanced representation of acoustic cues in primary auditory cortex, and modulation of inhibitory strength is causally involved in learning. If this inhibitory plasticity is associated with task learning and improvement, its expression should emerge and persist until task proficiency is achieved. We tested this idea by measuring changes to cortical inhibitory synaptic transmission as adult gerbils progressed through the process of associative learning and perceptual improvement. Using either of two procedures, aversive or appetitive conditioning, animals were trained to detect amplitude-modulated noise and then tested daily. Following each training session, a thalamocortical brain slice was generated, and inhibitory synaptic properties were recorded from layer 2/3 pyramidal neurons. Initial associative learning was accompanied by a profound reduction in the amplitude of spontaneous IPSCs (sIPSCs). However, sIPSC amplitude returned to control levels when animals reached asymptotic behavioral performance. In contrast, paired-pulse ratios decreased in trained animals as well as in control animals that experienced unpaired conditioned and unconditioned stimuli. This latter observation suggests that inhibitory release properties are modified during behavioral conditioning, even when an association between the sound and reinforcement cannot occur. These results suggest that associative learning is accompanied by a reduction of postsynaptic inhibitory strength that persists for several days during learning and perceptual improvement. PMID:25904785

  3. Altered cortical communication in amyotrophic lateral sclerosis.

    PubMed

    Blain-Moraes, Stefanie; Mashour, George A; Lee, Heonsoo; Huggins, Jane E; Lee, Uncheol

    2013-05-24

    Amyotrophic lateral sclerosis (ALS) is a disorder associated primarily with the degeneration of the motor system. More recently, functional connectivity studies have demonstrated potentially adaptive changes in ALS brain organization, but disease-related changes in cortical communication remain unknown. We recruited individuals with ALS and age-matched controls to operate a brain-computer interface while electroencephalography was recorded over three sessions. Using normalized symbolic transfer entropy, we measured directed functional connectivity from frontal to parietal (feedback connectivity) and parietal to frontal (feedforward connectivity) regions. Feedback connectivity was not significantly different between groups, but feedforward connectivity was significantly higher in individuals with ALS. This result was consistent across a broad electroencephalographic spectrum (4-35 Hz), and in theta, alpha and beta frequency bands. Feedback connectivity has been associated with conscious state and was found to be independent of ALS symptom severity in this study, which may have significant implications for the detection of consciousness in individuals with advanced ALS. We suggest that increases in feedforward connectivity represent a compensatory response to the ALS-related loss of input such that sensory stimuli have sufficient strength to cross the threshold necessary for conscious processing in the global neuronal workspace. PMID:23567743

  4. Interactions between thalamic and cortical rhythms during semantic memory recall in human

    NASA Astrophysics Data System (ADS)

    Slotnick, Scott D.; Moo, Lauren R.; Kraut, Michael A.; Lesser, Ronald P.; Hart, John, Jr.

    2002-04-01

    Human scalp electroencephalographic rhythms, indicative of cortical population synchrony, have long been posited to reflect cognitive processing. Although numerous studies employing simultaneous thalamic and cortical electrode recording in nonhuman animals have explored the role of the thalamus in the modulation of cortical rhythms, direct evidence for thalamocortical modulation in human has not, to our knowledge, been obtained. We simultaneously recorded from thalamic and scalp electrodes in one human during performance of a cognitive task and found a spatially widespread, phase-locked, low-frequency rhythm (7-8 Hz) power decrease at thalamus and scalp during semantic memory recall. This low-frequency rhythm power decrease was followed by a spatially specific, phase-locked, fast-rhythm (21-34 Hz) power increase at thalamus and occipital scalp. Such a pattern of thalamocortical activity reflects a plausible neural mechanism underlying semantic memory recall that may underlie other cognitive processes as well.

  5. Oscillatory Hierarchy Controlling Cortical Excitability and Stimulus Integration

    NASA Technical Reports Server (NTRS)

    Shah, A. S.; Lakatos, P.; McGinnis, T.; O'Connell, N.; Mills, A.; Knuth, K. H.; Chen, C.; Karmos, G.; Schroeder, C. E.

    2004-01-01

    Cortical gamma band oscillations have been recorded in sensory cortices of cats and monkeys, and are thought to aid in perceptual binding. Gamma activity has also been recorded in the rat hippocampus and entorhinal cortex, where it has been shown, that field gamma power is modulated at theta frequency. Since the power of gamma activity in the sensory cortices is not constant (gamma-bursts). we decided to examine the relationship between gamma power and the phase of low frequency oscillation in the auditory cortex of the awake macaque. Macaque monkeys were surgically prepared for chronic awake electrophysiological recording. During the time of the experiments. linear array multielectrodes were inserted in area AI to obtain laminar current source density (CSD) and multiunit activity profiles. Instantaneous theta and gamma power and phase was extracted by applying the Morlet wavelet transformation to the CSD. Gamma power was averaged for every 1 degree of low frequency oscillations to calculate power-phase relation. Both gamma and theta-delta power are largest in the supragranular layers. Power modulation of gamma activity is phase locked to spontaneous, as well as stimulus-related local theta and delta field oscillations. Our analysis also revealed that the power of theta oscillations is always largest at a certain phase of delta oscillation. Auditory stimuli produce evoked responses in the theta band (Le., there is pre- to post-stimulus addition of theta power), but there is also indication that stimuli may cause partial phase re-setting of spontaneous delta (and thus also theta and gamma) oscillations. We also show that spontaneous oscillations might play a role in the processing of incoming sensory signals by 'preparing' the cortex.

  6. Temporal accuracy of human cortico-cortical interactions

    PubMed Central

    Abeles, Moshe

    2016-01-01

    The precision in space and time of interactions among multiple cortical sites was evaluated by examining repeating precise spatiotemporal patterns of instances in which cortical currents showed brief amplitude undulations. The amplitudes of the cortical current dipoles were estimated by applying a variant of synthetic aperture magnetometry to magnetoencephalographic (MEG) recordings of subjects tapping to metric auditory rhythms of drum beats. Brief amplitude undulations were detected in the currents by template matching at a rate of 2–3 per second. Their timing was treated as point processes, and precise spatiotemporal patterns were searched for. By randomly teetering these point processes within a time window W, we estimated the accuracy of the timing of these brief amplitude undulations and compared the results with those obtained by applying the same analysis to traces composed of random numbers. The results demonstrated that the timing accuracy of patterns was better than 3 ms. Successful classification of two different cognitive processes based on these patterns suggests that at least some of the repeating patterns are specific to a cognitive process. PMID:26843604

  7. Modeling Higher-Order Correlations within Cortical Microcolumns

    PubMed Central

    Köster, Urs; Sohl-Dickstein, Jascha; Gray, Charles M.; Olshausen, Bruno A.

    2014-01-01

    We statistically characterize the population spiking activity obtained from simultaneous recordings of neurons across all layers of a cortical microcolumn. Three types of models are compared: an Ising model which captures pairwise correlations between units, a Restricted Boltzmann Machine (RBM) which allows for modeling of higher-order correlations, and a semi-Restricted Boltzmann Machine which is a combination of Ising and RBM models. Model parameters were estimated in a fast and efficient manner using minimum probability flow, and log likelihoods were compared using annealed importance sampling. The higher-order models reveal localized activity patterns which reflect the laminar organization of neurons within a cortical column. The higher-order models also outperformed the Ising model in log-likelihood: On populations of 20 cells, the RBM had 10% higher log-likelihood (relative to an independent model) than a pairwise model, increasing to 45% gain in a larger network with 100 spatiotemporal elements, consisting of 10 neurons over 10 time steps. We further removed the need to model stimulus-induced correlations by incorporating a peri-stimulus time histogram term, in which case the higher order models continued to perform best. These results demonstrate the importance of higher-order interactions to describe the structure of correlated activity in cortical networks. Boltzmann Machines with hidden units provide a succinct and effective way to capture these dependencies without increasing the difficulty of model estimation and evaluation. PMID:24991969

  8. Temporal accuracy of human cortico-cortical interactions.

    PubMed

    Tal, Idan; Abeles, Moshe

    2016-04-01

    The precision in space and time of interactions among multiple cortical sites was evaluated by examining repeating precise spatiotemporal patterns of instances in which cortical currents showed brief amplitude undulations. The amplitudes of the cortical current dipoles were estimated by applying a variant of synthetic aperture magnetometry to magnetoencephalographic (MEG) recordings of subjects tapping to metric auditory rhythms of drum beats. Brief amplitude undulations were detected in the currents by template matching at a rate of 2-3 per second. Their timing was treated as point processes, and precise spatiotemporal patterns were searched for. By randomly teetering these point processes within a time windowW, we estimated the accuracy of the timing of these brief amplitude undulations and compared the results with those obtained by applying the same analysis to traces composed of random numbers. The results demonstrated that the timing accuracy of patterns was better than 3 ms. Successful classification of two different cognitive processes based on these patterns suggests that at least some of the repeating patterns are specific to a cognitive process. PMID:26843604

  9. Temporomandibular disorder modifies cortical response to tactile stimulation

    PubMed Central

    Nebel, Mary Beth; Folger, Stephen; Tommerdahl, Mark; Hollins, Mark; McGlone, Francis; Essick, Gregory

    2010-01-01

    Individuals with temporomandibular disorder (TMD) suffer from persistent facial pain and exhibit abnormal sensitivity to tactile stimulation. To better understand the pathophysiological mechanisms underlying TMD, we investigated cortical correlates of this abnormal sensitivity to touch. Using functional magnetic resonance imaging (fMRI), we recorded cortical responses evoked by low frequency vibration of the index finger in subjects with TMD and in healthy controls (HC). Distinct subregions of contralateral SI, SII, and insular cortex responded maximally for each group. Although the stimulus was inaudible, primary auditory cortex was activated in TMDs. TMDs also showed greater activation bilaterally in anterior cingulate cortex and contralaterally in the amygdala. Differences between TMDs and HCs in responses evoked by innocuous vibrotactile stimulation within SI, SII, and the insula paralleled previously reported differences in responses evoked by noxious and innocuous stimulation, respectively, in healthy individuals. This unexpected result may reflect a disruption of the normal balance between central resources dedicated to processing innocuous and noxious input, manifesting itself as increased readiness of the pain matrix for activation by even innocuous input. Activation of the amygdala in our TMD group could reflect the establishment of aversive associations with tactile stimulation due to the persistence of pain. Perspective This article presents evidence that central processing of innocuous tactile stimulation is abnormal in TMD. Understanding the complexity of sensory disruption in chronic pain could lead to improved methods for assessing cerebral cortical function in these patients. PMID:20462805

  10. Anatomic variations of anterior cerebral artery cortical branches.

    PubMed

    Stefani, M A; Schneider, F L; Marrone, A C; Severino, A G; Jackowski, A P; Wallace, M C

    2000-01-01

    The anterior cerebral artery (ACA) is a major vessel responsible for the blood supply to the interhemispheric region. The ACA segment after the anterior communicating artery (AComA) origin is called the distal ACA and has central and cortical branches. The cortical branches are distributed in the different regions of the orbital and medial part of the brain. The objects of this study are the anatomical variations found in the distal ACA. In 76 hemispheres the ACA distal branches were injected with latex and dissected under microscope magnification. Vessel diameters and distances between vessel origins and anterior communicating artery were recorded and analyzed. Microsurgical dissection was carried out to demonstrate anatomic variations of these vessels. Average diameter of ACA at origin was 2.61 +/- 0.34 mm and average diameter of cortical branches diameter ranged from 0.79 +/- 0.27 mm to 1.84 +/- 0.3 mm. Distances between vessel origin and AComA ranged from 7.68 +/- 3.91 mm (orbitofrontal) to 112.6 +/- 11.63 mm (inferior internal parietal). This study found anatomical variations: a single (azygos) ACA was present in one case and three in three cases. Crossing branches of the distal ACA to the contralateral hemisphere were present in 26% of the cases. In some cases a single ACA may supply the posterior hemispheric region through crossing branches. This calls attention to potential bilateral brain infarcts due to a single unilateral ACA occlusion. PMID:10873213

  11. Global Neuromagnetic Cortical Fields Have Non-Zero Velocity.

    PubMed

    Alexander, David M; Nikolaev, Andrey R; Jurica, Peter; Zvyagintsev, Mikhail; Mathiak, Klaus; van Leeuwen, Cees

    2016-01-01

    Globally coherent patterns of phase can be obscured by analysis techniques that aggregate brain activity measures across-trials, whether prior to source localization or for estimating inter-areal coherence. We analyzed, at single-trial level, whole head MEG recorded during an observer-triggered apparent motion task. Episodes of globally coherent activity occurred in the delta, theta, alpha and beta bands of the signal in the form of large-scale waves, which propagated with a variety of velocities. Their mean speed at each frequency band was proportional to temporal frequency, giving a range of 0.06 to 4.0 m/s, from delta to beta. The wave peaks moved over the entire measurement array, during both ongoing activity and task-relevant intervals; direction of motion was more predictable during the latter. A large proportion of the cortical signal, measurable at the scalp, exists as large-scale coherent motion. We argue that the distribution of observable phase velocities in MEG is dominated by spatial filtering considerations in combination with group velocity of cortical activity. Traveling waves may index processes involved in global coordination of cortical activity. PMID:26953886

  12. Broadband cortical desynchronization underlies the human psychedelic state.

    PubMed

    Muthukumaraswamy, Suresh D; Carhart-Harris, Robin L; Moran, Rosalyn J; Brookes, Matthew J; Williams, Tim M; Errtizoe, David; Sessa, Ben; Papadopoulos, Andreas; Bolstridge, Mark; Singh, Krish D; Feilding, Amanda; Friston, Karl J; Nutt, David J

    2013-09-18

    Psychedelic drugs produce profound changes in consciousness, but the underlying neurobiological mechanisms for this remain unclear. Spontaneous and induced oscillatory activity was recorded in healthy human participants with magnetoencephalography after intravenous infusion of psilocybin--prodrug of the nonselective serotonin 2A receptor agonist and classic psychedelic psilocin. Psilocybin reduced spontaneous cortical oscillatory power from 1 to 50 Hz in posterior association cortices, and from 8 to 100 Hz in frontal association cortices. Large decreases in oscillatory power were seen in areas of the default-mode network. Independent component analysis was used to identify a number of resting-state networks, and activity in these was similarly decreased after psilocybin. Psilocybin had no effect on low-level visually induced and motor-induced gamma-band oscillations, suggesting that some basic elements of oscillatory brain activity are relatively preserved during the psychedelic experience. Dynamic causal modeling revealed that posterior cingulate cortex desynchronization can be explained by increased excitability of deep-layer pyramidal neurons, which are known to be rich in 5-HT2A receptors. These findings suggest that the subjective effects of psychedelics result from a desynchronization of ongoing oscillatory rhythms in the cortex, likely triggered by 5-HT2A receptor-mediated excitation of deep pyramidal cells. PMID:24048847

  13. Motor-Cortical Interaction in Gilles de la Tourette Syndrome

    PubMed Central

    Franzkowiak, Stephanie; Pollok, Bettina; Biermann-Ruben, Katja; Südmeyer, Martin; Paszek, Jennifer; Thomalla, Götz; Jonas, Melanie; Orth, Michael; Münchau, Alexander; Schnitzler, Alfons

    2012-01-01

    Background In Gilles de la Tourette syndrome (GTS) increased activation of the primary motor cortex (M1) before and during movement execution followed by increased inhibition after movement termination was reported. The present study aimed at investigating, whether this activation pattern is due to altered functional interaction between motor cortical areas. Methodology/Principal Findings 10 GTS-patients and 10 control subjects performed a self-paced finger movement task while neuromagnetic brain activity was recorded using Magnetoencephalography (MEG). Cerebro-cerebral coherence as a measure of functional interaction was calculated. During movement preparation and execution coherence between contralateral M1 and supplementary motor area (SMA) was significantly increased at beta-frequency in GTS-patients. After movement termination no significant differences between groups were evident. Conclusions/Significance The present data suggest that increased M1 activation in GTS-patients might be due to increased functional interaction between SMA and M1 most likely reflecting a pathophysiological marker of GTS. The data extend previous findings of motor-cortical alterations in GTS by showing that local activation changes are associated with alterations of functional networks between premotor and primary motor areas. Interestingly enough, alterations were evident during preparation and execution of voluntary movements, which implies a general theme of increased motor-cortical interaction in GTS. PMID:22238571

  14. The up and down states of cortical networks

    NASA Astrophysics Data System (ADS)

    Ghorbani, Maryam; Levine, Alex J.; Mehta, Mayank; Bruinsma, Robijn

    2011-03-01

    The cortical networks show a collective activity of alternating active and silent states known as up and down states during slow wave sleep or anesthesia. The mechanism of this spontaneous activity as well as the anesthesia or sleep are still not clear. Here, using a mean field approach, we present a simple model to study the spontaneous activity of a homogenous cortical network of excitatory and inhibitory neurons that are recurrently connected. A key new ingredient in this model is that the activity-dependant synaptic depression is considered only for the excitatory neurons. We find depending on the strength of the synaptic depression and synaptic efficacies, the phase space contains strange attractors or stable fixed points at active or quiescent regimes. At the strange attractor phase, we can have oscillations similar to up and down states with flat and noisy up states. Moreover, we show that by increasing the synaptic efficacy corresponding to the connections between the excitatory neurons, the characteristics of the up and down states change in agreement with the changes that we observe in the intracellular recordings of the membrane potential from the entorhinal cortex by varying the depth of anesthesia. Thus, we propose that by measuring the value of this synaptic efficacy, one can quantify the depth of anesthesia which is clinically very important. These findings provide a simple, analytical understanding of the spontaneous cortical dynamics.

  15. Global Neuromagnetic Cortical Fields Have Non-Zero Velocity

    PubMed Central

    Alexander, David M.; Nikolaev, Andrey R.; Jurica, Peter; Zvyagintsev, Mikhail; Mathiak, Klaus; van Leeuwen, Cees

    2016-01-01

    Globally coherent patterns of phase can be obscured by analysis techniques that aggregate brain activity measures across-trials, whether prior to source localization or for estimating inter-areal coherence. We analyzed, at single-trial level, whole head MEG recorded during an observer-triggered apparent motion task. Episodes of globally coherent activity occurred in the delta, theta, alpha and beta bands of the signal in the form of large-scale waves, which propagated with a variety of velocities. Their mean speed at each frequency band was proportional to temporal frequency, giving a range of 0.06 to 4.0 m/s, from delta to beta. The wave peaks moved over the entire measurement array, during both ongoing activity and task-relevant intervals; direction of motion was more predictable during the latter. A large proportion of the cortical signal, measurable at the scalp, exists as large-scale coherent motion. We argue that the distribution of observable phase velocities in MEG is dominated by spatial filtering considerations in combination with group velocity of cortical activity. Traveling waves may index processes involved in global coordination of cortical activity. PMID:26953886

  16. Delayed and Temporally Imprecise Neurotransmission in Reorganizing Cortical Microcircuits

    PubMed Central

    Barnes, Samuel J.; Cheetham, Claire E.; Liu, Yan; Bennett, Sophie H.; Albieri, Giorgia; Jorstad, Anne A.; Knott, Graham W.

    2015-01-01

    Synaptic neurotransmission is modified at cortical connections throughout life. Varying the amplitude of the postsynaptic response is one mechanism that generates flexible signaling in neural circuits. The timing of the synaptic response may also play a role. Here, we investigated whether weakening and loss of an entire connection between excitatory cortical neurons was foreshadowed in the timing of the postsynaptic response. We made electrophysiological recordings in rat primary somatosensory cortex that was undergoing experience-dependent loss of complete local excitatory connections. The synaptic latency of pyramid–pyramid connections, which typically comprise multiple synapses, was longer and more variable. Connection strength and latency were not correlated. Instead, prolonged latency was more closely related to progression of connection loss. The action potential waveform and axonal conduction velocity were unaffected, suggesting that the altered timing of neurotransmission was attributable to a synaptic mechanism. Modeling studies indicated that increasing the latency and jitter at a subset of synapses reduced the number of action potentials fired by a postsynaptic neuron. We propose that prolonged synaptic latency and diminished temporal precision of neurotransmission are hallmarks of impending loss of a cortical connection. PMID:26085628

  17. Visual-induced expectations modulate auditory cortical responses.

    PubMed

    van Wassenhove, Virginie; Grzeczkowski, Lukasz

    2015-01-01

    Active sensing has important consequences on multisensory processing (Schroeder et al., 2010). Here, we asked whether in the absence of saccades, the position of the eyes and the timing of transient color changes of visual stimuli could selectively affect the excitability of auditory cortex by predicting the "where" and the "when" of a sound, respectively. Human participants were recorded with magnetoencephalography (MEG) while maintaining the position of their eyes on the left, right, or center of the screen. Participants counted color changes of the fixation cross while neglecting sounds which could be presented to the left, right, or both ears. First, clear alpha power increases were observed in auditory cortices, consistent with participants' attention directed to visual inputs. Second, color changes elicited robust modulations of auditory cortex responses ("when" prediction) seen as ramping activity, early alpha phase-locked responses, and enhanced high-gamma band responses in the contralateral side of sound presentation. Third, no modulations of auditory evoked or oscillatory activity were found to be specific to eye position. Altogether, our results suggest that visual transience can automatically elicit a prediction of "when" a sound will occur by changing the excitability of auditory cortices irrespective of the attended modality, eye position or spatial congruency of auditory and visual events. To the contrary, auditory cortical responses were not significantly affected by eye position suggesting that "where" predictions may require active sensing or saccadic reset to modulate auditory cortex responses, notably in the absence of spatial orientation to sounds. PMID:25705174

  18. Modeling the effect of locus coeruleus firing on cortical state dynamics and single-trial sensory processing.

    PubMed

    Safaai, Houman; Neves, Ricardo; Eschenko, Oxana; Logothetis, Nikos K; Panzeri, Stefano

    2015-10-13

    Neuronal responses to sensory stimuli are not only driven by feedforward sensory pathways but also depend upon intrinsic factors (collectively known as the network state) that include ongoing spontaneous activity and neuromodulation. To understand how these factors together regulate cortical dynamics, we recorded simultaneously spontaneous and somatosensory-evoked multiunit activity from primary somatosensory cortex and from the locus coeruleus (LC) (the neuromodulatory nucleus releasing norepinephrine) in urethane-anesthetized rats. We found that bursts of ipsilateral-LC firing preceded by few tens of milliseconds increases of cortical excitability, and that the 1- to 10-Hz rhythmicity of LC discharge appeared to increase the power of delta-band (1-4 Hz) cortical synchronization. To investigate quantitatively how LC firing might causally influence spontaneous and stimulus-driven cortical dynamics, we then constructed and fitted to these data a model describing the dynamical interaction of stimulus drive, ongoing synchronized cortical activity, and noradrenergic neuromodulation. The model proposes a coupling between LC and cortex that can amplify delta-range cortical fluctuations, and shows how suitably timed phasic LC bursts can lead to enhanced cortical responses to weaker stimuli and increased temporal precision of cortical stimulus-evoked responses. Thus, the temporal structure of noradrenergic modulation may selectively and dynamically enhance or attenuate cortical responses to stimuli. Finally, using the model prediction of single-trial cortical stimulus-evoked responses to discount single-trial state-dependent variability increased by ∼70% the sensory information extracted from cortical responses. This suggests that downstream circuits may extract information more effectively after estimating the state of the circuit transmitting the sensory message. PMID:26417078

  19. Modeling the effect of locus coeruleus firing on cortical state dynamics and single-trial sensory processing

    PubMed Central

    Safaai, Houman; Neves, Ricardo; Eschenko, Oxana; Logothetis, Nikos K.; Panzeri, Stefano

    2015-01-01

    Neuronal responses to sensory stimuli are not only driven by feedforward sensory pathways but also depend upon intrinsic factors (collectively known as the network state) that include ongoing spontaneous activity and neuromodulation. To understand how these factors together regulate cortical dynamics, we recorded simultaneously spontaneous and somatosensory-evoked multiunit activity from primary somatosensory cortex and from the locus coeruleus (LC) (the neuromodulatory nucleus releasing norepinephrine) in urethane-anesthetized rats. We found that bursts of ipsilateral-LC firing preceded by few tens of milliseconds increases of cortical excitability, and that the 1- to 10-Hz rhythmicity of LC discharge appeared to increase the power of delta-band (1–4 Hz) cortical synchronization. To investigate quantitatively how LC firing might causally influence spontaneous and stimulus-driven cortical dynamics, we then constructed and fitted to these data a model describing the dynamical interaction of stimulus drive, ongoing synchronized cortical activity, and noradrenergic neuromodulation. The model proposes a coupling between LC and cortex that can amplify delta-range cortical fluctuations, and shows how suitably timed phasic LC bursts can lead to enhanced cortical responses to weaker stimuli and increased temporal precision of cortical stimulus-evoked responses. Thus, the temporal structure of noradrenergic modulation may selectively and dynamically enhance or attenuate cortical responses to stimuli. Finally, using the model prediction of single-trial cortical stimulus-evoked responses to discount single-trial state-dependent variability increased by ∼70% the sensory information extracted from cortical responses. This suggests that downstream circuits may extract information more effectively after estimating the state of the circuit transmitting the sensory message. PMID:26417078

  20. Chronic, multisite, multielectrode recordings in macaque monkeys

    NASA Astrophysics Data System (ADS)

    Nicolelis, Miguel A. L.; Dimitrov, Dragan; Carmena, Jose M.; Crist, Roy; Lehew, Gary; Kralik, Jerald D.; Wise, Steven P.

    2003-09-01

    A paradigm is described for recording the activity of single cortical neurons from awake, behaving macaque monkeys. Its unique features include high-density microwire arrays and multichannel instrumentation. Three adult rhesus monkeys received microwire array implants, totaling 96-704 microwires per subject, in up to five cortical areas, sometimes bilaterally. Recordings 3-4 weeks after implantation yielded 421 single neurons with a mean peak-to-peak voltage of 115 ± 3 μV and a signal-to-noise ratio of better than 5:1. As many as 247 cortical neurons were recorded in one session, and at least 58 neurons were isolated from one subject 18 months after implantation. This method should benefit neurophysiological investigation of learning, perception, and sensorimotor integration in primates and the development of neuroprosthetic devices.

  1. Cortical Activity during a Highly-Trained Resistance Exercise Movement Emphasizing Force, Power or Volume

    PubMed Central

    Flanagan, Shawn D.; Dunn-Lewis, Courtenay; Comstock, Brett A.; Maresh, Carl M.; Volek, Jeff S.; Denegar, Craig R.; Kraemer, William J.

    2012-01-01

    Cortical activity is thought to reflect the biomechanical properties of movement (e.g., force or velocity of movement), but fatigue and movement familiarity are important factors that require additional consideration in electrophysiological research. The purpose of this within-group quantitative electroencephalogram (EEG) investigation was to examine changes in cortical activity amplitude and location during four resistance exercise movement protocols emphasizing rate (PWR), magnitude (FOR), or volume (VOL) of force production, while accounting for movement familiarity and fatigue. EEG signals were recorded during each complete repetition and were then grouped by functional region, processed to eliminate artifacts, and averaged to compare overall differences in the magnitude and location of cortical activity between protocols over the course of six sets. Biomechanical, biochemical, and exertional data were collected to contextualize electrophysiological data. The most fatiguing protocols were accompanied by the greatest increases in cortical activity. Furthermore, despite non-incremental loading and lower force levels, VOL displayed the largest increases in cortical activity over time and greatest motor and sensory activity overall. Our findings suggest that cortical activity is strongly related to aspects of fatigue during a high intensity resistance exercise movement. PMID:24961265

  2. Multimodal analysis of cortical chemoarchitecture and macroscale fMRI resting-state functional connectivity.

    PubMed

    van den Heuvel, Martijn P; Scholtens, Lianne H; Turk, Elise; Mantini, Dante; Vanduffel, Wim; Feldman Barrett, Lisa

    2016-09-01

    The cerebral cortex is well known to display a large variation in excitatory and inhibitory chemoarchitecture, but the effect of this variation on global scale functional neural communication and synchronization patterns remains less well understood. Here, we provide evidence of the chemoarchitecture of cortical regions to be associated with large-scale region-to-region resting-state functional connectivity. We assessed the excitatory versus inhibitory chemoarchitecture of cortical areas as an ExIn ratio between receptor density mappings of excitatory (AMPA, M1 ) and inhibitory (GABAA , M2 ) receptors, computed on the basis of data collated from pioneering studies of autoradiography mappings as present in literature of the human (2 datasets) and macaque (1 dataset) cortex. Cortical variation in ExIn ratio significantly correlated with total level of functional connectivity as derived from resting-state functional connectivity recordings of cortical areas across all three datasets (human I: P = 0.0004; human II: P = 0.0008; macaque: P = 0.0007), suggesting cortical areas with an overall more excitatory character to show higher levels of intrinsic functional connectivity during resting-state. Our findings are indicative of the microscale chemoarchitecture of cortical regions to be related to resting-state fMRI connectivity patterns at the global system's level of connectome organization. Hum Brain Mapp 37:3103-3113, 2016. © 2016 Wiley Periodicals, Inc. PMID:27207489

  3. Early unilateral cochlear implantation promotes mature cortical asymmetries in adolescents who are deaf.

    PubMed

    Jiwani, Salima; Papsin, Blake C; Gordon, Karen A

    2016-01-01

    Unilateral cochlear implant (CI) stimulation establishes hearing to children who are deaf but compromises bilateral auditory development if a second implant is not provided within ∼ 1.5 years. In this study we asked: 1) What are the cortical consequences of missing this early sensitive period once children reach adolescence? 2) What are the effects of unilateral deprivation on the pathways from the opposite ear? Cortical responses were recorded from 64-cephalic electrodes within the first week of bilateral CI activation in 34 adolescents who had over 10 years of unilateral right CI experience and in 16 normal hearing peers. Cortical activation underlying the evoked peaks was localized to areas of the brain using beamformer imaging. The first CI evoked activity which was more strongly lateralized to the contralateral left hemisphere than normal, with abnormal recruitment of the left prefrontal cortex (involved in cognition/attention), left temporo-parietal-occipital junction (multi-modal integration), and right precuneus (visual processing) region. CI stimulation in the opposite deprived ear evoked atypical cortical responses with abnormally large and widespread dipole activity across the cortex. Thus, using a unilateral CI to hear beyond the period of cortical maturation causes lasting asymmetries in the auditory system, requires recruitment of additional cortical areas to support hearing, and does little to protect the unstimulated pathways from effects of auditory deprivation. The persistence of this reorganization into maturity could signal a closing of a sensitive period for promoting auditory development on the deprived side. PMID:26456629

  4. Multilevel Cortical Processing of Somatosensory Novelty: A Magnetoencephalography Study

    PubMed Central

    Naeije, Gilles; Vaulet, Thibaut; Wens, Vincent; Marty, Brice; Goldman, Serge; De Tiège, Xavier

    2016-01-01

    Using magnetoencephalography (MEG), this study investigates the spatio-temporal dynamics of the multilevel cortical processing of somatosensory change detection. Neuromagnetic signals of 16 healthy adult subjects (7 females and 9 males, mean age 29 ± 3 years) were recorded using whole-scalp-covering MEG while they underwent an oddball paradigm based on simple standard (right index fingertip tactile stimulation) and deviant (simultaneous right index fingertip and middle phalanx tactile stimulation) stimuli gathered into sequences to create and then deviate from stimulus patterns at multiple (local vs. global) levels of complexity. Five healthy adult subjects (3 females and 2 males, mean age 31, 6 ± 2 years) also underwent a similar oddball paradigm in which standard and deviant stimuli were flipped. Local deviations led to a somatosensory mismatch response peaking at 55–130 ms post-stimulus onset with a cortical generator located at the contralateral secondary somatosensory (cSII) cortex. The mismatch response was independent of the deviant stimuli physical characteristics. Global deviants led to a P300 response with cortical sources located bilaterally at temporo-parietal junction (TPJ) and supplementary motor area (SMA). The posterior parietal cortex (PPC) and the SMA were found to generate a contingent magnetic variation (CMV) attributed to top-down expectations. Amplitude of mismatch responses were modulated by top-down expectations and correlated with both the magnitude of the CMV and the P300 amplitude at the right TPJ. These results provide novel empirical evidence for a unified sensory novelty detection system in the human brain by linking detection of salient sensory stimuli in personal and extra-personal spaces to a common framework of multilevel cortical processing. PMID:27313523

  5. Multilevel Cortical Processing of Somatosensory Novelty: A Magnetoencephalography Study.

    PubMed

    Naeije, Gilles; Vaulet, Thibaut; Wens, Vincent; Marty, Brice; Goldman, Serge; De Tiège, Xavier

    2016-01-01

    Using magnetoencephalography (MEG), this study investigates the spatio-temporal dynamics of the multilevel cortical processing of somatosensory change detection. Neuromagnetic signals of 16 healthy adult subjects (7 females and 9 males, mean age 29 ± 3 years) were recorded using whole-scalp-covering MEG while they underwent an oddball paradigm based on simple standard (right index fingertip tactile stimulation) and deviant (simultaneous right index fingertip and middle phalanx tactile stimulation) stimuli gathered into sequences to create and then deviate from stimulus patterns at multiple (local vs. global) levels of complexity. Five healthy adult subjects (3 females and 2 males, mean age 31, 6 ± 2 years) also underwent a similar oddball paradigm in which standard and deviant stimuli were flipped. Local deviations led to a somatosensory mismatch response peaking at 55-130 ms post-stimulus onset with a cortical generator located at the contralateral secondary somatosensory (cSII) cortex. The mismatch response was independent of the deviant stimuli physical characteristics. Global deviants led to a P300 response with cortical sources located bilaterally at temporo-parietal junction (TPJ) and supplementary motor area (SMA). The posterior parietal cortex (PPC) and the SMA were found to generate a contingent magnetic variation (CMV) attributed to top-down expectations. Amplitude of mismatch responses were modulated by top-down expectations and correlated with both the magnitude of the CMV and the P300 amplitude at the right TPJ. These results provide novel empirical evidence for a unified sensory novelty detection system in the human brain by linking detection of salient sensory stimuli in personal and extra-personal spaces to a common framework of multilevel cortical processing. PMID:27313523

  6. Cortical cartography and Caret software.

    PubMed

    Van Essen, David C

    2012-08-15

    Caret software is widely used for analyzing and visualizing many types of fMRI data, often in conjunction with experimental data from other modalities. This article places Caret's development in a historical context that spans three decades of brain mapping--from the early days of manually generated flat maps to the nascent field of human connectomics. It also highlights some of Caret's distinctive capabilities. This includes the ease of visualizing data on surfaces and/or volumes and on atlases as well as individual subjects. Caret can display many types of experimental data using various combinations of overlays (e.g., fMRI activation maps, cortical parcellations, areal boundaries), and it has other features that facilitate the analysis and visualization of complex neuroimaging datasets. PMID:22062192

  7. Gyrification from constrained cortical expansion

    NASA Astrophysics Data System (ADS)

    Tallinen, Tuomas

    The convolutions of the human brain are a symbol of its functional complexity. But how does the outer surface of the brain, the layered cortex of neuronal gray matter get its folds? In this talk, we ask to which extent folding of the brain can be explained as a purely mechanical consequence of unpatterned growth of the cortical layer relative to the sublayers. Modeling the growing brain as a soft layered solid leads to elastic instabilities and the formation of cusped sulci and smooth gyri consistent with observations across species in both normal and pathological situations. Furthermore, we apply initial geometries obtained from fetal brain MRI to address the question of how the brain geometry and folding patterns may be coupled via mechanics.

  8. Cortical Cartography and Caret Software

    PubMed Central

    Van Essen, David C.

    2011-01-01

    Caret software is widely used for analyzing and visualizing many types of fMRI data, often in conjunction with experimental data from other modalities. This article places Caret’s development in a historical context that spans three decades of brain mapping – from the early days of manually generated flat maps to the nascent field of human connectomics. It also highlights some of Caret’s distinctive capabilities. This includes the ease of visualizing data on surfaces and/or volumes and on atlases as well as individual subjects. Caret can display many types of experimental data using various combinations of overlays (e.g., fMRI activation maps, cortical parcellations, areal boundaries), and it has other features that facilitate the analysis and visualization of complex neuroimaging datasets. PMID:22062192

  9. Cortical Response Variability as a Developmental Index of Selective Auditory Attention

    ERIC Educational Resources Information Center

    Strait, Dana L.; Slater, Jessica; Abecassis, Victor; Kraus, Nina

    2014-01-01

    Attention induces synchronicity in neuronal firing for the encoding of a given stimulus at the exclusion of others. Recently, we reported decreased variability in scalp-recorded cortical evoked potentials to attended compared with ignored speech in adults. Here we aimed to determine the developmental time course for this neural index of auditory…

  10. Cortical spreading depression: An enigma

    NASA Astrophysics Data System (ADS)

    Miura, R. M.; Huang, H.; Wylie, J. J.

    2007-08-01

    The brain is a complex organ with active components composed largely of neurons, glial cells, and blood vessels. There exists an enormous experimental and theoretical literature on the mechanisms involved in the functioning of the brain, but we still do not have a good understanding of how it works on a gross mechanistic level. In general, the brain maintains a homeostatic state with relatively small ion concentration changes, the major ions being sodium, potassium, and chloride. Calcium ions are present in smaller quantities but still play an important role in many phenomena. Cortical spreading depression (CSD for short) was discovered over 60 years ago by A.A.P. Leão, a Brazilian physiologist doing his doctoral research on epilepsy at Harvard University, “Spreading depression of activity in the cerebral cortex," J. Neurophysiol., 7 (1944), pp. 359-390. Cortical spreading depression is characterized by massive changes in ionic concentrations and slow nonlinear chemical waves, with speeds on the order of mm/min, in the cortex of different brain structures in various experimental animals. In humans, CSD is associated with migraine with aura, where a light scintillation in the visual field propagates, then disappears, and is followed by a sustained headache. To date, CSD remains an enigma, and further detailed experimental and theoretical investigations are needed to develop a comprehensive picture of the diverse mechanisms involved in producing CSD. A number of mechanisms have been hypothesized to be important for CSD wave propagation. In this paper, we briefly describe several characteristics of CSD wave propagation, and examine some of the mechanisms that are believed to be important, including ion diffusion, membrane ionic currents, osmotic effects, spatial buffering, neurotransmitter substances, gap junctions, metabolic pumps, and synaptic connections. Continuum models of CSD, consisting of coupled nonlinear diffusion equations for the ion concentrations, and

  11. Unsupervised fetal cortical surface parcellation

    NASA Astrophysics Data System (ADS)

    Dahdouh, Sonia; Limperopoulos, Catherine

    2016-03-01

    At the core of many neuro-imaging studies, atlas-based brain parcellations are used for example to study normal brain evolution across the lifespan. These atlases rely on the assumption that the same anatomical features are present on all subjects to be studied and that these features are stable enough to allow meaningful comparisons between different brain surfaces and structures These methods, however, often fail when applied to fetal MRI data, due to the lack of consistent anatomical features present across gestation. This paper presents a novel surface-based fetal cortical parcellation framework which attempts to circumvent the lack of consistent anatomical features by proposing a brain parcellation scheme that is based solely on learned geometrical features. A mesh signature incorporating both extrinsic and intrinsic geometrical features is proposed and used in a clustering scheme to define a parcellation of the fetal brain. This parcellation is then learned using a Random Forest (RF) based learning approach and then further refined in an alpha-expansion graph-cut scheme. Based on the votes obtained by the RF inference procedure, a probability map is computed and used as a data term in the graph-cut procedure. The smoothness term is defined by learning a transition matrix based on the dihedral angles of the faces. Qualitative and quantitative results on a cohort of both healthy and high-risk fetuses are presented. Both visual and quantitative assessments show good results demonstrating a reliable method for fetal brain data and the possibility of obtaining a parcellation of the fetal cortical surfaces using only geometrical features.

  12. Cortical dysfunction underlies the development of the split-hand in amyotrophic lateral sclerosis.

    PubMed

    Menon, Parvathi; Kiernan, Matthew C; Vucic, Steve

    2014-01-01

    The split-hand phenomenon, a specific feature of amyotrophic lateral sclerosis (ALS), refers to preferential wasting of abductor pollicis brevis (APB) and first dorsal interosseous (FDI) with relative preservation of abductor digiti minimi (ADM). The pathophysiological mechanisms underlying the split-hand phenomenon remain elusive and resolution of this issue would provide unique insights into ALS pathophysiology. Consequently, the present study dissected out the relative contribution of cortical and peripheral processes in development of the split-hand phenomenon in ALS. Cortical and axonal excitability studies were undertaken on 26 ALS patients, with motor responses recorded over the APB, FDI and ADM muscles. Results were compared to 21 controls. Short interval intracortical inhibition (SICI), a biomarker of cortical excitability, was significantly reduced across the range of intrinsic hand muscles (APB(SICI ALS) 0.3±2.0%, APB(SICI controls) 16.0±1.9%, P<0.0001; FDI(SICI ALS) 2.7±1.7%, FDI(SICI controls) 14.8±1.9%, P<0.0001; ADM(SICI ALS) 2.6±1.5%, ADM(SICI controls) 9.7±2.2%, P<0.001), although the reduction was most prominent when recorded over APB/FDI. Changes in SICI were accompanied by a significant increase in motor evoked potential amplitude and reduction of cortical silent period duration, all indicative of cortical hyperexcitability, and these were most prominent from the APB/FDI. At a peripheral level, a significant increase in strength-duration time constant and reduction in depolarising threshold electrotonus were evident in ALS, although these changes did not follow a split-hand distribution. Cortical dysfunction contributed to development of the split-hand in ALS, thereby implying an importance of cortical hyperexcitability in ALS pathogenesis. PMID:24475241

  13. Correlation between Cortical State and Locus Coeruleus Activity: Implications for Sensory Coding in Rat Barrel Cortex

    PubMed Central

    Fazlali, Zeinab; Ranjbar-Slamloo, Yadollah; Adibi, Mehdi; Arabzadeh, Ehsan

    2016-01-01

    Cortical state modulates the background activity of cortical neurons, and their evoked response to sensory stimulation. Multiple mechanisms are involved in switching between cortical states including various neuromodulatory systems. Locus Coeruleus (LC) is one of the major neuromodulatory nuclei in the brainstem with widespread projections throughout the brain and modulates the activity of cells and networks. Here, we quantified the link between the LC spontaneous activity, cortical state and sensory processing in the rat vibrissal somatosensory “barrel” cortex (BC). We simultaneously recorded unit activity from LC and BC along with prefrontal electroencephalogram (EEG) while presenting brief whisker deflections under urethane anesthesia. The ratio of low to high frequency components of EEG (referred to as the L/H ratio) was employed to identify cortical state. We found that the spontaneous activity of LC units exhibited a negative correlation with the L/H ratio. Cross-correlation analysis revealed that changes in LC firing preceded changes in the cortical state: the correlation of the LC firing profile with the L/H ratio was maximal at an average lag of −1.2 s. We further quantified BC neuronal responses to whisker stimulation during the synchronized and desynchronized states. In the desynchronized state, BC neurons showed lower stimulus detection threshold, higher response fidelity, and shorter response latency. The most prominent change was observed in the late phase of BC evoked activity (100–400 ms post stimulus onset): almost every BC unit exhibited a greater late response during the desynchronized state. Categorization of the BC evoked responses based on LC activity (into high and low LC discharge rates) resulted in highly similar response profiles compared to categorization based on the cortical state (low and high L/H ratios). These findings provide evidence for the involvement of the LC neuromodulatory system in desynchronization of cortical state

  14. Cortical brain states and corticospinal synchronization influence TMS-evoked motor potentials.

    PubMed

    Keil, Julian; Timm, Jana; Sanmiguel, Iria; Schulz, Hannah; Obleser, Jonas; Schönwiesner, Marc

    2014-02-01

    Transcranial magnetic stimulation (TMS) influences cortical processes. Recent findings indicate, however, that, in turn, the efficacy of TMS depends on the state of ongoing cortical oscillations. Whereas power and phase of electromyographic (EMG) activity recorded from the hand muscles as well as neural synchrony between cortex and hand muscles are known to influence the effect of TMS, to date, no study has shown an influence of the phase of cortical oscillations during wakefulness. We applied single-pulse TMS over the motor cortex and recorded motor-evoked potentials along with the electroencephalogram (EEG) and EMG. We correlated phase and power of ongoing EEG and EMG signals with the motor-evoked potential (MEP) amplitude. We also investigated the functional connectivity between cortical and hand muscle activity (corticomuscular coherence) with the MEP amplitude. EEG and EMG power and phase in a frequency band around 18 Hz correlated with the MEP amplitude. High beta-band (∼34 Hz) corticomuscular coherence exhibited a positive linear relationship with the MEP amplitude, indicating that strong synchrony between cortex and hand muscles at the moment when TMS is applied entails large MEPs. Improving upon previous studies, we demonstrate a clear dependence of TMS-induced motor effects on the state of ongoing EEG phase and power fluctuations. We conclude that not only the sampling of incoming information but also the susceptibility of cortical communication flow depends cyclically on neural phase. PMID:24198325

  15. Spatiotemporal SERT expression in cortical map development.

    PubMed

    Chen, Xiaoning; Petit, Emilie I; Dobrenis, Kostantin; Sze, Ji Ying

    2016-09-01

    The cerebral cortex is organized into morphologically distinct areas that provide biological frameworks underlying perception, cognition, and behavior. Profiling mouse and human cortical transcriptomes have revealed temporal-specific differential gene expression modules in distinct neocortical areas during cortical map establishment. However, the biological roles of spatiotemporal gene expression in cortical patterning and how cortical topographic gene expression is regulated are largely unknown. Here, we characterize temporal- and spatial-defined expression of serotonin (5-HT) transporter (SERT) in glutamatergic neurons during sensory map development in mice. SERT is transiently expressed in glutamatergic thalamic neurons projecting to sensory cortices and in pyramidal neurons in the prefrontal cortex (PFC) and hippocampus (HPC) during the period that lays down the basic functional neural circuits. We previously identified that knockout of SERT in the thalamic neurons blocks 5-HT uptake by their thalamocortical axons, resulting in excessive 5-HT signaling that impairs sensory map architecture. In contrast, here we show that selective SERT knockout in the PFC and HPC neurons does not perturb sensory map patterning. These data suggest that transient SERT expression in specific glutamatergic neurons provides area-specific instructions for cortical map patterning. Hence, genetic and pharmacological manipulations of this SERT function could illuminate the fundamental genetic programming of cortex-specific maps and biological roles of temporal-specific cortical topographic gene expression in normal development and mental disorders. PMID:27282696

  16. Cortical feedback control of olfactory bulb circuits.

    PubMed

    Boyd, Alison M; Sturgill, James F; Poo, Cindy; Isaacson, Jeffry S

    2012-12-20

    Olfactory cortex pyramidal cells integrate sensory input from olfactory bulb mitral and tufted (M/T) cells and project axons back to the bulb. However, the impact of cortical feedback projections on olfactory bulb circuits is unclear. Here, we selectively express channelrhodopsin-2 in olfactory cortex pyramidal cells and show that cortical feedback projections excite diverse populations of bulb interneurons. Activation of cortical fibers directly excites GABAergic granule cells, which in turn inhibit M/T cells. However, we show that cortical inputs preferentially target short axon cells that drive feedforward inhibition of granule cells. In vivo, activation of olfactory cortex that only weakly affects spontaneous M/T cell firing strongly gates odor-evoked M/T cell responses: cortical activity suppresses odor-evoked excitation and enhances odor-evoked inhibition. Together, these results indicate that although cortical projections have diverse actions on olfactory bulb microcircuits, the net effect of cortical feedback on M/T cells is an amplification of odor-evoked inhibition. PMID:23259951

  17. Influence of contralateral homologous cortices on motor cortical reorganization after brachial plexus injuries in rats.

    PubMed

    Zhang, Jie; Chen, Liang; Gu, Yu-dong

    2015-10-01

    Brachial plexus injuries induce corresponding cortical representations to be occupied by adjacent cortices. The purpose of this study was to clarify if contralateral homologous motor regions of adjacent cortices influence occupation of deafferented motor cortex. 36 rats were divided into 3 groups of 12 each. In group 1, total brachial plexus root avulsion (tBPRA) was made on the left side. In group 2, rats underwent left tBPRA combined with corpus callosum transection (CCX). In group 3, only CCX was performed. 6 rats in each group were used for intracortical microstimulation (ICMS) to map representations of motor cortex in the right hemisphere at 7 days and the other 6 rats, at 3 months. 18 more rats without any operation underwent ICMS, with 6 each taken to serve as normal control for motor cortical representations' changes caused by different surgery. Results showed that in groups 1 and 2, sites for motor cortical representations of vibrissae, of neck and of the hindlimb was statistically more than that of control, respectively, and statistically more sites were found at 3 months than at 7 days, respectively. At the two time points, sites for vibrissa cortices and that for the hindlimb were statistically more in group 2 than in group 1, respectively. CCX alone did not induce change of site number for motor cortical representations. We conclude that after tBPRA, contralateral homologous motor cortices may, to some extent, prevent neighboring cortices from encroachment on motor cortical representations of the brachial plexus. PMID:26314511

  18. Cerebral perfusion and cortical thickness indicate cortical involvement in mild Parkinson's disease.

    PubMed

    Madhyastha, Tara M; Askren, Mary K; Boord, Peter; Zhang, Jing; Leverenz, James B; Grabowski, Thomas J

    2015-12-01

    Cortical dysfunction in Parkinson's disease (PD) may be caused by disruption to ascending systems or by intrinsic cortical neuropathology. We introduce and conduct a joint analysis of metabolism and atrophy capable of identifying whether metabolic disruption occurs in mild PD without cortical atrophy, to determine the extent and spatial pattern of cortical involvement in mild PD. The design was observational, studying 23 cognitively normal participants with mild PD (mean Hoehn & Yahr stage 2) and 21 healthy controls. Cortical thickness (obtained from analysis of structural magnetic resonance imaging [MRI] with FreeSurfer) and cerebral perfusion measures (obtained from arterial spin labeling [ASL]) analyzed independently and then together in a joint multiple factorial analysis to identify spatial patterns of perfusion and cortical thickness. We identify a pattern of changes in perfusion and cortical thickness characterized by symmetric parietal cortical thinning and reduced precuneus perfusion, with relative preservation of thickness and perfusion in the anterior cingulate cortex (ACC), right prefrontal gyrus, and medial frontal gyrus. The expression of this pattern is correlated with motor system symptoms and speed of processing. A spatial pattern of joint parietal cortical thinning and disproportionate reduction in perfusion occurs in our nondemented PD sample. We found no PD-related components of reduced perfusion without cortical thinning. This suggests that PD affects the cortex itself, even when symptoms are relatively mild. PMID:25759166

  19. A Turing Reaction-Diffusion Model for Human Cortical Folding Patterns and Cortical Pattern Malformations

    NASA Astrophysics Data System (ADS)

    Hurdal, Monica K.; Striegel, Deborah A.

    2011-11-01

    Modeling and understanding cortical folding pattern formation is important for quantifying cortical development. We present a biomathematical model for cortical folding pattern formation in the human brain and apply this model to study diseases involving cortical pattern malformations associated with neural migration disorders. Polymicrogyria is a cortical malformation disease resulting in an excessive number of small gyri. Our mathematical model uses a Turing reaction-diffusion system to model cortical folding. The lateral ventricle (LV) and ventricular zone (VZ) of the brain are critical components in the formation of cortical patterning. In early cortical development the shape of the LV can be modeled with a prolate spheroid and the VZ with a prolate spheroid surface. We use our model to study how global cortex characteristics, such as size and shape of the LV, affect cortical pattern formation. We demonstrate increasing domain scale can increase the number of gyri and sulci formed. Changes in LV shape can account for sulcus directionality. By incorporating LV size and shape, our model is able to elucidate which parameters can lead to excessive cortical folding.

  20. Subthalamic stimulation modulates cortical motor network activity and synchronization in Parkinson's disease.

    PubMed

    Weiss, Daniel; Klotz, Rosa; Govindan, Rathinaswamy B; Scholten, Marlieke; Naros, Georgios; Ramos-Murguialday, Ander; Bunjes, Friedemann; Meisner, Christoph; Plewnia, Christian; Krüger, Rejko; Gharabaghi, Alireza

    2015-03-01

    Dynamic modulations of large-scale network activity and synchronization are inherent to a broad spectrum of cognitive processes and are disturbed in neuropsychiatric conditions including Parkinson's disease. Here, we set out to address the motor network activity and synchronization in Parkinson's disease and its modulation with subthalamic stimulation. To this end, 20 patients with idiopathic Parkinson's disease with subthalamic nucleus stimulation were analysed on externally cued right hand finger movements with 1.5-s interstimulus interval. Simultaneous recordings were obtained from electromyography on antagonistic muscles (right flexor digitorum and extensor digitorum) together with 64-channel electroencephalography. Time-frequency event-related spectral perturbations were assessed to determine cortical and muscular activity. Next, cross-spectra in the time-frequency domain were analysed to explore the cortico-cortical synchronization. The time-frequency modulations enabled us to select a time-frequency range relevant for motor processing. On these time-frequency windows, we developed an extension of the phase synchronization index to quantify the global cortico-cortical synchronization and to obtain topographic differentiations of distinct electrode sites with respect to their contributions to the global phase synchronization index. The spectral measures were used to predict clinical and reaction time outcome using regression analysis. We found that movement-related desynchronization of cortical activity in the upper alpha and beta range was significantly facilitated with 'stimulation on' compared to 'stimulation off' on electrodes over the bilateral parietal, sensorimotor, premotor, supplementary-motor, and prefrontal areas, including the bilateral inferior prefrontal areas. These spectral modulations enabled us to predict both clinical and reaction time improvement from subthalamic stimulation. With 'stimulation on', interhemispheric cortico-cortical

  1. Phase reversal technique decreases cortical stimulation time during motor mapping.

    PubMed

    Simon, Mirela V; Sheth, Sameer A; Eckhardt, Christine A; Kilbride, Ronan D; Braver, Diana; Williams, Ziv; Curry, William; Cahill, Dan; Eskandar, Emad N

    2014-06-01

    Neurophysiologic mapping of the primary motor cortex (PMC) is commonly used in supratentorial surgery. Electrical cortical stimulation is guided by anatomic landmarks towards the precentral gyrus, with recording of the triggered primary motor responses (TPMR) in the contralateral hemibody. Thus, factors such as distortion of the pericentral anatomy, small surgical fields, brain shifts and miscalibrated neuronavigational systems may lengthen the process and result in unnecessary stimulations, increasing the probability of triggering seizures. We hypothesized that central sulcus localization via the median somatosensory evoked potentials phase reversal technique (MSSEP PRT) accurately guides the surgeon, resulting in prompt identification of the PMC with minimal electrical stimulation. Multivariate Cox regression was used to study the impact of MSSEP PRT on time spent performing electrical cortical stimulation to TPMR. The analysis was adjusted for presence of increased cortical excitability, high motor thresholds, lesions close to PMC and fMRI data, in 100 consecutive standardized motor mapping procedures for brain tumor resection and epilepsy surgery. Phase reversal and change morphology of the recorded somatosensory evoked potentials quadrupled (hazard ratio [HR] 4.13, p<0.0001) and doubled (HR 2.14, p=0.02) the rate of obtaining TPMR, respectively. A 1mA increase in motor threshold decreased the rate by 9% (HR 0.91, p=0.0002). Afterdischarges triggered before TPMR and lesions in close proximity to PMC decreased the rate of TPMR by 76% (HR 0.23, p<0.0001) and 48% (HR 0.52, p=0.04), respectively. Informative PRT decreases stimulation time. Afterdischarges triggered before TPMR, high motor thresholds and lesions close to the PMC increase it. PMID:24679940

  2. Cortical astrocytes rewire somatosensory cortical circuits for peripheral neuropathic pain

    PubMed Central

    Hayashi, Hideaki; Ishikawa, Tatsuya; Shibata, Keisuke; Inada, Hiroyuki; Roh, Seung Eon; Kim, Sang Jeong; Moorhouse, Andrew J.

    2016-01-01

    Long-term treatments to ameliorate peripheral neuropathic pain that includes mechanical allodynia are limited. While glial activation and altered nociceptive transmission within the spinal cord are associated with the pathogenesis of mechanical allodynia, changes in cortical circuits also accompany peripheral nerve injury and may represent additional therapeutic targets. Dendritic spine plasticity in the S1 cortex appears within days following nerve injury; however, the underlying cellular mechanisms of this plasticity and whether it has a causal relationship to allodynia remain unsolved. Furthermore, it is not known whether glial activation occurs within the S1 cortex following injury or whether it contributes to this S1 synaptic plasticity. Using in vivo 2-photon imaging with genetic and pharmacological manipulations of murine models, we have shown that sciatic nerve ligation induces a re-emergence of immature metabotropic glutamate receptor 5 (mGluR5) signaling in S1 astroglia, which elicits spontaneous somatic Ca2+ transients, synaptogenic thrombospondin 1 (TSP-1) release, and synapse formation. This S1 astrocyte reactivation was evident only during the first week after injury and correlated with the temporal changes in S1 extracellular glutamate levels and dendritic spine turnover. Blocking the astrocytic mGluR5-signaling pathway suppressed mechanical allodynia, while activating this pathway in the absence of any peripheral injury induced long-lasting (>1 month) allodynia. We conclude that reawakened astrocytes are a key trigger for S1 circuit rewiring and that this contributes to neuropathic mechanical allodynia. PMID:27064281

  3. Cortical astrocytes rewire somatosensory cortical circuits for peripheral neuropathic pain.

    PubMed

    Kim, Sun Kwang; Hayashi, Hideaki; Ishikawa, Tatsuya; Shibata, Keisuke; Shigetomi, Eiji; Shinozaki, Youichi; Inada, Hiroyuki; Roh, Seung Eon; Kim, Sang Jeong; Lee, Gihyun; Bae, Hyunsu; Moorhouse, Andrew J; Mikoshiba, Katsuhiko; Fukazawa, Yugo; Koizumi, Schuichi; Nabekura, Junichi

    2016-05-01

    Long-term treatments to ameliorate peripheral neuropathic pain that includes mechanical allodynia are limited. While glial activation and altered nociceptive transmission within the spinal cord are associated with the pathogenesis of mechanical allodynia, changes in cortical circuits also accompany peripheral nerve injury and may represent additional therapeutic targets. Dendritic spine plasticity in the S1 cortex appears within days following nerve injury; however, the underlying cellular mechanisms of this plasticity and whether it has a causal relationship to allodynia remain unsolved. Furthermore, it is not known whether glial activation occurs within the S1 cortex following injury or whether it contributes to this S1 synaptic plasticity. Using in vivo 2-photon imaging with genetic and pharmacological manipulations of murine models, we have shown that sciatic nerve ligation induces a re-emergence of immature metabotropic glutamate receptor 5 (mGluR5) signaling in S1 astroglia, which elicits spontaneous somatic Ca2+ transients, synaptogenic thrombospondin 1 (TSP-1) release, and synapse formation. This S1 astrocyte reactivation was evident only during the first week after injury and correlated with the temporal changes in S1 extracellular glutamate levels and dendritic spine turnover. Blocking the astrocytic mGluR5-signaling pathway suppressed mechanical allodynia, while activating this pathway in the absence of any peripheral injury induced long-lasting (>1 month) allodynia. We conclude that reawakened astrocytes are a key trigger for S1 circuit rewiring and that this contributes to neuropathic mechanical allodynia. PMID:27064281

  4. Linking cortical network synchrony and excitability

    PubMed Central

    Meisel, Christian

    2016-01-01

    ABSTRACT Theoretical approaches based on dynamical systems theory can provide useful frameworks to guide experiments and analysis techniques when investigating cortical network activity. The notion of phase transitions between qualitatively different kinds of network dynamics has been such a framework inspiring novel approaches to neurophysiological data analysis over the recent years. One particular intriguing hypothesis has been that cortical networks reside in the vicinity of a phase transition. Although the final verdict on this hypothesis is still out, trying to understand cortex dynamics from this viewpoint has recently led to interesting insights on cortical network function with relevance for clinical practice. PMID:27065159

  5. Early visual cortical responses produced by checkerboard pattern stimulation.

    PubMed

    Shigihara, Yoshihito; Hoshi, Hideyuki; Zeki, Semir

    2016-07-01

    Visual evoked potentials have been traditionally triggered with flash or reversing checkerboard stimuli and recorded with electroencephalographic techniques, largely but not exclusively in clinical or clinically related settings. They have been crucial in determining the healthy functioning or otherwise of the visual pathways up to and including the cerebral cortex. They have typically given early response latencies of 100ms, the source of which has been attributed to V1, with the prestriate cortex being secondarily activated somewhat later. On the other hand, magnetoencephalographic studies using stimuli better tailored to the physiology of individual, specialized, visual areas have given early latencies of <50ms with the sources localized in both striate (V1) and prestriate cortex. In this study, we used the reversing checkerboard pattern as a stimulus and recorded cortical visual evoked magnetic fields with magnetoencephalography, to establish whether very early responses can be traced to (estimated) in both striate and prestriate cortex, since such a demonstration would enhance considerably the power of this classical approach in clinical investigations. Our results show that cortical responses evoked by checkerboard patterns can be detected before 50ms post-stimulus onset and that their sources can be estimated in both striate and prestriate cortex, suggesting a strong parallel input from the sub-cortex to both striate and prestriate divisions of the visual cortex. PMID:27083528

  6. Rich club neurons dominate Information Transfer in local cortical networks

    NASA Astrophysics Data System (ADS)

    Nigam, Sunny; Shimono, Masanori; Sporns, Olaf; Beggs, John

    2015-03-01

    The performance of complex networks depends on how they route their traffic. It is unknown how information is transferred in local cortical networks of hundreds of closely-spaced neurons. To address this, it is necessary to record simultaneously from hundreds of neurons at a spacing that matches typical axonal connection distances, and at a temporal resolution that matches synaptic delays. We used a 512 electrode array (60 μm spacing) to record spontaneous activity at 20 kHz, simultaneously from up to 700 neurons in slice cultures of mouse somatosensory cortex for 1 hr at a time. We used transfer entropy to quantify directed information transfer (IT) between pairs of neurons. We found an approximately lognormal distribution of firing rates as reported in in-vivo. Pairwise information transfer strengths also were nearly lognormally distributed, similar to synaptic strengths. 20% of the neurons accounted for 70% of the total IT coming into, and going out of the network and were defined as rich nodes. These rich nodes were more densely and strongly connected to each other expected by chance, forming a rich club. This highly uneven distribution of IT has implications for the efficiency and robustness of local cortical networks, and gives clues to the plastic processes that shape them. JSPS.

  7. Effects of intrathecal baclofen on lumbosacral and cortical somatosensory evoked potentials.

    PubMed

    Kofler, M; Donovan, W H; Loubser, P G; Berić, A

    1992-04-01

    We analyzed lumbosacral and cortical somatosensory evoked potentials in three spinal cord injury patients undergoing evaluation of intrathecal baclofen infusion for management of spasticity. The cauda equina propagating root wave (R wave) and conus medullaris postsynaptic responses (S and P waves) were analyzed before and during baclofen infusion. Baclofen abolished the concomitantly recorded H-reflex and markedly suppressed the P wave amplitude and area. The S wave amplitude and area were suppressed to a lesser degree. In contrast, there were no significant changes in cortical somatosensory evoked potentials. PMID:1565243

  8. Robustness of cortical topography across fields, laminae, anesthetic states, and neurophysiological signal types.

    PubMed

    Guo, Wei; Chambers, Anna R; Darrow, Keith N; Hancock, Kenneth E; Shinn-Cunningham, Barbara G; Polley, Daniel B

    2012-07-01

    Topographically organized maps of the sensory receptor epithelia are regarded as cornerstones of cortical organization as well as valuable readouts of diverse biological processes ranging from evolution to neural plasticity. However, maps are most often derived from multiunit activity recorded in the thalamic input layers of anesthetized animals using near-threshold stimuli. Less distinct topography has been described by studies that deviated from the formula above, which brings into question the generality of the principle. Here, we explicitly compared the strength of tonotopic organization at various depths within core and belt regions of the auditory cortex using electrophysiological measurements ranging from single units to delta-band local field potentials (LFP) in the awake and anesthetized mouse. Unit recordings in the middle cortical layers revealed a precise tonotopic organization in core, but not belt, regions of auditory cortex that was similarly robust in awake and anesthetized conditions. In core fields, tonotopy was degraded outside the middle layers or when LFP signals were substituted for unit activity, due to an increasing proportion of recording sites with irregular tuning for pure tones. However, restricting our analysis to clearly defined receptive fields revealed an equivalent tonotopic organization in all layers of the cortical column and for LFP activity ranging from gamma to theta bands. Thus, core fields represent a transition between topographically organized simple receptive field arrangements that extend throughout all layers of the cortical column and the emergence of nontonotopic representations outside the input layers that are further elaborated in the belt fields. PMID:22764225

  9. Robustness of cortical topography across fields, laminae, anesthetic states, and neurophysiological signal types

    PubMed Central

    Guo, Wei; Chambers, Anna R.; Darrow, Keith N.; Hancock, Kenneth E.; Shinn-Cunningham, Barbara G.; Polley, Daniel B.

    2012-01-01

    Topographically organized maps of the sensory receptor epithelia are regarded as cornerstones of cortical organization as well as valuable readouts of diverse biological processes ranging from evolution to neural plasticity. However, maps are most often derived from multiunit activity recorded in the thalamic input layers of anesthetized animals using near-threshold stimuli. Less distinct topography has been described by studies that deviated from the formula above, which brings into question the generality of the principle. Here, we explicitly compared the strength of tonotopic organization at various depths within core and belt regions of the auditory cortex using electrophysiological measurements ranging from single units to delta-band local field potentials (LFP) in the awake and anesthetized mouse. Unit recordings in the middle cortical layers revealed a precise tonotopic organization in core, but not belt, regions of auditory cortex that was similarly robust in awake and anesthetized conditions. In core fields, tonotopy was degraded outside the middle layers or when LFP signals were substituted for unit activity, due to an increasing proportion of recording sites with irregular tuning for pure tones. However, restricting our analysis to clearly defined receptive fields revealed an equivalent tonotopic organization in all layers of the cortical column and for LFP activity ranging from gamma to theta bands. Thus, core fields represent a transition between topographically organized simple receptive field arrangements that extend throughout all layers of the cortical column and the emergence of non-tonotopic representations outside the input layers that are further elaborated in the belt fields. PMID:22764225

  10. The Impact of Cortical Lesions on Thalamo-Cortical Network Dynamics after Acute Ischaemic Stroke: A Combined Experimental and Theoretical Study.

    PubMed

    van Wijngaarden, Joeri B G; Zucca, Riccardo; Finnigan, Simon; Verschure, Paul F M J

    2016-08-01

    The neocortex and thalamus provide a core substrate for perception, cognition, and action, and are interconnected through different direct and indirect pathways that maintain specific dynamics associated with functional states including wakefulness and sleep. It has been shown that a lack of excitation, or enhanced subcortical inhibition, can disrupt this system and drive thalamic nuclei into an attractor state of low-frequency bursting and further entrainment of thalamo-cortical circuits, also called thalamo-cortical dysrhythmia (TCD). The question remains however whether similar TCD-like phenomena can arise with a cortical origin. For instance, in stroke, a cortical lesion could disrupt thalamo-cortical interactions through an attenuation of the excitatory drive onto the thalamus, creating an imbalance between excitation and inhibition that can lead to a state of TCD. Here we tested this hypothesis by comparing the resting-state EEG recordings of acute ischaemic stroke patients (N = 21) with those of healthy, age-matched control-subjects (N = 17). We observed that these patients displayed the hallmarks of TCD: a characteristic downward shift of dominant α-peaks in the EEG power spectra, together with increased power over the lower frequencies (δ and θ-range). Contrary to general observations in TCD, the patients also displayed a broad reduction in β-band activity. In order to explain the genesis of this stroke-induced TCD, we developed a biologically constrained model of a general thalamo-cortical module, allowing us to identify the specific cellular and network mechanisms involved. Our model showed that a lesion in the cortical component leads to sustained cell membrane hyperpolarization in the corresponding thalamic relay neurons, that in turn leads to the de-inactivation of voltage-gated T-type Ca2+-channels, switching neurons from tonic spiking to a pathological bursting regime. This thalamic bursting synchronises activity on a population level through

  11. The Impact of Cortical Lesions on Thalamo-Cortical Network Dynamics after Acute Ischaemic Stroke: A Combined Experimental and Theoretical Study

    PubMed Central

    van Wijngaarden, Joeri B. G.; Finnigan, Simon

    2016-01-01

    The neocortex and thalamus provide a core substrate for perception, cognition, and action, and are interconnected through different direct and indirect pathways that maintain specific dynamics associated with functional states including wakefulness and sleep. It has been shown that a lack of excitation, or enhanced subcortical inhibition, can disrupt this system and drive thalamic nuclei into an attractor state of low-frequency bursting and further entrainment of thalamo-cortical circuits, also called thalamo-cortical dysrhythmia (TCD). The question remains however whether similar TCD-like phenomena can arise with a cortical origin. For instance, in stroke, a cortical lesion could disrupt thalamo-cortical interactions through an attenuation of the excitatory drive onto the thalamus, creating an imbalance between excitation and inhibition that can lead to a state of TCD. Here we tested this hypothesis by comparing the resting-state EEG recordings of acute ischaemic stroke patients (N = 21) with those of healthy, age-matched control-subjects (N = 17). We observed that these patients displayed the hallmarks of TCD: a characteristic downward shift of dominant α-peaks in the EEG power spectra, together with increased power over the lower frequencies (δ and θ-range). Contrary to general observations in TCD, the patients also displayed a broad reduction in β-band activity. In order to explain the genesis of this stroke-induced TCD, we developed a biologically constrained model of a general thalamo-cortical module, allowing us to identify the specific cellular and network mechanisms involved. Our model showed that a lesion in the cortical component leads to sustained cell membrane hyperpolarization in the corresponding thalamic relay neurons, that in turn leads to the de-inactivation of voltage-gated T-type Ca2+-channels, switching neurons from tonic spiking to a pathological bursting regime. This thalamic bursting synchronises activity on a population level through

  12. Cultured Human Renal Cortical Cells

    NASA Technical Reports Server (NTRS)

    1998-01-01

    During the STS-90 shuttle flight in April 1998, cultured renal cortical cells revealed new information about genes. Timothy Hammond, an investigator in NASA's microgravity biotechnology program was interested in culturing kidney tissue to study the expression of proteins useful in the treatment of kidney diseases. Protein expression is linked to the level of differentiation of the kidney cells, and Hammond had difficulty maintaining differentiated cells in vitro. Intrigued by the improvement in cell differentiation that he observed in rat renal cells cultured in NASA's rotating wall vessel (a bioreactor that simulates some aspects of microgravity) and during an experiment performed on the Russian Space Station Mir, Hammond decided to sleuth out which genes were responsible for controlling differentiation of kidney cells. To do this, he compared the gene activity of human renal cells in a variety of gravitational environments, including the microgravity of the space shuttle and the high-gravity environment of a centrifuge. Hammond found that 1,632 genes out of 10,000 analyzed changed their activity level in microgravity, more than in any of the other environments. These results have important implications for kidney research as well as for understanding the basic mechanism for controlling cell differentiation.

  13. Cortical mechanisms of pretense observation.

    PubMed

    Smith, Eric D; Englander, Zoë A; Lillard, Angeline S; Morris, James P

    2013-01-01

    Pretend play emerges in children the world over around 18 months and continues into adolescence and even adulthood. Observing and engaging in pretense are thought to rely on similar neural mechanisms, but little is known about them. Here we examined neural activation patterns associated with observing pretense acts, including high-likelihood, low-likelihood, and imaginary substitute objects, as compared with activation patterns when observing parallel real acts. The association between fantasy predisposition and cortical representations of pretense was also explored. Supporting prior research that used more limited types of pretense, observed pretense acts, when contrasted with real acts, elicited activity in regions associated with mentalizing. A novel contribution here is that substitute object pretense (high- and low-likelihood) elicited significantly more activity than imaginary (pantomime) acts not only in theory of mind regions but also in the superior parietal lobule, a region thought to aid in the prediction and error-monitoring of motor actions. Finally, when high-likelihood pretense acts were contrasted with real acts, participants with elevated fantasy predispositions evidenced significantly different activation patterns than their more reality-prone peers. Future research will explore the intersection of fantasy predisposition and experience with the neural representation of pretense. PMID:23802124

  14. Cortical high-density counterstream architectures.

    PubMed

    Markov, Nikola T; Ercsey-Ravasz, Mária; Van Essen, David C; Knoblauch, Kenneth; Toroczkai, Zoltán; Kennedy, Henry

    2013-11-01

    Small-world networks provide an appealing description of cortical architecture owing to their capacity for integration and segregation combined with an economy of connectivity. Previous reports of low-density interareal graphs and apparent small-world properties are challenged by data that reveal high-density cortical graphs in which economy of connections is achieved by weight heterogeneity and distance-weight correlations. These properties define a model that predicts many binary and weighted features of the cortical network including a core-periphery, a typical feature of self-organizing information processing systems. Feedback and feedforward pathways between areas exhibit a dual counterstream organization, and their integration into local circuits constrains cortical computation. Here, we propose a bow-tie representation of interareal architecture derived from the hierarchical laminar weights of pathways between the high-efficiency dense core and periphery. PMID:24179228

  15. Cortical swallowing processing in early subacute stroke

    PubMed Central

    2011-01-01

    Background Dysphagia is a major complication in hemispheric as well as brainstem stroke patients causing aspiration pneumonia and increased mortality. Little is known about the recovery from dysphagia after stroke. The aim of the present study was to determine the different patterns of cortical swallowing processing in patients with hemispheric and brainstem stroke with and without dysphagia in the early subacute phase. Methods We measured brain activity by mean of whole-head MEG in 37 patients with different stroke localisation 8.2 +/- 4.8 days after stroke to study changes in cortical activation during self-paced swallowing. An age matched group of healthy subjects served as controls. Data were analyzed by means of synthetic aperture magnetometry and group analyses were performed using a permutation test. Results Our results demonstrate strong bilateral reduction of cortical swallowing activation in dysphagic patients with hemispheric stroke. In hemispheric stroke without dysphagia, bilateral activation was found. In the small group of patients with brainstem stroke we observed a reduction of cortical activation and a right hemispheric lateralization. Conclusion Bulbar central pattern generators coordinate the pharyngeal swallowing phase. The observed right hemispheric lateralization in brainstem stroke can therefore be interpreted as acute cortical compensation of subcortically caused dysphagia. The reduction of activation in brainstem stroke patients and dysphagic patients with cortical stroke could be explained in terms of diaschisis. PMID:21392404

  16. Cortical thinning in former professional soccer players.

    PubMed

    Koerte, Inga K; Mayinger, Michael; Muehlmann, Marc; Kaufmann, David; Lin, Alexander P; Steffinger, Denise; Fisch, Barbara; Rauchmann, Boris-Stephan; Immler, Stefanie; Karch, Susanne; Heinen, Florian R; Ertl-Wagner, Birgit; Reiser, Maximilian; Stern, Robert A; Zafonte, Ross; Shenton, Martha E

    2016-09-01

    Soccer is the most popular sport in the world. Soccer players are at high risk for repetitive subconcussive head impact when heading the ball. Whether this leads to long-term alterations of the brain's structure associated with cognitive decline remains unknown. The aim of this study was to evaluate cortical thickness in former professional soccer players using high-resolution structural MR imaging. Fifteen former male professional soccer players (mean age 49.3 [SD 5.1] years) underwent high-resolution structural 3 T MR imaging, as well as cognitive testing. Fifteen male, age-matched former professional non-contact sport athletes (mean age 49.6 [SD 6.4] years) served as controls. Group analyses of cortical thickness were performed using voxel-based statistics. Soccer players demonstrated greater cortical thinning with increasing age compared to controls in the right inferolateral-parietal, temporal, and occipital cortex. Cortical thinning was associated with lower cognitive performance as well as with estimated exposure to repetitive subconcussive head impact. Neurocognitive evaluation revealed decreased memory performance in the soccer players compared to controls. The association of cortical thinning and decreased cognitive performance, as well as exposure to repetitive subconcussive head impact, further supports the hypothesis that repetitive subconcussive head impact may play a role in early cognitive decline in soccer players. Future studies are needed to elucidate the time course of changes in cortical thickness as well as their association with impaired cognitive function and possible underlying neurodegenerative process. PMID:26286826

  17. CD Recorders.

    ERIC Educational Resources Information Center

    Falk, Howard

    1998-01-01

    Discussion of CD (compact disc) recorders describes recording applications, including storing large graphic files, creating audio CDs, and storing material downloaded from the Internet; backing up files; lifespan; CD recording formats; continuous recording; recording software; recorder media; vulnerability of CDs; basic computer requirements; and…

  18. Cortical mechanisms of smooth eye movements revealed by dynamic covariations of neural and behavioral responses.

    PubMed

    Schoppik, David; Nagel, Katherine I; Lisberger, Stephen G

    2008-04-24

    Neural activity in the frontal eye fields controls smooth pursuit eye movements, but the relationship between single neuron responses, cortical population responses, and eye movements is not well understood. We describe an approach to dynamically link trial-to-trial fluctuations in neural responses to parallel variations in pursuit and demonstrate that individual neurons predict eye velocity fluctuations at particular moments during the course of behavior, while the population of neurons collectively tiles the entire duration of the movement. The analysis also reveals the strength of correlations in the eye movement predictions derived from pairs of simultaneously recorded neurons and suggests a simple model of cortical processing. These findings constrain the primate cortical code for movement, suggesting that either a few neurons are sufficient to drive pursuit at any given time or that many neurons operate collectively at each moment with remarkably little variation added to motor command signals downstream from the cortex. PMID:18439409

  19. Hierarchical and serial processing in the spatial auditory cortical pathway is degraded by natural aging

    PubMed Central

    Juarez-Salinas, Dina L.; Engle, James R.; Navarro, Xochi O.; Recanzone, Gregg H.

    2010-01-01

    The compromised abilities to localize sounds and to understand speech are two hallmark deficits in aged individuals. The auditory cortex is necessary for these processes, yet we know little about how normal aging affects these early cortical fields. In this study, we recorded the spatial tuning of single neurons in primary (area A1) and secondary (area CL) auditory cortical areas in young and aged alert rhesus macaques. We found that the neurons of aged animals had greater spontaneous and driven activity, and broader spatial tuning compared to those of younger animals. Importantly, spatial tuning was not sharpened between A1 and CL in aged monkeys as it is in younger monkeys. This implies that a major effect of normal aging is a degradation of the hierarchical processing between serially connected cortical areas, which could be a key contributing mechanism of the general cognitive decline that is commonly observed in normal aging. PMID:21048138

  20. Cortical representation of spatiotemporal pattern of firing evoked by echolocation signals: population encoding of target features in real time.

    PubMed

    Palakal, M J; Wong, D

    1999-07-01

    Target perception in echolocating bats entails the generation of an acoustic image of the target in the auditory cortex. By integrating information conveyed in the sequence of acoustic echoes, the population of cortical neurons in hypothesized to encode different target features based on its spatiotemporal pattern of neural-spike firing during the course of echolocation. A biologically plausible approach to the cortical representation of target features is employed by using electrophysiological data recorded from the auditory cortex of the FM bat, Myotis lucifugus. A single-neuron model of delay-sensitive neurons is first approximated by the formulation of a Gaussian function with different variables to represent the delay-tuning properties of individual cortical neurons. A cortical region consisting of delay-sensitive neurons organized topographically according to best frequency (i.e., tontopically organized) is then modeled with multiple layers of the single-neuron model. A mechanism is developed to represent and encode the responses of these neurons based on time-dependent, incoming echo signals. The time-varying responses of the population of neurons are mapped spatially on the auditory-cortical surface as a cortical response map (CORMAP). The model is tested using phantom targets with single and multiple glints. These simulation results provide further validation of the current auditory framework as a biomimetic mechanism for capturing time-varying, acoustic stimuli impinging in the bat's ears, and the neural representation of acoustic stimulus features by saptiotemporal-firing patterns in the cortical population. PMID:10420638

  1. Reduced modulation of scanpaths in response to task demands in posterior cortical atrophy.

    PubMed

    Shakespeare, Timothy J; Pertzov, Yoni; Yong, Keir X X; Nicholas, Jennifer; Crutch, Sebastian J

    2015-02-01

    A difficulty in perceiving visual scenes is one of the most striking impairments experienced by patients with the clinico-radiological syndrome posterior cortical atrophy (PCA). However whilst a number of studies have investigated perception of relatively simple experimental stimuli in these individuals, little is known about multiple object and complex scene perception and the role of eye movements in posterior cortical atrophy. We embrace the distinction between high-level (top-down) and low-level (bottom-up) influences upon scanning eye movements when looking at scenes. This distinction was inspired by Yarbus (1967), who demonstrated how the location of our fixations is affected by task instructions and not only the stimulus' low level properties. We therefore examined how scanning patterns are influenced by task instructions and low-level visual properties in 7 patients with posterior cortical atrophy, 8 patients with typical Alzheimer's disease, and 19 healthy age-matched controls. Each participant viewed 10 scenes under four task conditions (encoding, recognition, search and description) whilst eye movements were recorded. The results reveal significant differences between groups in the impact of test instructions upon scanpaths. Across tasks without a search component, posterior cortical atrophy patients were significantly less consistent than typical Alzheimer's disease patients and controls in where they were looking. By contrast, when comparing search and non-search tasks, it was controls who exhibited lowest between-task similarity ratings, suggesting they were better able than posterior cortical atrophy or typical Alzheimer's disease patients to respond appropriately to high-level needs by looking at task-relevant regions of a scene. Posterior cortical atrophy patients had a significant tendency to fixate upon more low-level salient parts of the scenes than controls irrespective of the viewing task. The study provides a detailed characterisation of

  2. Motor Cortical Plasticity to Training Started in Childhood: The Example of Piano Players.

    PubMed

    Chieffo, Raffaella; Straffi, Laura; Inuggi, Alberto; Gonzalez-Rosa, Javier J; Spagnolo, Francesca; Coppi, Elisabetta; Nuara, Arturo; Houdayer, Elise; Comi, Giancarlo; Leocani, Letizia

    2016-01-01

    Converging evidence suggest that motor training is associated with early and late changes of the cortical motor system. Transcranial magnetic stimulation (TMS) offers the possibility to study plastic rearrangements of the motor system in physiological and pathological conditions. We used TMS to characterize long-term changes in upper limb motor cortical representation and interhemispheric inhibition associated with bimanual skill training in pianists who started playing in an early age. Ipsilateral silent period (iSP) and cortical TMS mapping of hand muscles were obtained from 30 strictly right-handed subjects (16 pianists, 14 naïve controls), together with electromyographic recording of mirror movements (MMs) to voluntary hand movements. In controls, motor cortical representation of hand muscles was larger on the dominant (DH) than on the non-dominant hemisphere (NDH). On the contrary, pianists showed symmetric cortical output maps, being their DH less represented than in controls. In naïve subjects, the iSP was smaller on the right vs left abductor pollicis brevis (APB) indicating a weaker inhibition from the NDH to the DH. In pianists, interhemispheric inhibition was more symmetric as their DH was better inhibited than in controls. Electromyographic MMs were observed only in naïve subjects (7/14) and only to voluntary movement of the non-dominant hand. Subjects with MM had a lower iSP area on the right APB compared with all the others. Our findings suggest a more symmetrical motor cortex organization in pianists, both in terms of muscle cortical representation and interhemispheric inhibition. Although we cannot disentangle training-related from preexisting conditions, it is possible that long-term bimanual practice may reshape motor cortical representation and rebalance interhemispheric interactions, which in naïve right-handed subjects would both tend to favour the dominant hemisphere. PMID:27336584

  3. Motor Cortical Plasticity to Training Started in Childhood: The Example of Piano Players

    PubMed Central

    Inuggi, Alberto; Gonzalez-Rosa, Javier J.; Spagnolo, Francesca; Coppi, Elisabetta; Nuara, Arturo; Houdayer, Elise; Comi, Giancarlo; Leocani, Letizia

    2016-01-01

    Converging evidence suggest that motor training is associated with early and late changes of the cortical motor system. Transcranial magnetic stimulation (TMS) offers the possibility to study plastic rearrangements of the motor system in physiological and pathological conditions. We used TMS to characterize long-term changes in upper limb motor cortical representation and interhemispheric inhibition associated with bimanual skill training in pianists who started playing in an early age. Ipsilateral silent period (iSP) and cortical TMS mapping of hand muscles were obtained from 30 strictly right-handed subjects (16 pianists, 14 naïve controls), together with electromyographic recording of mirror movements (MMs) to voluntary hand movements. In controls, motor cortical representation of hand muscles was larger on the dominant (DH) than on the non-dominant hemisphere (NDH). On the contrary, pianists showed symmetric cortical output maps, being their DH less represented than in controls. In naïve subjects, the iSP was smaller on the right vs left abductor pollicis brevis (APB) indicating a weaker inhibition from the NDH to the DH. In pianists, interhemispheric inhibition was more symmetric as their DH was better inhibited than in controls. Electromyographic MMs were observed only in naïve subjects (7/14) and only to voluntary movement of the non-dominant hand. Subjects with MM had a lower iSP area on the right APB compared with all the others. Our findings suggest a more symmetrical motor cortex organization in pianists, both in terms of muscle cortical representation and interhemispheric inhibition. Although we cannot disentangle training-related from preexisting conditions, it is possible that long-term bimanual practice may reshape motor cortical representation and rebalance interhemispheric interactions, which in naïve right-handed subjects would both tend to favour the dominant hemisphere. PMID:27336584

  4. Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?

    PubMed Central

    Evangelista, Elisa; Bénar, Christian; Bonini, Francesca; Carron, Romain; Colombet, Bruno; Régis, Jean; Bartolomei, Fabrice

    2015-01-01

    The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from 10 patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings [stereoelectroencephalography (SEEG)]. We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and cortical regions. Then, we derived synchronization indices, namely global, thalamic, mesio-temporal, and thalamo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic “outputs and inputs” connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic synchronization index was significantly more elevated at the end of seizure than at the onset. The global synchronization index at the end of seizure negatively correlated with seizure duration (p = 0.045) and in the same way the thalamic synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-cortical spike-and-wave pattern at the end. They were associated to higher values of all synchronization indices and outputs from thalamus (p = 0.0079). SWP seizures displayed a higher and sustained increase of cortical and thalamo-cortical synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-cortical oscillations might contribute to seizure termination via modulation of cortical synchronization. In the subgroup of SWP seizures, thalamus may exert a control on temporal lobe structures by inducing a stable hypersynchronization that ultimately leads to seizure termination. PMID:26388834

  5. Diffuse malformations of cortical development.

    PubMed

    Bahi-Buisson, Nadia; Guerrini, Renzo

    2013-01-01

    Malformations of cortical development (MCD) represent a major cause of developmental disabilities and severe epilepsy. Advances in imaging and genetics have improved the diagnosis and classification of these conditions. Up to now, eight genes have been involved in different types of MCD. Lissencephaly-pachygyria and subcortical band heterotopia (SBH) represent a malformative spectrum resulting from mutations of either LIS1 or DCX genes. LIS1 mutations cause a more severe malformation in the posterior brain regions. DCX mutations usually cause anteriorly predominant lissencephaly in males and SBH in female patients. Additional forms are X-linked lissencephaly with corpus callosum agenesis and ambiguous genitalia associated with mutations of the ARX gene. Lissencephaly with cerebellar hypoplasia (LCH) encompass heterogeneous disorders named LCH types a to d. LCHa is related to mutation in LIS1 or DCX, LCHb with mutation of the RELN gene, and LCHd could be related to the TUBA1A gene. Polymicrogyria encompasses a wide range of clinical, etiological, and histological findings. Among several syndromes, recessive bilateral fronto-parietal polymicrogyria has been associated with mutations of the GPR56 gene. Bilateral perisylvian polymicrogyria has been associated with mutations in the SRPX2 gene in a few individuals and with linkage to chromosome Xq28 in a some other families. X-linked bilateral periventricular nodular heterotopia (PNH) consists of PNH with focal epilepsy in females and prenatal lethality in males. Filamin A (FLNA) mutations have been reported in some families and in sporadic patients. It is possible to infer the most likely causative gene by brain imaging studies and other clinical findings. PMID:23622213

  6. Cortical mechanisms of cocaine sensitization.

    PubMed

    Steketee, Jeffery D

    2005-01-01

    Behavioral sensitization is the augmented motor-stimulant response that occurs with repeated, intermittent exposure to most drugs of abuse, including cocaine. Sensitization, which is a long-lasting phenomenon, is thought to underlie drug craving and relapse to drug use. Much research has been conducted to determine the neural mechanisms of sensitization. The bulk of this effort has focused on the nucleus accumbens and ventral tegmental area (VTA) that comprise a portion of the mesolimbic dopamine system. Recently, studies have begun to also explore the role of the medial prefrontal cortex (mPFC) in sensitization, in part because this region provides glutamatergic innervation to the VTA and nucleus accumbens. The present review will coalesce these studies into a working hypothesis that states that cocaine sensitization results from a decrease in inhibitory modulation of excitatory transmission from the mPFC to the VTA and nucleus accumbens. The discussion will revolve around how repeated cocaine exposure alters dopamine, gamma-aminobutyric acid (GABA), and glutamate regulation of pyramidal cell activity. It will be proposed that cocaine-induced alterations in cortical transmission occur in two phases. During early withdrawal from repeated cocaine exposure, changes in neurotransmitter release are thought to underlie the decreased inhibitory modulation of pyramidal projection neurons. Following more prolonged withdrawal, the attenuation in inhibitory transmission appears to occur at the receptor level. A model will be presented that may serve to direct future studies on the involvement of the mPFC in the development of cocaine sensitization, which ultimately could lead to development of pharmacotherapies for cocaine addiction. PMID:16808728

  7. Awake vs. anesthetized: layer-specific sensory processing in visual cortex and functional connectivity between cortical areas

    PubMed Central

    Sellers, Kristin K.; Bennett, Davis V.; Hutt, Axel; Williams, James H.

    2015-01-01

    During general anesthesia, global brain activity and behavioral state are profoundly altered. Yet it remains mostly unknown how anesthetics alter sensory processing across cortical layers and modulate functional cortico-cortical connectivity. To address this gap in knowledge of the micro- and mesoscale effects of anesthetics on sensory processing in the cortical microcircuit, we recorded multiunit activity and local field potential in awake and anesthetized ferrets (Mustela putoris furo) during sensory stimulation. To understand how anesthetics alter sensory processing in a primary sensory area and the representation of sensory input in higher-order association areas, we studied the local sensory responses and long-range functional connectivity of primary visual cortex (V1) and prefrontal cortex (PFC). Isoflurane combined with xylazine provided general anesthesia for all anesthetized recordings. We found that anesthetics altered the duration of sensory-evoked responses, disrupted the response dynamics across cortical layers, suppressed both multimodal interactions in V1 and sensory responses in PFC, and reduced functional cortico-cortical connectivity between V1 and PFC. Together, the present findings demonstrate altered sensory responses and impaired functional network connectivity during anesthesia at the level of multiunit activity and local field potential across cortical layers. PMID:25833839

  8. Awake vs. anesthetized: layer-specific sensory processing in visual cortex and functional connectivity between cortical areas.

    PubMed

    Sellers, Kristin K; Bennett, Davis V; Hutt, Axel; Williams, James H; Fröhlich, Flavio

    2015-06-01

    During general anesthesia, global brain activity and behavioral state are profoundly altered. Yet it remains mostly unknown how anesthetics alter sensory processing across cortical layers and modulate functional cortico-cortical connectivity. To address this gap in knowledge of the micro- and mesoscale effects of anesthetics on sensory processing in the cortical microcircuit, we recorded multiunit activity and local field potential in awake and anesthetized ferrets (Mustela putoris furo) during sensory stimulation. To understand how anesthetics alter sensory processing in a primary sensory area and the representation of sensory input in higher-order association areas, we studied the local sensory responses and long-range functional connectivity of primary visual cortex (V1) and prefrontal cortex (PFC). Isoflurane combined with xylazine provided general anesthesia for all anesthetized recordings. We found that anesthetics altered the duration of sensory-evoked responses, disrupted the response dynamics across cortical layers, suppressed both multimodal interactions in V1 and sensory responses in PFC, and reduced functional cortico-cortical connectivity between V1 and PFC. Together, the present findings demonstrate altered sensory responses and impaired functional network connectivity during anesthesia at the level of multiunit activity and local field potential across cortical layers. PMID:25833839

  9. Epidural cortical stimulation and aphasia therapy

    PubMed Central

    Cherney, Leora R.; Harvey, Richard L.; Babbitt, Edna M.; Hurwitz, Rosalind; Kaye, Rosalind C.; Lee, Jaime B.; Small, Steven. L.

    2013-01-01

    Background There are several methods of delivering cortical brain stimulation to modulate cortical excitability and interest in their application as an adjuvant strategy in aphasia rehabilitation after stroke is growing. Epidural cortical stimulation, although more invasive than other methods, permits high frequency stimulation of high spatial specificity to targeted neuronal populations. Aims First, we review evidence supporting the use of epidural cortical stimulation for upper limb recovery after focal cortical injury in both animal models and human stroke survivors. These data provide the empirical and theoretical platform underlying the use of epidural cortical stimulation in aphasia. Second, we summarize evidence for the application of epidural cortical stimulation in aphasia. We describe the procedures and primary outcomes of a safety and feasibility study (Cherney, Erickson & Small, 2010), and provide previously unpublished data regarding secondary behavioral outcomes from that study. Main Contribution In a controlled study comparing epidural cortical stimulation plus language treatment (CS/LT) to language treatment alone (LT), eight stroke survivors with nonfluent aphasia received intensive language therapy for 6 weeks. Four of these participants also underwent surgical implantation of an epidural stimulation device which was activated only during therapy sessions. Behavioral data were collected before treatment, immediately after treatment, and at 6 and 12 weeks following the end of treatment. The effect size for the primary outcome measure, the Western Aphasia Battery Aphasia Quotient, was benchmarked as moderate from baseline to immediately post-treatment, and large from baseline to the 12-week follow-up. Similarly, effect sizes obtained at the 12-week follow-up for the Boston Naming Test, the Communicative Effectiveness Index, and for correct information units on a picture description task were greater than those obtained immediately post treatment

  10. Abnormal Cortical Development after Premature Birth Shown by Altered Allometric Scaling of Brain Growth

    PubMed Central

    Kapellou, Olga; Counsell, Serena J; Kennea, Nigel; Dyet, Leigh; Saeed, Nadeem; Stark, Jaroslav; Maalouf, Elia; Duggan, Philip; Ajayi-Obe, Morenike; Hajnal, Jo; Allsop, Joanna M; Boardman, James; Rutherford, Mary A; Cowan, Frances; Edwards, A. David

    2006-01-01

    Background We postulated that during ontogenesis cortical surface area and cerebral volume are related by a scaling law whose exponent gives a quantitative measure of cortical development. We used this approach to investigate the hypothesis that premature termination of the intrauterine environment by preterm birth reduces cortical development in a dose-dependent manner, providing a neural substrate for functional impairment. Methods and Findings We analyzed 274 magnetic resonance images that recorded brain growth from 23 to 48 wk of gestation in 113 extremely preterm infants born at 22 to 29 wk of gestation, 63 of whom underwent neurodevelopmental assessment at a median age of 2 y. Cortical surface area was related to cerebral volume by a scaling law with an exponent of 1.29 (95% confidence interval, 1.25–1.33), which was proportional to later neurodevelopmental impairment. Increasing prematurity and male gender were associated with a lower scaling exponent (p < 0.0001) independent of intrauterine or postnatal somatic growth. Conclusions Human brain growth obeys an allometric scaling relation that is disrupted by preterm birth in a dose-dependent, sexually dimorphic fashion that directly parallels the incidence of neurodevelopmental impairments in preterm infants. This result focuses attention on brain growth and cortical development during the weeks following preterm delivery as a neural substrate for neurodevelopmental impairment after premature delivery. PMID:16866579

  11. Human cortical responses to slow and fast binaural beats reveal multiple mechanisms of binaural hearing.

    PubMed

    Ross, Bernhard; Miyazaki, Takahiro; Thompson, Jessica; Jamali, Shahab; Fujioka, Takako

    2014-10-15

    When two tones with slightly different frequencies are presented to both ears, they interact in the central auditory system and induce the sensation of a beating sound. At low difference frequencies, we perceive a single sound, which is moving across the head between the left and right ears. The percept changes to loudness fluctuation, roughness, and pitch with increasing beat rate. To examine the neural representations underlying these different perceptions, we recorded neuromagnetic cortical responses while participants listened to binaural beats at a continuously varying rate between 3 Hz and 60 Hz. Binaural beat responses were analyzed as neuromagnetic oscillations following the trajectory of the stimulus rate. Responses were largest in the 40-Hz gamma range and at low frequencies. Binaural beat responses at 3 Hz showed opposite polarity in the left and right auditory cortices. We suggest that this difference in polarity reflects the opponent neural population code for representing sound location. Binaural beats at any rate induced gamma oscillations. However, the responses were largest at 40-Hz stimulation. We propose that the neuromagnetic gamma oscillations reflect postsynaptic modulation that allows for precise timing of cortical neural firing. Systematic phase differences between bilateral responses suggest that separate sound representations of a sound object exist in the left and right auditory cortices. We conclude that binaural processing at the cortical level occurs with the same temporal acuity as monaural processing whereas the identification of sound location requires further interpretation and is limited by the rate of object representations. PMID:25008412

  12. Altered Resting-State Cortical EEG Oscillations in Patients With Severe Asymptomatic Carotid Stenosis.

    PubMed

    Hsiao, Fu-Jung; Hsieh, Fang-Yuh; Chen, Wei-Ta; Chu, Da-Chen; Lin, Yung-Yang

    2016-04-01

    Asymptomatic carotid stenosis is characterized by altered cerebral hemodynamics and cognitive impairment, but the underlying neurophysiological mechanism remains unclear. To elucidate the alterations of cortical activities, resting-state electrophysiological activities were recorded from patients with mild (<30%; n=10; age 57-85 years), moderate (30% to 50%; n=11; age 66-88 years), and severe (>50%; n=8; age 67-91 years) carotid stenosis. The current density and oscillatory power of the cortical sources were analyzed using the minimum norm estimates method combined with fast Fourier transform analysis. Our results indicate that the cortical current density among regions of the brain was similar, irrespective of the degree of carotid stenosis. With regard to the cortical oscillations, augmented theta activities in the bilateral parietal, left temporal, and left occipital regions and attenuated alpha activities in the bilateral frontal and right central regions were obtained in patients with severe asymptomatic carotid stenosis. We suggest that the source-based cortical oscillations at theta and alpha bands might reflect the alterations of the brain activities and characterize the altered neurophysiological mechanism of the brain with at least 50% occlusion of the carotid artery. Further longitudinal studies with larger populations are warranted to verify the present findings. PMID:25465434

  13. Stability of muscle synergies for voluntary actions after cortical stroke in humans

    PubMed Central

    Cheung, Vincent C. K.; Piron, Lamberto; Agostini, Michela; Silvoni, Stefano; Turolla, Andrea; Bizzi, Emilio

    2009-01-01

    Production of voluntary movements relies critically on the functional integration of several motor cortical areas, such as the primary motor cortex, and the spinal circuitries. Surprisingly, after almost 40 years of research, how the motor cortices specify descending neural signals destined for the downstream interneurons and motoneurons has remained elusive. In light of the many recent experimental demonstrations that the motor system may coordinate muscle activations through a linear combination of muscle synergies, we hypothesize that the motor cortices may function to select and activate fixed muscle synergies specified by the spinal or brainstem networks. To test this hypothesis, we recorded electromyograms (EMGs) from 12–16 upper arm and shoulder muscles from both the unaffected and the stroke-affected arms of stroke patients having moderate-to-severe unilateral ischemic lesions in the frontal motor cortical areas. Analyses of EMGs using a nonnegative matrix factorization algorithm revealed that in seven of eight patients the muscular compositions of the synergies for both the unaffected and the affected arms were strikingly similar to each other despite differences in motor performance between the arms, and differences in cerebral lesion sizes and locations between patients. This robustness of muscle synergies that we observed supports the notion that descending cortical signals represent neuronal drives that select, activate, and flexibly combine muscle synergies specified by networks in the spinal cord and/or brainstem. Our conclusion also suggests an approach to stroke rehabilitation by focusing on those synergies with altered activations after stroke. PMID:19880747

  14. Thalamic Responses to Nociceptive-Specific Input in Humans: Functional Dichotomies and Thalamo-Cortical Connectivity.

    PubMed

    Bastuji, Hélène; Frot, Maud; Mazza, Stéphanie; Perchet, Caroline; Magnin, Michel; Garcia-Larrea, Luis

    2016-06-01

    While nociceptive cortical activation is now well characterized in humans, understanding of the nociceptive thalamus remains largely fragmentary. We used laser stimuli and intracerebral electrodes in 17 human subjects to record nociceptive-specific field responses in 4 human thalamic nuclei and a number of cortical areas. Three nuclei known to receive spinothalamic (STT) projections in primates (ventro-postero-lateral [VPL], anterior pulvinar [PuA], and central lateral [CL]) exhibited responses with similar latency, indicating their parallel activation by nociceptive afferents. Phase coherence analysis, however, revealed major differences in their functional connectivity: while VPL and PuA drove a limited set of cortical targets, CL activities were synchronized with a large network including temporal, parietal, and frontal areas. Our data suggest that STT afferents reach simultaneously a set of lateral and medial thalamic regions unconstrained by traditional nuclear borders. The broad pattern of associated cortical networks suggests that a single nociceptive volley is able to trigger the sensory, cognitive, and emotional activities that underlie the complex pain experience. The medial pulvinar, an associative nucleus devoid of STT input, exhibited delayed responses suggesting its dependence on descending cortico-thalamic projections. Its widespread cortical connectivity suggests a role in synchronizing parietal, temporal, and frontal activities, hence contributing to the access of noxious input to conscious awareness. PMID:25994963

  15. Integrated Mechanisms of Anticipation and Rate-of-Change Computations in Cortical Circuits

    PubMed Central

    Puccini, Gabriel D; Sanchez-Vives, Maria V; Compte, Albert

    2007-01-01

    Local neocortical circuits are characterized by stereotypical physiological and structural features that subserve generic computational operations. These basic computations of the cortical microcircuit emerge through the interplay of neuronal connectivity, cellular intrinsic properties, and synaptic plasticity dynamics. How these interacting mechanisms generate specific computational operations in the cortical circuit remains largely unknown. Here, we identify the neurophysiological basis of both the rate of change and anticipation computations on synaptic inputs in a cortical circuit. Through biophysically realistic computer simulations and neuronal recordings, we show that the rate-of-change computation is operated robustly in cortical networks through the combination of two ubiquitous brain mechanisms: short-term synaptic depression and spike-frequency adaptation. We then show how this rate-of-change circuit can be embedded in a convergently connected network to anticipate temporally incoming synaptic inputs, in quantitative agreement with experimental findings on anticipatory responses to moving stimuli in the primary visual cortex. Given the robustness of the mechanism and the widespread nature of the physiological machinery involved, we suggest that rate-of-change computation and temporal anticipation are principal, hard-wired functions of neural information processing in the cortical microcircuit. PMID:17500584

  16. Thalamocortical Connections of Parietal Somatosensory Cortical Fields in Macaque Monkeys are Highly Divergent and Convergent

    PubMed Central

    Padberg, Jeffrey; Cerkevich, Christina; Engle, James; Rajan, Alexander T.; Recanzone, Gregg; Kaas, Jon

    2009-01-01

    We examined the organization and cortical projections of the somatosensory thalamus using multiunit microelectrode recording techniques in anesthetized monkeys combined with neuroanatomical tracings techniques and architectonic analysis. Different portions of the hand representation in area 3b were injected with different anatomical tracers in the same animal, or matched body part representations in parietal areas 3a, 3b, 1, 2, and areas 2 and 5 were injected with different anatomical tracers in the same animal to directly compare their thalamocortical connections. We found that the somatosensory thalamus is composed of several representations of cutaneous and deep receptors of the contralateral body. These nuclei include the ventral posterior nucleus, the ventral posterior superior nucleus, the ventral posterior inferior nucleus, and the ventral lateral nucleus. Each nucleus projects to several different cortical fields, and each cortical field receives projections from multiple thalamic nuclei. In contrast to other sensory systems, each of these somatosensory cortical fields is uniquely innervated by multiple thalamic nuclei. These data indicate that multiple inputs are processed simultaneously within and across several, “hierarchically connected” cortical fields. PMID:19221145

  17. Reduced variability of ongoing and evoked cortical activity leads to improved behavioral performance.

    PubMed

    Ledberg, Anders; Montagnini, Anna; Coppola, Richard; Bressler, Steven L

    2012-01-01

    Sensory responses of the brain are known to be highly variable, but the origin and functional relevance of this variability have long remained enigmatic. Using the variable foreperiod of a visual discrimination task to assess variability in the primate cerebral cortex, we report that visual evoked response variability is not only tied to variability in ongoing cortical activity, but also predicts mean response time. We used cortical local field potentials, simultaneously recorded from widespread cortical areas, to gauge both ongoing and visually evoked activity. Trial-to-trial variability of sensory evoked responses was strongly modulated by foreperiod duration and correlated both with the cortical variability before stimulus onset as well as with response times. In a separate set of experiments we probed the relation between small saccadic eye movements, foreperiod duration and manual response times. The rate of eye movements was modulated by foreperiod duration and eye position variability was positively correlated with response times. Our results indicate that when the time of a sensory stimulus is predictable, reduction in cortical variability before the stimulus can improve normal behavioral function that depends on the stimulus. PMID:22937021

  18. Natural stimuli from three coherent modalities enhance behavioral responses and electrophysiological cortical activity in humans.

    PubMed

    Sella, Irit; Reiner, Miriam; Pratt, Hillel

    2014-07-01

    Cues that involve a number of sensory modalities are processed in the brain in an interactive multimodal manner rather than independently for each modality. We studied multimodal integration in a natural, yet fully controlled scene, implemented as an interactive game in an auditory-haptic-visual virtual environment. In this imitation of a natural scene, the targets of perception were ecologically valid uni-, bi- and tri-modal manifestations of a simple event-a ball hitting a wall. Subjects were engaged in the game while their behavioral and early cortical electrophysiological responses were measured. Behavioral results confirmed that tri-modal cues were detected faster and more accurately than bi-modal cues, which, likewise, showed advantages over unimodal responses. Event-Related Potentials (ERPs) were recorded, and the first 200 ms following stimulus onset was analyzed to reveal the latencies of cortical multimodal interactions as estimated by sLORETA. These electrophysiological findings indicated bi-modal as well as tri-modal interactions beginning very early (~30 ms), uniquely for each multimodal combination. The results suggest that early cortical multimodal integration accelerates cortical activity and, in turn, enhances performance measures. This acceleration registers on the scalp as sub-additive cortical activation. PMID:24315926

  19. EEG during pedaling: Evidence for cortical control of locomotor tasks

    PubMed Central

    Jain, Sanket; Gourab, Krishnaj; Schindler-Ivens, Sheila; Schmit, Brian D.

    2014-01-01

    Objective This study characterized the brain electrical activity during pedaling, a locomotor-like task, in humans. We postulated that phasic brain activity would be associated with active pedaling, consistent with a cortical role in locomotor tasks. Methods Sixty four channels of electroencephalogram (EEG) and 10 channels of electromyogram (EMG) data were recorded from 10 neurologically-intact volunteers while they performed active and passive (no effort) pedaling on a custom-designed stationary bicycle. Ensemble averaged waveforms, 2 dimensional topographic maps and amplitude of the β (13–35 Hz) frequency band were analyzed and compared between active and passive trials. Results The peak-to-peak amplitude (peak positive–peak negative) of the EEG waveform recorded at the Cz electrode was higher in the passive than the active trials (p < 0.01). β-band oscillations in electrodes overlying the leg representation area of the cortex were significantly desynchronized during active compared to the passive pedaling (p < 0.01). A significant negative correlation was observed between the average EEG waveform for active trials and the composite EMG (summated EMG from both limbs for each muscle) of the rectus femoris (r = −0.77, p < 0.01) the medial hamstrings (r = −0.85, p < 0.01) and the tibialis anterior (r = −0.70, p < 0.01) muscles. Conclusions These results demonstrated that substantial sensorimotor processing occurs in the brain during pedaling in humans. Further, cortical activity seemed to be greatest during recruitment of the muscles critical for transitioning the legs from flexion to extension and vice versa. Significance This is the first study demonstrating the feasibility of EEG recording during pedaling, and owing to similarities between pedaling and bipedal walking, may provide valuable insight into brain activity during locomotion in humans. PMID:23036179

  20. Effects of Tongue Force Training on Orolingual Motor Cortical Representation

    PubMed Central

    Guggenmos, David J.; Barbay, Scott; Bethel-Brown, Crystal; Nudo, Randolph J.; Stanford, John A.

    2009-01-01

    Previous research has demonstrated that training rats in a skilled reaching condition will induce task-related changes in the caudal forelimb area of motor cortex. The purpose of the present study was to determine whether task-specific changes can be induced within the orofacial area of the motor cortex in rats. Specifically, we compared changes of the orofacial motor cortical representation in lick-trained rats to age-matched controls. For one month, six water-restricted Sprague-Dawley rats were trained to lick an isometric force-sensing disc at increasing forces for water reinforcement. The rats were trained daily for six minutes starting with forces of 1g, and increasing over the course of the month to 10, 15, 20, 25 and finally 30 g. One to three days following the last training session, the animals were subjected to a neurophysiological motor mapping procedure in which motor representations corresponding to the orofacial and adjacent areas were defined using intracortical microstimulation (ICMS) techniques. We found no statistical difference in the topographical representation of the control (mean = 2.03 mm2) vs. trained (1.87 mm2) rats. This result indicates that force training alone is insufficient to drive changes in the size of the cortical representation. We also recorded the minimum current threshold required to elicit a motor response at each site of microstimulation. We found that the lick-trained rats had a significantly lower average minimum threshold (29.1 ± 1.0 μA) for evoking movements related to the task compared to control rats (34.6 ± 1.1 μA). These results indicate that while tongue force training alone does not produce lasting changes in the size of the orofacial cortical motor representation, tongue force training decreases the current thresholds necessary for eliciting an ICMS-evoked motor response. PMID:19428638

  1. Visual-induced expectations modulate auditory cortical responses

    PubMed Central

    van Wassenhove, Virginie; Grzeczkowski, Lukasz

    2015-01-01

    Active sensing has important consequences on multisensory processing (Schroeder et al., 2010). Here, we asked whether in the absence of saccades, the position of the eyes and the timing of transient color changes of visual stimuli could selectively affect the excitability of auditory cortex by predicting the “where” and the “when” of a sound, respectively. Human participants were recorded with magnetoencephalography (MEG) while maintaining the position of their eyes on the left, right, or center of the screen. Participants counted color changes of the fixation cross while neglecting sounds which could be presented to the left, right, or both ears. First, clear alpha power increases were observed in auditory cortices, consistent with participants' attention directed to visual inputs. Second, color changes elicited robust modulations of auditory cortex responses (“when” prediction) seen as ramping activity, early alpha phase-locked responses, and enhanced high-gamma band responses in the contralateral side of sound presentation. Third, no modulations of auditory evoked or oscillatory activity were found to be specific to eye position. Altogether, our results suggest that visual transience can automatically elicit a prediction of “when” a sound will occur by changing the excitability of auditory cortices irrespective of the attended modality, eye position or spatial congruency of auditory and visual events. To the contrary, auditory cortical responses were not significantly affected by eye position suggesting that “where” predictions may require active sensing or saccadic reset to modulate auditory cortex responses, notably in the absence of spatial orientation to sounds. PMID:25705174

  2. Regional Patterns of Cortical Phase Synchrony in the Resting State.

    PubMed

    Casimo, Kaitlyn; Darvas, Felix; Wander, Jeremiah; Ko, Andrew; Grabowski, Thomas J; Novotny, Edward; Poliakov, Andrew; Ojemann, Jeffrey G; Weaver, Kurt E

    2016-07-01

    Synchronized phase estimates between oscillating neuronal signals at the macroscale level reflect coordinated activities between neuronal assemblies. Recent electrophysiological evidence suggests the presence of significant spontaneous phase synchrony within the resting state. The purpose of this study was to investigate phase synchrony, including directional interactions, in resting state subdural electrocorticographic recordings to better characterize patterns of regional phase interactions across the lateral cortical surface during the resting state. We estimated spontaneous phase locking value (PLV) as a measure of functional connectivity, and phase slope index (PSI) as a measure of pseudo-causal phase interactions, across a broad range of canonical frequency bands and the modulation of the amplitude envelope of high gamma (amHG), a band that is believed to best reflect the physiological processes giving rise to the functional magnetic resonance imaging BOLD signal. Long-distance interactions had higher PLVs in slower frequencies (≤theta) than in higher ones (≥beta) with amHG behaving more like slow frequencies, and a general trend of increasing frequency band of significant PLVs when moving across the lateral surface along an anterior-posterior axis. Moreover, there was a strong trend of frontal-to-parietal directional phase synchronization, measured by PSI across multiple frequencies. These findings, which are likely indicative of coordinated and structured spontaneous cortical interactions, are important in the study of time scales and directional nature of resting state functional connectivity, and may ultimately contribute to a better understanding of how spontaneous synchrony is linked to variation in regional architecture across the lateral cortical surface. PMID:27019319

  3. Neural network model of cortical EEG response to olfactory stimuli

    NASA Astrophysics Data System (ADS)

    Dunbar, George L.; Van Toller, Steve

    1995-04-01

    We describe three experiments attempting to model differences in cortical EEG following stimulation with different odors. The data used in these experiments was obtained in previous studies, described briefly here. Subjects sit in an environmentally stabilized low odor cubicle. Twenty-eight electrodes are placed on the scalp and connect the subject to a neurosciences brain imager, which digitizes cortical EEG response. In a given trial, a specific odor is introduced, and the response recorded. In the first experiment, alpha wave data from a subset of ten electrodes and a single subject was used. In the original experiment, the subject was presented with a number of odors and the resulting brain electrical activity was resolved into 16 time slices (5 preceding presentation, 4 during presentation and 7 following presentation). Only data from frames 6, 7 and 8 (during presentation) was used here. A model was constructed to discriminate morning from afternoon responses. The network used measurements from 10 electrodes as input, and backpropagation was used for training. During training, the network was presented with responses to just one odor. Generalization was demonstrated for five other odors. The weights in the network have been analyzed and indicate a role for a specific group of electrode sites in this discrimination. The second experiment involved constructing a network to discriminate cortical EEG responses to two odors. In the original experiment from which we drew our data, fourteen subjects were presented with each odor once. Data from only the frame at first presentation of the odor were used here. Data from three subjects (chosen pseudo-randomly) was selected for use in the generalization phase and dropped from the training set. Output targets were constructed that took account of subjective ratings of `pleasantness.' A feed-forward network with twenty-eight input units was trained using data from the eleven remaining subjects, using conjugate gradient

  4. Diverse cortical codes for scene segmentation in primate auditory cortex

    PubMed Central

    Semple, Malcolm N.

    2015-01-01

    The temporal coherence of amplitude fluctuations is a critical cue for segmentation of complex auditory scenes. The auditory system must accurately demarcate the onsets and offsets of acoustic signals. We explored how and how well the timing of onsets and offsets of gated tones are encoded by auditory cortical neurons in awake rhesus macaques. Temporal features of this representation were isolated by presenting otherwise identical pure tones of differing durations. Cortical response patterns were diverse, including selective encoding of onset and offset transients, tonic firing, and sustained suppression. Spike train classification methods revealed that many neurons robustly encoded tone duration despite substantial diversity in the encoding process. Excellent discrimination performance was achieved by neurons whose responses were primarily phasic at tone offset and by those that responded robustly while the tone persisted. Although diverse cortical response patterns converged on effective duration discrimination, this diversity significantly constrained the utility of decoding models referenced to a spiking pattern averaged across all responses or averaged within the same response category. Using maximum likelihood-based decoding models, we demonstrated that the spike train recorded in a single trial could support direct estimation of stimulus onset and offset. Comparisons between different decoding models established the substantial contribution of bursts of activity at sound onset and offset to demarcating the temporal boundaries of gated tones. Our results indicate that relatively few neurons suffice to provide temporally precise estimates of such auditory “edges,” particularly for models that assume and exploit the heterogeneity of neural responses in awake cortex. PMID:25695655

  5. Simulating Cortical Feedback Modulation as Changes in Excitation and Inhibition in a Cortical Circuit Model

    PubMed Central

    Murray, John D.; McCormick, David A.

    2016-01-01

    Abstract Cortical feedback pathways are hypothesized to distribute context-dependent signals during flexible behavior. Recent experimental work has attempted to understand the mechanisms by which cortical feedback inputs modulate their target regions. Within the mouse whisker sensorimotor system, cortical feedback stimulation modulates spontaneous activity and sensory responsiveness, leading to enhanced sensory representations. However, the cellular mechanisms underlying these effects are currently unknown. In this study we use a simplified neural circuit model, which includes two recurrent excitatory populations and global inhibition, to simulate cortical modulation. First, we demonstrate how changes in the strengths of excitation and inhibition alter the input–output processing responses of our model. Second, we compare these responses with experimental findings from cortical feedback stimulation. Our analyses predict that enhanced inhibition underlies the changes in spontaneous and sensory evoked activity observed experimentally. More generally, these analyses provide a framework for relating cellular and synaptic properties to emergent circuit function and dynamic modulation. PMID:27595137

  6. Simulating Cortical Feedback Modulation as Changes in Excitation and Inhibition in a Cortical Circuit Model.

    PubMed

    Zagha, Edward; Murray, John D; McCormick, David A

    2016-01-01

    Cortical feedback pathways are hypothesized to distribute context-dependent signals during flexible behavior. Recent experimental work has attempted to understand the mechanisms by which cortical feedback inputs modulate their target regions. Within the mouse whisker sensorimotor system, cortical feedback stimulation modulates spontaneous activity and sensory responsiveness, leading to enhanced sensory representations. However, the cellular mechanisms underlying these effects are currently unknown. In this study we use a simplified neural circuit model, which includes two recurrent excitatory populations and global inhibition, to simulate cortical modulation. First, we demonstrate how changes in the strengths of excitation and inhibition alter the input-output processing responses of our model. Second, we compare these responses with experimental findings from cortical feedback stimulation. Our analyses predict that enhanced inhibition underlies the changes in spontaneous and sensory evoked activity observed experimentally. More generally, these analyses provide a framework for relating cellular and synaptic properties to emergent circuit function and dynamic modulation. PMID:27595137

  7. Symmetry breaking in reconstituted actin cortices.

    PubMed

    Abu Shah, Enas; Keren, Kinneret

    2014-01-01

    The actin cortex plays a pivotal role in cell division, in generating and maintaining cell polarity and in motility. In all these contexts, the cortical network has to break symmetry to generate polar cytoskeletal dynamics. Despite extensive research, the mechanisms responsible for regulating cortical dynamics in vivo and inducing symmetry breaking are still unclear. Here we introduce a reconstituted system that self-organizes into dynamic actin cortices at the inner interface of water-in-oil emulsions. This artificial system undergoes spontaneous symmetry breaking, driven by myosin-induced cortical actin flows, which appears remarkably similar to the initial polarization of the embryo in many species. Our in vitro model system recapitulates the rich dynamics of actin cortices in vivo, revealing the basic biophysical and biochemical requirements for cortex formation and symmetry breaking. Moreover, this synthetic system paves the way for further exploration of artificial cells towards the realization of minimal model systems that can move and divide.DOI: http://dx.doi.org/10.7554/eLife.01433.001. PMID:24843007

  8. Automatic parcellation of longitudinal cortical surfaces

    NASA Astrophysics Data System (ADS)

    Alassaf, Manal H.; Hahn, James K.

    2015-03-01

    We present a novel automatic method to parcellate the cortical surfaces of the neonatal brain longitudinal atlas at different stages of development. A labeled brain atlas of newborn at 41 weeks gestational age (GA) is used to propagate labels of anatomical regions of interest to an unlabeled spatio-temporal atlas, which provides a dynamic model of brain development at each week between 28-44 GA weeks. First, labels from the cortical volume of the labeled newborn brain are propagated to an age-matched cortical surface from the spatio-temporal atlas. Then, labels are propagated across the cortical surfaces of each week of the spatio-temporal atlas by registering successive cortical surfaces using a novel approach and an energy optimization function. This procedure incorporates local and global, spatial and temporal information when assigning the labels to each surface. The result is a complete parcellation of 17 neonatal brain surfaces of the spatio-temporal atlas with similar points per labels distributions across weeks.

  9. Human Cortical Excitability Increases with Time Awake

    PubMed Central

    Huber, Reto; Mäki, Hanna; Rosanova, Mario; Casarotto, Silvia; Canali, Paola; Casali, Adenauer G.; Tononi, Giulio

    2013-01-01

    Prolonged wakefulness is associated not only with obvious changes in the way we feel and perform but also with well-known clinical effects, such as increased susceptibility to seizures, to hallucinations, and relief of depressive symptoms. These clinical effects suggest that prolonged wakefulness may be associated with significant changes in the state of cortical circuits. While recent animal experiments have reported a progressive increase of cortical excitability with time awake, no conclusive evidence could be gathered in humans. In this study, we combine transcranial magnetic stimulation (TMS) and electroencephalography (EEG) to monitor cortical excitability in healthy individuals as a function of time awake. We observed that the excitability of the human frontal cortex, measured as the immediate (0–20 ms) EEG reaction to TMS, progressively increases with time awake, from morning to evening and after one night of total sleep deprivation, and that it decreases after recovery sleep. By continuously monitoring vigilance, we also found that this modulation in cortical responsiveness is tonic and not attributable to transient fluctuations of the level of arousal. The present results provide noninvasive electrophysiological evidence that wakefulness is associated with a steady increase in the excitability of human cortical circuits that is rebalanced during sleep. PMID:22314045

  10. Accelerated longitudinal cortical thinning in adolescence.

    PubMed

    Zhou, Dongming; Lebel, Catherine; Treit, Sarah; Evans, Alan; Beaulieu, Christian

    2015-01-01

    It remains unclear if changes of the cerebral cortex occur gradually from childhood to adulthood, or if adolescence marks a differential period of cortical development. In the current study of 90 healthy volunteers aged 5-32years (48 females, 85 right handed) with 180 scans (2 scans for each participant with ~4year gaps), thinning of overall mean thickness and across the four major cortical lobes bilaterally was observed across this full age span. However, the thinning rate, calculated as Δcortical thickness/Δage (mm/year) between scans of each participant, revealed an accelerated cortical thinning during adolescence, which was preceded by less thinning in childhood and followed by decelerated thinning in young adulthood. Males and females showed similarly faster thinning rates during adolescence relative to young adults. The underlying basis and role of accelerated cortical thinning during adolescence for cognition, behaviour and disorders that appear at such a stage of development remains to be determined in future work. PMID:25312772

  11. Symmetry breaking in reconstituted actin cortices

    PubMed Central

    Abu Shah, Enas; Keren, Kinneret

    2014-01-01

    The actin cortex plays a pivotal role in cell division, in generating and maintaining cell polarity and in motility. In all these contexts, the cortical network has to break symmetry to generate polar cytoskeletal dynamics. Despite extensive research, the mechanisms responsible for regulating cortical dynamics in vivo and inducing symmetry breaking are still unclear. Here we introduce a reconstituted system that self-organizes into dynamic actin cortices at the inner interface of water-in-oil emulsions. This artificial system undergoes spontaneous symmetry breaking, driven by myosin-induced cortical actin flows, which appears remarkably similar to the initial polarization of the embryo in many species. Our in vitro model system recapitulates the rich dynamics of actin cortices in vivo, revealing the basic biophysical and biochemical requirements for cortex formation and symmetry breaking. Moreover, this synthetic system paves the way for further exploration of artificial cells towards the realization of minimal model systems that can move and divide. DOI: http://dx.doi.org/10.7554/eLife.01433.001 PMID:24843007

  12. Malformations of cortical development and epilepsy.

    PubMed

    Leventer, Richard J; Guerrini, Renzo; Dobyns, William B

    2008-01-01

    Malformations of cortical development (MCDs) are macroscopic or microscopic abnormalities of the cerebral cortex that arise as a consequence of an interruption to the normal steps of formation of the cortical plate. The human cortex develops its basic structure during the first two trimesters of pregnancy as a series of overlapping steps, beginning with proliferation and differentiation of neurons, which then migrate before finally organizing themselves in the developing cortex. Abnormalities at any of these stages, be they environmental or genetic in origin, may cause disruption of neuronal circuitry and predispose to a variety of clinical consequences, the most common of which is epileptic seizures. A large number of MCDs have now been described, each with characteristic pathological, clinical, and imaging features. The causes of many of these MCDs have been determined through the study of affected individuals, with many MCDs now established as being secondary to mutations in cortical development genes. This review will highlight the best-known of the human cortical malformations associated with epilepsy. The pathological, clinical, imaging, and etiologic features of each MCD will be summarized, with representative magnetic resonance imaging (MRI) images shown for each MCD. The malformations tuberous sclerosis, focal cortical dysplasia, hemimegalencephaly, classical lissencephaly, subcortical band heterotopia, periventricular nodular heterotopia, polymicrogyria, and schizencephaly will be presented. PMID:18472484

  13. Evaluating interhemispheric cortical responses to transcranial magnetic stimulation in chronic stroke: A TMS-EEG investigation.

    PubMed

    Borich, Michael R; Wheaton, Lewis A; Brodie, Sonia M; Lakhani, Bimal; Boyd, Lara A

    2016-04-01

    TMS-evoked cortical responses can be measured using simultaneous electroencephalography (TMS-EEG) to directly quantify cortical connectivity in the human brain. The purpose of this study was to evaluate interhemispheric cortical connectivity between the primary motor cortices (M1s) in participants with chronic stroke and controls using TMS-EEG. Ten participants with chronic stroke and four controls were tested. TMS-evoked responses were recorded at rest and during a typical TMS assessment of transcallosal inhibition (TCI). EEG recordings from peri-central gyral electrodes (C3 and C4) were evaluated using imaginary phase coherence (IPC) analyses to quantify levels of effective interhemispheric connectivity. Significantly increased TMS-evoked beta (15-30Hz frequency range) IPC was observed in the stroke group during ipsilesional M1 stimulation compared to controls during TCI assessment but not at rest. TMS-evoked beta IPC values were associated with TMS measures of transcallosal inhibition across groups. These results suggest TMS-evoked EEG responses can index abnormal effective interhemispheric connectivity in chronic stroke. PMID:26940237

  14. Axono-cortical evoked potentials: A proof-of-concept study.

    PubMed

    Mandonnet, E; Dadoun, Y; Poisson, I; Madadaki, C; Froelich, S; Lozeron, P

    2016-04-01

    Awake surgery is currently considered the best method to tailor intraparenchymatous resections according to functional boundaries. However, the exact mechanisms by which electrical stimulation disturbs behavior remain largely unknown. In this case report, we describe a new method to explore the propagation toward cortical sites of a brief pulse applied to an eloquent white matter pathway. We present a patient, operated on in awake condition for removal of a cavernoma of the left ventral premotor cortex. At the end of the resection, the application of 60Hz stimulation in the white matter of the operculum induced anomia. Stimulating the same site at a frequency of 1Hz during 70seconds allowed to record responses on electrodes put over Broca's area and around the inferior part of central sulcus. Axono-cortical evoked potentials were then obtained by averaging unitary responses, time-locked to the stimulus. We then discuss the origin of these evoked axono-cortical potentials and the likely pathway connecting the stimulation site to the recorded cortical sites. PMID:26688046

  15. Differential representation of arm movement direction in relation to cortical anatomy and function

    NASA Astrophysics Data System (ADS)

    Ball, Tonio; Schulze-Bonhage, Andreas; Aertsen, Ad; Mehring, Carsten

    2009-02-01

    Information about arm movement direction in neuronal activity of the cerebral cortex can be used for movement control mediated by a brain-machine interface (BMI). Here we provide a topographic analysis of the information related to arm movement direction that can be extracted from single trials of electrocorticographic (ECoG) signals recorded from the human frontal and parietal cortex based on a precise assignment of ECoG recording channels to the subjects' individual cortical anatomy and function. To this aim, each electrode contact was identified on structural MRI scans acquired while the electrodes were implanted and was thus related to the brain anatomy of each patient. Cortical function was assessed by direct cortical electrical stimulation. We show that activity from the primary motor cortex, in particular from the region showing hand and arm motor responses upon electrical stimulation, carries most directional information. The premotor, posterior parietal and lateral prefrontal cortex contributed gradually less, but still significant information. This gradient was observed for decoding from movement-related potentials, and from spectral amplitude modulations in low frequencies and in the high gamma band. Our findings thus demonstrate a close topographic correlation between cortical functional anatomy and direction-related information in humans that might be used for brain-machine interfacing.

  16. Fearful faces heighten the cortical representation of contextual threat

    PubMed Central

    Wieser, Matthias J.; Keil, Andreas

    2015-01-01

    Perception of facial expressions is typically investigated by presenting isolated face stimuli. In everyday life, however, faces are rarely seen without a surrounding visual context that affects perception and interpretation of the facial expression. Conversely, fearful faces may act as a cue, heightening the sensitivity of the visual system to effectively detect potential threat in the environment. In the present study, we used steady-state visually evoked potentials (ssVEPs) to examine the mutual effects of facial expressions (fearful, neutral, happy) and affective visual context (pleasant, neutral, threat). By assigning two different flicker frequencies (12 vs. 15 Hz) to the face and the visual context scene, cortical activity to the concurrent stimuli was separated, which represents a novel approach to independently tracking the cortical processes associated with the face and the context. Twenty healthy students viewed flickering faces overlaid on flickering visual scenes, while performing a simple change-detection task at fixation, and high-density EEG was recorded. Arousing background scenes generally drove larger ssVEP amplitudes than neutral scenes. Importantly, background and expression interacted: When viewing fearful facial expressions, the ssVEP in response to threat context was amplified compared to other backgrounds. Together, these findings suggest that fearful faces elicit vigilance for potential threat in the visual periphery. PMID:24125792

  17. Mitochondrial activity and brain functions during cortical depolarization

    NASA Astrophysics Data System (ADS)

    Mayevsky, Avraham; Sonn, Judith

    2008-12-01

    Cortical depolarization (CD) of the cerebral cortex could be developed under various pathophysiological conditions. In animal models, CD was recorded under partial or complete ischemia as well as when cortical spreading depression (SD) was induced externally or by internal stimulus. The development of CD in patients and the changes in various metabolic parameters, during CD, was rarely reported. Brain metabolic, hemodynamic, ionic and electrical responses to the CD event are dependent upon the O2 balance in the tissue. When the O2 balance is negative (i.e. ischemia), the CD process will be developed due to mitochondrial dysfunction, lack of energy and the inhibition of Na+-K+-ATPase. In contradiction, when oxygen is available (i.e. normoxia) the development of CD after induction of SD will accelerate mitochondrial respiration for retaining ionic homeostasis and normal brain functions. We used the multiparametric monitoring approach that enable real time monitoring of mitochondrial NADH redox state, microcirculatory blood flow and oxygenation, extracellular K+, Ca2+, H+ levels, DC steady potential and electrocorticogram (ECoG). This monitoring approach, provide a unique tool that has a significant value in analyzing the pathophysiology of the brain when SD developed under normoxia, ischemia, or hypoxia. We applied the same monitoring approach to patients suffered from severe head injury or exposed to neurosurgical procedures.

  18. Functional Cortical Network in Alpha Band Correlates with Social Bargaining

    PubMed Central

    Billeke, Pablo; Zamorano, Francisco; Chavez, Mario; Cosmelli, Diego; Aboitiz, Francisco

    2014-01-01

    Solving demanding tasks requires fast and flexible coordination among different brain areas. Everyday examples of this are the social dilemmas in which goals tend to clash, requiring one to weigh alternative courses of action in limited time. In spite of this fact, there are few studies that directly address the dynamics of flexible brain network integration during social interaction. To study the preceding, we carried out EEG recordings while subjects played a repeated version of the Ultimatum Game in both human (social) and computer (non-social) conditions. We found phase synchrony (inter-site-phase-clustering) modulation in alpha band that was specific to the human condition and independent of power modulation. The strength and patterns of the inter-site-phase-clustering of the cortical networks were also modulated, and these modulations were mainly in frontal and parietal regions. Moreover, changes in the individuals’ alpha network structure correlated with the risk of the offers made only in social conditions. This correlation was independent of changes in power and inter-site-phase-clustering strength. Our results indicate that, when subjects believe they are participating in a social interaction, a specific modulation of functional cortical networks in alpha band takes place, suggesting that phase synchrony of alpha oscillations could serve as a mechanism by which different brain areas flexibly interact in order to adapt ongoing behavior in socially demanding contexts. PMID:25286240

  19. Aging induced cortical drive alterations during sleep in rats.

    PubMed

    Ciric, Jelena; Lazic, Katarina; Petrovic, Jelena; Kalauzi, Aleksandar; Saponjic, Jasna

    2015-03-01

    We followed the impact of healthy aging on cortical drive during sleep in rats by using the corticomuscular coherence (CMC). We employed the chronic electrodes implantation for sleep recording in adult, male Wistar rats, and followed the aging impact during sleep from 3 to 5.5 months age. We have analyzed the sleep/wake states architecture, and the sleep/wake state related EEG microstructure and CMCs. We evidenced the topographically distinct impact of aging on sleep/wake states architecture within the sensorimotor (SMCx) vs. motor cortex (MCx) from 4.5 to 5.5 months age. Healthy aging consistently altered only the SMCx sleep/wake states architecture, and increased the delta and beta CMCs through both cortical drives during Wake, but only through the MCx drive during REM. According to the delta and beta CMCs values, aging impact through the SMCx drive was opposite, but it was convergent through the MCx drive during Wake vs. REM, and there was a dual and inverse mode for the motor control during REM. PMID:25773067

  20. SLEEP/WAKE DEPENDENT CHANGES IN CORTICAL GLUCOSE CONCENTRATIONS

    PubMed Central

    Dash, Michael B; Bellesi, Michele; Tononi, Giulio; Cirelli, Chiara

    2012-01-01

    Most of the energy in the brain comes from glucose and supports glutamatergic activity. The firing rate of cortical glutamatergic neurons, as well as cortical extracellular glutamate levels, increase with time spent awake and decline throughout non rapid eye movement (NREM) sleep, raising the question whether glucose levels reflect behavioral state and sleep/wake history. Here chronic (2–3 days) electroencephalographic (EEG) recordings in the rat cerebral cortex were coupled with fixed-potential amperometry to monitor the extracellular concentration of glucose ([gluc]) on a second-by-second basis across the spontaneous sleep-wake cycle and in response to 3 hours of sleep deprivation. [Gluc] progressively increased during NREM sleep and declined during REM sleep, while during wake an early decline in [gluc] was followed by an increase 8–15 minutes after awakening. There was a significant time of day effect during the dark phase, when rats are mostly awake, with [gluc] being significantly lower during the last 3–4 hours of the night relative to the first 3–4 hours. Moreover, the duration of the early phase of [gluc] decline during wake was longer after prolonged wake than after consolidated sleep. Thus, the sleep/wake history may affect the levels of glucose available to the brain upon awakening. PMID:23106535

  1. The organization of two novel cortical interneuronal circuits

    PubMed Central

    Jiang, Xiaolong; Wang, Guangfu; Lee, Alice J.; Stornetta, Ruth L.; Zhu, J. Julius

    2013-01-01

    Deciphering interneuronal circuitry is central to understanding brain functions yet remains as a challenging task in neurobiology. Using simultaneous quadruple-octuple in vitro and dual in vivo whole-cell recordings, we found two previously unknown interneuronal circuits that link cortical layer 1–3 (L1-3) interneurons and L5 pyramidal neurons in the rat neocortex. L1 single-bouquet cells (SBCs) preferentially form unidirectional inhibitory connections on L2/3 interneurons that inhibit the entire dendritic-somato-axonal axis of ~1% of L5 pyramidal neurons located within the same column. In contrast, L1 elongated neurogliaform cells (ENGCs) frequently form mutual inhibitory and electric connections with L2/3 interneurons, and these L1-3 interneurons inhibit the distal apical dendrite of >60% of L5 pyramidal neurons across multiple columns. Functionally, SBC→L2/3 interneuron→L5 pyramidal neuronal circuits disinhibit and ENGC↔L2/3 interneuron→L5 pyramidal neuronal circuits inhibit the initiation of dendritic complex spikes in L5 pyramidal neurons. As dendritic complex spikes can serve coincidence detection, these cortical interneuronal circuits may be essential for salience selection. PMID:23313910

  2. Late cortical disinhibition in relaxed versus active hand muscles.

    PubMed

    Caux-Dedeystère, A; Derambure, P; Devanne, H

    2015-07-01

    Recent research suggests that long-interval intracortical inhibition (LICI) is followed by a transitory period of late cortical disinhibition (LCD) that can even lead to a net increase in cortical excitability. The relationship between LICI/LCD and voluntary drive remains poorly understood. Our study aims at investigating the influence of index abduction on LICI and LCD in an actively engaged muscle and a neighboring muscle, while varying the intensity of the conditioning stimulus (CS). Motor-evoked potentials (MEPs) were recorded from the first dorsal interosseus (FDI) and abductor digiti minimi (ADM) muscles in 13 subjects. Paired-pulses were delivered with 10 different interstimulus intervals (ranging from 60 to 290 ms). Whatever the condition (relaxed or active FDI), the test stimulus was set to evoke an MEP of 1mV. The time course of conditioned MEP amplitude was compared for relaxed and active conditions when the CS intensity was set to (i) 130% of the rest motor threshold (RMT) or (ii) to evoke the same size of MEP under both conditions. LICI lasted longer (i.e. disinhibition occurred later) at rest than during abduction when evoked either by similar or matched conditioning stimuli. No post-LICI facilitation was observed at rest - even when the CS intensity was set to 160% RMT. In contrast, long-interval intracortical facilitation (LICF) was observed in the quiescent ADM when FDI was active. LICF may then be associated with voluntary activity albeit with lack of topographic specificity. PMID:25888934

  3. Prefrontal cortical microcircuits bind perception to executive control

    NASA Astrophysics Data System (ADS)

    Opris, Ioan; Santos, Lucas; Gerhardt, Greg A.; Song, Dong; Berger, Theodore W.; Hampson, Robert E.; Deadwyler, Sam A.

    2013-07-01

    During the perception-to-action cycle, our cerebral cortex mediates the interactions between the environment and the perceptual-executive systems of the brain. At the top of the executive hierarchy, prefrontal cortical microcircuits are assumed to bind perceptual and executive control information to guide goal-driven behavior. Here, we tested this hypothesis by comparing simultaneously recorded neuron firing in prefrontal cortical layers and the caudate-putamen of rhesus monkeys, trained in a spatial-versus-object, rule-based match-to-sample task. We found that during the perception and executive selection phases, cell firing in the localized prefrontal layers and caudate-putamen region exhibited similar location preferences on spatial-trials, but less on object- trials. Then, we facilitated the perceptual-executive circuit by stimulating the prefrontal infra-granular-layers with patterns previously derived from supra-granular-layers, and produced stimulation-induced spatial preference in percent correct performance on spatial trials, similar to neural tuning. These results show that inter-laminar prefrontal microcircuits play causal roles to the perception-to-action cycle.

  4. Effect of electrode cap on measured cortical motor threshold.

    PubMed

    Julkunen, Petro; Säisänen, Laura; Sarasti, Maria; Könönen, Mervi

    2009-01-30

    We investigated the role of electrode cap use in the determination of the cortical motor threshold (MT), and the resulting changes in the recorded motor evoked potentials (MEPs). We also tested whether the induced changes in determined MT could be corrected via previously introduced correction method. Sixteen healthy subjects were studied. Navigated TMS was used for mapping the optimal representation area of the thenar musculature in the primary motor cortex and individual MTs were determined with and without the use of the electrode cap. A mathematical correction was utilized to compensate for the effect of electrode cap in the MTs. Individual MEPs were also measured. We observed a significant (p<0.05) increase in the determined MTs attributable to the use of the electrode cap. At the group level this difference was reduced significantly (p<0.01) by the use of the correction method. However, at the individual level the efficiency of the correction was poor. The MEP-amplitudes were not affected whether measured with or without the electrode cap. The electrode cap affects significantly the cortical MT measured as stimulation intensity making the comparison of MTs difficult with other studies not having used an electrode cap. PMID:18801386

  5. Highly Nonrandom Features of Synaptic Connectivity in Local Cortical Circuits

    PubMed Central

    2005-01-01

    How different is local cortical circuitry from a random network? To answer this question, we probed synaptic connections with several hundred simultaneous quadruple whole-cell recordings from layer 5 pyramidal neurons in the rat visual cortex. Analysis of this dataset revealed several nonrandom features in synaptic connectivity. We confirmed previous reports that bidirectional connections are more common than expected in a random network. We found that several highly clustered three-neuron connectivity patterns are overrepresented, suggesting that connections tend to cluster together. We also analyzed synaptic connection strength as defined by the peak excitatory postsynaptic potential amplitude. We found that the distribution of synaptic connection strength differs significantly from the Poisson distribution and can be fitted by a lognormal distribution. Such a distribution has a heavier tail and implies that synaptic weight is concentrated among few synaptic connections. In addition, the strengths of synaptic connections sharing pre- or postsynaptic neurons are correlated, implying that strong connections are even more clustered than the weak ones. Therefore, the local cortical network structure can be viewed as a skeleton of stronger connections in a sea of weaker ones. Such a skeleton is likely to play an important role in network dynamics and should be investigated further. PMID:15737062

  6. Focal cortical dysplasias in autism spectrum disorders

    PubMed Central

    2013-01-01

    Background Previous reports indicate the presence of histological abnormalities in the brains of individuals with autism spectrum disorders (ASD) suggestive of a dysplastic process. In this study we identified areas of abnormal cortical thinning within the cerebral cortex of ASD individuals and examined the same for neuronal morphometric abnormalities by using computerized image analysis. Results The study analyzed celloidin-embedded and Nissl-stained serial full coronal brain sections of 7 autistic (ADI-R diagnosed) and 7 age/sex-matched neurotypicals. Sections were scanned and manually segmented before implementing an algorithm using Laplace’s equation to measure cortical width. Identified areas were then subjected to analysis for neuronal morphometry. Results of our study indicate the presence within our ASD population of circumscribed foci of diminished cortical width that varied among affected individuals both in terms of location and overall size with the frontal lobes being particularly involved. Spatial statistic indicated a reduction in size of neurons within affected areas. Granulometry confirmed the presence of smaller pyramidal cells and suggested a concomitant reduction in the total number of interneurons. Conclusions The neuropathology is consistent with a diagnosis of focal cortical dysplasia (FCD). Results from the medical literature (e.g., heterotopias) and our own study suggest that the genesis of this cortical malformation seemingly resides in the heterochronic divisions of periventricular germinal cells. The end result is that during corticogenesis radially migrating neuroblasts (future pyramidal cells) are desynchronized in their development from those that follow a tangential route (interneurons). The possible presence of a pathological mechanism in common among different conditions expressing an autism-like phenotype argue in favor of considering ASD a “sequence” rather than a syndrome. Focal cortical dysplasias in ASD may serve to

  7. Sparse cortical source localization using spatio-temporal atoms.

    PubMed

    Korats, Gundars; Ranta, Radu; Le Cam, Steven; Louis-Dorr, Valérie

    2015-08-01

    This paper addresses the problem of sparse localization of cortical sources from scalp EEG recordings. Localization algorithms use propagation model under spatial and/or temporal constraints, but their performance highly depends on the data signal-to-noise ratio (SNR). In this work we propose a dictionary based sparse localization method which uses a data driven spatio-temporal dictionary to reconstruct the measurements using Single Best Replacement (SBR) and Continuation Single Best Replacement (CSBR) algorithms. We tested and compared our methods with the well-known MUSIC and RAP-MUSIC algorithms on simulated realistic data. Tests were carried out for different noise levels. The results show that our method has a strong advantage over MUSIC-type methods in case of synchronized sources. PMID:26737185

  8. Facilitated early cortical processing of nude human bodies.

    PubMed

    Alho, Jussi; Salminen, Nelli; Sams, Mikko; Hietanen, Jari K; Nummenmaa, Lauri

    2015-07-01

    Functional brain imaging has identified specialized neural systems supporting human body perception. Responses to nude vs. clothed bodies within this system are amplified. However, it remains unresolved whether nude and clothed bodies are processed by same cerebral networks or whether processing of nude bodies recruits additional affective and arousal processing areas. We recorded simultaneous MEG and EEG while participants viewed photographs of clothed and nude bodies. Global field power revealed a peak ∼145ms after stimulus onset to both clothed and nude bodies, and ∼205ms exclusively to nude bodies. Nude-body-sensitive responses were centered first (100-200ms) in the extrastriate and fusiform body areas, and subsequently (200-300ms) in affective-motivational areas including insula and anterior cingulate cortex. We conclude that visibility of sexual features facilitates early cortical processing of human bodies, the purpose of which is presumably to trigger sexual behavior and ultimately ensure reproduction. PMID:25960070

  9. Cortical Reorganisation during a 30-Week Tinnitus Treatment Program.

    PubMed

    McMahon, Catherine M; Ibrahim, Ronny K; Mathur, Ankit

    2016-01-01

    Subjective tinnitus is characterised by the conscious perception of a phantom sound. Previous studies have shown that individuals with chronic tinnitus have disrupted sound-evoked cortical tonotopic maps, time-shifted evoked auditory responses, and altered oscillatory cortical activity. The main objectives of this study were to: (i) compare sound-evoked brain responses and cortical tonotopic maps in individuals with bilateral tinnitus and those without tinnitus; and (ii) investigate whether changes in these sound-evoked responses occur with amelioration of the tinnitus percept during a 30-week tinnitus treatment program. Magnetoencephalography (MEG) recordings of 12 bilateral tinnitus participants and 10 control normal-hearing subjects reporting no tinnitus were recorded at baseline, using 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz tones presented monaurally at 70 dBSPL through insert tube phones. For the tinnitus participants, MEG recordings were obtained at 5-, 10-, 20- and 30- week time points during tinnitus treatment. Results for the 500 Hz and 1000 Hz sources (where hearing thresholds were within normal limits for all participants) showed that the tinnitus participants had a significantly larger and more anteriorly located source strengths when compared to the non-tinnitus participants. During the 30-week tinnitus treatment, the participants' 500 Hz and 1000 Hz source strengths remained higher than the non-tinnitus participants; however, the source locations shifted towards the direction recorded from the non-tinnitus control group. Further, in the left hemisphere, there was a time-shifted association between the trajectory of change of the individual's objective (source strength and anterior-posterior source location) and subjective measures (using tinnitus reaction questionnaire, TRQ). The differences in source strength between the two groups suggest that individuals with tinnitus have enhanced central gain which is not significantly influenced by the tinnitus

  10. Modeling cortical source dynamics and interactions during seizure.

    PubMed

    Mullen, Tim; Acar, Zeynep Akalin; Worrell, Gregory; Makeig, Scott

    2011-01-01

    Mapping the dynamics and spatial topography of brain source processes critically involved in initiating and propagating seizure activity is critical for effective epilepsy diagnosis, intervention, and treatment. In this report we analyze neuronal dynamics before and during epileptic seizures using adaptive multivariate autoregressive (VAR) models applied to maximally-independent (ICA) sources of intracranial EEG (iEEG, ECoG) data recorded from subdural electrodes implanted in a human patient for evaluation of surgery for epilepsy. We visualize the spatial distribution of causal sources and sinks of ictal activity on the cortical surface (gyral and sulcal) using a novel combination of multivariate Granger-causal and graph-theoretic metrics combined with distributed source localization by Sparse Bayesian Learning applied to a multi-scale patch basis. This analysis reveals and visualizes distinct, seizure stage-dependent shifts in inter-component spatiotemporal dynamics and connectivity including the clinically-identified epileptic foci. PMID:22254582

  11. Cortical Reorganisation during a 30-Week Tinnitus Treatment Program

    PubMed Central

    McMahon, Catherine M.; Ibrahim, Ronny K.; Mathur, Ankit

    2016-01-01

    Subjective tinnitus is characterised by the conscious perception of a phantom sound. Previous studies have shown that individuals with chronic tinnitus have disrupted sound-evoked cortical tonotopic maps, time-shifted evoked auditory responses, and altered oscillatory cortical activity. The main objectives of this study were to: (i) compare sound-evoked brain responses and cortical tonotopic maps in individuals with bilateral tinnitus and those without tinnitus; and (ii) investigate whether changes in these sound-evoked responses occur with amelioration of the tinnitus percept during a 30-week tinnitus treatment program. Magnetoencephalography (MEG) recordings of 12 bilateral tinnitus participants and 10 control normal-hearing subjects reporting no tinnitus were recorded at baseline, using 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz tones presented monaurally at 70 dBSPL through insert tube phones. For the tinnitus participants, MEG recordings were obtained at 5-, 10-, 20- and 30- week time points during tinnitus treatment. Results for the 500 Hz and 1000 Hz sources (where hearing thresholds were within normal limits for all participants) showed that the tinnitus participants had a significantly larger and more anteriorly located source strengths when compared to the non-tinnitus participants. During the 30-week tinnitus treatment, the participants’ 500 Hz and 1000 Hz source strengths remained higher than the non-tinnitus participants; however, the source locations shifted towards the direction recorded from the non-tinnitus control group. Further, in the left hemisphere, there was a time-shifted association between the trajectory of change of the individual’s objective (source strength and anterior-posterior source location) and subjective measures (using tinnitus reaction questionnaire, TRQ). The differences in source strength between the two groups suggest that individuals with tinnitus have enhanced central gain which is not significantly influenced by the

  12. Mapping gray matter volume and cortical thickness in Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    Guo, Xiaojuan; Li, Ziyi; Chen, Kewei; Yao, Li; Wang, Zhiqun; Li, Kuncheng

    2010-03-01

    Gray matter volume and cortical thickness are two important indices widely used to detect neuropathological changes in brain structural magnetic resonance imaging. Using optimized voxel-based morphometry (VBM) protocol and surface-based cortical thickness measure, this study comprehensively investigated the regional changes in cortical gray matter volume and cortical thickness in Alzheimer's disease (AD). Thirteen patients with AD and fourteen age- and gender-matched healthy controls were included in this study. Results showed that voxel-based gray matter volume and cortical thickness reductions were highly correlated in the temporal lobe and its medial structure in AD. Moreover significant reduced cortical regions of gray matter volume were obviously more than that of cortical thickness. These findings suggest that gray matter volume and cortical thickness, as two important imaging markers, are effective indices for detecting the neuroanatomical alterations and help us understand the neuropathology from different views in AD.

  13. Cortical Hemisphere Registration Via Large Deformation Diffeomorphic Metric Curve Mapping

    PubMed Central

    Qiu, Anqi; Miller, Michael I.

    2010-01-01

    We present large deformation diffeomorphic metric curve mapping (LDDMM-Curve) for registering cortical hemispheres. We showed global cortical hemisphere matching and evaluated the mapping accuracy in five subregions of the cortex in fourteen MRI scans. PMID:18051058

  14. Human Temporal Cortical Single Neuron Activity during Language: A Review

    PubMed Central

    Ojemann, George A.

    2013-01-01

    Findings from recordings of human temporal cortical single neuron activity during several measures of language, including object naming and word reading are reviewed and related to changes in activity in the same neurons during recent verbal memory and verbal associative learning measures, in studies conducted during awake neurosurgery for the treatment of epilepsy. The proportion of neurons changing activity with language tasks was similar in either hemisphere. Dominant hemisphere activity was characterized by relative inhibition, some of which occurred during overt speech, possibly to block perception of one’s own voice. However, the majority seems to represent a dynamic network becoming active with verbal memory encoding and especially verbal learning, but inhibited during performance of overlearned language tasks. Individual neurons are involved in different networks for different aspects of language, including naming or reading and naming in different languages. The majority of the changes in activity were tonic sustained shifts in firing. Patterned phasic activity for specific language items was very infrequently recorded. Human single neuron recordings provide a unique perspective on the biologic substrate for language, for these findings are in contrast to many of the findings from other techniques for investigating this. PMID:24961418

  15. Magnetic Recording.

    ERIC Educational Resources Information Center

    Lowman, Charles E.

    A guide to the technology of magnetic recorders used in such fields as audio recording, broadcast and closed-circuit television, instrumentation recording, and computer data systems is presented. Included are discussions of applications, advantages, and limitations of magnetic recording, its basic principles and theory of operation, and its…

  16. Microelectrode mapping of tonotopic, laminar, and field-specific organization of thalamo-cortical pathway in rat.

    PubMed

    Shiramatsu, Tomoyo Isoguchi; Takahashi, Kazusa; Noda, Takahiro; Kanzaki, Ryohei; Nakahara, Haruka; Takahashi, Hirokazu

    2016-09-22

    The rat has long been considered an important model system for studying neural mechanisms of auditory perception and learning, and particularly mechanisms involving auditory thalamo-cortical processing. However, the functional topography of the auditory thalamus, or medial geniculate body (MGB) has not yet been fully characterized in the rat, and the anatomically-defined features of field-specific, layer-specific and tonotopic thalamo-cortical projections have never been confirmed electrophysiologically. In the present study, we have established a novel technique for recording simultaneously from a surface microelectrode array on the auditory cortex, and a depth electrode array across auditory cortical layers and within the MGB, and characterized the rat MGB and thalamo-cortical projections under isoflurane anesthesia. We revealed that the ventral division of the MGB (MGv) exhibited a low-high-low CF gradient and long-short-long latency gradient along the dorsolateral-to-ventromedial axis, suggesting that the rat MGv is divided into two subdivisions. We also demonstrated that microstimulation in the MGv elicited cortical activation in layer-specific, region-specific and tonotopically organized manners. To our knowledge, the present study has provided the first and most compelling electrophysiological confirmation of the anatomical organization of the primary thalamo-cortical pathway in the rat, setting the groundwork for further investigation. PMID:27329334

  17. Unimodal primary sensory cortices are directly connected by long-range horizontal projections in the rat sensory cortex

    PubMed Central

    Stehberg, Jimmy; Dang, Phat T.; Frostig, Ron D.

    2014-01-01

    Research based on functional imaging and neuronal recordings in the barrel cortex subdivision of primary somatosensory cortex (SI) of the adult rat has revealed novel aspects of structure-function relationships in this cortex. Specifically, it has demonstrated that single whisker stimulation evokes subthreshold neuronal activity that spreads symmetrically within gray matter from the appropriate barrel area, crosses cytoarchitectural borders of SI and reaches deeply into other unimodal primary cortices such as primary auditory (AI) and primary visual (VI). It was further demonstrated that this spread is supported by a spatially matching underlying diffuse network of border-crossing, long-range projections that could also reach deeply into AI and VI. Here we seek to determine whether such a network of border-crossing, long-range projections is unique to barrel cortex or characterizes also other primary, unimodal sensory cortices and therefore could directly connect them. Using anterograde (BDA) and retrograde (CTb) tract-tracing techniques, we demonstrate that such diffuse horizontal networks directly and mutually connect VI, AI and SI. These findings suggest that diffuse, border-crossing axonal projections connecting directly primary cortices are an important organizational motif common to all major primary sensory cortices in the rat. Potential implications of these findings for topics including cortical structure-function relationships, multisensory integration, functional imaging, and cortical parcellation are discussed. PMID:25309339

  18. Functional connectivity and dynamics of cortical-thalamic networks co-cultured in a dual compartment device

    NASA Astrophysics Data System (ADS)

    Kanagasabapathi, Thirukumaran T.; Massobrio, Paolo; Barone, Rocco Andrea; Tedesco, Mariateresa; Martinoia, Sergio; Wadman, Wytse J.; Decré, Michel M. J.

    2012-06-01

    Co-cultures containing dissociated cortical and thalamic cells may provide a unique model for understanding the pathophysiology in the respective neuronal sub-circuitry. In addition, developing an in vitro dissociated co-culture model offers the possibility of studying the system without influence from other neuronal sub-populations. Here we demonstrate a dual compartment system coupled to microelectrode arrays (MEAs) for co-culturing and recording spontaneous activities from neuronal sub-populations. Propagation of electrical activities between cortical and thalamic regions and their interdependence in connectivity is verified by means of a cross-correlation algorithm. We found that burst events originate in the cortical region and drive the entire cortical-thalamic network bursting behavior while mutually weak thalamic connections play a relevant role in sustaining longer burst events in cortical cells. To support these experimental findings, a neuronal network model was developed and used to investigate the interplay between network dynamics and connectivity in the cortical-thalamic system.

  19. Comparative aspects of cerebral cortical development

    PubMed Central

    Molnár, Zoltán; Métin, Christine; Stoykova, Anastassia; Tarabykin, Victor; Price, David J.; Francis, Fiona; Meyer, Gundela; Dehay, Colette; Kennedy, Henry

    2006-01-01

    This review intends to provide examples how comparative and genetic analyses both contribute to our understanding of the rules for cortical development and evolution. Genetic studies helped to understand evolutionary rules of telencephalic organization in vertebrates. The control of the establishment of conserved telencephalic subdivisions and the formation of boundaries between these subdivisions has been examined and revealed the very specific alterations at the striatocortical junction. Comparative studies and genetic analyses both demonstrated the differential origin and migratory pattern of the two basic neuron types of the cerebral cortex. GABAergic interneurons are mostly generated in the subpallium and a common mechanisms govern their migration to the dorsal cortex in both mammals and sauropsids. The pyramidal neurons are generated within the cortical germinal zone and migrate radially. The earliest generated cell layers comprising preplate cells. Reelin positive Cajal-Retzius cells are a general feature of all vertebrates studied so far, however, there is a considerable amplification of the reelin signaling, which might have contributed to the establishment of the basic mammalian pattern of cortical development. Based on numerous recent observations we shall present an argument that specialization of the mitotic compartments might constitute a major drive behind the evolution of the mammalian cortex. Comparative developmental studies revealed distinct features in the early compartments of the developing macaque brain drawing our attention to the limitations of some of the current model systems for understanding human developmental abnormalities of the cortex. Comparative and genetic aspects of cortical development both reveal the workings of evolution. PMID:16519657

  20. Cortical Memory Mechanisms and Language Origins

    ERIC Educational Resources Information Center

    Aboitiz, Francisco; Garcia, Ricardo R.; Bosman, Conrado; Brunetti, Enzo

    2006-01-01

    We have previously proposed that cortical auditory-vocal networks of the monkey brain can be partly homologized with language networks that participate in the phonological loop. In this paper, we suggest that other linguistic phenomena like semantic and syntactic processing also rely on the activation of transient memory networks, which can be…

  1. The Diversity of Cortical Inhibitory Synapses

    PubMed Central

    Kubota, Yoshiyuki; Karube, Fuyuki; Nomura, Masaki; Kawaguchi, Yasuo

    2016-01-01

    The most typical and well known inhibitory action in the cortical microcircuit is a strong inhibition on the target neuron by axo-somatic synapses. However, it has become clear that synaptic inhibition in the cortex is much more diverse and complicated. Firstly, at least ten or more inhibitory non-pyramidal cell subtypes engage in diverse inhibitory functions to produce the elaborate activity characteristic of the different cortical states. Each distinct non-pyramidal cell subtype has its own independent inhibitory function. Secondly, the inhibitory synapses innervate different neuronal domains, such as axons, spines, dendrites and soma, and their inhibitory postsynaptic potential (IPSP) size is not uniform. Thus, cortical inhibition is highly complex, with a wide variety of anatomical and physiological modes. Moreover, the functional significance of the various inhibitory synapse innervation styles and their unique structural dynamic behaviors differ from those of excitatory synapses. In this review, we summarize our current understanding of the inhibitory mechanisms of the cortical microcircuit. PMID:27199670

  2. Junk DNA Used in Cerebral Cortical Evolution.

    PubMed

    Pratt, Thomas; Price, David J

    2016-06-15

    In this issue of Neuron, Rani et al. (2016) address important questions about the mechanisms of cerebral cortical evolution. They describe how a primate-specific long non-coding RNA titrates the levels of a microRNA that regulates an ancient signaling pathway controlling neuronal numbers. PMID:27311076

  3. Cortical correlates of acquired deafness to dissonance.

    PubMed

    Brattico, Elvira; Tervaniemi, Mari; Valimaki, Vesa; Van Zuijen, Titia; Peretz, Isabelle

    2003-11-01

    Patient I.R., who had bilateral lesions in the auditory cortex but intact hearing, did not distinguish dissonant from consonant musical excerpts in behavioral testing. We additionally found that the electrical brain responses did not differentiate musical intervals in terms of their dissonance/consonance, consistent with the idea that this phenomenon depends on the integrity of cortical functions. PMID:14681131

  4. Stroke rehabilitation using noninvasive cortical stimulation: aphasia.

    PubMed

    Mylius, Veit; Zouari, Hela G; Ayache, Samar S; Farhat, Wassim H; Lefaucheur, Jean-Pascal

    2012-08-01

    Poststroke aphasia results from the lesion of cortical areas involved in the motor production of speech (Broca's aphasia) or in the semantic aspects of language comprehension (Wernicke's aphasia). Such lesions produce an important reorganization of speech/language-specific brain networks due to an imbalance between cortical facilitation and inhibition. In fact, functional recovery is associated with changes in the excitability of the damaged neural structures and their connections. Two main mechanisms are involved in poststroke aphasia recovery: the recruitment of perilesional regions of the left hemisphere in case of small lesion and the acquisition of language processing ability in homotopic areas of the nondominant right hemisphere when left hemispheric language abilities are permanently lost. There is some evidence that noninvasive cortical stimulation, especially when combined with language therapy or other therapeutic approaches, can promote aphasia recovery. Cortical stimulation was mainly used to either increase perilesional excitability or reduce contralesional activity based on the concept of reciprocal inhibition and maladaptive plasticity. However, recent studies also showed some positive effects of the reinforcement of neural activities in the contralateral right hemisphere, based on the potential compensatory role of the nondominant hemisphere in stroke recovery. PMID:23002940

  5. Development of Cortical Circuitry and Cognitive Function.

    ERIC Educational Resources Information Center

    Goldman-Rakic, Patricia S.

    1987-01-01

    Recent studies on the biological development of the prefrontal cortex in rhesus monkeys are reviewed. These studies have elucidated the basic neural circuitry underlying the delayed-response function in adult nonhuman primates and suggest that a critical mass of cortical synapses is important for the emergence of this cognitive function. (BN)

  6. The Teaching and the Learning Brain: A Cortical Hemodynamic Marker of Teacher-Student Interactions in the Socratic Dialog

    ERIC Educational Resources Information Center

    Holper, Lisa; Goldin, Andrea P.; Shalom, Diego E.; Battro, Antonio M.; Wolf, Martin; Sigman, Mariano

    2013-01-01

    The study aimed to step into two-person (teacher-student) educational neuroscience. We describe a physiological marker of cortical hemodynamic correlates involved in teacher-student interactions during performance of a classical teaching model, the Socratic dialog. We recorded prefrontal brain activity during dialog execution simultaneously in…

  7. CORTICAL EVENT-RELATED POTENTIALS TO SPEECH SOUNDS IN 3- MONTH OLD BREAST AND FORMULA-FED INFANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies showing that infants can differentially process and discriminate speech stimuli have not considered the influence of diet as an experimental variable. To investigate this relationship, cortical auditory evoked potentials (ERPs) to syllables were recorded (128 electrodes) from 3 month old inf...

  8. Localization of metastatic adrenal cortical carcinoma with Ga-67

    SciTech Connect

    Ward, F.T.; Anderson, J.H.; Jelinek, J.; Anderson, D.W. )

    1991-02-01

    Data are limited on the localization of Ga-67 in primary or metastatic adrenal cortical carcinoma. We report the localization of Ga-67 to pathologically confirmed adrenal cortical carcinoma metastatic to the lung. A review of the literature revealed four patients have previously been reported to have metastatic adrenal cortical carcinoma detected on Ga-67 scan. Gallium imaging may be useful in the evaluation of patients with adrenal cortical carcinoma. SPECT imaging should further improve lesion resolution and localization.

  9. The Non-Benzodiazepine Hypnotic Zolpidem Impairs Sleep-Dependent Cortical Plasticity

    PubMed Central

    Seibt, Julie; Aton, Sara J.; Jha, Sushil K.; Coleman, Tammi; Dumoulin, Michelle C.; Frank, Marcos G.

    2008-01-01

    Study Objectives: The effects of hypnotics on sleep-dependent brain plasticity are unknown. We have shown that sleep enhances a canonical model of in vivo cortical plasticity, known as ocular dominance plasticity (ODP). We investigated the effects of 3 different classes of hypnotics on ODP. Design: Polysomnographic recordings were performed during the entire experiment (20 h). After a baseline sleep/wake recording (6 h), cats received 6 h of monocular deprivation (MD) followed by an i.p. injection of triazolam (1–10 mg/kg i.p.), zolpidem (10 mg/kg i.p.), ramelteon (0.1–1 mg/kg i.p.), or vehicle (DMSO i.p.). They were then allowed to sleep ad lib for 8 h, after which they were prepared for optical imaging of intrinsic cortical signals and single-unit electrophysiology. Setting: Basic neurophysiology laboratory Patients or Participants: Cats (male and female) in the critical period of visual development (postnatal days 28–41) Interventions: N/A Measurements and Results: Zolpidem reduced cortical plasticity by ∼50% as assessed with optical imaging of intrinsic cortical signals. This was not due to abnormal sleep architecture because triazolam, which perturbed sleep architecture and sleep EEGs more profoundly than zolpidem, had no effect on plasticity. Ramelteon minimally altered sleep and had no effect on ODP. Conclusions: Our findings demonstrate that alterations in sleep architecture do not necessarily lead to impairments in sleep function. Conversely, hypnotics that produce more “physiological” sleep based on polysomnography may impair critical brain processes, depending on their pharmacology. Citation: Seibt J; Aton SJ; Jha SK; Coleman T; Dumoulin MC; Frank MG. The non-benzodiazepine hypnotic zolpidem impairs sleep-dependent cortical plasticity. SLEEP 2008;31(10):1381–1391. PMID:18853935

  10. Trajectories of cortical surface area and cortical volume maturation in normal brain development

    PubMed Central

    Ducharme, Simon; Albaugh, Matthew D.; Nguyen, Tuong-Vi; Hudziak, James J.; Mateos-Pérez, J.M.; Labbe, Aurelie; Evans, Alan C.; Karama, Sherif

    2015-01-01

    This is a report of developmental trajectories of cortical surface area and cortical volume in the NIH MRI Study of Normal Brain Development. The quality-controlled sample included 384 individual typically-developing subjects with repeated scanning (1–3 per subject, total scans n=753) from 4.9 to 22.3 years of age. The best-fit model (cubic, quadratic, or first-order linear) was identified at each vertex using mixed-effects models, with statistical correction for multiple comparisons using random field theory. Analyses were performed with and without controlling for total brain volume. These data are provided for reference and comparison with other databases. Further discussion and interpretation on cortical developmental trajectories can be found in the associated Ducharme et al.׳s article “Trajectories of cortical thickness maturation in normal brain development – the importance of quality control procedures” (Ducharme et al., 2015) [1]. PMID:26702424

  11. Three-dimensional localization of cortical electrodes in deep brain stimulation surgery from intraoperative fluoroscopy.

    PubMed

    Randazzo, Michael J; Kondylis, Efstathios D; Alhourani, Ahmad; Wozny, Thomas A; Lipski, Witold J; Crammond, Donald J; Richardson, R Mark

    2016-01-15

    Electrophysiological recordings from subdural electrocorticography (ECoG) electrodes implanted temporarily during deep brain stimulation (DBS) surgeries offer a unique opportunity to record cortical activity for research purposes. The optimal utilization of this important research method relies on accurate and robust localization of ECoG electrodes, and intraoperative fluoroscopy is often the only imaging modality available to visualize electrode locations. However, the localization of a three-dimensional electrode position using a two-dimensional fluoroscopic image is problematic due to the lost dimension orthogonal to the fluoroscopic image, a parallax distortion implicit to fluoroscopy, and variability of visible skull contour among fluoroscopic images. Here, we present a method to project electrodes visible on the fluoroscopic image onto a reconstructed cortical surface by leveraging numerous common landmarks to translate, rotate, and scale coregistered computed tomography (CT) and magnetic resonance imaging (MRI) reconstructed surfaces in order to recreate the coordinate framework in which the fluoroscopic image was acquired, while accounting for parallax distortion. Validation of this approach demonstrated high precision with an average total Euclidian distance between three independent reviewers of 1.65±0.68mm across 8 patients and 82 electrodes. Spatial accuracy was confirmed by correspondence between recorded neural activity over sensorimotor cortex during hand movement. This semi-automated interface reliably estimates the location of temporarily implanted subdural ECoG electrodes visible on intraoperative fluoroscopy to a cortical surface. PMID:26520771

  12. Revisiting enigmatic cortical calretinin-expressing interneurons

    PubMed Central

    Cauli, Bruno; Zhou, Xiaojuan; Tricoire, Ludovic; Toussay, Xavier; Staiger, Jochen F.

    2014-01-01

    Cortical calretinin (CR)-expressing interneurons represent a heterogeneous subpopulation of about 10–30% of GABAergic interneurons, which altogether total ca. 12–20% of all cortical neurons. In the rodent neocortex, CR cells display different somatodendritic morphologies ranging from bipolar to multipolar but the bipolar cells and their variations dominate. They are also diverse at the molecular level as they were shown to express numerous neuropeptides in different combinations including vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK), neurokinin B (NKB) corticotrophin releasing factor (CRF), enkephalin (Enk) but also neuropeptide Y (NPY) and somatostatin (SOM) to a lesser extent. CR-expressing interneurons exhibit different firing behaviors such as adapting, bursting or irregular. They mainly originate from the caudal ganglionic eminence (CGE) but a subpopulation also derives from the dorsal part of the medial ganglionic eminence (MGE). Cortical GABAergic CR-expressing interneurons can be divided in two main populations: VIP-bipolar interneurons deriving from the CGE and SOM-Martinotti-like interneurons originating in the dorsal MGE. Although bipolar cells account for the majority of CR-expressing interneurons, the roles they play in cortical neuronal circuits and in the more general metabolic physiology of the brain remained elusive and enigmatic. The aim of this review is, firstly, to provide a comprehensive view of the morphological, molecular and electrophysiological features defining this cell type. We will, secondly, also summarize what is known about their place in the cortical circuit, their modulation by subcortical afferents and the functional roles they might play in neuronal processing and energy metabolism. PMID:25009470

  13. CORTICAL INVOLVEMENT IN THE STARTREACT EFFECT

    PubMed Central

    Stevenson, Andrew J. T.; Chiu, Chenhao; Maslovat, Dana; Chua, Romeo; Gick, Bryan; Blouin, Jean-Sébastien; Franks, Ian M.

    2014-01-01

    The rapid release of prepared movements by a loud acoustic stimulus capable of eliciting a startle response has been termed the StartReact effect (Valls-Solé et al., 1999), and premotor reaction times (PMTs) of <70 ms are often observed. Two explanations have been given for these short latency responses. The subcortical storage and triggering hypothesis suggests movements that can be prepared in advance of a “go” signal are stored and triggered from subcortical areas by a startling acoustic stimulus (SAS) without cortical involvement. Alternatively, it has been hypothesized that the SAS can trigger movements from cortical areas through a faster pathway ascending from subcortical structures. Two experiments were designed to examine the possible role of primary motor cortex in the StartReact effect. In Experiment 1, we used suprathreshold transcranial magnetic stimulation (TMS) during the reaction time (RT) interval to induce a cortical silent period in the contralateral primary motor cortex (M1). Thirteen participants performed 20° wrist extension movements as fast as possible in response to either a control stimulus (82dB) or SAS (124 dB). PMTs for startle trials were faster than control trials, while TMS significantly delayed movement onset compared to No TMS or Sham TMS conditions. In Experiment 2, we examined the StartReact effect in a highly cortically represented action involving speech of a consonant-vowel (CV) syllable. Similar to previous work examining limb movements, a robust StartReact effect was found. Collectively, these experiments provide evidence for cortical (M1) involvement in the StartReact effect. PMID:24680855

  14. Variability in Cortical Representations of Speech Sound Perception

    ERIC Educational Resources Information Center

    Boatman, Dana F.

    2007-01-01

    Recent brain mapping studies have provided new insights into the cortical systems that mediate human speech perception. Electrocortical stimulation mapping (ESM) is a brain mapping method that is used clinically to localize cortical functions in neurosurgical patients. Recent ESM studies have yielded new insights into the cortical systems that…

  15. Social Suppressive Behavior Is Organized by the Spatiotemporal Integration of Multiple Cortical Regions in the Japanese Macaque.

    PubMed

    Oosugi, Naoya; Yanagawa, Toru; Nagasaka, Yasuo; Fujii, Naotaka

    2016-01-01

    Under social conflict, monkeys develop hierarchical positions through social interactions. Once the hierarchy is established, the dominant monkey dominates the space around itself and the submissive monkey tries not to violate this space. Previous studies have shown the contributions of the frontal and parietal cortices in social suppression, but the contributions of other cortical areas to suppressive functions remain elusive. We recorded neural activity in large cortical areas using electrocorticographic (ECoG) arrays while monkeys performed a social food-grab task in which a target monkey was paired with either a dominant or a submissive monkey. If the paired monkey was dominant, the target monkey avoided taking food in the shared conflict space, but not in other areas. By contrast, when the paired monkey was submissive, the target monkey took the food freely without hesitation. We applied decoding analysis to the ECoG data to see when and which cortical areas contribute to social behavioral suppression. Neural information discriminating the social condition was more evident when the conflict space was set in the area contralateral to the recording hemisphere. We found that the information increased as the social pressure increased during the task. Before food presentation, when the pressure was relatively low, the parietal and somatosensory-motor cortices showed sustained discrimination of the social condition. After food presentation, when the monkey faced greater pressure to make a decision as to whether it should take the food, the prefrontal and visual cortices started to develop buildup responses. The social representation was found in a sustained form in the parietal and somatosensory-motor regions, followed by additional buildup form in the visual and prefrontal cortices. The representation was less influenced by reward expectation. These findings suggest that social adaptation is achieved by a higher-order self-regulation process (incorporating motor

  16. Social Suppressive Behavior Is Organized by the Spatiotemporal Integration of Multiple Cortical Regions in the Japanese Macaque

    PubMed Central

    Nagasaka, Yasuo; Fujii, Naotaka

    2016-01-01

    Under social conflict, monkeys develop hierarchical positions through social interactions. Once the hierarchy is established, the dominant monkey dominates the space around itself and the submissive monkey tries not to violate this space. Previous studies have shown the contributions of the frontal and parietal cortices in social suppression, but the contributions of other cortical areas to suppressive functions remain elusive. We recorded neural activity in large cortical areas using electrocorticographic (ECoG) arrays while monkeys performed a social food-grab task in which a target monkey was paired with either a dominant or a submissive monkey. If the paired monkey was dominant, the target monkey avoided taking food in the shared conflict space, but not in other areas. By contrast, when the paired monkey was submissive, the target monkey took the food freely without hesitation. We applied decoding analysis to the ECoG data to see when and which cortical areas contribute to social behavioral suppression. Neural information discriminating the social condition was more evident when the conflict space was set in the area contralateral to the recording hemisphere. We found that the information increased as the social pressure increased during the task. Before food presentation, when the pressure was relatively low, the parietal and somatosensory–motor cortices showed sustained discrimination of the social condition. After food presentation, when the monkey faced greater pressure to make a decision as to whether it should take the food, the prefrontal and visual cortices started to develop buildup responses. The social representation was found in a sustained form in the parietal and somatosensory–motor regions, followed by additional buildup form in the visual and prefrontal cortices. The representation was less influenced by reward expectation. These findings suggest that social adaptation is achieved by a higher-order self-regulation process (incorporating

  17. Cortical dynamics of word recognition.

    PubMed

    Mainy, Nelly; Jung, Julien; Baciu, Monica; Kahane, Philippe; Schoendorff, Benjamin; Minotti, Lorella; Hoffmann, Dominique; Bertrand, Olivier; Lachaux, Jean-Philippe

    2008-11-01

    While functional neuroimaging studies have helped elucidate major regions implicated in word recognition, much less is known about the dynamics of the associated activations or the actual neural processes of their functional network. We used intracerebral electroencephalography recordings in 10 patients with epilepsy to directly measure neural activity in the temporal and frontal lobes during written words' recognition, predominantly in the left hemisphere. The patients were presented visually with consonant strings, pseudo-words, and words and performed a hierarchical paradigm contrasting semantic processes (living vs. nonliving word categorization task), phonological processes (rhyme decision task on pseudo-words), and visual processes (visual analysis of consonant strings). Stimuli triggered a cascade of modulations in the gamma-band (>40 Hz) with reproducible timing and task-sensitivity throughout the functional reading network: the earliest gamma-band activations were observed for all stimuli in the mesial basal temporal lobe at 150 ms, reaching the word form area in the mid fusiform gyrus at 200 ms, evidencing a superiority effect for word-like stimuli. Peaks of gamma-band activations were then observed for word-like stimuli after 400 ms in the anterior and middle portion of the superior temporal gyrus (BA 38 and BA 22 respectively), in the pars triangularis of Broca's area for the semantic task (BAs 45 and 47), and in the pars opercularis for the phonological task (BA 44). Concurrently, we observed a two-pronged effect in the prefrontal cortex (BAs 9 and 46), with nonspecific sustained dorsal activation related to sustained attention and, more ventrally, a strong reflex deactivation around 500 ms, possibly due to semantic working memory reset. PMID:17712785

  18. Cortical responses to consciousness of schematic emotional facial expressions: a high-resolution EEG study.

    PubMed

    Babiloni, Claudio; Vecchio, Fabrizio; Buffo, Paola; Buttiglione, Maura; Cibelli, Giuseppe; Rossini, Paolo Maria

    2010-10-01

    Is conscious perception of emotional face expression related to enhanced cortical responses? Electroencephalographic data (112 channels) were recorded in 15 normal adults during the presentation of cue stimuli with neutral, happy or sad schematic faces (duration: "threshold time" inducing about 50% of correct recognitions), masking stimuli (2 s), and go stimuli with happy or sad schematic faces (0.5 s). The subjects clicked left (right) mouse button in response to go stimuli with happy (sad) faces. After the response, they said "seen" or "not seen" with reference to previous cue stimulus. Electroencephalographic data formed visual event-related potentials (ERPs). Cortical sources of ERPs were estimated by LORETA software. Reaction time to go stimuli was generally shorter during "seen" than "not seen" trials, possibly due to covert attention and awareness. The cue stimuli evoked four ERP components (posterior N100, N170, P200, and P300), which had similar peak latency in the "not seen" and "seen" ERPs. Only N170 amplitude showed differences in amplitude in the "seen" versus "not seen" ERPs. Compared to the "not seen" ERPs, the "seen" ones showed prefrontal, premotor, and posterior parietal sources of N170 higher in amplitude with the sad cue stimuli and lower in amplitude with the neutral and happy cue stimuli. These results suggest that nonconscious and conscious processing of schematic emotional facial expressions shares a similar temporal evolution of cortical activity, and conscious processing induces an early enhancement of bilateral cortical activity for the schematic sad facial expressions (N170). PMID:20143385

  19. Cortical hypoexcitation defines neuronal responses in the immediate aftermath of traumatic brain injury.

    PubMed

    Johnstone, Victoria Philippa Anne; Yan, Edwin Bingbing; Alwis, Dasuni Sathsara; Rajan, Ramesh

    2013-01-01

    Traumatic brain injury (TBI) from a blow to the head is often associated with complex patterns of brain abnormalities that accompany deficits in cognitive and motor function. Previously we reported that a long-term consequence of TBI, induced with a closed-head injury method modelling human car and sporting accidents, is neuronal hyper-excitation in the rat sensory barrel cortex that receives tactile input from the face whiskers. Hyper-excitation occurred only in supra-granular layers and was stronger to complex than simple stimuli. We now examine changes in the immediate aftermath of TBI induced with same injury method. At 24 hours post-trauma significant sensorimotor deficits were observed and characterisation of the cortical population neuronal responses at that time revealed a depth-dependent suppression of neuronal responses, with reduced responses from supragranular layers through to input layer IV, but not in infragranular layers. In addition, increased spontaneous firing rate was recorded in cortical layers IV and V. We postulate that this early post-injury suppression of cortical processing of sensory input accounts for immediate post-trauma sensory morbidity and sets into train events that resolve into long-term cortical hyper-excitability in upper sensory cortex layers that may account for long-term sensory hyper-sensitivity in humans with TBI. PMID:23667624

  20. High-spatial-resolution mapping of the oxygen concentration in cortical tissue (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jaswal, Rajeshwer S.; Yaseen, Mohammad A.; Fu, Buyin; Boas, David A.; Sakadžic, Sava

    2016-03-01

    Due to a lack of imaging tools for high-resolution imaging of cortical tissue oxygenation, the detailed maps of the oxygen partial pressure (PO2) around arterioles, venules, and capillaries remain largely unknown. Therefore, we have limited knowledge about the mechanisms that secure sufficient oxygen delivery in microvascular domains during brain activation, and provide some metabolic reserve capacity in diseases that affect either microvascular networks or the regulation of cerebral blood flow (CBF). To address this challenge, we applied a Two-Photon PO2 Microscopy to map PO2 at different depths in mice cortices. Measurements were performed through the cranial window in the anesthetized healthy mice as well as in the mouse models of microvascular dysfunctions. In addition, microvascular morphology was recorded by the two-photon microscopy at the end of each experiment and subsequently segmented. Co-registration of the PO2 measurements and exact microvascular morphology enabled quantification of the tissue PO2 dependence on distance from the arterioles, capillaries, and venules at various depths. Our measurements reveal significant spatial heterogeneity of the cortical tissue PO2 distribution that is dominated by the high oxygenation in periarteriolar spaces. In cases of impaired oxygen delivery due to microvascular dysfunction, significant reduction in tissue oxygenation away from the arterioles was observed. These tissue domains may be the initial sites of cortical injury that can further exacerbate the progression of the disease.

  1. Dampened hippocampal oscillations and enhanced spindle activity in an asymptomatic model of developmental cortical malformations

    PubMed Central

    Cid, Elena; Gomez-Dominguez, Daniel; Martin-Lopez, David; Gal, Beatriz; Laurent, François; Ibarz, Jose M.; Francis, Fiona; Menendez de la Prida, Liset

    2014-01-01

    Developmental cortical malformations comprise a large spectrum of histopathological brain abnormalities and syndromes. Their genetic, developmental and clinical complexity suggests they should be better understood in terms of the complementary action of independently timed perturbations (i.e., the multiple-hit hypothesis). However, understanding the underlying biological processes remains puzzling. Here we induced developmental cortical malformations in offspring, after intraventricular injection of methylazoxymethanol (MAM) in utero in mice. We combined extensive histological and electrophysiological studies to characterize the model. We found that MAM injections at E14 and E15 induced a range of cortical and hippocampal malformations resembling histological alterations of specific genetic mutations and transplacental mitotoxic agent injections. However, in contrast to most of these models, intraventricularly MAM-injected mice remained asymptomatic and showed no clear epilepsy-related phenotype as tested in long-term chronic recordings and with pharmacological manipulations. Instead, they exhibited a non-specific reduction of hippocampal-related brain oscillations (mostly in CA1); including theta, gamma and HFOs; and enhanced thalamocortical spindle activity during non-REM sleep. These data suggest that developmental cortical malformations do not necessarily correlate with epileptiform activity. We propose that the intraventricular in utero MAM approach exhibiting a range of rhythmopathies is a suitable model for multiple-hit studies of associated neurological disorders. PMID:24782720

  2. Early deficits in cortical control of swallowing in Alzheimer’s disease

    PubMed Central

    Humbert, Ianessa A.; McLaren, Donald G.; Kosmatka, Kris; Fitzgerald, Michelle; Johnson, Sterling; Porcaro, Eva; Kays, Stephanie; Umoh, Eno-Obong; Robbins, JoAnne

    2010-01-01

    The goal of this study was to determine whether functional changes in cortical control of swallowing are evident in early Alzheimer’s disease (AD), before dysphagia (swallowing impairment) is evident. Cortical function was compared between an early AD group and a group of age-matched controls during swallowing. Swallowing oropharyngeal biomechanics examined from videofluoroscopic recordings were also obtained to more comprehensively characterize changes in swallowing associated with early AD. Our neuroimaging results show that the AD group had significantly lower BOLD response in many cortical areas that are traditionally involved in normal swallowing (i.e. pre and postcentral gyri, Rolandic and frontal opercula). There were no regions where the AD group recruited more brain activity than the healthy controls during swallowing and only 13% of all active voxels were unique to the AD group, even at this early stage. This suggests that the AD group is not recruiting new regions, nor are they compensating within regions that are active during swallowing. In videofluoroscopic measures, the AD group had significantly reduced hyo-laryngeal elevation than the controls. Although, swallowing impairment is usually noted in the late stages of AD, changes in cortical control of swallowing may begin long before dysphagia becomes apparent. PMID:20308785

  3. Relaxed genetic control of cortical organization in human brains compared with chimpanzees

    PubMed Central

    Gómez-Robles, Aida; Hopkins, William D.; Schapiro, Steven J.; Sherwood, Chet C.

    2015-01-01

    The study of hominin brain evolution has focused largely on the neocortical expansion and reorganization undergone by humans as inferred from the endocranial fossil record. Comparisons of modern human brains with those of chimpanzees provide an additional line of evidence to define key neural traits that have emerged in human evolution and that underlie our unique behavioral specializations. In an attempt to identify fundamental developmental differences, we have estimated the genetic bases of brain size and cortical organization in chimpanzees and humans by studying phenotypic similarities between individuals with known kinship relationships. We show that, although heritability for brain size and cortical organization is high in chimpanzees, cerebral cortical anatomy is substantially less genetically heritable than brain size in humans, indicating greater plasticity and increased environmental influence on neurodevelopment in our species. This relaxed genetic control on cortical organization is especially marked in association areas and likely is related to underlying microstructural changes in neural circuitry. A major result of increased plasticity is that the development of neural circuits that underlie behavior is shaped by the environmental, social, and cultural context more intensively in humans than in other primate species, thus providing an anatomical basis for behavioral and cognitive evolution. PMID:26627234

  4. Relaxed genetic control of cortical organization in human brains compared with chimpanzees.

    PubMed

    Gómez-Robles, Aida; Hopkins, William D; Schapiro, Steven J; Sherwood, Chet C

    2015-12-01

    The study of hominin brain evolution has focused largely on the neocortical expansion and reorganization undergone by humans as inferred from the endocranial fossil record. Comparisons of modern human brains with those of chimpanzees provide an additional line of evidence to define key neural traits that have emerged in human evolution and that underlie our unique behavioral specializations. In an attempt to identify fundamental developmental differences, we have estimated the genetic bases of brain size and cortical organization in chimpanzees and humans by studying phenotypic similarities between individuals with known kinship relationships. We show that, although heritability for brain size and cortical organization is high in chimpanzees, cerebral cortical anatomy is substantially less genetically heritable than brain size in humans, indicating greater plasticity and increased environmental influence on neurodevelopment in our species. This relaxed genetic control on cortical organization is especially marked in association areas and likely is related to underlying microstructural changes in neural circuitry. A major result of increased plasticity is that the development of neural circuits that underlie behavior is shaped by the environmental, social, and cultural context more intensively in humans than in other primate species, thus providing an anatomical basis for behavioral and cognitive evolution. PMID:26627234

  5. Viewing a forelimb induces widespread cortical activations.

    PubMed

    Raos, Vassilis; Kilintari, Marina; Savaki, Helen E

    2014-04-01

    Given that prerequisite of activating the mirror neuron system is the preshaping of the hand and its interaction with the object during observation of a reaching-to-grasp-an-object action, the effects of viewing the object, the reaching forelimb and the static hand may obscure the effects of observing the grasping action per se. To disentangle these effects, we employed the (14)C-deoxyglucose quantitative autoradiographic method to map the functional activity in the entire cortex of monkeys (Macaca mulatta) which observed the experimenter performing non-goal-directed (purposeless) forelimb movements towards an object that was previously presented but no longer visible. Thus, our monkeys were exposed to the view of an object, a moving arm and a static hand with extended wrist and fingers. The distribution of metabolic activity was analyzed in 20μm thick brain sections, and two dimensional maps were reconstructed in the occipital operculum, the temporal, the lateral and medial parietal, the lateral and medial frontal, the lateral prefrontal and orbitofrontal cortices, including the cortex within the lunate, superior temporal, lateral, parietoccipital, intraparietal, central, arcuate and principal sulci. Increased metabolic activity, as compared to fixation-control monkeys, was measured in the forelimb representation of the primary motor and somatosensory cortices, the premotor cortices F2 and F5, cingulate motor areas, the secondary somatosensory cortex SII, the posterior intraparietal area 5 and areas TPOc and FST, in the hemisphere contralateral to the moving arm. Moreover, bilateral activations were elicited in areas pre-SMA, 8m, SSA and the somatorecipient area VS, the retroinsula, the auditory belt area CM, motion areas MT, MST, LOP/CIP, area 31, visual areas TEO, V6, V6Av and the parafoveal and peripheral visual representations of areas V1 and V2, respectively. Few parietal, auditory and visual areas were bilaterally depressed. In brief, a surprisingly wide

  6. Serotonin modulation of cortical neurons and networks

    PubMed Central

    Celada, Pau; Puig, M. Victoria; Artigas, Francesc

    2013-01-01

    The serotonergic pathways originating in the dorsal and median raphe nuclei (DR and MnR, respectively) are critically involved in cortical function. Serotonin (5-HT), acting on postsynaptic and presynaptic receptors, is involved in cognition, mood, impulse control and motor functions by (1) modulating the activity of different neuronal types, and (2) varying the release of other neurotransmitters, such as glutamate, GABA, acetylcholine and dopamine. Also, 5-HT seems to play an important role in cortical development. Of all cortical regions, the frontal lobe is the area most enriched in serotonergic axons and 5-HT receptors. 5-HT and selective receptor agonists modulate the excitability of cortical neurons and their discharge rate through the activation of several receptor subtypes, of which the 5-HT1A, 5-HT1B, 5-HT2A, and 5-HT3 subtypes play a major role. Little is known, however, on the role of other excitatory receptors moderately expressed in cortical areas, such as 5-HT2C, 5-HT4, 5-HT6, and 5-HT7. In vitro and in vivo studies suggest that 5-HT1A and 5-HT2A receptors are key players and exert opposite effects on the activity of pyramidal neurons in the medial prefrontal cortex (mPFC). The activation of 5-HT1A receptors in mPFC hyperpolarizes pyramidal neurons whereas that of 5-HT2A receptors results in neuronal depolarization, reduction of the afterhyperpolarization and increase of excitatory postsynaptic currents (EPSCs) and of discharge rate. 5-HT can also stimulate excitatory (5-HT2A and 5-HT3) and inhibitory (5-HT1A) receptors in GABA interneurons to modulate synaptic GABA inputs onto pyramidal neurons. Likewise, the pharmacological manipulation of various 5-HT receptors alters oscillatory activity in PFC, suggesting that 5-HT is also involved in the control of cortical network activity. A better understanding of the actions of 5-HT in PFC may help to develop treatments for mood and cognitive disorders associated with an abnormal function of the frontal lobe

  7. On the relationship between joint angular velocity and motor cortical discharge during reaching.

    PubMed

    Reina, G A; Moran, D W; Schwartz, A B

    2001-06-01

    Single-unit activity in area M1 was recorded in awake, behaving monkeys during a three-dimensional (3D) reaching task performed in a virtual reality environment. This study compares motor cortical discharge rate to both the hand's velocity and the arm's joint angular velocities. Hand velocity is considered a parameter of extrinsic space because it is measured in the Cartesian coordinate system of the monkey's workspace. Joint angular velocity is considered a parameter of intrinsic space because it is measured relative to adjacent arm/body segments. In the initial analysis, velocity was measured as the difference in hand position or joint posture between the beginning and ending of the reach. Cortical discharge rate was taken as the mean activity between these two times. This discharge rate was compared through a regression analysis to either an extrinsic-coordinate model based on the three components of hand velocity or to an intrinsic-coordinate model based on seven joint angular velocities. The model showed that velocities about four degrees-of-freedom (elbow flexion/extension, shoulder flexion/extension, shoulder internal/external rotation, and shoulder adduction/abduction) were those best represented in the sampled population of recorded activity. Patterns of activity recorded across the cortical population at each point in time throughout the task were used in a second analysis to predict the temporal profiles of joint angular velocity and hand velocity. The population of cortical units from area M1 matched the hand velocity and three of the four major joint angular velocities. However, shoulder adduction/abduction could not be predicted even though individual cells showed good correlation to movement on this axis. This was also the only major degree-of-freedom not well correlated to hand velocity, suggesting that the other apparent relations between joint angular velocity and neuronal activity may be due to intrinsic-extrinsic correlations inherent in

  8. Altered cortical activity in prelingually deafened cochlear implant users following long periods of auditory deprivation.

    PubMed

    Lammers, Marc J W; Versnel, Huib; van Zanten, Gijsbert A; Grolman, Wilko

    2015-02-01

    Auditory stimulation during childhood is critical for the development of the auditory cortex in humans and with that for hearing in adulthood. Age-related changes in morphology and peak latencies of the cortical auditory evoked potential (CAEP) have led to the use of this cortical response as a biomarker of auditory cortical maturation including studies of cortical development after deafness and subsequent cochlear implantation. To date, it is unknown whether prelingually deaf adults, with early onset deafness (before the age of 2 years) and who received a cochlear implant (CI) only during adulthood, would display absent or aberrant CAEP waveforms as predicted from CAEP studies in late implanted prelingually deaf children. In the current study, CAEP waveforms were recorded in response to electric stimuli in prelingually deaf adults, who received their CI after the age of 21 years. Waveform morphology and peak latencies were compared to the CAEP responses obtained in postlingually deaf adults, who became deaf after the age of 16. Unexpectedly, typical CAEP waveforms with adult-like P1-N1-P2 morphology could be recorded in the prelingually deaf adult CI users. On visual inspection, waveform morphology was comparable to the CAEP waveforms recorded in the postlingually deaf CI users. Interestingly, however, latencies of the N1 peak were significantly shorter and amplitudes were significantly larger in the prelingual group than in the postlingual group. The presence of the CAEP together with an early and large N1 peak might represent activation of the more innate and less complex components of the auditory cortex of the prelingually deaf CI user, whereas the CAEP in postlingually deaf CI users might reflect activation of the mature neural network still present in these patients. The CAEPs may therefore be helpful in the assessment of developmental state of the auditory cortex. PMID:25315357

  9. Helical recorder

    NASA Technical Reports Server (NTRS)

    Cole, P. T.; Studer, P. A.; Tyler, A. L.

    1969-01-01

    Tape recorder, using metallic tape, has a minimum of moving parts and no belts. It permits long-term bulk storage in extreme environments, and has less weight and bulk than present recording equipment.

  10. Genetic animal models of malformations of cortical development and epilepsy.

    PubMed

    Wong, Michael; Roper, Steven N

    2016-02-15

    Malformations of cortical development constitute a variety of pathological brain abnormalities that commonly cause severe, medically-refractory epilepsy, including focal lesions, such as focal cortical dysplasia, heterotopias, and tubers of tuberous sclerosis complex, and diffuse malformations, such as lissencephaly. Although some cortical malformations result from environmental insults during cortical development in utero, genetic factors are increasingly recognized as primary pathogenic factors across the entire spectrum of malformations. Genes implicated in causing different cortical malformations are involved in a variety of physiological functions, but many are focused on regulation of cell proliferation, differentiation, and neuronal migration. Advances in molecular genetic methods have allowed the engineering of increasingly sophisticated animal models of cortical malformations and associated epilepsy. These animal models have identified some common mechanistic themes shared by a number of different cortical malformations, but also revealed the diversity and complexity of cellular and molecular mechanisms that lead to the development of the pathological lesions and resulting epileptogenesis. PMID:25911067

  11. Inhibitory interneurons in visual cortical plasticity.

    PubMed

    van Versendaal, Daniëlle; Levelt, Christiaan N

    2016-10-01

    For proper maturation of the neocortex and acquisition of specific functions and skills, exposure to sensory stimuli is vital during critical periods of development when synaptic connectivity is highly malleable. To preserve reliable cortical processing, it is essential that these critical periods end after which learning becomes more conditional and active interaction with the environment becomes more important. How these age-dependent forms of plasticity are regulated has been studied extensively in the primary visual cortex. This has revealed that inhibitory innervation plays a crucial role and that a temporary decrease in inhibition is essential for plasticity to take place. Here, we discuss how different interneuron subsets regulate plasticity during different stages of cortical maturation. We propose a theory in which different interneuron subsets select the sources of neuronal input that undergo plasticity. PMID:27193323

  12. Permanent Cortical Blindness After Bronchial Artery Embolization

    SciTech Connect

    Doorn, Colette S. van De Boo, Diederick W.; Weersink, Els J. M.; Delden, Otto M. van Reekers, Jim A. Lienden, Krijn P. van

    2013-12-15

    A 35-year-old female with a known medical history of cystic fibrosis was admitted to our institution for massive hemoptysis. CTA depicted a hypertrophied bronchial artery to the right upper lobe and showed signs of recent bleeding at that location. Bronchial artery embolization (BAE) was performed with gelfoam slurry, because pronounced shunting to the pulmonary artery was present. Immediately after BAE, the patient developed bilateral cortical blindness. Control angiography showed an initially not opacified anastomosis between the embolized bronchial artery and the right subclavian artery, near to the origin of the right vertebral artery. Cessation of outflow in the bronchial circulation reversed the flow through the anastomosis and allowed for spill of embolization material into the posterior circulation. Unfortunately the cortical blindness presented was permanent.

  13. Relearning to See in Cortical Blindness.

    PubMed

    Melnick, Michael D; Tadin, Duje; Huxlin, Krystel R

    2016-04-01

    The incidence of cortically induced blindness is increasing as our population ages. The major cause of cortically induced blindness is stroke affecting the primary visual cortex. While the impact of this form of vision loss is devastating to quality of life, the development of principled, effective rehabilitation strategies for this condition lags far behind those used to treat motor stroke victims. Here we summarize recent developments in the still emerging field of visual restitution therapy, and compare the relative effectiveness of different approaches. We also draw insights into the properties of recovered vision, its limitations and likely neural substrates. We hope that these insights will guide future research and bring us closer to the goal of providing much-needed rehabilitation solutions for this patient population. PMID:26659828

  14. Unified statistical approach to cortical thickness analysis.

    PubMed

    Chung, Moo K; Robbins, Steve; Evans, Alan C

    2005-01-01

    This paper presents a unified image processing and analysis framework for cortical thickness in characterizing a clinical population. The emphasis is placed on the development of data smoothing and analysis framework. The human brain cortex is a highly convoluted surface. Due to the convoluted non-Euclidean surface geometry, data smoothing and analysis on the cortex are inherently difficult. When measurements lie on a curved surface, it is natural to assign kernel smoothing weights based on the geodesic distance along the surface rather than the Euclidean distance. We present a new data smoothing framework that address this problem implicitly without actually computing the geodesic distance and present its statistical properties. Afterwards, the statistical inference is based on the random field theory based multiple comparison correction. As an illustration, we have applied the method in detecting the regions of abnormal cortical thickness in 16 high functioning autistic children. PMID:17354731

  15. Cortical laminar necrosis following myocardial infarction.

    PubMed

    Lattanzi, Simona; Silvestrini, Mauro; Provinciali, Leandro

    2016-01-01

    The cortical laminar necrosis (CLN) is a permanent injury characterized by the selective delayed necrosis of the cerebral cortex, mainly of the third layer, and usually greater in the depths and sides of the sulci than over the crest of the gyri. The damage involves all cellular components - either neurons, glia cells and blood vessels - and results in a focal cortical band of pan-necrosis detectable in late sub-acute or chronic stages of reduced energy supply to the brain. The CLN has been described in different conditions as hypoxia, hypoglycemia and status epilepticus. At brain CT or MR scans it appears with pathognomonic highly hyperdense or T1-hyperintense lesions following the gyral anatomy of the cerebral cortex. We reported a case of CLN associated to myocardial infarct and discussed the underlying mechanisms. PMID:27375142

  16. Phonological Processing in Human Auditory Cortical Fields

    PubMed Central

    Woods, David L.; Herron, Timothy J.; Cate, Anthony D.; Kang, Xiaojian; Yund, E. W.

    2011-01-01

    We used population-based cortical-surface analysis of functional magnetic imaging data to characterize the processing of consonant–vowel–consonant syllables (CVCs) and spectrally matched amplitude-modulated noise bursts (AMNBs) in human auditory cortex as subjects attended to auditory or visual stimuli in an intermodal selective attention paradigm. Average auditory cortical field (ACF) locations were defined using tonotopic mapping in a previous study. Activations in auditory cortex were defined by two stimulus-preference gradients: (1) Medial belt ACFs preferred AMNBs and lateral belt and parabelt fields preferred CVCs. This preference extended into core ACFs with medial regions of primary auditory cortex (A1) and the rostral field preferring AMNBs and lateral regions preferring CVCs. (2) Anterior ACFs showed smaller activations but more clearly defined stimulus preferences than did posterior ACFs. Stimulus preference gradients were unaffected by auditory attention suggesting that ACF preferences reflect the automatic processing of different spectrotemporal sound features. PMID:21541252

  17. Parcellating Cortical Functional Networks in Individuals

    PubMed Central

    Wang, Danhong; Buckner, Randy L.; Fox, Michael D.; Holt, Daphne J.; Holmes, Avram J.; Stoecklein, Sophia; Langs, Georg; Pan, Ruiqi; Qian, Tianyi; Li, Kuncheng; Baker, Justin T.; Stufflebeam, Steven M.; Wang, Kai; Wang, Xiaomin; Hong, Bo; Liu, Hesheng

    2015-01-01

    The capacity to identify the unique functional architecture of an individual’s brain is a critical step towards personalized medicine and understanding the neural basis of variations in human cognition and behavior. Here, we developed a novel cortical parcellation approach to accurately map functional organization at the individual level using resting-state fMRI. A population-based functional atlas and a map of inter-individual variability were employed to guide the iterative search for functional networks in individual subjects. Functional networks mapped by this approach were highly reproducible within subjects and effectively captured the variability across subjects, including individual differences in brain lateralization. The algorithm performed well across different subject populations and data types including task fMRI data. The approach was then validated by invasive cortical stimulation mapping in surgical patients, suggesting great potential for use in clinical applications. PMID:26551545

  18. Do Cortical Circuits Need Protecting from Themselves?

    PubMed

    Trevelyan, Andrew J

    2016-08-01

    All hippocampal and neocortical networks can be driven to seize quite easily. This can be done using drugs, by altering the ionic constituency of the bathing medium [cerebrospinal fluid (CSF)], or by electrical stimulation (both experimentally and clinically, as in electroconvulsive therapy). It is worth asking why this is so, because this will both tell us more about potentially devastating neurological disorders and extend our understanding of cortical function and architecture. Here I review work examining the features of cortical networks that bias activity towards and away from hyperexcitability. I suggest that several cellular- and circuit-level features of rapidly responsive interneuron networks tip the balance away from seizure in the healthy brain. PMID:27378547

  19. The ontogeny of the cortical language network.

    PubMed

    Skeide, Michael A; Friederici, Angela D

    2016-05-01

    Language-processing functions follow heterogeneous developmental trajectories. The human embryo can already distinguish vowels in utero, but grammatical complexity is usually not fully mastered until at least 7 years of age. Examining the current literature, we propose that the ontogeny of the cortical language network can be roughly subdivided into two main developmental stages. In the first stage extending over the first 3 years of life, the infant rapidly acquires bottom-up processing capacities, which are primarily implemented bilaterally in the temporal cortices. In the second stage continuing into adolescence, top-down processes emerge gradually with the increasing functional selectivity and structural connectivity of the left inferior frontal cortex. PMID:27040907

  20. Plasticity of Cortical Excitatory-Inhibitory Balance

    PubMed Central

    Froemke, Robert C.

    2015-01-01

    Synapses are highly plastic and are modified by changes in patterns of neural activity or sensory experience. Plasticity of cortical excitatory synapses is thought to be important for learning and memory, leading to alterations in sensory representations and cognitive maps. However, these changes must be coordinated across other synapses within local circuits to preserve neural coding schemes and the organization of excitatory and inhibitory inputs, i.e., excitatory-inhibitory balance. Recent studies indicate that inhibitory synapses are also plastic and are controlled directly by a large number of neuromodulators, particularly during episodes of learning. Many modulators transiently alter excitatory-inhibitory balance by decreasing inhibition, and thus disinhibition has emerged as a major mechanism by which neuromodulation might enable long-term synaptic modifications naturally. This review examines the relationships between neuromodulation and synaptic plasticity, focusing on the induction of long-term changes that collectively enhance cortical excitatory-inhibitory balance for improving perception and behavior. PMID:25897875

  1. Visuomotor transformations: early cortical mechanisms of reaching.

    PubMed

    Caminiti, R; Ferraina, S; Mayer, A B

    1998-12-01

    Recent studies of visually guided reaching in monkeys support the hypothesis that the visuomotor transformations underlying arm movements to spatial targets involve a parallel mechanism that simultaneously engages functionally related frontal and parietal areas linked by reciprocal cortico-cortical connections. The neurons in these areas possess similar combinations of response properties. The multimodal combinatorial properties of these neurons and the gradient architecture of the parietofrontal network emerge as a potential substrate to link the different sensory and motor signals that arise during reaching behavior into common hybrid reference frames. This convergent combinatorial process is evident at early stages of visual information processing in the occipito-parietal cortex, suggesting the existence of re-entrant motor influences on cortical areas once believed to have only visual functions. PMID:9914239

  2. Massive cortical reorganization in sighted Braille readers.

    PubMed

    Siuda-Krzywicka, Katarzyna; Bola, Łukasz; Paplińska, Małgorzata; Sumera, Ewa; Jednoróg, Katarzyna; Marchewka, Artur; Śliwińska, Magdalena W; Amedi, Amir; Szwed, Marcin

    2016-01-01

    The brain is capable of large-scale reorganization in blindness or after massive injury. Such reorganization crosses the division into separate sensory cortices (visual, somatosensory...). As its result, the visual cortex of the blind becomes active during tactile Braille reading. Although the possibility of such reorganization in the normal, adult brain has been raised, definitive evidence has been lacking. Here, we demonstrate such extensive reorganization in normal, sighted adults who learned Braille while their brain activity was investigated with fMRI and transcranial magnetic stimulation (TMS). Subjects showed enhanced activity for tactile reading in the visual cortex, including the visual word form area (VWFA) that was modulated by their Braille reading speed and strengthened resting-state connectivity between visual and somatosensory cortices. Moreover, TMS disruption of VWFA activity decreased their tactile reading accuracy. Our results indicate that large-scale reorganization is a viable mechanism recruited when learning complex skills. PMID:26976813

  3. Cortical Interneuron Subtypes Vary in Their Axonal Action Potential Properties

    PubMed Central

    Casale, Amanda E.; Foust, Amanda J.; Bal, Thierry

    2015-01-01

    The role of interneurons in cortical microcircuits is strongly influenced by their passive and active electrical properties. Although different types of interneurons exhibit unique electrophysiological properties recorded at the soma, it is not yet clear whether these differences are also manifested in other neuronal compartments. To address this question, we have used voltage-sensitive dye to image the propagation of action potentials into the fine collaterals of axons and dendrites in two of the largest cortical interneuron subtypes in the mouse: fast-spiking interneurons, which are typically basket or chandelier neurons; and somatostatin containing interneurons, which are typically regular spiking Martinotti cells. We found that fast-spiking and somatostatin-expressing interneurons differed in their electrophysiological characteristics along their entire dendrosomatoaxonal extent. The action potentials generated in the somata and axons, including axon collaterals, of somatostatin-expressing interneurons are significantly broader than those generated in the same compartments of fast-spiking inhibitory interneurons. In addition, action potentials back-propagated into the dendrites of somatostatin-expressing interneurons much more readily than fast-spiking interneurons. Pharmacological investigations suggested that axonal action potential repolarization in both cell types depends critically upon Kv1 channels, whereas the axonal and somatic action potentials of somatostatin-expressing interneurons also depend on BK Ca2+-activated K+ channels. These results indicate that the two broad classes of interneurons studied here have expressly different subcellular physiological properties, allowing them to perform unique computational roles in cortical circuit operations. SIGNIFICANCE STATEMENT Neurons in the cerebral cortex are of two major types: excitatory and inhibitory. The proper balance of excitation and inhibition in the brain is critical for its operation. Neurons

  4. Cortical necrosis in a renal transplant

    SciTech Connect

    Blumhardt, R.; Growcock, G.; Lasher, J.C.

    1983-07-01

    The /sup 99m/Tc-DTPA renogram is a well extabished noninvasive method for evaluating and following transplanted kidneys. The examination is useful in distinguishing rejection from acute tubular necrosis as well as demonstrating several less common complications such as vascular occlusion, urinary extravasation, obstruction, and lymphocele. A previously unreported condition involving a transplant kidney (i.e., renal cortical necrosis) is described which was diagnosed with renal scintigraphy in combination with sonography.

  5. Cortical subnetwork dynamics during human language tasks.

    PubMed

    Collard, Maxwell J; Fifer, Matthew S; Benz, Heather L; McMullen, David P; Wang, Yujing; Milsap, Griffin W; Korzeniewska, Anna; Crone, Nathan E

    2016-07-15

    Language tasks require the coordinated activation of multiple subnetworks-groups of related cortical interactions involved in specific components of task processing. Although electrocorticography (ECoG) has sufficient temporal and spatial resolution to capture the dynamics of event-related interactions between cortical sites, it is difficult to decompose these complex spatiotemporal patterns into functionally discrete subnetworks without explicit knowledge of each subnetwork's timing. We hypothesized that subnetworks corresponding to distinct components of task-related processing could be identified as groups of interactions with co-varying strengths. In this study, five subjects implanted with ECoG grids over language areas performed word repetition and picture naming. We estimated the interaction strength between each pair of electrodes during each task using a time-varying dynamic Bayesian network (tvDBN) model constructed from the power of high gamma (70-110Hz) activity, a surrogate for population firing rates. We then reduced the dimensionality of this model using principal component analysis (PCA) to identify groups of interactions with co-varying strengths, which we term functional network components (FNCs). This data-driven technique estimates both the weight of each interaction's contribution to a particular subnetwork, and the temporal profile of each subnetwork's activation during the task. We found FNCs with temporal and anatomical features consistent with articulatory preparation in both tasks, and with auditory and visual processing in the word repetition and picture naming tasks, respectively. These FNCs were highly consistent between subjects with similar electrode placement, and were robust enough to be characterized in single trials. Furthermore, the interaction patterns uncovered by FNC analysis correlated well with recent literature suggesting important functional-anatomical distinctions between processing external and self-produced speech. Our

  6. Preserved Coupling between the Reader's Voice and the Listener's Cortical Activity in Autism Spectrum Disorders

    PubMed Central

    Bourguignon, Mathieu; Wens, Vincent; Op de Beeck, Marc; Marty, Brice; Deconinck, Nicolas; Soncarrieu, Marie-Vincianne; Goldman, Serge; Jousmäki, Veikko; Van Bogaert, Patrick; De Tiège, Xavier

    2014-01-01

    Purpose Investigating the steadiness of the phase-coupling between the time-course of the reader's voice and brain signals of subjects with autism spectrum disorder (ASD) passively listening to connected speech using magnetoencephalography (MEG). In typically developed subjects, such coupling occurs at the right posterior temporal sulcus (pSTS) for frequencies below 1 Hz, and reflects the neural processing of sentence-level rhythmic prosody at the prelexical level. Methods Cortical neuromagnetic signals were recorded with MEG (Elekta Oy, Finland) while seven right-handed and native French-speaking ASD subjects (six males, one female, range: 13–20 years) listened to live (Live) or recorded (Recorded) voices continuously reading a text in French for five minutes. Coherence was computed between the reader's voice time-course and ASD subjects' MEG signals. Coherent neural sources were subsequently reconstructed using a beamformer. Key findings Significant coupling was found at 0.5 Hz in all ASD subjects in Live and in six subjects in Recorded. Coherent sources were located close to the right pSTS in both conditions. No significant difference was found in coherence levels between Live and Recorded, and between ASD subjects and ten typically developed subjects (right-handed, native French-speaking adults, 5 males, 5 females, age range: 21–38 years) included in a previous study. Significance This study discloses a preserved coupling between the reader's voice and ASD subjects' cortical activity at the right pSTS. These findings support the existence of preserved neural processing of sentence-level rhythmic prosody in ASD. The preservation of early cortical processing of prosodic elements in verbal language might be exploited in therapeutic interventions in ASD. PMID:24663673

  7. Brains swinging in concert: cortical phase synchronization while playing guitar

    PubMed Central

    Lindenberger, Ulman; Li, Shu-Chen; Gruber, Walter; Müller, Viktor

    2009-01-01

    Background Brains interact with the world through actions that are implemented by sensory and motor processes. A substantial part of these interactions consists in synchronized goal-directed actions involving two or more individuals. Hyperscanning techniques for assessing fMRI simultaneously from two individuals have been developed. However, EEG recordings that permit the assessment of synchronized neuronal activities at much higher levels of temporal resolution have not yet been simultaneously assessed in multiple individuals and analyzed in the time-frequency domain. In this study, we simultaneously recorded EEG from the brains of each of eight pairs of guitarists playing a short melody together to explore the extent and the functional significance of synchronized cortical activity in the course of interpersonally coordinated actions. Results By applying synchronization algorithms to intra- and interbrain analyses, we found that phase synchronization both within and between brains increased significantly during the periods of (i) preparatory metronome tempo setting and (ii) coordinated play onset. Phase alignment extracted from within-brain dynamics was related to behavioral play onset asynchrony between guitarists. Conclusion Our findings show that interpersonally coordinated actions are preceded and accompanied by between-brain oscillatory couplings. Presumably, these couplings reflect similarities in the temporal properties of the individuals' percepts and actions. Whether between-brain oscillatory couplings play a causal role in initiating and maintaining interpersonal action coordination needs to be clarified by further research. PMID:19292892

  8. Population interactions between parietal and primary motor cortices during reach

    PubMed Central

    Rao, Naveen G.; Bondy, Adrian; Truccolo, Wilson; Donoghue, John P.

    2014-01-01

    Neural interactions between parietal area 2/5 and primary motor cortex (M1) were examined to determine the timing and behavioral correlates of cortico-cortical interactions. Neural activity in areas 2/5 and M1 was simultaneously recorded with 96-channel microelectrode arrays in three rhesus monkeys performing a center-out reach task. We introduce a new method to reveal parietal-motor interactions at a population level using partial spike-field coherence (PSFC) between ensembles of neurons in one area and a local field potential (LFP) in another. PSFC reflects the extent of phase locking between spike times and LFP, after removing the coherence between LFPs in the two areas. Spectral analysis of M1 LFP revealed three bands: low, medium, and high, differing in power between movement preparation and performance. We focus on PSFC in the 1–10 Hz band, in which coherence was strongest. PSFC was also present in the 10–40 Hz band during movement preparation in many channels but generally nonsignificant in the 60–200 Hz band. Ensemble PSFC revealed stronger interactions than single cell-LFP pairings. PSFC of area 2/5 ensembles with M1 LFP typically rose around movement onset and peaked ∼500 ms afterward. PSFC was typically stronger for subsets of area 2/5 neurons and M1 LFPs with similar directional bias than for those with opposite bias, indicating that area 2/5 contributes movement direction information. Together with linear prediction of M1 LFP by area 2/5 spiking, the ensemble-LFP pairing approach reveals interactions missed by single neuron-LFP pairing, demonstrating that cortico-cortical communication can be more readily observed at the ensemble level. PMID:25210154

  9. Mechanisms of Firing Patterns in Fast-Spiking Cortical Interneurons

    PubMed Central

    Golomb, David; Donner, Karnit; Shacham, Liron; Shlosberg, Dan; Amitai, Yael; Hansel, David

    2007-01-01

    Cortical fast-spiking (FS) interneurons display highly variable electrophysiological properties. Their spike responses to step currents occur almost immediately following the step onset or after a substantial delay, during which subthreshold oscillations are frequently observed. Their firing patterns include high-frequency tonic firing and rhythmic or irregular bursting (stuttering). What is the origin of this variability? In the present paper, we hypothesize that it emerges naturally if one assumes a continuous distribution of properties in a small set of active channels. To test this hypothesis, we construct a minimal, single-compartment conductance-based model of FS cells that includes transient Na+, delayed-rectifier K+, and slowly inactivating d-type K+ conductances. The model is analyzed using nonlinear dynamical system theory. For small Na+ window current, the neuron exhibits high-frequency tonic firing. At current threshold, the spike response is almost instantaneous for small d-current conductance, gd, and it is delayed for larger gd. As gd further increases, the neuron stutters. Noise substantially reduces the delay duration and induces subthreshold oscillations. In contrast, when the Na+ window current is large, the neuron always fires tonically. Near threshold, the firing rates are low, and the delay to firing is only weakly sensitive to noise; subthreshold oscillations are not observed. We propose that the variability in the response of cortical FS neurons is a consequence of heterogeneities in their gd and in the strength of their Na+ window current. We predict the existence of two types of firing patterns in FS neurons, differing in the sensitivity of the delay duration to noise, in the minimal firing rate of the tonic discharge, and in the existence of subthreshold oscillations. We report experimental results from intracellular recordings supporting this prediction. PMID:17696606

  10. Familial Precocious Fetal Abnormal Cortical Sulcation.

    PubMed

    Frassoni, Carolina; Avagliano, Laura; Inverardi, Francesca; Spaccini, Luigina; Parazzini, Cecilia; Rustico, Maria Angela; Bulfamante, Gaetano; Righini, Andrea

    2016-08-01

    The development of the human cerebral cortex is a complex and precisely programmed process by which alterations may lead to morphological and functional neurological abnormalities. We report familial cases of prenatally diagnosed abnormal brain, characterized by aberrant symmetrical mesial oversulcation of the parietooccipital lobes, in fetuses affected by abnormal skeletal features. Fetal brain anomalies were characterized by prenatal magnetic resonance imaging at 21 weeks of gestation and histologically evaluated at 22 weeks. Histological examination added relevant information showing some focal cortical areas of micropoligyria and heterotopic extension of the cortical plate into the marginal zone beneath the cortical surface. Genetic analysis of the fetuses excluded FGFR3 mutations known to be related to skeletal dysplasia and aberrant symmetrical oversulcation in other brain areas (temporal lobes). Hence, the present report suggests the existence of a class of rare syndromes of skeleton and brain development abnormality unrelated to FGFR3 mutations or related to other not described FGFR3 gene defects. Using magnetic resonance imaging, histopathology and molecular characterization we provide an example of a translational study of a rare and unreported brain congenital malformation. PMID:27177044

  11. Coverage, continuity, and visual cortical architecture

    PubMed Central

    2011-01-01

    Background The primary visual cortex of many mammals contains a continuous representation of visual space, with a roughly repetitive aperiodic map of orientation preferences superimposed. It was recently found that orientation preference maps (OPMs) obey statistical laws which are apparently invariant among species widely separated in eutherian evolution. Here, we examine whether one of the most prominent models for the optimization of cortical maps, the elastic net (EN) model, can reproduce this common design. The EN model generates representations which optimally trade of stimulus space coverage and map continuity. While this model has been used in numerous studies, no analytical results about the precise layout of the predicted OPMs have been obtained so far. Results We present a mathematical approach to analytically calculate the cortical representations predicted by the EN model for the joint mapping of stimulus position and orientation. We find that in all the previously studied regimes, predicted OPM layouts are perfectly periodic. An unbiased search through the EN parameter space identifies a novel regime of aperiodic OPMs with pinwheel densities lower than found in experiments. In an extreme limit, aperiodic OPMs quantitatively resembling experimental observations emerge. Stabilization of these layouts results from strong nonlocal interactions rather than from a coverage-continuity-compromise. Conclusions Our results demonstrate that optimization models for stimulus representations dominated by nonlocal suppressive interactions are in principle capable of correctly predicting the common OPM design. They question that visual cortical feature representations can be explained by a coverage-continuity-compromise. PMID:22329968

  12. Computational modeling of epidural cortical stimulation

    NASA Astrophysics Data System (ADS)

    Wongsarnpigoon, Amorn; Grill, Warren M.

    2008-12-01

    Epidural cortical stimulation (ECS) is a developing therapy to treat neurological disorders. However, it is not clear how the cortical anatomy or the polarity and position of the electrode affects current flow and neural activation in the cortex. We developed a 3D computational model simulating ECS over the precentral gyrus. With the electrode placed directly above the gyrus, about half of the stimulus current flowed through the crown of the gyrus while current density was low along the banks deep in the sulci. Beneath the electrode, neurons oriented perpendicular to the cortical surface were depolarized by anodic stimulation, and neurons oriented parallel to the boundary were depolarized by cathodic stimulation. Activation was localized to the crown of the gyrus, and neurons on the banks deep in the sulci were not polarized. During regulated voltage stimulation, the magnitude of the activating function was inversely proportional to the thickness of the CSF and dura. During regulated current stimulation, the activating function was not sensitive to the thickness of the dura but was slightly more sensitive than during regulated voltage stimulation to the thickness of the CSF. Varying the width of the gyrus and the position of the electrode altered the distribution of the activating function due to changes in the orientation of the neurons beneath the electrode. Bipolar stimulation, although often used in clinical practice, reduced spatial selectivity as well as selectivity for neuron orientation.

  13. Changing interpretations of the human cortical pattern.

    PubMed

    Maudgil, D D

    1997-06-01

    There has been a long historical succession of scientific description of the cerebral cortex, usually accompanied by conflicting speculations on its function. It was noted by Thomas S. Kuhn that scientific descriptions are phrased in terms of the prevailing scientific paradigm and that disagreement about the interpretation of observed phenomena is what drives scientists to formulate new theories. The objectives of this study were to examine how the observation of Kuhn can help to gain insight into historical concepts of brain functioning from contemporary descriptions of the cortical gyrations, to examine how these historical concepts are relevant to neurology today, and to demonstrate how subjective these concepts are because they are based on interpretations that may be wrong. The method used here is examination of historical sources that give descriptions and illustrations of the cerebral cortex and contemporary theories of brain function. I have found that the emphases on cortical description have varied according to the prevailing contemporary paradigm. Debates about and between different paradigms mirror some themes in current neuroscience. In conclusion, the observations of Kuhn help to interpret descriptions to shed light on theories of cerebral cortical functioning, and they demonstrate that a scientific description is necessarily highly subjective (since it is phrased in terms of the current paradigm). The insights that can be gained are relevant to modern neurology and neuroscience research. PMID:9193213

  14. Cortical Reorganization following Injury Early in Life

    PubMed Central

    Artzi, Moran; Shiran, Shelly Irene; Weinstein, Maya; Myers, Vicki; Tarrasch, Ricardo; Schertz, Mitchell; Fattal-Valevski, Aviva; Miller, Elka; Gordon, Andrew M.; Green, Dido; Ben Bashat, Dafna

    2016-01-01

    The brain has a remarkable capacity for reorganization following injury, especially during the first years of life. Knowledge of structural reorganization and its consequences following perinatal injury is sparse. Here we studied changes in brain tissue volume, morphology, perfusion, and integrity in children with hemiplegia compared to typically developing children, using MRI. Children with hemiplegia demonstrated reduced total cerebral volume, with increased cerebrospinal fluid (CSF) and reduced total white matter volumes, with no differences in total gray matter volume, compared to typically developing children. An increase in cortical thickness at the hemisphere contralateral to the lesion (CLH) was detected in motor and language areas, which may reflect compensation for the gray matter loss in the lesion area or retention of ipsilateral pathways. In addition, reduced cortical thickness, perfusion, and surface area were detected in limbic areas. Increased CSF volume and precentral cortical thickness and reduced white matter volume were correlated with worse motor performance. Brain reorganization of the gray matter within the CLH, while not necessarily indicating better outcome, is suggested as a response to neuronal deficits following injury early in life. PMID:27298741

  15. Astrocytes refine cortical connectivity at dendritic spines

    PubMed Central

    Risher, W Christopher; Patel, Sagar; Kim, Il Hwan; Uezu, Akiyoshi; Bhagat, Srishti; Wilton, Daniel K; Pilaz, Louis-Jan; Singh Alvarado, Jonnathan; Calhan, Osman Y; Silver, Debra L; Stevens, Beth; Calakos, Nicole; Soderling, Scott H; Eroglu, Cagla

    2014-01-01

    During cortical synaptic development, thalamic axons must establish synaptic connections despite the presence of the more abundant intracortical projections. How thalamocortical synapses are formed and maintained in this competitive environment is unknown. Here, we show that astrocyte-secreted protein hevin is required for normal thalamocortical synaptic connectivity in the mouse cortex. Absence of hevin results in a profound, long-lasting reduction in thalamocortical synapses accompanied by a transient increase in intracortical excitatory connections. Three-dimensional reconstructions of cortical neurons from serial section electron microscopy (ssEM) revealed that, during early postnatal development, dendritic spines often receive multiple excitatory inputs. Immuno-EM and confocal analyses revealed that majority of the spines with multiple excitatory contacts (SMECs) receive simultaneous thalamic and cortical inputs. Proportion of SMECs diminishes as the brain develops, but SMECs remain abundant in Hevin-null mice. These findings reveal that, through secretion of hevin, astrocytes control an important developmental synaptic refinement process at dendritic spines. DOI: http://dx.doi.org/10.7554/eLife.04047.001 PMID:25517933

  16. Partial volume correction using cortical surfaces

    NASA Astrophysics Data System (ADS)

    Blaasvær, Kamille R.; Haubro, Camilla D.; Eskildsen, Simon F.; Borghammer, Per; Otzen, Daniel; Ostergaard, Lasse R.

    2010-03-01

    Partial volume effect (PVE) in positron emission tomography (PET) leads to inaccurate estimation of regional metabolic activities among neighbouring tissues with different tracer concentration. This may be one of the main limiting factors in the utilization of PET in clinical practice. Partial volume correction (PVC) methods have been widely studied to address this issue. MRI based PVC methods are well-established.1 Their performance depend on the quality of the co-registration of the MR and PET dataset, on the correctness of the estimated point-spread function (PSF) of the PET scanner and largely on the performance of the segmentation method that divide the brain into brain tissue compartments.1, 2 In the present study a method for PVC is suggested, that utilizes cortical surfaces, to obtain detailed anatomical information. The objectives are to improve the performance of PVC, facilitate a study of the relationship between metabolic activity in the cerebral cortex and cortical thicknesses, and to obtain an improved visualization of PET data. The gray matter metabolic activity after performing PVC was recovered by 99.7 - 99.8 % , in relation to the true activity when testing on simple simulated data with different PSFs and by 97.9 - 100 % when testing on simulated brain PET data at different cortical thicknesses. When studying the relationship between metabolic activities and anatomical structures it was shown on simulated brain PET data, that it is important to correct for PVE in order to get the true relationship.

  17. Visual stimuli recruit intrinsically generated cortical ensembles

    PubMed Central

    Miller, Jae-eun Kang; Ayzenshtat, Inbal; Carrillo-Reid, Luis; Yuste, Rafael

    2014-01-01

    The cortical microcircuit is built with recurrent excitatory connections, and it has long been suggested that the purpose of this design is to enable intrinsically driven reverberating activity. To understand the dynamics of neocortical intrinsic activity better, we performed two-photon calcium imaging of populations of neurons from the primary visual cortex of awake mice during visual stimulation and spontaneous activity. In both conditions, cortical activity is dominated by coactive groups of neurons, forming ensembles whose activation cannot be explained by the independent firing properties of their contributing neurons, considered in isolation. Moreover, individual neurons flexibly join multiple ensembles, vastly expanding the encoding potential of the circuit. Intriguingly, the same coactive ensembles can repeat spontaneously and in response to visual stimuli, indicating that stimulus-evoked responses arise from activating these intrinsic building blocks. Although the spatial properties of stimulus-driven and spontaneous ensembles are similar, spontaneous ensembles are active at random intervals, whereas visually evoked ensembles are time-locked to stimuli. We conclude that neuronal ensembles, built by the coactivation of flexible groups of neurons, are emergent functional units of cortical activity and propose that visual stimuli recruit intrinsically generated ensembles to represent visual attributes. PMID:25201983

  18. Cortical hot spots and labyrinths: why cortical neuromodulation for episodic migraine with aura should be personalized

    PubMed Central

    Dahlem, Markus A.; Schmidt, Bernd; Bojak, Ingo; Boie, Sebastian; Kneer, Frederike; Hadjikhani, Nouchine; Kurths, Jürgen

    2015-01-01

    Stimulation protocols for medical devices should be rationally designed. For episodic migraine with aura we outline model-based design strategies toward preventive and acute therapies using stereotactic cortical neuromodulation. To this end, we regard a localized spreading depression (SD) wave segment as a central element in migraine pathophysiology. To describe nucleation and propagation features of the SD wave segment, we define the new concepts of cortical hot spots and labyrinths, respectively. In particular, we firstly focus exclusively on curvature-induced dynamical properties by studying a generic reaction-diffusion model of SD on the folded cortical surface. This surface is described with increasing level of details, including finally personalized simulations using patient's magnetic resonance imaging (MRI) scanner readings. At this stage, the only relevant factor that can modulate nucleation and propagation paths is the Gaussian curvature, which has the advantage of being rather readily accessible by MRI. We conclude with discussing further anatomical factors, such as areal, laminar, and cellular heterogeneity, that in addition to and in relation to Gaussian curvature determine the generalized concept of cortical hot spots and labyrinths as target structures for neuromodulation. Our numerical simulations suggest that these target structures are like fingerprints, they are individual features of each migraine sufferer. The goal in the future will be to provide individualized neural tissue simulations. These simulations should predict the clinical data and therefore can also serve as a test bed for exploring stereotactic cortical neuromodulation. PMID:25798103

  19. Effect of age at onset on cortical thickness and cognition in posterior cortical atrophy.

    PubMed

    Suárez-González, Aida; Lehmann, Manja; Shakespeare, Timothy J; Yong, Keir X X; Paterson, Ross W; Slattery, Catherine F; Foulkes, Alexander J M; Rabinovici, Gil D; Gil-Néciga, Eulogio; Roldán-Lora, Florinda; Schott, Jonathan M; Fox, Nick C; Crutch, Sebastian J

    2016-08-01

    Age at onset (AAO) has been shown to influence the phenotype of Alzheimer's disease (AD), but how it affects atypical presentations of AD remains unknown. Posterior cortical atrophy (PCA) is the most common form of atypical AD. In this study, we aimed to investigate the effect of AAO on cortical thickness and cognitive function in 98 PCA patients. We used Freesurfer (v5.3.0) to compare cortical thickness with AAO both as a continuous variable, and by dichotomizing the groups based on median age (58 years). In both the continuous and dichotomized analyses, we found a pattern suggestive of thinner cortex in precuneus and parietal areas in earlier-onset PCA, and lower cortical thickness in anterior cingulate and prefrontal cortex in later-onset PCA. These cortical thickness differences between PCA subgroups were consistent with earlier-onset PCA patients performing worse on cognitive tests involving parietal functions. Our results provide a suggestion that AAO may not only affect the clinico-anatomical characteristics in AD but may also affect atrophy patterns and cognition within atypical AD phenotypes. PMID:27318138

  20. Effects of pregnancy on slow cortical potentials in migraine patients and healthy controls.

    PubMed

    Darabaneanu, S; Kropp, P; Niederberger, U; Strenge, H; Gerber, W-D

    2008-10-01

    Increased negative amplitudes and lack of habituation of contingent negative variation (CNV) in migraine are well established and are supposed to reflect an altered cortical excitability level. Migraine attacks occur less during pregnancy but often relapse after delivery. We investigated the effect of pregnancy on slow cortical potentials and reaction time in migraine patients and healthy controls. Four groups were examined: 14 pregnant migraine patients, 12 non-pregnant migraine patients, 15 pregnant healthy women and 16 non-pregnant healthy women aged 19-38 years. Two recordings were performed in the pregnant subjects: in the 36th week of gestation and 4 weeks after delivery. The non-pregnant subjects were recorded at the same time interval of 8 weeks. Pregnant migraine patients showed significantly fewer migraine days during the third trimester of pregnancy and returned to nearly the former level 4 weeks post delivery. Non-pregnant migraine patients demonstrated a significant reduction of migraine days at the second measurement. There was no effect of pregnancy on CNV amplitudes, but there was an effect of pregnancy on the habituation coefficient and reaction time of migraine patients. Faster habituation from a higher preactivation level was found. As an explanation for the changed habituation level we favour the model of correlation between preactivation level and habituation level, the so-called law of initial value. We found a correlation between preactivation level and habituation. Our study confirms a specific effect of pregnancy on slow cortical potentials in migraine patients. PMID:18624798

  1. Cortical membrane potential signature of optimal states for sensory signal detection

    PubMed Central

    McGinley, Matthew J.; David, Stephen V.; McCormick, David A.

    2015-01-01

    The neural correlates of optimal states for signal detection task performance are largely unknown. One hypothesis holds that optimal states exhibit tonically depolarized cortical neurons with enhanced spiking activity, such as occur during movement. We recorded membrane potentials of auditory cortical neurons in mice trained on a challenging tone-in-noise detection task while assessing arousal with simultaneous pupillometry and hippocampal recordings. Arousal measures accurately predicted multiple modes of membrane potential activity, including: rhythmic slow oscillations at low arousal, stable hyperpolarization at intermediate arousal, and depolarization during phasic or tonic periods of hyper-arousal. Walking always occurred during hyper-arousal. Optimal signal detection behavior and sound-evoked responses, at both sub-threshold and spiking levels, occurred at intermediate arousal when pre-decision membrane potentials were stably hyperpolarized. These results reveal a cortical physiological signature of the classically-observed inverted-U relationship between task performance and arousal, and that optimal detection exhibits enhanced sensory-evoked responses and reduced background synaptic activity. PMID:26074005

  2. Classification of motor imagery by means of cortical current density estimation and Von Neumann entropy.

    PubMed

    Kamousi, Baharan; Amini, Ali Nasiri; He, Bin

    2007-06-01

    The goal of the present study is to employ the source imaging methods such as cortical current density estimation for the classification of left- and right-hand motor imagery tasks, which may be used for brain-computer interface (BCI) applications. The scalp recorded EEG was first preprocessed by surface Laplacian filtering, time-frequency filtering, noise normalization and independent component analysis. Then the cortical imaging technique was used to solve the EEG inverse problem. Cortical current density distributions of left and right trials were classified from each other by exploiting the concept of Von Neumann entropy. The proposed method was tested on three human subjects (180 trials each) and a maximum accuracy of 91.5% and an average accuracy of 88% were obtained. The present results confirm the hypothesis that source analysis methods may improve accuracy for classification of motor imagery tasks. The present promising results using source analysis for classification of motor imagery enhances our ability of performing source analysis from single trial EEG data recorded on the scalp, and may have applications to improved BCI systems. PMID:17409476

  3. Dynamics and Organization of Cortical Microtubules as Revealed by Superresolution Structured Illumination Microscopy1[W

    PubMed Central

    Komis, George; Mistrik, Martin; Šamajová, Olga; Doskočilová, Anna; Ovečka, Miroslav; Illés, Peter; Bartek, Jiri; Šamaj, Jozef

    2014-01-01

    Plants employ acentrosomal mechanisms to organize cortical microtubule arrays essential for cell growth and differentiation. Using structured illumination microscopy (SIM) adopted for the optimal documentation of Arabidopsis (Arabidopsis thaliana) hypocotyl epidermal cells, dynamic cortical microtubules labeled with green fluorescent protein fused to the microtubule-binding domain of the mammalian microtubule-associated protein MAP4 and with green fluorescent protein-fused to the alpha tubulin6 were comparatively recorded in wild-type Arabidopsis plants and in the mitogen-activated protein kinase mutant mpk4 possessing the former microtubule marker. The mpk4 mutant exhibits extensive microtubule bundling, due to increased abundance and reduced phosphorylation of the microtubule-associated protein MAP65-1, thus providing a very useful genetic tool to record intrabundle microtubule dynamics at the subdiffraction level. SIM imaging revealed nano-sized defects in microtubule bundling, spatially resolved microtubule branching and release, and finally allowed the quantification of individual microtubules within cortical bundles. Time-lapse SIM imaging allowed the visualization of subdiffraction, short-lived excursions of the microtubule plus end, and dynamic instability behavior of both ends during free, intrabundle, or microtubule-templated microtubule growth and shrinkage. Finally, short, rigid, and nondynamic microtubule bundles in the mpk4 mutant were observed to glide along the parent microtubule in a tip-wise manner. In conclusion, this study demonstrates the potential of SIM for superresolution time-lapse imaging of plant cells, showing unprecedented details accompanying microtubule dynamic organization. PMID:24686112

  4. Selection of independent components based on cortical mapping of electromagnetic activity

    NASA Astrophysics Data System (ADS)

    Chan, Hui-Ling; Chen, Yong-Sheng; Chen, Li-Fen

    2012-10-01

    Independent component analysis (ICA) has been widely used to attenuate interference caused by noise components from the electromagnetic recordings of brain activity. However, the scalp topographies and associated temporal waveforms provided by ICA may be insufficient to distinguish functional components from artifactual ones. In this work, we proposed two component selection methods, both of which first estimate the cortical distribution of the brain activity for each component, and then determine the functional components based on the parcellation of brain activity mapped onto the cortical surface. Among all independent components, the first method can identify the dominant components, which have strong activity in the selected dominant brain regions, whereas the second method can identify those inter-regional associating components, which have similar component spectra between a pair of regions. For a targeted region, its component spectrum enumerates the amplitudes of its parceled brain activity across all components. The selected functional components can be remixed to reconstruct the focused electromagnetic signals for further analysis, such as source estimation. Moreover, the inter-regional associating components can be used to estimate the functional brain network. The accuracy of the cortical activation estimation was evaluated on the data from simulation studies, whereas the usefulness and feasibility of the component selection methods were demonstrated on the magnetoencephalography data recorded from a gender discrimination study.

  5. Cortical drive to breathe in amyotrophic lateral sclerosis: a dyspnoea-worsening defence?

    PubMed

    Georges, Marjolaine; Moraviec, Elise; Raux, Mathieu; Gonzalez-Bermejo, Jésus; Pradat, Pierre-François; Similowski, Thomas; Morélot-Panzini, Capucine

    2016-06-01

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease causing diaphragm weakness that can be partially compensated by inspiratory neck muscle recruitment. This disappears during sleep, which is compatible with a cortical contribution to the drive to breathe. We hypothesised that ALS patients with respiratory failure exhibit respiratory-related cortical activity, relieved by noninvasive ventilation (NIV) and related to dyspnoea.We studied 14 ALS patients with respiratory failure. Electroencephalographic recordings (EEGs) and electromyographic recordings of inspiratory neck muscles were performed during spontaneous breathing and NIV. Dyspnoea was evaluated using the Multidimensional Dyspnea Profile.Eight patients exhibited slow EEG negativities preceding inspiration (pre-inspiratory potentials) during spontaneous breathing. Pre-inspiratory potentials were attenuated during NIV (p=0.04). Patients without pre-inspiratory potentials presented more advanced forms of ALS and more severe respiratory impairment, but less severe dyspnoea. Patients with pre-inspiratory potentials had stronger inspiratory neck muscle activation and more severe dyspnoea during spontaneous breathing.ALS-related diaphragm weakness can engage cortical resources to augment the neural drive to breathe. This might reflect a compensatory mechanism, with the intensity of dyspnoea a negative consequence. Disease progression and the corresponding neural loss could abolish this phenomenon. A putative cognitive cost should be investigated. PMID:27076590

  6. Subthalamic stimulation modulates cortical motor network activity and synchronization in Parkinson’s disease

    PubMed Central

    Klotz, Rosa; Govindan, Rathinaswamy B.; Scholten, Marlieke; Naros, Georgios; Ramos-Murguialday, Ander; Bunjes, Friedemann; Meisner, Christoph; Plewnia, Christian; Krüger, Rejko

    2015-01-01

    Dynamic modulations of large-scale network activity and synchronization are inherent to a broad spectrum of cognitive processes and are disturbed in neuropsychiatric conditions including Parkinson’s disease. Here, we set out to address the motor network activity and synchronization in Parkinson’s disease and its modulation with subthalamic stimulation. To this end, 20 patients with idiopathic Parkinson’s disease with subthalamic nucleus stimulation were analysed on externally cued right hand finger movements with 1.5-s interstimulus interval. Simultaneous recordings were obtained from electromyography on antagonistic muscles (right flexor digitorum and extensor digitorum) together with 64-channel electroencephalography. Time-frequency event-related spectral perturbations were assessed to determine cortical and muscular activity. Next, cross-spectra in the time-frequency domain were analysed to explore the cortico-cortical synchronization. The time-frequency modulations enabled us to select a time-frequency range relevant for motor processing. On these time-frequency windows, we developed an extension of the phase synchronization index to quantify the global cortico-cortical synchronization and to obtain topographic differentiations of distinct electrode sites with respect to their contributions to the global phase synchronization index. The spectral measures were used to predict clinical and reaction time outcome using regression analysis. We found that movement-related desynchronization of cortical activity in the upper alpha and beta range was significantly facilitated with ‘stimulation on’ compared to ‘stimulation off’ on electrodes over the bilateral parietal, sensorimotor, premotor, supplementary-motor, and prefrontal areas, including the bilateral inferior prefrontal areas. These spectral modulations enabled us to predict both clinical and reaction time improvement from subthalamic stimulation. With ‘stimulation on’, interhemispheric cortico-cortical

  7. Electrical stimulation with a penetrating optic nerve electrode array elicits visuotopic cortical responses in cats

    NASA Astrophysics Data System (ADS)

    Lu, Yiliang; Yan, Yan; Chai, Xinyu; Ren, Qiushi; Chen, Yao; Li, Liming

    2013-06-01

    Objective. A visual prosthesis based on penetrating electrode stimulation within the optic nerve (ON) is a potential way to restore partial functional vision for blind patients. We investigated the retinotopic organization of ON stimulation and its spatial resolution. Approach. A five-electrode array was inserted perpendicularly into the ON or a single electrode was advanced to different depths within the ON (˜1-2 mm behind the eyeball, 13 cats). A sparse noise method was used to map ON electrode position and the visual cortex. Cortical responses were recorded by a 5 × 6 array. The visuotopic correspondence between the retinotopic position of the ON electrode was compared with the visual evoked cortical map and the electrical evoked potentials elicited in response to ON stimulation. Main results. Electrical stimulation with penetrating ON electrodes elicited cortical responses in visuotopographically corresponding areas of the cortex. Stimulation of the temporal side of the ON elicited cortical responses corresponding to the central visual field. The visual field position shifted from the lower to central visual field as the electrode penetrated through the depth of the ON. A spatial resolution of ˜ 2° to 3° within a limited cortical visuotopic representation could be obtained by this approach. Significance. Visuotopic electrical stimulation with a relatively fine spatial resolution can be accomplished using penetrating electrodes implanted at multiple sites and at different depths within the ON just behind the globe. This study also provides useful experimental data for the design of electrode density and the distribution of penetrating ON electrodes for a visual prosthesis.

  8. DEVELOPMENTAL APPEARANCE AND DISAPPEARANCE OF CORTICAL EVENTS AND OSCILLATIONS IN INFANT RATS

    PubMed Central

    Seelke, Adele M H; Blumberg, Mark S

    2010-01-01

    Until recently, organized and state-dependent neocortical activity in infant rats was thought to commence with the emergence of delta waves at postnatal day (P)11. This view is changing with the discovery of several forms of cortical activity that are detectible soon after birth, including spindle bursts (SBs) and slow activity transients (SATs). Here we provide further evidence of surprisingly rich cortical activity patterns during early development and document, in P5-P13 rats, the appearance, disappearance, and transient expression of three cortical events and oscillations. EEG activity in frontal, parietal, and occipital cortices was recorded in unanesthetized, head-fixed subjects using 16-channel laminar silicon electrodes and Ag-AgCl electrodes. In addition to SATs, we identified two novel forms of activity: cortical sharp potentials (CSPs) and gamma bursts (GBs). SBs were not observed in these areas. CSPs, defined as discrete, biphasic events with a duration of 250 ms, exhibited an inverted-U developmental trajectory with peak prevalence at P9. In contrast, GBs, defined as brief bursts of 40-Hz activity, increased steadily in prevalence and duration from P5 through P13. The prevalence of SATs decreased steadily across the ages tested here. Furthermore, both CSPs and GBs were more likely to occur during sleep than during wakefulness. Because SATs, CSPs, and GBs exhibit different developmental trajectories and rates of occurrence, and can occur independently of each other, they appear to be distinct patterns of neuronal activity. We hypothesize that these diverse patterns of neurophysiological activity reflect the instantaneous local structure and connectivity of the developing neocortex. PMID:20138849

  9. Developmental appearance and disappearance of cortical events and oscillations in infant rats.

    PubMed

    Seelke, Adele M H; Blumberg, Mark S

    2010-04-01

    Until recently, organized and state-dependent neocortical activity in infant rats was thought to commence with the emergence of delta waves at postnatal day (P)11. This view is changing with the discovery of several forms of cortical activity that are detectable soon after birth, including spindle bursts (SBs) and slow activity transients (SATs). Here we provide further evidence of surprisingly rich cortical activity patterns during early development and document, in P5-P13 rats, the appearance, disappearance, and transient expression of three cortical events and oscillations. EEG activity in frontal, parietal, and occipital cortices was recorded in unanesthetized, head-fixed subjects using 16-channel laminar silicon electrodes and Ag-AgCl electrodes. In addition to SATs, we identified two novel forms of activity: cortical sharp potentials (CSPs) and gamma bursts (GBs). SBs were not observed in these areas. CSPs, defined as discrete, biphasic events with a duration of 250 ms, exhibited an inverted-U developmental trajectory with peak prevalence at P9. In contrast, GBs, defined as brief bursts of 40-Hz activity, increased steadily in prevalence and duration from P5 through P13. The prevalence of SATs decreased steadily across the ages tested here. Furthermore, both CSPs and GBs were more likely to occur during sleep than during wakefulness. Because SATs, CSPs, and GBs exhibit different developmental trajectories and rates of occurrence, and can occur independently of each other, they appear to be distinct patterns of neuronal activity. We hypothesize that these diverse patterns of neurophysiological activity reflect the instantaneous local structure and connectivity of the developing neocortex. PMID:20138849

  10. Underarousal in Adult ADHD: How Are Peripheral and Cortical Arousal Related?

    PubMed

    Mayer, Kerstin; Wyckoff, Sarah Nicole; Strehl, Ute

    2016-07-01

    In children and adults with attention deficit/hyperactivity disorder (ADHD), a general slowing of spontaneous electroencephalographic (EEG) brain activity and a decrease of event-related potential amplitudes such as the contingent negative variation (CNV) are observed. Additionally, some studies have reported decreased skin conductance level (SCL) in this clinical population leading to the hypothesis of a peripheral hypoarousal, which may be a target of biofeedback treatment in addition to or instead of neurofeedback. To our knowledge, the relationship between SCL and CNV has not been simultaneously investigated in one experiment. Using the theoretical background of the hypoarousal model, this article aims to gain more insight into the differences and correlations of cortical (CNV) and peripheral (SCL) arousal in adults with ADHD. A sample of 23 adults with ADHD and 22 healthy controls underwent an auditory Go-NoGo task with simultaneous 22-channel EEG and SCL recordings. Reaction time (RT) and reaction time variability (RTV) were also measured to assess task performance. Significantly decreased CNV amplitude and significantly higher RTV were observed in the ADHD group, reflecting cortical underarousal and problems with sustained attention. No significant correlation between peripheral underarousal and cortical underarousal was observed in the ADHD group or the control group. The observed cortical underarousal reflected in the decreased CNV supports the notion of a reduced CNV amplitude as a possible biomarker for ADHD. However, the connection between cortical and peripheral arousal is not as clear as is suggested in previous research investigating both separately. Implications of these results for new treatment options for ADHD such as biofeedback are discussed. PMID:25802473

  11. Fluctuation Analysis of Centrosomes Reveals a Cortical Function of Kinesin-1.

    PubMed

    Winkler, Franziska; Gummalla, Maheshwar; Künneke, Lutz; Lv, Zhiyi; Zippelius, Annette; Aspelmeier, Timo; Grosshans, Jörg

    2015-09-01

    The actin and microtubule networks form the dynamic cytoskeleton. Network dynamics is driven by molecular motors applying force onto the networks and the interactions between the networks. Here we assay the dynamics of centrosomes in the scale of seconds as a proxy for the movement of microtubule asters. With this assay we want to detect the role of specific motors and of network interaction. During interphase of syncytial embryos of Drosophila, cortical actin and the microtubule network depend on each other. Centrosomes induce cortical actin to form caps, whereas F-actin anchors microtubules to the cortex. In addition, lateral interactions between microtubule asters are assumed to be important for regular spatial organization of the syncytial embryo. The functional interaction between the microtubule asters and cortical actin has been largely analyzed in a static manner, so far. We recorded the movement of centrosomes at 1 Hz and analyzed their fluctuations for two processes—pair separation and individual movement. We found that F-actin is required for directional movements during initial centrosome pair separation, because separation proceeds in a diffusive manner in latrunculin-injected embryos. For assaying individual movement, we established a fluctuation parameter as the deviation from temporally and spatially slowly varying drift movements. By analysis of mutant and drug-injected embryos, we found that the fluctuations were suppressed by both cortical actin and microtubules. Surprisingly, the microtubule motor Kinesin-1 also suppressed fluctuations to a similar degree as F-actin. Kinesin-1 may mediate linkage of the microtubule (+)-ends to the actin cortex. Consistent with this model is our finding that Kinesin-1-GFP accumulates at the cortical actin caps. PMID:26331244

  12. Delayed synchronization of activity in cortex and subthalamic nucleus following cortical stimulation in the rat

    PubMed Central

    Magill, Peter J; Sharott, Andrew; Bolam, J Paul; Brown, Peter

    2006-01-01

    Oscillations may play a role in the functional organization of cortico-basal ganglia-thalamocortical circuits, and it is important to understand their underlying mechanisms. The cortex often drives basal ganglia (BG) activity, and particularly, oscillatory activity in the subthalamic nucleus (STN). However, the STN may also indirectly influence cortex. The aim of this study was to characterize the delayed (>200 ms) responses of STN neurons to synchronized cortical inputs, focusing on their relationship with oscillatory cortical activity. We recorded the short-latency and delayed responses of STN units and frontal electrocorticogram (ECoG) to cortical stimulation in anaesthetized rats. Similar to previous studies, stimulation of ipsilateral frontal cortex, but not temporal cortex, evoked a short-latency triphasic response, followed by a sustained reduction or pause in firing, in rostral STN units. Caudal STN units did not show the short-latency triphasic response but often displayed a prolonged firing reduction. Oscillations in STN unit activity and ECoG were common after this sustained firing reduction, particularly between 200 and 600 ms after frontal cortical stimulation. These delayed oscillations were significantly coherent in a broad frequency band of 5–30 Hz. Coherence with ECoG at 5–15 Hz was observed throughout STN, though coherence at 15–30 Hz was largely restricted to rostral STN. Furthermore, oscillatory responses at 5–30 Hz in rostral STN predominantly led those in cortex (mean latency of 29 ms) after frontal cortical stimulation. These findings suggest that STN neurons responding to corticosubthalamic inputs may provide a delayed input to cortex, via BG output nuclei, and thence, thalamocortical pathways. PMID:16709634

  13. Self-organized criticality in cortical assemblies occurs in concurrent scale-free and small-world networks

    PubMed Central

    Massobrio, Paolo; Pasquale, Valentina; Martinoia, Sergio

    2015-01-01

    The spontaneous activity of cortical networks is characterized by the emergence of different dynamic states. Although several attempts were accomplished to understand the origin of these dynamics, the underlying factors continue to be elusive. In this work, we specifically investigated the interplay between network topology and spontaneous dynamics within the framework of self-organized criticality (SOC). The obtained results support the hypothesis that the emergence of critical states occurs in specific complex network topologies. By combining multi-electrode recordings of spontaneous activity of in vitro cortical assemblies with theoretical models, we demonstrate that different ‘connectivity rules’ drive the network towards different dynamic states. In particular, scale-free architectures with different degree of small-worldness account better for the variability observed in experimental data, giving rise to different dynamic states. Moreover, in relationship with the balance between excitation and inhibition and percentage of inhibitory hubs, the simulated cortical networks fall in a critical regime. PMID:26030608

  14. Cortical Thickness Abnormalities in Late Adolescence with Online Gaming Addiction

    PubMed Central

    Yuan, Kai; Cheng, Ping; Dong, Tao; Bi, Yanzhi; Xing, Lihong; Yu, Dahua; Zhao, Limei; Dong, Minghao; von Deneen, Karen M.; Liu, Yijun; Qin, Wei; Tian, Jie

    2013-01-01

    Online gaming addiction, as the most popular subtype of Internet addiction, had gained more and more attention from the whole world. However, the structural differences in cortical thickness of the brain between adolescents with online gaming addiction and healthy controls are not well unknown; neither was its association with the impaired cognitive control ability. High-resolution magnetic resonance imaging scans from late adolescence with online gaming addiction (n = 18) and age-, education- and gender-matched controls (n = 18) were acquired. The cortical thickness measurement method was employed to investigate alterations of cortical thickness in individuals with online gaming addiction. The color-word Stroop task was employed to investigate the functional implications of the cortical thickness abnormalities. Imaging data revealed increased cortical thickness in the left precentral cortex, precuneus, middle frontal cortex, inferior temporal and middle temporal cortices in late adolescence with online gaming addiction; meanwhile, the cortical thicknesses of the left lateral orbitofrontal cortex (OFC), insula, lingual gyrus, the right postcentral gyrus, entorhinal cortex and inferior parietal cortex were decreased. Correlation analysis demonstrated that the cortical thicknesses of the left precentral cortex, precuneus and lingual gyrus correlated with duration of online gaming addiction and the cortical thickness of the OFC correlated with the impaired task performance during the color-word Stroop task in adolescents with online gaming addiction. The findings in the current study suggested that the cortical thickness abnormalities of these regions may be implicated in the underlying pathophysiology of online gaming addiction. PMID:23326379

  15. Cortical thickness abnormalities in late adolescence with online gaming addiction.

    PubMed

    Yuan, Kai; Cheng, Ping; Dong, Tao; Bi, Yanzhi; Xing, Lihong; Yu, Dahua; Zhao, Limei; Dong, Minghao; von Deneen, Karen M; Liu, Yijun; Qin, Wei; Tian, Jie

    2013-01-01

    Online gaming addiction, as the most popular subtype of Internet addiction, had gained more and more attention from the whole world. However, the structural differences in cortical thickness of the brain between adolescents with online gaming addiction and healthy controls are not well unknown; neither was its association with the impaired cognitive control ability. High-resolution magnetic resonance imaging scans from late adolescence with online gaming addiction (n = 18) and age-, education- and gender-matched controls (n = 18) were acquired. The cortical thickness measurement method was employed to investigate alterations of cortical thickness in individuals with online gaming addiction. The color-word Stroop task was employed to investigate the functional implications of the cortical thickness abnormalities. Imaging data revealed increased cortical thickness in the left precentral cortex, precuneus, middle frontal cortex, inferior temporal and middle temporal cortices in late adolescence with online gaming addiction; meanwhile, the cortical thicknesses of the left lateral orbitofrontal cortex (OFC), insula, lingual gyrus, the right postcentral gyrus, entorhinal cortex and inferior parietal cortex were decreased. Correlation analysis demonstrated that the cortical thicknesses of the left precentral cortex, precuneus and lingual gyrus correlated with duration of online gaming addiction and the cortical thickness of the OFC correlated with the impaired task performance during the color-word Stroop task in adolescents with online gaming addiction. The findings in the current study suggested that the cortical thickness abnormalities of these regions may be implicated in the underlying pathophysiology of online gaming addiction. PMID:23326379

  16. Postmortem validation of MRI cortical volume measurements in MS.

    PubMed

    Popescu, Veronica; Klaver, Roel; Versteeg, Adriaan; Voorn, Pieter; Twisk, Jos W R; Barkhof, Frederik; Geurts, Jeroen J G; Vrenken, Hugo

    2016-06-01

    Grey matter (GM) atrophy is a prominent aspect of multiple sclerosis pathology and an important outcome in studies. GM atrophy measurement requires accurate GM segmentation. Several methods are used in vivo for measuring GM volumes in MS, but assessing their validity in vivo remains challenging. In this postmortem study, we evaluated the correlation between postmortem MRI cortical volume or thickness and the cortical thickness measured on histological sections. Sixteen MS brains were scanned in situ using 3DT1-weighted MRI and these images were used to measure regional cortical volume using FSL-SIENAX, FreeSurfer, and SPM, and regional cortical thickness using FreeSurfer. Subsequently, cortical thickness was measured histologically in 5 systematically sampled cortical areas. Linear regression analyses were used to evaluate the relation between MRI regional cortical volume or thickness and histological cortical thickness to determine which postprocessing technique was most valid. After correction for multiple comparisons, we observed a significant correlation with the histological cortical thickness for FSL-SIENAX cortical volume with manual editing (std. β = 0.345, adjusted R(2)  = 0.105, P = 0.005), and FreeSurfer cortical volume with manual editing (std. β = 0.379, adjusted R(2)  = 0.129, P = 0.003). In addition, there was a significant correlation between FreeSurfer cortical thickness with manual editing and histological cortical thickness (std. β = 0.381, adjusted R(2)  = 0.130, P = 0.003). The results support the use of FSL-SIENAX and FreeSurfer in cases of severe MS pathology. Interestingly none of the methods were significant in automated mode, which supports the use of manual editing to improve the automated segmentation. Hum Brain Mapp 37:2223-2233, 2016. © 2016 Wiley Periodicals, Inc. PMID:26945922

  17. Auditory experience-dependent cortical circuit shaping for memory formation in bird song learning

    PubMed Central

    Yanagihara, Shin; Yazaki-Sugiyama, Yoko

    2016-01-01

    As in human speech acquisition, songbird vocal learning depends on early auditory experience. During development, juvenile songbirds listen to and form auditory memories of adult tutor songs, which they use to shape their own vocalizations in later sensorimotor learning. The higher-level auditory cortex, called the caudomedial nidopallium (NCM), is a potential storage site for tutor song memory, but no direct electrophysiological evidence of tutor song memory has been found. Here, we identify the neuronal substrate for tutor song memory by recording single-neuron activity in the NCM of behaving juvenile zebra finches. After tutor song experience, a small subset of NCM neurons exhibit highly selective auditory responses to the tutor song. Moreover, blockade of GABAergic inhibition, and sleep decrease their selectivity. Taken together, these results suggest that experience-dependent recruitment of GABA-mediated inhibition shapes auditory cortical circuits, leading to sparse representation of tutor song memory in auditory cortical neurons. PMID:27327620

  18. Closed-loop cortical neuromodulation in Parkinson's disease: An alternative to deep brain stimulation?

    PubMed

    Beuter, Anne; Lefaucheur, Jean-Pascal; Modolo, Julien

    2014-05-01

    Deep brain stimulation (DBS) is usually performed to treat advanced Parkinson's disease (PD) patients with electrodes permanently implanted in basal ganglia while the stimulator delivers electrical impulses continuously and independently of any feedback (open-loop stimulation). Conversely, in closed-loop stimulation, electrical stimulation is delivered as a function of neuronal activities recorded and analyzed online. There is an emerging development of closed-loop DBS in the treatment of PD and a growing discussion about proposing cortical stimulation rather than DBS for this purpose. Why does it make sense to "close the loop" to treat parkinsonian symptoms? Could closed-loop stimulation applied to the cortex become a valuable therapeutic strategy for PD? Can mathematical modeling contribute to the development of this technique? We review the various evidences in favor of the use of closed-loop cortical stimulation for the treatment of advanced PD, as an emerging technique which might offer substantial clinical benefits for PD patients. PMID:24555921

  19. A common structure underlies low-frequency cortical dynamics in movement, sleep, and sedation.

    PubMed

    Hall, Thomas M; de Carvalho, Felipe; Jackson, Andrew

    2014-09-01

    Upper-limb movements are often composed of regular submovements, and neural correlates of submovement frequencies between 1 and 4 Hz have been found in the motor cortex. The temporal profile of movements is usually assumed to be determined by extrinsic factors such as limb biomechanics and feedback delays, but another possibility is that an intrinsic rhythmicity contributes to low frequencies in behavior. We used multielectrode recordings in monkeys performing an isometric movement task to reveal cyclic activity in primary motor cortex locked to submovements, and a distinct oscillation in premotor cortex. During ketamine sedation and natural sleep, cortical activity traversed similar cycles and became synchronized across areas. Because the same cortical dynamics are coupled to submovements and also observed in the absence of behavior, we conclude that the motor networks controlling the upper limb exhibit an intrinsic periodicity at submovement frequencies that is reflected in the speed profile of movements. PMID:25132467

  20. Do Male And Female Cyclists' Cortical Activity Differ Before and During Cycling Exercise?

    PubMed

    Ludyga, Sebastian; Gronwald, Thomas; Hottenrott, Kuno

    2015-12-01

    Although men and women are suggested to vary in resistance to fatigue, possible sex difference in its central component have rarely been investigated via electroencephalography (EEG). Therefore, we examined differences in cortical activity between male and female cyclists (n = 26) during cycling exercise. Participants performed an incremental test to derive the anaerobic threshold from the lactate power curve. In addition, cyclists' cortical activity was recorded with EEG before and during cycling exercise. Whereas women showed higher frontal alpha and beta activity at rest, no sex-specific differences of relative EEG spectral power occurred during cycling at higher intensity. Women and men's brains respond similarly during submaximal cycling, as both sexes show an inverted U-shaped curve of alpha power. Therefore, sex differences observable at rest vanish after the onset of exercise. PMID:26866769

  1. The influence of lexical statistics on temporal lobe cortical dynamics during spoken word listening

    PubMed Central

    Cibelli, Emily S.; Leonard, Matthew K.; Johnson, Keith; Chang, Edward F.

    2015-01-01

    Neural representations of words are thought to have a complex spatio-temporal cortical basis. It has been suggested that spoken word recognition is not a process of feed-forward computations from phonetic to lexical forms, but rather involves the online integration of bottom-up input with stored lexical knowledge. Using direct neural recordings from the temporal lobe, we examined cortical responses to words and pseudowords. We found that neural populations were not only sensitive to lexical status (real vs. pseudo), but also to cohort size (number of words matching the phonetic input at each time point) and cohort frequency (lexical frequency of those words). These lexical variables modulated neural activity from the posterior to anterior temporal lobe, and also dynamically as the stimuli unfolded on a millisecond time scale. Our findings indicate that word recognition is not purely modular, but relies on rapid and online integration of multiple sources of lexical knowledge. PMID:26072003

  2. The influence of lexical statistics on temporal lobe cortical dynamics during spoken word listening.

    PubMed

    Cibelli, Emily S; Leonard, Matthew K; Johnson, Keith; Chang, Edward F

    2015-08-01

    Neural representations of words are thought to have a complex spatio-temporal cortical basis. It has been suggested that spoken word recognition is not a process of feed-forward computations from phonetic to lexical forms, but rather involves the online integration of bottom-up input with stored lexical knowledge. Using direct neural recordings from the temporal lobe, we examined cortical responses to words and pseudowords. We found that neural populations were not only sensitive to lexical status (real vs. pseudo), but also to cohort size (number of words matching the phonetic input at each time point) and cohort frequency (lexical frequency of those words). These lexical variables modulated neural activity from the posterior to anterior temporal lobe, and also dynamically as the stimuli unfolded on a millisecond time scale. Our findings indicate that word recognition is not purely modular, but relies on rapid and online integration of multiple sources of lexical knowledge. PMID:26072003

  3. Arousal and locomotion make distinct contributions to cortical activity patterns and visual encoding.

    PubMed

    Vinck, Martin; Batista-Brito, Renata; Knoblich, Ulf; Cardin, Jessica A

    2015-05-01

    Spontaneous and sensory-evoked cortical activity is highly state-dependent, yet relatively little is known about transitions between distinct waking states. Patterns of activity in mouse V1 differ dramatically between quiescence and locomotion, but this difference could be explained by either motor feedback or a change in arousal levels. We recorded single cells and local field potentials from area V1 in mice head-fixed on a running wheel and monitored pupil diameter to assay arousal. Using naturally occurring and induced state transitions, we dissociated arousal and locomotion effects in V1. Arousal suppressed spontaneous firing and strongly altered the temporal patterning of population activity. Moreover, heightened arousal increased the signal-to-noise ratio of visual responses and reduced noise correlations. In contrast, increased firing in anticipation of and during movement was attributable to locomotion effects. Our findings suggest complementary roles of arousal and locomotion in promoting functional flexibility in cortical circuits. PMID:25892300

  4. Extracting Kinematic Parameters for Monkey Bipedal Walking from Cortical Neuronal Ensemble Activity

    PubMed Central

    Fitzsimmons, Nathan A.; Lebedev, Mikhail A.; Peikon, Ian D.; Nicolelis, Miguel A. L.

    2009-01-01

    The ability to walk may be critically impacted as the result of neurological injury or disease. While recent advances in brain–machine interfaces (BMIs) have demonstrated the feasibility of upper-limb neuroprostheses, BMIs have not been evaluated as a means to restore walking. Here, we demonstrate that chronic recordings from ensembles of cortical neurons can be used to predict the kinematics of bipedal walking in rhesus macaques – both offline and in real time. Linear decoders extracted 3D coordinates of leg joints and leg muscle electromyograms from the activity of hundreds of cortical neurons. As more complex patterns of walking were produced by varying the gait speed and direction, larger neuronal populations were needed to accurately extract walking patterns. Extraction was further improved using a switching decoder which designated a submodel for each walking paradigm. We propose that BMIs may one day allow severely paralyzed patients to walk again. PMID:19404411

  5. Cortical potentials in an auditory oddball task reflect individual differences in working memory capacity

    PubMed Central

    Yurgil, Kate A.; Golob, Edward J.

    2014-01-01

    This study determined whether auditory cortical responses associated with mechanisms of attention vary with individual differences in working memory capacity (WMC) and perceptual load. The operation span test defined subjects with low vs. high WMC, who then discriminated target/nontarget tones while EEG was recorded. Infrequent white noise distracters were presented at midline or ±90° locations, and perceptual load was manipulated by varying nontarget frequency. Amplitude of the N100 to distracters was negatively correlated with WMC. Relative to targets, only high WMC subjects showed attenuated N100 amplitudes to nontargets. In the higher WMC group, increased perceptual load was associated with decreased P3a amplitudes to distracters and longer-lasting negative slow wave to nontargets. Results show that auditory cortical processing is associated with multiple facets of attention control related to WMC and possibly higher-level cognition. PMID:24016201

  6. Auditory experience-dependent cortical circuit shaping for memory formation in bird song learning.

    PubMed

    Yanagihara, Shin; Yazaki-Sugiyama, Yoko

    2016-01-01

    As in human speech acquisition, songbird vocal learning depends on early auditory experience. During development, juvenile songbirds listen to and form auditory memories of adult tutor songs, which they use to shape their own vocalizations in later sensorimotor learning. The higher-level auditory cortex, called the caudomedial nidopallium (NCM), is a potential storage site for tutor song memory, but no direct electrophysiological evidence of tutor song memory has been found. Here, we identify the neuronal substrate for tutor song memory by recording single-neuron activity in the NCM of behaving juvenile zebra finches. After tutor song experience, a small subset of NCM neurons exhibit highly selective auditory responses to the tutor song. Moreover, blockade of GABAergic inhibition, and sleep decrease their selectivity. Taken together, these results suggest that experience-dependent recruitment of GABA-mediated inhibition shapes auditory cortical circuits, leading to sparse representation of tutor song memory in auditory cortical neurons. PMID:27327620

  7. Seizures induced by direct electrical cortical stimulation--Mechanisms and clinical considerations.

    PubMed

    Kovac, Stjepana; Kahane, Philippe; Diehl, Beate

    2016-01-01

    Direct electrical cortical stimulation (CS) is widely used to map eloquent cortex. It can be applied extraoperatively in patients undergoing intracranial EEG recordings using chronically implanted electrodes (subdural, depth or a combination), or it can be used intraoperatively. Seizures can be induced by CS but there is controversy regarding the utility of CS induced seizures in defining the epileptogenic zone and hence practice varies considerably between centres. Some centres use seizures induced by direct CS routinely to aid in defining the epileptogenic zone. In contrast, others do not rely on such information and explicitly avoid stimulating seizures during cortical mapping. Intra- and extraoperative techniques have been used to stimulate seizures with varying results, which may in part reflect these methodological differences. We here aim to review current views, definitions and studies on seizures induced by direct electrical CS. In addition we discuss mechanisms and methodological considerations of this procedure. PMID:25613034

  8. Rate and timing of cortical responses driven by separate sensory channels

    PubMed Central

    Saal, Hannes P; Harvey, Michael A; Bensmaia, Sliman J

    2015-01-01

    The sense of touch comprises multiple sensory channels that each conveys characteristic signals during interactions with objects. These neural signals must then be integrated in such a way that behaviorally relevant information about the objects is preserved. To understand the process of integration, we implement a simple computational model that describes how the responses of neurons in somatosensory cortex—recorded from awake, behaving monkeys—are shaped by the peripheral input, reconstructed using simulations of neuronal populations that reproduce natural spiking responses in the nerve with millisecond precision. First, we find that the strength of cortical responses is driven by one population of nerve fibers (rapidly adapting) whereas the timing of cortical responses is shaped by the other (Pacinian). Second, we show that input from these sensory channels is integrated in an optimal fashion that exploits the disparate response behaviors of different fiber types. DOI: http://dx.doi.org/10.7554/eLife.10450.001 PMID:26650354

  9. More sensitivity of cortical GABAergic neurons than glutamatergic neurons in response to acidosis.

    PubMed

    Liu, Hua; Li, Fang; Wang, Chunyan; Su, Zhiqiang

    2016-05-25

    Acidosis impairs brain functions. Neuron-specific mechanisms underlying acidosis-induced brain dysfunction remain elusive. We studied the sensitivity of cortical GABAergic neurons and glutamatergic neurons to acidosis by whole-cell recording in brain slices. The acidification to the neurons was induced by perfusing artificial cerebral spinal fluid with lower pH. This acidification impairs excitability and synaptic transmission in the glutamatergic and GABAergic neurons. Acidosis impairs spiking capacity in the GABAergic neurons more than in the glutamatergic neurons. Acidosis also strengthens glutamatergic synaptic transmission and attenuates GABAergic synaptic transmission on the GABAergic neurons more than the glutamatergic neurons, which results in the functional impairment of these GABAergic neurons. This acidosis-induced dysfunction predominantly in the cortical GABAergic neurons drives the homeostasis of neuronal networks toward overexcitation and exacerbates neuronal impairment. PMID:27116702

  10. Hierarchical Interaction Structure of Neural Activities in Cortical Slice Cultures

    PubMed Central

    Santos, Gustavo S.; Gireesh, Elakkat D.; Plenz, Dietmar; Nakahara, Hiroyuki

    2010-01-01

    Recent advances in the analysis of neuronal activities suggest that the instantaneous activity patterns can be mostly explained by considering only first-order and pairwise interactions between recorded elements, i.e., action potentials or local field potentials (LFP), and do not require higher-than-pairwise-order interactions. If generally applicable, this pairwise approach greatly simplifies the description of network interactions. However, an important question remains: are the recorded elements the units of interaction that best describe neuronal activity patterns? To explore this, we recorded spontaneous LFP peak activities in cortical organotypic cultures using planar, integrated 60-microelectrode arrays. We compared predictions obtained using a pairwise approach with those using a hierarchical approach that uses two different spatial units for describing the activity interactions: single electrodes and electrode clusters. In this hierarchical model, short-range interactions within each cluster were modeled by pairwise interactions of electrode activities and long-range interactions were modeled by pairwise interactions of cluster activities. Despite the relatively low number of parameters used, the hierarchical model provided a more accurate description of the activity patterns than the pairwise model when applied to ensembles of 10 electrodes. Furthermore, the hierarchical model was successfully applied to a larger-scale data of ~60 electrodes. Electrode activities within clusters were highly correlated and spatially contiguous. In contrast, long-range interactions were diffuse, suggesting the presence of higher-than-pairwise-order interactions involved in the LFP peak activities. Thus, the identification of appropriate units of interaction may allow for the successful characterization of neuronal activities in large-scale networks. PMID:20592194

  11. Cortical Spectral Activity and Connectivity during Active and Viewed Arm and Leg Movement

    PubMed Central

    Kline, Julia E.; Huang, Helen J.; Snyder, Kristine L.; Ferris, Daniel P.

    2016-01-01

    Active and viewed limb movement activate many similar neural pathways, however, to date most comparison studies have focused on subjects making small, discrete movements of the hands and feet. The purpose of this study was to determine if high-density electroencephalography (EEG) could detect differences in cortical activity and connectivity during active and viewed rhythmic arm and leg movements in humans. Our primary hypothesis was that we would detect similar but weaker electrocortical spectral fluctuations and effective connectivity fluctuations during viewed limb exercise compared to active limb exercise due to the similarities in neural recruitment. A secondary hypothesis was that we would record stronger cortical spectral fluctuations for arm exercise compared to leg exercise, because rhythmic arm exercise would be more dependent on supraspinal control than rhythmic leg exercise. We recorded EEG data while ten young healthy subjects exercised on a recumbent stepper with: (1) both arms and legs, (2) just legs, and (3) just arms. Subjects also viewed video playback of themselves or another individual performing the same exercises. We performed independent component analysis, dipole fitting, spectral analysis, and effective connectivity analysis on the data. Cortical areas comprising the premotor and supplementary motor cortex, the anterior cingulate, the posterior cingulate, and the parietal cortex exhibited significant spectral fluctuations during rhythmic limb exercise. These fluctuations tended to be greater for the arms exercise conditions than for the legs only exercise condition, which suggests that human rhythmic arm movements are under stronger cortical control than rhythmic leg movements. We did not find consistent spectral fluctuations in these areas during the viewed conditions, but effective connectivity fluctuated at harmonics of the exercise frequency during both active and viewed rhythmic limb exercise. The right premotor and supplementary motor

  12. Critical Fluctuations in Cortical Models Near Instability

    PubMed Central

    Aburn, Matthew J.; Holmes, C. A.; Roberts, James A.; Boonstra, Tjeerd W.; Breakspear, Michael

    2012-01-01

    Computational studies often proceed from the premise that cortical dynamics operate in a linearly stable domain, where fluctuations dissipate quickly and show only short memory. Studies of human electroencephalography (EEG), however, have shown significant autocorrelation at time lags on the scale of minutes, indicating the need to consider regimes where non-linearities influence the dynamics. Statistical properties such as increased autocorrelation length, increased variance, power law scaling, and bistable switching have been suggested as generic indicators of the approach to bifurcation in non-linear dynamical systems. We study temporal fluctuations in a widely-employed computational model (the Jansen–Rit model) of cortical activity, examining the statistical signatures that accompany bifurcations. Approaching supercritical Hopf bifurcations through tuning of the background excitatory input, we find a dramatic increase in the autocorrelation length that depends sensitively on the direction in phase space of the input fluctuations and hence on which neuronal subpopulation is stochastically perturbed. Similar dependence on the input direction is found in the distribution of fluctuation size and duration, which show power law scaling that extends over four orders of magnitude at the Hopf bifurcation. We conjecture that the alignment in phase space between the input noise vector and the center manifold of the Hopf bifurcation is directly linked to these changes. These results are consistent with the possibility of statistical indicators of linear instability being detectable in real EEG time series. However, even in a simple cortical model, we find that these indicators may not necessarily be visible even when bifurcations are present because their expression can depend sensitively on the neuronal pathway of incoming fluctuations. PMID:22952464

  13. Discontinuity of cortical gradients reflects sensory impairment.

    PubMed

    Saadon-Grosman, Noam; Tal, Zohar; Itshayek, Eyal; Amedi, Amir; Arzy, Shahar

    2015-12-29

    Topographic maps and their continuity constitute a fundamental principle of brain organization. In the somatosensory system, whole-body sensory impairment may be reflected either in cortical signal reduction or disorganization of the somatotopic map, such as disturbed continuity. Here we investigated the role of continuity in pathological states. We studied whole-body cortical representations in response to continuous sensory stimulation under functional MRI (fMRI) in two unique patient populations-patients with cervical sensory Brown-Séquard syndrome (injury to one side of the spinal cord) and patients before and after surgical repair of cervical disk protrusion-enabling us to compare whole-body representations in the same study subjects. We quantified the spatial gradient of cortical activation and evaluated the divergence from a continuous pattern. Gradient continuity was found to be disturbed at the primary somatosensory cortex (S1) and the supplementary motor area (SMA), in both patient populations: contralateral to the disturbed body side in the Brown-Séquard group and before repair in the surgical group, which was further improved after intervention. Results corresponding to the nondisturbed body side and after surgical repair were comparable with control subjects. No difference was found in the fMRI signal power between the different conditions in the two groups, as well as with respect to control subjects. These results suggest that decreased sensation in our patients is related to gradient discontinuity rather than signal reduction. Gradient continuity may be crucial for somatotopic and other topographical organization, and its disruption may characterize pathological processing. PMID:26655739

  14. Discontinuity of cortical gradients reflects sensory impairment

    PubMed Central

    Saadon-Grosman, Noam; Tal, Zohar; Itshayek, Eyal; Amedi, Amir; Arzy, Shahar

    2015-01-01

    Topographic maps and their continuity constitute a fundamental principle of brain organization. In the somatosensory system, whole-body sensory impairment may be reflected either in cortical signal reduction or disorganization of the somatotopic map, such as disturbed continuity. Here we investigated the role of continuity in pathological states. We studied whole-body cortical representations in response to continuous sensory stimulation under functional MRI (fMRI) in two unique patient populations—patients with cervical sensory Brown-Séquard syndrome (injury to one side of the spinal cord) and patients before and after surgical repair of cervical disk protrusion—enabling us to compare whole-body representations in the same study subjects. We quantified the spatial gradient of cortical activation and evaluated the divergence from a continuous pattern. Gradient continuity was found to be disturbed at the primary somatosensory cortex (S1) and the supplementary motor area (SMA), in both patient populations: contralateral to the disturbed body side in the Brown-Séquard group and before repair in the surgical group, which was further improved after intervention. Results corresponding to the nondisturbed body side and after surgical repair were comparable with control subjects. No difference was found in the fMRI signal power between the different conditions in the two groups, as well as with respect to control subjects. These results suggest that decreased sensation in our patients is related to gradient discontinuity rather than signal reduction. Gradient continuity may be crucial for somatotopic and other topographical organization, and its disruption may characterize pathological processing. PMID:26655739

  15. Automatic cortical thickness analysis on rodent brain

    NASA Astrophysics Data System (ADS)

    Lee, Joohwi; Ehlers, Cindy; Crews, Fulton; Niethammer, Marc; Budin, Francois; Paniagua, Beatriz; Sulik, Kathy; Johns, Josephine; Styner, Martin; Oguz, Ipek

    2011-03-01

    Localized difference in the cortex is one of the most useful morphometric traits in human and animal brain studies. There are many tools and methods already developed to automatically measure and analyze cortical thickness for the human brain. However, these tools cannot be directly applied to rodent brains due to the different scales; even adult rodent brains are 50 to 100 times smaller than humans. This paper describes an algorithm for automatically measuring the cortical thickness of mouse and rat brains. The algorithm consists of three steps: segmentation, thickness measurement, and statistical analysis among experimental groups. The segmentation step provides the neocortex separation from other brain structures and thus is a preprocessing step for the thickness measurement. In the thickness measurement step, the thickness is computed by solving a Laplacian PDE and a transport equation. The Laplacian PDE first creates streamlines as an analogy of cortical columns; the transport equation computes the length of the streamlines. The result is stored as a thickness map over the neocortex surface. For the statistical analysis, it is important to sample thickness at corresponding points. This is achieved by the particle correspondence algorithm which minimizes entropy between dynamically moving sample points called particles. Since the computational cost of the correspondence algorithm may limit the number of corresponding points, we use thin-plate spline based interpolation to increase the number of corresponding sample points. As a driving application, we measured the thickness difference to assess the effects of adolescent intermittent ethanol exposure that persist into adulthood and performed t-test between the control and exposed rat groups. We found significantly differing regions in both hemispheres.

  16. Regional vulnerability of longitudinal cortical association connectivity

    PubMed Central

    Ceschin, Rafael; Lee, Vince K.; Schmithorst, Vince; Panigrahy, Ashok

    2015-01-01

    Preterm born children with spastic diplegia type of cerebral palsy and white matter injury or periventricular leukomalacia (PVL), are known to have motor, visual and cognitive impairments. Most diffusion tensor imaging (DTI) studies performed in this group have demonstrated widespread abnormalities using averaged deterministic tractography and voxel-based DTI measurements. Little is known about structural network correlates of white matter topography and reorganization in preterm cerebral palsy, despite the availability of new therapies and the need for brain imaging biomarkers. Here, we combined novel post-processing methodology of probabilistic tractography data in this preterm cohort to improve spatial and regional delineation of longitudinal cortical association tract abnormalities using an along-tract approach, and compared these data to structural DTI cortical network topology analysis. DTI images were acquired on 16 preterm children with cerebral palsy (mean age 5.6 ± 4) and 75 healthy controls (mean age 5.7 ± 3.4). Despite mean tract analysis, Tract-Based Spatial Statistics (TBSS) and voxel-based morphometry (VBM) demonstrating diffusely reduced fractional anisotropy (FA) reduction in all white matter tracts, the along-tract analysis improved the detection of regional tract vulnerability. The along-tract map-structural network topology correlates revealed two associations: (1) reduced regional posterior–anterior gradient in FA of the longitudinal visual cortical association tracts (inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, optic radiation, posterior thalamic radiation) correlated with reduced posterior–anterior gradient of intra-regional (nodal efficiency) metrics with relative sparing of frontal and temporal regions; and (2) reduced regional FA within frontal–thalamic–striatal white matter pathways (anterior limb/anterior thalamic radiation, superior longitudinal fasciculus and cortical spinal tract) correlated

  17. Cortical blindness in acute carbon monoxide poisoning.

    PubMed

    Katafuchi, Y; Nishimi, T; Yamaguchi, Y; Matsuishi, T; Kimura, Y; Otaki, E; Yamashita, Y

    1985-01-01

    A 3-year-old boy had persistent cortical blindness following acute carbon monoxide poisoning. He was believed to have suffered anoxic brain damage due to incomplete combustion of the briquette-type solid fuel. Computed tomographic (CT) scan of the brain and visual evoked potentials (VEP) in the early stage were normal. However, on the 20th hospital day CT scan showed leukomalacia and VEP showed an absence of N1-, and P1-waves which was well correlated with the clinical feature at that time. PMID:4083389

  18. Dynamic functional tuning of nonlinear cortical networks

    NASA Astrophysics Data System (ADS)

    Stetter, Martin

    2006-03-01

    The mammalian neocortex is a highly complex and nonlinear dynamic system. One of its most prominent features is an omnipresent spontaneous neuronal activity. Here the possible functional role of this global background for cognitive flexibility is studied in a prototypic mean-field model area. It is demonstrated that the level of global background current efficiently controls the stimulus-response threshold and the stability and properties of short-term memory states. Moreover, it can dynamically gate arbitrary cortical subnetworks, when applied to parts of the area as a weak bias signal. These results suggest a central functional role of the level of background activation: the dynamic functional tuning of neocortical circuits.

  19. Evidence of cortical reorganization in hemiparetic patients

    SciTech Connect

    Brion, J.P.; Demeurisse, G.; Capon, A. )

    1989-08-01

    We studied the mechanisms underlying the recovery of motor function of the hand using a bidimensional xenon-133 inhalation technique to measure regional cerebral blood flow at rest and during the performance of a motor task (test condition). The regional cerebral blood flow patterns under rest and test conditions were compared in normal control and in stroke patients with either a cortico-subcortical or a deep-seated lesion. Functional recovery appears to depend upon cortical reorganization involving both hemispheres, particularly in both parietal regions in the subgroup of patients with cortico-subcortical lesions.

  20. Iatrogenic cortical aneurysm post-craniotomy.

    PubMed

    Zanini, Marco Antonio; Borges, Rodrigo Almeida; Nunes Aquino, Gustavo Henrique; de Freitas, Carlos Clayton Macedo

    2010-04-01

    Taking into account the number of craniotomies performed every day around the world, iatrogenic aneurysm post-craniotomy is extremely rare with only anecdotal cases reported in literature. We report an iatrogenic aneurysm affecting a cortical vessel which probably developed during dural closure of a conventional craniotomy. The aneurysm was discovered 6 months after surgery on a routine control angiography. The patient was successfully treated by trapping the parent vessel and excising the aneurysm. Histopathological findings were compatible with a true type of traumatic aneurysm. The possibility of this rare condition occurring highlights the risk of arterial injury during craniotomy. PMID:20121386

  1. Multiscale Modeling of Cortical Neural Networks

    NASA Astrophysics Data System (ADS)

    Torben-Nielsen, Benjamin; Stiefel, Klaus M.

    2009-09-01

    In this study, we describe efforts at modeling the electrophysiological dynamics of cortical networks in a multi-scale manner. Specifically, we describe the implementation of a network model composed of simple single-compartmental neuron models, in which a single complex multi-compartmental model of a pyramidal neuron is embedded. The network is capable of generating Δ (2 Hz, observed during deep sleep states) and γ (40 Hz, observed during wakefulness) oscillations, which are then imposed onto the multi-compartmental model, thus providing realistic, dynamic boundary conditions. We furthermore discuss the challenges and chances involved in multi-scale modeling of neural function.

  2. Genetic and epigenetic contributions to the cortical phenotype in mammals☆

    PubMed Central

    Larsen, DeLaine D.; Krubitzer, Leah

    2008-01-01

    One aspect of cortical organization, cortical field size, is variable both within and across species. The observed variability arises from a variety of sources, including genes intrinsic to the neocortex and a number of extrinsic and epigenetic factors. Genes intrinsic to the cortex are directly involved in the development and specification of cortical fields and are regulated from both signaling centers located outside of the neocortex, which secrete diffusible molecules, and the expression of transcription factors within the neocortex. In addition, extrinsic factors such as the type, location and density of sensory receptor arrays and how these receptor arrays are utilized, are also strongly related to cortical field size. Epigenetic factors including the relative activity patterns generated by the different types of physical stimuli in a given environment also contribute to differences in cortical organization, including cortical field size. Since both genetic and epigenetic factors contribute to cortical organization, some aspects of the cortical phenotype evolve, while other aspects of the cortical phenotype persist only if the environment in which an individual develops is relatively stable. PMID:18331904

  3. Overweight is not associated with cortical thickness alterations in children

    PubMed Central

    Sharkey, Rachel J.; Karama, Sherif; Dagher, Alain

    2015-01-01

    Introduction: Several studies report an association between body mass index (BMI) and cortical thickness in adults. Some studies demonstrate diffuse cortical thinning in obesity, while others report effects in areas that are associated with self-regulation, such as lateral prefrontal cortex. Methods: This study used multilevel modeling of data from the NIH Pediatric MRI Data Repository, a mixed longitudinal and cross-sectional database, to examine the relationship between cortical thickness and body weight in children. Cortical thickness was computed at 81,942 vertices of 716 MRI scans from 378 children aged between 4 and 18 years. Body mass index Z score for age was computed for each participant. We performed vertex-wise statistical analysis of the relationship between cortical thickness and BMI, accounting for age and gender. In addition, cortical thickness was extracted from regions of interest in prefrontal cortex and insula. Results: No significant association between cortical thickness and BMI was found, either by statistical parametric mapping or by region of interest analysis. Results remained negative when the analysis was restricted to children aged 12–18. Conclusions: The correlation between BMI and cortical thickness was not found in this large pediatric sample. The association between BMI and cortical thinning develops after adolescence. This has implications for the nature of the relationship between brain anatomy and weight gain. PMID:25698918

  4. Cortical maturation and myelination in healthy toddlers and young children.

    PubMed

    Deoni, Sean C L; Dean, Douglas C; Remer, Justin; Dirks, Holly; O'Muircheartaigh, Jonathan

    2015-07-15

    The maturation of cortical structures, and the establishment of their connectivity, are critical neurodevelopmental processes that support and enable cognitive and behavioral functioning. Measures of cortical development, including thickness, curvature, and gyrification have been extensively studied in older children, adolescents, and adults, revealing regional associations with cognitive performance, and alterations with disease or pathology. In addition to these gross morphometric measures, increased attention has recently focused on quantifying more specific indices of cortical structure, in particular intracortical myelination, and their relationship to cognitive skills, including IQ, executive functioning, and language performance. Here we analyze the progression of cortical myelination across early childhood, from 1 to 6 years of age, in vivo for the first time. Using two quantitative imaging techniques, namely T1 relaxation time and myelin water fraction (MWF) imaging, we characterize myelination throughout the cortex, examine developmental trends, and investigate hemispheric and gender-based differences. We present a pattern of cortical myelination that broadly mirrors established histological timelines, with somatosensory, motor and visual cortices myelinating by 1 year of age; and frontal and temporal cortices exhibiting more protracted myelination. Developmental trajectories, defined by logarithmic functions (increasing for MWF, decreasing for T1), were characterized for each of 68 cortical regions. Comparisons of trajectories between hemispheres and gender revealed no significant differences. Results illustrate the ability to quantitatively map cortical myelination throughout early neurodevelopment, and may provide an important new tool for investigating typical and atypical development. PMID:25944614

  5. Music perception: information flow within the human auditory cortices.

    PubMed

    Angulo-Perkins, Arafat; Concha, Luis

    2014-01-01

    Information processing of all acoustic stimuli involves temporal lobe regions referred to as auditory cortices, which receive direct afferents from the auditory thalamus. However, the perception of music (as well as speech or spoken language) is a complex process that also involves secondary and association cortices that conform a large functional network. Using different analytical techniques and stimulation paradigms, several studies have shown that certain areas are particularly sensitive to specific acoustic characteristics inherent to music (e.g., rhythm). This chapter reviews the functional anatomy of the auditory cortices, and highlights specific experiments that suggest the existence of distinct cortical networks for the perception of music and speech. PMID:25358716

  6. Prefrontal cortical minicolumn: from executive control to disrupted cognitive processing

    PubMed Central

    Casanova, Manuel F.

    2014-01-01

    The prefrontal cortex of the primate brain has a modular architecture based on the aggregation of neurons in minicolumnar arrangements having afferent and efferent connections distributed across many brain regions to represent, select and/or maintain behavioural goals and executive commands. Prefrontal cortical microcircuits are assumed to play a key role in the perception to action cycle that integrates relevant information about environment, and then selects and enacts behavioural responses. Thus, neurons within the interlaminar microcircuits participate in various functional states requiring the integration of signals across cortical layers and the selection of executive variables. Recent research suggests that executive abilities emerge from cortico-cortical interactions between interlaminar prefrontal cortical microcircuits, whereas their disruption is involved in a broad spectrum of neurologic and psychiatric disorders such as autism, schizophrenia, Alzheimer’s and drug addiction. The focus of this review is on the structural, functional and pathological approaches involving cortical minicolumns. Based on recent technological progress it has been demonstrated that microstimulation of infragranular cortical layers with patterns of microcurrents derived from supragranular layers led to an increase in cognitive performance. This suggests that interlaminar prefrontal cortical microcircuits are playing a causal role in improving cognitive performance. An important reason for the new interest in cortical modularity comes from both the impressive progress in understanding anatomical, physiological and pathological facets of cortical microcircuits and the promise of neural prosthetics for patients with neurological and psychiatric disorders. PMID:24531625

  7. Cortical maturation and myelination in healthy toddlers and young children

    PubMed Central

    Deoni, Sean C.L.; Dean, Douglas C.; Remer, Justin; Dirks, Holly; O’Muircheartaigh, Jonathan

    2015-01-01

    The maturation of cortical structures, and the establishment of their connectivity, are critical neurodevelopmental processes that support and enable cognitive and behavioral functioning. Measures of cortical development, including thickness, curvature, and gyrification have been extensively studied in older children, adolescents, and adults, revealing regional associations with cognitive performance, and alterations with disease or pathology. In addition to these gross morphometric measures, increased attention has recently focused on quantifying more specific indices of cortical structure, in particular intracortical myelination, and their relationship to cognitive skills, including IQ, executive functioning, and language performance. Here we analyze the progression of cortical myelination across early childhood, from 1 to 6 years of age, in vivo for the first time. Using two quantitative imaging techniques, namely T1 relaxation time and myelin water fraction (MWF) imaging, we characterize myelination throughout the cortex, examine developmental trends, and investigate hemispheric and gender-based differences. We present a pattern of cortical myelination that broadly mirrors established histological timelines, with somatosensory, motor and visual cortices myelinating by 1 year of age; and frontal and temporal cortices exhibiting more protracted myelination. Developmental trajectories, defined by logarithmic functions (increasing for MWF, decreasing for T1), were characterized for each of 68 cortical regions. Comparisons of trajectories between hemispheres and gender revealed no significant differences. Results illustrate the ability to quantitatively map cortical myelination throughout early neurodevelopment, and may provide an important new tool for investigating typical and atypical development. PMID:25944614

  8. Effects of polar cortical cytoskeleton and unbalanced cortical surface tension on intercellular bridge thinning during cytokinesis

    NASA Astrophysics Data System (ADS)

    Wang, Li; An, Mei-Wen; Li, Xiao-Na; Yang, Fang; Liu, Yang

    2011-12-01

    To probe the contributions of polar cortical cytoskeleton and the surface tension of daughter cells to intercellular bridge thinning dynamics during cytokinesis, we applied cytochalasin D (CD) or colchicine (COLC) in a highly localized manner to polar regions of dividing normal rat kidney (NRK) cells. We observed cellular morphological changes and analyzed the intercellular bridge thinning trajectories of dividing cells with different polar cortical characteristics. Global blebbistatin (BS) application was used to obtain cells losing active contractile force groups. Our results show that locally released CD or colchicine at the polar region caused inhibition of cytokinesis before ingression. Similar treatment at phases after ingression allowed completion of cytokinesis but dramatically influenced the trajectories of intercellular bridge thinning. Disturbing single polar cortical actin induced transformation of the intercellular bridge thinning process, and polar cortical tension controlled deformation time of intercellular bridges. Our study provides a feasible framework to induce and analyze the effects of local changes in mechanical properties of cellular components on single cellular cytokinesis.

  9. Extraction of the cerebral cortical boundaries from MRI for measurement of cortical thickness

    NASA Astrophysics Data System (ADS)

    Eskildsen, Simon F.; Uldahl, Mark; Ostergaard, Lasse R.

    2005-04-01

    Several neurodegenerative diseases, such as Alzheimer's disease, cause atrophy of the cerebral cortex. Measurements of cerebral cortical thickness and volume are used in the quantification and localization of atrophy. It is possible to measure the thickness of the cerebral cortex manually from magnetic resonance imaging, but partial volume effects, orthogonality problems, large amounts of manual labor and operator bias makes it difficult to conduct measurements on large patient populations. Automatic quantification and localization of atrophy is a highly desirable goal, as it facilitates the study of early anatomical changes and track disease progression on large populations. The first step in achieving this goal is to develop robust and accurate methods for measuring cortical thickness and volume automatically. We have developed a new method, capable of both extracting surface representations of the cortical boundaries from magnetic resonance imaging and measuring the cortical thickness. Experiments show that the developed method is robust and performs well on datasets of both healthy subjects and subjects suffering from Alzheimer's disease.

  10. Cortical Polarity of the RING Protein PAR-2 Is Maintained by Exchange Rate Kinetics at the Cortical-Cytoplasmic Boundary.

    PubMed

    Arata, Yukinobu; Hiroshima, Michio; Pack, Chan-Gi; Ramanujam, Ravikrishna; Motegi, Fumio; Nakazato, Kenichi; Shindo, Yuki; Wiseman, Paul W; Sawa, Hitoshi; Kobayashi, Tetsuya J; Brandão, Hugo B; Shibata, Tatsuo; Sako, Yasushi

    2016-08-23

    Cell polarity arises through the spatial segregation of polarity regulators. PAR proteins are polarity regulators that localize asymmetrically to two opposing cortical domains. However, it is unclear how the spatially segregated PAR proteins interact to maintain their mutually exclusive partitioning. Here, single-molecule detection analysis in Caenorhabditis elegans embryos reveals that cortical PAR-2 diffuses only short distances, and, as a result, most PAR-2 molecules associate and dissociate from the cortex without crossing into the opposing domain. Our results show that cortical PAR-2 asymmetry is maintained by the local exchange reactions that occur at the cortical-cytoplasmic boundary. Additionally, we demonstrate that local exchange reactions are sufficient to maintain cortical asymmetry in a parameter-free mathematical model. These findings suggest that anterior and posterior PAR proteins primarily interact through the cytoplasmic pool and not via cortical diffusion. PMID:27524610

  11. Object recognition by artificial cortical maps.

    PubMed

    Plebe, Alessio; Domenella, Rosaria Grazia

    2007-09-01

    Object recognition is one of the most important functions of the human visual system, yet one of the least understood, this despite the fact that vision is certainly the most studied function of the brain. We understand relatively well how several processes in the cortical visual areas that support recognition capabilities take place, such as orientation discrimination and color constancy. This paper proposes a model of the development of object recognition capability, based on two main theoretical principles. The first is that recognition does not imply any sort of geometrical reconstruction, it is instead fully driven by the two dimensional view captured by the retina. The second assumption is that all the processing functions involved in recognition are not genetically determined or hardwired in neural circuits, but are the result of interactions between epigenetic influences and basic neural plasticity mechanisms. The model is organized in modules roughly related to the main visual biological areas, and is implemented mainly using the LISSOM architecture, a recent neural self-organizing map model that simulates the effects of intercortical lateral connections. This paper shows how recognition capabilities, similar to those found in brain ventral visual areas, can develop spontaneously by exposure to natural images in an artificial cortical model. PMID:17604954

  12. A zonal model of cortical functions.

    PubMed

    Green, H S; Triffet, T

    1989-01-01

    A model of cortical functions is developed with the object of simulating the observed behavior of individual neurons organized in unit circuits and functional systems of the cerebellum, the cerebrum and the hippocampal formation. The neuronal model is capable of representing refractory and potentiated states, as well as the firing and lowest resting states. The unit circuits of each system consist of all common types of cells with known synaptic connections. In the cerebral system these unit circuits are interconnected to form columns as well as zones. A new discrete neural network equation, which takes account of interactions with the extracellular field, is proposed to simulate electrical activity in these circuits. A coherent theory of cortical activity and functions is derived that accounts for many of the observed phenomena, including those associated with the development of long-term potentiation and sequential memory. Three appendices are devoted to the theory of extracellular interactions, the derivation of non-linear network equations, and a computer program to simulate learning in the cortex. PMID:2779262

  13. Correlation of cerebral cortical morphology with behavior

    SciTech Connect

    Norton, S.

    1989-03-01

    Association between functional damage and damage to the central nervous system from toxic agents can be used to determine the value of behavioral tests as predictors of damage to the nervous system. Variability in data from behavioral tests may be caused, in part, by varying levels of structural differences in the nervous system. Stepwise multiple regression is one method for analyzing the relationship between variability in data resulting from linkage between functional and morphological or other parameters of the structure of the nervous system. As an example, the predictive value of four behavioral tests is assessed in detecting thinning of the cerebral cortex following gestational exposure of rats to ionizing radiation. In this analysis, there were seven independent variables for predicting cortical thickness. The sequence of number of times each variable was used in prediction, from most frequent to least frequent, was: angle of stride greater than negative geotaxis greater than continuous corridor greater than body weight greater than width of stride greater than length of stride greater than reflex suspension. The data support the concept that there are varying degrees of predictive associations between these functional and cortical parameters.

  14. Integrated cortical structural marker for Alzheimer's disease.

    PubMed

    Ming, Jing; Harms, Michael P; Morris, John C; Beg, M Faisal; Wang, Lei

    2015-01-01

    In this article, we propose an approach to integrate cortical morphology measures for improving the discrimination of individuals with and without very mild Alzheimer's disease (AD). FreeSurfer was applied to scans collected from 83 participants with very mild AD and 124 cognitively normal individuals. We generated cortex thickness, white matter convexity (aka "sulcal depth"), and white matter surface metric distortion measures on a normalized surface atlas in this first study to integrate high resolution gray matter thickness and white matter surface geometric measures in identifying very mild AD. Principal component analysis was applied to each individual structural measure to generate eigenvectors. Discrimination power based on individual and combined measures are compared, based on stepwise logistic regression and 10-fold cross-validation. Global AD likelihood index and surface-based likelihood maps were also generated. Our results show complementary patterns on the cortical surface between thickness, which reflects gray matter atrophy, convexity, which reflects white matter sulcal depth changes and metric distortion, which reflects white matter surface area changes. The classifier integrating all 3 types of surface measures significantly improved classification performance compared with classification based on single measures. The principal component analysis-based approach provides a framework for achieving high discrimination power by integrating high-dimensional data, and this method could be very powerful in future studies for early diagnosis of diseases that are known to be associated with abnormal gyral and sulcal patterns. PMID:25444604

  15. Many Specialists for Suppressing Cortical Excitation

    PubMed Central

    Burkhalter, Andreas

    2008-01-01

    Cortical computations are critically dependent on GABA-releasing neurons for dynamically balancing excitation with inhibition that is proportional to the overall level of activity. Although it is widely accepted that there are multiple types of interneurons, defining their identities based on qualitative descriptions of morphological, molecular and physiological features has failed to produce a universally accepted ‘parts list’, which is needed to understand the roles that interneurons play in cortical processing. A list of features has been published by the Petilla Interneurons Nomenclature Group, which represents an important step toward an unbiased classification of interneurons. To this end some essential features have recently been studied quantitatively and their association was examined using multidimensional cluster analyses. These studies revealed at least 3 distinct electrophysiological, 6 morphological and 15 molecular phenotypes. This is a conservative estimate of the number of interneuron types, which almost certainly will be revised as more quantitative studies will be performed and similarities will be defined objectively. It is clear that interneurons are organized with physiological attributes representing the most general, molecular characteristics the most detailed and morphological features occupying the middle ground. By themselves, none of these features are sufficient to define classes of interneurons. The challenge will be to determine which features belong together and how cell type-specific feature combinations are genetically specified. PMID:19225588

  16. Cortical cartography reveals political and physical maps.

    PubMed

    Loring, David W; Gaillard, William Davis; Bookheimer, Susan Y; Meador, Kimford J; Ojemann, Jeffrey G

    2014-05-01

    Advances in functional imaging have provided noninvasive techniques to probe brain organization of multiple constructs including language and memory. Because of high overall rates of agreements with older techniques, including Wada testing and cortical stimulation mapping (CSM), some have proposed that those approaches should be largely abandoned because of their invasiveness, and replaced with noninvasive functional imaging methods. High overall agreement, however, is based largely on concordant language lateralization in series dominated by cases of typical cerebral dominance. Advocating a universal switch from Wada testing and cortical stimulation mapping to functional magnetic resonance imaging (fMRI) or magnetoencephalography (MEG) ignores the differences in specific expertise across epilepsy centers, many of which often have greater skill with one approach rather than the other, and that Wada, CSM, fMRI, and MEG protocols vary across institutions resulting in different outcomes and reliability. Specific patient characteristics also affect whether Wada or CSM might influence surgical management, making it difficult to accept broad recommendations against currently useful clinical tools. Although the development of noninvasive techniques has diminished the frequency of more invasive approaches, advocating their use to replace Wada testing and CSM across all epilepsy surgery programs without consideration of the different skills, protocols, and expertise at any given center site is ill-advised. PMID:24815217

  17. Ultrasonic wave propagation in cortical bone mimics

    NASA Astrophysics Data System (ADS)

    Dodd, Simon P.; Cunningham, James L.; Miles, Anthony W.; Humphrey, Victor F.; Gheduzzi, Sabina

    2004-10-01

    Understanding the velocity and attenuation of ultrasonic waves in cortical bone is important for studies of osteoporosis and fractures. In particular, propagation in free- and water-loaded acrylic plates, with a thickness range of around 1-6 mm, has been widely used to mimic cortical bone behavior. A theoretical investigation of Lamb mode propagation at 200 kHz in free- and water-loaded acrylic plates revealed a marked difference in the form of their velocity and attenuation dispersion curves as a function of frequency thickness product. In experimental studies, this difference between free and loaded plates is not seen. Over short measurement distances, the results for both free and loaded plates are consistent with previous modeling and experimental studies: for thicker plates (above 3-4 mm), the velocity calculated using the first arrival signal is a lateral wave comparable with the longitudinal velocity. As the plate thickness decreases, the velocity approaches the S0 Lamb mode value. WAVE2000 modeling of the experimental setup agrees with experimental data. The data are also used to test a hypothesis that for thin plates the velocity approaches the corresponding S0 Lamb mode velocity at large measurement distances or when different arrival time criteria are used. [Work supported by Action Medical Research.

  18. Massive cortical reorganization in sighted Braille readers

    PubMed Central

    Siuda-Krzywicka, Katarzyna; Bola, Łukasz; Paplińska, Małgorzata; Sumera, Ewa; Jednoróg, Katarzyna; Marchewka, Artur; Śliwińska, Magdalena W; Amedi, Amir; Szwed, Marcin

    2016-01-01

    The brain is capable of large-scale reorganization in blindness or after massive injury. Such reorganization crosses the division into separate sensory cortices (visual, somatosensory...). As its result, the visual cortex of the blind becomes active during tactile Braille reading. Although the possibility of such reorganization in the normal, adult brain has been raised, definitive evidence has been lacking. Here, we demonstrate such extensive reorganization in normal, sighted adults who learned Braille while their brain activity was investigated with fMRI and transcranial magnetic stimulation (TMS). Subjects showed enhanced activity for tactile reading in the visual cortex, including the visual word form area (VWFA) that was modulated by their Braille reading speed and strengthened resting-state connectivity between visual and somatosensory cortices. Moreover, TMS disruption of VWFA activity decreased their tactile reading accuracy. Our results indicate that large-scale reorganization is a viable mechanism recruited when learning complex skills. DOI: http://dx.doi.org/10.7554/eLife.10762.001 PMID:26976813

  19. Cable energy function of cortical axons

    PubMed Central

    Ju, Huiwen; Hines, Michael L.; Yu, Yuguo

    2016-01-01

    Accurate estimation of action potential (AP)-related metabolic cost is essential for understanding energetic constraints on brain connections and signaling processes. Most previous energy estimates of the AP were obtained using the Na+-counting method, which seriously limits accurate assessment of metabolic cost of ionic currents that underlie AP conduction along the axon. Here, we first derive a full cable energy function for cortical axons based on classic Hodgkin-Huxley (HH) neuronal equations and then apply the cable energy function to precisely estimate the energy consumption of AP conduction along axons with different geometric shapes. Our analytical approach predicts an inhomogeneous distribution of metabolic cost along an axon with either uniformly or nonuniformly distributed ion channels. The results show that the Na+-counting method severely underestimates energy cost in the cable model by 20–70%. AP propagation along axons that differ in length may require over 15% more energy per unit of axon area than that required by a point model. However, actual energy cost can vary greatly depending on axonal branching complexity, ion channel density distributions, and AP conduction states. We also infer that the metabolic rate (i.e. energy consumption rate) of cortical axonal branches as a function of spatial volume exhibits a 3/4 power law relationship. PMID:27439954

  20. Astrocytes regulate cortical state switching in vivo

    PubMed Central

    Poskanzer, Kira E.; Yuste, Rafael

    2016-01-01

    The role of astrocytes in neuronal function has received increasing recognition, but disagreement remains about their function at the circuit level. Here we use in vivo two-photon calcium imaging of neocortical astrocytes while monitoring the activity state of the local neuronal circuit electrophysiologically and optically. We find that astrocytic calcium activity precedes spontaneous circuit shifts to the slow-oscillation–dominated state, a neocortical rhythm characterized by synchronized neuronal firing and important for sleep and memory. Further, we show that optogenetic activation of astrocytes switches the local neuronal circuit to this slow-oscillation state. Finally, using two-photon imaging of extracellular glutamate, we find that astrocytic transients in glutamate co-occur with shifts to the synchronized state and that optogenetically activated astrocytes can generate these glutamate transients. We conclude that astrocytes can indeed trigger the low-frequency state of a cortical circuit by altering extracellular glutamate, and therefore play a causal role in the control of cortical synchronizations. PMID:27122314

  1. Astrocytes regulate cortical state switching in vivo.

    PubMed

    Poskanzer, Kira E; Yuste, Rafael

    2016-05-10

    The role of astrocytes in neuronal function has received increasing recognition, but disagreement remains about their function at the circuit level. Here we use in vivo two-photon calcium imaging of neocortical astrocytes while monitoring the activity state of the local neuronal circuit electrophysiologically and optically. We find that astrocytic calcium activity precedes spontaneous circuit shifts to the slow-oscillation-dominated state, a neocortical rhythm characterized by synchronized neuronal firing and important for sleep and memory. Further, we show that optogenetic activation of astrocytes switches the local neuronal circuit to this slow-oscillation state. Finally, using two-photon imaging of extracellular glutamate, we find that astrocytic transients in glutamate co-occur with shifts to the synchronized state and that optogenetically activated astrocytes can generate these glutamate transients. We conclude that astrocytes can indeed trigger the low-frequency state of a cortical circuit by altering extracellular glutamate, and therefore play a causal role in the control of cortical synchronizations. PMID:27122314

  2. Thermographic stress analysis in cortical bone.

    PubMed

    Vanderby, R; Kohles, S S

    1991-11-01

    Under adiabatic (or near adiabatic) conditions a volumetric change in an elastic material will produce a corresponding change in temperature. Based upon this principle, thermographic stress analysis (TSA) measures changes in surface heat flux (which are related to changes in surface temperature) and relates them to a coupled form of strains or stresses. To demonstrate the feasibility of using this technique for biomechanical applications, we thermographically measured heat flux from loaded specimens of cortical bone and correlated the results with strain gage data. Regular parallelepipeds were cut from the cortex of bovine femora and loaded sinusoidally at 20 Hz. At this rate of loading, mechanically induced changes in surface temperature could be sampled (via heat flux) prior to a measureable attenuation of the thermoelastic effect. Correlation coefficients demonstrated a significant linear relationship between TSA and measured and computed mechanical parameters (stress, strain, first strain invariant, and strain energy density). TSA therefore appears to be a promising technology for experimental stress analysis in cortical bone. PMID:1762439

  3. Cable energy function of cortical axons.

    PubMed

    Ju, Huiwen; Hines, Michael L; Yu, Yuguo

    2016-01-01

    Accurate estimation of action potential (AP)-related metabolic cost is essential for understanding energetic constraints on brain connections and signaling processes. Most previous energy estimates of the AP were obtained using the Na(+)-counting method, which seriously limits accurate assessment of metabolic cost of ionic currents that underlie AP conduction along the axon. Here, we first derive a full cable energy function for cortical axons based on classic Hodgkin-Huxley (HH) neuronal equations and then apply the cable energy function to precisely estimate the energy consumption of AP conduction along axons with different geometric shapes. Our analytical approach predicts an inhomogeneous distribution of metabolic cost along an axon with either uniformly or nonuniformly distributed ion channels. The results show that the Na(+)-counting method severely underestimates energy cost in the cable model by 20-70%. AP propagation along axons that differ in length may require over 15% more energy per unit of axon area than that required by a point model. However, actual energy cost can vary greatly depending on axonal branching complexity, ion channel density distributions, and AP conduction states. We also infer that the metabolic rate (i.e. energy consumption rate) of cortical axonal branches as a function of spatial volume exhibits a 3/4 power law relationship. PMID:27439954

  4. Dendritic spikes enhance stimulus selectivity in cortical neurons in vivo.

    PubMed

    Smith, Spencer L; Smith, Ikuko T; Branco, Tiago; Häusser, Michael

    2013-11-01

    Neuronal dendrites are electrically excitable: they can generate regenerative events such as dendritic spikes in response to sufficiently strong synaptic input. Although such events have been observed in many neuronal types, it is not well understood how active dendrites contribute to the tuning of neuronal output in vivo. Here we show that dendritic spikes increase the selectivity of neuronal responses to the orientation of a visual stimulus (orientation tuning). We performed direct patch-clamp recordings from the dendrites of pyramidal neurons in the primary visual cortex of lightly anaesthetized and awake mice, during sensory processing. Visual stimulation triggered regenerative local dendritic spikes that were distinct from back-propagating action potentials. These events were orientation tuned and were suppressed by either hyperpolarization of membrane potential or intracellular blockade of NMDA (N-methyl-d-aspartate) receptors. Both of these manipulations also decreased the selectivity of subthreshold orientation tuning measured at the soma, thus linking dendritic regenerative events to somatic orientation tuning. Together, our results suggest that dendritic spikes that are triggered by visual input contribute to a fundamental cortical computation: enhancing orientation selectivity in the visual cortex. Thus, dendritic excitability is an essential component of behaviourally relevant computations in neurons. PMID:24162850

  5. A cognitive neuroprosthetic that uses cortical stimulation for somatosensory feedback

    NASA Astrophysics Data System (ADS)

    Klaes, Christian; Shi, Ying; Kellis, Spencer; Minxha, Juri; Revechkis, Boris; Andersen, Richard A.

    2014-10-01

    Objective. Present day cortical brain-machine interfaces (BMIs) have made impressive advances using decoded brain signals to control extracorporeal devices. Although BMIs are used in a closed-loop fashion, sensory feedback typically is visual only. However medical case studies have shown that the loss of somesthesis in a limb greatly reduces the agility of the limb even when visual feedback is available. Approach. To overcome this limitation, this study tested a closed-loop BMI that utilizes intracortical microstimulation to provide ‘tactile’ sensation to a non-human primate. Main result. Using stimulation electrodes in Brodmann area 1 of somatosensory cortex (BA1) and recording electrodes in the anterior intraparietal area, the parietal reach region and dorsal area 5 (area 5d), it was found that this form of feedback can be used in BMI tasks. Significance. Providing somatosensory feedback has the poyential to greatly improve the performance of cognitive neuroprostheses especially for fine control and object manipulation. Adding stimulation to a BMI system could therefore improve the quality of life for severely paralyzed patients.

  6. Modeling of cortical signals using echo state networks

    NASA Astrophysics Data System (ADS)

    Zhou, Hanying; Wang, Yongji; Huang, Jiangshuai

    2009-10-01

    Diverse modeling frameworks have been utilized with the ultimate goal of translating brain cortical signals into prediction of visible behavior. The inputs to these models are usually multidimensional neural recordings collected from relevant regions of a monkey's brain while the outputs are the associated behavior which is typically the 2-D or 3-D hand position of a primate. Here our task is to set up a proper model in order to figure out the move trajectories by input the neural signals which are simultaneously collected in the experiment. In this paper, we propose to use Echo State Networks (ESN) to map the neural firing activities into hand positions. ESN is a newly developed recurrent neural network(RNN) model. Besides its dynamic property and short term memory just as other recurrent neural networks have, it has a special echo state property which endows it with the ability to model nonlinear dynamic systems powerfully. What distinguished it from transitional recurrent neural networks most significantly is its special learning method. In this paper we train this net with a refined version of its typical training method and get a better model.

  7. Cortical entropy changes with general anaesthesia: theory and experiment.

    PubMed

    Sleigh, J W; Steyn-Ross, D A; Steyn-Ross, M L; Grant, C; Ludbrook, G

    2004-08-01

    Commonly used general anaesthetics cause a decrease in the spectral entropy of the electroencephalogram as the patient transits from the conscious to the unconscious state. Although the spectral entropy is a configurational entropy, it is plausible that the spectral entropy may be acting as a reliable indicator of real changes in cortical neuronal interactions. Using a mean field theory, the activity of the cerebral cortex may be modelled as fluctuations in mean soma potential around equilibrium states. In the adiabatic limit, the stochastic differential equations take the form of an Ornstein-Uhlenbeck process. It can be shown that spectral entropy is a logarithmic measure of the rate of synaptic interaction. This model predicts that the spectral entropy should decrease abruptly from values approximately 1.0 to values of approximately 0.7 as the patient becomes unconscious during induction of general anaesthesia, and then not decrease significantly on further deepening of anaesthesia. These predictions were compared with experimental results in which electrocorticograms and brain concentrations of propofol were recorded in seven sheep during induction of anaesthesia with intravenous propofol. The observed changes in spectral entropy agreed with the theoretical predictions. We conclude that spectral entropy may be a sensitive monitor of the consciousness-unconsciousness transition, rather than a progressive indicator of anaesthetic drug effect. PMID:15382831

  8. Functional Clusters, Hubs, and Communities in the Cortical Microconnectome.

    PubMed

    Shimono, Masanori; Beggs, John M

    2015-10-01

    Although relationships between networks of different scales have been observed in macroscopic brain studies, relationships between structures of different scales in networks of neurons are unknown. To address this, we recorded from up to 500 neurons simultaneously from slice cultures of rodent somatosensory cortex. We then measured directed effective networks with transfer entropy, previously validated in simulated cortical networks. These effective networks enabled us to evaluate distinctive nonrandom structures of connectivity at 2 different scales. We have 4 main findings. First, at the scale of 3-6 neurons (clusters), we found that high numbers of connections occurred significantly more often than expected by chance. Second, the distribution of the number of connections per neuron (degree distribution) had a long tail, indicating that the network contained distinctively high-degree neurons, or hubs. Third, at the scale of tens to hundreds of neurons, we typically found 2-3 significantly large communities. Finally, we demonstrated that communities were relatively more robust than clusters against shuffling of connections. We conclude the microconnectome of the cortex has specific organization at different scales, as revealed by differences in robustness. We suggest that this information will help us to understand how the microconnectome is robust against damage. PMID:25336598

  9. Low-dimensional dynamics of resting-state cortical activity.

    PubMed

    Mehrkanoon, Saeid; Breakspear, Michael; Boonstra, Tjeerd W

    2014-05-01

    Endogenous brain activity supports spontaneous human thought and shapes perception and behavior. Connectivity-based analyses of endogenous, or resting-state, functional magnetic resonance imaging (fMRI) data have revealed the existence of a small number of robust networks which have a rich spatial structure. Yet the temporal information within fMRI data is limited, motivating the complementary analysis of electrophysiological recordings such as electroencephalography (EEG). Here we provide a novel method based on multivariate time-frequency interdependence to reconstruct the principal resting-state network dynamics in human EEG data. The stability of network expression across subjects is assessed using resampling techniques. We report the presence of seven robust networks, with distinct topographic organizations and high frequency (∼ 5-45 Hz) fingerprints, nested within slow temporal sequences that build up and decay over several orders of magnitude. Interestingly, all seven networks are expressed concurrently during these slow dynamics, although there is a temporal asymmetry in the pattern of their formation and dissolution. These analyses uncover the complex temporal character of endogenous cortical fluctuations and, in particular, offer an opportunity to reconstruct the low dimensional linear subspace in which they unfold. PMID:24104726

  10. Asymmetric frontal cortical activity predicts effort expenditure for reward.

    PubMed

    Hughes, David M; Yates, Mark J; Morton, Emma E; Smillie, Luke D

    2015-07-01

    An extensive literature shows that greater left, relative to right, frontal cortical activity (LFA) is involved in approach-motivated affective states and reflects stable individual differences in approach motivation. However, relatively few studies have linked LFA to behavioral indices of approach motivation. In this study, we examine the relation between LFA and effort expenditure for reward, a behavioral index of approach motivation. LFA was calculated for 51 right-handed participants (55% female) using power spectral analysis of electroencephalogram recorded at rest. Participants also completed the effort expenditure for rewards task (EEfRT), which presents a series of trials requiring a choice between a low-reward low-effort task and a high-reward high-effort task. We found that individuals with greater resting LFA were more willing to expend greater effort in the pursuit of larger rewards, particularly when reward delivery was less likely. Our findings offer a more nuanced understanding of the motivational significance of LFA, in terms of processes that mitigate the effort- and uncertainty-related costs of pursuing rewarding goals. PMID:25479792

  11. Using melanopsin to study G protein signaling in cortical neurons.

    PubMed

    McGregor, K M; Bécamel, C; Marin, P; Andrade, R

    2016-09-01

    Our understanding of G protein-coupled receptors (GPCRs) in the central nervous system (CNS) has been hampered by the limited availability of tools allowing for the study of their signaling with precise temporal control. To overcome this, we tested the utility of the bistable mammalian opsin melanopsin to examine G protein signaling in CNS neurons. Specifically, we used biolistic (gene gun) approaches to transfect melanopsin into cortical pyramidal cells maintained in organotypic slice culture. Whole cell recordings from transfected neurons indicated that application of blue light effectively activated the transfected melanopsin to elicit the canonical biphasic modulation of membrane excitability previously associated with the activation of GPCRs coupling to Gαq-11 Remarkably, full mimicry of exogenous agonist concentration could be obtained with pulses as short as a few milliseconds, suggesting that their triggering required a single melanopsin activation-deactivation cycle. The resulting temporal control over melanopsin activation allowed us to compare the activation kinetics of different components of the electrophysiological response. We also replaced the intracellular loops of melanopsin with those of the 5-HT2A receptor to create a light-activated GPCR capable of interacting with the 5-HT2A receptor interacting proteins. The resulting chimera expressed weak activity but validated the potential usefulness of melanopsin as a tool for the study of G protein signaling in CNS neurons. PMID:27306679

  12. Vestibular receptors contribute to cortical auditory evoked potentials☆

    PubMed Central

    Todd, Neil P.M.; Paillard, Aurore C.; Kluk, Karolina; Whittle, Elizabeth; Colebatch, James G.

    2014-01-01

    Acoustic sensitivity of the vestibular apparatus is well-established, but the contribution of vestibular receptors to the late auditory evoked potentials of cortical origin is unknown. Evoked potentials from 500 Hz tone pips were recorded using 70 channel EEG at several intensities below and above the vestibular acoustic threshold, as determined by vestibular evoked myogenic potentials (VEMPs). In healthy subjects both auditory mid- and long-latency auditory evoked potentials (AEPs), consisting of Na, Pa, N1 and P2 waves, were observed in the sub-threshold conditions. However, in passing through the vestibular threshold, systematic changes were observed in the morphology of the potentials and in the intensity dependence of their amplitude and latency. These changes were absent in a patient without functioning vestibular receptors. In particular, for the healthy subjects there was a fronto-central negativity, which appeared at about 42 ms, referred to as an N42, prior to the AEP N1. Source analysis of both the N42 and N1 indicated involvement of cingulate cortex, as well as bilateral superior temporal cortex. Our findings are best explained by vestibular receptors contributing to what were hitherto considered as purely auditory evoked potentials and in addition tentatively identify a new component that appears to be primarily of vestibular origin. PMID:24321822

  13. Suppression of competing speech through entrainment of cortical oscillations.

    PubMed

    Horton, Cort; D'Zmura, Michael; Srinivasan, Ramesh

    2013-06-01

    People are highly skilled at attending to one speaker in the presence of competitors, but the neural mechanisms supporting this remain unclear. Recent studies have argued that the auditory system enhances the gain of a speech stream relative to competitors by entraining (or "phase-locking") to the rhythmic structure in its acoustic envelope, thus ensuring that syllables arrive during periods of high neuronal excitability. We hypothesized that such a mechanism could also suppress a competing speech stream by ensuring that syllables arrive during periods of low neuronal excitability. To test this, we analyzed high-density EEG recorded from human adults while they attended to one of two competing, naturalistic speech streams. By calculating the cross-correlation between the EEG channels and the speech envelopes, we found evidence of entrainment to the attended speech's acoustic envelope as well as weaker yet significant entrainment to the unattended speech's envelope. An independent component analysis (ICA) decomposition of the data revealed sources in the posterior temporal cortices that displayed robust correlations to both the attended and unattended envelopes. Critically, in these components the signs of the correlations when attended were opposite those when unattended, consistent with the hypothesized entrainment-based suppressive mechanism. PMID:23515789

  14. Simultaneous estimation of cortical activity during social interactions by using EEG hyperscannings.

    PubMed

    Astolfi, L; Cincotti, F; Mattia, D; De Vico Fallani, F; Salinari, S; Vecchiato, G; Toppi, J; Wilke, C; Doud, A; Yuan, H; He, B; Babiloni, F

    2010-01-01

    In this paper we show how the possibility of recording simultaneously the cerebral neuroelectric activity in different subjects (EEG hyperscanning) during the execution of different tasks could return useful information about the "internal" cerebral state of the subjects. We present the results obtained by EEG hyperscannings during ecological task (such as the execution of a card game) as well as that obtained in a series of couples of subjects during the performance of the Prisoner's Dilemma Game. The simultaneous recordings of couples of interacting subjects allows to observe and to model directly the neural signature of human interactions in order to understand the cerebral processes generating and generated by social cooperation or competition. Results obtained in a study of different groups recorded during the card game revealed a larger activity in prefrontal and anterior cingulated cortex in different frequency bands for the player that leads the game when compared to other players. Results collected in a population of 10 subjects during the performance of the Prisoner's Dilemma suggested that the most consistently activated structure is the orbitofrontal region (roughly described by the Brodmann area 10) during the condition of competition in both the tasks. It could be speculated whether the pattern of cortical connectivity between different cortical areas in different subjects could be employed as a tool for assessing the outcome of the task in advance. PMID:21096219

  15. Increased Cortical Extracellular Adenosine Correlates with Seizure Termination

    PubMed Central

    Van Gompel, Jamie J.; Bower, Mark R.; Worrell, Gregory A.; Stead, Matt; Chang, Su-Youne; Goerss, Stephan J.; Kim, Inyong; Bennet, Kevin E.; Meyer, Fredric B.; Marsh, W. Richard; Blaha, Charles D.; Lee, Kendall H.

    2014-01-01

    Objective Seizures are currently defined by their electrographic features. However, neuronal networks are intrinsically dependent upon neurotransmitters of which little is known regarding their peri-ictal dynamics. Evidence supports adenosine as having a prominent role in seizure termination, as its administration can terminate and reduce seizures in animal models. Further, microdialysis studies in humans suggest adenosine is elevated peri-ictally, but the relationship to the seizure is obscured by its temporal measurement limitations. Because electrochemical techniques can provide vastly superior temporal resolution, we test the hypothesis that extracellular adenosine concentrations rise during seizure termination in an animal model and humans using electrochemistry. Methods White farm swine (n=45) were used in an acute cortical model of epilepsy and 10 human epilepsy patients were studied during intraoperative electrocorticography (Ecog). Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) based fast scan cyclic voltametry (FSCV) and fixed potential amperometry were obtained utilizing an adenosine specific triangular waveform or biosensors respectively. Results Simultaneous Ecog and electrochemistry demonstrated an average adenosine rise of 260% compared to baseline at 7.5 ± 16.9 seconds with amperometry (n=75 events) and 2.6 ± 11.2 seconds with FSCV (n=15 events) prior to electrographic seizure termination. In agreement with these animal data, adenosine elevation prior to seizure termination in a human patient utilizing FSCV was also seen. Significance Simultaneous Ecog and electrochemical recording supports the hypothesis that adenosine rises prior to seizure termination, suggesting that adenosine itself may be responsible for seizure termination. Future work using intraoperative WINCS based FSCV recording may help to elucidate the precise relationship between adenosine and seizure termination. PMID:24483230

  16. Preference for Sucrose Solutions Modulates Taste Cortical Activity in Humans.

    PubMed

    Jacquin-Piques, Agnès; Mouillot, Thomas; Gigot, Vincent; Meillon, Sophie; Leloup, Corinne; Penicaud, Luc; Brondel, Laurent

    2016-09-01

    High time resolution is required to reliably measure neuronal activity in the gustatory cortex in response to taste stimuli. Hedonic aspects of gustatory processing have never been explored using gustatory evoked potentials (GEPs), a high-time-resolution technique. Our aim was to study cerebral processing of hedonic taste in humans using GEPs in response to sucrose solutions in subjects with different ratings of pleasantness regarding sucrose. In this exploratory study, 30 healthy volunteers were randomly stimulated with 3 sucrose solutions. The sucrose stimulus was presented to the tongue for 1s 20 times. GEPs were recorded from 9 cortical sites with EEG sensors at Cz, Fz, Pz, C3, C4, F3, F4, Fp1, and Fp2 (10/20 system). The main result was that subjects who preferred the high-concentration (20g/100mL) sucrose solution had higher GEP amplitudes on the Pz, Cz, and Fz electrodes than did subjects who preferred the low-concentration (5g/100mL) or the moderate-concentration (10g/100mL) solutions regardless of stimulus intensity. The difference in P1N1 amplitude on the Pz, Cz, and Fz electrodes according to sucrose preference of the subjects was described with stronger significance with stimulation by the 20 g-sucrose solution than by the 5 and 10g sucrose solutions. Using the reliable and safe GEP technique, we provide an original demonstration of variability of the gustatory response on the Pz, Cz, and Fz electrodes according to a sweet preference in humans. Further studies are needed to correlate the electric signal recorded by surface electrodes to the neural generator. PMID:27235187

  17. Accommodative response and cortical activity during sustained attention.

    PubMed

    Poltavski, Dmitri V; Biberdorf, David; Petros, Thomas V

    2012-06-15

    Greater accommodative lag and vergence deficits have been linked to attentional deficits similar to those observed in Attention Deficit Hyperactivity Disorder (ADHD). The purpose of the present study was to assess the effect of accommodative-vergence stress on a measure of sustained attention (Conners CPT) used in the diagnosis of ADHD. Twenty-seven normal non-ADHD adults completed the Conners CPT twice: wearing -2.00 D lenses and normally (without the -2.00 D lenses) in a counterbalanced order with at least 24 h between the sessions. Simultaneous recording of participants' dynamic accommodative responses was performed from the right eye using the Grand Seiko WAM-5500 auto-refractor and electroencephalographic activity (EEG) in the left prefrontal region using the Neurosky Mindset headset. The results demonstrated a significantly greater accommodative lag in the -2.00 D stress condition and a significantly poorer performance on the Conners CPT as indexed by slower reaction time, greater standard error of hit reaction time, grater response variability, poorer stimulus detectability and a greater number of perseverations. No differences were observed on measures of EEG in the theta (4-7 Hz), alpha (8-12 Hz), and beta (12-20 Hz) bands. Moreover, when directly juxtaposed with each EEG band in multiple linear regression analyses, greater accommodative lag in the stress condition was significantly associated with a greater probability of clinical classification on the Conners CPT, and was also marginally predictive of the number of omissions recorded in the stress condition. The results demonstrated that sustained attention can be influenced by such factors as accommodative-vergence stress and suggest that bottom-up processes can contribute to and potentially exacerbate attentional problems in individuals with ADHD. The study also showed that cortical dysfunction (while sufficient) may not be a necessary condition for attentional deficits. PMID:22580016

  18. Uncovering cortical MEG responses to listened audiobook stories.

    PubMed

    Koskinen, M; Seppä, M

    2014-10-15

    Naturalistic stimuli, such as normal speech and narratives, are opening up intriguing prospects in neuroscience, especially when merging neuroimaging with machine learning methodology. Here we propose a task-optimized spatial filtering strategy for uncovering individual magnetoencephalographic (MEG) responses to audiobook stories. Ten subjects listened to 1-h-long recording once, as well as to 48 repetitions of a 1-min-long speech passage. Employing response replicability as statistical validity and utilizing unsupervised learning methods, we trained spatial filters that were able to generalize over datasets of an individual. For this blind-signal-separation (BSS) task, we derived a version of multi-set similarity-constrained canonical correlation analysis (SimCCA) that theoretically provides maximal signal-to-noise ratio (SNR) in this setting. Irrespective of significant noise in unaveraged MEG traces, the method successfully uncovered feasible time courses up to ~120 Hz, with the most prominent signals below 20 Hz. Individual trial-to-trial correlations of such time courses reached the level of 0.55 (median 0.33 in the group) at ~0.5 Hz, with considerable variation between subjects. By this filtering, the SNR increased up to 20 times. In comparison, independent component analysis (ICA) or principal component analysis (PCA) did not improve SNR notably. The validity of the extracted brain signals was further assessed by inspecting their associations with the stimulus, as well as by mapping the contributing cortical signal sources. The results indicate that the proposed methodology effectively reduces noise in MEG recordings to that extent that brain responses can be seen to nonrecurring audiobook stories. The study paves the way for applications aiming at accurately modeling the stimulus-response-relationship by tackling the response variability, as well as for real-time monitoring of brain signals of individuals in naturalistic experimental conditions. PMID

  19. Distinct Behaviors of Neural Stem and Progenitor Cells Underlie Cortical Neurogenesis

    PubMed Central

    NOCTOR, STEPHEN C.; MARTÍNEZ-CERDEÑO, VERÓNICA; KRIEGSTEIN, ARNOLD R.

    2009-01-01

    Neocortical precursor cells undergo symmetric and asymmetric divisions while producing large numbers of diverse cortical cell types. In Drosophila, cleavage plane orientation dictates the inheritance of fate-determinants and the symmetry of newborn daughter cells during neuroblast cell divisions. One model for predicting daughter cell fate in the mammalian neocortex is also based on cleavage plane orientation. Precursor cell divisions with a cleavage plane orientation that is perpendicular with respect to the ventricular surface (vertical) are predicted to be symmetric, while divisions with a cleavage plane orientation that is parallel to the surface (horizontal) are predicted to be asymmetric neurogenic divisions. However, analysis of cleavage plane orientation at the ventricle suggests that the number of predicted neurogenic divisions might be insufficient to produce large amounts of cortical neurons. To understand factors that correlate with the symmetry of cell divisions, we examined rat neocortical precursor cells in situ through real-time imaging, marker analysis, and electrophysiological recordings. We find that cleavage plane orientation is more closely associated with precursor cell type than with daughter cell fate, as commonly thought. Radial glia cells in the VZ primarily divide with a vertical orientation throughout cortical development and undergo symmetric or asymmetric self-renewing divisions depending on the stage of development. In contrast, most intermediate progenitor cells divide in the subventricular zone with a horizontal orientation and produce symmetric daughter cells. We propose a model for predicting daughter cell fate that considers precursor cell type, stage of development, and the planar segregation of fate determinants. PMID:18288691

  20. Evoked Potentials in Motor Cortical Local Field Potentials Reflect Task Timing and Behavioral Performance

    PubMed Central

    Confais, Joachim; Ponce-Alvarez, Adrián; Diesmann, Markus; Riehle, Alexa

    2010-01-01

    Evoked potentials (EPs) are observed in motor cortical local field potentials (LFPs) during movement execution (movement-related potentials [MRPs]) and in response to relevant visual cues (visual evoked potentials [VEPs]). Motor cortical EPs may be directionally selective, but little is known concerning their relation to other aspects of motor behavior, such as task timing and performance. We recorded LFPs in motor cortex of two monkeys during performance of a precued arm-reaching task. A time cue at the start of each trial signaled delay duration and thereby the pace of the task and the available time for movement preparation. VEPs and MRPs were strongly modulated by the delay duration, VEPs being systematically larger in short-delay trials and MRPs larger in long-delay trials. Despite these systematic modulations related to the task timing, directional selectivity was similar in short and long trials. The behavioral reaction time was positively correlated with MRP size and negatively correlated with VEP size, within sessions. In addition, the behavioral performance improved across sessions, in parallel with a slow decrease in the size of VEPs and MRPs. Our results clearly show the strong influence of the behavioral context and performance on motor cortical population activity during movement preparation and execution. PMID:20884766

  1. Taste-Guided Decisions Differentially Engage Neuronal Ensembles across Gustatory Cortices

    PubMed Central

    MacDonald, Christopher J.; Meck, Warren H.; Simon, Sidney A.; Nicolelis, Miguel A.L.

    2009-01-01

    Much remains to be understood about the differential contributions from primary and secondary sensory cortices to sensory guided decision making. To address this issue we simultaneously recorded activity from neuronal ensembles in primary (gustatory cortex – GC) and secondary gustatory (orbitofrontal cortex – OFC) cortices while rats made a taste-guided decision between two response alternatives. We found that before animals commenced a response guided by a tastant cue, GC ensembles contained more information than OFC about the response alternative about to be selected. Thereafter, while the animal’s response was underway the response selective information in ensembles from both regions increased, albeit to a greater degree in OFC. In GC, this increase depends on a representation of the taste cue guiding the animal‘s response. The increase in the OFC also depends on the taste cue guiding and other features of the response such as its spatiomotor properties and the behavioral context under which it is executed. Each of these latter features is encoded by different ensembles of OFC neurons that are recruited at specific times throughout the response selection process. These results indicate that during a taste-guided decision task both primary and secondary gustatory cortices dynamically encode different types of information. PMID:19741134

  2. Physiological approaches to understanding molecular actions on dorsolateral prefrontal cortical neurons underlying higher cognitive processing.

    PubMed

    Wang, Min; Arnsten, Amy F T

    2015-11-18

    Revealing how molecular mechanisms influence higher brain circuits in primates will be essential for understanding how genetic insults lead to increased risk of cognitive disorders. Traditionally, modulatory influences on higher cortical circuits have been examined using lesion techniques, where a brain region is depleted of a particular transmitter to determine how its loss impacts cognitive function. For example, depletion of catecholamines or acetylcholine from the dorsolateral prefrontal cortex produces striking deficits in working memory abilities. More directed techniques have utilized direct infusions of drug into a specific cortical site to try to circumvent compensatory changes that are common following transmitter depletion. The effects of drug on neuronal firing patterns are often studied using iontophoresis, where a minute amount of drug is moved into the brain using a tiny electrical current, thus minimizing the fluid flow that generally disrupts neuronal recordings. All of these approaches can be compared to systemic drug administration, which remains a key arena for the development of effective therapeutics for human cognitive disorders. Most recently, viral techniques are being developed to be able to manipulate proteins for which there is no developed pharmacology, and to allow optogenetic manipulations in primate cortex. As the association cortices greatly expand in brain evolution, research in nonhuman primates is particularly important for understanding the modulatory regulation of our highest order cognitive operations. PMID:26646567

  3. Cerebral cortical activity associated with non-experts' most accurate motor performance.

    PubMed

    Dyke, Ford; Godwin, Maurice M; Goel, Paras; Rehm, Jared; Rietschel, Jeremy C; Hunt, Carly A; Miller, Matthew W

    2014-10-01

    This study's specific aim was to determine if non-experts' most accurate motor performance is associated with verbal-analytic- and working memory-related cerebral cortical activity during motor preparation. To assess this, EEG was recorded from non-expert golfers executing putts; EEG spectral power and coherence were calculated for the epoch preceding putt execution; and spectral power and coherence for the five most accurate putts were contrasted with that for the five least accurate. Results revealed marked power in the theta frequency bandwidth at all cerebral cortical regions for the most accurate putts relative to the least accurate, and considerable power in the low-beta frequency bandwidth at the left temporal region for the most accurate compared to the least. As theta power is associated with working memory and low-beta power at the left temporal region with verbal analysis, results suggest non-experts' most accurate motor performance is associated with verbal-analytic- and working memory-related cerebral cortical activity during motor preparation. PMID:25058623

  4. Physiological approaches to understanding molecular actions on dorsolateral prefrontal cortical neurons underlying higher cognitive processing

    PubMed Central

    WANG, Min; ARNSTEN, Amy F.T.

    2015-01-01

    Revealing how molecular mechanisms influence higher brain circuits in primates will be essential for understanding how genetic insults lead to increased risk of cognitive disorders. Traditionally, modulatory influences on higher cortical circuits have been examined using lesion techniques, where a brain region is depleted of a particular transmitter to determine how its loss impacts cognitive function. For example, depletion of catecholamines or acetylcholine from the dorsolateral prefrontal cortex produces striking deficits in working memory abilities. More directed techniques have utilized direct infusions of drug into a specific cortical site to try to circumvent compensatory changes that are common following transmitter depletion. The effects of drug on neuronal firing patterns are often studied using iontophoresis, where a minute amount of drug is moved into the brain using a tiny electrical current, thus minimizing the fluid flow that generally disrupts neuronal recordings. All of these approaches can be compared to systemic drug administration, which remains a key arena for the development of effective therapeutics for human cognitive disorders. Most recently, viral techniques are being developed to be able to manipulate proteins for which there is no developed pharmacology, and to allow optogenetic manipulations in primate cortex. As the association cortices greatly expand in brain evolution, research in nonhuman primates is particularly important for understanding the modulatory regulation of our highest order cognitive operations. PMID:26646567

  5. Cortical plasticity in patients with Parkinson's disease a window for therapeutic non-invasive neuromodulation.

    PubMed

    Quartarone, Angelo; Rizzo, Vincenzo; Terranova, Carmen; Bruschetta, Daniele; Milardi, Demetrio; Girlanda, Paolo; Ghilardi, Maria Felice

    2014-12-01

    Several evidences in animal models have consistently an alteration of cortico-striatal plasticity, which is related to the degeneration of the substantia nigra. An alteration of plasticity have also been reported in humans by recording evoked field potentials in the substantia nigra pars reticulata of PD patients undergoing subthalamic nucleus (STN) stimulation where high-frequency (HF) in the OFF state did not induce a lasting change in field potential amplitude in the substantia nigra. In addition protocols of non-invasive brain stimulation, such as paired associative stimulation (PAS) and theta-burst stimulation (TBS), can be used to investigate cortical plasticity of the human primary motor cortex. Despite data reported in literature are apparently controversial with some studies showing a reduced or increased or even normal LTP and LTD like plasticity, recent evidences suggest the hypothesis that these different pat- terns of cortical plasticity likely depend on the stage of the disease and on the concomitant administration of L-DOPA. The current review will provide an up-to-date of these issues on cortical plasticity in PD discussing the clinical implications in rehabilitation. In addition in the last section we will review the state of art of non invasive neuro- modulation as adjuvant treatment in the advanced stage of the disease. PMID:25987183

  6. Suppression of beta oscillations in the subthalamic nucleus following cortical stimulation in humans

    PubMed Central

    Doyle Gaynor, L M F; Kühn, A A; Dileone, M; Litvak, V; Eusebio, A; Pogosyan, A; Androulidakis, A G; Tisch, S; Limousin, P; Insola, A; Mazzone, P; Di Lazzaro, V; Brown, P

    2008-01-01

    It is unclear how subthalamic nucleus activity is modulated by the cerebral cortex. Here we investigate the effect of transcranial magnetic stimulation (TMS) of the cortex on oscillatory subthalamic local field potential activity in the 8–35 Hz (alpha/beta) band, as exaggerated synchronization in this band is implicated in the pathophysiology of parkinsonism. We studied nine patients with Parkinson’s disease (PD) to test whether cortical stimulation can modulate synchronized oscillations in the human subthalamic nucleus. With patients at rest, single-pulse TMS was delivered every 5 s over each primary motor area and supplementary motor area at intensities of 85–115% resting motor threshold. Subthalamic local field potentials were recorded from deep brain stimulation electrodes implanted into this nucleus for the treatment of PD. Motor cortical stimulation suppressed beta activity in the subthalamic nucleus from ∼0.2 to 0.6 s after TMS (repeated measures anova; main effect of time, P<0.01; main effect of side, P=0.03), regardless of intensity. TMS over the supplementary motor area also reduced subthalamic beta activity at 95% (P=0.05) and 115% resting motor threshold (P=0.01). The oscillatory activity decreased to 80 ± 26% of baseline (averaged across sites and stimulation intensities). Suppression with subthreshold stimuli confirmed that these changes were centrally driven and not due to peripheral afference. The results may have implications for mechanisms underlying the reported therapeutic benefits of cortical stimulation. PMID:18657185

  7. Cortical Low-Frequency Power and Progressive Phase Synchrony Precede Successful Memory Encoding

    PubMed Central

    Haque, Rafi U.; Wittig, John H.; Damera, Srikanth R.; Inati, Sara K.

    2015-01-01

    Neural activity preceding an event can influence subsequent memory formation, yet the precise cortical dynamics underlying this activity and the associated cognitive states remain unknown. We investigate these questions here by examining intracranial EEG recordings as 28 participants with electrodes placed for seizure monitoring participated in a verbal paired-associates memory task. We found that, preceding successfully remembered word pairs, an orientation cue triggered a low-frequency 2–4 Hz phase reset in the right temporoparietal junction with concurrent increases in low-frequency power across cortical regions that included the prefrontal cortex and left temporal lobe. Regions that exhibited a significant increase in 2–4 Hz power were functionally bound together through progressive low-frequency 2–4 Hz phase synchrony. Our data suggest that the interaction between power and phase synchrony reflects the engagement of attentional networks that in large part determine the extent to which memories are successfully encoded. SIGNIFICANCE STATEMENT Here we investigate the spatiotemporal cortical dynamics that precede successful memory encoding. Using intracranial EEG, we observed significant changes in oscillatory power, intertrial phase consistency, and pairwise phase synchrony that predict successful encoding. Our data suggest that the interaction between power and phase synchrony reflects the engagement of attentional networks that in large part determine the extent to which memories are successfully encoded. PMID:26446212

  8. Resting state cortical rhythms in athletes: a high-resolution EEG study.

    PubMed

    Babiloni, Claudio; Marzano, Nicola; Iacoboni, Marco; Infarinato, Francesco; Aschieri, Pierluigi; Buffo, Paola; Cibelli, Giuseppe; Soricelli, Andrea; Eusebi, Fabrizio; Del Percio, Claudio

    2010-01-15

    The present electroencephalographic (EEG) study tested the working hypothesis that the amplitude of resting state cortical EEG rhythms (especially alpha, 8-12 Hz) was higher in elite athletes compared with amateur athletes and non-athletes, as a reflection of the efficiency of underlying back-ground neural synchronization mechanisms. Eyes closed resting state EEG data were recorded in 16 elite karate athletes, 20 amateur karate athletes, and 25 non-athletes. The EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by low-resolution brain electromagnetic tomography (LORETA). Statistical results showed that the amplitude of parietal and occipital alpha 1 sources was significantly higher in the elite karate athletes than in the non-athletes and karate amateur athletes. Similar results were observed in parietal and occipital delta sources as well as in occipital theta sources. Finally, a control confirmatory experiment showed that the amplitude of parietal and occipital delta and alpha 1 sources was stronger in 8 elite rhythmic gymnasts compared with 14 non-athletes. These results supported the hypothesis that cortical neural synchronization at the basis of eyes-closed resting state EEG rhythms is enhanced in elite athletes than in control subjects. PMID:19879337

  9. Decoupling of Sleep-Dependent Cortical and Hippocampal Interactions in a Neurodevelopmental Model of Schizophrenia

    PubMed Central

    Phillips, Keith G.; Bartsch, Ullrich; McCarthy, Andrew P.; Edgar, Dale M.; Tricklebank, Mark D.; Wafford, Keith A.; Jones, Matt W.

    2012-01-01

    Summary Rhythmic neural network activity patterns are defining features of sleep, but interdependencies between limbic and cortical oscillations at different frequencies and their functional roles have not been fully resolved. This is particularly important given evidence linking abnormal sleep architecture and memory consolidation in psychiatric diseases. Using EEG, local field potential (LFP), and unit recordings in rats, we show that anteroposterior propagation of neocortical slow-waves coordinates timing of hippocampal ripples and prefrontal cortical spindles during NREM sleep. This coordination is selectively disrupted in a rat neurodevelopmental model of schizophrenia: fragmented NREM sleep and impaired slow-wave propagation in the model culminate in deficient ripple-spindle coordination and disrupted spike timing, potentially as a consequence of interneuronal abnormalities reflected by reduced parvalbumin expression. These data further define the interrelationships among slow-wave, spindle, and ripple events, indicating that sleep disturbances may be associated with state-dependent decoupling of hippocampal and cortical circuits in psychiatric diseases. PMID:23141065

  10. The Stimulus Selectivity and Connectivity of Layer Six Principal Cells Reveals Cortical Microcircuits Underlying Visual Processing

    PubMed Central

    Vélez-Fort, Mateo; Rousseau, Charly V.; Niedworok, Christian J.; Wickersham, Ian R.; Rancz, Ede A.; Brown, Alexander P.Y.; Strom, Molly; Margrie, Troy W.

    2014-01-01

    Summary Sensory computations performed in the neocortex involve layer six (L6) cortico-cortical (CC) and cortico-thalamic (CT) signaling pathways. Developing an understanding of the physiological role of these circuits requires dissection of the functional specificity and connectivity of the underlying individual projection neurons. By combining whole-cell recording from identified L6 principal cells in the mouse primary visual cortex (V1) with modified rabies virus-based input mapping, we have determined the sensory response properties and upstream monosynaptic connectivity of cells mediating the CC or CT pathway. We show that CC-projecting cells encompass a broad spectrum of selectivity to stimulus orientation and are predominantly innervated by deep layer V1 neurons. In contrast, CT-projecting cells are ultrasparse firing, exquisitely tuned to orientation and direction information, and receive long-range input from higher cortical areas. This segregation in function and connectivity indicates that L6 microcircuits route specific contextual and stimulus-related information within and outside the cortical network. PMID:25175879

  11. Modulation of Cortical Inhibitory Circuits after Cathodal Transcranial Direct Current Stimulation over the Primary Motor Cortex

    PubMed Central

    Sasaki, Ryoki; Miyaguchi, Shota; Kotan, Shinichi; Kojima, Sho; Kirimoto, Hikari; Onishi, Hideaki

    2016-01-01

    Here, we aimed to evaluate whether cathodal transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) and primary somatosensory cortex (S1) can modulate cortical inhibitory circuits. Sixteen healthy subjects participated in this study. Cathodal tDCS was positioned over the left M1 (M1 cathodal) or left S1 (S1 cathodal) with an intensity of 1 mA for 10 min. Sham tDCS was applied for 10 min over the left M1 (sham). Motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) were recorded from the right abductor pollicis brevis (APB) muscle before the intervention (pre) and 10 and 30 min after the intervention (post 1 and post 2, respectively). Cortical inhibitory circuits were evaluated using short-interval intracortical inhibition (SICI) and short-latency afferent inhibition (SAI). M1 cathodal decreased single-pulse MEP amplitudes at post 1 and decreased SAI at post 1 and post 2; however, SICI did not exhibit any change. S1 cathodal and sham did not show any changes in MEP amplitudes at any of the three time points. These results demonstrated that cathodal tDCS over the M1 not only decreases the M1 excitability but also affects the cortical inhibitory circuits related to SAI. PMID:26869909

  12. Impact of Acetazolamide and CPAP on Cortical Activity in Obstructive Sleep Apnea Patients

    PubMed Central

    Stadelmann, Katrin; Latshang, Tsogyal D.; Nussbaumer-Ochsner, Yvonne; Tarokh, Leila; Ulrich, Silvia; Kohler, Malcolm; Bloch, Konrad E.; Achermann, Peter

    2014-01-01

    Study Objectives 1) To investigate the impact of acetazolamide, a drug commonly prescribed for altitude sickness, on cortical oscillations in patients with obstructive sleep apnea syndrome (OSAS). 2) To examine alterations in the sleep EEG after short-term discontinuation of continuous positive airway pressure (CPAP) therapy. Design Data from two double-blind, placebo-controlled randomized cross-over design studies were analyzed. Setting Polysomnographic recordings in sleep laboratory at 490 m and at moderate altitudes in the Swiss Alps: 1630 or 1860 m and 2590 m. Patients Study 1: 39 OSAS patients. Study 2: 41 OSAS patients. Interventions Study 1: OSAS patients withdrawn from treatment with CPAP. Study 2: OSAS patients treated with autoCPAP. Treatment with acetazolamide (500–750 mg) or placebo at moderate altitudes. Measurements and Results An evening dose of 500 mg acetazolamide reduced slow-wave activity (SWA; approximately 10%) and increased spindle activity (approximately 10%) during non-REM sleep. In addition, alpha activity during wake after lights out was increased. An evening dose of 250 mg did not affect these cortical oscillations. Discontinuation of CPAP therapy revealed a reduction in SWA (5–10%) and increase in beta activity (approximately 25%). Conclusions The higher evening dose of 500 mg acetazolamide showed the “spectral fingerprint” of Benzodiazepines, while 250 mg acetazolamide had no impact on cortical oscillations. However, both doses had beneficial effects on oxygen saturation and sleep quality. PMID:24710341

  13. Monitoring transcranial direct current stimulation induced changes in cortical excitability during the serial reaction time task.

    PubMed

    Ambrus, Géza Gergely; Chaieb, Leila; Stilling, Roman; Rothkegel, Holger; Antal, Andrea; Paulus, Walter

    2016-03-11

    The measurement of the motor evoked potential (MEP) amplitudes using single pulse transcranial magnetic stimulation (TMS) is a common method to observe changes in motor cortical excitability. The level of cortical excitability has been shown to change during motor learning. Conversely, motor learning can be improved by using anodal transcranial direct current stimulation (tDCS). In the present study, we aimed to monitor cortical excitability changes during an implicit motor learning paradigm, a version of the serial reaction time task (SRTT). Responses from the first dorsal interosseous (FDI) and forearm flexor (FLEX) muscles were recorded before, during and after the performance of the SRTT. Online measurements were combined with anodal, cathodal or sham tDCS for the duration of the SRTT. Negative correlations between the amplitude of online FDI MEPs and SRTT reaction times (RTs) were observed across the learning blocks in the cathodal condition (higher average MEP amplitudes associated with lower RTs) but no significant differences in the anodal and sham conditions. tDCS did not have an impact on SRTT performance, as would be predicted based on previous studies. The offline before-after SRTT MEP amplitudes showed an increase after anodal and a tendency to decrease after cathodal stimulation, but these changes were not significant. The combination of different interventions during tDCS might result in reduced efficacy of the stimulation that in future studies need further attention. PMID:26826607

  14. Cortical Dependence of Whisker Responses in Posterior Medial Thalamus In Vivo

    PubMed Central

    Mease, Rebecca A.; Sumser, Anton; Sakmann, Bert; Groh, Alexander

    2016-01-01

    Cortical layer 5B (L5B) thick-tufted pyramidal neurons have reliable responses to whisker stimulation in anesthetized rodents. These cells drive a corticothalamic pathway that evokes spikes in thalamic posterior medial nucleus (POm). While a subset of POm has been shown to integrate both cortical L5B and paralemniscal signals, the majority of POm neurons are suggested to receive driving input from L5B only. Here, we test this possibility by investigating the origin of whisker-evoked responses in POm and specifically the contribution of the L5B-POm pathway. We compare L5B spiking with POm spiking and subthreshold responses to whisker deflections in urethane anesthetized mice. We find that a subset of recorded POm neurons shows early (<50 ms) spike responses and early large EPSPs. In these neurons, the early large EPSPs matched L5B input criteria, were blocked by cortical inhibition, and also interacted with spontaneous Up state coupled large EPSPs. This result supports the view of POm subdivisions, one of which receives whisker signals predominantly via L5B neurons. PMID:27230219

  15. Changes in basal ganglia processing of cortical input following magnetic stimulation in Parkinsonism.

    PubMed

    Tischler, Hadass; Moran, Anan; Belelovsky, Katya; Bronfeld, Maya; Korngreen, Alon; Bar-Gad, Izhar

    2012-12-01

    Parkinsonism is associated with major changes in neuronal activity throughout the cortico-basal ganglia loop. Current measures quantify changes in baseline neuronal and network activity but do not capture alterations in information propagation throughout the system. Here, we applied a novel non-invasive magnetic stimulation approach using a custom-made mini-coil that enabled us to study transmission of neuronal activity throughout the cortico-basal ganglia loop in both normal and parkinsonian primates. By magnetically perturbing cortical activity while simultaneously recording neuronal responses along the cortico-basal ganglia loop, we were able to directly investigate modifications in descending cortical activity transmission. We found that in both the normal and parkinsonian states, cortical neurons displayed similar multi-phase firing rate modulations in response to magnetic stimulation. However, in the basal ganglia, large synaptically driven stereotypic neuronal modulation was present in the parkinsonian state that was mostly absent in the normal state. The stimulation-induced neuronal activity pattern highlights the change in information propagation along the cortico-basal ganglia loop. Our findings thus point to the role of abnormal dynamic activity transmission rather than changes in baseline activity as a major component in parkinsonian pathophysiology. Moreover, our results hint that the application of transcranial magnetic stimulation (TMS) in human patients of different disorders may result in different neuronal effects than the one induced in normal subjects. PMID:22885186

  16. Spatiotemporal memory is an intrinsic property of networks of dissociated cortical neurons.

    PubMed

    Ju, Han; Dranias, Mark R; Banumurthy, Gokulakrishna; VanDongen, Antonius M J

    2015-03-01

    The ability to process complex spatiotemporal information is a fundamental process underlying the behavior of all higher organisms. However, how the brain processes information in the temporal domain remains incompletely understood. We have explored the spatiotemporal information-processing capability of networks formed from dissociated rat E18 cortical neurons growing in culture. By combining optogenetics with microelectrode array recording, we show that these randomly organized cortical microcircuits are able to process complex spatiotemporal information, allowing the identification of a large number of temporal sequences and classification of musical styles. These experiments uncovered spatiotemporal memory processes lasting several seconds. Neural network simulations indicated that both short-term synaptic plasticity and recurrent connections are required for the emergence of this capability. Interestingly, NMDA receptor function is not a requisite for these short-term spatiotemporal memory processes. Indeed, blocking the NMDA receptor with the antagonist APV significantly improved the temporal processing ability of the networks, by reducing spontaneously occurring network bursts. These highly synchronized events have disastrous effects on spatiotemporal information processing, by transiently erasing short-term memory. These results show that the ability to process and integrate complex spatiotemporal information is an intrinsic property of generic cortical networks that does not require specifically designed circuits. PMID:25740531

  17. Lesions in posterior parietal area 5 in monkeys result in rapid behavioral and cortical plasticity

    PubMed Central

    Padberg, Jeffrey; Recanzone, Gregg; Engle, James; Cooke, Dylan; Goldring, Adam; Krubitzer, Leah

    2012-01-01

    We examined the effects of focal lesions of posterior parietal area 5 in macaque monkeys on bimanual behavior performed with and without visual guidance. The animals were trained on two reaching tasks and one tactile texture discrimination task. Task 1 simply involved reaching toward and grasping a reward from one of five well positions. Task 2 required the monkey to use both hands simultaneously to obtain a reward. The tactile texture discrimination task required the monkey to signal the roughness of a passively delivered texture using its jaw. Following lesions to area 5, the monkeys showed a decrease in hand use for tasks 1 and 2 and an inability to perform task 2 in specific locations in visual space. These deficits recovered within several days. No deficits were observed in the tactile texture discrimination task, or in an analgesic control monkey. Electrophysiological recordings made just prior to the lesion, immediately following the lesion, and 2 months following the lesion demonstrated that cortical areas just rostral to the lesioned area 5, areas 1 and 2, were topographically reorganized and that receptive fields for neurons in these fields changed location on the body surface. These cortical map changes are correlative and may, in part, contribute to the rapid behavioral recovery observed. The mechanism for such rapid changes may be the unmasking of existing divergent and convergent thalamocortical connections that are part of the normal cortical circuitry. PMID:20881111

  18. Movement-related parameters modulate cortical activity during imaginary isometric plantar-flexions.

    PubMed

    do Nascimento, Omar Feix; Nielsen, Kim Dremstrup; Voigt, Michael

    2006-05-01

    A multitude of studies have demonstrated a clear activation of the motor cortex during imagination of various motor tasks; however, it is still unclear if movement-related parameters (movement direction, range of motion, speed, force level and rate of force development) specifically modulate cortical activation as they do during the execution of actual motor tasks. Accordingly, this study examined whether the rate of torque development (RTD) and/or the torque amplitude modulates cortical potentials generated during imaginary motor tasks. Fifteen subjects imagined four different left-sided isometric plantar-flexion tasks, while EEG and EMG recordings were being performed. The averaged EEG activity was analyzed in terms of movement-related potentials (MRPs), consisting of readiness potential (RP), motor potential (MP) and movement-monitoring potential (MMP). It was demonstrated that RTD and torque amplitude indeed modulate cortical activity during imaginary motor tasks. Information concerning movement-related parameters for imaginary plantar-flexion tasks seems to be encoded in the supplementary motor area (SMA) and the primary motor cortex (M1). A comparison between MRPs of imaginary and actual motor tasks revealed that early MRPs were morphologically similar, but differed significantly in amplitude. One of the possible suggestions to explain such a difference may be an "abortion" of ongoing motor programs. PMID:16320044

  19. Cortical Dependence of Whisker Responses in Posterior Medial Thalamus In Vivo.

    PubMed

    Mease, Rebecca A; Sumser, Anton; Sakmann, Bert; Groh, Alexander

    2016-08-01

    Cortical layer 5B (L5B) thick-tufted pyramidal neurons have reliable responses to whisker stimulation in anesthetized rodents. These cells drive a corticothalamic pathway that evokes spikes in thalamic posterior medial nucleus (POm). While a subset of POm has been shown to integrate both cortical L5B and paralemniscal signals, the majority of POm neurons are suggested to receive driving input from L5B only. Here, we test this possibility by investigating the origin of whisker-evoked responses in POm and specifically the contribution of the L5B-POm pathway. We compare L5B spiking with POm spiking and subthreshold responses to whisker deflections in urethane anesthetized mice. We find that a subset of recorded POm neurons shows early (<50 ms) spike responses and early large EPSPs. In these neurons, the early large EPSPs matched L5B input criteria, were blocked by cortical inhibition, and also interacted with spontaneous Up state coupled large EPSPs. This result supports the view of POm subdivisions, one of which receives whisker signals predominantly via L5B neurons. PMID:27230219

  20. Longitudinal Evaluation of Residual Cortical and Subcortical Motor Evoked Potentials in Spinal Cord Injured Rats.

    PubMed

    Redondo-Castro, Elena; Navarro, Xavier; García-Alías, Guillermo

    2016-05-15

    We have applied transcranial electrical stimulation to rats with spinal cord injury and selectively tested the motor evoked potentials (MEPs) conveyed by descending motor pathways with cortical and subcortical origin. MEPs were elicited by electrical stimulation to the brain and recorded on the tibialis anterior muscles. Stimulation parameters were characterized and changes in MEP responses tested in uninjured rats, in rats with mild or moderate contusion, and in animals with complete transection of the spinal cord. All injuries were located at the T8 vertebral level. Two peaks, termed N1 and N2, were obtained when changing from single pulse stimulation to trains of 9 pulses at 9 Hz. Selective injuries to the brain or spinal cord funiculi evidenced the subcortical origin of N1 and the cortical origin of N2. Animals with mild contusion showed small behavioral deficits and abolished N1 but maintained small amplitude N2 MEPs. Substantial motor deficits developed in rats with moderate contusion, and these rats had completely eliminated N1 and N2 MEPs. Animals with complete cord transection had abolished N1 and N2 and showed severe impairment of locomotion. The results indicate the reliability of MEP testing to longitudinally evaluate over time the degree of impairment of cortical and subcortical spinal pathways after spinal cord injuries of different severity. PMID:26560177

  1. Imaging cortical dynamics of language processing with the event-related optical signal.

    PubMed

    Tse, Chun-Yu; Lee, Chia-Lin; Sullivan, Jason; Garnsey, Susan M; Dell, Gary S; Fabiani, Monica; Gratton, Gabriele

    2007-10-23

    Language processing involves the rapid interaction of multiple brain regions. The study of its neurophysiological bases would therefore benefit from neuroimaging techniques combining both good spatial and good temporal resolution. Here we use the event-related optical signal (EROS), a recently developed imaging method, to reveal rapid interactions between left superior/middle temporal cortices (S/MTC) and inferior frontal cortices (IFC) during the processing of semantically or syntactically anomalous sentences. Participants were presented with sentences of these types intermixed with nonanomalous control sentences and were required to judge their acceptability. ERPs were recorded simultaneously with EROS and showed the typical activities that are elicited when processing anomalous stimuli: the N400 and the P600 for semantic and syntactic anomalies, respectively. The EROS response to semantically anomalous words showed increased activity in the S/MTC (corresponding in time with the N400), followed by IFC activity. Syntactically anomalous words evoked a similar sequence, with a temporal-lobe EROS response (corresponding in time with the P600), followed by frontal activity. However, the S/MTC activity corresponding to a semantic anomaly was more ventral than that corresponding to a syntactic anomaly. These data suggest that activation related to anomaly processing in sentences proceeds from temporal to frontal brain regions for both semantic and syntactic anomalies. This first EROS study investigating language processing shows that EROS can be used to image rapid interactions across cortical areas. PMID:17942677

  2. Imaging cortical dynamics of language processing with the event-related optical signal

    PubMed Central

    Tse, Chun-Yu; Lee, Chia-Lin; Sullivan, Jason; Garnsey, Susan M.; Dell, Gary S.; Fabiani, Monica; Gratton, Gabriele

    2007-01-01

    Language processing involves the rapid interaction of multiple brain regions. The study of its neurophysiological bases would therefore benefit from neuroimaging techniques combining both good spatial and good temporal resolution. Here we use the event-related optical signal (EROS), a recently developed imaging method, to reveal rapid interactions between left superior/middle temporal cortices (S/MTC) and inferior frontal cortices (IFC) during the processing of semantically or syntactically anomalous sentences. Participants were presented with sentences of these types intermixed with nonanomalous control sentences and were required to judge their acceptability. ERPs were recorded simultaneously with EROS and showed the typical activities that are elicited when processing anomalous stimuli: the N400 and the P600 for semantic and syntactic anomalies, respectively. The EROS response to semantically anomalous words showed increased activity in the S/MTC (corresponding in time with the N400), followed by IFC activity. Syntactically anomalous words evoked a similar sequence, with a temporal-lobe EROS response (corresponding in time with the P600), followed by frontal activity. However, the S/MTC activity corresponding to a semantic anomaly was more ventral than that corresponding to a syntactic anomaly. These data suggest that activation related to anomaly processing in sentences proceeds from temporal to frontal brain regions for both semantic and syntactic anomalies. This first EROS study investigating language processing shows that EROS can be used to image rapid interactions across cortical areas. PMID:17942677

  3. Enhancement of synaptic transmission induced by BDNF in cultured cortical neurons

    NASA Astrophysics Data System (ADS)

    He, Jun; Gong, Hui; Zeng, Shaoqun; Li, Yanling; Luo, Qingming

    2005-03-01

    Brain-derived neurotrophic factor (BDNF), like other neurotrophins, has long-term effects on neuronal survival and differentiation; furthermore, BDNF has been reported to exert an acute potentiation of synaptic activity and are critically involved in long-term potentiation (LTP). We found that BDNF rapidly induced potentiation of synaptic activity and an increase in the intracellular Ca2+ concentration in cultured cortical neurons. Within minutes of BDNF application to cultured cortical neurons, spontaneous firing rate was dramatically increased as were the frequency and amplitude of excitatory spontaneous postsynaptic currents (EPSCs). Fura-2 recordings showed that BDNF acutely elicited an increase in intracellular calcium concentration ([Ca2+]c). This effect was partially dependent on [Ca2+]o; The BDNF-induced increase in [Ca2+]c can not be completely blocked by Ca2+-free solution. It was completely blocked by K252a and partially blocked by Cd2+ and TTX. The results demonstrate that BDNF can enhances synaptic transmission and that this effect is accompanied by a rise in [Ca2+]c that requires two route: the release of Ca2+ from intracellular calcium stores and influx of extracellular Ca2+ through voltage-dependent Ca2+ channels in cultured cortical neurons.

  4. The 40-Hz auditory steady-state response: a selective biomarker for cortical NMDA function.

    PubMed

    Sivarao, Digavalli V

    2015-05-01

    When subjected to a phasic input, sensory cortical neurons display a remarkable ability to entrain faithfully to the driving stimuli. The entrainment to rhythmic sound stimuli is often referred to as the auditory steady-state response (ASSR) and can be captured using noninvasive techniques, such as scalp-recorded electroencephalography (EEG). An ASSR to a driving frequency of approximately 40 Hz is particularly interesting in that it shows, in relative terms, maximal power, synchrony, and synaptic activity. Moreover, the 40-Hz ASSR has been consistently found to be abnormal in schizophrenia patients across multiple studies. The nature of the reported abnormality has been less consistent; while most studies report a deficit in entrainment, several studies have reported increased signal power, particularly when there are concurrent positive symptoms, such as auditory hallucinations. However, the neuropharmacological basis for the 40-Hz ASSR, as well as its dysfunction in schizophrenia, has been unclear until recently. On the basis of several recent reports, it is argued that the 40-Hz ASSR represents a specific marker for cortical NMDA transmission. If confirmed, the 40-Hz ASSR may be a simple and easy-to-access pharmacodynamic biomarker for testing the integrity of cortical NMDA neurotransmission that is robustly translational across species. PMID:25809615

  5. Neuromagnetic fields reveal cortical plasticity when learning an auditory discrimination task.

    PubMed

    Cansino, S; Williamson, S J

    1997-08-01

    Auditory evoked neuromagnetic fields of the primary and association auditory cortices were recorded while subjects learned to discriminate small differences in frequency and intensity between two consecutive tones. When discrimination was no better than chance, evoked field patterns across the scalp manifested no significant differences between correct and incorrect responses. However, when performance was correct on at least 75% of the trials, the spatial pattern of magnetic field differed significantly between correct and incorrect responses during the first 70 ms following the onset of the second tone. In this respect, the magnetic field pattern predicted when the subject would make an incorrect judgment more than 100 ms prior to indicating the judgment by a button press. One subject improved discrimination for much smaller differences between stimuli after 200 h of training. Evidence of cortical plasticity with improved discrimination is provided by an accompanying decrease of the relative magnetic field amplitude of the 100 ms response components in the primary and association auditory cortices. PMID:9295193

  6. Assessment of sensorimotor cortical representation asymmetries and motor skills in violin players.

    PubMed

    Schwenkreis, Peter; El Tom, Susan; Ragert, Patrick; Pleger, Burkhard; Tegenthoff, Martin; Dinse, Hubert R

    2007-12-01

    As a model for use-dependent plasticity, the brains of professional musicians have been extensively studied to examine structural and functional adaptation to unique requirements of skilled performance. Here we provide a combination of data on motor performance and hand representation in the primary motor and somatosensory cortex of professional violin players, with the aim of assessing possible behavioural consequences of sensorimotor cortical asymmetries. We studied 15 healthy right-handed professional violin players and 35 healthy nonmusician controls. Motor and somatosensory cortex asymmetry was assessed by recording the motor output map after transcranial magnetic stimulation from a small hand muscle, and by dipole source localization of somatosensory evoked potentials after electrical stimulation of the median and ulnar nerves. Motor performance was examined using a series of standardized motor tasks covering different aspects of hand function. Violin players showed a significant right-larger-than-left asymmetry of the motor and somatosensory cortex, whereas nonmusician controls showed no significant interhemispheric difference. The amount of asymmetry in the motor and somatosensory cortices of musicians was significantly correlated. At the behavioural level, motor performance did not significantly differ between musicians and nonmusicians. The results support a use-dependent enlargement of the left hand representation in the sensorimotor cortex of violin players. However, these cortical asymmetries were not paralleled by accompanying altered asymmetries at a behavioural level, suggesting that the reorganisation might be task-specific and does not lead to improved motor abilities in general. PMID:18028115

  7. Dynamics of electrocorticographic (ECoG) activity in human temporal and frontal cortical areas during music listening.

    PubMed

    Potes, Cristhian; Gunduz, Aysegul; Brunner, Peter; Schalk, Gerwin

    2012-07-16

    Previous studies demonstrated that brain signals encode information about specific features of simple auditory stimuli or of general aspects of natural auditory stimuli. How brain signals represent the time course of specific features in natural auditory stimuli is not well understood. In this study, we show in eight human subjects that signals recorded from the surface of the brain (electrocorticography (ECoG)) encode information about the sound intensity of music. ECoG activity in the high gamma band recorded from the posterior part of the superior temporal gyrus as well as from an isolated area in the precentral gyrus was observed to be highly correlated with the sound intensity of music. These results not only confirm the role of auditory cortices in auditory processing but also point to an important role of premotor and motor cortices. They also encourage the use of ECoG activity to study more complex acoustic features of simple or natural auditory stimuli. PMID:22537600

  8. Cortical Bases of Speech Perception: Evidence from Functional Lesion Studies

    ERIC Educational Resources Information Center

    Boatman, Dana

    2004-01-01

    Functional lesion studies have yielded new information about the cortical organization of speech perception in the human brain. We will review a number of recent findings, focusing on studies of speech perception that use the techniques of electrocortical mapping by cortical stimulation and hemispheric anesthetization by intracarotid amobarbital.…

  9. Imaging of an adrenal cortical carcinoma and its skeletal metastasis

    SciTech Connect

    Drane, W.E.; Graham, M.M.; Nelp, W.B.

    1983-08-01

    Though the typical scintigraphic appearance in adrenal cortical carcinoma is bilateral nonvisualization of the adrenal glands, a case with simultaneous visualization of both an adrenal cortical carcinoma and its skeletal metastasis using 6-..beta..-(/sup 131/I)iodomethyl-19-norcholesterol is reported.

  10. Imaging of an adrenal cortical carcinoma and its skeletal metastasis

    SciTech Connect

    Drane, W.E.; Graham, M.M.; Nelp, W.B.

    1983-08-01

    Though the typical scintigraphic appearance in adrenal cortical carcinoma is bilateral nonvisualization of the adrenal glands, we report a case with simultaneous visualization of both an adrenal cortical carcinoma and its skeletal metastasis using 6-beta-(/sup 131/I)iodomethyl-19-norcholesterol.

  11. Increased temporolimbic cortical folding complexity in temporal lobe epilepsy

    PubMed Central

    Voets, N.L.; Bernhardt, B.C.; Kim, H.; Yoon, U.

    2011-01-01

    Objective: Converging evidence suggests that abnormalities of brain development may play a role in the pathogenesis of temporal lobe epilepsy (TLE). As sulco-gyral patterns are thought to be a footprint of cortical development, we set out to quantitatively map folding complexity across the neocortex in TLE. Additionally, we tested whether there was a relationship between cortical complexity and features of hippocampal maldevelopment, commonly referred to as malrotation. Methods: To quantify folding complexity, we obtained whole-brain surface-based measures of absolute mean cortical curvature from MRI scans acquired in 43 drug-resistant patients with TLE with unilateral hippocampal atrophy, and 40 age- and sex-matched healthy controls. In patients, we correlated changes in cortical curvature with 3-dimensional measures of hippocampal positioning. Results: We found increased folding complexity in the temporolimbic cortices encompassing parahippocampal, temporopolar, insular, and fronto-opercular regions. Increased complexity was observed ipsilateral to the seizure focus in patients with left TLE (LTLE), whereas these changes were bilateral in patients with right TLE (RTLE). In both TLE groups, increased temporolimbic complexity was associated with increased hippocampal malrotation. We found tendencies for increased complexity in bilateral posterior temporal cortices in LTLE and contralateral parahippocampal cortices in RTLE to be predictive of unfavorable seizure outcome after surgery. Conclusion: The anatomic distribution of increased cortical complexity overlapping with limbic seizure networks in TLE and its association with hippocampal maldevelopment further imply that neurodevelopmental factors may play a role in the epileptogenic process of TLE. PMID:21148116

  12. Focal cortical damage parallels cognitive impairment in minimal hepatic encephalopathy.

    PubMed

    Montoliu, Carmina; Gonzalez-Escamilla, Gabriel; Atienza, Mercedes; Urios, Amparo; Gonzalez, Olga; Wassel, Abdallah; Aliaga, Roberto; Giner-Duran, Remedios; Serra, Miguel A; Rodrigo, Jose M; Belloch, Vicente; Felipo, Vicente; Cantero, Jose L

    2012-07-16

    Little attention has been paid to cortical integrity in patients with minimal hepatic encephalopathy (MHE), although cognitive functions affected in early stages of liver disease are mainly allocated in different neocortical structures. Here we used cortical surface-based analysis techniques to investigate if patterns of cortical thinning accompany the mildest form of HE. To aim this goal, cortical thickness obtained from high-resolution 3T magnetic resonance imaging (MRI) was measured in patients with no MHE (NMHE), MHE, and healthy controls. Further correlation analyses were performed to examine whether scores in the critical flicker frequency (CFF) test, and blood ammonia levels accounted for the loss of cortical integrity in different stages of liver disease. Finally, we assessed group differences in volume of different subcortical regions and their potential relationships with CFF scores/blood ammonia levels. Results showed a focal thinning of the superior temporal cortex and precuneus in MHE patients when compared with NMHE and controls. Relationships between blood ammonia levels and cortical thickness of the calcarine sulcus accounted for impaired visual judgment in patients with MHE when compared to NMHE. Regression analyses between cortical thickness and CFF predicted differences between controls and the two groups of HE patients, but failed to discriminate between patients with NMHE and MHE. Taking together, these findings provide the first report of cortical thinning in MHE patients, and they yield novel insights into the neurobiological basis of cognitive impairment associated with early stages of liver diseases. PMID:22465844

  13. Increased Cortical Thickness in Professional On-Line Gamers

    PubMed Central

    Hyun, Gi Jung; Shin, Yong Wook; Kim, Bung-Nyun; Cheong, Jae Hoon; Jin, Seong Nam

    2013-01-01

    Objective The bulk of recent studies have tested whether video games change the brain in terms of activity and cortical volume. However, such studies are limited by several factors including cross-sectional comparisons, co-morbidity, and short-term follow-up periods. In the present study, we hypothesized that cognitive flexibility and the volume of brain cortex would be correlated with the career length of on-line pro-gamers. Methods High-resolution magnetic resonance scans were acquired in twenty-three pro-gamers recruited from StarCraft pro-game teams. We measured cortical thickness in each individual using FreeSurfer and the cortical thickness was correlated with the career length and the performance of the pro-gamers. Results Career length was positively correlated with cortical thickness in three brain regions: right superior frontal gyrus, right superior parietal gyrus, and right precentral gyrus. Additionally, increased cortical thickness in the prefrontal cortex was correlated with winning rates of the pro-game league. Increased cortical thickness in the prefrontal and parietal cortices was also associated with higher performance of Wisconsin Card Sorting Test. Conclusion Our results suggest that in individuals without pathologic conditions, regular, long-term playing of on-line games is associated with volume changes in the prefrontal and parietal cortices, which are associated with cognitive flexibility. PMID:24474988

  14. Cortical Network for Reading Linear Words in an Alphasyllabary

    ERIC Educational Resources Information Center

    Das, Tanusree; Bapi, Raju S.; Padakannaya, Prakash; Singh, Nandini C.

    2011-01-01

    Functional imaging studies have established cortical networks for reading alphabetic, syllabic and logographic scripts. There is little information about the different cortical areas that participate in reading an alphasyllabary. We use functional brain imaging to study the reading network for Devanagari, an alphasyllabary. Similar to syllabic…

  15. Human temporal cortical single neuron activity during working memory maintenance.

    PubMed

    Zamora, Leona; Corina, David; Ojemann, George

    2016-06-01

    The Working Memory model of human memory, first introduced by Baddeley and Hitch (1974), has been one of the most influential psychological constructs in cognitive psychology and human neuroscience. However the neuronal correlates of core components of this model have yet to be fully elucidated. Here we present data from two studies where human temporal cortical single neuron activity was recorded during tasks differentially affecting the maintenance component of verbal working memory. In Study One we vary the presence or absence of distracting items for the entire period of memory storage. In Study Two we vary the duration of storage so that distractors filled all, or only one-third of the time the memory was stored. Extracellular single neuron recordings were obtained from 36 subjects undergoing awake temporal lobe resections for epilepsy, 25 in Study one, 11 in Study two. Recordings were obtained from a total of 166 lateral temporal cortex neurons during performance of one of these two tasks, 86 study one, 80 study two. Significant changes in activity with distractor manipulation were present in 74 of these neurons (45%), 38 Study one, 36 Study two. In 48 (65%) of those there was increased activity during the period when distracting items were absent, 26 Study One, 22 Study Two. The magnitude of this increase was greater for Study One, 47.6%, than Study Two, 8.1%, paralleling the reduction in memory errors in the absence of distracters, for Study One of 70.3%, Study Two 26.3% These findings establish that human lateral temporal cortex is part of the neural system for working memory, with activity during maintenance of that memory that parallels performance, suggesting it represents active rehearsal. In 31 of these neurons (65%) this activity was an extension of that during working memory encoding that differed significantly from the neural processes recorded during overt and silent language tasks without a recent memory component, 17 Study one, 14 Study two

  16. Non-invasive brain stimulation reveals reorganized cortical outputs in amputees.

    PubMed

    Hall, E J; Flament, D; Fraser, C; Lemon, R N

    1990-08-24

    EMG responses to non-invasive electromagnetic brain stimulation (EMS) were recorded from arm muscles of congenital amputees. Responses were obtained with lower thresholds on the amputated than on the intact side and were evoked from a larger cortical area. Contracting muscles showed increased responses to EMS; the increase was more pronounced on the amputated side. Similar findings were obtained in one traumatic amputee who suffered an early amputation, but not in another patient with a late amputation. We conclude that in congenital amputees there is substantial reorganisation of the corticospinal system and that this may also occur in early traumatic cases. PMID:2243618

  17. [Multineuronal cortical activity in dogs with a defensive instrumental conditioned reflex].

    PubMed

    Dolbakian, E E; Merzhanova, G Kh; Tveritskaia, I N

    1989-01-01

    By methods of correlation analysis, interrelations were studied of neurones with high, mean and low amplitudes of spikes singled out by amplitude principle from background multineuronal activity of the motor and somatosensory cortical zones, recorded by chronically implanted semi-microelectrodes in dogs. In trained animals, a high positive correlation was observed of singled out neurones discharges, particularly between the neurones with low and mean amplitude of spikes. By the method of cross-interval histogram, dependent relations were revealed of the neurones with different amplitude characteristic mainly of one-sided excitatory character. PMID:2603558

  18. Quantification of the cortical contribution to the NIRS signal over the motor cortex using concurrent NIRS-fMRI measurements

    PubMed Central

    Gagnon, Louis; Yücel, Meryem A.; Dehaes, Mathieu; Cooper, Robert J.; Perdue, Katherine L.; Selb, Juliette; Huppert, Theodore J.; Hoge, Richard D.; Boas, David A.

    2011-01-01

    Near-Infrared Spectroscopy (NIRS) measures the functional hemodynamic response occuring at the surface of the cortex. Large pial veins are located above the surface of the cerebral cortex. Following activation, these veins exhibit oxygenation changes but their volume likely stays constant. The back-reflection geometry of the NIRS measurement renders the signal very sensitive to these superficial pial veins. As such, the measured NIRS signal contains contributions from both the cortical region as well as the pial vasculature. In this work, the cortical contribution to the NIRS signal was investigated using (1) Monte Carlo simulations over a realistic geometry constructed from anatomical and vascular MRI and (2) multimodal NIRS-BOLD recordings during motor stimulation. A good agreement was found between the simulations and the modeling analysis of in vivo measurements. Our results suggest that the cortical contribution to the deoxyhemoglobin signal change (ΔHbR) is equal to 16–22% of the cortical contribution to the total hemoglobin signal change (ΔHbT). Similarly, the cortical contribution of the oxyhemoglobin signal change (ΔHbO) is equal to 73–79% of the cortical contribution to the ΔHbT signal. These results suggest that ΔHbT is far less sensitive to pial vein contamination and therefore, it is likely that the ΔHbT signal provides better spatial specificity and should be used instead of ΔHbO or ΔHbR to map cerebral activity with NIRS. While different stimuli will result in different pial vein contributions, our finger tapping results do reveal the importance of considering the pial contribution. PMID:22036999

  19. CNTF-Treated Astrocyte Conditioned Medium Enhances Large-Conductance Calcium-Activated Potassium Channel Activity in Rat Cortical Neurons.

    PubMed

    Sun, Meiqun; Liu, Hongli; Xu, Huanbai; Wang, Hongtao; Wang, Xiaojing

    2016-08-01

    Seizure activity is linked to astrocyte activation as well as dysfunctional cortical neuron excitability produced from changes in calcium-activated potassium (KCa) channel function. Ciliary neurotrophic factor-treated astrocyte conditioned medium (CNTF-ACM) can be used to investigate the peripheral effects of activated astrocytes upon cortical neurons. However, CNTF-ACM's effect upon KCa channel activity in cultured cortical neurons has not yet been investigated. Whole-cell patch clamp recordings were performed in rat cortical neurons to evaluate CNTF-ACM's effects upon charybdotoxin-sensitive large-conductance KCa (BK) channel currents and apamin-sensitive small-conductance KCa (SK) channel current. Biotinylation and RT-PCR were applied to assess CNTF-ACM's effects upon the protein and mRNA expression, respectively, of the SK channel subunits SK2 and SK3 and the BK channel subunits BKα1 and BKβ3. An anti-fibroblast growth factor-2 (FGF-2) monoclonal neutralizing antibody was used to assess the effects of the FGF-2 component of CNTF-ACM. CNTF-ACM significantly increased KCa channel current density, which was predominantly attributable to gains in BK channel activity (p < 0.05). CNTF-ACM produced a significant increase in BKα1 and BKβ3 expression (p < 0.05) but had no significant effect upon SK2 or SK3 expression (p > 0.05). Blocking FGF-2 produced significant reductions in KCa channel current density (p > 0.05) as well as BKα1 and BKβ3 expression in CNTF-ACM-treated neurons (p > 0.05). CNTF-ACM significantly enhances BK channel activity in rat cortical neurons and that FGF-2 is partially responsible for these effects. CNTF-induced astrocyte activation results in secretion of neuroactive factors which may affect neuronal excitability and resultant seizure activity in mammalian cortical neurons. PMID:27097551

  20. Multimodal antidepressant vortioxetine increases frontal cortical oscillations unlike escitalopram and duloxetine – a quantitative EEG study in rats

    PubMed Central

    Leiser, S C; Pehrson, A L; Robichaud, P J; Sanchez, C

    2014-01-01

    Background and Purpose EEG studies show that 5-HT is involved in regulation of sleep–wake state and modulates cortical oscillations. Vortioxetine is a 5-HT3, 5-HT7, and 5-HT1D receptor antagonist, 5-HT1B partial agonist, 5-HT1A agonist, and 5-HT transporter inhibitor. Preclinical (animal) and clinical studies with vortioxetine show positive impact on cognitive metrics involving cortical function. Here we assess vortioxetine's effect on cortical neuronal oscillations in actively awake rats. Experimental Approach Telemetric EEG recordings were obtained with the following treatments (mg·kg−1, s.c.): vehicle, vortioxetine (0.1, 1.0, 3.0, 10), 5-HT1A agonist flesinoxan (2.5), 5-HT3 antagonist ondansetron (0.30), 5-HT7 antagonist SB-269970-A (10), escitalopram (2.0), duloxetine (10) and vortioxetine plus flesinoxan. Target occupancies were determined by ex vivo autoradiography. Key Results Vortioxetine dose-dependently increased wakefulness. Flesinoxan, duloxetine, ondansetron, but not escitalopram or SB-269970-A increased wakefulness. Quantitative spectral analyses showed vortioxetine alone and with flesinoxan increased θ (4–8 Hz), α (8–12 Hz) and γ (30–50 Hz) power. Duloxetine had no effect on θ and γ, but decreased α power, while escitalopram produced no changes. Ondansetron and SB-269970 (≈31–35% occupancy) increased θ power. Flesinoxan (≈41% occupancy) increased θ and γ power. Conclusions and Implications Vortioxetine increased wakefulness and increased frontal cortical activity, most likely because of its 5-HT7 and 5-HT3 antagonism and 5-HT1A agonism. Vortioxetine differs from escitalopram and duloxetine by increasing cortical θ, α and γ oscillations. These preclinical findings suggest a role of vortioxetine in modulating cortical circuits known to be recruited during cognitive behaviours and warrant further investigation as to their clinical impact. PMID:24846338

  1. Jealousy increased by induced relative left frontal cortical activity.

    PubMed

    Kelley, Nicholas J; Eastwick, Paul W; Harmon-Jones, Eddie; Schmeichel, Brandon J

    2015-10-01

    Asymmetric frontal cortical activity may be one key to the process linking social exclusion to jealous feelings. The current research examined the causal role of asymmetric frontal brain activity in modulating jealousy in response to social exclusion. Transcranial direct-current stimulation (tDCS) over the frontal cortex to manipulate asymmetric frontal cortical activity was combined with a modified version of the Cyberball paradigm designed to induce jealousy. After receiving 15 min of tDCS, participants were excluded by a desired partner and reported how jealous they felt. Among individuals who were excluded, tDCS to increase relative left frontal cortical activity caused greater levels of self-reported jealousy compared to tDCS to increase relative right frontal cortical activity or sham stimulation. Limitations concerning the specificity of this effect and implications for the role of the asymmetric prefrontal cortical activity in motivated behaviors are discussed. PMID:25844975

  2. Loss of Consciousness Is Associated with Stabilization of Cortical Activity

    PubMed Central

    Solovey, Guillermo; Alonso, Leandro M.; Yanagawa, Toru; Fujii, Naotaka; Magnasco, Marcelo O.; Cecchi, Guillermo A.

    2015-01-01

    What aspects of neuronal activity distinguish the conscious from the unconscious brain? This has been a subject of intense interest and debate since the early days of neurophysiology. However, as any practicing anesthesiologist can attest, it is currently not possible to reliably distinguish a conscious state from an unconscious one on the basis of brain activity. Here we approach this problem from the perspective of dynamical systems theory. We argue that the brain, as a dynamical system, is self-regulated at the boundary between stable and unstable regimes, allowing it in particular to maintain high susceptibility to stimuli. To test this hypothesis, we performed stability analysis of high-density electrocorticography recordings covering an entire cerebral hemisphere in monkeys during reversible loss of consciousness. We show that, during loss of consciousness, the number of eigenmodes at the edge of instability decreases smoothly, independently of the type of anesthetic and specific features of brain activity. The eigenmodes drift back toward the unstable line during recovery of consciousness. Furthermore, we show that stability is an emergent phenomenon dependent on the correlations among activity in different cortical regions rather than signals taken in isolation. These findings support the conclusion that dynamics at the edge of instability are essential for maintaining consciousness and provide a novel and principled measure that distinguishes between the conscious and the unconscious brain. SIGNIFICANCE STATEMENT What distinguishes brain activity during consciousness from that observed during unconsciousness? Answering this question has proven difficult because neither consciousness nor lack thereof have universal signatures in terms of most specific features of brain activity. For instance, different anesthetics induce different patterns of brain activity. We demonstrate that loss of consciousness is universally and reliably associated with stabilization

  3. The biology and dynamics of mammalian cortical granules

    PubMed Central

    2011-01-01

    Cortical granules are membrane bound organelles located in the cortex of unfertilized oocytes. Following fertilization, cortical granules undergo exocytosis to release their contents into the perivitelline space. This secretory process, which is calcium dependent and SNARE protein-mediated pathway, is known as the cortical reaction. After exocytosis, the released cortical granule proteins are responsible for blocking polyspermy by modifying the oocytes' extracellular matrices, such as the zona pellucida in mammals. Mammalian cortical granules range in size from 0.2 um to 0.6 um in diameter and different from most other regulatory secretory organelles in that they are not renewed once released. These granules are only synthesized in female germ cells and transform an egg upon sperm entry; therefore, this unique cellular structure has inherent interest for our understanding of the biology of fertilization. Cortical granules are long thought to be static and awaiting in the cortex of unfertilized oocytes to be stimulated undergoing exocytosis upon gamete fusion. Not till recently, the dynamic nature of cortical granules is appreciated and understood. The latest studies of mammalian cortical granules document that this organelle is not only biochemically heterogeneous, but also displays complex distribution during oocyte development. Interestingly, some cortical granules undergo exocytosis prior to fertilization; and a number of granule components function beyond the time of fertilization in regulating embryonic cleavage and preimplantation development, demonstrating their functional significance in fertilization as well as early embryonic development. The following review will present studies that investigate the biology of cortical granules and will also discuss new findings that uncover the dynamic aspect of this organelle in mammals. PMID:22088197

  4. Language Mapping in Multilingual Patients: Electrocorticography and Cortical Stimulation During Naming

    PubMed Central

    Cervenka, Mackenzie C.; Boatman-Reich, Dana F.; Ward, Julianna; Franaszczuk, Piotr J.; Crone, Nathan E.

    2011-01-01

    Multilingual patients pose a unique challenge when planning epilepsy surgery near language cortex because the cortical representations of each language may be distinct. These distinctions may not be evident with routine electrocortical stimulation mapping (ESM). Electrocorticography (ECoG) has recently been used to detect task-related spectral perturbations associated with functional brain activation. We hypothesized that using broadband high gamma augmentation (HGA, 60–150 Hz) as an index of cortical activation, ECoG would complement ESM in discriminating the cortical representations of first (L1) and second (L2) languages. We studied four adult patients for whom English was a second language, in whom subdural electrodes (a total of 358) were implanted to guide epilepsy surgery. Patients underwent ECoG recordings and ESM while performing the same visual object naming task in L1 and L2. In three of four patients, ECoG found sites activated during naming in one language but not the other. These language-specific sites were not identified using ESM. In addition, ECoG HGA was observed at more sites during L2 versus L1 naming in two patients, suggesting that L2 processing required additional cortical resources compared to L1 processing in these individuals. Post-operative language deficits were identified in three patients (one in L2 only). These deficits were predicted by ECoG spectral mapping but not by ESM. These results suggest that pre-surgical mapping should include evaluation of all utilized languages to avoid post-operative functional deficits. Finally, this study suggests that ECoG spectral mapping may potentially complement the results of ESM of language. PMID:21373361

  5. Mapping Sensorimotor Cortex Using Slow Cortical Potential Resting-State Networks While Awake and Under Anesthesia

    PubMed Central

    Breshears, Jonathan D.; Gaona, Charles M.; Roland, Jarod L.; Sharma, Mohit; Bundy, David T.; Shimony, Joshua S.; Rashid, Samiya; Eisenman, Lawrence N.; Hogan, R. Edward; Snyder, Abraham Z.; Leuthardt, Eric C.

    2015-01-01

    Background The emerging insight into resting-state cortical networks has been important in understanding the fundamental architecture of brain organization. These networks, which were originally identified with functional MRI, are also seen in the correlation topography of the infraslow rhythms of local field potentials. Because of the fundamental nature of these networks and their independence from task-related activations, we posit that in addition to their neuroscientific relevance, these slow cortical potential (SCP) networks could also play an important role in clinical brain mapping. Objective We hypothesized that these networks would be useful in identifying eloquent cortex, such as sensorimotor cortex, in patients both awake and under anesthesia. Methods This study included eight subjects undergoing surgical treatment for intractable epilepsy. SCPs were recorded from the cortical surface while awake and under propofol anesthesia. To test brain-mapping utility, slow cortical potential networks were identified using data-driven (seed-independent) and anatomy-driven (seed-based) approaches. Using electrocortical stimulation as the gold standard for comparison, the sensitivity and specificity of these networks for identifying sensorimotor cortex was calculated. Results Networks identified with a data-driven approach in patients under anesthesia and awake were 90% and 93% sensitive, and 58% and 55% specific for sensorimotor cortex, respectively. Networks identified with systematic seed selection in patients under anesthesia and awake were 78% and 83% sensitive, and 67% and 60% specific, respectively. Conclusion Resting-state networks may be useful for tailoring stimulation mapping and could provide a means of identifying eloquent regions in patients while under anesthesia. PMID:22517255

  6. Baicalein reverts L-valine-induced persistent sodium current up-modulation in primary cortical neurons.

    PubMed

    Caioli, Silvia; Candelotti, Elena; Pedersen, Jens Z; Saba, Luana; Antonini, Alessia; Incerpi, Sandra; Zona, Cristina

    2016-04-01

    L-valine is a branched-chain amino acid (BCAA) largely used as dietary integrator by athletes and involved in some inherited rare diseases such as maple syrup urine disease. This pathology is caused by an altered BCAA metabolism with the accumulation of toxic keto acids in tissues and body fluids with consequent severe neurological symptoms. In animal models of BCAA accumulation, increased oxidative stress levels and lipid peroxidation have been reported. The aim of this study was to analyze both whether high BCAA concentrations in neurons induce reactive oxygen species (ROS) production and whether, by performing electrophysiological recordings, the neuronal functional properties are modified. Our results demonstrate that in primary cortical cultures, a high dose of valine increases ROS production and provokes neuronal hyperexcitability because the action potential frequencies and the persistent sodium current amplitudes increase significantly compared to non-treated neurons. Since Baicalein, a flavone obtained from the Scutellaria root, has been shown to act as a strong antioxidant with neuroprotective effects, we evaluated its possible antioxidant activity in primary cortical neurons chronically exposed to L-valine. The preincubation of cortical neurons with Baicalein prevents the ROS production and is able to revert both the neuronal hyperexcitability and the increase of the persistent sodium current, indicating a direct correlation between the ROS production and the altered physiological parameters. In conclusion, our data show that the electrophysiological alterations of cortical neurons elicited by high valine concentration are due to the increase in ROS production, suggesting much caution in the intake of BCAA dietary integrators. PMID:26721313

  7. Cortical organization of language pathways in children with non-localized cryptogenic epilepsy.

    PubMed

    Frye, Richard Eugene; Liederman, Jacqueline

    2014-01-01

    Children with a history of epilepsy are almost six times more likely than their unaffected siblings to be referred for speech or language therapy. However, the abnormalities in neural pathway that cause these delays are poorly understood. We recorded evoked fields using whole-head magnetoencephalography during real and non-word visual and auditory rhyme tasks in 15 children with non-localized cryptogenic epilepsy. Basic phonological and orthographic language skills were assessed using Woodcock-Johnson Test of Achievement subtests. Dynamic statistical parameter mapping was used with individual participant magnetic resonance images. Significant cortical activity was visualized on average and performance weighted maps. For the auditory rhyme tasks, bilateral primary and secondary auditory cortices, the superior temporal sulcus, and insular cortex were activated early with later increases in left hemisphere activity. Visual rhyme tasks evoked early bilateral primary and secondary occipital cortical and angular gyri activity followed by later activation of the planum temporale and supramarginal gyri and the left ventral occipitotemporal area. For the auditory rhyme tasks, performance weighted maps demonstrated that early right hemisphere activation was associated with poorer reading skills while later activity was associated with better reading skills; for the left hemisphere, greater early activation of the secondary auditory cortex, including the planum temporale, was related to better reading skills while relatively later activation of these areas was associated with poorer reading skills. For the visual rhyme tasks, greater activity in the bilateral ventral occipitotemporal and insular areas and angular and supramarginal gyri were associated with better performance. These data suggest that spatiotemporal cortical activation patterns are associated with variations in language performance in non-localized cryptogenic epilepsy. PMID:25346681

  8. Exercise induces cortical plasticity after neonatal spinal cord injury in the rat.

    PubMed

    Kao, Tina; Shumsky, Jed S; Murray, Marion; Moxon, Karen A

    2009-06-10

    Exercise-induced cortical plasticity is associated with improved functional outcome after brain or nerve injury. Exercise also improves functional outcomes after spinal cord injury, but its effects on cortical plasticity are not known. The goal of this investigation was to study the effect of moderate exercise (treadmill locomotion, 3 min/d, 5 d/week) on the somatotopic organization of forelimb and hindlimb somatosensory cortex (SI) after neonatal thoracic transection. We used adult rats spinalized as neonates because some of these animals develop weight-supported stepping, and, therefore, the relationship between cortical plasticity and stepping could also be examined. Acute, single-neuron mapping was used to determine the percentage of cortical cells responding to cutaneous forelimb stimulation in normal, spinalized, and exercised spinalized rats. Multiple single-neuron recording from arrays of chronically implanted microwires examined the magnitude of response of these cells in normal and exercised spinalized rats. Our results show that exercise not only increased the percentage of responding cells in the hindlimb SI but also increased the magnitude of the response of these cells. This increase in response magnitude was correlated with behavioral outcome measures. In the forelimb SI, neonatal transection reduced the percentage of responding cells to forelimb stimulation, but exercise reversed this loss. This restoration in the percentage of responding cells after exercise was accompanied by an increase in their response magnitude. Therefore, the increase in responsiveness of hindlimb SI to forelimb stimulation after neonatal transection and exercise may be due, in part, to the effect of exercise on the forelimb SI. PMID:19515923

  9. Resting state cortical electroencephalographic rhythms in subjects with normal and abnormal body weight.

    PubMed

    Babiloni, Claudio; Marzano, Nicola; Lizio, Roberta; Valenzano, Anna; Triggiani, Antonio Ivano; Petito, Annamaria; Bellomo, Antonello; Lecce, Brunello; Mundi, Ciro; Soricelli, Andrea; Limatola, Cristina; Cibelli, Giuseppe; Del Percio, Claudio

    2011-09-15

    It is well known that resting state regional cerebral blood flow is abnormal in obese when compared to normal-weight subjects but the underlying neurophysiological mechanisms are poorly known. To address this issue, we tested the hypothesis that amplitude of resting state cortical electroencephalographic (EEG) rhythms differ among underweight, normal-weight, and overweight/obese subjects as a reflection of the relationship between cortical neural synchronization and regulation of body weight. Eyes-closed resting state EEG data were recorded in 16 underweight subjects, 25 normal-weight subjects, and 18 overweight/obese subjects. All subjects were psychophysically healthy (no eating disorders or major psychopathologies). EEG rhythms of interest were delta (2-4Hz), theta (4-8Hz), alpha 1 (8-10.5Hz), alpha 2 (10.5-13Hz), beta 1 (13-20Hz), beta 2 (20-30Hz), and gamma (30-40Hz). EEG cortical sources were estimated by low-resolution brain electromagnetic tomography (LORETA). Statistical results showed that parietal and temporal alpha 1 sources fitted the pattern underweight>normal-weight>overweight/obese (p<0.004), whereas occipital alpha 1 sources fitted the pattern normal-weight>underweight>overweight/obese (p<0.00003). Furthermore, amplitude of the parietal, occipital, and temporal alpha 2 sources was stronger in the normal-weight subjects than in the underweight and overweight/obese subjects (p<0.0007). These results suggest that abnormal weight in healthy overweight/obese subjects is related to abnormal cortical neural synchronization at the basis of resting state alpha rhythms and fluctuation of global brain arousal. PMID:21704716

  10. Effects of deuterium oxide and galvanic vestibular stimulation on visual cortical cell function

    SciTech Connect

    Reinis, S.; Landolt, J.P.; Weiss, D.S.; Money, K.E.

    1984-03-01

    The spontaneous and evoked unit activities of complex visual cortical cells were recorded from Brodmann's area 18 in immobilized, unanesthetized cats before, during, and after stimulation of the vestibular system. The vestibular system was stimulated by intravenous injection of deuterium oxide (D2O)--a noted nystagmogenic agent--or by direct galvanic stimulation of the labyrinth. Measures of the receptive-field areas, poststimulus time histograms, directional preferences, and the optimal speed of the light bar stimulating the cell were obtained before and after the application of D2O. Directional preferences were determined in a novel manner, using a method derived from a hierarchical clustering technique. Data were collected and analyzed from a) visual cortical cells in cats with intact labyrinths, b) visual cortical cells in cats following bilateral labrinthectomies, and c) nonvisual cortical cells in cats with intact labyrinths. The other cellular characteristics were also altered by the D2O. Galvanic stimulation of the labyrinth resembles, in its effects, the injection of D2O. In labyrinth-intact cats, the time course of area 18 spontaneous activity dramatically increased 30 min or more after D2O was administered. It peaked 2-3 h later and still had not returned to preinjection levels even 7 h after the D2O administration. In bilaterally labyrinthectomized cats, the spontaneous activity of the visual cells did not change following D2O administration. In nonvisual cells from labyrinth-intact cats, the spontaneous activity demonstrated a slight but significant decrease over time after D2O injection. In pilot studies, the cats were injected with D2O. Within 8-10 min afterward, signs of positional nystagmus commenced; and within 30 min, problems in maintaining balance were noted. This continued for 7-8 h before disappearing. In the labyrinthectomized animals, such effects were not observed.

  11. During postnatal development endogenous neurosteroids influence GABA-ergic neurotransmission of mouse cortical neurons

    PubMed Central

    Brown, Adam R.; Mitchell, Scott J.; Peden, Dianne R.; Herd, Murray B.; Seifi, Mohsen; Swinny, Jerome D.; Belelli, Delia; Lambert, Jeremy J.

    2016-01-01

    As neuronal development progresses, GABAergic synaptic transmission undergoes a defined program of reconfiguration. For example, GABAA receptor (GABAAR)-mediated synaptic currents, (miniature inhibitory postsynaptic currents; mIPSCs), which initially exhibit a relatively slow decay phase, become progressively reduced in duration, thereby supporting the temporal resolution required for mature network activity. Here we report that during postnatal development of cortical layer 2/3 pyramidal neurons, GABAAR-mediated phasic inhibition is influenced by a resident neurosteroid tone, which wanes in the second postnatal week, resulting in the brief phasic events characteristic of mature neuronal signalling. Treatment of cortical slices with the immediate precursor of 5α-pregnan-3α-ol-20-one (5α3α), the GABAAR-inactive 5α-dihydroprogesterone, (5α-DHP), greatly prolonged the mIPSCs of P20 pyramidal neurons, demonstrating these more mature neurons retain the capacity to synthesize GABAAR-active neurosteroids, but now lack the endogenous steroid substrate. Previously, such developmental plasticity of phasic inhibition was ascribed to the expression of synaptic GABAARs incorporating the α1 subunit. However, the duration of mIPSCs recorded from L2/3 cortical neurons derived from α1 subunit deleted mice, were similarly under the developmental influence of a neurosteroid tone. In addition to principal cells, synaptic GABAARs of L2/3 interneurons were modulated by native neurosteroids in a development-dependent manner. In summary, local neurosteroids influence synaptic transmission during a crucial period of cortical neurodevelopment, findings which may be of importance for establishing normal network connectivity. PMID:26626485

  12. Cortical Hubs Form a Module for Multisensory Integration on Top of the Hierarchy of Cortical Networks

    PubMed Central

    Zamora-López, Gorka; Zhou, Changsong; Kurths, Jürgen

    2009-01-01

    Sensory stimuli entering the nervous system follow particul