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1

Stimulus Characteristics for Vestibular Stochastic Resonance to Improve Balance Function  

NASA Technical Reports Server (NTRS)

Stochastic resonance (SR) is a mechanism by which noise can enhance the response of neural systems to relevant sensory signals. Studies have shown that imperceptible stochastic vestibular electrical stimulation, when applied to normal young and elderly subjects, significantly improved their ocular stabilization reflexes in response to whole-body tilt as well as balance performance during postural disturbances. The goal of this study was to optimize the amplitude characteristics of the stochastic vestibular signals for balance performance during standing on an unstable surface. Subjects performed a standard balance task of standing on a block of foam with their eyes closed. Bipolar stochastic electrical stimulation was applied to the vestibular system using constant current stimulation through electrodes placed over the mastoid process behind the ears. Amplitude of the signals varied in the range of 0-700 microamperes. Balance performance was measured using a force plate under the foam block, and inertial motion sensors were placed on the torso and head. Balance performance with stimulation was significantly greater (10%-25%) than with no stimulation. The signal amplitude at which performance was maximized was in the range of 100-300 microamperes. Optimization of the amplitude of the stochastic signals for maximizing balance performance will have a significant impact on development of vestibular SR as a unique system to aid recovery of function in astronauts after long-duration space flight or in patients with balance disorders.

Mulavara, Ajitkumar; Fiedler, Matthew; Kofman, Igor; Peters, Brian; Wood, Scott; Serrado, Jorge; Cohen, Helen; Reschke, Millard; Bloomberg, Jacob

2010-01-01

2

Improving balance function using vestibular stochastic resonance: optimizing stimulus characteristics.  

PubMed

Stochastic resonance (SR) is a phenomenon whereby the response of a non-linear system to a weak periodic input signal is optimized by the presence of a particular non-zero level of noise. Stochastic resonance using imperceptible stochastic vestibular electrical stimulation, when applied to normal young and elderly subjects, has been shown to significantly improve ocular stabilization reflexes in response to whole-body tilt; improved balance performance during postural disturbances and optimize covariance between the weak input periodic signals introduced via venous blood pressure receptors and the heart rate responses. In our study, 15 subjects stood on a compliant surface with their eyes closed. They were given low-amplitude binaural bipolar stochastic electrical stimulation of the vestibular organs in two frequency ranges of 1-2 and 0-30 Hz over the amplitude range of 0 to ±700 ?A. Subjects were instructed to maintain an upright stance during 43-s trials, which consisted of baseline (zero amplitude) and stimulation (non-zero amplitude) periods. Measures of stability of the head and trunk using inertial motion unit sensors attached to these segments and the whole body using a force plate were measured and quantified in the mediolateral plane. Using a multivariate optimization criterion, our results show that the low levels of vestibular stimulation given to the vestibular organs improved balance performance in normal healthy subjects in the range of 5-26% consistent with the stochastic resonance phenomenon. In our study, 8 of 15 and 10 of 15 subjects were responsive for the 1-2- and 0-30-Hz stimulus signals, respectively. The improvement in balance performance did not differ significantly between the stimulations in the two frequency ranges. The amplitude of optimal stimulus for improving balance performance was predominantly in the range of ±100 to ±400 ?A. A device based on SR stimulation of the vestibular system might be useful as either a training modality to enhance adaptability or skill acquisition, or as a miniature patch-type stimulator that may be worn by people with disabilities due to aging or disease to improve posture and locomotion function. PMID:21442221

Mulavara, Ajitkumar P; Fiedler, Matthew J; Kofman, Igor S; Wood, Scott J; Serrador, Jorge M; Peters, Brian; Cohen, Helen S; Reschke, Millard F; Bloomberg, Jacob J

2011-04-01

3

Development of Vestibular Stochastic Resonance as a Sensorimotor Countermeasure: Improving Otolith Ocular and Motor Task Responses  

NASA Technical Reports Server (NTRS)

Astronauts experience disturbances in sensorimotor function after spaceflight during the initial introduction to a gravitational environment, especially after long-duration missions. Stochastic resonance (SR) is a mechanism by which noise can assist and enhance the response of neural systems to relevant, imperceptible sensory signals. We have previously shown that imperceptible electrical stimulation of the vestibular system enhances balance performance while standing on an unstable surface. The goal of our present study is to develop a countermeasure based on vestibular SR that could improve central interpretation of vestibular input and improve motor task responses to mitigate associated risks.

Mulavara, Ajitkumar; Fiedler, Matthew; DeDios,Yiri E.; Galvan, Raquel; Bloomberg, Jacob; Wood, Scott

2011-01-01

4

Optimization of Stimulus Characteristics for Vestibular Stochastic Resonance to Improve Balance Function  

NASA Technical Reports Server (NTRS)

Stochastic resonance (SR) is a mechanism by which noise can assist and enhance the response of neural systems to relevant sensory signals. Recent studies have shown that applying imperceptible stochastic noise electrical stimulation to the vestibular system significantly improved balance and ocular motor responses. The goal of this study was to optimize the amplitude of the stochastic vestibular signals for balance performance during standing on an unstable surface. Subjects performed a standardized balance task of standing on a block of 10-cm-thick medium-density foam with their eyes closed. Balance performance was measured using a force plate under the foam block and using inertial motion sensors placed on the torso and head segments. Stochastic electrical stimulation was applied to the vestibular system through electrodes placed over the mastoid process. Subjects were tested at seven amplitudes in the 0.01-30Hz frequency range. The root mean square of the signal increased by 30 microamperes for each +/-100 microampere increment in the current range of 0 - +/-700 microampere. Six balance parameters were calculated to characterize the performance of subjects during the baseline and the stimulus periods for all seven amplitudes. Optimal stimulus amplitude was determined as the one at which the ratio of parameters from the stimulus period to the baseline period for any amplitude range was less than that for the no stimulus condition on a minimum of four of six parameters. Results from this study showed that balance performance at the optimal stimulus amplitude showed significant improvement with the application of the vestibular SR stimulation. The amplitude of optimal stimulus for improving balance performance in normal subjects was in the range of +/-100 - +/-300 microamps.

Mulavara, Ajitkumar; Fiedler, Matthew; Kofman, Igor; Acock, Keena; DeDios, Yiri E.; Heap, Erin; Peters, Brian; Wood, Scott; Serrador, Jorge; Cohen, Helen; Reschke, Millard; Bloomberg, Jacob

2010-01-01

5

Estimation of an Optimal Stimulus Amplitude for Using Vestibular Stochastic Stimulation to Improve Balance Function  

NASA Technical Reports Server (NTRS)

Sensorimotor changes such as postural and gait instabilities can affect the functional performance of astronauts when they transition across different gravity environments. We are developing a method, based on stochastic resonance (SR), to enhance information transfer by applying non-zero levels of external noise on the vestibular system (vestibular stochastic resonance, VSR). The goal of this project was to determine optimal levels of stimulation for SR applications by using a defined vestibular threshold of motion detection.

Goel, R.; Kofman, I.; DeDios, Y. E.; Jeevarajan, J.; Stepanyan, V.; Nair, M.; Congdon, S.; Fregia, M.; Peters, B.; Cohen, H.; Wood, S.; Bloomberg, J. J.; Mulavara, A. P.

2015-01-01

6

Improving Sensorimotor Function Using Stochastic Vestibular Stimulation  

NASA Technical Reports Server (NTRS)

Astronauts experience sensorimotor changes during spaceflight, particularly during G-transition phases. Post flight sensorimotor changes may include postural and gait instability, spatial disorientation, and visual performance decrements, all of which can degrade operational capabilities of the astronauts and endanger the crew. Crewmember safety would be improved if these detrimental effects of spaceflight could be mitigated by a sensorimotor countermeasure and even further if adaptation to baseline could be facilitated. The goal of this research is to investigate the potential use of stochastic vestibular stimulation (SVS) as a technology to improve sensorimotor function. We hypothesize that low levels of SVS will improve sensorimotor performance through stochastic resonance (SR). The SR phenomenon occurs when the response of a nonlinear system to a weak input signal is optimized by the application of a particular nonzero level of noise. Two studies have been initiated to investigate the beneficial effects and potential practical usage of SVS. In both studies, electrical vestibular stimulation is applied via electrodes on the mastoid processes using a constant current stimulator. The first study aims to determine the repeatability of the effect of vestibular stimulation on sensorimotor performance and perception in order to better understand the practical use of SVS. The beneficial effect of low levels of SVS on balance performance has been shown in the past. This research uses the same balance task repeated multiple times within a day and across days to study the repeatability of the stimulation effects. The balance test consists of 50 sec trials in which the subject stands with his or her feet together, arms crossed, and eyes closed on compliant foam. Varying levels of SVS, ranging from 0-700 micro A, are applied across different trials. The subject-specific optimal SVS level is that which results in the best balance performance as measured by inertial measurement units placed on the upper and lower torso of the subjects. Additionally, each individual’s threshold for illusory motion perception of suprasensory electrical vestibular stimulation is measured multiple times within and across days to better understand how multiple SVS test methods compare. The second study aims to demonstrate stochastic resonance in the vestibular system using a perception based motion recognition task. This task measures an individual’s velocity threshold of motion recognition using a 6-degree of freedom Stewart platform and a 3-down/1-up staircase procedure. For this study, thresholds are determined using 150 trials in the upright, head-centered roll tilt motion direction at a 0.2 Hz frequency. We aim to demonstrate the characteristic bell shaped curve associated with stochastic resonance with each subject’s motion recognition thresholds at varying SVS levels ranging from 0 to 1500 micro A. The curve includes the individual’s baseline threshold with no SVS, optimal or minimal threshold at some mid-level of SVS, and finally degraded or increased threshold at a high SVS level. An additional aim is to formally retest each subject at his or her individual optimal SVS level on a different day than the original testing for additional validity. The overall purpose of this research is to further quantify the effects of SVS on various sensorimotor tasks and investigate the practical implications of its use in the context of human space flight so that it may be implemented in the future as a component of a comprehensive countermeasure plan for adaptation to G-transitions.

Galvan, R. C.; Clark, T. K.; Merfeld, D. M.; Bloomberg, J. J.; Mulavara, A. P.; Oman, C. M.

2014-01-01

7

Determine Optimal Stimulus Amplitude for Using Vestibular Stochastic Stimulation to Improve Balance Function  

NASA Technical Reports Server (NTRS)

Sensorimotor changes such as postural and gait instabilities can affect the functional performance of astronauts when they transition across different gravity environments. We are developing a method, based on stochastic resonance (SR), to enhance information transfer by applying non-zero levels of external noise on the vestibular system (vestibular stochastic resonance, VSR). Our previous work has shown the advantageous effects of VSR in a balance task of standing on an unstable surface [1]. This technique to improve detection of vestibular signals uses a stimulus delivery system that provides imperceptibly low levels of white noise-based binaural bipolar electrical stimulation of the vestibular system. The goal of this project is to determine optimal levels of stimulation for SR applications by using a defined vestibular threshold of motion detection. A series of experiments were carried out to determine a robust paradigm to identify a vestibular threshold that can then be used to recommend optimal stimulation levels for sensorimotor adaptability (SA) training applications customized to each crewmember. The amplitude of stimulation to be used in the VSR application has varied across studies in the literature such as 60% of nociceptive stimulus thresholds [2]. We compared subjects' perceptual threshold with that obtained from two measures of body sway. Each test session was 463s long and consisted of several 15s long sinusoidal stimuli, at different current amplitudes (0-2 mA), interspersed with 20-20.5s periods of no stimulation. Subjects sat on a chair with their eyes closed and had to report their perception of motion through a joystick. A force plate underneath the chair recorded medio-lateral shear forces and roll moments. Comparison of threshold of motion detection obtained from joystick data versus body sway suggests that perceptual thresholds were significantly lower. In the balance task, subjects stood on an unstable surface and had to maintain balance, and the stimulation was administered from 20-400% of subjects' vestibular threshold. Optimal stimulation amplitude was determined at which the balance performance was best compared to control (no stimulation). Preliminary results show that, in general, using stimulation amplitudes at 40-60% of perceptual motion threshold significantly improved the balance performance. We hypothesize that VSR stimulation will act synergistically with SA training to improve adaptability by increasing utilization of vestibular information and therefore will help us to optimize and personalize a SA countermeasure prescription. This combination may help to significantly reduce the number of days required to recover functional performance to preflight levels after long-duration spaceflight.

Goel, R.; Kofman, I.; DeDios, Y. E.; Jeevarajan, J.; Stepanyan, V.; Nair, M.; Congdon, S.; Fregia, M.; Cohen, H.; Bloomberg, J.J.; Mulavara, A.P.

2015-01-01

8

Optimal Stimulus Amplitude for Vestibular Stochastic Stimulation to Improve Sensorimotor Function  

NASA Technical Reports Server (NTRS)

Sensorimotor changes such as postural and gait instabilities can affect the functional performance of astronauts when they transition across different gravity environments. We are developing a method, based on stochastic resonance (SR), to enhance information transfer by applying non-zero levels of external noise on the vestibular system (vestibular stochastic resonance, VSR). Our previous work has shown the advantageous effects of VSR in a balance task of standing on an unstable surface. This technique to improve detection of vestibular signals uses a stimulus delivery system that is wearable or portable and provides imperceptibly low levels of white noise-based binaural bipolar electrical stimulation of the vestibular system. The goal of this project is to determine optimal levels of stimulation for SR applications by using a defined vestibular threshold of motion detection. A series of experiments were carried out to determine a robust paradigm to identify a vestibular threshold that can then be used to recommend optimal stimulation levels for SR training applications customized to each crewmember. Customizing stimulus intensity can maximize treatment effects. The amplitude of stimulation to be used in the VSR application has varied across studies in the literature such as 60% of nociceptive stimulus thresholds. We compared subjects' perceptual threshold with that obtained from two measures of body sway. Each test session was 463s long and consisted of several 15s sinusoidal stimuli, at different current amplitudes (0-2 mA), interspersed with 20-20.5s periods of no stimulation. Subjects sat on a chair with their eyes closed and had to report their perception of motion through a joystick. A force plate underneath the chair recorded medio-lateral shear forces and roll moments. First we determined the percent time during stimulation periods for which perception of motion (activity above a pre-defined threshold) was reported using the joystick, and body sway (two standard deviation of the noise level in the baseline measurement) was detected by the sensors. The percentage time at each stimulation level for motion detection was normalized with respect to the largest value and a logistic regression curve fit was applied to these data. The threshold was defined at the 50% probability of motion detection. Comparison of threshold of motion detection obtained from joystick data versus body sway suggests that perceptual thresholds were significantly lower, and were not impacted by system noise. Further, in order to determine optimal stimulation amplitude to improve balance, two sets of experiments were carried out. In the first set of experiments, all subjects received the same level of stimuli and the intensity of optimal performance was projected back on subjects' vestibular threshold curve. In the second set of experiments, on different subjects, stimulation was administered from 20-400% of subjects' vestibular threshold obtained from joystick data. Preliminary results of our study show that, in general, using stimulation amplitudes at 40-60% of perceptual motion threshold improved balance performance significantly compared to control (no stimulation). The amplitude of vestibular stimulation that improved balance function was predominantly in the range of +/- 100 to +/- 400 micro A. We hypothesize that VSR stimulation will act synergistically with sensorimotor adaptability (SA) training to improve adaptability by increasing utilization of vestibular information and therefore will help us to optimize and personalize a SA countermeasure prescription. This combination will help to significantly reduce the number of days required to recover functional performance to preflight levels after long-duration spaceflight.

Goel, R.; Kofman, I.; DeDios, Y. E.; Jeevarajan, J.; Stepanyan, V.; Nair, M.; Congdon, S.; Fregia, M.; Cohen, H.; Bloomberg, J. J.; Mulavara, A. P.

2014-01-01

9

Double Entropic Stochastic Resonance  

E-print Network

We demonstrate the appearance of a purely entropic stochastic resonance (ESR) occurring in a geometrically confined system, where the irregular boundaries cause entropic barriers. The interplay between a periodic input signal, a constant bias and intrinsic thermal noise leads to a resonant ESR-phenomenon in which feeble signals become amplified. This new phenomenon is characterized by the presence of two peaks in the spectral amplification at corresponding optimal values of the noise strength. The main peak is associated with the manifest stochastic resonance synchronization mechanism involving the inter-well noise-activated dynamics while a second peak relates to a regime of optimal sensitivity for intra-well dynamics. The nature of ESR, occurring when the origin of the barrier is entropic rather than energetic, offers new perspectives for novel investigations and potential applications. ESR by itself presents yet another case where one constructively can harvest noise in driven nonequilibrium systems.

P. S. Burada; G. Schmid; D. Reguera; J. M. Rubi; P. Hänggi

2009-08-24

10

Stochastic resonance without tuning  

Microsoft Academic Search

STOCHASTIC resonance1á¤-4 (SR) is a phenomenon wherein the response of a nonlinear system to a weak periodic input signal is optimized by the presence of a particular, non-zero level of noise5 á¤-7. SR has been proposed as a means for improving signal detection in a wide variety of systems, including superconducting quantum interference devices8, and may be used in some

J. J. Collins; Carson C. Chow; Thomas T. Imhoff

1995-01-01

11

Stochastic Resonance: from climate to biology  

E-print Network

In this paper I will review some basic aspects of the mechanism of stochastic resonance. Stochastic resonance was first introduced as a possible mechanism to explain long term climatic variation. Since then, there have been many applications of stochastic resonance in physical and biological systems. I will show that in complex system, stochastic resonance can substantially change as a function of the ``system complexity''. Also, I will briefly mention how to apply stochastic resonance for the case of Brownian motors.

Roberto Benzi

2007-02-05

12

Stochastic resonance in electrical circuits. I. Conventional stochastic resonance  

Microsoft Academic Search

Stochastic resonance (SR), a phenomenon in which a periodic signal in a nonlinear system can be amplified by added noise, is introduced and discussed. Techniques for investigating SR using electronic circuits are described in practical terms. The physical nature of SR, and the explanation of weak-noise SR as a linear response phenomenon, are considered. Conventional SR, for systems characterized by

Dmitrii G. Luchinsky; Riccardo Mannella; Peter V. E. McClintock; Nigel G. Stocks

1999-01-01

13

Stochastic Resonance and Information Processing  

NASA Astrophysics Data System (ADS)

A dynamical system giving rise to multiple steady states and subjected to noise and a periodic forcing is analyzed from the standpoint of information theory. It is shown that stochastic resonance has a clearcut signature on information entropy, information transfer and other related quantities characterizing information transduction within the system.

Nicolis, C.

2014-12-01

14

Stochastic resonance in visual sensitivity.  

PubMed

It is well known from psychophysical studies that stochastic resonance, in its simplest threshold paradigm, can be used as a tool to measure the detection sensitivity to fine details in noise contaminated stimuli. In the present manuscript, we report simulation studies conducted in the similar threshold paradigm of stochastic resonance. We have estimated the contrast sensitivity in detecting noisy sine-wave stimuli, with varying area and spatial frequency, as a function of noise strength. In all the cases, the measured sensitivity attained a peak at intermediate noise strength, which indicate the occurrence of stochastic resonance. The peak sensitivity exhibited a strong dependence on area and spatial frequency of the stimulus. We show that the peak contrast sensitivity varies with spatial frequency in a nonmonotonic fashion and the qualitative nature of the sensitivity variation is in good agreement with human contrast sensitivity function. We also demonstrate that the peak sensitivity first increases and then saturates with increasing area, and this result is in line with the results of psychophysical experiments. Additionally, we also show that critical area, denoting the saturation of contrast sensitivity, decreases with spatial frequency and the associated maximum contrast sensitivity varies with spatial frequency in a manner that is consistent with the results of psychophysical experiments. In all the studies, the sensitivities were elevated via a nonlinear filtering operation called stochastic resonance. Because of this nonlinear effect, it was not guaranteed that the sensitivities, estimated at each frequency, would be in agreement with the corresponding results of psychophysical experiments; on the contrary, close agreements were observed between our results and the findings of psychophysical investigations. These observations indicate the utility of stochastic resonance in human vision and suggest that this paradigm can be useful in psychophysical studies. PMID:25398687

Kundu, Ajanta; Sarkar, Sandip

2014-11-15

15

Stochastic resonance in electrical circuits. II. Nonconventional stochastic resonance  

Microsoft Academic Search

For pt.I see ibid., vol.46, no.9, pp.1205-14 (1999). Stochastic resonance (SR), in which a periodic signal in a nonlinear system can be amplified by added noise, is discussed. The application of circuit modeling techniques to the conventional form of SR, which occurs in static bistable potentials, was considered in a companion paper. Here, the investigation of nonconventional forms of SR

Dmitrii G. Luchinsky; Riccardo Mannella; Peter V. E. McClintock; Nigel G. Stocks

1999-01-01

16

Stochastic resonance in free-electron lasers.  

PubMed

We present evidence of stochastic resonance in free-electron lasers. In order to do that, we have analyzed theoretically the dynamics of a free-electron laser oscillator. A weak modulation and a noise source have been applied to the initial energy of the electron beam. We have found stochastic resonance for different frequencies and amplitudes of the modulation. A threshold crossing mechanism leads to the stochastic resonance in this system. PMID:11304371

Calderón, O G

2001-01-01

17

Stochastic resonance in binocular rivalry.  

PubMed

When a different image is presented to each eye, visual awareness spontaneously alternates between the two images--a phenomenon called binocular rivalry. Because binocular rivalry is characterized by two marginally stable perceptual states and spontaneous, apparently stochastic, switching between them, it has been speculated that switches in perceptual awareness reflect a double-well-potential type computational architecture coupled with noise. To characterize this noise-mediated mechanism, we investigated whether stimulus input, neural adaptation, and inhibitory modulations (thought to underlie perceptual switches) interacted with noise in such a way that the system produced stochastic resonance. By subjecting binocular rivalry to weak periodic contrast modulations spanning a range of frequencies, we demonstrated quantitative evidence of stochastic resonance in binocular rivalry. Our behavioral results combined with computational simulations provided insights into the nature of the internal noise (its magnitude, locus, and calibration) that is relevant to perceptual switching, as well as provided novel dynamic constraints on computational models designed to capture the neural mechanisms underlying perceptual switching. PMID:16183099

Kim, Yee-Joon; Grabowecky, Marcia; Suzuki, Satoru

2006-02-01

18

Spatial stochastic resonance in protein hydrophobicity [rapid communication  

NASA Astrophysics Data System (ADS)

Stochastic resonance is usually found in nonlinear dynamical systems. Spatial stochastic resonance, however, has also been described. We present a case of spatial stochastic resonance in the sequence hydrophobicities of spider silk proteins, and briefly describe its putative significance.

Zbilut, Joseph P.; Scheibel, Thomas; Huemmerich, Daniel; Webber, Charles L.; Colafranceschi, Mauro; Giuliani, Alessandro

2005-10-01

19

Stochastic resonance in attention control  

NASA Astrophysics Data System (ADS)

We investigated the beneficial role of noise in a human higher brain function, namely visual attention control. We asked subjects to detect a weak gray-level target inside a marker box either in the left or the right visual field. Signal detection performance was optimized by presenting a low level of randomly flickering gray-level noise between and outside the two possible target locations. Further, we found that an increase in eye movement (saccade) rate helped to compensate for the usual deterioration in detection performance at higher noise levels. To our knowledge, this is the first experimental evidence that noise can optimize a higher brain function which involves distinct brain regions above the level of primary sensory systems -- switching behavior between multi-stable attention states -- via the mechanism of stochastic resonance.

Kitajo, K.; Yamanaka, K.; Ward, L. M.; Yamamoto, Y.

2006-12-01

20

Stochastic resonance for exploration geophysics  

E-print Network

Stochastic resonance (SR) is a phenomenon in which signal to noise (SN) ratio gets improved by noise addition rather than removal as envisaged classically. SR was first claimed in climatology a few decades ago and then in other disciplines as well. The same as it is observed in natural systems, SR is used also for allowable SN enhancements at will. Here I report a proof of principle that SR can be useful in exploration geophysics. For this I perform high frequency GaussVanicek variance spectral analyses (GVSA) of model traces characterized by varying levels of complexity, completeness and pollution. This demonstration justifies all further research on SR in applied geophysics, as energy demands and depletion of reachable supplies potentially make SR vital in a near future.

Omerbashich, Mensur

2008-01-01

21

New measures and effects of stochastic resonance  

E-print Network

In the case of wideband (aperiodic) signals, the classical signal and noise measures used to characterize stochastic resonance do not work because their way of distinguishing signal from noise fails. In a study published earlier (L. B. Kish, 1996...

Sethuraman, Swaminathan

2005-11-01

22

Stochastic Resonance In Visual Perception  

NASA Astrophysics Data System (ADS)

Stochastic resonance (SR) is a well established physical phenomenon wherein some measure of the coherence of a weak signal can be optimized by random fluctuations, or "noise" (K. Wiesenfeld and F. Moss, Nature), 373, 33 (1995). In all experiments to date the coherence has been measured using numerical analysis of the data, for example, signal-to-noise ratios obtained from power spectra. But, can this analysis be replaced by a perceptive task? Previously we had demonstrated this possibility with a numerical model of perceptual bistability applied to the interpretation of ambiguous figures(M. Riani and E. Simonotto, Phys. Rev. Lett.), 72, 3120 (1994). Here I describe an experiment wherein SR is detected in visual perception. A recognizible grayscale photograph was digitized and presented. The picture was then placed beneath a threshold. Every pixel for which the grayscale exceeded the threshold was painted white, and all others black. For large enough threshold, the picture is unrecognizable, but the addition of a random number to every pixel renders it interpretable(C. Seife and M. Roberts, The Economist), 336, 59, July 29 (1995). However the addition of dynamical noise to the pixels much enhances an observer's ability to interpret the picture. Here I report the results of psychophysics experiments wherein the effects of both the intensity of the noise and its correlation time were studied.

Simonotto, Enrico

1996-03-01

23

Stochastic resonance in the Bénard system  

NASA Astrophysics Data System (ADS)

In this paper the effect of small stochastic perturbations on a dynamical system describing the Bénard thermal convection is studied. In particular, the two-dimensional Oberbeck-Boussinesq equations governing the dynamics of three interacting Rayleigh rolls with increasing horizontal wave numbers ( i.e., three horizontal modes in the Fourier transform) are reduced to a system of gradient type. The aim is to study the transition paths between the stable steady states, when a stochastic perturbation is taken into account, and the occurrence of stochastic resonance, when the system is perturbed by white noise and the first (gravest) mode is forced by an external periodic component. Results show that i) random transitions between stable steady states representing a clockwise and a counter-clockwise circulation occur through the two saddle points associated with the second mode and not through the (unstable) conductive state nor the saddle points related to the third mode; ii) the introduction of the third mode, as well as of others of smaller spatial scales, does not affect transitions that remain confined along the trajectories linking stable convective states through the saddle points associated with the second mode; iii) the system exhibits a stochastic resonance behavior leading to large amplification of the small amplitude periodic component compared to the one leading to the classical (one-dimensional) stochastic resonance.

Barbini, Leonardo; Bordi, Isabella; Fraedrich, Klaus

2014-09-01

24

A new perspective on stochastic resonance in monostable systems  

NASA Astrophysics Data System (ADS)

Stochastic resonance induced by multiplicative white noise is theoretically studied in forced damped monostable oscillators. A stochastic amplitude equation is derived for the oscillation envelope, which has a linear stochastic resonance. This phenomenon is persistent when nonlinearities are considered. We propose three simple systems—a horizontally driven pendulum, a forced electrical circuit and a laser with an injected signal—that display this stochastic resonance.

Calisto, H.; Clerc, M. G.

2010-11-01

25

Stochastic resonance in an intracellular genetic perceptron.  

PubMed

Intracellular genetic networks are more intelligent than was first assumed due to their ability to learn. One of the manifestations of this intelligence is the ability to learn associations of two stimuli within gene-regulating circuitry: Hebbian-type learning within the cellular life. However, gene expression is an intrinsically noisy process; hence, we investigate the effect of intrinsic and extrinsic noise on this kind of intracellular intelligence. We report a stochastic resonance in an intracellular associative genetic perceptron, a noise-induced phenomenon, which manifests itself in noise-induced increase of response in efficiency after the learning event under the conditions of optimal stochasticity. PMID:24730883

Bates, Russell; Blyuss, Oleg; Zaikin, Alexey

2014-03-01

26

Enhanced logical stochastic resonance under periodic forcing  

NASA Astrophysics Data System (ADS)

It was demonstrated recently that noise in an optimal window allows a bistable system to operate reliably as reconfigurable logic gates (Murali et al., 2009) [1], as well as a memory device (Kohar and Sinha, 2012) [11]. Namely, in a range of moderate noise, the system can operate flexibly, both as a NAND/AND/OR/NOR gate and a Set Reset latch. Here we demonstrate how the width of the optimal noise window can be increased by utilizing the constructive interplay of noise and periodic forcing, namely noise in conjunction with a periodic drive yields consistent logic outputs for all noise strengths below a certain threshold. Thus we establish that in scenarios where noise level is below the minimum threshold required for logical stochastic resonance (or stochastic resonance in general), we can add a periodic forcing to obtain the desired effects. Lastly, we also show how periodic forcing reduces the switching time, leading to faster operation of devices and lower latency effects.

Kohar, Vivek; Murali, K.; Sinha, Sudeshna

2014-08-01

27

From stochastic resonance to brain waves  

NASA Astrophysics Data System (ADS)

Biological neurons are good examples of a threshold device - this is why neural systems are in the focus when looking for realization of Stochastic Resonance (SR) and spatio-temporal stochastic resonance (STSR) phenomena. In this Letter a simple integrate-and fire model is used to demonstrate the possibility of STSR in a chain of neurons. The theoretical and computational models so far suggest that SR and STSR could occur in neural systems. However, how significant is the role played by these phenomena and what implications might they have on neurobiology is still a question. Because the direct biological proof of SR and STSR seems to be a tough issue one might look at indirect ways to decide whether the internal noise plays any constructive role in the nervous system. A loop of neurons is shown to have interesting features (frequency selection) which might supply a clue for answering the previous question.

Balázsi, G.; Kish, L. B.

2000-01-01

28

Stochastic resonance in mammalian neuronal networks  

SciTech Connect

We present stochastic resonance observed in the dynamics of neuronal networks from mammalian brain. Both sinusoidal signals and random noise were superimposed into an applied electric field. As the amplitude of the noise component was increased, an optimization (increase then decrease) in the signal-to-noise ratio of the network response to the sinusoidal signal was observed. The relationship between the measures used to characterize the dynamics is discussed. Finally, a computational model of these neuronal networks that includes the neuronal interactions with the electric field is presented to illustrate the physics behind the essential features of the experiment. {copyright} {ital 1998 American Institute of Physics.}

Gluckman, B.J.; So, P. [Department of Physics and Astronomy and The Krasnow Institute for Advanced Studies, George Mason University, Fairfax, Virginia 22030 (United States)] [Department of Physics and Astronomy and The Krasnow Institute for Advanced Studies, George Mason University, Fairfax, Virginia 22030 (United States); Netoff, T.I. [Program in Neuroscience, The George Washington University, Washington, DC 20052 (United States)] [Program in Neuroscience, The George Washington University, Washington, DC 20052 (United States); Spano, M.L. [Naval Surface Warfare Center, Carterock Division, West Bethesda, Maryland 20817 (United States)] [Naval Surface Warfare Center, Carterock Division, West Bethesda, Maryland 20817 (United States); Schiff, S.J. [The Krasnow Institute for Advanced Studies and the Department of Psychology, George Mason University, Fairfax, Virginia 22030 (United States)] [The Krasnow Institute for Advanced Studies and the Department of Psychology, George Mason University, Fairfax, Virginia 22030 (United States); [Program in Neuroscience, The George Washington University, Washington, DC 20052 (United States)

1998-09-01

29

Stochastic resonance in atomic optical bistability  

SciTech Connect

Stochastic resonance (SR) is experimentally demonstrated in an atomic optical bistable system consisting of three-level atoms in {lambda}-type configuration confined in an optical ring cavity. The optical bistable system with enhanced Kerr nonlinearity due to atomic coherence is driven by a periodic signal and a Gaussian white noise source with variable amplitude, and displays an improved output signal-to-noise ratio, a characteristic signature of SR. The measured results match qualitatively with the theoretical predictions of the generic model for the SR phenomenon.

Joshi, Amitabh; Xiao Min [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

2006-07-15

30

Switch-phase distributions and stochastic resonance  

NASA Astrophysics Data System (ADS)

The de-synchronization mechanism that occurs for noise intensities above stochastic resonance is analyzed in terms of switch-time and switch-phase distributions. In particular, we observed that (i) the switch-time distributions exhibit thicker peak structures with maxima at the multiples (both odd and even) of the half forcing period; (ii) the switch-phase distributions are doubly peaked, being dominated by the in-phase and ? out-of-phase events. The appearance of these properties of the switch statistics is discussed on the grounds of numerical simulations.

Marchesoni, F.; Apostolico, F.; Santucci, S.

1998-11-01

31

Stochastic resonance with a mesoscopic reaction-diffusion system.  

PubMed

In a mesoscopic reaction-diffusion system with an Oregonator reaction model, we show that intrinsic noise can drive a resonant stable pattern in the presence of the initial subthreshold perturbations. Both spatially periodic and aperiodic stochastic resonances are demonstrated by employing the Gillespies stochastic simulation algorithm. The mechanisms for these phenomena are discussed. PMID:25019857

Mahara, Hitoshi; Yamaguchi, Tomohiko; Parmananda, P

2014-06-01

32

Stochastic resonance with a mesoscopic reaction-diffusion system  

NASA Astrophysics Data System (ADS)

In a mesoscopic reaction-diffusion system with an Oregonator reaction model, we show that intrinsic noise can drive a resonant stable pattern in the presence of the initial subthreshold perturbations. Both spatially periodic and aperiodic stochastic resonances are demonstrated by employing the Gillespies stochastic simulation algorithm. The mechanisms for these phenomena are discussed.

Mahara, Hitoshi; Yamaguchi, Tomohiko; Parmananda, P.

2014-06-01

33

Analysis of a Signal Using Stochastic Resonance  

NASA Astrophysics Data System (ADS)

Noise hides signals when the signal amplitude is weak compared to the noise amplitude. For this reason, noise is usually considered unwanted in systems of physical interest. In threshold systems, however, noise can amplify the signal and is responsible for the response of the system. In this way noise becomes a crucial aspect of the signal. This ability of the noise to become an important component in the output of the signal is a characteristic of the phenomena of stochastic resonance. Stochastic resonance can have many applications including the detection of a weak signal, the identification of the period of the signal and knowledge on the amplitude of the signal. The investigations of Moss footnote F. Moss and K. Weisenfeld, Sci. Am. (Aug 1995), pp. 66-69, and J.K. Douglass, L. Wilkens, E. Pantazelou, and F.Moss, Nature 365, pp. 337-339 (1993) and Gammaitoni footnote L. Gammaitoni, Phys. Letters A208, 315-322 (1995). inspired our study of a threshold system consisting of a sinusoidal signal immersed in noise. The detection of the signal and identification of the period and amplitude of the signal were investigated. The period of the signal was viewed by considering the positive part of the noisy signal minus the threshold as a function of time. The analysis of the amplitude of the underlying sinusoidal signal was investigated by varying the threshold. In the future other non-linear signals immersed in noise, such as the Jacobi Sn function, will be investigated.

Flenner, Arjuna

1996-05-01

34

Improving the detection sensitivity of chromatography by stochastic resonance.  

PubMed

Improving the detection sensitivity of analytical instruments has been a challenging task for chemometricians since undetectability has been almost unavoidable in trace analysis, even under optimized experimental conditions and with the use of modern instruments. Various chemometrics methods have been developed which attempt to address this detection problem but with limited success (e.g., fast Fourier transform and wavelet transform). However, the application of stochastic resonance (SR) creates an entirely new and effective methodology. Stochastic resonance is a phenomenon which is manifested in non-linear systems where a weak signal can be amplified and optimized with the assistance of noise. In this review, we summarize the use of basic SR, optimization of parameters and its modifications, including periodic modulation stochastic resonance (PSRA), linear modulation stochastic resonance (LSRA), single-well potential stochastic resonance (SSR) and the Duffing oscillator algorithm (DOA) for amplifying sub-threshold small signals. We also review the advantages and the disadvantages of various SR procedures. PMID:24622614

Zhang, Wei; Guo, Jianru; Xiang, Bingren; Fan, Hongyan; Xu, Fengguo

2014-05-01

35

Human vestibular cortex as identified with caloric stimulation in functional magnetic resonance imaging.  

PubMed

Anatomic and electrophysiological studies in monkeys have yielded a detailed map of cortex areas receiving vestibular afferents. In contrast, comparatively little is known about the cortical representation of the human vestibular system. In this study we applied caloric stimulation and fMRI to further characterize human cortical vestibular areas and to test for hemispheric dominance of vestibular information processing. For caloric vestibular stimulation we used cold nitrogen to avoid susceptibility artifacts induced by water calorics. Right and left side vestibular stimulation was repetitively performed inducing a nystagmus for at least 90 s after the end of the stimulation in all subjects. Only the first 60 s of this nystagmus period was included for statistical analysis and compared with the baseline condition. Activation maps revealed a cortical network with right hemispheric dominance, which in all subjects comprised the temporoparietal junction extending into the posterior insula and, furthermore, the anterior insula, pre- and postcentral gyrus, areas in the parietal lobe, the ventrolateral portion of the occipital lobe, and the inferior frontal gyrus extending into the inferior part of the precentral sulcus. In conclusion, caloric stimulation in fMRI reveals a widespread cortical network involved in vestibular signal processing corresponding to the findings from animal experiments and previous functional imaging studies in humans. Furthermore, this study demonstrates a strong right hemispheric dominance of vestibular cortex areas regardless of the stimulated side, consistent with the current view of a rightward asymmetrical cortical network for spatial orientation. PMID:12414278

Fasold, Oliver; von Brevern, Michael; Kuhberg, Marc; Ploner, Christoph J; Villringer, Arno; Lempert, Thomas; Wenzel, Rüdiger

2002-11-01

36

Deterministic stochastic resonance in a Rössler oscillator.  

PubMed

We discuss the characteristics of stochastic resonancelike behavior observed in a deterministic system. If a periodically forced Rössler oscillator strays from the phase locking state, it exhibits the intermittent behavior known as phase slips. When the periodic force is modulated by a weak signal, the phase slips synchronize with the weak signal statistically. We numerically demonstrate, in terms of interslip intervals and signal to noise ratio, that the maximum synchronization can be achieved with the optimum intensity of chaotic fluctuations. It is shown that the stochastic resonancelike behavior can be observed regardless of the choice of parameters. The frequency dependence of the signal indicates that there is an optimum frequency for the maximum resonance. The phase slip rate is derived based on the fact that the phase slips are caused by a boundary crisis caused by an unstable-unstable pair bifurcation. The interslip distributions obtained from the derived slip rate and the approximation theory of the time-dependent Poisson process agree with those obtained by numerical simulations. In addition, the maximum enhancement of a weak signal is shown to be achieved by adjusting the chaotic fluctuations even if a signal becomes mixed with noise. PMID:14995544

Arai, Kenichi; Mizutani, Shin; Yoshimura, Kazuyuki

2004-02-01

37

Linear Response Theory in Stochastic Resonance  

E-print Network

The susceptibility of an overdamped Markov system fluctuating in a bistable potential of general form is obtained by analytic solution of the Fokker-Planck equation (FPE) for low noise intensities. The results are discussed in the context of the LRT theory of stochastic resonance. They go over into recent results (Gang Hu et al {\\em Phys. Lett. A} {\\bf 172}, 21, 1992) obtained from the FPE for the case of a symmetrical potential, and they coincide with the LRT results (Dykman et al, {\\em Phys. Rev. Lett.} {\\bf 65}, 2606, 1990; {\\em JETP Lett} {\\bf 52}, 144, 1990; {\\em Phys. Rev. Lett.} {\\bf 68}, 2985, 1992) obtained for the general case of bistable systems.

MI Dykman; H Haken; Gang Hu; DG Luchinsky; R Mannella; PVE McClintock; CZ Ning; ND Stein; NG Stocks

1993-08-09

38

City traffic jam relief by stochastic resonance  

NASA Astrophysics Data System (ADS)

We simulate traffic in a city by means of the evolution of a row of interacting cars, using a cellular automaton model, in a sequence of traffic lights synchronized by a "green wave". When our initial condition is a small density jammed state, its evolution shows the expected scaling laws close to the synchronization resonance, with a uniform car density along the street. However, for an initial large density jammed state, we observe density variations along the streets, which results in the breakdown of the scaling laws. This spatial disorder corresponds to a different attractor of the system. As we include velocity perturbations in the dynamics of the cars, all these attractors converge to a statistically equivalent system for all initial jammed densities. However, this emergent state shows a stochastic resonance-like behavior in which the average traffic velocity increases with respect to that of the system without noise, for several initial jammed densities. This result may help in the understanding of dynamics of traffic jams in cities.

Castillo, F.; Toledo, B. A.; Muńoz, V.; Rogan, J.; Zarama, R.; Kiwi, M.; Valdivia, J. A.

2014-06-01

39

Geomagnetic Polarity Reversals as a Stochastic Resonance Phenomenon  

NASA Astrophysics Data System (ADS)

A special class of noise-induced co-operative phenomena is represented by Stochastic Resonance (SR). In detail, stochastic resonance refers to a nonlinear process in which a very small periodic modulating signal, generally undetectable, is strongly enhanced by intrinsic random fluctuations or noise. Its essential ingredients are a bistable system with two inputs of different source: an external coherent periodic driving signal and an intrinsic noise source. In the last decade, stochastic resonance has been observed to occur in a wide variety of physical and biological systems: from bistable ring lasers to mechanoreceptor cells of crayfishes. Here, we show that geomagnetic polarity reversal phenomenon might be read as a stochastic resonance process. In detail, analysing the distribution function of polarity residence-time (chron) as observed from magnetostratigraphic measurements, we find the evidence of a stochastic synchronisation process, i.e. a series of peaks at Tn = (2n+1)T? /2 with n = 0,1, .., j and T? ~ 100 kyr. This result is discussed in the framework of dynamo theory and in connection with variation of the Earth's orbit parameters.

de Michelis, P.; Consolini, G.

2002-12-01

40

Transition times and stochastic resonance for multidimensional  

E-print Network

random trajectories follow the exterior periodic motion in an optimal fashion, i.e. for some optimal, Nicolis [12] and Benzi et al. [3] proposed a simple stochastic climate model based on an energy balance year due to periodic changes of the earth orbit's eccentricity (Mi- lankovich cycles), which coincide

41

Experimental study of the stochastic instability of resonance oscillators  

Microsoft Academic Search

The stochastic instability of resonance oscillators under biharmonic external excitation was studied experimentally. Conditions for the appearance of chaos are established, and related to the oscillator characteristics under single-frequency excitation. The main scenarios of transition to chaos as the result of the destruction of two-frequency and three-frequency quasi-periodic oscillations are clarified.

D. M. Vavriv; I. Iu. Chernyshov

1990-01-01

42

Stochastic resonance in collective exciton-polariton excitations inside a GaAs microcavity.  

PubMed

We report the first observation of stochastic resonance in confined exciton polaritons. We evidence this phenomena by tracking the polaritons behavior through two stochastic resonance quantifiers namely the spectral magnification factor and the signal-to-noise ratio. The evolution of the stochastic resonance in the function of the modulation amplitude of the periodic excitation signal is studied. Our experimental observations are well reproduced by numerical simulations performed in the framework of the Gross-Pitaevskii equation under stochastic perturbation. PMID:25126934

Abbaspour, H; Trebaol, S; Morier-Genoud, F; Portella-Oberli, M T; Deveaud, B

2014-08-01

43

Stochastic Resonance in Collective Exciton-Polariton Excitations inside a GaAs Microcavity  

NASA Astrophysics Data System (ADS)

We report the first observation of stochastic resonance in confined exciton polaritons. We evidence this phenomena by tracking the polaritons behavior through two stochastic resonance quantifiers namely the spectral magnification factor and the signal-to-noise ratio. The evolution of the stochastic resonance in the function of the modulation amplitude of the periodic excitation signal is studied. Our experimental observations are well reproduced by numerical simulations performed in the framework of the Gross-Pitaevskii equation under stochastic perturbation.

Abbaspour, H.; Trebaol, S.; Morier-Genoud, F.; Portella-Oberli, M. T.; Deveaud, B.

2014-08-01

44

Vibrational and stochastic resonances in two coupled overdamped anharmonic oscillators  

E-print Network

We study the overdamped version of two coupled anharmonic oscillators under the influence of both low- and high-frequency forces respectively and a Gaussian noise term added to one of the two state variables of the system. The dynamics of the system is first studied in the presence of both forces separately without noise. In the presence of only one of the forces, no resonance behaviour is observed, however, hysteresis happens there. Then the influence of the high-frequency force in the presence of a low-frequency, i.e. biharmonic forcing, is studied. Vibrational resonance is found to occur when the amplitude of the high-frequency force is varied. The resonance curve resembles a stochastic resonance-like curve. It is maximum at the value of $g$ at which the orbit lies in one well during one half of the drive cycle of the low-frequency force and in the other for the remaining half cycle. Vibrational resonance is characterized using the response amplitude and mean residence time. We show the occurrence of stochastic resonance behaviour in the overdamped system by replacing the high-frequency force by Gaussian noise. Similarities and differences between both types of resonance are presented.

V. M. Gandhimathi; S. Rajasekar; J. Kurths

2006-11-10

45

Stochastic resonance of vortices in a washboard pinning potential  

NASA Astrophysics Data System (ADS)

In a bistable potential at low temperatures, stochastic resonance can be characterized as a synchronization effect of the hopping mechanism induced by an external periodic stimulus, where synchronization attains a maximum by fine-tuning the forcing frequency close to the relevant switching rate. In this work, we theoretically investigate the nonlinear single-vortex dynamics in a tilted cosine (multistable) washboard pinning potential at nonzero temperature in the presence of dc and ac currents of arbitrary amplitudes and frequency. The conditions for stochastic resonance to appear are derived on the basis of the exact solution of the corresponding Langevin equation for non-interacting vortices in terms of a matrix continued fraction. The nonlinear ac voltage response is analyzed as a function of temperature, dc bias, ac amplitude and frequency, with particular focus on the amplification of the external harmonic signal and its conversion to the third harmonics of the input frequency.

Shklovskij, Valerij A.; Dobrovolskiy, Oleksandr V.

2014-08-01

46

Stochastic resonance in psychophysics and in animal behavior  

Microsoft Academic Search

.  ?A recent analysis of the energy detector model in sensory psychophysics concluded that stochastic resonance does not occur\\u000a in a measure of signal detectability (d?), but can occur in a percent-correct measure of performance as an epiphenomenon of nonoptimal criterion placement [Tougaard\\u000a (2000) Biol Cybern 83: 471–480]. When generalized to signal detection in sensory systems in general, this conclusion is

Lawrence M. Ward; Alexander Neiman; Frank Moss

2002-01-01

47

Escape process and stochastic resonance under noise intensity fluctuation  

NASA Astrophysics Data System (ADS)

We study the effects of noise intensity fluctuations on the stationary and dynamical properties of an overdamped Langevin model with a bistable potential and external periodical driving force. We calculated the stationary distributions, mean-first passage time (MFPT) and the spectral amplification factor using a complete set expansion (CSE) technique. We found resonant activation (RA) and stochastic resonance (SR) phenomena in the system under investigation. Moreover, the strength of RA and SR phenomena exhibit non-monotonic behavior and their trade-off relation as a function of the squared variation coefficient of the noise intensity process. The reliability of CSE is verified with Monte Carlo simulations.

Hasegawa, Yoshihiko; Arita, Masanori

2011-09-01

48

Thermal enhancement and stochastic resonance of polaron ratchets.  

PubMed

We study the ratchet drift of large polarons (solitons) in molecular diatomic chains induced by unbiased time periodic electric fields at nonzero temperature below its critical value. We show that, at a nonzero temperature, the critical value of the intensity of the electric field above which the ratchet phenomenon takes place is lower than at zero temperature for the same frequency of the field. We show that there is a range of temperatures for which the polaron drift is larger than that at zero temperature. We also show that temperature decreases the value of the lowest critical period of the field. And, finally, we demonstrate that there is a stochastic resonance in a polaron ratchet, namely that there is an optimal temperature at which the polaron drift is a maximum. The values of the stochastic resonance temperature, the lowest critical values of the field intensity, and its period depend on various parameters of the system and, in particular, on the anisotropy of the chain parameters. This temperature induced decrease of the critical value of the field intensity and its period, as well as the stochastic resonance itself, may be important for practical applications of the ratchet phenomenon in systems involving conducting polymers and other low-dimensional materials. They may also be important in some biological macromolecules where the ratchet phenomenon could take place in biomotors and energy and/or charge transport. PMID:25019849

Brizhik, L S; Eremko, A A; Piette, B M A G; Zakrzewski, W J

2014-06-01

49

Stochastic resonance in feedforward acupuncture networks  

NASA Astrophysics Data System (ADS)

Effects of noises and some other network properties on the weak signal propagation are studied systematically in feedforward acupuncture networks (FFN) based on FitzHugh-Nagumo neuron model. It is found that noises with medium intensity can enhance signal propagation and this effect can be further increased by the feedforward network structure. Resonant properties in the noisy network can also be altered by several network parameters, such as heterogeneity, synapse features, and feedback connections. These results may also provide a novel potential explanation for the propagation of acupuncture signal.

Qin, Ying-Mei; Wang, Jiang; Men, Cong; Deng, Bin; Wei, Xi-Le; Yu, Hai-Tao; Chan, Wai-Lok

2014-10-01

50

Quantum stochastic resonance in the strong-field limit and Nancy Makri1,2  

E-print Network

resonance was observed when the driving frequency approaches fractional values of the static detuning energyQuantum stochastic resonance in the strong-field limit Ke Dong1 and Nancy Makri1,2 1 Departments of the quantum stochastic resonance phenomenon outside the weak-field regime. DOI: 10.1103/PhysRevA.70

Makri, Nancy

51

Neural mechanism for binaural pitch perception via ghost stochastic resonance.  

PubMed

We present a physiologically plausible binaural mechanism for the perception of the pitch of complex sounds via ghost stochastic resonance. In this scheme, two neurons are driven by noise and a different periodic signal each (with frequencies f(1)=kf(0) and f(2)=(k+1)f(0), where k>1), and their outputs (plus noise) are applied synaptically to a third neuron. Our numerical results, using the Morris-Lecar neuron model with chemical synapses explicitly considered, show that intermediate noise levels enhance the response of the third neuron at frequencies close to f(0), as in the cases previously described of ghost resonance. For the case of an inharmonic combination of inputs (f(1)=kf(0)+Deltaf and f(2)=(k+1)f(0)+Deltaf) noise is also seen to enhance the rates of most probable spiking for the third neuron at a frequency f(r)=f(0)+[Deltaf(k+12)]. In addition, we show that similar resonances can be observed as a function of the synaptic time constant. The suggested ghost-resonance-based stochastic mechanism can thus arise either at the peripheral level or at a higher level of neural processing in the perception of pitch. PMID:16035898

Balenzuela, Pablo; García-Ojalvo, Jordi

2005-06-01

52

Vestibular experiments  

NASA Technical Reports Server (NTRS)

Spacelab experiments designed to investigate space motion sickness, any associated changes in otolith-mediated responses occurring during weightlessness, and the carryover of any such changes to postflight conditions are described. The experiments aimed at assessing otolithic responses in space are intended to clarify presumed alterations in vestibular function during weightlessness. Vestibular function will be investigated at several levels: vestibulo-ocular reflexes, vestibulo-spinal pathways, cortical functions involving perception of motion and spatial orientation, visual vestibular interaction, and motion sickness susceptibility. A second major objective relates to space motion sickness and man's well-being and productivity in space.

Young, L. R.

1981-01-01

53

Coherence resonance and stochastic resonance in directionally coupled rings  

NASA Astrophysics Data System (ADS)

In coupled systems, symmetry plays an important role for the collective dynamics. We investigate the dynamical response to noise with and without weak periodic modulation for two classes of ring systems. Each ring system consists of unidirectionally coupled bistable elements but in one class, the number of elements is even while in the other class the number is odd. Consequently, the rings without forcing show at a certain coupling strength, either ordering (similar to anti-ferromagnetic chains) or auto-oscillations. Analysing the bifurcations and fixed points of the two ring classes enables us to explain the dynamical response measured to noise and weak modulation. Moreover, by analysing a simplified model, we demonstrate that the response is universal for systems having a directional component in their stochastic dynamics in phase space around the origin.

Werner, Johannes Peter; Benner, Hartmut; Florio, Brendan James; Stemler, Thomas

2011-11-01

54

Stochastic resonance in an over-damped linear oscillator  

NASA Astrophysics Data System (ADS)

For an over-damped linear system subjected to both parametric excitation of colored noise and external excitation of periodically modulated noise, and in the case that the cross-correlation intensity between noises is a time-periodic function, we study the stochastic resonance (SR) in this paper. Using the Shapiro—Loginov formula, we acquire the exact expressions of the first-order and the second-order moments. By the stochastic averaging method, we obtain the analytical expression of the output signal-to-noise ratio (SNR). Meanwhile, we discuss the evolutions of the SNR with the signal frequency, noise intensity, correlation rate of noise, time period, and modulation frequency. We find a new bona fide SR. The evolution of the SNR with the signal frequency presents periodic oscillation, which is not observed in a conventional linear system. We obtain the conventional SR of the SNR with the noise intensity and the correlation rate of noise. We also obtain the SR in a wide sense, in which the evolution of the SNR with time period modulation frequency presents periodic oscillation. We find that the time-periodic modulation of the cross-correlation intensity between noises diversifies the stochastic resonance phenomena and makes this system possess richer dynamic behaviors.

Lin, Li-Feng; Tian, Yan; Ma, Hong

2014-08-01

55

Cyclotron resonance effects on stochastic acceleration of light ionospheric ions  

NASA Technical Reports Server (NTRS)

The production of energetic ions with conical pitch angle distributions along the auroral field lines is a subject of considerable current interest. There are several theoretical treatments showing the acceleration (heating) of the ions by ion cyclotron waves. The quasi-linear theory predicts no acceleration when the ions are nonresonant. In the present investigation, it is demonstrated that the cyclotron resonances are not crucial for the transverse acceleration of ions by ion cyclotron waves. It is found that transverse energization of ionospheric ions, such as He(+), He(++), O(++), and O(+), is possible by an Electrostatic Hydrogen Cyclotron (EHC) wave even in the absence of cyclotron resonance. The mechanism of acceleration is the nonresonant stochastic heating. However, when there are resonant ions both the total energy gain and the number of accelerated ions increase with increasing parallel wave number.

Singh, N.; Schunk, R. W.; Sojka, J. J.

1982-01-01

56

Stochastic Resonance with Colored Noise for Neural Signal Detection  

PubMed Central

We analyze signal detection with nonlinear test statistics in the presence of colored noise. In the limits of small signal and weak noise correlation, the optimal test statistic and its performance are derived under general conditions, especially concerning the type of noise. We also analyze, for a threshold nonlinearity–a key component of a neural model, the conditions for noise-enhanced performance, establishing that colored noise is superior to white noise for detection. For a parallel array of nonlinear elements, approximating neurons, we demonstrate even broader conditions allowing noise-enhanced detection, via a form of suprathreshold stochastic resonance. PMID:24632853

Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

2014-01-01

57

Suprathreshold stochastic resonance and maximizing network for watermark detection  

NASA Astrophysics Data System (ADS)

We propose a novel method that improves watermark detection performance, based on suprathreshold stochastic resonance (SSR) with a maximizing network. The detection performance is measured in terms of correlation. The proposed method has been tested on different gray-scale images, and we found that an original image is not required for watermark detection, so this method is blind. We improved the correlation between an original watermark and the SSR with maximizing network-based discrete wavelet transform coefficients of the watermarked image. Our experimental results have been compared with the different existing techniques and were found superior in terms of correlation and ratio of correlation to threshold.

Jha, Rajib Kumar; Biswas, Prabir Kumar; Gupta, Bhupendra; Mishra, Deepak

2012-01-01

58

Stochastic Resonance for a SQUID with Dichotomous Resistance  

NASA Astrophysics Data System (ADS)

We investigate the response to the ac current for a superconducting quantum interference device (SQUID) with a dichotomous resistance. It is shown that, for some suitably selected parameters' values, stochastic resonance appears for the amplitude of the stationary average voltage of the SQUID versus the correlation time of the dichotomous noise. Our result can provide some useful insights for the investigation of the response of the SQUID (especially for the ones with the nano junctions) to the temporal-periodic signal (including the input ac current, the irradiation microwave, the detected temporal-periodic signal, and the added ac voltage).

Li, Jing-Hui

2014-03-01

59

Stochastic resonance with colored noise for neural signal detection.  

PubMed

We analyze signal detection with nonlinear test statistics in the presence of colored noise. In the limits of small signal and weak noise correlation, the optimal test statistic and its performance are derived under general conditions, especially concerning the type of noise. We also analyze, for a threshold nonlinearity-a key component of a neural model, the conditions for noise-enhanced performance, establishing that colored noise is superior to white noise for detection. For a parallel array of nonlinear elements, approximating neurons, we demonstrate even broader conditions allowing noise-enhanced detection, via a form of suprathreshold stochastic resonance. PMID:24632853

Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

2014-01-01

60

Dim small target detection based on stochastic resonance  

NASA Astrophysics Data System (ADS)

Dim small target detection, which is characterized by complex background and low Signal-to-Noise Ratio (SNR), is critical for many applications. Traditional detection algorithms assume that noise is not useful for detecting targets and try to remove the noise to improve SNR of images using various filtering techniques. In this paper, we introduce a detection algorithm based on Stochastic Resonance (SR) where stochastic resonance is used to enhance the dim small targets. Our intuition is that SR can achieve the target enhancement in the presence of noise. Adaptive Least Mean Square (ALMS) filtering is first adopted to estimate the background, and the clutter is suppressed by subtracting the estimated background image from the source image. Adaptive SR (ASR) method is then employed to enhance the target and improve the SNR of the image containing the target and noise. ASR tunes and adds the optimal noise intensity to increase the power of the targets and therefore improve the SNR of the image. Several experiments on synthetic and natural images are conducted to evaluate our proposed algorithm. The results demonstrate the effectiveness of our algorithm.

Sang, Nong; Wang, Ruolin; Gan, Haitao; Du, Jian; Tang, Qiling

2013-03-01

61

Planetary gearbox fault diagnosis using an adaptive stochastic resonance method  

NASA Astrophysics Data System (ADS)

Planetary gearboxes are widely used in aerospace, automotive and heavy industry applications due to their large transmission ratio, strong load-bearing capacity and high transmission efficiency. The tough operation conditions of heavy duty and intensive impact load may cause gear tooth damage such as fatigue crack and teeth missed etc. The challenging issues in fault diagnosis of planetary gearboxes include selection of sensitive measurement locations, investigation of vibration transmission paths and weak feature extraction. One of them is how to effectively discover the weak characteristics from noisy signals of faulty components in planetary gearboxes. To address the issue in fault diagnosis of planetary gearboxes, an adaptive stochastic resonance (ASR) method is proposed in this paper. The ASR method utilizes the optimization ability of ant colony algorithms and adaptively realizes the optimal stochastic resonance system matching input signals. Using the ASR method, the noise may be weakened and weak characteristics highlighted, and therefore the faults can be diagnosed accurately. A planetary gearbox test rig is established and experiments with sun gear faults including a chipped tooth and a missing tooth are conducted. And the vibration signals are collected under the loaded condition and various motor speeds. The proposed method is used to process the collected signals and the results of feature extraction and fault diagnosis demonstrate its effectiveness.

Lei, Yaguo; Han, Dong; Lin, Jing; He, Zhengjia

2013-07-01

62

A neuron model of stochastic resonance using rectangular pulse trains.  

PubMed

Stochastic resonance (SR) is the enhanced representation of a weak input signal by the addition of an optimal level of broadband noise to a nonlinear (threshold) system. Since its discovery in the 1980s the domain of input signals shown to be applicable to SR has greatly expanded, from strictly periodic inputs to now nearly any aperiodic forcing function. The perturbations (noise) used to generate SR have also expanded, from white noise to now colored noise or vibrational forcing. This study demonstrates that a new class of perturbations can achieve SR, namely, series of stochastically generated biphasic pulse trains. Using these pulse trains as 'noise' we show that a Hodgkin Huxley model neuron exhibits SR behavior when detecting weak input signals. This result is of particular interest to neuroscience because nearly all artificial neural stimulation is implemented with square current or voltage pulses rather than broadband noise, and this new method may facilitate the translation of the performance gains achievable through SR to neural prosthetics. PMID:25186655

Danziger, Zachary; Grill, Warren M

2015-02-01

63

Stochastic resonance in a discrete neuron with time delay and two different modulation signals  

NASA Astrophysics Data System (ADS)

Stochastic resonance in an excitable neuron based on the Rulkov map with noise, delay feedback, low-frequency signal and high-frequency signal is investigated numerically. The results show that there exist an optimal noise intensity, optimal time delay and optimal amplitude of the high-frequency signal at which the phase synchronisation between the low-frequency input signal and the output signal is the best. The Fourier coefficient is calculated to measure the stochastic resonance. It is found that the existence of a maximum in the Q-\\tau , Q-B and Q-D plots is the identifying characteristic of the stochastic resonance phenomenon.

Wang, Can Jun; Li Yang, Ke; Xian Qu, Shi

2014-10-01

64

Reconstructing signals via stochastic resonance generated by photorefractive two-wave mixing bistability.  

PubMed

Stochastic resonance is theoretically investigated in an optical bistable system, which consists of a unidirectional ring cavity and a photorefractive two-wave mixer. It is found that the output properties of stochastic resonance are mainly determined by the applied noise, the crystal length and the applied electric field. The influences of these parameters on the stochastic resonance are also numerically analyzed via cross-correlation, which offers general guidelines for the optimization of recovering noise-hidden signals. A cross-correlation gain of 4 is obtained by optimizing these parameters. This provides a general method for reconstructing signals in nonlinear communications systems. PMID:24663745

Cao, Guangzhan; Liu, Hongjun; Li, Xuefeng; Huang, Nan; Sun, Qibing

2014-02-24

65

On square-wave-driven stochastic resonance for energy harvesting in a bistable system  

NASA Astrophysics Data System (ADS)

Stochastic resonance is a physical phenomenon through which the throughput of energy within an oscillator excited by a stochastic source can be boosted by adding a small modulating excitation. This study investigates the feasibility of implementing square-wave-driven stochastic resonance to enhance energy harvesting. The motivating hypothesis was that such stochastic resonance can be efficiently realized in a bistable mechanism. However, the condition for the occurrence of stochastic resonance is conventionally defined by the Kramers rate. This definition is inadequate because of the necessity and difficulty in estimating white noise density. A bistable mechanism has been designed using an explicit analytical model which implies a new approach for achieving stochastic resonance in the paper. Experimental tests confirm that the addition of a small-scale force to the bistable system excited by a random signal apparently leads to a corresponding amplification of the response that we now term square-wave-driven stochastic resonance. The study therefore indicates that this approach may be a promising way to improve the performance of an energy harvester under certain forms of random excitation.

Su, Dongxu; Zheng, Rencheng; Nakano, Kimihiko; Cartmell, Matthew P.

2014-11-01

66

Stochastic resonance for information flows on hierarchical networks  

NASA Astrophysics Data System (ADS)

A simple model of information flows represented by package delivery on networks with hierarchical structures is considered. The packages should be transferred from one network node to another and the delivery process is influenced by two types of noise. The first type of noise is related to a partially false knowledge of network topology (topological noise), i.e. membership of nodes in communities in a shipping algorithm include a number of errors corresponding to a random rewiring of a fraction of network links. The second type of noise (dynamical noise) is related to a diffusive part in packet dynamics, i.e. package paths do not follow from completely deterministic rules. In the case of a pure topological noise and in the case of combination of both types of noises, we observe a resonance-like phenomenon for communication efficiency. The system performance measured as a fraction of packages that are delivered in a certain time period or as an inverse of time of a package delivery is maximal for intermediate levels of noise. This effect resembles the phenomenon of stochastic resonance that exists in many complex systems where a noise can enhance the information transfer.

Czaplicka, Agnieszka; Ho?yst, Janusz A.; Sloot, Peter M. A.

2013-09-01

67

Stochastic resonance via switching between the two stable limit cycles on a cylinder  

NASA Astrophysics Data System (ADS)

This paper deals with the determination of stochastic resonance (SR) in a driven bistable potential based on an embedding-based description in terms of an autonomous system of stochastic equations. It points out a criterion for SR on the basis of the relative position of limit cycles of the deterministic system.

Qian, Min; Zhang, Xue-Juan

2002-01-01

68

Stochastic resonance in bistable spin-crossover compounds with light-induced transitions  

NASA Astrophysics Data System (ADS)

This article presents a theoretical prediction of stochastic resonance in spin-crossover materials. The analysis of stochastic resonance phenomenon in a spin-crossover system is performed in the framework of the phenomenological kinetic model with light-induced transition described by dynamical potential in terms of the Lyapunov functions. By using numerical simulation of stochastic trajectories with white- and colored-noise action, the evaluation of stochastic resonance is carried out by signal-to-noise ratio of the system output. The corresponding signal-to-noise ratio features a two-peak behavior which is related to the asymmetric shape of the dynamic potential. For the case of the Ornstein-Uhlenbeck process, the variations of resonance condition with respect to different autocorrelation times are additionally studied.

Gudyma, Iurii; Maksymov, Artur; Dimian, Mihai

2014-11-01

69

Stochastic resonance in bistable spin-crossover compounds with light-induced transitions.  

PubMed

This article presents a theoretical prediction of stochastic resonance in spin-crossover materials. The analysis of stochastic resonance phenomenon in a spin-crossover system is performed in the framework of the phenomenological kinetic model with light-induced transition described by dynamical potential in terms of the Lyapunov functions. By using numerical simulation of stochastic trajectories with white- and colored-noise action, the evaluation of stochastic resonance is carried out by signal-to-noise ratio of the system output. The corresponding signal-to-noise ratio features a two-peak behavior which is related to the asymmetric shape of the dynamic potential. For the case of the Ornstein-Uhlenbeck process, the variations of resonance condition with respect to different autocorrelation times are additionally studied. PMID:25493767

Gudyma, Iurii; Maksymov, Artur; Dimian, Mihai

2014-11-01

70

Impact of time delays on stochastic resonance in an ecological system describing vegetation  

NASA Astrophysics Data System (ADS)

In this paper, we investigate the stochastic resonance phenomenon in a vegetation ecological system with time delay, at which the vegetation dynamics is assumed to be disturbed by both intrinsic and extrinsic noises. The signal-to-noise ratio is calculated when a weak periodic signal is added to the system. The impacts of time delay ? and correlation strength k between two noises on the signal-to-noise ratio are discussed, respectively. Our research results show that: (i) the increase of ? or k can enhance the stochastic resonance in the signal-to-noise ratio as a function of intrinsic noise strength ?; (ii) on the contrary, the increase of ? or k can weaken the stochastic resonance in the signal-to-noise ratio as a function of extrinsic noise strength D; and (iii) the increase of ? can lead to double stochastic resonance phenomenon in the signal-to-noise ratio as a function of k.

Han, Qinglin; Yang, Tao; Zeng, Chunhua; Wang, Hua; Liu, Zhiqiang; Fu, Yunchang; Zhang, Chun; Tian, Dong

2014-08-01

71

Vestibular disease: diseases causing vestibular signs.  

PubMed

Having determined whether a patient has central or peripheral vestibular disease, clinicians must then determine what diseases are likely to result in such a presentation. This article describes the more common diseases causing vestibular disease in dogs and cats. Having formulated a list of potential causes of vestibular disease, clinicians should proceed through a systematic investigation to diagnose the underlying condition. A companion article describes the anatomy, physiology, and clinical signs associated with vestibular disease. PMID:22847321

Lowrie, Mark

2012-07-01

72

Vestibular Schwannoma  

PubMed Central

Vestibular schwannomas (VS) commonly are limited to the internal auditory canal (IAC) and cerebellopontine angle. Extension to labyrinth is less frequent, and involvement of the middle ear or external acoustic canal (EAC) is very rare. In this report we present the case of a 41-year-old woman with a VS, which recurred after a previous surgical removal 4 years before. The tumor involved the IAC, cochlea, vestibule, semicircular canals, cavum tympani, mastoid cells, and EAC. Total removal of the tumor was achieved by a transotic approach, without neurological sequela. ImagesFigure 1Figure 2Figure 3Figure 4 PMID:17171129

Carreńo, Marcos; Llorente, José L.; Suárez, Carlos

1999-01-01

73

Effects of time delay on the stochastic resonance in small-world neuronal networks.  

PubMed

The effects of time delay on stochastic resonance in small-world neuronal networks are investigated. Without delay, an intermediate intensity of additive noise is able to optimize the temporal response of the neural system to the subthreshold periodic signal imposed on all neurons constituting the network. The time delay in the coupling process can either enhance or destroy stochastic resonance of neuronal activity in the small-world network. In particular, appropriately tuned delays can induce multiple stochastic resonances, which appear intermittently at integer multiples of the oscillation period of weak external forcing. It is found that the delay-induced multiple stochastic resonances are most efficient when the forcing frequency is close to the global-resonance frequency of each individual neuron. Furthermore, the impact of time delay on stochastic resonance is largely independent of the small-world topology, except for resonance peaks. Considering that information transmission delays are inevitable in intra- and inter-neuronal communication, the presented results could have important implications for the weak signal detection and information propagation in neural systems. PMID:23556965

Yu, Haitao; Wang, Jiang; Du, Jiwei; Deng, Bin; Wei, Xile; Liu, Chen

2013-03-01

74

Improving Sensorimotor Adaptation Following Long Duration Space Flight by Enhancing Vestibular Information Transfer  

NASA Technical Reports Server (NTRS)

Crewmember adapted to the microgravity state may need to egress the vehicle within a few minutes for safety and operational reasons after gravitational transitions. The transition from one sensorimotor state to another consists of two main mechanisms: strategic and plastic-adaptive and have been demonstrated in astronauts returning after long duration space flight. Strategic modifications represent "early adaptation" - immediate and transitory changes in control that are employed to deal with short-term changes in the environment. If these modifications are prolonged then plastic-adaptive changes are evoked that modify central nervous system function, automating new behavioral responses. More importantly, this longer term adaptive recovery mechanism was significantly associated with their strategic ability to recover on the first day after return to Earth G. We are developing a method based on stochastic resonance to enhance information transfer by improving the brain's ability to detect vestibular signals (Vestibular Stochastic Resonance, VSR) especially when combined with balance training exercises such as sensorimotor adaptability (SA) training for rapid improvement in functional skill, for standing and mobility. This countermeasure to improve detection of vestibular signals is a stimulus delivery system that is wearable/portable providing low imperceptible levels of white noise based binaural bipolar electrical stimulation of the vestibular system (stochastic vestibular stimulation). To determine efficacy of vestibular stimulation on physiological and perceptual responses during otolith-canal conflicts and dynamic perturbations we have conducted a series of studies: We have shown that imperceptible binaural bipolar electrical stimulation of the vestibular system across the mastoids enhances balance performance in the mediolateral (ML) plane while standing on an unstable surface. We have followed up on the previous study showing VSR stimulation improved balance performance in both ML and anteroposterior planes while stimulating in the ML axis only. We have shown the efficacy of VSR stimulations on enhancing physiological and perceptual responses of whole-body orientation during low frequency perturbations (0.1 Hz) on the ocular motor system using a variable radius centrifuge on both physiological (using eye movements) and perceptual responses (using a joystick) to track imposed oscillations. The variable radius centrifuge provides a selective tilting sensation that is detectable only by the otolith organs providing conflicting information from the canal organs of the vestibular system (intra-vestibular conflict). These results indicate that VSR can improve performance in sensory conflict scenarios like that experienced during space flight. We have showed the efficacy of VSR stimulation to improve balance and locomotor control on subjects exposed to continuous, sinusoidal lateral motion of the support surface while walking on a treadmill while viewing perceptually matched linear optic flow. We have shown the safety of short term continuous use of up to 4 hours of VSR stimulation and its efficacy in improving balance and locomotor function in Parkinson's Disease patients. This technique for improving vestibular signal detection may thus provide additional information to improve strategic abilities. We hypothesize that VSR stimulation will act synergistically with SA training to improve adaptability by increased utilization of vestibular information and therefore serve to optimize and personalize the SA countermeasure prescription. This forms the basis of its usefulness both as a training modality and further help in significantly reducing the number of days required to recover functional performance to preflight levels after long duration space flight.

Mulavara, A. P.; Kofman, I. S.; De Dios, Y. E; Galvan, R.; Goel, R.; Miller, C.; Peters, B.; Cohen, H. S.; Jeevarajan, J.; Reschke, M.; Wood, S.; Bergquist, F.; Seidler, R. D.; Bloomberg, J. J.

2014-01-01

75

Coherent and stochastic contributions of compound resonances in atomic processes: electron recombination, photoionization and scattering  

E-print Network

In open-shell atoms and ions, processes such as photoionization, combination (Raman) scattering, electron scattering and recombination, are often mediated by many-electron compound resonances. We show that their interference (neglected in independent-resonance approximation) leads to a coherent contribution, which determines the energy-averaged total cross sections of electron- and photon-induced reactions found from the optical theorem. On the other hand, the partial cross sections (e.g., electron recombination, combination photon scattering) are dominated by the stochastic contributions. Thus, the optical theorem provides a link between the stochastic and coherent contributions of the compound resonances.

V. V. Flambaum; M. G. Kozlov; G. F. Gribakin

2014-04-16

76

Feasibility of energy harvesting from a rotating tire based on the theory of stochastic resonance  

NASA Astrophysics Data System (ADS)

Recently the use of nonlinear bi-stable micro-electro mechanical systems (MEMS) to achieve automobile tire vibration power generation has made some progress. However, the theory of stochastic resonance has not been successfully applied to automobile tires, which can produce a larger vibrational response than for a typical resonance while inputting a weak periodic force and noise excitation into a nonlinear bi-stable system. Hence, in this paper, in view of the principle of stochastic resonance, a new model is derived by positioning a magnetic end mass attached to a cantilever beam and another permanent magnet with the same polarity on the frame. Due to the road noise excitation along with the periodic force inputted to the mechanism, whether the phenomenon of stochastic resonance can happen will be discussed. Meanwhile, on the basis of Kramers rate and duffing equations the preliminary experimental device is also designed.

Zhang, Y.; Zheng, R.; Nakano, K.

2014-11-01

77

What Is Stochastic Resonance? Definitions, Misconceptions, Debates, and Its Relevance to Biology  

PubMed Central

Stochastic resonance is said to be observed when increases in levels of unpredictable fluctuations—e.g., random noise—cause an increase in a metric of the quality of signal transmission or detection performance, rather than a decrease. This counterintuitive effect relies on system nonlinearities and on some parameter ranges being “suboptimal”. Stochastic resonance has been observed, quantified, and described in a plethora of physical and biological systems, including neurons. Being a topic of widespread multidisciplinary interest, the definition of stochastic resonance has evolved significantly over the last decade or so, leading to a number of debates, misunderstandings, and controversies. Perhaps the most important debate is whether the brain has evolved to utilize random noise in vivo, as part of the “neural code”. Surprisingly, this debate has been for the most part ignored by neuroscientists, despite much indirect evidence of a positive role for noise in the brain. We explore some of the reasons for this and argue why it would be more surprising if the brain did not exploit randomness provided by noise—via stochastic resonance or otherwise—than if it did. We also challenge neuroscientists and biologists, both computational and experimental, to embrace a very broad definition of stochastic resonance in terms of signal-processing “noise benefits”, and to devise experiments aimed at verifying that random variability can play a functional role in the brain, nervous system, or other areas of biology. PMID:19562010

McDonnell, Mark D.; Abbott, Derek

2009-01-01

78

Stochastic charging of dust grains in planetary rings: Diffusion rates and their effects on Lorentz resonances  

NASA Technical Reports Server (NTRS)

Dust grains in planetary rings acquire stochastically fluctuating electric charges as they orbit through any corotating magnetospheric plasma. Here we investigate the nature of this stochastic charging and calculate its effect on the Lorentz resonance (LR). First we model grain charging as a Markov process, where the transition probabilities are identified as the ensemble-averaged charging fluxes due to plasma pickup and photoemission. We determine the distribution function P(t;N), giving the probability that a grain has N excess charges at time t. The autocorrelation function tau(sub q) for the strochastic charge process can be approximated by a Fokker-Planck treatment of the evolution equations for P(t; N). We calculate the mean square response to the stochastic fluctuations in the Lorentz force. We find that transport in phase space is very small compared to the resonant increase in amplitudes due to the mean charge, over the timescale that the oscillator is resonantly pumped up. Therefore the stochastic charge variations cannot break the resonant interaction; locally, the Lorentz resonance is a robust mechanism for the shaping of etheral dust ring systems. Slightly stronger bounds on plasma parameters are required when we consider the longer transit times between Lorentz resonances.

Schaffer, L.; Burns, J. A.

1995-01-01

79

Stochastic Resonance Improves Broadband Encoding in the Cricket Cercal System.  

NASA Astrophysics Data System (ADS)

In any physical or biological system a certain amount of environmental noise is unavoidable, and the information therein irrelevant to the organism. Traditionally in signal analysis noise is considered detrimental to the process of signal encoding, and merely a necessary evil to be avoided. It has been observed recently, however, that in some nonlinear systems power from random input noise actually improves the output signal-to-noise ratio (SNR) over a limited operating range, particularly near threshold. This effect is known as stochastic resonance (SR). By taking advantage of SR during the neural encoding process, a cell can optimize its information flow properties. Previous experimental work in SR has investigated only the coding of sinusoidal signals embedded in a broadband white noise background. In this work we demonstrate SR for not only the sine wave case, but also for extended bandwidth stimuli in the presence of white noise, and for cases in which the signal and white noise background frequency spectra are completely non-overlapping. We have investigated the effects of noise on information transfer in the cricket cercal system, a mechanosensory system sensitive to small near-field air particle disturbances, by presenting known wind stimuli to the cricket through audio speakers in a controlled environment along with varying levels of uncorrelated white noise background air current. Spike trains from the second layer of neuronal processing, the primary sensory interneurons, were recorded with intracellular electrodes with the signal and noise presented along the cell's preferred direction. Through the statistical techniques of Shannon's information theory we quantified the amount of information contained in the elicited spike trains about the signal in the various noise environments, as well as the SNR and other measures of the encoding process. An enhancement of output SNR was observed over the entire frequency operating range of the neurons, for almost an entire order of magnitude of near-threshold signal amplitudes. Additionally, we found that the amount of information about the signal carried, on average, by each spike was INCREASED for small signals when presented with noise - implying that added input noise can, in certain situations, actually improve the accuracy of the encoding process itself.

Levin, Jacob

1996-03-01

80

Acute effects of stochastic resonance whole body vibration  

PubMed Central

AIM: To investigate the acute effects of stochastic resonance whole body vibration (SR-WBV) training to identify possible explanations for preventive effects against musculoskeletal disorders. METHODS: Twenty-three healthy, female students participated in this quasi-experimental pilot study. Acute physiological and psychological effects of SR-WBV training were examined using electromyography of descending trapezius (TD) muscle, heart rate variability (HRV), different skin parameters (temperature, redness and blood flow) and self-report questionnaires. All subjects conducted a sham SR-WBV training at a low intensity (2 Hz with noise level 0) and a verum SR-WBV training at a higher intensity (6 Hz with noise level 4). They were tested before, during and after the training. Conclusions were drawn on the basis of analysis of variance. RESULTS: Twenty-three healthy, female students participated in this study (age = 22.4 ± 2.1 years; body mass index = 21.6 ± 2.2 kg/m2). Muscular activity of the TD and energy expenditure rose during verum SR-WBV compared to baseline and sham SR-WBV (all P < 0.05). Muscular relaxation after verum SR-WBV was higher than at baseline and after sham SR-WBV (all P < 0.05). During verum SR-WBV the levels of HRV were similar to those observed during sham SR-WBV. The same applies for most of the skin characteristics, while microcirculation of the skin of the middle back was higher during verum compared to sham SR-WBV (P < 0.001). Skin redness showed significant changes over the three measurement points only in the middle back area (P = 0.022). There was a significant rise from baseline to verum SR-WBV (0.86 ± 0.25 perfusion units; P = 0.008). The self-reported chronic pain grade indicators of pain, stiffness, well-being, and muscle relaxation showed a mixed pattern across conditions. Muscle and joint stiffness (P = 0.018) and muscular relaxation did significantly change from baseline to different conditions of SR-WBV (P < 0.001). Moreover, muscle relaxation after verum SR-WBV was higher than after sham SR-WBV (P < 0.05). CONCLUSION: Verum SR-WBV stimulated musculoskeletal activity in young healthy individuals while cardiovascular activation was low. Training of musculoskeletal capacity and immediate increase in musculoskeletal relaxation are potential mediators of pain reduction in preventive trials. PMID:24147265

Elfering, Achim; Zahno, Jasmine; Taeymans, Jan; Blasimann, Angela; Radlinger, Lorenz

2013-01-01

81

Amplification of weak signals and stochastic resonance via on-off intermittency with symmetry breaking  

E-print Network

Nonlinear dynamical systems possessing reflection symmetry have an invariant subspace in the phase space. The dynamics within the invariant subspace can be random or chaotic. As a system parameter changes, the motion transverse to the invariant subspace can lose stability, leading to on-off intermittency. Under certain conditions, the bursting behavior is symmetry-breaking. We demonstrate the possibility of observing multiplicative noise(chaos)-induced amplification of weak signal and stochastic resonance via on-off intermittency with symmetry breaking in a general class of symmetrical systems. Differences of this mechanism of stochastic resonance to that in noisy bistable or threshold systems are discussed

Changsong Zhou; C. -H. Lai

2000-05-08

82

Large vestibular aqueduct syndrome.  

PubMed

Large Vestibular Aqueduct Syndrome is a congenital malformation of the temporal bone characterised by early onset of sensorineural hearing loss and vestibular disturbance. Familial large vestibular aqueduct syndrome suggests autosomal recessive or X-linked inheritance and accounts for non-syndromic sensorineural hearing loss in these patients. PMID:16570713

Dipak, S; Prepageran, N; Sazila, A S; Rahmat, O; Raman, R

2005-10-01

83

Broadband neural encoding in the cricket cereal sensory system enhanced by stochastic resonance  

NASA Astrophysics Data System (ADS)

SENSORY systems are often required to detect a small amplitude signal embedded in broadband background noise. Traditionally, ambient noise is regarded as detrimental to encoding accuracy. Recently, however, a phenomenon known as stochastic resonance has been described in which, for systems with a nonlinear threshold, increasing the input noise level can actually improve the output signal-to-noise ratio over a limited range of signal and noise strengths. Previous theoretical and experimental studies of stochastic resonance in physical1-7and biological6-10 systems have dealt exclusively with single-frequency sine stimuli embedded in a broadband noise background. In the past year it has been shown in a theoretical and modelling study that stochastic resonance can be observed with broadband signals11,12. Here we demonstrate that broadband stochastic resonance is manifest in the peripheral layers of neural processing in a simple sensory system, and that it plays a role over a wide range of biologically relevant stimulus parameters. Further, we quantify the functional significance of the phenomenon within the context of signal processing, using information theory.

Levin, Jacob E.; Miller, John P.

1996-03-01

84

Subharmonic stochastic synchronization and resonance in neuronal systems Dante R. Chialvo,1,2,3  

E-print Network

on sensory neurons often have multiple discrete spectral lines, as for example in the cases of human speech. In this paper we analyze the response of a model neuron driven by noise and by a weak signal composed of the sumSubharmonic stochastic synchronization and resonance in neuronal systems Dante R. Chialvo,1

Chialvo, Dante R.

85

Investigations of stochastic resonance in two-terminal device with vanadium dioxide film  

SciTech Connect

The results of stochastic resonance investigation in a nonlinear system, consisting of a microstructure with a polycrystalline vanadium dioxide (VO{sub 2}) film grown on sapphire and resistor in series are reported. Nonlinearity of the system was provided due to insulator-metal phase transition in VO{sub 2}. In the stochastic resonance regime at 100?Hz signal frequency, the transition coefficient of signal-to-noise ratio reached 87 in contrast to 250 for microstructures with VO{sub 2} films grown on silica in our previous investigations. The measured characteristics of microstructures with VO{sub 2} films grown on silica and sapphire substrates were found to be qualitatively similar. For both substrates, a stochastic resonance was observed at threshold switching voltage from insulating to metallic state of VO{sub 2}. For sapphire substrate the output signal-to-noise ratio rose at higher signal frequencies. The stochastic resonance phenomenon in VO{sub 2} films is explained in terms of the monostable damped oscillator model.

Aliev, V. Sh., E-mail: aliev@isp.nsc.ru; Bortnikov, S. G.; Badmaeva, I. A. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, 13 Lavrentyev aven., Novosibirsk 630090 (Russian Federation)

2014-05-28

86

Noise enhancement of information transfer in crayfish mechanoreceptors by stochastic resonance  

Microsoft Academic Search

IN linear information theory, electrical engineering and neurobiology, random noise has traditionally been viewed as a detriment to information transmission. Stochastic resonance (SR) is a nonlinear, statistical dynamics whereby information flow in a multistate system is enhanced by the presence of optimized, random noise1 4. A major consequence of SR for signal reception is that it makes possible substantial improvements

John K. Douglass; Lon Wilkens; Eleni Pantazelou; Frank Moss

1993-01-01

87

Self-tuning and stochastic resonance in a simple threshold system—a filter theory approach  

NASA Astrophysics Data System (ADS)

Fully nonlinear filter theory is applied to a simple threshold system, which plays the role of an observer of input signals from a Brownian dynamical system. Our filtering results are discussed within the frameworks of both stochastic resonance and self-tuning of the threshold values, which gathers a lot of attention in relation to information processing in auditory systems.

Munakata, Toyonori; Hada, Takahiro; Ueda, Michihito

2007-03-01

88

Stochastic resonance and the benefits of noise: from ice ages to crayfish and SQUIDs  

Microsoft Academic Search

Noise in dynamical systems is usually considered a nuisance. But in certain nonlinear systems, including electronic circuits and biological sensory apparatus, the presence of noise can in fact enhance the detection of weak signals. This phenomenon, called stochastic resonance, may find useful application in physical, technological and biomedical contexts.

Kurt Wiesenfeld; Frank Moss

1995-01-01

89

A new look at stochastic resonance enhancement of mammalian auditory information processing  

Microsoft Academic Search

Among the communities of medicine and physiology, it has been long recognized most biological systems can be described as deterministic systems with some added noise (5). Stochastic resonance (SR) in biological systems was originally referred to a situation where a noise at an intermediate level is added to a signal to improve the detection of the signal. It is also

Dawei Hong; Shushuang Man

2009-01-01

90

Ubiquitous Crossmodal Stochastic Resonance in Humans: Auditory Noise Facilitates Tactile, Visual and Proprioceptive Sensations  

Microsoft Academic Search

BackgroundStochastic resonance is a nonlinear phenomenon whereby the addition of noise can improve the detection of weak stimuli. An optimal amount of added noise results in the maximum enhancement, whereas further increases in noise intensity only degrade detection or information content. The phenomenon does not occur in linear systems, where the addition of noise to either the system or the

Eduardo Lugo; Rafael Doti; Jocelyn Faubert; Leslie B. Vosshall

2008-01-01

91

Synchronization and stochastic resonance of the small-world neural network based on the CPG.  

PubMed

According to biological knowledge, the central nervous system controls the central pattern generator (CPG) to drive the locomotion. The brain is a complex system consisting of different functions and different interconnections. The topological properties of the brain display features of small-world network. The synchronization and stochastic resonance have important roles in neural information transmission and processing. In order to study the synchronization and stochastic resonance of the brain based on the CPG, we establish the model which shows the relationship between the small-world neural network (SWNN) and the CPG. We analyze the synchronization of the SWNN when the amplitude and frequency of the CPG are changed and the effects on the CPG when the SWNN's parameters are changed. And we also study the stochastic resonance on the SWNN. The main findings include: (1) When the CPG is added into the SWNN, there exists parameters space of the CPG and the SWNN, which can make the synchronization of the SWNN optimum. (2) There exists an optimal noise level at which the resonance factor Q gets its peak value. And the correlation between the pacemaker frequency and the dynamical response of the network is resonantly dependent on the noise intensity. The results could have important implications for biological processes which are about interaction between the neural network and the CPG. PMID:24808930

Lu, Qiang; Tian, Juan

2014-06-01

92

Stochastic resonance on the transverse displacement of swimmers in an oscillatory shear flow  

NASA Astrophysics Data System (ADS)

Self-propelled microorganisms, such as unicellular algae or bacteria, swim along their director relative to the fluid velocity. Under a steady shear flow the director rotates in close orbit, a periodic structure that is preserved under an oscillatory shear flow. If the shear flow is subjected to small fluctuations produced by small irregularities in the microchannel or by other swimmers nearby, the director dynamics becomes stochastic. Numerical integration of the swimmer motion shows that there is stochastic resonance: The displacement in the vorticity direction is maximized for a finite noise intensity. This transverse displacement resonance is observed when the displacement is coarse grained over several periods, although the director is preferentially oriented along the flow. The resonant noise intensity is proportional to the oscillation frequency and independent of the shear rate. The enhanced displacement can have effects on the transverse diffusion of swimmers and the rheology of the suspension.

Guzmán-Lastra, Francisca; Soto, Rodrigo

2012-09-01

93

The effects of nonlinear series resonance on Ohmic and stochastic heating in capacitive discharges  

SciTech Connect

The flow of electron and ion conduction currents across a nonlinear capacitive sheath to the electrode surface self-consistently sets the dc bias voltage across the sheath. We incorporate these currents into a model of a homogeneous capacitive sheath in order to determine the enhancement of the Ohmic and stochastic heating due to self-excitation of the nonlinear series resonance in an asymmetric capacitive discharge. At lower pressures, the series resonance can enhance both the Ohmic and stochastic heating by factors of 2-4, with the Ohmic heating tending to zero as the pressure decreases. The model was checked, for a particular set of parameters, by a particle-in-cell (PIC) simulation using the homogeneous sheath approximation, giving good agreement. With a self-consistent Child-law sheath, the PIC simulation showed increased heating, as expected, whether the series resonance is important or not.

Lieberman, M. A.; Lichtenberg, A. J.; Kawamura, E. [Department of Electrical Engineering and Computer Science-1770, University of California, Berkeley, California 94720 (United States); Mussenbrock, Thomas; Brinkmann, Ralf Peter [Lehrstuhl fuer Theoretische Elektrotechnik, Ruhr-Universitaet Bochum, D44801 Bochum (Germany)

2008-06-15

94

A digital accelerometer array utilizing suprathreshold stochastic resonance for detection of sub-Brownian noise floor accelerations.  

SciTech Connect

The goal of this LDRD project was to evaluate the possibilities of utilizing Stochastic resonance in micromechanical sensor systems as a means for increasing signal to noise for physical sensors. A careful study of this field reveals that in the case of a single sensing element, stochastic resonance offers no real advantage. We have, however, identified a system that can utilize very similar concepts to stochastic resonance in order to achieve an arrayed sensor system that could be superior to existing technologies in the field of inertial sensors, and could offer a very low power technique for achieving navigation grade inertial measurement units.

Carr, Dustin Wade; Olsson, Roy H.

2004-12-01

95

Stochastic resonance on a modular neuronal network of small-world subnetworks with a subthreshold pacemaker  

NASA Astrophysics Data System (ADS)

We study the phenomenon of stochastic resonance on a modular neuronal network consisting of several small-world subnetworks with a subthreshold periodic pacemaker. Numerical results show that the correlation between the pacemaker frequency and the dynamical response of the network is resonantly dependent on the intensity of additive spatiotemporal noise. This effect of pacemaker-driven stochastic resonance of the system depends extensively on the local and the global network structure, such as the intra- and inter-coupling strengths, rewiring probability of individual small-world subnetwork, the number of links between different subnetworks, and the number of subnetworks. All these parameters play a key role in determining the ability of the network to enhance the noise-induced outreach of the localized subthreshold pacemaker, and only they bounded to a rather sharp interval of values warrant the emergence of the pronounced stochastic resonance phenomenon. Considering the rather important role of pacemakers in real-life, the presented results could have important implications for many biological processes that rely on an effective pacemaker for their proper functioning.

Yu, Haitao; Wang, Jiang; Liu, Chen; Deng, Bin; Wei, Xile

2011-12-01

96

Stochastic resonance in an RF SQUID with shunted ScS junction  

NASA Astrophysics Data System (ADS)

Using a point (superconductor-constriction-superconductor, ScS) contact in a single-Josephson-junction superconducting quantum interference device (RF SQUID) provides stochastic resonance conditions at any arbitrary small value of loop inductance and contact critical current, unlike SQUIDs with more traditional tunnel (superconductor-insulator-superconductor, SIS) junctions. This is due to the unusual potential energy of the ScS RF SQUID which always has a barrier between two wells, thus making the device bistable. This paper presents the results of a numerical simulation of the stochastic dynamics of the magnetic flux in an ScS RF SQUID loop affected by band-limited white Gaussian noise and low-frequency sine signals of small and moderate amplitudes. The difference in stochastic amplification of RF SQUID loops incorporating ScS and SIS junctions is discussed.

Turutanov, O. G.; Golovanevskiy, V. A.; Lyakhno, V. Yu.; Shnyrkov, V. I.

2014-02-01

97

Vestibular Perception following Acute Unilateral Vestibular Lesions  

PubMed Central

Little is known about the vestibulo-perceptual (VP) system, particularly after a unilateral vestibular lesion. We investigated vestibulo-ocular (VO) and VP function in 25 patients with vestibular neuritis (VN) acutely (2 days after onset) and after compensation (recovery phase, 10 weeks). Since the effect of VN on reflex and perceptual function may differ at threshold and supra-threshold acceleration levels, we used two stimulus intensities, acceleration steps of 0.5°/s2 and velocity steps of 90°/s (acceleration 180°/s2). We hypothesised that the vestibular lesion or the compensatory processes could dissociate VO and VP function, particularly if the acute vertiginous sensation interferes with the perceptual tasks. Both in acute and recovery phases, VO and VP thresholds increased, particularly during ipsilesional rotations. In signal detection theory this indicates that signals from the healthy and affected side are still fused, but result in asymmetric thresholds due to a lesion-induced bias. The normal pattern whereby VP thresholds are higher than VO thresholds was preserved, indicating that any ‘perceptual noise’ added by the vertigo does not disrupt the cognitive decision-making processes inherent to the perceptual task. Overall, the parallel findings in VO and VP thresholds imply little or no additional cortical processing and suggest that vestibular thresholds essentially reflect the sensitivity of the fused peripheral receptors. In contrast, a significant VO-VP dissociation for supra-threshold stimuli was found. Acutely, time constants and duration of the VO and VP responses were reduced – asymmetrically for VO, as expected, but surprisingly symmetrical for perception. At recovery, VP responses normalised but VO responses remained shortened and asymmetric. Thus, unlike threshold data, supra-threshold responses show considerable VO-VP dissociation indicative of additional, higher-order processing of vestibular signals. We provide evidence of perceptual processes (ultimately cortical) participating in vestibular compensation, suppressing asymmetry acutely in unilateral vestibular lesions. PMID:23671577

Cousins, Sian; Kaski, Diego; Cutfield, Nicholas; Seemungal, Barry; Golding, John F.; Gresty, Michael; Glasauer, Stefan; Bronstein, Adolfo M.

2013-01-01

98

Stochastic resonance in a single-well anharmonic oscillator with coexisting attractors  

NASA Astrophysics Data System (ADS)

We present a numerical investigation of occurrence of stochastic resonance in a single-well anharmonic oscillator where period doubling and chaotic orbits coexist with a large amplitude periodic orbit for a wide range of values of frequency ? of the external periodic force f sin ?t. Stochastic resonance occurs due to the noise-induced switching between the large amplitude periodic orbit and another coexisting orbit. The signal-to-noise ratio (SNR) is found to be maximum at an optimum value of noise intensity (DMAX) and with ?,DMAX increases while SNR at DMAX decreases linearly in different rates with respect to the coexisting chaotic and periodic attractors. The mean residence times around the two coexisting orbits are not same at D=DMAX.

Arathi, S.; Rajasekar, S.

2014-12-01

99

Effect of syncytium structure of receptor systems on stochastic resonance induced by chaotic potential fluctuation.  

PubMed Central

To study a role of syncytium structure of sensory receptor systems in the detection of weak signals through stochastic resonance, we present a model of a receptor system with syncytium structure in which receptor cells are interconnected by gap junctions. The apical membrane of each cell includes two kinds of ion channels whose gating processes are described by the deterministic model. The membrane potential of each cell fluctuates chaotically or periodically, depending on the dynamical state of collective channel gating. The chaotic fluctuation of membrane potential acts as internal noise for the stochastic resonance. The detection ability of the system increases as the electric conductance between adjacent cells generated by the gap junction increases. This effect of gap junctions arises mainly from the fact that the synchronization of chaotic fluctuation of membrane potential between the receptor cells is strengthened as the density of gap junctions is increased. PMID:9746512

Kashimori, Y; Funakubo, H; Kambara, T

1998-01-01

100

Stochastic Transport Modeling of Resonant Magnetic Perturbations in DIII-D  

SciTech Connect

Three-dimensional two-fluid simulations of heat transport due to resonant magnetic perturbations of tokamaks have been computed by coupling the TRIP3D field line tracing code to the E3D edge transport code. The predicted electron temperature contours follow the new separatrix represented by the perturbed invariant manifold structure of the X-point in qualitative agreement with X-point TV observations. However, preliminary modeling predicts that the resulting stochastic heat transport is greater than that measured in low-collisionality ELM suppression experiments in DIII-D H-mode plasmas. While improved determination of transport coefficients is definitely required, possible explanations include plasma screening of resonant perturbations, invalid treatment of the edge as a fluid, or insufficient understanding of stochastic heat transport.

Joseph, I; Moyer, R A; Evans, T E; Schaffer, M J; Runov, A M; Schneider, R; Kasilov, S V; Groth, M; Fenstermacher, M E

2006-06-01

101

Weak feature extraction of gear fault based on stochastic resonance denoising  

NASA Astrophysics Data System (ADS)

To solve the problem of feature extraction of weak gear fault under strong noise background, an early feature extraction method based on cascaded monostable stochastic resonance (CMSR) system and empirical mode decomposition (EMD) with teager energy operator demodulation was proposed. The model of monostable stochastic resonance expanded the processing range of characteristic frequency of the measured signal, and had a good effect on denoising performance by cascading. Firstly CMSR was employed as the preprocessor to remove noise, then the denoised signal was decomposed into a series of intrinsic mode functions (IMFs) of different scales by EMD, and finally teager energy operator demodulation was applied to obtain amplitudes and frequencies of each effective IMF to extract the weak gear fault feature. Simulation and application results showed that the proposed method could effectively detect the characteristic frequency of gear fault of local damage after the noise reduction by CMSR.

Zhao, Jun; Lai, Xin-huan; Kong, Ming; Guo, Tian-tai

2013-01-01

102

Noise-Induced Entrainment and Stochastic Resonance in Human Brain Waves  

NASA Astrophysics Data System (ADS)

We present the first observation of stochastic resonance (SR) in the human brain's visual processing area. The novel experimental protocol is to stimulate the right eye with a subthreshold periodic optical signal and the left eye with a noisy one. The stimuli bypass sensory organs and are mixed in the visual cortex. With many noise sources present in the brain, higher brain functions, e.g., perception and cognition, may exploit SR.

Mori, Toshio; Kai, Shoichi

2002-05-01

103

Noise-induced entrainment and stochastic resonance in human brain waves.  

PubMed

We present the first observation of stochastic resonance (SR) in the human brain's visual processing area. The novel experimental protocol is to stimulate the right eye with a subthreshold periodic optical signal and the left eye with a noisy one. The stimuli bypass sensory organs and are mixed in the visual cortex. With many noise sources present in the brain, higher brain functions, e.g., perception and cognition, may exploit SR. PMID:12059504

Mori, Toshio; Kai, Shoichi

2002-05-27

104

Effects of time delay on stochastic resonance of the stock prices in financial system  

NASA Astrophysics Data System (ADS)

The effect of time delay on stochastic resonance of the stock prices in finance system was investigated. The time delay is introduced into the Heston model driven by the extrinsic and intrinsic periodic information for stock price. The signal power amplification (SPA) was calculated by numerical simulation. The results indicate that an optimal critical value of delay time maximally enhances the reverse-resonance in the behaviors of SPA as a function of long-run variance of volatility or cross correlation coefficient between noises for both cases of intrinsic and extrinsic periodic information. Moreover, in both cases, being a critical value in the delay time, when the delay time takes value below the critical value, reverse-resonance increases with the delay time increasing, however, when the delay time takes value above the critical value, the reverse-resonance decrease with the delay time increasing.

Li, Jiang-Cheng; Li, Chun; Mei, Dong-Cheng

2014-06-01

105

Friction-induced Resonance of a Stochastic Oscillator  

NASA Astrophysics Data System (ADS)

The influence of the friction coefficient on the long-time behavior of the output signal of a harmonic oscillator with fluctuating frequency subjected to an external periodic force and an additive thermal noise is considered. The colored fluctuations of the oscillator frequency are modeled as a three-level Markovian telegraph noise. The main purpose of this work is to demonstrate, based on exact expressions, that the resonance is manifested in the dependence of the response function and the complex susceptibility of the oscillator upon the friction coefficient. The advantage of the latter effect is that the control parameter is the damping coefficient, which can easily be varied in possible experiments as well as potential technological applications.

Laas, K.; Mankin, R.

2009-10-01

106

Friction-induced Resonance of a Stochastic Oscillator  

SciTech Connect

The influence of the friction coefficient on the long-time behavior of the output signal of a harmonic oscillator with fluctuating frequency subjected to an external periodic force and an additive thermal noise is considered. The colored fluctuations of the oscillator frequency are modeled as a three-level Markovian telegraph noise. The main purpose of this work is to demonstrate, based on exact expressions, that the resonance is manifested in the dependence of the response function and the complex susceptibility of the oscillator upon the friction coefficient. The advantage of the latter effect is that the control parameter is the damping coefficient, which can easily be varied in possible experiments as well as potential technological applications.

Laas, K.; Mankin, R. [Institute of Mathematics and Natural Sciences, Tallinn University 25 Narva Road, 10120 Tallinn (Estonia)

2009-10-29

107

Effects of spike-time-dependent plasticity on the stochastic resonance of small-world neuronal networks  

NASA Astrophysics Data System (ADS)

The phenomenon of stochastic resonance in Newman-Watts small-world neuronal networks is investigated when the strength of synaptic connections between neurons is adaptively adjusted by spike-time-dependent plasticity (STDP). It is shown that irrespective of the synaptic connectivity is fixed or adaptive, the phenomenon of stochastic resonance occurs. The efficiency of network stochastic resonance can be largely enhanced by STDP in the coupling process. Particularly, the resonance for adaptive coupling can reach a much larger value than that for fixed one when the noise intensity is small or intermediate. STDP with dominant depression and small temporal window ratio is more efficient for the transmission of weak external signal in small-world neuronal networks. In addition, we demonstrate that the effect of stochastic resonance can be further improved via fine-tuning of the average coupling strength of the adaptive network. Furthermore, the small-world topology can significantly affect stochastic resonance of excitable neuronal networks. It is found that there exists an optimal probability of adding links by which the noise-induced transmission of weak periodic signal peaks.

Yu, Haitao; Guo, Xinmeng; Wang, Jiang; Deng, Bin; Wei, Xile

2014-09-01

108

Motorist's vestibular disorientation syndrome.  

PubMed Central

Six patients are described who experienced difficulty in driving a motor car. Four had illusions that the car was turning, which occurred particularly on open, featureless roads or the brows of hills and caused the driver to stop. All patients had peripheral or central neurootological abnormalities, but the only finding consistent with the directionality of the symptoms was an unpleasantly increased sense of circularvection during optokinetic stimulation in the direction of the illusion. These problems occur because of a false sense of orientation arising either from inappropriate signals from disordered vestibular canal and otolith organs or from a disordered central interpretation of vestibular information, and become manifest in the absence of adequate visual stabilisation. The other two patients with lateralised vestibular disease made inappropriate steering adjustments in the direction of the imbalance of vestibular tone. PMID:3875689

Page, N G; Gresty, M A

1985-01-01

109

Three dimensional nuclear magnetic resonance spectroscopic imaging of sodium ions using stochastic excitation and oscillating gradients  

SciTech Connect

Nuclear magnetic resonance (NMR) spectroscopic imaging of {sup 23}Na holds promise as a non-invasive method of mapping Na{sup +} distributions, and for differentiating pools of Na{sup +} ions in biological tissues. However, due to NMR relaxation properties of {sup 23}Na in vivo, a large fraction of Na{sup +} is not visible with conventional NMR imaging methods. An alternate imaging method, based on stochastic excitation and oscillating gradients, has been developed which is well adapted to measuring nuclei with short T{sub 2}. Contemporary NMR imaging techniques have dead times of up to several hundred microseconds between excitation and sampling, comparable to the shortest in vivo {sup 23}Na T{sub 2} values, causing significant signal loss. An imaging strategy based on stochastic excitation has been developed which greatly reduces experiment dead time by reducing peak radiofrequency (RF) excitation power and using a novel RF circuit to speed probe recovery. Continuously oscillating gradients are used to eliminate transient eddy currents. Stochastic {sup 1}H and {sup 23}Na spectroscopic imaging experiments have been performed on a small animal system with dead times as low as 25{mu}s, permitting spectroscopic imaging with 100% visibility in vivo. As an additional benefit, the encoding time for a 32x32x32 spectroscopic image is under 30 seconds. The development and analysis of stochastic NMR imaging has been hampered by limitations of the existing phase demodulation reconstruction technique. Three dimensional imaging was impractical due to reconstruction time, and design and analysis of proposed experiments was limited by the mathematical intractability of the reconstruction method. A new reconstruction method for stochastic NMR based on Fourier interpolation has been formulated combining the advantage of a several hundredfold reduction in reconstruction time with a straightforward mathematical form.

Frederick, B.deB. [California Univ., Berkeley, CA (United States); [Lawrence Berkeley Lab., CA (United States)

1994-12-01

110

Stochastic resonance with a single metastable state: Thermal instability in NbN superconducting stripline resonators  

E-print Network

stripline resonators Eran Segev,* Baleegh Abdo, Oleg Shtempluck, and Eyal Buks Department of Electrical; published 14 January 2008 We study thermal instability in NbN superconducting stripline resonators amplification. In this Brief Report, we investigate SR and amplification in a superconducting SC NbN stripline

Buks, Eyal

111

Central cross-modal stochastic resonance in human tactile blink reflex  

NASA Astrophysics Data System (ADS)

We study cross-modal stochastic resonance in the human brain. The neural circuit in the brainstem for integration of both the auditory afferent pathway used to apply background noise and the tactile sensory pathway used to apply a signal is well known, so we expect a direct integration of signal and noise in this distinct circuit of the brain. Our results indeed confirm an optimization of response probabilities of tactile blink reflex by auditory noise, suggesting the direct involvement of background noise in the cross-modal sensory integration.

Yasuda, Hideaki; Miyaoka, Tsuyoshi; Horiguchi, Jun; Yamamoto, Yoshiharu

2007-07-01

112

Stochastic resonant response in the transient boiling regime with periodic heat release  

NASA Astrophysics Data System (ADS)

Results of experimental investigation into thermal pulsations with a transition from the bubble to the film boiling regime of water in a wire heater with periodic Joule release are presented. The intermittency of the bubble and film regimes was observed with the frequencies of the periodic current component lower than 0.1 Hz. The amplitude of thermal pulsations increased by a factor of approximately 4 in this case. These results are interpreted as the stochastic resonant response of the system when the periodic component of pulsations increases in the presence of noise.

Vinogradov, A. V.; Skokov, V. N.; Koverda, V. P.

2014-10-01

113

Detecting signals buried in noise via nanowire transistors using stochastic resonance  

NASA Astrophysics Data System (ADS)

We demonstrate stochastic resonance (SR), which takes advantage of noise to detect a weak signal, using a field-effect transistor (FET). An FET's structure composed of a nanowire channel enables current characteristics to show strong nonlinearity, which overcomes thermal limitation, and dynamic bistability, both of which boost an effect of SR and silhouette noise from noise. Moreover, the dynamic bistability enables SR effect to be enhanced by adding common noise to multiple FETs. The FET providing such unique characteristics opens the way to use SR for practical applications.

Nishiguchi, Katsuhiko; Fujiwara, Akira

2012-11-01

114

Note: On-line weak signal detection via adaptive stochastic resonance  

NASA Astrophysics Data System (ADS)

We design an instrument with a novel embedded adaptive stochastic resonance (SR) algorithm that consists of a SR module and a digital zero crossing detection module for on-line weak signal detection in digital signal processing applications. The two modules are responsible for noise filtering and adaptive parameter configuration, respectively. The on-line weak signal detection can be stably achieved in seconds. The prototype instrument exhibits an advance of 20 dB averaged signal-to-noise ratio and 5 times averaged adjust R-square as compared to the input noisy signal, in considering different driving frequencies and noise levels.

Lu, Siliang; He, Qingbo; Kong, Fanrang

2014-06-01

115

Note: On-line weak signal detection via adaptive stochastic resonance.  

PubMed

We design an instrument with a novel embedded adaptive stochastic resonance (SR) algorithm that consists of a SR module and a digital zero crossing detection module for on-line weak signal detection in digital signal processing applications. The two modules are responsible for noise filtering and adaptive parameter configuration, respectively. The on-line weak signal detection can be stably achieved in seconds. The prototype instrument exhibits an advance of 20 dB averaged signal-to-noise ratio and 5 times averaged adjust R-square as compared to the input noisy signal, in considering different driving frequencies and noise levels. PMID:24985875

Lu, Siliang; He, Qingbo; Kong, Fanrang

2014-06-01

116

The resonance overlap criterion and the onset of stochastic behavior in the restricted three-body problem  

NASA Technical Reports Server (NTRS)

The resonance overlap criterion for the onset of stochastic behavior is applied to the planar circular-restricted three-body problem with small mass ratio (mu). Its predictions for mu = 0.001, 0.0001, and 0.00001 are compared to the transitions observed in the numerically determined Kolmogorov-Sinai entropy and found to be in remarkably good agreement. In addition, an approximate scaling law for the onset of stochastic behavior is derived.

Wisdom, J.

1980-01-01

117

Stochastic resonance whole-body vibration improves postural control in health care professionals: a worksite randomized controlled trial.  

PubMed

Slip, trip, and fall injuries are frequent among health care workers. Stochastic resonance whole-body vibration training was tested to improve postural control. Participants included 124 employees of a Swiss university hospital. The randomized controlled trial included an experimental group given 8 weeks of training and a control group with no intervention. In both groups, postural control was assessed as mediolateral sway on a force plate before and after the 8-week trial. Mediolateral sway was significantly decreased by stochastic resonance whole-body vibration training in the experimental group but not in the control group that received no training (p < .05). Stochastic resonance whole-body vibration training is an option in the primary prevention of balance-related injury at work. PMID:24806038

Elfering, Achim; Schade, Volker; Stoecklin, Lukas; Baur, Simone; Burger, Christian; Radlinger, Lorenz

2014-05-01

118

Supernarrow Spectral Peaks and High Frequency Stochastic Resonance in Systems with Coexisting Periodic Attractors  

E-print Network

The kinetics of a periodically driven nonlinear oscillator, bistable in a nearly resonant field, has been investigated theoretically and through analogue experiments. An activation dependence of the probabilities of fluctuational transitions between the coexisting attractors has been observed, and the activation energies of the transitions have been calculated and measured for a wide range of parameters. The position of the kinetic phase transition (KPT), at which the populations of the attractors are equal, has been established. A range of critical phenomena is shown to arise in the vicinity of the KPT including, in particular, the appearance of a supernarrow peak in the spectral density of the fluctuations, and the occurrence of high-frequency stochastic resonance (HFSR). The experimental measurements of the transition probabilities, the KPT line, the multipeaked spectral densities, the strength of the supernarrow spectral peak, and of the HFSR effect are shown to be in good agreement with the theoretical predictions.

MI Dykman; DG Luchinsky; R Mannella; PVE McClintock; ND Stein; NG Stocks

1993-08-09

119

The stochastic dynamics of a nanobeam near an optomechanical resonator in a viscous fluid  

NASA Astrophysics Data System (ADS)

We quantify the Brownian driven, stochastic dynamics of an elastic nanobeam immersed in a viscous fluid that is partially wrapped around a microdisk optical resonator. This configuration has been proposed as an optomechanical and nanoscale analog of the atomic force microscope [Srinivasan et al., Nano Lett. 11, 791 (2011)]. A small gap between the nanobeam and microdisk is necessary for the optomechanical transduction of the mechanical motion of the nanobeam. We compute the stochastic dynamics of the nanobeam in fluid for the precise conditions of the laboratory using deterministic finite element simulations and the fluctuation dissipation theorem. We investigate the dynamics of a nanobeam in water and in air and quantify the significance of the fluid-solid interaction between the nanobeam and the optical resonator. Our results in air show that, despite the complex geometry of the nanobeam, it can still be represented approximately as a damped simple harmonic oscillator. On the other hand, when the nanobeam is immersed in water there are significant deviations from the dynamics of a simple harmonic oscillator. The small gap between the nanobeam and the microdisk is found to be a significant source of additional dissipation. In air, the quality factor of the mechanical oscillation of the nanobeam is reduced by an order of magnitude due to the presence of the microdisk, however, the dynamics remain underdamped even in the presence of the microdisk. On the other hand, when placed in water, the dynamics without the microdisk is underdamped and with the microdisk the dynamics become strongly over damped.

Epstein, S.; Paul, M. R.

2013-10-01

120

Weak-Periodic Stochastic Resonance in a Parallel Array of Static Nonlinearities  

PubMed Central

This paper studies the output-input signal-to-noise ratio (SNR) gain of an uncoupled parallel array of static, yet arbitrary, nonlinear elements for transmitting a weak periodic signal in additive white noise. In the small-signal limit, an explicit expression for the SNR gain is derived. It serves to prove that the SNR gain is always a monotonically increasing function of the array size for any given nonlinearity and noisy environment. It also determines the SNR gain maximized by the locally optimal nonlinearity as the upper bound of the SNR gain achieved by an array of static nonlinear elements. With locally optimal nonlinearity, it is demonstrated that stochastic resonance cannot occur, i.e. adding internal noise into the array never improves the SNR gain. However, in an array of suboptimal but easily implemented threshold nonlinearities, we show the feasibility of situations where stochastic resonance occurs, and also the possibility of the SNR gain exceeding unity for a wide range of input noise distributions. PMID:23505523

Ma, Yumei; Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

2013-01-01

121

Model for biological communication in a nanofabricated cell-mimic driven by stochastic resonance  

PubMed Central

Cells offer natural examples of highly efficient networks of nanomachines. Accordingly, both intracellular and intercellular communication mechanisms in nature are looked to as a source of inspiration and instruction for engineered nanocommunication. Harnessing biological functionality in this manner requires an interdisciplinary approach that integrates systems biology, synthetic biology, and nanofabrication. Here, we present a model system that exemplifies the synergism between these realms of research. We propose a synthetic gene network for operation in a nanofabricated cell mimic array that propagates a biomolecular signal over long distances using the phenomenon of stochastic resonance. Our system consists of a bacterial quorum sensing signal molecule, a bistable genetic switch triggered by this signal, and an array of nanofabricated cell mimic wells that contain the genetic system. An optimal level of noise in the system helps to propagate a time-varying AHL signal over long distances through the array of mimics. This noise level is determined both by the system volume and by the parameters of the genetic network. Our proposed genetically driven stochastic resonance system serves as a testbed for exploring the potential harnessing of gene expression noise to aid in the transmission of a time-varying molecular signal. PMID:21731597

Karig, David K.; Siuti, Piro; Dar, Roy D.; Retterer, Scott. T.; Doktycz, Mitchel J.; Simpson, Michael L.

2011-01-01

122

Do Basal Ganglia Amplify Willed Action by Stochastic Resonance? A Model  

PubMed Central

Basal ganglia are usually attributed a role in facilitating willed action, which is found to be impaired in Parkinson's disease, a pathology of basal ganglia. We hypothesize that basal ganglia possess the machinery to amplify will signals, presumably weak, by stochastic resonance. Recently we proposed a computational model of Parkinsonian reaching, in which the contributions from basal ganglia aid the motor cortex in learning to reach. The model was cast in reinforcement learning framework. We now show that the above basal ganglia computational model has all the ingredients of stochastic resonance process. In the proposed computational model, we consider the problem of moving an arm from a rest position to a target position: the two positions correspond to two extrema of the value function. A single kick (a half-wave of sinusoid, of sufficiently low amplitude) given to the system in resting position, succeeds in taking the system to the target position, with high probability, only at a critical noise level. But for suboptimal noise levels, the model arm's movements resemble Parkinsonian movement symptoms like akinetic rigidity (low noise) and dyskinesias (high noise). PMID:24302984

Chakravarthy, V. Srinivasa

2013-01-01

123

M-ary suprathreshold stochastic resonance: Generalization and scaling beyond binary threshold nonlinearities  

NASA Astrophysics Data System (ADS)

Suprathreshold stochastic resonance is a form of noise-enhanced processing that is observed only when more than one noisy nonlinear signal processing element is combined in a parallel array, such as in biological and engineered sensory transduction. The case of binary threshold nonlinearities combined into arrays of independently noisy components has previously been studied extensively, and quantified in terms of how information transmission through the array varies with the input noise level, and the number of elements, N. Here we generalise this setup to arrays of N identical M-ary threshold nonlinearities. We show that enhanced suprathreshold stochastic resonance occurs for M? 1 and N > 1, implying that M identical quantizing sensors can be combined to provide higher resolution than a single sensor, provided they are independently noisy. We also study the system's scaling with M and N and conclude that although binary quantizing nonlinearities are superior to M-ary nonlinearities in the presence of large noise, the opposite holds in the presence of small noise. This suggests that multiple identical but coarse-resolution sensors can be useful for acquiring low SNR signals while few high-resolution identical sensors are superior for high SNR signals.

McDonnell, Mark D.; Gao, Xiao

2014-12-01

124

Intracanalicular Meningioma Mimicking Vestibular Schwannoma  

Microsoft Academic Search

Summary: Three cases of intracanalicular meningioma mimicking vestibular schwannoma are presented. In each case, a contrast-enhancing mass filling the internal audi- tory canal was identified on MR images and was originally diagnosed as a vestibular schwannoma. Although it is dif- ficult to differentiate definitively between these lesions pre- operatively, imaging findings inconsistent with a diagnosis of vestibular schwannoma can be

Katsuyuki Asaoka; David M. Barrs; John H. Sampson; John T. McElveen Jr.; Debara L. Tucci; Takanori Fukushima

125

Vestibular schwannoma: negative growth and audiovestibular features  

Microsoft Academic Search

At the University Medical Center Utrecht, non-operative management was used for 44 patients with a unilateral vestibular\\u000a schwannoma between 1990 and 1997. During that period, consecutive tumor sizes were determined by magnetic resonance imaging.\\u000a Three of the 44 patients showed an average decrease in tumor size of 16.7% according to American Academy of Otolaryngology-Head\\u000a and Neck Surgery standards. This study

Ernestine M. Stipkovits; Kees Graamans; Johannes E. Van Dijk

2001-01-01

126

Recovery from vestibular ototoxicity  

NASA Technical Reports Server (NTRS)

OBJECTIVE: Determine whether subjects with documented vestibular ototoxicity recover vestibular function and, if so, investigate the recovery dynamics. STUDY DESIGN: Prospective and retrospective reviews and repeated measures. SETTING: Clinical research and technology center. SUBJECTS: Twenty-eight subjects who received vestibulotoxic medications were followed for at least 12 months after initial treatment. CONTROLS: Our subject sample was compared with a published database of normal individuals. INTERVENTIONS: All 28 subjects received systemically administered medications known to be ototoxic. The subjects' treating physicians controlled medication, dosage, and administration schedules. MAIN OUTCOME MEASURES: Tests of horizontal canal vestibulo-ocular function were performed. Subjects' auditory and vestibular symptoms were recorded. RESULTS: Eleven subjects (39%) showed changes in horizontal canal vestibulo-ocular gain constant (GC) and/or time constant (TC) consistent with vestibular ototoxicity. When tested 1 year after ototoxic drug administration, eight of the nine subjects who experienced ototoxic decrease in GC showed a recovery of GC to normal limits. Only one of the eight subjects who experienced ototoxic decrease in TC showed recovery of TC to within normal limits. Ototoxicity onset and recovery were independent of baseline vestibular function, and ototoxicity onset did not correlate with cumulative dose of ototoxic medication. There was no relationship between subjective symptoms and ototoxicity onset. CONCLUSIONS: Recovery of GC after vestibular ototoxicity is more commonly observed than recovery of TC. Because ototoxic changes developed and continued in an unpredictable time and manner in relation to ototoxic drug administration, we propose that once ototoxic changes in vestibulo-ocular reflex are detected, ototoxic medications should be discontinued as soon as possible.

Black, F. O.; Gianna-Poulin, C.; Pesznecker, S. C.

2001-01-01

127

Vestibular-Ocular Reflex  

NSDL National Science Digital Library

In this activity, learners will perform various investigations to understand the vestibular-ocular reflex and learn about the importance of visual cues in maintaining balance. During the two-part activity, learners will compare the stability of a moving image under two conditions as well as compare the effects of rotation on the sensation of spinning under varying conditions. This lesson guide includes background information, review and critical thinking questions with answers, and handouts. Educators can also use this activity to discuss how the brain functions in space and how researchers study the vestibular function in space.

Marlene Y. Macleish, Ed D.; Bernice R. Mclean, M. E.

2013-01-30

128

Modern vestibular function testing.  

PubMed Central

Current tests of vestibular function concentrate on the horizontal semicircular canal-ocular reflex because it is the easiest reflex to stimulate (calorically and rotationally) and record (using electro-oculography). Tests of the other vestibulo-ocular reflexes (vertical semicircular canal and otolith) and of the vestibulospinal reflexes have yet to be shown useful in the clinical setting. Digital video recording of eye movements and vestibular-evoked responses are promising new technologies that may affect clinical testing in the near future. PMID:2660408

Baloh, R W; Furman, J M

1989-01-01

129

Drift resonance effect on stochastic runaway electron orbit in the presence of low-order magnetic perturbations  

NASA Astrophysics Data System (ADS)

During major disruptions, an induced loop voltage accelerates runaway electrons (REs) towards high energy, being in the order of 1–100 MeV in present tokamaks and ITER. The stochastization mechanisms of such high-energy RE drift orbits are investigated by three-dimensional (3D) orbit following in tokamak plasmas. Drift resonance is shown to play an important role in determining the onset of stochastic drift orbits for different electron energies, particularly in cases with low-order perturbations that have radially global eigenfunctions of the scale of the plasma minor radius. The drift resonance due to the coupling between the cross-field drift motion with radially global modes yields a secondary island structure in the RE drift orbit, where the width of the secondary drift islands shows a square-root dependence on the relativistic gamma factor ?. Only for highly relativistic REs (? ? 1), the widths of secondary drift islands are comparable with those of magnetic islands due to the primary resonance, thus the stochastic threshold becoming sensitive to the RE energy. Because of poloidal asymmetry due to toroidicity, the threshold becomes sensitive not only to the relative amplitude but also to the phase difference between the modes. In this paper, some examples of 3D orbit-following calculations are presented for analytic models of magnetic perturbations with multiple toroidal mode numbers, for both possibilities that the drift resonance enhances and suppresses the stochastization being illustrated.

Matsuyama, A.; Yagi, M.; Kagei, Y.; Nakajima, N.

2014-12-01

130

Stochastic resonance in the thermohaline circulation P. V'elez , A. Alvarez 1 , P. Colet, J. Tintor'e  

E-print Network

1 Stochastic resonance in the thermohaline circulation P. V'elez , A. Alvarez 1 , P. Colet, J might be related to transitions between stable equilibrium states of the ocean thermohaline circulation of the thermohaline circulation seems well established, the mechanism and magnitude of the forcings that could

Colet, Pere

131

Mechanism of stochastic resonance enhancement in neuronal models driven by 1/f noise Daichi Nozaki,1,2  

E-print Network

Mechanism of stochastic resonance enhancement in neuronal models driven by 1/f noise Daichi Nozaki s : 87.80.Tq, 05.40.Ca I. INTRODUCTION It has recently been recognized that noise can enhance it has been shown in several experimental studies that noise can assist neural systems in detecting sub

Collins, James J.

132

Management of vestibular migraine  

PubMed Central

Vestibular migraine is considered to be the second most common cause of vertigo and the most common cause of spontaneous episodic vertigo. The duration of attacks varies from seconds to days, usually lasting minutes to hours, and they mostly occur independently of headaches. Long-lasting individual attacks are treated with generic antivertiginous and antiemetic drugs. Specific antimigraine drugs are unlikely to be very effective for rescue. The mainstay of the management of vestibular migraine is prophylactic medication. To date, there are no controlled trials available; the body of knowledge builds on case series and retrospective or observational studies. Most drugs are also used for the prevention of migraine headaches. The choice of medication should be guided by its side effect profile and the comorbidities of patients. Betablockers such as propanolol or metoprolol are preferred in patients with hypertension but in the absence of asthma. Anticonvulsants include topiramate when patients are obese, valproic acid and lamotrigine. Lamotrigine is preferred if vertigo is more frequent than headaches. Calcium antagonists include verapamil and flunarizine. If patients have anxiety, tricyclic antidepressants such as amitryptiline or nortryptiline or SSRIs and benzodiazepines such as clonazepam are recommended. Acetazolamide is effective in rare genetic disorders related to migraine-like episodic ataxia; however, its place in vestibular migraine is still to be established. Nonpharmacological measures such as diet, sleep, hygiene and avoidance of triggers are recommended as they are for migraine. Vestibular rehabilitation might be useful when there are complications such as loss of confidence in balance or visual dependence. PMID:21694818

Bisdorff, Alexandre R.

2011-01-01

133

Growth of stochastic resonance in neuronal ensembles with the input signal intensity.  

PubMed

The presence of noise can improve the response of certain nonlinear systems to input signals through the effects of stochastic resonance (SR). The optimal noise intensity for SR is proportional to the signal frequency if the signal is periodic, but proportional to the signal intensity if the signal is aperiodic. Here, we demonstrate using linear response theory that the optimal noise intensity for SR is necessarily dependent on the signal intensity even if the signal is periodic. We also demonstrate that the SR curves grow according to the signal intensity from a bell-shaped curve to a plateau, resulting in the emergence of SR without tuning. In particular, we present a theoretical analysis indicating that the SR peak shifts with the signal intensity due to the scaling of the stationary neuronal firings. The growth of SR may serve as a useful design principle for many noise-exploiting applications. PMID:23005467

Yonekura, Shogo; Kuniyoshi, Yasuo; Kawaguchi, Yoichiro

2012-07-01

134

The Recovery of Weak Impulsive Signals Based on Stochastic Resonance and Moving Least Squares Fitting  

PubMed Central

In this paper a stochastic resonance (SR)-based method for recovering weak impulsive signals is developed for quantitative diagnosis of faults in rotating machinery. It was shown in theory that weak impulsive signals follow the mechanism of SR, but the SR produces a nonlinear distortion of the shape of the impulsive signal. To eliminate the distortion a moving least squares fitting method is introduced to reconstruct the signal from the output of the SR process. This proposed method is verified by comparing its detection results with that of a morphological filter based on both simulated and experimental signals. The experimental results show that the background noise is suppressed effectively and the key features of impulsive signals are reconstructed with a good degree of accuracy, which leads to an accurate diagnosis of faults in roller bearings in a run-to failure test. PMID:25076220

Jiang, Kuosheng.; Xu, Guanghua.; Liang, Lin.; Tao, Tangfei.; Gu, Fengshou.

2014-01-01

135

Improved Detection of Magnetic Signals by a MEMS Sensor Using Stochastic Resonance  

PubMed Central

We introduce the behavior of the electrical output response of a magnetic field sensor based on microelectromechanical systems (MEMS) technology under different levels of controlled magnetic noise. We explored whether a particular level of magnetic noise applied on the vicinity of the MEMS sensor can improve the detection of subthreshold magnetic fields. We examined the increase in the signal-to-noise ratio (SNR) of such detected magnetic fields as a function of the magnetic noise intensity. The data disclosed an inverted U-like graph between the SNR and the applied magnetic noise. This finding shows that the application of an intermediate level of noise in the environment of a MEMS magnetic field sensor improves its detection capability of subthreshold signals via the stochastic resonance phenomenon. PMID:25329563

Herrera-May, Agustín L.; Tapia, Jesus A.; Domínguez-Nicolás, Saúl M.; Juarez-Aguirre, Raul; Gutierrez-D, Edmundo A.; Flores, Amira; Figueras, Eduard; Manjarrez, Elias

2014-01-01

136

Stochastic resonance in a linear system with random damping parameter driven by trichotomous noise  

NASA Astrophysics Data System (ADS)

The stochastic resonance (SR) in a second-order linear system driven by a trichotomous noise and an external periodic signal is investigated. By the use of the properties of the trichotomous noise and the Shapiro-Loginov formula, the exact expression for the output spectral amplification (SPA) of the system is obtained. The non-monotonic influence of the coefficient of the trichotomous noise on the SPA is found. It is shown that the SPA is a non-monotonic function of the amplitude, the correlation rate and the probability of the trichotomous noise. The SPA varies non-monotonically with the frequency of the driving signal, the damping coefficient and the frequency of the linear system.

Guo, Feng; Li, Heng; Liu, Jing

2014-09-01

137

The recovery of weak impulsive signals based on stochastic resonance and moving least squares fitting.  

PubMed

In this paper a stochastic resonance (SR)-based method for recovering weak impulsive signals is developed for quantitative diagnosis of faults in rotating machinery. It was shown in theory that weak impulsive signals follow the mechanism of SR, but the SR produces a nonlinear distortion of the shape of the impulsive signal. To eliminate the distortion a moving least squares fitting method is introduced to reconstruct the signal from the output of the SR process. This proposed method is verified by comparing its detection results with that of a morphological filter based on both simulated and experimental signals. The experimental results show that the background noise is suppressed effectively and the key features of impulsive signals are reconstructed with a good degree of accuracy, which leads to an accurate diagnosis of faults in roller bearings in a run-to failure test. PMID:25076220

Jiang, Kuosheng; Xu, Guanghua; Liang, Lin; Tao, Tangfei; Gu, Fengshou

2014-01-01

138

Generalized stochastic resonance in a linear fractional system with a random delay  

NASA Astrophysics Data System (ADS)

The generalized stochastic resonance (GSR) phenomena in a linear fractional random-delayed system driven by a weak periodic signal and an additive noise are considered in this paper. A random delay is considered for a linear fractional Langevin equation to describe the intercellular signal transmission and material exchange processes in ion channels. By virtue of the small delay approximation and Laplace transformation, the analytical expression for the amplitude of the first-order steady state moment is obtained. The simulation results show that the amplitude curves as functions of different system parameters behave non-monotonically and exhibit typical characteristics of GSR phenomena. Furthermore, a physical explanation for all the GSR phenomena is given and the cooperative effects of random delay and the fractional memory are also discussed.

Gao, Shi-Long

2012-12-01

139

Simulating electron spin resonance spectra of nitroxide spin labels from molecular dynamics and stochastic trajectories  

PubMed Central

Simulating electron spin resonance spectra of nitroxide spin labels from motional models is necessary for the quantitative analysis of experimental spectra. We present a framework for modeling the spin label dynamics by using trajectories such as those from molecular dynamics (MD) simulations combined with stochastic treatment of the global protein tumbling. This is achieved in the time domain after two efficient numerical integrators are developed: One for the quantal dynamics of the spins and the other for the classical rotational diffusion. For the quantal dynamics, we propagate the relevant part of the spin density matrix in Hilbert space. For the diffusional tumbling, we work with quaternions, which enables the treatment of anisotropic diffusion in a potential expanded as a sum of spherical harmonics. Time-averaging arguments are invoked to bridge the gap between the smaller time step of the MD trajectories and the larger time steps appropriate for the rotational diffusion and?or quantal spin dynamics. PMID:18447510

Sezer, Deniz; Freed, Jack H.; Roux, Benoît

2008-01-01

140

Model for biological communication in a nanofabricated cell-mimic driven by stochastic resonance  

SciTech Connect

Cells offer natural examples of highly efficient networks of nanomachines. Accordingly, both intracellular and intercellular communication mechanisms in nature are looked to as a source of inspiration and instruction for engineered nanocommunication. Harnessing biological functionality in this manner requires an interdisciplinary approach that integrates systems biology, synthetic biology, and nanofabrication. Recent years have seen the amassing of a tremendous wealth of data from the sequencing of new organisms and from high throughput expression experiments. At the same time, a deeper fundamental understanding of individual cell function has been developed, as exemplified by the growth of fields such as noise biology, which seeks to characterize the role of noise in gene expression. The availability of well characterized biological components coupled with a deeper understanding of cell function has led to efforts to engineer both living cells and to create bio-like functionality in non-living substrates in the field of synthetic biology. Here, we present a model system that exemplifies the synergism between these realms of research. We propose a synthetic gene network for operation in a nanofabricated cell mimic array that propagates a biomolecular signal over long distances using the phenomenon of stochastic resonance. Our system consists of a bacterial quorum sensing signal molecule, a bistable genetic switch triggered by this signal, and an array of nanofabricated cell mimic wells that contain the genetic system. An optimal level of noise in the system helps to propagate a time-varying AHL signal over long distances through the array of mimics. This noise level is determined both by the system volume and by the parameters of the genetic network. Our proposed genetically driven stochastic resonance system serves as a testbed for exploring the potential harnessing of gene expression noise to aid in the transmission of a time-varying molecular signal.

Karig, David K [ORNL; Siuti, Piro [ORNL; Dar, Roy D. [University of Tennessee, Knoxville (UTK); Retterer, Scott T [ORNL; Doktycz, Mitchel John [ORNL; Simpson, Michael L [ORNL

2011-01-01

141

Postural Compensation for Vestibular Loss  

PubMed Central

To what extent can remaining sensory information and/or sensory biofeedback compensate for loss of vestibular information in controlling postural equilibrium? The primary role of the vestibulospinal system is as a vertical reference for control of the trunk in space, with increasing importance as the surface becomes increasingly unstable. Our studies with patients with bilateral loss of vestibular function show that vision or light touch from a fingertip can substitute as a reference for earth vertical to decrease variability of trunk sway when standing on an unstable surface. However, some patients with bilateral loss compensate better than others and we find that those with more complete loss of bilateral vestibular function compensate better than those with measurable vestibulo-ocular reflexes. In contrast, patients with unilateral vestibular loss who reweight sensory dependence to rely on their remaining unilateral vestibular function show better functional performance than those who do not increase vestibular weighting on an unstable surface. Light touch of <100 grams or auditory biofeedback can be added as a vestibular vertical reference to stabilize trunk sway during stance. Postural ataxia during tandem gait in patients with unilateral vestibular loss is also significantly improved with vibrotactile biofeedback to the trunk, beyond improvements due to practice. Vestibular rehabilitation should focus on decreasing hypermetria, decreasing an over-dependence on surface somatosensory inputs, increasing use of any remaining vestibular function, substituting or adding alternative sensory feedback related to trunk sway, and practicing challenging balance tasks on unstable surfaces. PMID:20086283

Horak, Fay B.

2010-01-01

142

Can Electrical Vestibular Noise Be Used for the Treatment of Brain Diseases?  

NASA Astrophysics Data System (ADS)

The therapy currently available for the treatment of degenerative neurological diseases is far from satisfactory, and a novel therapeutic strategy, especially for pharmacologically unresponsive patients, would be welcomed. The vestibular nerves are known to influence neuronal circuits in the medullary cardiovascular areas and, through the cerebellar vermis, the basal ganglia and the limbic system. By means of noisy galvanic vestibular stimulation (GVS), it may now be possible to ameliorate blunted responsiveness of degenerated neuronal circuits in the brains of multiple system atrophy (MSA) and/or Parkinson's disease (PD) patients, through a mechanism known as stochastic resonance. We evaluate the effect of 24-hour noisy GVS on long-term heart rate dynamics in seven MSA patients, and on daytime locomotor activity dynamics in twelve patients with either PD or levodopa unresponsive parkinsonism. Short-range heart rate variability and long-range anti-correlation of trunk activity are significantly increased by the noisy GVS compared with sham stimulation, suggestive of improved autonomic and motor responsiveness. The noisy GVS is effective in boosting the neuro-degenerative brains of MSA and/or PD patients, including those unresponsive to standard levodopa therapy.

Yamamoto, Yoshiharu; Soma, Rika; Struzik, Zbigniew R.; Kwak, Shin

2005-11-01

143

Is Vestibular Neuritis an Immune Related Vestibular Neuropathy Inducing Vertigo?  

PubMed Central

Objectives. To review the current knowledge of the aetiology of vestibular neuritis including viral infections, vascular occlusion, and immunomediated mechanisms and to discuss the pathogenesis with relevance to pharmacotherapy. Systematic Review Methodology. Relevant publications on the aetiology and treatment of vestibular neuritis from 1909 to 2013 were analysed. Results and Conclusions. Vestibular neuritis is the second most common cause of peripheral vestibular vertigo and is due to a sudden unilateral loss of vestibular function. Vestibular neuronitis is a disorder thought to represent the vestibular-nerve equivalent of sudden sensorineural hearing loss. Histopathological studies of patients who died from unrelated clinical problems have demonstrated degeneration of the superior vestibular nerve. The characteristic signs and symptoms include sudden and prolonged vertigo, the absence of auditory symptoms, and the absence of other neurological symptoms. The aetiology and pathogenesis of the condition remain unknown. Proposed theories of causation include viral infections, vascular occlusion, and immunomediated mechanisms. The management of vestibular neuritis involves symptomatic treatment with antivertiginous drugs, causal treatment with corticosteroids, and physical therapy. Antiviral agents did not improve the outcomes. PMID:24741601

Greco, A.; Macri, G. F.; Gallo, A.; Fusconi, M.; De Virgilio, A.; Pagliuca, G.; Marinelli, C.; de Vincentiis, M.

2014-01-01

144

Double-maximum enhancement of signal-to-noise ratio gain via stochastic resonance and vibrational resonance.  

PubMed

This paper studies the signal-to-noise ratio (SNR) gain of a parallel array of nonlinear elements that transmits a common input composed of a periodic signal and external noise. Aiming to further enhance the SNR gain, each element is injected with internal noise components or high-frequency sinusoidal vibrations. We report that the SNR gain exhibits two maxima at different values of the internal noise level or of the sinusoidal vibration amplitude. For the addition of internal noise to an array of threshold-based elements, the condition for occurrence of stochastic resonance is analytically investigated in the limit of weak signals. Interestingly, when the internal noise components are replaced by high-frequency sinusoidal vibrations, the SNR gain displays the vibrational multiresonance phenomenon. In both considered cases, there are certain regions of the internal noise intensity or the sinusoidal vibration amplitude wherein the achieved maximal SNR gain can be considerably beyond unity for a weak signal buried in non-Gaussian external noise. Due to the easy implementation of sinusoidal vibration modulation, this approach is potentially useful for improving the output SNR in an array of nonlinear devices. PMID:25215715

Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

2014-08-01

145

Double-maximum enhancement of signal-to-noise ratio gain via stochastic resonance and vibrational resonance  

NASA Astrophysics Data System (ADS)

This paper studies the signal-to-noise ratio (SNR) gain of a parallel array of nonlinear elements that transmits a common input composed of a periodic signal and external noise. Aiming to further enhance the SNR gain, each element is injected with internal noise components or high-frequency sinusoidal vibrations. We report that the SNR gain exhibits two maxima at different values of the internal noise level or of the sinusoidal vibration amplitude. For the addition of internal noise to an array of threshold-based elements, the condition for occurrence of stochastic resonance is analytically investigated in the limit of weak signals. Interestingly, when the internal noise components are replaced by high-frequency sinusoidal vibrations, the SNR gain displays the vibrational multiresonance phenomenon. In both considered cases, there are certain regions of the internal noise intensity or the sinusoidal vibration amplitude wherein the achieved maximal SNR gain can be considerably beyond unity for a weak signal buried in non-Gaussian external noise. Due to the easy implementation of sinusoidal vibration modulation, this approach is potentially useful for improving the output SNR in an array of nonlinear devices.

Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

2014-08-01

146

Vestibular Schwannoma (Acoustic Neuroma) and Neurofibromatosis  

MedlinePLUS

Home Health Info Hearing, Ear Infections, and Deafness Vestibular Schwannoma (Acoustic Neuroma) and Neurofibromatosis Vestibular Schwannoma (Acoustic Neuroma) and Neurofibromatosis On this page: What ...

147

Interaction of brain areas of visual and vestibular simultaneous activity with fMRI.  

PubMed

Static body equilibrium is an essential requisite for human daily life. It is known that visual and vestibular systems must work together to support equilibrium. However, the relationship between these two systems is not fully understood. In this work, we present the results of a study which identify the interaction of brain areas that are involved with concurrent visual and vestibular inputs. The visual and the vestibular systems were individually and simultaneously stimulated, using flickering checkerboard (without movement stimulus) and galvanic current, during experiments of functional magnetic resonance imaging. Twenty-four right-handed and non-symptomatic subjects participated in this study. Single visual stimulation shows positive blood-oxygen-level-dependent (BOLD) responses (PBR) in the primary and associative visual cortices. Single vestibular stimulation shows PBR in the parieto-insular vestibular cortex, inferior parietal lobe, superior temporal gyrus, precentral gyrus and lobules V and VI of the cerebellar hemisphere. Simultaneous stimulation shows PBR in the middle and inferior frontal gyri and in the precentral gyrus. Vestibular- and somatosensory-related areas show negative BOLD responses (NBR) during simultaneous stimulation. NBR areas were also observed in the calcarine gyrus, lingual gyrus, cuneus and precuneus during simultaneous and single visual stimulations. For static visual and galvanic vestibular simultaneous stimulation, the reciprocal inhibitory visual-vestibular interaction pattern is observed in our results. The experimental results revealed interactions in frontal areas during concurrent visual-vestibular stimuli, which are affected by intermodal association areas in occipital, parietal, and temporal lobes. PMID:25300959

Della-Justina, Hellen M; Gamba, Humberto R; Lukasova, Katerina; Nucci-da-Silva, Mariana P; Winkler, Anderson M; Amaro, Edson

2015-01-01

148

Tinnitus of vestibular origin.  

PubMed

During the exercises devised by Seymont and/or Epley for rehabilitation of benign paroxysmal positional vertigo, we observed that the accompanying tinnitus disappeared immediately in some patients. Following this observation and using the same maneuver, we examined two groups of patients. The first group included 86 patients with continuous tinnitus, or tinnitus in specific head/body positions. whose origination was associated with recent vestibular symptomatology. The second group included 100 patients with positional tinnitus, but without any vestibular disorder. Ages ranged between 35 and 78 years and gender distribution was 114 females and 72 males. It was shown that 29 patients in the first group (33.2%) and 18 patients in the second group (18%) could be released from their tinnitus. Eleven patients in the first group (12.7%) and 7 patients in the second group (7%) noticed a reduction of their tinnitus. These results show that in the above-mentioned cases relief of vestibular symptoms alleviates the tinnitus. This could be mediated by a reduction in autonomic activity, known to affect tinnitus. PMID:11318463

Gavalas, G J; Passou, E M; Vathilakis, J M

2001-01-01

149

Improving Early Adaptation Following Long Duration Spaceflight by Enhancing Vestibular Information  

NASA Technical Reports Server (NTRS)

Crewmember adapted to the microgravity state may need to egress the vehicle within a few minutes for safety and operational reasons after g-transitions. The transition from one sensorimotor state to another consists of two main mechanisms: strategic and plastic-adaptive and have been demonstrated in astronauts returning after long duration space flight. Strategic modifications represent "early adaptation" -immediate and transitory changes in control that are employed to deal with short-term changes in the environment. If these modifications are prolonged then plastic-adaptive changes are evoked that modify central nervous system function, automating new behavioral responses. More importantly, this longer term adaptive recovery mechanism was significantly associated with their strategic ability to recover on the first day after return to Earth G. We are developing a method based on stochastic resonance (SR) to enhance information transfer by improving the brain's ability to detect vestibular signals especially when combined with balance training exercises for rapid improvement in functional skill, for standing and mobility. The countermeasure to improve post-flight balance and locomotor disturbances is a stimulus delivery system that is wearable/portable providing low imperceptible levels of white noise based binaural bipolar electrical stimulation of the vestibular system (stochastic vestibular stimulation, SVS). The techniques for improving signal detection using SVS may thus provide additional information to improve such strategic abilities and thus help in significantly reducing the number of days required to recover functional performance to preflight levels after long duration space flight. We have conducted a series of studies to document the efficacy of SVS stimulation on balance/locomotion tasks on unstable surfaces and motion tracking tasks during intra-vestibular system conflicts. In an initial study, we showed that SVS improved overall balance performance while standing on an unstable surface indicating that SVS may be sufficient to provide a comprehensive countermeasure approach for improving postural stability. In a second study, we showed that SVS improved locomotor performance on a treadmill mounted on an oscillating platform indicating that SVS may also be used to maximize locomotor performance during walking in unstable environments. In a third study, SVS was evaluated during an otolith-canal conflict scenario in a variable radius centrifuge at low frequency of oscillation (0.1 Hz) on both eye movements and perceptual responses (using a joystick) to track imposed oscillations. The variable radius centrifuge provides a selective tilting sensation that is detectable only by the otolith organs providing conflicting information from the canal organs of the vestibular system (intra-vestibular conflict). Results show that SVS significantly reduced the timing difference between both the eye movement responses as well as the perceptual tracking responses with respect to the imposed tilt sensations. These results indicate that SVS can improve performance in sensory conflict scenarios like that experienced during space flight. Such a SR countermeasure will act synergistically along with the pre-and in-flight adaptability training protocols providing an integrated, multi-disciplinary countermeasure capable of fulfilling multiple requirements making it a comprehensive and cost effective countermeasure approach to enhance sensorimotor capabilities following long-duration space flight.

Mulavara, Ajitkumar; Kofman, Igor; DeDios, Yiri E.; Galvan, Raquel; Miller, Chris; Peters, Brian; Cohen, Helen; Jeevarajan, Jerome; Reschke, Millard; Wood, Scott; Bloomberg, Jacob

2014-01-01

150

Experimental observation of stochastic resonance in a solid-state ring laser in the absence of bistability  

SciTech Connect

The appearance of a stochastic resonance is found in a solid-state ring laser in the absence of bistability in it. It is shown that in this laser operating in the self-modulation regime of the first kind, the noise modulation of the pump can cause a significant increase in the laser response to the periodic modulating signal. These effects observed are explained qualitatively. (nonlinear optical phenomena)

Zolotoverkh, I I; Kravtsov, Nikolai V; Lariontsev, E G; Firsov, V V; Chekina, S N [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow (Russian Federation)

2009-09-30

151

Stochastic resonance in bistable systems with nonlinear dissipation and multiplicative noise: A microscopic approach  

NASA Astrophysics Data System (ADS)

We have studied the stochastic resonance (SR) of bistable systems coupled to a bath with a nonlinear system-bath interaction, by using the microscopic, generalized Caldeira-Leggett (CL) model. The adopted CL model yields the non-Markovian Langevin equation with nonlinear dissipation and state-dependent (multiplicative) diffusion which preserve the fluctuation-dissipation relation (FDR). Results of our simulations are given as follows: (1) the spectral power amplification (SPA) exhibits SR not only for a and b but also for ? while the stationary probability distribution function is independent of them where a and b denote magnitudes of multiplicative and additive noises, respectively, and ? expresses the relaxation time of Ornstein-Uhlenbeck (OU) colored noise; (2) the SPA for coexisting additive and multiplicative noises has a single-peak but two-peak structure as functions of a, b and/or ?. Results (1) and (2) are qualitatively different from previous ones obtained by phenomenological Langevin models where the FDR is not held or indefinite. These show an importance of the FDR in a study on SR of open bistable systems.

Hasegawa, Hideo

2013-05-01

152

Enhanced Fault Detection of Rolling Element Bearing Based on Cepstrum Editing and Stochastic Resonance  

NASA Astrophysics Data System (ADS)

By signal pre-whitening based on cepstrum editing,the envelope analysis can be done over the full bandwidth of the pre-whitened signal, and this enhances the bearing characteristic frequencies. The bearing faults detection could be enhanced without knowledge of the optimum frequency bands to demodulate, however, envelope analysis over full bandwidth brings more noise interference. Stochastic resonance (SR), which is now often used in weak signal detection, is an important nonlinear effect. By normalized scale transform, SR can be applied in weak signal detection of machinery system. In this paper, signal pre-whitening based on cepstrum editing and SR theory are combined to enhance the detection of bearing fault. The envelope spectrum kurtosis of bearing fault characteristic components is used as indicators of bearing faults. Detection results of planted bearing inner race faults on a test rig show the enhanced detecting effects of the proposed method. And the indicators of bearing inner race faults enhanced by SR are compared to the ones without enhancement to validate the proposed method.

Zhang, Xiaofei; Hu, Niaoqing; Hu, Lei; Fan, Bin; Cheng, Zhe

2012-05-01

153

Adaptive bistable stochastic resonance and its application in mechanical fault feature extraction  

NASA Astrophysics Data System (ADS)

Stochastic resonance (SR) is an important approach to detect weak vibration signals from heavy background noise. In order to increase the calculation speed and improve the weak feature detection performance, a new bistable model has been built. With this model, an adaptive and fast SR method based on dyadic wavelet transform and least square system parameters solving is proposed in this paper. By adding the second-order differential item into the traditional bistable model, noise utilization can be increased and the quality of SR output signal can be improved. The iteration algorithm for implementing the adaptive SR is given. Compared with the traditional adaptive SR method, this algorithm does not need to set up the searching range and searching step size of the system parameters, but only requires a few iterations. The proposed method, discrete wavelet transform and the traditional adaptive SR method are applied to analyzing simulated vibration signals and extracting the fault feature of a rotor system. The contrastive results verify the superiority of the proposed method, and it can be effectively applied to weak mechanical fault feature extraction.

Qin, Yi; Tao, Yi; He, Ye; Tang, Baoping

2014-12-01

154

Stochastic Resonance Whole-Body Vibration, Musculoskeletal Symptoms, and Body Balance: A Worksite Training Study  

PubMed Central

Background Stochastic resonance whole-body vibration training (SR-WBV) was tested to reduce work-related musculoskeletal complaints. Methods Participants were 54 white-collar employees of a Swiss organization. The controlled crossover design comprised two groups each given 4 weeks of exercise and no training during a second 4-week period. Outcome was daily musculoskeletal well-being, musculoskeletal pain, and surefootedness. In addition, participants performed a behavioral test on body balance prior to when SR-WBV started and after 4 weeks of SR-WBV. Results Across the 4-week training period, musculoskeletal well-being and surefootedness were significantly increased (p < 0.05), whereas musculoskeletal pain was significantly reduced only in those who reported low back pain during the last 4 weeks prior to the study (p < 0.05). Body balance was significantly increased by SR-WBV (p < 0.05). Conclusion SR-WBV seems to be an efficient option in primary prevention of musculoskeletal complaints and falls at work. PMID:24106645

Elfering, Achim; Arnold, Sibille; Schade, Volker; Burger, Christian; Radlinger, Lorenz

2013-01-01

155

Stochastic Resonance Activity Influences Serum Tryptophan Metabolism in Healthy Human Subjects  

PubMed Central

Background Stochastic resonance therapy (SRT) is used for rehabilitation of patients with various neuropsychiatric diseases. An alteration in tryptophan metabolism along the kynurenine pathway has been identified in the central and peripheral nervous systems in patients with neuroinflammatory and neurodegenerative diseases and during the aging process. This study investigated the effect of SRT as an exercise activity on serum tryptophan metabolites in healthy subjects. Methods Serum L-tryptophan, L-kynurenine, kynurenic acid, and anthranilic acid levels were measured one minute before SRT and at one, 5, 15, 30, and 60 minutes after SRT. We found that SRT affected tryptophan metabolism. Serum levels of L-tryptophan, L-kynurenine, and kynurenic acid were significantly reduced for up to 60 minutes after SRT. Anthranilic acid levels were characterized by a moderate, non significant transient decrease for up to 15 minutes, followed by normalization at 60 minutes. Tryptophan metabolite ratios were moderately altered, suggesting activation of metabolism after SRT. Lowering of tryptophan would generally involve activation of tryptophan catabolism and neurotransmitter, protein, and bone biosynthesis. Lowering of kynurenic acid by SRT might be relevant for improving symptoms in patients with neuropsychiatric disorders, such as Parkinson’s disease, Alzheimer’s disease, schizophrenia, and depression, as well as certain pain conditions. PMID:22174588

Kepplinger, Berthold; Baran, Halina; Sedlnitzky-Semler, Brenda; Badawi, Nagy-Roland; Erhart, Helene

2011-01-01

156

Plasma transport in stochastic magnetic field caused by vacuum resonant magnetic perturbations at diverted tokamak edge  

SciTech Connect

A kinetic transport simulation for the first 4 ms of the vacuum resonant magnetic perturbations (RMPs) application has been performed for the first time in realistic diverted DIII-D tokamak geometry [J. Luxon, Nucl. Fusion 42, 614 (2002)], with the self-consistent evaluation of the radial electric field and the plasma rotation. It is found that, due to the kinetic effects, the stochastic parallel thermal transport is significantly reduced when compared to the standard analytic model [A. B. Rechester and M. N. Rosenbluth, Phys. Rev. Lett. 40, 38 (1978)] and the nonaxisymmetric perpendicular radial particle transport is significantly enhanced from the axisymmetric level. These trends agree with recent experimental result trends [T. E. Evans, R. A. Moyer, K. H. Burrell et al., Nat. Phys. 2, 419 (2006)]. It is also found, as a side product, that an artificial local reduction of the vacuum RMP fields in the vicinity of the magnetic separatrix can bring the kinetic simulation results to a more detailed agreement with experimental plasma profiles.

Park, G. [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Chang, C. S. [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, 305-701 (Korea, Republic of); Joseph, I.; Moyer, R. A. [University of California at San Diego, La Jolla, California 92093 (United States)

2010-10-15

157

Electrical noise modulates perception of electrical pulses in humans: sensation enhancement via stochastic resonance.  

PubMed

Although noise is usually considered to be harmful for signal detection and information transmission, stochastic resonance (SR) describes the counterintuitive phenomenon of noise enhancing the detection and transmission of weak input signals. In mammalian sensory systems, SR-related phenomena may arise both in the peripheral and the central nervous system. Here, we investigate behavioral SR effects of subliminal electrical noise stimulation on the perception of somatosensory stimuli in humans. We compare the likelihood to detect near-threshold pulses of different intensities applied on the left index finger during presence vs. absence of subliminal noise on the same or an adjacent finger. We show that (low-pass) noise can enhance signal detection when applied on the same finger. This enhancement is strong for near-threshold pulses below the 50% detection threshold and becomes stronger when near-threshold pulses are applied as brief trains. The effect reverses at pulse intensities above threshold, especially when noise is replaced by subliminal sinusoidal stimulation, arguing for a peripheral direct current addition. Unfiltered noise applied on longer pulses enhances detection of all pulse intensities. Noise applied to an adjacent finger has two opposing effects: an inhibiting effect (presumably due to lateral inhibition) and an enhancing effect (most likely due to SR in the central nervous system). In summary, we demonstrate that subliminal noise can significantly modulate detection performance of near-threshold stimuli. Our results indicate SR effects in the peripheral and central nervous system. PMID:24353303

Iliopoulos, Fivos; Nierhaus, Till; Villringer, Arno

2014-03-01

158

Stochastic and equilibrium pictures of the ultracold Fano-Feshbach-resonance molecular conversion rate  

NASA Astrophysics Data System (ADS)

The ultracold molecular conversion rate occurring in an adiabatic ramp through a Fano-Feshbach resonance is studied and compared in two statistical models. One model, the so-called stochastic phase-space sampling (SPSS) [Hodby , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.94.120402 94, 120402 (2005)] evaluates the overlap of two atomic distributions in phase space by sampling atomic pairs according to a phase-space criterion. The other model, the chemical equilibrium theory (ChET) [Watabe and Nikuni, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.77.013616 77, 013616 (2008)] considers atomic and molecular distributions in the limit of the chemical and thermal equilibrium. The present study applies SPSS and ChET to a prototypical system of K+K? K2 in all the symmetry combinations, namely Fermi-Fermi, Bose-Bose, and Bose-Fermi cases. To examine implications of the phase-space criterion for SPSS, the behavior of molecular conversion is analyzed using four distinct geometrical constraints. Our comparison of the results of SPSS with those of ChET shows that while they appear similar in most situations, the two models give rise to rather dissimilar behaviors when the presence of a Bose-Einstein condensate strongly affects the molecule formation.

Yamakoshi, Tomotake; Watanabe, Shinichi; Zhang, Chen; Greene, Chris H.

2013-05-01

159

New measures of multimodality for the detection of a ghost stochastic resonance  

NASA Astrophysics Data System (ADS)

Large-amplitude (10-15 K) millennial-duration warming events, the Dansgaard-Oeschger (DO) events, repeatedly occurred in the North Atlantic region during ice ages. So far, the trigger of these events is not known. To explain their recurrence pattern, a ghost stochastic resonance (GSR) scenario has been suggested, i.e., a dynamical scenario in which the events represent the subharmonic response to centennial-scale solar forcing plus noise. According to this hypothesis a multimodal phase distribution of the events is expected, which should be tested on the basis of climate records by means of time series analysis. A major obstacle in these tests, however, is the need of a statistical measure of regularity that can distinguish between a random occurrence of DO events and a GSR scenario. Here we construct and compare three new measures of phase multimodality. In a Monte Carlo simulation with a simple conceptual model of DO events we simulate probability distributions of the measures under both scenarios for realizations of only 11 DO events. Based on these distributions we find that our measures are able to distinguish between a random occurrence and a GSR scenario. We further apply our measures to analyze the recurrence pattern of the last 11 DO events in the North Greenland Ice Core Project deep ice core from Greenland.

Braun, H.; Ditlevsen, P.; Kurths, J.

2009-12-01

160

Vestibular Rehabilitation Outcomes in the Elderly with Chronic Vestibular Dysfunction  

PubMed Central

Background Chronic vestibular dysfunction is a frustrating problem in the elderly and can have a tremendous impact on their life, but only a few studies are available. Vestibular rehabilitation therapy (VRT) is an important therapeutic option for the neuro-otologist in treating patients with significant balance deficits. Objectives The purpose of this study was to assess the effect of vestibular rehabilitation on dizziness in elderly patients with chronic vestibular dysfunction. Materials and Methods A total of 33 patients older than 60 years with chronic vestibular dysfunction were studied. Clinical and objective vestibular tests including videonystagmography (VNG) and dizziness handicap inventory (DHI) were carried out at their first visit, 2 weeks, and 8 weeks post-VRT. The VRT exercises were performed according to Cawthorne and Cooksey protocols. Results Oculomotor assessments were within normal limits in all patients. Nineteen patients (57.57%) showed abnormal canal paralysis on caloric testing which at follow-up sessions; CP values were decreased remarkably after VRT exercises. We found a significant improvement between pre-VRT and post-VRT total DHI scores (P < 0.001). This improvement was most prominent in functional subscore. Conclusions Our study demonstrated that VRT is an effective therapeutic method for elderly patients with chronic vestibular dysfunction. PMID:23396380

Bayat, Arash; Pourbakht, Akram; Saki, Nader; Zainun, Zuraida; Nikakhlagh, Soheila; Mirmomeni, Golshan

2012-01-01

161

Visuo-Vestibular Interactions  

NASA Technical Reports Server (NTRS)

Session TA3 includes short reports covering: (1) Vestibulo-Oculomotor Interaction in Long-Term Microgravity; (2) Effects of Weightlessness on the Spatial Orientation of Visually Induced Eye Movements; (3) Adaptive Modification of the Three-Dimensional Vestibulo-Ocular Reflex during Prolonged Microgravity; (4) The Dynamic Change of Brain Potential Related to Selective Attention to Visual Signals from Left and Right Visual Fields; (5) Locomotor Errors Caused by Vestibular Suppression; and (6) A Novel, Image-Based Technique for Three-Dimensional Eye Measurement.

1997-01-01

162

Vestibular responses to sound.  

PubMed

Research into vestibular responses to sound has evolved in four stages. The first, largely the work of Tullio in the 1920s, involved inspection of the eye, head, and postural responses to sound of alert animals with surgical fenestrae into various parts of the bony labyrinth. The second, begun in 1964 by Bickford and his group and continued by our group and then by others in the last 10 years, involves the measurement of evoked myogenic potentials to air-conducted and bone-conducted clicks and tones in normal humans. The third, begun by Mikaelian at about the same time as Bickford and continued by McCue, our group, and others, involves electrophysiological recordings of primary vestibular afferent neuron responses to sound in anesthetized animals. The fourth involves measurements of vestibulo-ocular responses to sound in humans with the Tullio phenomenon. It was begun by Minor and his group in 1998 with the observation that sound-induced nystagmus in humans, the Tullio phenomenon, aligned with the rotation axis of the superior semicircular canal. They then showed a defect in the temporal bone between the apex of the superior semicircular canal and the middle cranial fossa, which was the cause of most, if not all, cases of sound-induced nystagmus. Here some of the key observations made in each of these four stages are reviewed. PMID:15826961

Halmagyi, G M; Curthoys, I S; Colebatch, J G; Aw, S T

2005-04-01

163

Disrupted functional connectivity of the default mode network due to acute vestibular deficit  

PubMed Central

Vestibular neuritis is defined as a sudden unilateral partial failure of the vestibular nerve that impairs the forwarding of vestibular information from the labyrinth. The patient suffers from vertigo, horizontal nystagmus and postural instability with a tendency toward ipsilesional falls. Although vestibular neuritis is a common disease, the central mechanisms to compensate for the loss of precise vestibular information remain poorly understood. It was hypothesized that symptoms following acute vestibular neuritis originate from difficulties in the processing of diverging sensory information between the responsible brain networks. Accordingly an altered resting activity was shown in multiple brain areas of the task-positive network. Because of the known balance between the task-positive and task-negative networks (default mode network; DMN) we hypothesize that also the DMN is involved. Here, we employ functional magnetic resonance imaging (fMRI) in the resting state to investigate changes in the functional connectivity between the DMN and task-positive networks, in a longitudinal design combined with measurements of caloric function. We demonstrate an initially disturbed connectedness of the DMN after vestibular neuritis. We hypothesize that the disturbed connectivity between the default mode network and particular parts of the task-positive network might be related to a sustained utilization of processing capacity by diverging sensory information. The current results provide some insights into mechanisms of central compensation following an acute vestibular deficit and the importance of the DMN in this disease. PMID:25379422

Klingner, Carsten M.; Volk, Gerd F.; Brodoehl, Stefan; Witte, Otto W.; Guntinas-Lichius, Orlando

2014-01-01

164

Enhanced detection of rolling element bearing fault based on stochastic resonance  

NASA Astrophysics Data System (ADS)

Early bearing faults can generate a series of weak impacts. All the influence factors in measurement may degrade the vibration signal. Currently, bearing fault enhanced detection method based on stochastic resonance(SR) is implemented by expensive computation and demands high sampling rate, which requires high quality software and hardware for fault diagnosis. In order to extract bearing characteristic frequencies component, SR normalized scale transform procedures are presented and a circuit module is designed based on parameter-tuning bistable SR. In the simulation test, discrete and analog sinusoidal signals under heavy noise are enhanced by SR normalized scale transform and circuit module respectively. Two bearing fault enhanced detection strategies are proposed. One is realized by pure computation with normalized scale transform for sampled vibration signal, and the other is carried out by designed SR hardware with circuit module for analog vibration signal directly. The first strategy is flexible for discrete signal processing, and the second strategy demands much lower sampling frequency and less computational cost. The application results of the two strategies on bearing inner race fault detection of a test rig show that the local signal to noise ratio of the characteristic components obtained by the proposed methods are enhanced by about 50% compared with the band pass envelope analysis for the bearing with weaker fault. In addition, helicopter transmission bearing fault detection validates the effectiveness of the enhanced detection strategy with hardware. The combination of SR normalized scale transform and circuit module can meet the need of different application fields or conditions, thus providing a practical scheme for enhanced detection of bearing fault.

Zhang, Xiaofei; Hu, Niaoqing; Cheng, Zhe; Hu, Lei

2012-11-01

165

Enhanced coding in a cochlear-implant model using additive noise: Aperiodic stochastic resonance with tuning  

NASA Astrophysics Data System (ADS)

Analog electrical stimulation of the cochlear nerve (the nerve of hearing) by a cochlear implant is an effective method of providing functional hearing to profoundly deaf people. Recent physiological and computational experiments have shown that analog cochlear implants are unlikely to convey certain speech cues by the temporal pattern of evoked nerve discharges. However, these experiments have also shown that the optimal addition of noise to cochlear implant signals can enhance the temporal representation of speech cues [R. P. Morse and E. F. Evans, Nature Medicine 2, 928 (1996)]. We present a simple model to explain this enhancement of temporal representation. Our model derives from a rate equation for the mean threshold-crossing rate of an infinite set of parallel discriminators (level-crossing detectors); a system that well describes the time coding of information by a set of nerve fibers. Our results show that the optimal transfer of information occurs when the threshold level of each discriminator is equal to the root-mean-square noise level. The optimal transfer of information by a cochlear implant is therefore expected to occur when the internal root-mean-square noise level of each stimulated fiber is approximately equal to the nerve threshold. When interpreted within the framework of aperiodic stochastic resonance, our results indicate therefore that for an infinite array of discriminators, a tuning of the noise is still necessary for optimal performance. This is in contrast to previous results [Collins, Chow, and Imhoff, Nature 376, 236 (1995); Chialvo, Longtin, and Müller-Gerking, Phys. Rev. E 55, 1798 (1997)] on arrays of FitzHugh-Nagumo neurons.

Morse, Robert P.; Roper, Peter

2000-05-01

166

Remote vibrotactile noise improves light touch sensation in stroke survivors’ fingertips via stochastic resonance  

PubMed Central

Background and purpose Stroke rehabilitation does not often integrate both sensory and motor recovery. While subthreshold noise was shown to enhance sensory signal detection at the site of noise application, having a noise-generating device at the fingertip to enhance fingertip sensation and potentially enhance dexterity for stroke survivors is impractical, since the device would interfere with object manipulation. This study determined if remote application of subthreshold vibrotactile noise (away from the fingertips) improves fingertip tactile sensation with potential to enhance dexterity for stroke survivors. Methods Index finger and thumb pad sensation was measured for ten stroke survivors with fingertip sensory deficit using the Semmes-Weinstein Monofilament and Two-Point Discrimination Tests. Sensation scores were measured with noise applied at one of three intensities (40%, 60%, 80% of the sensory threshold) to one of four locations of the paretic upper extremity (dorsal hand proximal to the index finger knuckle, dorsal hand proximal to the thumb knuckle, dorsal wrist, volar wrist) in a random order, as well as without noise at beginning (Pre) and end (Post) of the testing session. Results Vibrotactile noise of all intensities and locations instantaneously and significantly improved Monofilament scores of the index fingertip and thumb tip (p?stochastic resonance and interneuronal connections. While long-term benefits of noise in stroke patients warrants further investigation, this result demonstrates potential that a wearable device applying vibrotactile noise at the wrist could enhance sensation and grip ability without interfering with object manipulation in everyday tasks. PMID:24112371

2013-01-01

167

Forster resonance energy transfer, absorption and emission spectra in multichromophoric systems: III. Exact stochastic path integral evaluation  

E-print Network

A numerically exact path integral treatment of the absorption and emission spectra of open quantum systems is presented that requires only the straightforward solution of a stochastic differential equation. The approach converges rapidly enabling the calculation of spectra of large excitonic systems across the complete range of system parameters and for arbitrary bath spectral densities. With the numerically exact absorption and emission operators one can also immediately compute energy transfer rates using the multi-chromophoric Forster resonant energy transfer formalism. Benchmark calculations on the emission spectra of two level systems are presented demonstrating the efficacy of the stochastic approach. This is followed by calculations of the energy transfer rates between two weakly coupled dimer systems as a function of temperature and system-bath coupling strength. It is shown that the recently developed hybrid cumulant expansion is the only perturbative method capable of generating uniformly reliable e...

Moix, Jeremy; Cao, Jianshu

2015-01-01

168

Vestibular function test program evaluation  

E-print Network

VESTIBULAR FUNCTION TEST PROGRAM EVALUATION A Thesis by GLENN FREDERIC SCHMIDT Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTERS OF SCIENCE May 1990 Major... Subject: Bioengineering VESTIBULAR FUNCTION TEST PROGRAM EVALUATION A Thesis by GLENN FREDERIC SCMIDT Approved as to style and content by: Charles S. Lessard (Chair of Committee) Edward M. O' Brien (Member) rry Christensen (Member) G. K le Benne...

Schmidt, Glenn Frederic

1990-01-01

169

Aging of vestibular function evaluated using correlational vestibular autorotation test  

PubMed Central

Background Imbalance from degeneration of vestibular end organs is a common problem in the elderly. However, the decline of vestibular function with aging was revealed in few vestibular function tests such as vestibular autorotation test (VAT). In the current VAT, there are drawbacks of poor test–retest reliability, slippage of the sensor at high-speed rotations, and limited data about the effect of aging. We developed a correlational-VAT (cVAT) system that included a small, light sensor (less than 20 g) with wireless data transmission technique to evaluate the aging of vestibular function. Material and methods We enrolled 53 healthy participants aged between 25 and 75 years and divided them into five age groups. The test conditions were vertical and horizontal head autorotations of frequencies from 0 to 3 Hz with closed eyes or open eyes. The cross-correlation coefficient (CCC) between eye velocity and head velocity was obtained for the head autorotations between 1 Hz and 3 Hz. The mean of the CCCs was used to represent the vestibular function. Results Age was significantly and negatively correlated with the mean CCC for all test conditions, including horizontal or vertical autorotations with open eyes or closed eyes (P<0.05). The mean CCC with open eyes declined significantly at 55–65 years old and the mean CCC with closed eyes declined significantly at 65–75 years old. Conclusion Vestibular function evaluated using mean CCC revealed a decline with age, and the function of visual-vestibulo-ocular reflex declined 10 years earlier than the function of vestibulo-ocular reflex. PMID:25214774

Hsieh, Li-Chun; Lin, Hung-Ching; Lee, Guo-She

2014-01-01

170

Vertical torque responses to vestibular stimulation in standing humans  

PubMed Central

Abstract The effects of electrical vestibular stimulation upon movement and perception suggest two evoked sensations: head roll and inter-aural linear acceleration. The head roll vector causes walking subjects to turn in a direction dependent on head pitch, requiring generation of torque around a vertical axis. Here the effect of vestibular stimulation upon vertical torque (Tz) was investigated during quiet stance. With the head tilted forward, square-wave stimuli applied to the mastoid processes evoked a polarity-specific Tz response accompanied by trunk yaw. Stochastic vestibular stimulation (SVS) was used to investigate the effect of head pitch with greater precision; the SVS–Tz cross-correlation displayed a modulation pattern consistent with the head roll vector and this was also reflected by changes in coherence at 2–3 Hz. However, a separate response at 7–8 Hz was unaffected by head pitch. Head translation (rather than rotation) had no effect upon this high frequency response either, suggesting it is not caused by a sense of body rotation induced by an inter-aural acceleration vector offset from the body. Instead, high coherence between medio-lateral shear force and Tz at the same frequency range suggests it is caused by mechanical coupling to evoked medio-lateral sway. Consistent with this explanation, the 7–8 Hz response was attenuated by 90 deg head roll or yaw, both of which uncouple the inter-aural axis from the medio-lateral sway axis. These results demonstrate two vertical torque responses to electrical vestibular stimulation in standing subjects. The high frequency response can be attributed to mechanical coupling to evoked medio-lateral sway. The low frequency response is consistent with a reaction to a sensation of head roll, and provides a novel method for investigating proprioceptive-vestibular interactions during stance. PMID:21690188

Reynolds, Raymond F

2011-01-01

171

Comparison of vestibular autorotation and caloric testing.  

PubMed

The two most common stimuli of the vestibular system for diagnostic purposes are caloric and rotational head movements. Caloric stimulation, by delivering thermal energy to the lateral semicircular canal, is a well-studied method of vestibular testing, and its clinical usefulness has been established. Vestibular autorotation testing uses high-frequency (2 to 6 Hz), active head movements to stimulate the horizontal and vertical vestibulo-ocular reflex to produce measurable eye movements that can be used to calculate gain and phase. We compared the alternate bilateral bithermal caloric results with the vestibular autorotation test results obtained from 39 patients with peripheral vestibular disorders and from 10 patients with acoustic neuroma. In the peripheral disorder group, only 2 of 14 patients with equal caloric response (< 20% reduced vestibular response) had a normal vestibular autorotation test result. No patients with a reduced vestibular response greater than 21% had a normal vestibular autorotation test result. In the acoustic neuroma group, four patients had a normal reduced vestibular response, but all patients had an abnormal vestibular autorotation test result. We conclude that testing both the horizontal and vertical vestibulo-ocular reflexes in their physiologic frequency range with the vestibular autorotation test provides additional information that could be missed by conventional caloric testing. Therefore high-frequency rotational testing is a valuable addition to the vestibular test battery. PMID:7675481

Saadat, D; O'Leary, D P; Pulec, J L; Kitano, H

1995-09-01

172

Eye movement studies with a vestibular prosthesis/  

E-print Network

Vestibular loss, which can manifest as dizziness, imbalance, or spatial disorientation, is widespread and often caused by inner ear hair cell malfunction. To address these problems, we are developing a vestibular implant ...

Saginaw, Michael A. (Michael Adlai)

2010-01-01

173

Cratered Lorentzian response of driven microwave superconducting nanowire-bridged resonators: Oscillatory and magnetic-field induced stochastic states  

NASA Astrophysics Data System (ADS)

We report on observations of a superconductor-normal pulsing regime in microwave (GHz) coplanar waveguide resonators consisting of superconducting MoGe films interrupted by a gap that is bridged by one or more suspended superconducting nanowires. This regime, which involves MHz-frequency oscillations in the amplitude of the supercurrent in the resonator, is achieved when the steady-state amplitude of the current in the driven resonator exceeds the critical current of the nanowires. Thus we are able to determine the temperature dependence of the critical current, which agrees well with the corresponding Bardeen formula. The pulsing regime manifests itself as an apparent “crater” on top of the fundamental Lorentzian peak of the resonator. Once the pulsing regime is achieved at a fixed drive power, however, it remains stable for a range of drive frequencies corresponding to subcritical steady-state currents in the resonator. We develop a phenomenological model of resonator-nanowire systems from which we are able to obtain a quantitative description of the amplitude oscillations and also, inter alia, to investigate thermal relaxation processes in superconducting nanowires. For the case of resonators comprising two parallel nanowires and subject to an external magnetic field, we find field-driven oscillations of the onset power for the amplitude oscillations, as well as the occurrence (for values of the magnetic field that strongly frustrate the nanowires) of a distinct steady state in which the pulsing is replaced by stochastic amplitude fluctuations. We conclude by giving a brief discussion of how circuit-quantum electrodynamics-based systems have the potential to facilitate nondestructive measurements of the current-phase relationship of superconducting nanowires and, hence, of the rate at which quantum phase slips take place in superconducting nanowires.

Brenner, Matthew W.; Gopalakrishnan, Sarang; Ku, Jaseung; McArdle, Timothy J.; Eckstein, James N.; Shah, Nayana; Goldbart, Paul M.; Bezryadin, Alexey

2011-05-01

174

Habituation of vestibular responses: An overview  

NASA Technical Reports Server (NTRS)

An historical survey of vestibular habituation experiments has been undertaken. Methodological problems are presented briefly, and the influence of arousal on vestibular responses is detailed. Data obtained from animals and from man are treated separately. At least for man, the term habituation may be better defined by a dynamic change in the form of vestibular responses than by a simple response reduction.

Collins, W. E.

1973-01-01

175

Comparison of vestibular autorotation and caloric testing  

Microsoft Academic Search

The two most common stimuli of the vestibular system for diagnostic purposes are caloric and rotational head movements. Caloric stimulation, by delivering thermal energy to the lateral semicircular canal, is a well-studied method of vestibular testing, and its clinical usefulness has been established. Vestibular autorotation testing uses high-frequency (2 to 6 Hz), active head movements to stimulate the horizontal and

DARYOUSH SAADAT; DENNIS P. O'LEARY; JACK L. PULEC; HIROYA KITANO

1995-01-01

176

Vestibular modulation of spatial perception  

PubMed Central

Vestibular inputs make a key contribution to the sense of one’s own spatial location. While the effects of vestibular stimulation on visuo-spatial processing in neurological patients have been extensively described, the normal contribution of vestibular inputs to spatial perception remains unclear. To address this issue, we used a line bisection task to investigate the effects of galvanic vestibular stimulation (GVS) on spatial perception, and on the transition between near and far space. Brief left-anodal and right-cathodal GVS or right-anodal and left-cathodal GVS were delivered. A sham stimulation condition was also included. Participants bisected lines of different lengths at six distances from the body using a laser pointer. Consistent with previous results, our data showed an overall shift in the bisection bias from left to right as viewing distance increased. This pattern suggests leftward bias in near space, and rightward bias in far space. GVS induced strong polarity dependent effects in spatial perception, broadly consistent with those previously reported in patients: left-anodal and right-cathodal GVS induced a leftward bisection bias, while right-anodal and left-cathodal GVS reversed this effect, and produced bisection bias toward the right side of the space. Interestingly, the effects of GVS were comparable in near and far space. We speculate that vestibular-induced biases in space perception may optimize gathering of information from different parts of the environment. PMID:24133440

Ferrč, Elisa R.; Longo, Matthew R.; Fiori, Federico; Haggard, Patrick

2013-01-01

177

Vestibular function in superficial siderosis  

PubMed Central

Background Superficial siderosis (SS) is caused by repeated or continuous bleeding into the subarachnoid space that results in iron from hemoglobin (hemosiderin) being deposited on the surface of the brain. Clinically, the condition is characterized by sensorineural deafness, ataxia, and pyramidal signs. However the mechanism of peripheral vestibular disturbance was not revealed. We show the vestibular function of SS patients, and shed light on saccule-inferior vestibular nerve. Methods Over the past 9 years, 5 patients were definitively diagnosed with SS by MRI in our department. These patients were subjected to balance testing. Results Vestibular evoked myogenic potential (VEMP) was observed in patients who had suffered from SS for a short period but tended to be diminished or absent in patients who had suffered from the condition for a longer period. Conclusions These findings in SS patients suggest that saccule-inferior vestibular function is maintained at early stages of the disorder. Our study may help to clarify the mechanism of SS. PMID:23617695

2013-01-01

178

Vestibular schwannoma surgery and headache.  

PubMed

The aim of the study was to evaluate aetiological factors for postoperative headache after vestibular schwannoma (VS) surgery with respect to asymmetric activation of vestibular reflexes. After surgery, 27 VS patients with persistent postoperative headache, 16 VS patients without headache and 9 healthy controls were examined. The vestibular, cervicocollic and cervicospinal reflexes were evaluated to study whether asymmetric activation of vestibular reflexes could cause headache. The effect of neck muscle and occipital nerve anaesthesia and the effect of sumatriptan on headache were also evaluated. The vestibular function of VS patients with headache did not differ from that of VS patients without headache, but was abnormal when compared to that of normal controls. The cervicospinal and cervicocollic reflexes did not differ in the patient groups. Injection of lidocaine around the operation scar gave pain relief to two patients, and one of them had occipital nerve entrapment. Infiltration of lidocaine deep in the neck muscles in the vicinity of the C2 root did not alleviate headache, but caused vertigo. Nine patients with musculogenic headache got pain relief from supportive neck collars, and two patients with cervicobrachial syndrome got pain relief from manual neck traction. The study shows that asymmetric activation of cervicocollic reflexes does not seem to be the reason for headache. Headache seems to be linked to neuropathic pain, allegedly caused by trigeminal irritation of the inner ear and the posterior fossa, which has recently been linked to vascular pain. PMID:10908966

Levo, H; Blomstedt, G; Pyykkö, I

2000-01-01

179

Procedures for restoring vestibular disorders  

PubMed Central

This paper will discuss therapeutic possibilities for disorders of the vestibular organs and the neurons involved, which confront ENT clinicians in everyday practice. Treatment of such disorders can be tackled either symptomatically or causally. The possible strategies for restoring the body's vestibular sense, visual function and co-ordination include medication, as well as physical and surgical procedures. Prophylactic or preventive measures are possible in some disorders which involve vertigo (bilateral vestibulopathy, kinetosis, height vertigo, vestibular disorders when diving (Tables 1 (Tab. 1) and 2 (Tab. 2)). Glucocorticoid and training therapy encourage the compensation of unilateral vestibular loss. In the case of a bilateral vestibular loss, it is important to treat the underlying disease (e.g. Cogan's disease). Although balance training does improve the patient's sense of balance, it will not restore it completely. In the case of Meniere's disease, there are a number of medications available to either treat bouts or to act as a prophylactic (e.g. dimenhydrinate or betahistine). In addition, there are non-ablative (sacculotomy) as well as ablative surgical procedures (e.g. labyrinthectomy, neurectomy of the vestibular nerve). In everyday practice, it has become common to proceed with low risk therapies initially. The physical treatment of mild postural vertigo can be carried out quickly and easily in outpatients (repositioning or liberatory maneuvers). In very rare cases it may be necessary to carry out a semicircular canal occlusion. Isolated disturbances of the otolith function or an involvement of the otolith can be found in roughly 50% of labyrinth disturbances. A specific surgical procedure to selectively block the otolith organs is currently being studied. When an external perilymph fistula involving loss of perilymph is suspected, an exploratory tympanotomy involving also the round and oval window niches must be carried out. A traumatic rupture of the round window membrane can, for example, also be caused by an implosive inner ear barotrauma during the decompression phase of diving. Dehiscence of the anterior semicircular canal, a relatively rare disorder, can be treated conservatively (avoiding stimuli which cause dizziness), by non-ablative „resurfacing" or by „plugging" the semicircular canal. A perilymph fistula can cause a Tullio-phenomenon resulting from a traumatic dislocation or hypermobility of the stapes, which can be surgically corrected. Vestibular disorders can also result from otosurgical therapy. When balance disorders persist following stapedectomy it is necessary to carry out a revision operation in order to either exclude a perilymph fistula or shorten the piston. Surgically reducing the size of open mastoid cavities (using for example porous hydroxylapatite or cartilage) can result in a reduction of vertiginous symptoms while nursing or during exposure to ambient air. Vestibular disturbances can occur both before and after vestibular nerve surgery (acoustic neuroma). Initially, good vestibular compensation can be expected after surgically removing the acoustic neuroma. An aberrant regeneration of nerve fibers of the vestibulocochlear nerve has been suggested as a cause for secondary worsening. Episodes of vertigo can be caused by an irritation of the vestibular nerve (vascular loop). Neurovascular decompression is generally regarded as the best surgical therapy. In the elderly, vestibular disturbances can severely limit quality of life and are often aggravated by multiple comorbidities. Antivertiginous drugs (e.g. dimenhydrinate) in combination with movement training can significantly reduce symptoms. Administering antivertiginous drugs over varying periods of time (e.g. transdermal scopolamine application via patches) as well as kinetosis training can be used as both prophylactically and as a therapy for kinetosis. Exposure training should be used as a prophylactic for height vertigo. PMID:22073053

Walther, Leif Erik

2005-01-01

180

Large deviations for diffusions with time periodic drift and stochastic resonance  

E-print Network

trajectories follow the exterior periodic motion in an optimal fashion, i.e. for some optimal intensity (T al. [3] proposed a simple stochastic climate model based on an energy balance equation to periodic changes of the earth orbit's eccentricity (Milankovich cycles), which coincide roughly

Imkeller, Peter

181

Large deviations for di#usions with time periodic drift and stochastic resonance  

E-print Network

trajectories follow the exterior periodic motion in an optimal fashion, i.e. for some optimal intensity #(T] proposed a simple stochastic climate model based on an energy balance equation for the averaged global(t) fluctuates periodically at a very low frequency of 10 -5 times per year due to periodic changes of the earth

Imkeller, Peter

182

Stochastic resonance in catalytic reduction of NO with CO on Pt,,100... Lingfa Yang, Zhonghuai Hou, Baojing Zhou, and Houwen Xina)  

E-print Network

Stochastic resonance in catalytic reduction of NO with CO on Pt,,100... Lingfa Yang, Zhonghuai Hou In the past, catalytic reduction of NO with CO has been thoroughly investigated on Pt single crystal.1 low pressure on Pt 100 ,5 and no oscillation was found on the other low-index surfaces 110 or 111

Yang, Lingfa

183

A kinetic and kinematic analysis of the effect of stochastic resonance electrical stimulation and knee sleeve during gait in osteoarthritis of the knee.  

PubMed

Extended use of knee sleeves in populations at risk for knee osteoarthritis progression has shown functional and quality of life benefits; however, additional comprehensive kinematic and kinetic analyses are needed to determine possible physical mechanisms of these benefits which may be due to the sleeve's ability to enhance knee proprioception. A novel means of extending these enhancements may be through stochastic resonance stimulation. Our goal was to determine whether the use of a knee sleeve alone or combined with stochastic resonance electrical stimulation improves knee mechanics in knee osteoarthritis. Gait kinetics and kinematics were assessed in subjects with medial knee osteoarthritis when presented with four conditions: control1, no electrical stimulation/sleeve, 75% threshold stimulation/sleeve, and control2. An increase in knee flexion angle throughout stance and a decrease in flexion moment occurring immediately after initial contact were seen in the stimulation/sleeve and sleeve alone conditions; however, these treatment conditions did not affect the knee adduction angle and internal knee abduction moment during weight acceptance. No differences were found between the sleeve alone and the stochastic resonance with sleeve conditions. A knee sleeve can improve sagittal-plane knee kinematics and kinetics, although adding the current configuration of stochastic resonance did not enhance these effects. PMID:23878205

Collins, Amber; Blackburn, Troy; Olcott, Chris; Jordan, Joanne M; Yu, Bing; Weinhold, Paul

2014-02-01

184

First cross-correlation analysis of interferometric and resonant-bar gravitational-wave data for stochastic backgrounds  

Microsoft Academic Search

Data from the {LIGO} Livingston interferometer and the\\u000a\\u0009\\u0009 ALLEGRO resonant-bar detector, taken during {LIGO}'s fourth\\u000a\\u0009\\u0009 science run, were examined for cross correlations\\u000a\\u0009\\u0009 indicative of a stochastic gravitational-wave background in\\u000a\\u0009\\u0009 the frequency range 850-950 Hz, with most of the\\u000a\\u0009\\u0009 sensitivity arising between 905 and 925 Hz. ALLEGRO was\\u000a\\u0009\\u0009 operated in three different orientations during the\\u000a\\u0009\\u0009 experiment to modulate the relative sign

B. Abbott; R. Abbott; R. Adhikari; J. Agresti; P. Ajith; B. Allen; R. Amin; S. B. Anderson; W. G. Anderson; M. Arain; M. Araya; H. Armandula; M. Ashley; S. Aston; P. Aufmuth; C. Aulbert; S. Babak; S. Ballmer; H. Bantilan; B. C. Barish; C. Barker; D. Barker; B. Barr; P. Barriga; M. A. Barton; K. Bayer; K. Belczynski; J. Betzwieser; P. T. Beyersdorf; B. Bhawal; I. A. Bilenko; G. Billingsley; R. Biswas; E. Black; K. Blackburn; L. Blackburn; D. Blair; B. Bland; J. Bogenstahl; L. Bogue; R. Bork; V. B. Braginsky; S. Bose; P. R. Brady; J. E. Brau; M. Brinkmann; A. Bunkowski; D. A. Brown; A. Bullington; A. Buonanno; M. Burgamy; O. Burmeister; D. Busby; R. L. Byer; L. Cadonati; G. Cagnoli; J. B. Camp; J. Cannizzo; K. Cannon; C. A. Cantley; J. Cao; L. Cardenas; M. M. Casey; G. Castaldi; C. Cepeda; E. Chalkey; P. Charlton; S. Chatterji; S. Chelkowski; Y. Chen; F. Chiadini; D. Chin; E. Chin; J. Chow; N. Christensen; J. Clark; P. Cochrane; T. Cokelaer; C. N. Colacino; R. Coldwell; R. Conte; D. Cook; A. M. Cruise; A. Cumming; J. Dalrymple; E. D'Ambrosio; K. Danzmann; G. Davies; D. DeBra; J. Degallaix; M. Degree; T. Demma; V. Dergachev; S. Desai; R. DeSalvo; S. Dhurandhar; M. Diaz; J. Dickson; A. Di Credico; G. Diederichs; A. Dietz; E. E. Doomes; R. W. P. Drever; J.-C. Dumas; R. J. Dupuis; J. G. Dwyer; P. Ehrens; E. Espinoza; T. Etzel; M. Evans; T. Evans; S. Fairhurst; Y. Fan; D. Fazi; M. M. Fejer; Lee Samuel Finn; V. Fiumara; N. Fotopoulos; A. Franzen; K. Y. Franzen; A. Freise; R. Frey; T. Fricke; P. Fritschel; V. V. Frolov; M. Fyffe; V. Galdi; J. Garofoli; I. Gholami; S. Giampanis; K. D. Giardina; E. Goetz; L. Goggin; G. Gonzalez; S. Gossler; A. Grant; S. Gras; C. Gray; M. Gray; J. Greenhalgh; A. M. Gretarsson; R. Grosso; H. Grote; S. Grunewald; M. Guenther; R. Gustafson; B. Hage; W. O. Hamilton; D. Hammer; C. Hanna; J. Hanson; G. Harry; E. Harstad; T. Hayler; J. Heefner; I. S. Heng; A. Heptonstall; M. Heurs; M. Hewitson; S. Hild; E. Hirose; D. Hoak; D. Hosken; J. Hough; E. Howell; D. Hoyland; S. H. Huttner; D. Ingram; E. Innerhofer; M. Ito; Y. Itoh; A. Ivanov; D. Jackrel; B. Johnson; W. W. Johnson; D. I. Jones; G. Jones; R. Jones; L. Ju; P. Kalmus; V. Kalogera; D. Kasprzyk; E. Katsavounidis; K. Kawabe; S. Kawamura; F. Kawazoe; W. Kells; D. G. Keppel; F. Ya. Khalili; C. Kim; P. King; J. S. Kissel; S. Klimenko; K. Kokeyama; V. Kondrashov; R. K. Kopparapu; D. Kozak; B. Krishnan; P. Kwee; P. K. Lam; M. Landry; B. Lantz; A. Lazzarini; B. Lee; M. Lei; J. Leiner; V. Leonhardt; I. Leonor; K. Libbrecht; P. Lindquist; N. A. Lockerbie; M. Longo; M. Lormand; M. Lubinski; H. Lueck; B. Machenschalk; M. MacInnis; M. Mageswaran; K. Mailand; M. Malec; V. Mandic; S. Marano; S. Marka; J. Markowitz; E. Maros; I. Martin; J. N. Marx; K. Mason; L. Matone; V. Matta; N. Mavalvala; R. McCarthy; B. J. McCaulley; D. E. McClelland; S. C. McGuire; M. McHugh; K. McKenzie; J. W. C. McNabb; S. McWilliams; T. Meier; A. Melissinos; G. Mendell; R. A. Mercer; S. Meshkov; E. Messaritaki; C. J. Messenger; D. Meyers; E. Mikhailov; P. Miller; S. Mitra; V. P. Mitrofanov; G. Mitselmakher; R. Mittleman; O. Miyakawa; S. Mohanty; V. Moody; G. Moreno; K. Mossavi; C. MowLowry; A. Moylan; D. Mudge; G. Mueller; S. Mukherjee; H. Mueller-Ebhardt; J. Munch; P. Murray; E. Myers; J. Myers; T. Nash; D. Nettles; G. Newton; A. Nishizawa; K. Numata; B. O'Reilly; R. O'Shaughnessy; D. J. Ottaway; H. Overmier; B. J. Owen; H.-J. Paik; Y. Pan; M. A. Papa; V. Parameshwaraiah; P. Patel; M. Pedraza; S. Penn; V. Pierro; I. M. Pinto; M. Pitkin; H. Pletsch; M. V. Plissi; F. Postiglione; R. Prix; V. Quetschke; F. Raab; D. Rabeling; H. Radkins; R. Rahkola; N. Rainer; M. Rakhmanov; M. Ramsunder; K. Rawlins; S. Ray-Majumder; V. Re; H. Rehbein; S. Reid; D. H. Reitze; L. Ribichini; R. Riesen; K. Riles; B. Rivera; N. A. Robertson; C. Robinson; E. L. Robinson; S. Roddy; A. Rodriguez; A. M. Rogan; J. Rollins; J. D. Romano; J. Romie; R. Route; L. Ruet; P. Russell; K. Ryan; S. Sakata; M. Samidi; L. Sancho de la Jordana; V. Sandberg; V. Sannibale; S. Saraf; P. Sarin; B. S. Sathyaprakash; S. Sato; P. R. Saulson; R. Savage; P. Savov; S. Schediwy; R. Schilling; R. Schnabel; R. Schofield; B. F. Schutz; P. Schwinberg; S. M. Scott; A. C. Searle; B. Sears; F. Seifert; D. Sellers; A. S. Sengupta; D. H. Shoemaker; A. Sibley; J. A. Sidles; X. Siemens; A. M. Sintes; B. J. J. Slagmolen; J. Slutsky; J. R. Smith; M. R. Smith; K. Somiya; K. A. Strain; D. M. Strom; A. Stuver; T. Z. Summerscales; K.-X. Sun; P. J. Sutton; H. Takahashi; D. B. Tanner; M. Tarallo; R. Taylor; J. Thacker; K. A. Thorne; K. S. Thorne; A. Thuering; K. V. Tokmakov; C. Torres; C. Torrie; G. Traylor; M. Trias; W. Tyler; D. Ugolini; C. Ungarelli; K. Urbanek; H. Vahlbruch; M. Vallisneri; C. Van Den Broeck; M. Varvella; S. Vass; A. Vecchio; J. Veitch; P. Veitch; A. Villar; S. P. Vyachanin; S. J. Waldman; L. Wallace; H. Ward

2007-01-01

185

[Overview: diagnosis of vestibular syndromes].  

PubMed

Vestibular syndromes are one of the commonest paroxysmal disorders in our clinical practice. These consist of vertigo, oculomotor abnormalities (nystagmus), postural changes and nausea/vomiting. Vertigo can be classified as real vertigo and dizziness, based upon the presence of clinical rotatory perception. In order to diagnose a responsible lesion for various central and peripheral vestibular syndromes, we have to carefully observe nystagmus in patients with acute vertigo. Gaze-evoked nystagmus is the most important nystagmus in patients with the central vestibular syndromes. The finding is easily found at the bed side examination. In order to keep a velocity-position neural signal such as gaze holding, the neural structure to hold and maintain the neural command for a saccade is hypothesized and this has been called as the brainstem neural integrator, which sends tonic-step commands for eccentric gaze. If this fails then the integrator becomes leaky and the eyes drift back to the central position. This movement necessitates corrective saccades, hence gaze-evoked nystagmus will ensue. Vertical nystagmus such as primary position upbeat or downbeat nystagmus is also seen only in the central vestibular syndromes. The detection and diagnosis of these characteristic nystagmus are essential for primary clinicians who care patients with acute vertigo. PMID:22277489

Hirose, Genjiro

2011-11-01

186

The Vestibular Implant: Quo Vadis?  

PubMed Central

Objective: To assess the progress of the development of the vestibular implant (VI) and its feasibility short-term. Data sources: A search was performed in Pubmed, Medline, and Embase. Key words used were “vestibular prosth*” and “VI.” The only search limit was language: English or Dutch. Additional sources were medical books, conference lectures and our personal experience with per-operative vestibular stimulation in patients selected for cochlear implantation. Study selection: All studies about the VI and related topics were included and evaluated by two reviewers. No study was excluded since every study investigated different aspects of the VI. Data extraction and synthesis: Data was extracted by the first author from selected reports, supplemented by additional information, medical books conference lectures. Since each study had its own point of interest with its own outcomes, it was not possible to compare data of different studies. Conclusion: To use a basic VI in humans seems feasible in the very near future. Investigations show that electric stimulation of the canal nerves induces a nystagmus which corresponds to the plane of the canal which is innervated by the stimulated nerve branch. The brain is able to adapt to a higher baseline stimulation, while still reacting on a dynamic component. The best response will be achieved by a combination of the optimal stimulus (stimulus profile, stimulus location, precompensation), complemented by central vestibular adaptation. The degree of response will probably vary between individuals, depending on pathology and their ability to adapt. PMID:21991260

van de Berg, Raymond; Guinand, Nils; Stokroos, Robert J.; Guyot, Jean-Philippe; Kingma, Herman

2011-01-01

187

Vestibular Effects of Cochlear Implantation  

Microsoft Academic Search

Objectives\\/Hypothesis: Cochlear implantation (CI) carries with it the potential risk for vestibular system insult or stimulation with resultant dysfunc- tion. As candidate profiles continue to evolve and with the recent development of bilateral CI, under- standing the significance of this risk takes on an in- creasing importance. Study Design: Between 1997 to 2001, a prospective observational study was carried out

Craig A. Buchman; Jennifer Joy; Annelle Hodges; Fred F. Telischi; Thomas J. Balkany

2004-01-01

188

Current treatment options in vestibular migraine.  

PubMed

Approximately 1% of the general population in western industrialized countries suffers from vestibular migraine. However, it remains widely unknown and often under diagnosed despite the recently published diagnostic criteria for vestibular migraine. Treatment trials that specialize on vestibular migraine are scarce and systematic randomized controlled clinical trials are now only emerging. This review summarizes the knowledge on the currently available treatment options that were tested specifically for vestibular migraine and gives an evidence-based, informed treatment recommendation with all its limitations. To date only two randomized controlled treatment trials provide limited evidence for the use of rizatriptan and zolmitriptan for the treatment of vestibular migraine attacks because of methodological shortcomings. There is an ongoing multicenter randomized placebo-controlled trial testing metoprolol 95?mg vs. placebo (PROVEMIG-trial). Therefore, the therapeutic recommendations for the prophylactic treatment of vestibular migraine are currently widely based on the guidelines of migraine with and without aura as well as expert opinion. PMID:25538676

Obermann, Mark; Strupp, Michael

2014-01-01

189

Current Treatment Options in Vestibular Migraine  

PubMed Central

Approximately 1% of the general population in western industrialized countries suffers from vestibular migraine. However, it remains widely unknown and often under diagnosed despite the recently published diagnostic criteria for vestibular migraine. Treatment trials that specialize on vestibular migraine are scarce and systematic randomized controlled clinical trials are now only emerging. This review summarizes the knowledge on the currently available treatment options that were tested specifically for vestibular migraine and gives an evidence-based, informed treatment recommendation with all its limitations. To date only two randomized controlled treatment trials provide limited evidence for the use of rizatriptan and zolmitriptan for the treatment of vestibular migraine attacks because of methodological shortcomings. There is an ongoing multicenter randomized placebo-controlled trial testing metoprolol 95?mg vs. placebo (PROVEMIG-trial). Therefore, the therapeutic recommendations for the prophylactic treatment of vestibular migraine are currently widely based on the guidelines of migraine with and without aura as well as expert opinion. PMID:25538676

Obermann, Mark; Strupp, Michael

2014-01-01

190

Visual mental imagery during caloric vestibular stimulation  

PubMed Central

We investigated high-resolution mental imagery and mental rotation, while the participants received caloric vestibular stimulation. High-resolution visual mental imagery tasks have been shown to activate early visual cortex, which is deactivated by vestibular input. Thus, we predicted that vestibular stimulation would disrupt high-resolution mental imagery; this prediction was confirmed. In addition, mental rotation tasks have been shown to activate posterior parietal cortex, which is also engaged in the processing of vestibular stimulation. As predicted, we also found that mental rotation is impaired during vestibular stimulation. In contrast, such stimulation did not affect performance of a low-imagery control task. These data document previously unsuspected interactions between the vestibular system and the high-level visual system. PMID:15896815

Mast, Fred W.; Merfeld, Daniel M.; Kosslyn, Stephen M.

2006-01-01

191

Personality changes in patients with vestibular dysfunction.  

PubMed

The vestibular system is a sensory system that has evolved to detect linear and angular acceleration of the head in all planes so that the brain is not predominantly reliant on visual information to determine self-motion. Since the vestibular system first evolved in invertebrate species in order to detect gravitational vertical, it is likely that the central nervous system has developed a special dependence upon vestibular input. In addition to the deficits in eye movement and postural reflexes that occur following vestibular dysfunction, there is convincing evidence that vestibular loss also causes cognitive and emotional disorders, some of which may be due to the reflexive deficits and some of which are related to the role that ascending vestibular pathways to the limbic system and neocortex play in the sense of spatial orientation. Beyond this, however, patients with vestibular disorders have been reported to experience other personality changes that suggest that vestibular sensation is implicated in the sense of self. These are depersonalization and derealization symptoms such as feeling "spaced out", "body feeling strange" and "not feeling in control of self". We propose in this review that these symptoms suggest that the vestibular system may make a unique contribution to the concept of self through information regarding self-motion and self-location that it transmits, albeit indirectly, to areas of the brain such as the temporo-parietal junction (TPJ). PMID:24194706

Smith, Paul F; Darlington, Cynthia L

2013-01-01

192

Finding physiological responses in vestibular evoked potentials.  

PubMed

Vestibular prostheses are regarded as a promising tool to restore lost sensation in patients with vestibular disorders. These prostheses often electrically stimulate the vestibular nerve and stimulation efficacy is evaluated by measuring the vestibulo-ocular reflex (VOR). However, eye movement recording as intuitive metric of vestibular functionality is difficult to obtain outside the laboratory environment, and hence not available as an error signal in a closed-loop prosthesis. Recently we investigated vestibular evoked potentials (VEPs) by stimulating and recording in the same semicircular canal of a guinea pig. Here we studied the correlation between VOR and one region of VEP. We further analyzed a second portion of VEP, where vestibular nerve activity should occur using rectified bin integration (RBI). To this end, stimulation artifact was significantly reduced by hardware and software approaches. We found a high VEP-VOR correlation (R-squared=0.86), suggesting that VEP could substitute VOR as metric of vestibular function. Differences between below and above vestibular threshold stimulation were seen for the second portion of VEP. Further investigations are required to determine the specific parts of VEP that accurately represents vestibular function(s). PMID:22254790

Nguyen, T A K; Kogler, V; DiGiovanna, J; Micera, S

2011-01-01

193

A vestibular phenotype for Waardenburg syndrome?  

NASA Technical Reports Server (NTRS)

OBJECTIVE: To investigate vestibular abnormalities in subjects with Waardenburg syndrome. STUDY DESIGN: Retrospective record review. SETTING: Tertiary referral neurotology clinic. SUBJECTS: Twenty-two adult white subjects with clinical diagnosis of Waardenburg syndrome (10 type I and 12 type II). INTERVENTIONS: Evaluation for Waardenburg phenotype, history of vestibular and auditory symptoms, tests of vestibular and auditory function. MAIN OUTCOME MEASURES: Results of phenotyping, results of vestibular and auditory symptom review (history), results of vestibular and auditory function testing. RESULTS: Seventeen subjects were women, and 5 were men. Their ages ranged from 21 to 58 years (mean, 38 years). Sixteen of the 22 subjects sought treatment for vertigo, dizziness, or imbalance. For subjects with vestibular symptoms, the results of vestibuloocular tests (calorics, vestibular autorotation, and/or pseudorandom rotation) were abnormal in 77%, and the results of vestibulospinal function tests (computerized dynamic posturography, EquiTest) were abnormal in 57%, but there were no specific patterns of abnormality. Six had objective sensorineural hearing loss. Thirteen had an elevated summating/action potential (>0.40) on electrocochleography. All subjects except those with severe hearing loss (n = 3) had normal auditory brainstem response results. CONCLUSION: Patients with Waardenburg syndrome may experience primarily vestibular symptoms without hearing loss. Electrocochleography and vestibular function tests appear to be the most sensitive measures of otologic abnormalities in such patients.

Black, F. O.; Pesznecker, S. C.; Allen, K.; Gianna, C.

2001-01-01

194

Vestibular evaluation in Behçet's disease. Personal experience.  

PubMed

Few reports have appeared in the literature concerning vestibular findings in Behçet's disease. In the present study, extensive vestibular testing, performed in 14 patients (8 male, 6 female; mean age: 32 years; range: 12-51) presenting definite Behçet's disease, revealed a high prevalence of central vestibular dysfunctions (78%). Data reported here suggest that an otoneurological evaluation of Behçet's disease patients may be helpful in identifying unexpected vestibular dysfunctions and central nervous system involvement different from the classical manifestations of the neuro-Behçet's syndrome. PMID:15871606

Cadoni, G; Agostino, S; Manganelli, C; Scipione, S; Turco, S; Focosi, F; Ottaviani, F

2004-10-01

195

Personality changes in patients with vestibular dysfunction  

PubMed Central

The vestibular system is a sensory system that has evolved to detect linear and angular acceleration of the head in all planes so that the brain is not predominantly reliant on visual information to determine self-motion. Since the vestibular system first evolved in invertebrate species in order to detect gravitational vertical, it is likely that the central nervous system has developed a special dependence upon vestibular input. In addition to the deficits in eye movement and postural reflexes that occur following vestibular dysfunction, there is convincing evidence that vestibular loss also causes cognitive and emotional disorders, some of which may be due to the reflexive deficits and some of which are related to the role that ascending vestibular pathways to the limbic system and neocortex play in the sense of spatial orientation. Beyond this, however, patients with vestibular disorders have been reported to experience other personality changes that suggest that vestibular sensation is implicated in the sense of self. These are depersonalization and derealization symptoms such as feeling “spaced out”, “body feeling strange” and “not feeling in control of self”. We propose in this review that these symptoms suggest that the vestibular system may make a unique contribution to the concept of self through information regarding self-motion and self-location that it transmits, albeit indirectly, to areas of the brain such as the temporo-parietal junction (TPJ). PMID:24194706

Smith, Paul F.; Darlington, Cynthia L.

2013-01-01

196

Vestibular Function Research aboard Spacelab  

NASA Technical Reports Server (NTRS)

NASA is planning to perform a series of Vestibular Function Research (VFR) investigations on the early STS missions to investigate those neurosensory and related physiological processes believed to be associated with the space flight nausea syndrome. The first flight is scheduled for the 1981 Spacelab III Mission in which four frog specimens, mounted on a frog tilting/centrifuge device, will be subjected to periodic acceleration stimuli and periods of artificial gravity. The vestibular nerve firing responses of each frog specimen will be monitored through implanted neutral bouyancy microelectrodes and transmitted to the ground for quick analysis during the flight. The experimentation will be directed at investigating: (1) adaptation to weightlessness; (2) response to acceleration stimuli; (3) response to artificial gravity (in a weightlessness environment) and (4) readaptation to earth's gravity upon return.

Mah, R. W.; Daunton, N. G.

1978-01-01

197

Vestibular cues and virtual environments  

Microsoft Academic Search

The vast majority of virtual environments concentrate on constructing a realistic visual simulation while ignoring non-visual environmental cues. Although these missing cues can to some extent be ignored by an operator, the lack of appropriate cues may contribute to cybersickness and may affect operator performance. We examine the role of vestibular cues to self-motion on an operator's sense of self-motion

Laurence Harris; Michael Jenkin; Daniel C. Zikovitz

1998-01-01

198

[Vestibular disorders in old age].  

PubMed

The elderly show a general reduction of their bodily and mental reactions. They become slower to react and their sensory ability decreases, e.g. hearing, vision, smell and taste. With increasing age, disturbances of the balance system are found more frequently, resulting in dysequilibrium, vertigo, lightheadedness and falling. We investigated the physiological changes in the vestibular system associated with the ageing processes. We selected 470 patients aged from 1-90 years from 1500 routine neurological patients. All of these patients underwent a routine neuro-otological test battery including vestibular-spinal, caloric, rotatory and optokinetic tests with electronystagmographic recording. Vestibular ocular reactions change markedly over nine decades. The nystagmus reactions, expressed by frequency, amplitude and maximal slow phase velocity of children differ from those of adults and even more from those of the elderly. The quantitative nystagmus dynamics after caloric and rotatory stimulation are accompanied by qualitative changes of the nystagmus signal. With increasing age destructive signs appear which may produce unreadable electronystagmograms. The standing and moving pattern of the elderly patient is characterized by instability, slowness, tremor and ataxia. The results of the Romberg test show an increase of instability and unsteadiness in older patients. The Unterberger test, recorded by craniocorpography, demonstrates an increase of atactic patterns with increasing age. These changes are the result of age-related physiological changes in the sensory, cerebral, peripheral nervous and muscular systems. PMID:1794960

Aust, G

1991-12-01

199

Advances in Auditory and Vestibular Medicine.  

PubMed

Auditory and Vestibular medicine is becoming more accepted as a specialty of its own, Medical NeurOtology. Recent advances in the field have been instrumental in the understanding of the scientific foundations, pathophysiology, clinical approach and management of patients with hearing and vestibular disorders. This paper will review these advances. PMID:20711412

Hamid, Mohamed A; Trune, Dennis R; Dutia, Mayank B

2009-12-01

200

Advances in Auditory and Vestibular Medicine  

PubMed Central

Auditory and Vestibular medicine is becoming more accepted as a specialty of its own, Medical NeurOtology. Recent advances in the field have been instrumental in the understanding of the scientific foundations, pathophysiology, clinical approach and management of patients with hearing and vestibular disorders. This paper will review these advances. PMID:20711412

Trune, Dennis R.; Dutia, Mayank B.

2010-01-01

201

Vestibular-visual interactions in flight simulators  

NASA Technical Reports Server (NTRS)

The following research work is reported: (1) vestibular-visual interactions; (2) flight management and crew system interactions; (3) peripheral cue utilization in simulation technology; (4) control of signs and symptoms of motion sickness; (5) auditory cue utilization in flight simulators, and (6) vestibular function: Animal experiments.

Clark, B.

1977-01-01

202

Stochastic resonance of charge carrier diffusion in a nonhomogeneous medium in the presence of an harmonic external potential  

NASA Astrophysics Data System (ADS)

The dynamics of charge carriers (electrons) hopping through a nonhomogeneous medium in semiconductor layer is investigated by changing a thermal noise of strength D and an external harmonic potential V(x). The nonhomogeneous medium exhibits denser trap distribution around the center, which biases the electrons to therein concentrate. Applying also a monostable potential at the center further enhances the accumulation of electrons. However, by applying a nonhomogeneous hot temperature in the vicinity of the potential minimum forced the electrons to diffuse away from the center and redistribute around two points. Thermally activated rate of hopping and diffusion of electrons in a nonhomogeneous medium, as a function of model parameters, is also considered in the high barrier limit. Using two states approximation, I have also studied the stochastic resonance (SR) of the electrons dynamics in the presence of a time-varying signal. I found a strong spectral amplification ? and lower temperature occurrence of its peak as compared to previous works [M. Asfaw, B. Aragie and M. Bekele, Eur. Phys. J. B 79, 371 (2011); B. Aragie, Y. B. Tateka and M. Bekele, Eur. Phys. J. B 87, 101 (2014)].

Aragie, Berhanu

2014-10-01

203

An improved multiscale noise tuning of stochastic resonance for identifying multiple transient faults in rolling element bearings  

NASA Astrophysics Data System (ADS)

Stochastic resonance (SR), a noise-assisted tool, has been proved to be very powerful in weak signal detection. The multiscale noise tuning SR (MSTSR), which breaks the restriction of the requirement of small parameters and white noise in classical SR, has been applied to identify the characteristic frequency of a bearing. However, the multiscale noise tuning (MST), which is originally based on discrete wavelet transform (DWT), limits the signal-to-noise ratio (SNR) improvement of SR and the performance in identifying multiple bearing faults. In this paper, the wavelet packet transform (WPT) is developed and incorporated into the MSTSR method to overcome its shortcomings and to further enhance its capability in multiple faults detection of bearings. The WPT-based MST can achieve a finer tuning of multiscale noise and aims at detecting multiple target frequencies separately. By introducing WPT into the MST of SR, this paper proposes an improved SR method particularly suited for the identification of multiple transient faults in rolling element bearings. Simulated and practical bearing signals carrying multiple characteristic frequencies are employed to validate the performance improvement of the proposed method as compared to the original DWT-based MSTSR method. The results confirm the good capability of the proposed method in multi-fault diagnosis of rolling element bearings.

Wang, Jun; He, Qingbo; Kong, Fanrang

2014-12-01

204

Effect of stochastic resonance whole body vibration on functional performance in the frail elderly: A pilot study.  

PubMed

The aim of this pilot study was to evaluate the feasibility and the effect size of a four-week stochastic resonance whole body vibration (SR-WBV) intervention on functional performance and strength in frail elderly individuals. Twenty-seven participants have been recruited and randomly distributed in an intervention group (IG) and a sham group (SG). Primary outcomes were feasibility objectives like recruitment, compliance and safety. Secondary outcomes were short physical performance battery (SPPB), isometric maximum voluntary contraction (IMVC) and isometric rate of force development (IRFD). The intervention was feasible and safe. Furthermore it showed significant effects (p=0.035) and medium effect size (0.43) within the IG in SPPB. SR-WBV training over four weeks with frail elderly individuals is a safe intervention method. The compliance was good and SR-WBV intervention seems to improve functional performance. Further research over a longer time frame for the strength measurements (IMVC and IRFD) is needed to detect potential intervention effects in the force measurements as well. Clinical Trial register: NTC01704976. PMID:25042993

Kessler, Jessica; Radlinger, Lorenz; Baur, Heiner; Rogan, Slavko

2014-01-01

205

Diagnostic imaging of peripheral vestibular disease in a Chinese goose (Anser cygnoides).  

PubMed

A 20-year-old Chinese goose (Anser cygnoides) presented for severe left-sided head tilt and circling to the left. Peripheral vestibular disease associated with otitis media extending into the left quadrate bone was diagnosed by magnetic resonance imaging and computed tomography. Otoscopy confirmed a ruptured tympanic membrane, and a brainstem auditory evoked response test confirmed loss of hearing in the affected ear. Surgery to remove the caseous material and long-term medical therapy improved the bird's head tilt and quality of life. Otitis, hearing loss, and vestibular disease are rare in birds but can be managed after appropriate investigation. This is the first reported use of multiple advanced diagnostic tests and successful treatment of vestibular disease in a goose. PMID:24881151

Delk, Katie W; Mejia-Fava, Johanna; Jiménez, David A; Kent, Marc; Myrna, Kathern; Mayer, Joerg; Divers, Stephen

2014-03-01

206

Virtual Labyrinth model of vestibular afferent excitation via implanted electrodes – Validation and application to design of a multichannel vestibular prosthesis  

PubMed Central

To facilitate design of a multichannel vestibular prosthesis that can restore sensation to individuals with bilateral loss of vestibular hair cell function, we created a virtual labyrinth model. Model geometry was generated through 3-dimensional (3D) reconstruction of microMRI and microCT scans of normal chinchillas (Chinchilla lanigera) acquired with 30–48 ?m and 12 ?m voxels, respectively. Virtual electrodes were positioned based on anatomic landmarks, and the extracellular potential field during a current pulse was computed using finite element methods. Potential fields then served as inputs to stochastic, nonlinear dynamic models for each of 2415 vestibular afferent axons with spiking dynamics based on a modified Smith and Goldberg model incorporating parameters that varied with fiber location in the neuroepithelium. Action potential propagation was implemented by a well validated model of myelinated fibers. We tested the model by comparing predicted and actual 3D angular vestibulo-ocular reflex (aVOR) axes of eye rotation elicited by prosthetic stimuli. Actual responses were measured using 3D video-oculography. The model was individualized for each animal by placing virtual electrodes based on microCT localization of real electrodes. 3D eye rotation axes were predicted from the relative proportion of model axons excited within each of the three ampullary nerves. Multiple features observed empirically were observed as emergent properties of the model, including effects of active and return electrode position, stimulus amplitude and pulse waveform shape on target fiber recruitment and stimulation selectivity. The modeling procedure is partially automated and can be readily adapted to other species, including humans. PMID:21380738

Hayden, Russell; Sawyer, Stacia; Frey, Eric; Mori, Susumu; Migliaccio, Americo A.; Della Santina, Charles C.

2012-01-01

207

[Should vestibular neuritis be treated with corticosteroids?].  

PubMed

Recent studies have shown that corticosteroid treatment of patients with vestibular neuritis significantly improves recovery of peripheral vestibular function. At follow-up, the number of patients with a normal caloric response was larger among those treated with corticosteroids. However, improvement of caloric responses may not correlate directly with patient symptoms and up to now improved vertigo/dizziness due to corticosteroid treatment has not been reported. Consequently, although corticosteroid may be a treatment option, it should currently only be considered in those vestibular neuritis patients who are willing to take part in a structured follow-up with both caloric testing and evaluation of subjective symptoms. PMID:18846122

Brantberg, Krister; Goplen, Frederik; Brĺthen, Geir; Nordahl, Stein Helge Glad; Arnesen, Haakon

2008-09-25

208

Enlarged Vestibular Aqueducts and Childhood Hearing Loss  

MedlinePLUS

... These organs are the cochlea, which detects sound waves and turns them into nerve signals, and the vestibular labyrinth, which detects movement and gravity. These organs, together with the nerves that send ...

209

Calcified vestibular schwannoma in the cerebellopontine angle.  

PubMed

Although vestibular schwannoma is a common tumor in the cerebellopontine angle, calcified vestibular schwannoma is rare. A 59-year-old woman with sudden onset epileptic seizures, was referred to Hokkaido Neurosurgical Memorial Hospital. Neurological examination revealed left Bruns nystagmus, left deafness and left cerebellar ataxia. Brain MRI revealed a mass, about 3cm in diameter, in the left cerebellopontine angle. The mass showed heterogeneous intensity on T1- and T2-weighted and fluid-attenuated inversion recovery (FLAIR) images. Hydrocephalus was seen. On CT scan, the tumor was calcified. Preoperatively, vestibular schwannoma, meningioma, cavernous hemangioma, or thrombosed giant aneurysm were considered as differential diagnoses. The pathological diagnosis was schwannoma. For a calcified mass in the cerebellopontine angle, vestibular schwannoma should be considered in the differential diagnosis to plan appropriate treatment strategies. PMID:17884507

Katoh, Masahito; Aida, Toshimitsu; Imamura, Hiroyuki; Aoki, Takeshi; Yoshino, Masami; Kashiwazaki, Daina; Takei, Hidetoshi

2007-12-01

210

The altered vestibular-evoked myogenic and whole-body postural responses in old men during standing.  

PubMed

Age-related decrements within the sensorimotor system may lead to alterations and impairments in postural control, but a link to a vestibular mechanism is unclear. The purpose of the present study was to determine whether vestibular control of standing balance is altered with adult aging. Eight old (~77years) and eight young (~26years) men stood without aids on a commercially available force plate with their head turned to the right, arms relaxed at their sides and eyes closed while receiving stochastic vestibular stimuli (0-25Hz, root mean square amplitude=0.85mA). Surface electromyography signals were sampled from the left soleus, medial gastrocnemius and tibialis anterior. Whole-body balance, as measured by the anteroposterior forces and muscle responses, was quantified using frequency (coherence and gain functions) and time (cumulant density function) domain correlations with the vestibular stimuli. Old men exhibited a compressed frequency response of the vestibular reflex with a greater relative gain at lower frequencies for the plantar flexors and anteroposterior forces than young. In the time domain, the peak amplitude of the short latency response was 45-64% lower for the plantar flexors and anteroposterior forces (p?0.05) in the old than young, but not for the tibialis anterior (p=0.21). The old men had a 190% and 31% larger medium latency response for only the tibialis anterior and anteroposterior forces, respectively, than young (p?0.01). A strong correlation between the tibialis anterior and the force response was also detected (r=0.80, p<0.01). In conclusion, net vestibular-evoked muscle responses led to smaller short and larger medium latency peak amplitudes in anteroposterior forces for the old. The present results likely resulted from a compressed and lower operational frequency range of the vestibular reflexes and the activation of additional muscles (tibialis anterior) to maintain standing balance. PMID:25456846

Dalton, Brian H; Blouin, Jean-Sébastien; Allen, Matti D; Rice, Charles L; Inglis, J Timothy

2014-12-01

211

Basic Concepts in Understanding Recovery of Function in Vestibular Reflex Networks during Vestibular Compensation  

PubMed Central

Unilateral peripheral vestibular lesions produce a syndrome of oculomotor and postural deficits with the symptoms at rest, the static symptoms, partially or completely normalizing shortly after the lesion due to a process known as vestibular compensation. The symptoms are thought to result from changes in the activity of vestibular sensorimotor reflexes. Since the vestibular nuclei must be intact for recovery to occur, many investigations have focused on studying these neurons after lesions. At present, the neuronal plasticity underlying early recovery from the static symptoms is not fully understood. Here we propose that knowledge of the reflex identity and input–output connections of the recorded neurons is essential to link the responses to animal behavior. We further propose that the cellular mechanisms underlying vestibular compensation can be sorted out by characterizing the synaptic responses and time course for change in morphologically defined subsets of vestibular reflex projection neurons. Accordingly, this review focuses on the perspective gained by performing electrophysiological and immunolabeling studies on a specific subset of morphologically defined, glutamatergic vestibular reflex projection neurons, the principal cells of the chick tangential nucleus. Reference is made to pertinent findings from other studies on vestibular nuclei neurons, but no comprehensive review of the literature is intended since broad reviews already exist. From recording excitatory and inhibitory spontaneous synaptic activity in principal cells, we find that the rebalancing of excitatory synaptic drive bilaterally is essential for vestibular compensation to proceed. This work is important for it defines for the first time the excitatory and inhibitory nature of the changing synaptic inputs and the time course for changes in a morphologically defined subset of vestibular reflex projection neurons during early stages of vestibular compensation. PMID:22363316

Peusner, Kenna D.; Shao, Mei; Reddaway, Rebecca; Hirsch, June C.

2012-01-01

212

Vestibular development in marsupials and monotremes.  

PubMed

The young of marsupials and monotremes are all born in an immature state, followed by prolonged nurturing by maternal lactation in either a pouch or nest. Nevertheless, the level of locomotor ability required for newborn marsupials and monotremes to reach the safety of the pouch or nest varies considerably: some are transferred to the pouch or nest in an egg (monotremes); others are transferred passively by gravity (e.g. dasyurid marsupials); some have only a horizontal wriggle to make (e.g. peramelid and didelphid marsupials); and others must climb vertically for a long distance to reach the maternal pouch (e.g. diprotodontid marsupials). In the present study, archived sections of the inner ear and hindbrain held in the Bolk, Hill and Hubrecht collections at the Museum für Naturkunde, Berlin, were used to test the relationship between structural maturity of the vestibular apparatus and the locomotor challenges that face the young of these different mammalian groups. A system for staging different levels of structural maturity of the vestibular apparatus was applied to the embryos, pouch young and hatchlings, and correlated with somatic size as indicated by greatest body length. Dasyurids are born at the most immature state, with the vestibular apparatus at little more than the otocyst stage. Peramelids are born with the vestibular apparatus at a more mature state (fully developed semicircular ducts and a ductus reuniens forming between the cochlear duct and saccule, but no semicircular canals). Diprotodontids and monotremes are born with the vestibular apparatus at the most mature state for the non-eutherians (semicircular canals formed, maculae present, but vestibular nuclei in the brainstem not yet differentiated). Monotremes and marsupials reach the later stages of vestibular apparatus development at mean body lengths that lie within the range of those found for laboratory rodents (mouse and rat) reaching the same vestibular stage. PMID:24298911

Ashwell, Ken W S; Shulruf, Boaz

2014-04-01

213

Vestibular-visual interactions in flight simulators  

NASA Technical Reports Server (NTRS)

All 139 research papers published under this ten-year program are listed. Experimental work was carried out at the Ames Research Center involving man's sensitivity to rotational acceleration, and psychophysical functioning of the semicircular canals; vestibular-visual interactions and effects of other sensory systems were studied in flight simulator environments. Experiments also dealt with the neurophysiological vestibular functions of animals, and flight management investigations of man-vehicle interactions.

Clark, B.

1977-01-01

214

Vestibular disorders in migrainous children and adolescents  

Microsoft Academic Search

Recurrent vertigo is a special form of migraine in childhood. It is a periodic syndrome of childhood which was previously\\u000a called migraine equivalent. Thirty young patients (less than 18 years of age) with migraine and vertigo were examined by the\\u000a authors. The vestibular system of the patients was examined by computer-based electronystagmography. All patients had migraine-related\\u000a vestibular dysfunction. Most had

Ágnes Szirmai; Viktor Farkas

2000-01-01

215

Unilateral Vestibular Loss Impairs External Space Representation  

PubMed Central

The vestibular system is responsible for a wide range of postural and oculomotor functions and maintains an internal, updated representation of the position and movement of the head in space. In this study, we assessed whether unilateral vestibular loss affects external space representation. Patients with Meničre's disease and healthy participants were instructed to point to memorized targets in near (peripersonal) and far (extrapersonal) spaces in the absence or presence of a visual background. These individuals were also required to estimate their body pointing direction. Meničre's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (one week and one month after the operation), and healthy participants were tested at similar times. Unilateral vestibular loss impaired the representation of both the external space and the body pointing direction: in the dark, the configuration of perceived targets was shifted toward the lesioned side and compressed toward the contralesioned hemifield, with higher pointing error in the near space. Performance varied according to the time elapsed after neurotomy: deficits were stronger during the early stages, while gradual compensation occurred subsequently. These findings provide the first demonstration of the critical role of vestibular signals in the representation of external space and of body pointing direction in the early stages after unilateral vestibular loss. PMID:24523916

Borel, Liliane; Redon-Zouiteni, Christine; Cauvin, Pierre; Dumitrescu, Michel; Devčze, Arnaud; Magnan, Jacques; Péruch, Patrick

2014-01-01

216

Vestibular ontogeny: Measuring the influence of the dynamic environment  

NASA Technical Reports Server (NTRS)

In comparison to other special senses, we are only meagerly informed about the development of vestibular function and the mechanisms that may operate to control or influence the course of vestibular ontogeny. Perhaps one contributing factor to this disparity is the difficulty of evaluating vestibular sense organs directly and noninvasively. The present report describes a recently developed direct noninvasive vestibular function test that can be used to address many basic questions about the developing vestibular system. More particularly, the test can be used to examine the effects of the dynamic environment (e.g. gravitational field and vibration) on vestibular ontogeny.

Jones, Timothy A.; Devries, Sherri M.; Dubois, Linda M.; Nelson, Rick C.

1993-01-01

217

Enhanced balance associated with coordination training with stochastic resonance stimulation in subjects with functional ankle instability: an experimental trial  

PubMed Central

Background Ankle sprains are common injuries that often lead to functional ankle instability (FAI), which is a pathology defined by sensations of instability at the ankle and recurrent ankle sprain injury. Poor postural stability has been associated with FAI, and sports medicine clinicians rehabilitate balance deficits to prevent ankle sprains. Subsensory electrical noise known as stochastic resonance (SR) stimulation has been used in conjunction with coordination training to improve dynamic postural instabilities associated with FAI. However, unlike static postural deficits, dynamic impairments have not been indicative of ankle sprain injury. Therefore, the purpose of this study was to examine the effects of coordination training with or without SR stimulation on static postural stability. Improving postural instabilities associated with FAI has implications for increasing ankle joint stability and decreasing recurrent ankle sprains. Methods This study was conducted in a research laboratory. Thirty subjects with FAI were randomly assigned to either a: 1) conventional coordination training group (CCT); 2) SR stimulation coordination training group (SCT); or 3) control group. Training groups performed coordination exercises for six weeks. The SCT group received SR stimulation during training, while the CCT group only performed coordination training. Single leg postural stability was measured after the completion of balance training. Static postural stability was quantified on a force plate using anterior/posterior (A/P) and medial/lateral (M/L) center-of-pressure velocity (COPvel), M/L COP standard deviation (COPsd), M/L COP maximum excursion (COPmax), and COP area (COParea). Results Treatment effects comparing posttest to pretest COP measures were highest for the SCT group. At posttest, the SCT group had reduced A/P COPvel (2.3 ± 0.4 cm/s vs. 2.7 ± 0.6 cm/s), M/L COPvel (2.6 ± 0.5 cm/s vs. 2.9 ± 0.5 cm/s), M/L COPsd (0.63 ± 0.12 cm vs. 0.73 ± 0.11 cm), M/L COPmax (1.76 ± 0.25 cm vs. 1.98 ± 0.25 cm), and COParea (0.13 ± 0.03 cm2 vs. 0.16 ± 0.04 cm2) than the pooled means of the CCT and control groups (P < 0.05). Conclusion Reduced values in COP measures indicated postural stability improvements. Thus, six weeks of coordination training with SR stimulation enhanced postural stability. Future research should examine the use of SR stimulation for decreasing recurrent ankle sprain injury in physically active individuals with FAI. PMID:18086314

Ross, Scott E; Arnold, Brent L; Blackburn, J Troy; Brown, Cathleen N; Guskiewicz, Kevin M

2007-01-01

218

Pharmacotherapy of vestibular disorders and nystagmus.  

PubMed

Vertigo and dizziness are with a life-time prevalence of ~30% among the most common symptoms and are often associated with nystagmus or other oculomotor disorders. The prerequisite for a successful treatment is a precise diagnosis of the underlying disorder. In this overview, the current pharmacological treatment options for peripheral and central vestibular, cerebellar, and oculomotor disorders including nystagmus are described. There are basically seven groups of drugs that can be used (the "7 As"): antiemetics; anti-inflammatory, anti-Meničre's, and antimigraine medications; antidepressants, anticonvulsants, and aminopyridines. In acute vestibular neuritis, recovery of the peripheral vestibular function can be improved by treatment with oral corticosteroids. In Meničre's disease, a long-term high-dose treatment with betahistine-dihydrochloride (at least 48 mg three times daily) had a significant effect on the frequency of the attacks; the underlying mode of action is evidently an increase in inner-ear blood flow. The use of aminopyridines is a well-established therapeutic principle in the treatment of downbeat and upbeat nystagmus as well as episodic ataxia type 2 and cerebellar gait disorders. As was shown in animal experiments, these potassium channel blockers increase the activity and excitability and normalize irregular firing of cerebellar Purkinje cells. They evidently augment the inhibitory influence of these cells on vestibular and deep cerebellar nuclei. A few studies showed that baclofen improves periodic alternating nystagmus; gabapentin and memantine improve pendular and infantile nystagmus. However, many other eye-movement disorders such as ocular flutter, opsoclonus, central positioning, and see-saw nystagmus are still difficult to treat. Although substantial progress has been made, further state-of-the-art trials must still be performed on many vestibular and oculomotor disorders, namely Meničre's disease, vestibular paroxysmia, vestibular migraine, and many forms of central eye-movement disorders. PMID:24057832

Strupp, Michael; Kremmyda, Olympia; Brandt, Thomas

2013-07-01

219

Neurotology symptoms at referral to vestibular evaluation  

PubMed Central

Background Dizziness-vertigo is common in adults, but clinical providers may rarely diagnose vestibular impairment and referral could be delayed. To assess neurotology symptoms (including triggers) reported by patients with peripheral vestibular disease, during the year just before their referral to vestibular evaluation. Methods 282 patients with peripheral vestibular disease and 282 control subjects accepted to participate. They had no middle ear, retinal, neurological, psychiatric, autoimmune or autonomic disorders. They reported their symptoms by a standardized questionnaire along with their anxiety/depression symptoms. Results Patients were referred after months or years from the onset of their symptoms, 24% of them reported frequent falls with a long clinical evolution; 10% of them reported no vertigo but instability related to specific triggers; 86% patients and 12% control subjects reported instability when moving the head rapidly and 79% patients and 6% control subjects reported instability when changing posture. Seven out of the 9 symptoms explored by the questionnaire allowed the correct classification of circa 95% of the participants (Discriminant function analysis, p?vestibular evaluation may underlie a history of frequent falls; some patients may not report vertigo, but instability related to specific triggers, which could be useful to prompt vestibular evaluation. High blood pressure, dyslipidemia and anxiety/depression symptoms may have a mild influence on the report of symptoms of vestibular disease in both, patients and control subjects. PMID:24279682

2013-01-01

220

Auditory and Vestibular Issues Related to Human Spaceflight  

NASA Technical Reports Server (NTRS)

Human spaceflight provides unique opportunities to study human vestibular and auditory systems. This session will discuss 1) vestibular adaptive processes reflected by pronounced perceptual and motor coordination problems during, and after, space missions; 2) vestibular diagnostic and rehabilitative techniques (used to promote recovery after living in altered gravity environments) that may be relevant to treatment of vestibular disorders on earth; and 3) unique acoustical challenges to hearing loss prevention and crew performance during spaceflight missions.

Danielson, Richard W.; Wood, Scott J.

2009-01-01

221

Large Vestibular Schwannomas Presenting during Pregnancy: Management Strategies.  

PubMed

Objective?Large vestibular schwannomas rarely present in pregnant women. Diagnosis and management of these tumors during pregnancy present a therapeutic challenge. Methods?A 20-year-old primigravida woman at 26 weeks' gestation was transferred to our facility with gait imbalance, left facial weakness, left ear hearing loss, and recent nausea and vomiting. Magnetic resonance imaging revealed a large left cerebellopontine angle mass with extension into the left internal auditory canal and compression of the fourth ventricle resulting in mild hydrocephalus. The patient was admitted with a plan for early delivery at 32 weeks followed by tumor resection. One week later, the patient's headache and neurologic symptoms worsened due to increased hydrocephalus; a ventriculoperitoneal shunt was placed. The next day, an emergent cesarean delivery was performed due to worsening respiratory status. Four days later, a tracheostomy and percutaneous endoscopic gastrostomy tube were placed due to dysphagia. Eight days after the delivery, the mass was resected with a left retrosigmoid approach without complications. Immunohistochemistry confirmed vestibular cellular schwannoma on cranial nerve VIII showing unusually high mitotic activity. Results?The patient was discharged to inpatient rehabilitation on postoperative day 12 without new neurologic deficit. At 1?month, the patient was swallowing without aspiration. Her facial sensation had returned, her facial weakness remained stable, and her gait was significantly improved. Conclusion?If the patient is neurologically stable, the best option is to delay resection until after delivery. If resection is necessary during pregnancy, the optimal time is during the second trimester. PMID:25072015

Shah, Kushal J; Chamoun, Roukoz B

2014-06-01

222

[The research progress of large vestibular aqueduct syndrome].  

PubMed

Large vestibular aqueduct syndrome (LVAS) is one of common non-syndromic hearing disorders. With the rapid development of medical imaging, audiology, molecular biology, genetics, cochlear implant surgery, we have made remarkable achievements in the diagnosis and treatment of large vestibular aqueduct syndrome. This article reviewed related researches of the large vestibular aqueduct syndrome. PMID:23379123

Abulikemu, Yiming; Tang, Liang; Zhang, Jin

2012-11-01

223

Evidence for reflex and perceptual vestibular contributions to postural control  

Microsoft Academic Search

Vestibular signals are known to have an important role in stance under specific conditions. Potentially these effects could be modulated by vestibular reflexes or by voluntary responses to perceived vestibular signals. Our preliminary aim was to confirm that vestibulospinal reflexes change in parallel with sway under different postural conditions, and then to determine whether any relationship was present between these

Ann M. Bacsi; James G. Colebatch

2005-01-01

224

Sensorial countermeasures for vestibular spatial disorientation.  

PubMed

Spatial disorientation is defined as an erroneous body orientation perceived by pilots during flights. Limits of the vestibular system provoke frequent spatial disorientation mishaps. Although vestibular spatial disorientation is experienced frequently in aviation, there is no intuitive countermeasure against spatial disorientation mishaps to date. The aim of this review is to describe the current sensorial countermeasures and to examine future leads in sensorial ergonomics for vestibular spatial disorientation. This work reviews: 1) the visual ergonomics, 2) the vestibular countermeasures, 3) the auditory displays, 4) the somatosensory countermeasures, and, finally, 5) the multisensory displays. This review emphasizes the positive aspects of auditory and somatosensory countermeasures as well as multisensory devices. Even if some aspects such as sensory conflict and motion sickness need to be assessed, these countermeasures should be taken into consideration for ergonomics work in the future. However, a recent development in aviation might offer new and better perspectives: unmanned aerial vehicles. Unmanned aerial vehicles aim to go beyond the physiological boundaries of human sensorial systems and would allow for coping with spatial disorientation and motion sickness. Even if research is necessary to improve the interaction between machines and humans, this recent development might be incredibly useful for decreasing or even stopping vestibular spatial disorientation. PMID:24834571

Paillard, Aurore C; Quarck, Gaëlle; Denise, Pierre

2014-05-01

225

Complications of Microsurgery of Vestibular Schwannoma  

PubMed Central

Background. The aim of this study was to analyze complications of vestibular schwannoma (VS) microsurgery. Material and Methods. A retrospective study was performed in 333 patients with unilateral vestibular schwannoma indicated for surgical treatment between January 1997 and December 2012. Postoperative complications were assessed immediately after VS surgery as well as during outpatient followup. Results. In all 333 patients microsurgical vestibular schwannoma (Koos grade 1: 12, grade 2: 34, grade 3: 62, and grade 4: 225) removal was performed. The main neurological complication was facial nerve dysfunction. The intermediate and poor function (HB III–VI) was observed in 124 cases (45%) immediately after surgery and in 104 cases (33%) on the last followup. We encountered disordered vestibular compensation in 13%, permanent trigeminal nerve dysfunction in 1%, and transient lower cranial nerves (IX–XI) deficit in 6%. Nonneurological complications included CSF leakage in 63% (lateral/medial variant: 99/1%), headache in 9%, and intracerebral hemorrhage in 5%. We did not encounter any case of meningitis. Conclusions. Our study demonstrates that despite the benefits of advanced high-tech equipment, refined microsurgical instruments, and highly developed neuroimaging technologies, there are still various and significant complications associated with vestibular schwannomas microsurgery. PMID:24987677

Zv??ina, Eduard; Balogová, Zuzana; Sk?ivan, Ji?í; Kraus, Josef; Syka, Josef; Chovanec, Martin

2014-01-01

226

Visual Dependency and Dizziness after Vestibular Neuritis  

PubMed Central

Symptomatic recovery after acute vestibular neuritis (VN) is variable, with around 50% of patients reporting long term vestibular symptoms; hence, it is essential to identify factors related to poor clinical outcome. Here we investigated whether excessive reliance on visual input for spatial orientation (visual dependence) was associated with long term vestibular symptoms following acute VN. Twenty-eight patients with VN and 25 normal control subjects were included. Patients were enrolled at least 6 months after acute illness. Recovery status was not a criterion for study entry, allowing recruitment of patients with a full range of persistent symptoms. We measured visual dependence with a laptop-based Rod-and-Disk Test and severity of symptoms with the Dizziness Handicap Inventory (DHI). The third of patients showing the worst clinical outcomes (mean DHI score 36–80) had significantly greater visual dependence than normal subjects (6.35° error vs. 3.39° respectively, p?=?0.03). Asymptomatic patients and those with minor residual symptoms did not differ from controls. Visual dependence was associated with high levels of persistent vestibular symptoms after acute VN. Over-reliance on visual information for spatial orientation is one characteristic of poorly recovered vestibular neuritis patients. The finding may be clinically useful given that visual dependence may be modified through rehabilitation desensitization techniques. PMID:25233234

Cousins, Sian; Cutfield, Nicholas J.; Kaski, Diego; Palla, Antonella; Seemungal, Barry M.; Golding, John F.; Staab, Jeffrey P.; Bronstein, Adolfo M.

2014-01-01

227

Neural Correlates of Sensory Substitution in Vestibular Pathways Following Complete Vestibular Loss  

PubMed Central

Sensory substitution is the term typically used in reference to sensory prosthetic devices designed to replace input from one defective modality with input from another modality. Such devices allow an alternative encoding of sensory information that is no longer directly provided by the defective modality in a purposeful and goal-directed manner. The behavioral recovery that follows complete vestibular loss is impressive and has long been thought to take advantage of a natural form of sensory substitution in which head motion information is no longer provided by vestibular inputs, but instead by extra-vestibular inputs such as proprioceptive and motor efference copy signals. Here we examined the neuronal correlates of this behavioral recovery after complete vestibular loss in alert behaving monkeys (Macaca mulata). We show for the first time that extra-vestibular inputs substitute for the vestibular inputs to stabilize gaze at the level of single neurons in the VOR premotor circuitry. The summed weighting of neck proprioceptive and efference copy information was sufficient to explain simultaneously observed behavioral improvements in gaze stability. Furthermore, by altering correspondence between intended and actual head movement we revealed a four-fold increase in the weight of neck motor efference copy signals consistent with the enhanced behavioral recovery observed when head movements are voluntary versus unexpected. Thus, taken together our results provide direct evidence that the substitution by extra-vestibular inputs in vestibular pathways provides a neural correlate for the improvements in gaze stability that are observed following the total loss of vestibular inputs. PMID:23077054

Sadeghi, Soroush G.; Minor, Lloyd B.; Cullen, Kathleen E.

2012-01-01

228

Optical nerve stimulation for a vestibular prosthesis  

NASA Astrophysics Data System (ADS)

Infrared Nerve Stimulation (INS) offers several advantages over electrical stimulation, including more precise spatial selectivity and improved surgical access. In this study, INS and electrical stimulation were compared in their ability to activate the vestibular branch of the VIIIth nerve, as a potential way to treat balance disorders. The superior and lateral canals of the vestibular system of Guinea pigs were identified and approached with the aid of precise 3-D reconstructions. A monopolar platinum stimulating electrode was positioned near the ampullae of the canals, and biphasic current pulses were used to stimulate vestibular evoked potentials and eye movements. Thresholds and input/output functions were measured for various stimulus conditions. A short pulsed diode laser (Capella, Lockheed Martin-Aculight, Inc., Bothell WA) was placed in the same anatomical position and various stimulus conditions were evaluated in their ability to evoke similar potentials and eye movements.

Harris, David M.; Bierer, Steven M.; Wells, Jonathon D.; Phillips, James O.

2009-02-01

229

Vestibular function in HIV patients: preliminary report  

PubMed Central

Summary Main purpose of this study was to evaluate vestibular function, focusing attention on percentage of peripheral damage in 30 HIV positive patients (23 male, 7 female), age range 26-68 years, belonging to Categories A-C of CDC classification of infection, underwent electronystagmography with bithermic stimulation according to Freyss (125 cc of water at 30 °C and 44 °C in 30 sec). The angular velocity of slow phase was considered as the main value of labirinthine functionality. Peripheral vestibular damage has been found in 35.7% of Class A patients; a similar percentage of peripheral signs was found in Classes B and C, where, on the contrary, increased central vestibular signs were observed. In order to evaluate equilibrium in these patients, a Dynamic Gait Index (DGI) test was performed. Scores were > 21 points in 85.7% of Class A patients and decreased in Classes B and C. PMID:17063983

Teggi, R; Giordano, L; Pistorio, V; Bussi, M

2006-01-01

230

Resonance  

NSDL National Science Digital Library

For advanced undergraduate students: Observe resonance in a collection of driven, damped harmonic oscillators. Vary the driving frequency and amplitude, the damping constant, and the mass and spring constant of each resonator. Notice the long-lived transients when damping is small, and observe the phase change for resonators above and below resonance.

Simulations, Phet I.; Dubson, Michael; Loeblein, Patricia; Olson, Jonathan; Perkins, Kathy; Gratny, Mindy

2011-07-20

231

A systems concept of the vestibular organs  

NASA Technical Reports Server (NTRS)

A comprehensive model of vestibular organ function is presented. The model is based on an analogy with the inertial guidance systems used in navigation. Three distinct operations are investigated: angular motion sensing, linear motion sensing, and computation. These operations correspond to the semicircular canals, the otoliths, and central processing respectively. It is especially important for both an inertial guidance system and the vestibular organs to distinguish between attitude with respect to the vertical on the one hand, and linear velocity and displacement on the other. The model is applied to various experimental situations and found to be corroborated by them.

Mayne, R.

1974-01-01

232

Calcification of vestibular schwannoma: a case report and literature review  

PubMed Central

Calcification rarely occurs in vestibular schwannoma (VS), and only seven cases of calcified VS have been reported in the literature. Here, we report a 48-year-old man with VS, who had a history of progressive left-sided hearing loss for 3 years. Neurological examination revealed that he had left-sided hearing loss and left cerebellar ataxia. Magnetic resonance imaging and computerized tomography angiography showed a mass with calcification in the left cerebellopontine angle (CPA). The tumor was successfully removed via suboccipital craniotomy, and postoperative histopathology showed that the tumor was a schwannoma. We reviewed seven cases of calcified VS that were previously reported in the literature, and we analyzed and summarized the characteristics of these tumors, including the calcification, texture, and blood supply. We conclude that calcification in VS is associated with its texture and blood supply, and these characteristics affect the surgical removal of the tumor. PMID:23031739

2012-01-01

233

Current treatment of vestibular, ocular motor disorders and nystagmus.  

PubMed

Vertigo and dizziness are among the most common complaints with a lifetime prevalence of about 30%. The various forms of vestibular disorders can be treated with pharmacological therapy, physical therapy, psychotherapeutic measures or, rarely, surgery. In this review, the current pharmacological treatment options for peripheral and central vestibular, cerebellar and ocular motor disorders will be described. They are as follows for peripheral vestibular disorders. In vestibular neuritis recovery of the peripheral vestibular function can be improved by treatment with oral corticosteroids. In Meničre's disease a recent study showed long-term high-dose treatment with betahistine has a significant effect on the frequency of the attacks. The use of aminopyridines introduced a new therapeutic principle in the treatment of downbeat and upbeat nystagmus and episodic ataxia type 2 (EA 2). These potassium channel blockers presumably increase the activity and excitability of cerebellar Purkinje cells, thereby augmenting the inhibitory influence of these cells on vestibular and cerebellar nuclei. A few studies showed that baclofen improves periodic alternating nystagmus, and gabapentin and memantine, pendular nystagmus. However, many other eye movement disorders such as ocular flutter opsoclonus, central positioning, or see-saw nystagmus are still difficult to treat. Although progress has been made in the treatment of vestibular neuritis, downbeat and upbeat nystagmus, as well as EA 2, state-of-the-art trials must still be performed on many vestibular and ocular motor disorders, namely Meničre's disease, bilateral vestibular failure, vestibular paroxysmia, vestibular migraine, and many forms of central eye movement disorders. PMID:21179531

Strupp, Michael; Brandt, Thomas

2009-07-01

234

Ocular vestibular evoked myogenic potentials in patients with acoustic neuroma.  

PubMed

To assess the usefulness of vestibular testing in patients with acoustic neuroma, considering two main aspects: to compare diagnostic sensitivity of the current vestibular tests, especially considering ocular vestibular evoked myogenic potentials (OVEMPs) and to identify pre-operative localization of the tumor (inferior vestibular nerve vs. superior vestibular nerve) only with the help of vestibular electrophysiological data. Twenty-six patients with unilateral acoustic neuroma (mainly intracanalicular type) were studied with a full audio-vestibular test battery (pure tone and speech audiometry, caloric bithermal test, vibration-induced nystagmus test (VIN), cervical and OVEMPs). 18 patients (69 %) showed abnormal caloric responses. 12 patients (46.2 %) showed a pattern of VIN test suggestive of vestibular asymmetry. 16 patients (61.5 %) showed abnormal OVEMPs (12 only to AC, 4 both to AC and BC). 10 patients (38.5 %) showed abnormal cervical vestibular evoked myogenic potentials (5 both to AC and BC, 5 only to AC). In one case, results of vestibular evoked potentials and caloric test were confirmed by intra-operative and post-operative findings. Results of electrophysiological tests in AN patients could be helpful for planning the proper surgical approach, considering that sensitivity of every exam is quite low in intracanalicular lesion; clinical data allow a better interpretation of vestibular evoked myogenic potentials. PMID:22526579

Piras, Gianluca; Brandolini, Cristina; Castellucci, Andrea; Modugno, Giovanni Carlo

2013-02-01

235

Interactions between Stress and Vestibular Compensation – A Review  

PubMed Central

Elevated levels of stress and anxiety often accompany vestibular dysfunction, while conversely complaints of dizziness and loss of balance are common in patients with panic and other anxiety disorders. The interactions between stress and vestibular function have been investigated both in animal models and in clinical studies. Evidence from animal studies indicates that vestibular symptoms are effective in activating the stress axis, and that the acute stress response is important in promoting compensatory synaptic and neuronal plasticity in the vestibular system and cerebellum. The role of stress in human vestibular disorders is complex, and definitive evidence is lacking. This article reviews the evidence from animal and clinical studies with a focus on the effects of stress on the central vestibular pathways and their role in the pathogenesis and management of human vestibular disorders. PMID:22866048

Saman, Yougan; Bamiou, D. E.; Gleeson, Michael; Dutia, Mayank B.

2012-01-01

236

From ear to uncertainty: vestibular contributions to cognitive function  

PubMed Central

In addition to the deficits in the vestibulo-ocular and vestibulo-spinal reflexes that occur following vestibular dysfunction, there is substantial evidence that vestibular loss also causes cognitive disorders, some of which may be due to the reflexive deficits and some of which are related to the role that ascending vestibular pathways to the limbic system and neocortex play in spatial orientation. In this review we summarize the evidence that vestibular loss causes cognitive disorders, especially spatial memory deficits, in animals and humans and critically evaluate the evidence that these deficits are not due to hearing loss, problems with motor control, oscillopsia or anxiety and depression. We review the evidence that vestibular lesions affect head direction and place cells as well as the emerging evidence that artificial activation of the vestibular system, using galvanic vestibular stimulation (GVS), can modulate cognitive function. PMID:24324413

Smith, Paul F.; Zheng, Yiwen

2013-01-01

237

Vestibular convergence patterns in vestibular nuclei neurons of alert primates  

NASA Technical Reports Server (NTRS)

Sensory signal convergence is a fundamental and important aspect of brain function. Such convergence may often involve complex multidimensional interactions as those proposed for the processing of otolith and semicircular canal (SCC) information for the detection of translational head movements and the effective discrimination from physically congruent gravity signals. In the present study, we have examined the responses of primate rostral vestibular nuclei (VN) neurons that do not exhibit any eye movement-related activity using 0.5-Hz translational and three-dimensional (3D) rotational motion. Three distinct neural populations were identified. Approximately one-fourth of the cells exclusively encoded rotational movements (canal-only neurons) and were unresponsive to translation. The canal-only central neurons encoded head rotation in SCC coordinates, exhibited little orthogonal canal convergence, and were characterized with significantly higher sensitivities to rotation as compared to primary SCC afferents. Another fourth of the neurons modulated their firing rates during translation (otolith-only cells). During rotations, these neurons only responded when the axis of rotation was earth-horizontal and the head was changing orientation relative to gravity. The remaining one-half of VN neurons were sensitive to both rotations and translations (otolith + canal neurons). Unlike primary otolith afferents, however, central neurons often exhibited significant spatiotemporal (noncosine) tuning properties and a wide variety of response dynamics to translation. To characterize the pattern of SCC inputs to otolith + canal neurons, their rotational maximum sensitivity vectors were computed using exclusively responses during earth-vertical axis rotations (EVA). Maximum sensitivity vectors were distributed throughout the 3D space, suggesting strong convergence from multiple SCCs. These neurons were also tested with earth-horizontal axis rotations (EHA), which would activate both vertical canals and otolith organs. However, the recorded responses could not be predicted from a linear combination of EVA rotational and translational responses. In contrast, one-third of the neurons responded similarly during EVA and EHA rotations, although a significant response modulation was present during translation. Thus this subpopulation of otolith + canal cells, which included neurons with either high- or low-pass dynamics to translation, appear to selectively ignore the component of otolith-selective activation that is due to changes in the orientation of the head relative to gravity. Thus contrary to primary otolith afferents and otolith-only central neurons that respond equivalently to tilts relative to gravity and translational movements, approximately one-third of the otolith + canal cells seem to encode a true estimate of the translational component of the imposed passive head and body movement.

Dickman, J. David; Angelaki, Dora E.

2002-01-01

238

Vestibular Cues and Virtual Environments: Choosing the Magnitude of the Vestibular Cue  

Microsoft Academic Search

The design of virtual environments usually concentrateson constructing a realistic visual simulation andignores the non-visual cues normally associated withmoving through an environment. The lack of the normalcomplement of cues may contribute to cybersicknessand may a#ect operator performance. In #5# wedescribed the e#ect of adding vestibular cues duringpassive linear motion and showed an unexpected dominanceof the vestibular cue in determining the

Laurence R. Harris; Michael Jenkin; Daniel C. Zikovitz

1999-01-01

239

Interaction between Vestibular Compensation Mechanisms and Vestibular Rehabilitation Therapy: 10 Recommendations for Optimal Functional Recovery  

PubMed Central

This review questions the relationships between the plastic events responsible for the recovery of vestibular function after a unilateral vestibular loss (vestibular compensation), which has been well described in animal models in the last decades, and the vestibular rehabilitation (VR) therapy elaborated on a more empirical basis for vestibular loss patients. The main objective is not to propose a catalog of results but to provide clinicians with an understandable view on when and how to perform VR therapy, and why VR may benefit from basic knowledge and may influence the recovery process. With this perspective, 10 major recommendations are proposed as ways to identify an optimal functional recovery. Among them are the crucial role of active and early VR therapy, coincidental with a post-lesion sensitive period for neuronal network remodeling, the instructive role that VR therapy may play in this functional reorganization, the need for progression in the VR therapy protocol, which is based mainly on adaptation processes, the necessity to take into account the sensorimotor, cognitive, and emotional profile of the patient to propose individual or “ŕ la carte” VR therapies, and the importance of motivational and ecologic contexts. More than 10 general principles are very likely, but these principles seem crucial for the fast recovery of vestibular loss patients to ensure good quality of life. PMID:25610424

Lacour, Michel; Bernard-Demanze, Laurence

2015-01-01

240

Vestibular stimulation leads to distinct hemodynamic patterning  

NASA Technical Reports Server (NTRS)

Previous studies demonstrated that responses of a particular sympathetic nerve to vestibular stimulation depend on the type of tissue the nerve innervates as well as its anatomic location. In the present study, we sought to determine whether such precise patterning of vestibulosympathetic reflexes could lead to specific hemodynamic alterations in response to vestibular afferent activation. We simultaneously measured changes in systemic blood pressure and blood flow (with the use of Doppler flowmetry) to the hindlimb (femoral artery), forelimb (brachial artery), and kidney (renal artery) in chloralose-urethane-anesthetized, baroreceptor-denervated cats. Electrical vestibular stimulation led to depressor responses, 8 +/- 2 mmHg (mean +/- SE) in magnitude, that were accompanied by decreases in femoral vasoconstriction (23 +/- 4% decrease in vascular resistance or 36 +/- 7% increase in vascular conductance) and increases in brachial vascular tone (resistance increase of 10 +/- 6% and conductance decrease of 11 +/- 4%). Relatively small changes (<5%) in renal vascular tone were observed. In contrast, electrical stimulation of muscle and cutaneous afferents produced pressor responses (20 +/- 6 mmHg) that were accompanied by vasoconstriction in all three beds. These data suggest that vestibular inputs lead to a complex pattern of cardiovascular changes that is distinct from that which occurs in response to activation of other types of somatic afferents.

Kerman, I. A.; Emanuel, B. A.; Yates, B. J.

2000-01-01

241

Gait intiation in bilateral vestibular loss  

Microsoft Academic Search

Objective: Gait initiation is a transient procedure between orthostatic posture and steady-state locomotion and includes anticipatory anteroposterior (AP) and lateral movements. Commands for this task are located in some levels of brain stem, which modulates activity of central pattern generator in the spinal cord. The purpose of this work was to explore the role of the vestibular system in this

Osamu Sasaki; Shiro Asawa; Satoshi Katsuno; Shin-ichi Usami; Kiichiro Taguchi

2001-01-01

242

Perspectives in vestibular diagnostics and therapy  

PubMed Central

Vestibular diagnostics and therapy ist the mirror of technological, scientific and socio-economics trends as are other fields of clinical medicine. These trends have led to a substantial diversification of the field of neurotology. The improvements in diagnostics have been characterized by the introduction of new receptor testing tools (e.g., VEMPs), progress in imaging (e.g., the endolymphatic hydrops) and in the description of central-vestibular neuroplasticity. The etiopathology of vestibular disorders has been updated by geneticists (e.g., the description of the COCH gene mutations), the detection of structural abnormalities (e.g., dehiscence syndromes) and related disorders (e.g. migraine-associated vertigo). The therapeutic options were extended by re-evaluation of techniques known a long time ago (e.g., saccus exposure), the development of new approaches (e.g., dehiscence repair) and the introduction of new drug therapy concepts (e.g., local drug delivery). Implantable, neuroprosthetic solutions have not yet reached experimental safety and validity and are still far away. However, externally worn neuroprosthetic solution were introduced in the rehab of vestibular disorders (e.g., VertiGuard system). These and related trends point into a medical future which is characterized by presbyvertigo as classical sign of the demographic changes ahead, by shortage of financial resources and a medico-legally over-regulated, even hostile environment for physicians in clinical medicine. PMID:22558055

Ernst, Arneborg

2012-01-01

243

Vestibular evoked myogenic potentials in Bell's palsy.  

PubMed

The aim of the present study was to evaluate vestibular nerve involvement in patients with Bell's palsy with ocular and cervical vestibular evoked myogenic potentials (oVEMP and cVEMP). Ten patients who were diagnosed with Bell's palsy and ten healthy controls were included. All patients underwent VEMP recordings within 6 days after their initial presentation. Patients with Bell's palsy had greater oVEMP asymmetry ratio comparing to healthy controls (-38.4 ± 28.7 % vs -1.3 ± 19.3 %, p = 0.005). As well N10 latencies of the oVEMP response were prolonged comparing to healthy controls (11.575 vs 9.72 ms). There was no difference in cVEMP asymmetry ratio or latencies between groups. We found no correlation between House-Brackmann grading scale and oVEMP asymmetry ratio (r = 0.003, p = 0.994). There are three possible explanations for increased oVEMP amplitudes on the affected side: (1) oVEMP response on the ipsilateral eye could be contaminated by facial nerve activity (blink reflex); (2) the amplitude of N10-P33 could be affected through the stapedial reflex; and (3) increased oVEMP amplitude could be the consequence of the vestibular nerve dysfunction itself, with prolonged latencies of the N10 oVEMP further supporting this explanation. The results of this study indicate possible involvement of the superior branch of the vestibular nerve in patients with Bell's palsy. PMID:24916836

Krbot Skoric, Magdalena; Adamec, Ivan; Habek, Mario

2014-10-01

244

Postural compensation for unilateral vestibular loss.  

PubMed

Postural control of upright stance was investigated in well-compensated, unilateral vestibular loss (UVL) subjects compared to age-matched control subjects. The goal was to determine how sensory weighting for postural control in UVL subjects differed from control subjects, and how sensory weighting related to UVL subjects' functional compensation, as assessed by standardized balance and dizziness questionnaires. Postural control mechanisms were identified using a model-based interpretation of medial-lateral center-of-mass body-sway evoked by support-surface rotational stimuli during eyes-closed stance. The surface-tilt stimuli consisted of continuous pseudorandom rotations presented at four different amplitudes. Parameters of a feedback control model were obtained that accounted for each subject's sway response to the surface-tilt stimuli. Sensory weighting factors quantified the relative contributions to stance control of vestibular sensory information, signaling body-sway relative to earth-vertical, and proprioceptive information, signaling body-sway relative to the surface. Results showed that UVL subjects made significantly greater use of proprioceptive, and therefore less use of vestibular, orientation information on all tests. There was relatively little overlap in the distributions of sensory weights measured in UVL and control subjects, although UVL subjects varied widely in the amount they could use their remaining vestibular function. Increased reliance on proprioceptive information by UVL subjects was associated with their balance being more disturbed by the surface-tilt perturbations than control subjects, thus indicating a deficiency of balance control even in well-compensated UVL subjects. Furthermore, there was some tendency for UVL subjects who were less able to utilize remaining vestibular information to also indicate worse functional compensation on questionnaires. PMID:21922014

Peterka, Robert J; Statler, Kennyn D; Wrisley, Diane M; Horak, Fay B

2011-01-01

245

Postural Compensation for Unilateral Vestibular Loss  

PubMed Central

Postural control of upright stance was investigated in well-compensated, unilateral vestibular loss (UVL) subjects compared to age-matched control subjects. The goal was to determine how sensory weighting for postural control in UVL subjects differed from control subjects, and how sensory weighting related to UVL subjects’ functional compensation, as assessed by standardized balance and dizziness questionnaires. Postural control mechanisms were identified using a model-based interpretation of medial–lateral center-of-mass body-sway evoked by support-surface rotational stimuli during eyes-closed stance. The surface-tilt stimuli consisted of continuous pseudorandom rotations presented at four different amplitudes. Parameters of a feedback control model were obtained that accounted for each subject’s sway response to the surface-tilt stimuli. Sensory weighting factors quantified the relative contributions to stance control of vestibular sensory information, signaling body-sway relative to earth-vertical, and proprioceptive information, signaling body-sway relative to the surface. Results showed that UVL subjects made significantly greater use of proprioceptive, and therefore less use of vestibular, orientation information on all tests. There was relatively little overlap in the distributions of sensory weights measured in UVL and control subjects, although UVL subjects varied widely in the amount they could use their remaining vestibular function. Increased reliance on proprioceptive information by UVL subjects was associated with their balance being more disturbed by the surface-tilt perturbations than control subjects, thus indicating a deficiency of balance control even in well-compensated UVL subjects. Furthermore, there was some tendency for UVL subjects who were less able to utilize remaining vestibular information to also indicate worse functional compensation on questionnaires. PMID:21922014

Peterka, Robert J.; Statler, Kennyn D.; Wrisley, Diane M.; Horak, Fay B.

2011-01-01

246

Vestibular function in families with inherited autosomal dominant hearing loss  

PubMed Central

The inner ear contains the developmentally related cochlea and peripheral vestibular labyrinth. Given the similar physiology between these two organs, hearing loss and vestibular dysfunction may be expected to occur simultaneously in individuals segregating mutations in inner ear genes. Twenty-two different genes have been discovered that when mutated lead to non-syndromic autosomal dominant hearing loss. A review of the literature indicates that families segregating mutations in 13 of these 22 genes have undergone formal clinical vestibular testing. Formal assessment revealed vestibular dysfunction in families with mutations in ten of these 13 genes. Remarkably, only families with mutations in the COCH and MYO7A genes self-report considerable vestibular challenges. Families segregating mutations in the other eight genes do not self-report significant balance problems and appear to compensate well in everyday life for vestibular deficits discovered during formal clinical vestibular assessment. An example of a family (referred to as the HL1 family) with progressive hearing loss and clinically-detected vestibular hypofunction that does not report vestibular symptoms is described in this review. Notably, one member of the HL1 family with clinically-detected vestibular hypofunction reached the summit of Mount Kilimanjaro. PMID:18776598

Street, Valerie A.; Kallman, Jeremy C.; Strombom, Paul D.; Bramhall, Naomi F.; Phillips, James O.

2008-01-01

247

Vestibular Function and Quality of Life in Vestibular Schwannoma: Does Size Matter?  

PubMed Central

Objectives: Patients with vestibular schwannoma (VS) frequently suffer from disabling vestibular symptoms. This prospective follow-up study evaluates vestibular and auditory function and impairment of quality of life due to vertigo, dizziness, and imbalance in patients with unilateral VS of different sizes before/after microsurgical or radiosurgical treatment. Methods: Thirty-eight patients with unilateral VS were included. Twenty-two received microsurgery, 16 CyberKnife radiosurgery. Two follow-ups took place after a median of 50 and 186.5?days. Patients received a standardized neuro-ophthalmological examination, electronystagmography with bithermal caloric testing, and pure-tone audiometry. Quality of life was evaluated with the Dizziness Handicap Inventory (DHI). Patient data was grouped and analyzed according to the size of the VS (group 1: <20?mm vs group 2: ?20?mm). Results: In group 1, the median loss of vestibular function was +10.5% as calculated by Jongkees Formula (range ?43 to +52; group 2: median +36%, range ?56 to +90). The median change of DHI scores was ?9 in group 1 (range ?68 to 30) and +2 in group 2 (?54;+20). Median loss of hearing was 4?dB (?42; 93) in group 1 and 12?dB in group 2 (5; 42). Conclusion: Loss of vestibular function in VS clearly correlates with tumor size. However, loss of vestibular function was not strictly associated with a long-term deterioration of quality of life. This may be due to central compensation of vestibular deficits in long-standing large tumors. Loss of hearing before treatment was significantly influenced by the age of the patient but not by tumor size. At follow-up 1 and 2, hearing was significantly influenced by the size of the VS and the manner of treatment. PMID:21941519

Wagner, Judith Nastjenka; Glaser, Miriam; Wowra, Berndt; Muacevic, Alexander; Goldbrunner, Roland; Cnyrim, Christian; Tonn, Jörg-Christian; Strupp, Michael

2011-01-01

248

Recovery of vestibular function following hair cell destruction by streptomycin  

NASA Technical Reports Server (NTRS)

Can the vestibular periphery of warm-blooded vertebrates recover functionally from severe sensory hair cell loss? Recent findings in birds suggest a mechanism for recovery but in fact no direct functional evidence has been reported. We produced vestibular hair cell lesions using the ototoxic agent streptomycin sulfate (600 mg/kg/day, 8 days, chicks, Gallus domesticus). Compound action potentials of the vestibular nerve were used as a direct measure of peripheral vestibular function. Vestibular thresholds, neural activation latencies and amplitudes were documented. Eight days of drug treatment elevated thresholds significantly (P < 0.001) and eliminated all but remnants of vestibular activity. Virtually complete physiological recovery occurred in all animals studied over a period of 70 days following treatment. Thresholds recovered within two weeks of drug treatment whereas the return of response morphologies including activation latencies and amplitudes required an additional 6-8 weeks.

Jones, T. A.; Nelson, R. C.

1992-01-01

249

Diverse spatial reference frames of vestibular signals in parietal cortex  

PubMed Central

Summary Reference frames are important for understanding how sensory cues from different modalities are coordinated to guide behavior, and the parietal cortex is critical to these functions. We compare reference frames of vestibular self-motion signals in the ventral intraparietal area (VIP), parietoinsular vestibular cortex (PIVC), and dorsal medial superior temporal area (MSTd). Vestibular heading tuning in VIP is invariant to changes in both eye and head positions, indicating a body (or world)-centered reference frame. Vestibular signals in PIVC have reference frames that are intermediate between head- and body-centered. In contrast, MSTd neurons show reference frames between head- and eye-centered, but not body-centered. Eye and head position gain fields were strongest in MSTd and weakest in PIVC. Our findings reveal distinct spatial reference frames for representing vestibular signals, and pose new challenges for understanding the respective roles of these areas in potentially diverse vestibular functions. PMID:24239126

Chen, Xiaodong; DeAngelis, Gregory C; Angelaki, Dora E

2013-01-01

250

Asymmetry of balance responses to monaural galvanic vestibular stimulation in subjects with vestibular schwannoma?  

PubMed Central

Objective We investigated the potential of galvanic vestibular stimulation (GVS) to quantify lateralised asymmetry of the vestibulospinal pathways by measuring balance responses to monaural GVS in 10 subjects with vestibular schwannoma and 22 healthy control subjects. Methods Subjects standing without vision were stimulated with 3 s, 1 mA direct current stimuli delivered monaurally. The mean magnitude and direction of the evoked balance responses in the horizontal plane were measured from ground-reaction forces and from displacement and velocity of the trunk. Vestibular-evoked myogenic potentials (VEMPs) to 500 Hz air and bone-conducted tones were also recorded. Results In healthy subjects, the magnitudes of the force, velocity and displacement responses were not significantly different for left compared to right ear stimulation. Their individual asymmetry ratios were always <30%. Subjects with vestibular schwannoma had significantly smaller force, velocity and displacement responses to stimulation of the affected compared with non-affected ear. Their mean asymmetry ratios were significantly elevated for all three measures (41.2 ± 10.3%, 40.3 ± 15.1% and 21.9 ± 14.6%). Conclusions Asymmetry ratios of balance responses to monaural GVS provide a quantitative and clinically applicable lateralising test of the vestibulospinal pathways. Significance This method offers a more clinically relevant measure of standing balance than existing vestibular function tests which assess only vestibuloocular and vestibulocollic pathways. PMID:23643313

Welgampola, Miriam S.; Ramsay, Elijane; Gleeson, Michael J.; Day, Brian L.

2013-01-01

251

New methods for diagnosis and treatment of vestibular diseases  

PubMed Central

Dizziness and vertigo are common complaints, with a lifetime prevalence of over 30%. This review provides a brief summary of the recent diagnostic and therapeutic advances in the field of neuro-otology. A special focus is placed on the clinical usefulness of vestibular tests. While these have markedly improved over the years, treatment options for vestibular disorders still remain limited. Available therapies for selected vestibular diseases are discussed. PMID:21173877

Palla, Antonella

2010-01-01

252

Ocular-Vestibular Integration, Height Anxiety and the Environmental Vertical Illusion.  

E-print Network

??The ocular-vestibular system integrates visual, vestibular, and proprioceptive information in order to aid individuals in navigating the environment. Individual differences arise in the relative weight… (more)

Willey, Chela

2012-01-01

253

Enlarged vestibular aqueduct: Looking for genotypic-phenotypic correlations.  

PubMed

The aim of this work is to provide a guide for clinical and genetic diagnosis and classification of the enlarged vestibular aqueduct syndrome based on a review of the literature and computerized databases with the words large and enlarged vestibular aqueduct. No more than 40 articles described association between the EVA phenotype and a known genetic alteration. Pendred's syndrome, distal renal tubular acidosis, waardenburg's syndrome, X-linked congenital mixed deafness, branchio-oto-renal syndrome, and oto-facio-cervical syndrome can express their genotypic alteration as enlarged vestibular aqueduct syndrome. We also found articles reporting familiar cases of enlarged vestibular aqueduct with no identified mutations in studied genes. PMID:16830115

González-García, José Angel; Ibáńez, Andrés; Ramírez-Camacho, Rafael; Rodríguez, Antonio; García-Berrocal, José Ramón; Trinidad, Almudena

2006-11-01

254

Task, muscle and frequency dependent vestibular control of posture.  

PubMed

The vestibular system is crucial for postural control; however there are considerable differences in the task dependence and frequency response of vestibular reflexes in appendicular and axial muscles. For example, vestibular reflexes are only evoked in appendicular muscles when vestibular information is relevant to postural control, while in neck muscles they are maintained regardless of the requirement to maintain head on trunk balance. Recent investigations have also shown that the bandwidth of vestibular input on neck muscles is much broader than appendicular muscles (up to a factor of 3). This result challenges the notion that vestibular reflexes only contribute to postural control across the behavioral and physiological frequency range of the vestibular organ (i.e., 0-20 Hz). In this review, we explore and integrate these task-, muscle- and frequency-related differences in the vestibular system's contribution to posture, and propose that the human nervous system has adapted vestibular signals to match the mechanical properties of the system that each group of muscles controls. PMID:25620919

Forbes, Patrick A; Siegmund, Gunter P; Schouten, Alfred C; Blouin, Jean-Sébastien

2014-01-01

255

Task, muscle and frequency dependent vestibular control of posture  

PubMed Central

The vestibular system is crucial for postural control; however there are considerable differences in the task dependence and frequency response of vestibular reflexes in appendicular and axial muscles. For example, vestibular reflexes are only evoked in appendicular muscles when vestibular information is relevant to postural control, while in neck muscles they are maintained regardless of the requirement to maintain head on trunk balance. Recent investigations have also shown that the bandwidth of vestibular input on neck muscles is much broader than appendicular muscles (up to a factor of 3). This result challenges the notion that vestibular reflexes only contribute to postural control across the behavioral and physiological frequency range of the vestibular organ (i.e., 0–20 Hz). In this review, we explore and integrate these task-, muscle- and frequency-related differences in the vestibular system’s contribution to posture, and propose that the human nervous system has adapted vestibular signals to match the mechanical properties of the system that each group of muscles controls. PMID:25620919

Forbes, Patrick A.; Siegmund, Gunter P.; Schouten, Alfred C.; Blouin, Jean-Sébastien

2015-01-01

256

What is the minimal vestibular function required for compensation?  

NASA Technical Reports Server (NTRS)

Living with an uncompensated, abnormal vestibular system requires oppressive modification of life style and often prevents return to work and activities of daily living. Patients with vestibular abnormalities were studied to determine the minimal residual vestibular function required to achieve compensation. Three groups of patients with (a) complete unilateral loss of vestibular function with normal horizontal canal-vestibulo-ocular (HCVOR) function in the opposite ear, (b) complete unilateral loss with abnormal HCVOR function in the opposite ear, and (c) bilateral reduction of vestibular function from aminoglycoside toxicity underwent vestibuloocular (VOR), optokinetic (OKN), visual-VOR (VVOR), and computerized dynamic posturography (CDP) tests before and after therapeutic procedures. Results suggest that a minimal VOR response amplitude must be present for compensation of VVOR function to occur. The roles of VOR and OKN phase shifts in vestibular compensation are more complicated and require further study. Compensation of vestibulospinal function does not necessarily accompany VOR or VVOR compensation. Ascending and descending vestibular compensatory mechanisms may involve different spatial sensory inputs. Results of these studies have important implications for the diagnosis and treatment of patients with vestibular disorders, including selection and monitoring of patients for therapeutic regimens such as vestibular nerve section and streptomycin therapy.

Black, F. O.; Wade, S. W.; Nashner, L. M.

1996-01-01

257

Direction Specific Biases in Human Visual and Vestibular Heading Perception  

PubMed Central

Heading direction is determined from visual and vestibular cues. Both sensory modalities have been shown to have better direction discrimination for headings near straight ahead. Previous studies of visual heading estimation have not used the full range of stimuli, and vestibular heading estimation has not previously been reported. The current experiments measure human heading estimation in the horizontal plane to vestibular, visual, and spoken stimuli. The vestibular and visual tasks involved 16 cm of platform or visual motion. The spoken stimulus was a voice command speaking a heading angle. All conditions demonstrated direction dependent biases in perceived headings such that biases increased with headings further from the fore-aft axis. The bias was larger with the visual stimulus when compared with the vestibular stimulus in all 10 subjects. For the visual and vestibular tasks precision was best for headings near fore-aft. The spoken headings had the least bias, and the variation in precision was less dependent on direction. In a separate experiment when headings were limited to ±45°, the biases were much less, demonstrating the range of headings influences perception. There was a strong and highly significant correlation between the bias curves for visual and spoken stimuli in every subject. The correlation between visual-vestibular and vestibular-spoken biases were weaker but remained significant. The observed biases in both visual and vestibular heading perception qualitatively resembled predictions of a recent population vector decoder model (Gu et al., 2010) based on the known distribution of neuronal sensitivities. PMID:23236490

Crane, Benjamin T.

2012-01-01

258

Vestibular-ocular accommodation reflex in man  

NASA Technical Reports Server (NTRS)

Stimulation of the vestibular system by angular acceleration produces widespread sensory and motor effects. The present paper studies a motor effect which has not been reported in the literature, i.e., the influence of rotary acceleration of the body on ocular accommodation. The accommodation of 10 young men was recorded before and after a high-level deceleration to zero velocity following 30 sec of rotating. Accommodation was recorded continuously on an infrared optometer for 110 sec under two conditions: while the subjects observed a target set at the far point, and while they viewed the same target through a 0.3-mm pinhole. Stimulation by high-level rotary deceleration produced positive accommodation or a pseudomyopia under both conditions, but the positive accommodation was substantially greater and lasted much longer during fixation through the pinhole. It is hypothesized that this increase in accommodation is a result of a vestibular-ocular accommodation reflex.

Clark, B.; Randle, R. J.; Stewart, J. D.

1975-01-01

259

The vestibular system of the owl  

NASA Technical Reports Server (NTRS)

Five owls were given vestibular examinations, and two of them were sacrificed to provide serial histological sections of the temporal bones. The owls exhibited a curious variability in the postrotatory head nystagmus following abrupt deceleration; sometimes a brisk nystagnus with direction opposite to that appropriate to the stimulus would occur promptly after deceleration. It was found also that owls can exhibit a remarkable head stability during angular movement of the body about any axis passing through the skull. The vestibular apparatus in the owl is larger than in man, and a prominent crista neglecta is present. The tectorial membrane, the cupula, and the otolithic membranes of the utricle, saccule, and lagena are all attached to surfaces in addition to the surfaces hearing hair cells. These attachments are very substantial in the utricular otolithic membrane and in the cupula.

Money, K. E.; Correia, M. J.

1973-01-01

260

Vestibular activation of sympathetic nerve activity  

NASA Technical Reports Server (NTRS)

AIM: The vestibulosympathetic reflex refers to sympathetic nerve activation by the vestibular system. Animal studies indicate that the vestibular system assists in blood pressure regulation during orthostasis. Although human studies clearly demonstrate activation of muscle sympathetic nerve activity (MSNA) during engagement of the otolith organs, the role of the vestibulosympathetic reflex in maintaining blood pressure during orthostasis is not well-established. Examination of the vestibulosympathetic reflex with other cardiovascular reflexes indicates that it is a powerful and independent reflex. Ageing, which is associated with an increased risk for orthostatic hypotension, attenuates the vestibulosympathetic reflex. The attenuated reflex is associated with a reduction in arterial pressure. CONCLUSION: These findings suggest that the vestibulosympathetic reflex assists in blood pressure regulation in humans, but future studies examining this reflex in other orthostatically intolerant populations are necessary to address this hypothesis.

Ray, C. A.; Carter, J. R.

2003-01-01

261

Vestibular efferent neurons project to the flocculus  

NASA Technical Reports Server (NTRS)

A bilateral projection from the vestibular efferent neurons, located dorsal to the genu of the facial nerve, to the cerebellar flocculus and ventral paraflocculus was demonstrated. Efferent neurons were double-labeled by the unilateral injections of separate retrograde tracers into the labyrinth and into the floccular and ventral parafloccular lobules. Efferent neurons were found with double retrograde tracer labeling both ipsilateral and contralateral to the sites of injection. No double labeling was found when using a fluorescent tracer with non-fluorescent tracers such as horseradish peroxidase (HRP) or biotinylated dextran amine (BDA), but large percentages of efferent neurons were found to be double labeled when using two fluorescent substances including: fluorogold, microruby dextran amine, or rhodamine labeled latex beads. These data suggest a potential role for vestibular efferent neurons in modulating the dynamics of the vestibulo-ocular reflex (VOR) during normal and adaptive conditions.

Shinder, M. E.; Purcell, I. M.; Kaufman, G. D.; Perachio, A. A.

2001-01-01

262

The reaction time to vestibular stimuli  

Microsoft Academic Search

The problem of this study was to determine the reaction time of voluntary response to the perception of passive rotary motion of the body with visual and auditory cues either masked or removed. Results are summarized as follows: (1) The average vestibular reaction time to passive body motion was 0.598 second, and the range from 0.190 to 1.79 second. (2)

B. Baxter; R. C. Travis

1938-01-01

263

Radiosurgery of residual and recurrent vestibular schwannomas.  

PubMed

Radiosurgery is either a primary or an adjunctive management approach used to treat patients with vestibular schwannomas. We sought to determine outcomes measuring the potential benefits against the neurological risks in patients who underwent radiosurgery after previous microsurgical subtotal resection or recurrence of the tumour after total resection. Gamma Knife radiosurgery was applied as an adjunctive treatment modality for 86 patients with vestibular schwannomas from April 1992 to August 2001. We evaluated the results of 50 patients who had a follow-up of at least 3.5 years (median 75 months, range 42-114 months). In 16 patients a recurrence of disease was observed after previous total resection. The median treatment volume was 3.4 ccm with a median dose to the tumour margin of 13 Gy. Tumour control rate was 96%. Two tumours progressed after adjunctive radiosurgery. Useful hearing (Gardner-Robertson II) (4 patients (8%)) and residual hearing (Gardner-Roberson III) (10 patients (20%)) remained unchanged in all patients, who presented with it before radiosurgery, respectively. Clinical neurological improvement was observed in 24 patients (46%). Adverse effects comprised transient neurological symptoms and signs (incomplete facial palsy, House-Brackman II/III) in five cases (recovered completely), mild trigeminal neuropathy in four cases, and morphological changes displaying rapid enlargement of a pre-existing macrocyst in one patient and tumour growth in another one. No permanent new cranial nerve deficit was observed. Radiosurgery appears to be an effective adjunctive method for growth control of vestibular schwannomas and is associated with both a low mortality rate and a good quality of life. Accordingly, radiosurgery is a rewarding therapeutic approach for the preservation of cranial nerve function in the management of patients with vestibular schwannoma in whom prior microsurgical resection failed. PMID:12181700

Unger, F; Walch, C; Papaefthymiou, G; Feichtinger, K; Trummer, M; Pendl, G

2002-07-01

264

The vestibular control of balance after stroke  

PubMed Central

Objectives: To examine vestibular control of balance in those who recovered the ability to stand after middle cerebral artery (MCA) stroke. Methods: Sixteen patients with MCA stroke were compared with 10 age matched controls. Two additional patients were studied with isolated corticospinal tract lesions, one each at the level of the pons and medulla. Vestibular evoked postural responses were obtained using galvanic vestibular stimulation (GVS) while patients stood with their eyes closed and head facing forwards, equally loading both legs. The GVS response was characterised by measuring the amplitude of the stimulus evoked lateral forces acting through each leg and the lateral displacement of the axial skeleton. Results: Lateral displacement and net lateral force following GVS were significantly larger after stroke. Unlike controls, the lateral forces in the stroke group were asymmetrical, being enhanced on the side of the non-paretic limb and small on the side of the paretic limb. The degree of GVS evoked asymmetry correlated with corticospinal damage assessed using transcranial magnetic stimulation. A similar asymmetrical response was seen in the patient with the pontine lesion but not the patient with the medullary lesion. Conclusions: MCA stroke may disrupt corticobulbar projections to brainstem output pathways involved in vestibular control of balance. These projections are either collaterals of the corticospinal tract or lie close to that tract and terminate in the pons/upper medulla. This hypothesis accounts for the association between corticospinal tract damage and GVS response asymmetry, and the lack of GVS evoked asymmetry with corticospinal lesions below the rostral medulla. PMID:15834025

Marsden, J; Playford, D; Day, B

2005-01-01

265

Resonance  

NSDL National Science Digital Library

All About Circuits is a website that â??provides a series of online textbooks covering electricity and electronics.â?ť Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This specific section, Resonance, is the sixth chapter in the Volume II textbook. Topics covered in this chapter include: electric pendulum, simple parallel resonance, simple series resonance, resonance in series-parallel circuits, and Q and bandwidth of a resonant circuit. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

266

Differential central projections of vestibular afferents in pigeons  

NASA Technical Reports Server (NTRS)

The question of whether a differential distribution of vestibular afferent information to central nuclear neurons is present in pigeons was studied using neural tracer compounds. Discrete tracing of afferent fibers innervating the individual semicircular canal and otolith organs was produced by sectioning individual branches of the vestibular nerve that innervate the different receptor organs and applying crystals of horseradish peroxidase, or a horseradish peroxidase/cholera toxin mixture, or a biocytin compound for neuronal uptake and transport. Afferent fibers and their terminal distributions within the brainstem and cerebellum were visualized subsequently. Discrete areas in the pigeon central nervous system that receive primary vestibular input include the superior, dorsal lateral, ventral lateral, medial, descending, and tangential vestibular nuclei; the A and B groups; the intermediate, medial, and lateral cerebellar nuclei; and the nodulus, the uvula, and the paraflocculus. Generally, the vertical canal afferents projected heavily to medial regions in the superior and descending vestibular nuclei as well as the A group. Vertical canal projections to the medial and lateral vestibular nuclei were observed but were less prominent. Horizontal canal projections to the superior and descending vestibular nuclei were much more centrally located than those of the vertical canals. A more substantial projection to the medial and lateral vestibular nuclei was seen with horizontal canal afferents compared to vertical canal fibers. Afferents innervating the utricle and saccule terminated generally in the lateral regions of all vestibular nuclei in areas that were separate from the projections of the semicircular canals. In addition, utricular fibers projected to regions in the vestibular nuclei that overlapped with the horizontal semicircular canal terminal fields, whereas saccular afferents projected to regions that received vertical canal fiber terminations. Lagenar afferents projected throughout the cochlear nuclei, to the dorsolateral regions of the cerebellar nuclei, and to lateral regions of the superior, lateral, medial, and descending vestibular nuclei.

Dickman, J. D.; Fang, Q.

1996-01-01

267

Otolith-Canal Convergence in Vestibular Nuclei Neurons  

NASA Technical Reports Server (NTRS)

During manned spaceflight, acute vestibular disturbances often occur, leading to physical duress and a loss of performance. Vestibular adaptation to the weightless environment follows within two to three days yet the mechanisms responsible for the disturbance and subsequent adaptation are still unknown In order to understand vestibular system function in space and normal earth conditions the basic physiological mechanisms of vestibular information co coding must be determined. Information processing regarding head movement and head position with respect to gravity takes place in the vestibular nuclei neurons that receive signals From the semicircular canals and otolith organs in the vestibular labyrinth. These neurons must synthesize the information into a coded output signal that provides for the head and eye movement reflexes as well as the conscious perception of the body in three-dimensional space The current investigation will for the first time. determine how the vestibular nuclei neurons quantitatively synthesize afferent information from the different linear and angular acceleration receptors in the vestibular labyrinths into an integrated output signal. During the second year of funding, progress on the current project has been focused on the anatomical orientation of semicircular canals and the spatial orientation of the innervating afferent responses. This information is necessary in order to understand how vestibular nuclei neurons process the incoming afferent spatial signals particularly with the convergent otolith afferent signals that are also spatially distributed Since information from the vestibular nuclei is presented to different brain regions associated with differing reflexive and sensory functions it is important to understand the computational mechanisms used by vestibular neurons to produce the appropriate output signal.

Dickman, J. David

1996-01-01

268

A Structure-Based Simulation Approach for Electron Paramagnetic Resonance Spectra Using Molecular and Stochastic Dynamics Simulations  

Microsoft Academic Search

Electron paramagnetic resonance (EPR) spectroscopy using site-directed spin-labeling is an appropriate technique to analyze the structure and dynamics of flexible protein regions as well as protein-protein interactions under native conditions. The analysis of a set of protein mutants with consecutive spin-label positions leads to the identification of secondary and tertiary structure elements. In the first place, continuous-wave EPR spectra reflect

Christian Beier; Heinz-Jürgen Steinhoff

2006-01-01

269

Vestibular Dreams: The Effect of Rocking on Dream Mentation  

Microsoft Academic Search

The study investigates the proposed link between vestibular activation and dream lucidity. In the experiment, subjects spent two consecutive nights sleeping in a hammock in the sleep lab. For each night, during the second, third, and fourth REM sleep periods, the hammock was either stationary (control condition), or rocked at a constant frequency (experimental condition) stimulating the subject’s vestibular system.

Kenneth Leslie; Robert Ogilvie

1996-01-01

270

Vestibular influences on autonomic cardiovascular control in humans  

NASA Technical Reports Server (NTRS)

There is substantial evidence that anatomical connections exist between vestibular and autonomic nuclei. Animal studies have shown functional interactions between the vestibular and autonomic systems. The nature of these interactions, however, is complex and has not been fully defined. Vestibular stimulation has been consistently found to reduce blood pressure in animals. Given the potential interaction between vestibular and autonomic pathways this finding could be explained by a reduction in sympathetic activity. However, rather than sympathetic inhibition, vestibular stimulation has consistently been shown to increase sympathetic outflow in cardiac and splanchnic vascular beds in most experimental models. Several clinical observations suggest that a link between vestibular and autonomic systems may also exist in humans. However, direct evidence for vestibular/autonomic interactions in humans is sparse. Motion sickness has been found to induce forearm vasodilation and reduce baroreflex gain, and head down neck flexion induces transient forearm and calf vasoconstriction. On the other hand, studies using optokinetic stimulation have found either very small, variable, or inconsistent changes in heart rate and blood pressure, despite substantial symptoms of motion sickness. Furthermore, caloric stimulation severe enough to produce nystagmus, dizziness, and nausea had no effect on sympathetic nerve activity measured directly with microneurography. No effect was observed on heart rate, blood pressure, or plasma norepinephrine. Several factors may explain the apparent discordance of these results, but more research is needed before we can define the potential importance of vestibular input to cardiovascular regulation and orthostatic tolerance in humans.

Biaggioni, I.; Costa, F.; Kaufmann, H.; Robertson, D. (Principal Investigator)

1998-01-01

271

Evidence for cognitive vestibular integration impairment in idiopathic scoliosis patients  

PubMed Central

Background Adolescent idiopathic scoliosis is characterized by a three-dimensional deviation of the vertebral column and its etiopathogenesis is unknown. Various factors cause idiopathic scoliosis, and among these a prominent role has been attributed to the vestibular system. While the deficits in sensorimotor transformations have been documented in idiopathic scoliosis patients, little attention has been devoted to their capacity to integrate vestibular information for cognitive processing for space perception. Seated idiopathic scoliosis patients and control subjects experienced rotations of different directions and amplitudes in the dark and produced saccades that would reproduce their perceived spatial characteristics of the rotations (vestibular condition). We also controlled for possible alteration of the oculomotor and vestibular systems by measuring the subject's accuracy in producing saccades towards memorized peripheral targets in absence of body rotation and the gain of their vestibulo-ocular reflex. Results Compared to healthy controls, the idiopathic scoliosis patients underestimated the amplitude of their rotations. Moreover, the results revealed that idiopathic scoliosis patients produced accurate saccades to memorized peripheral targets in absence of body rotation and that their vestibulo-ocular reflex gain did not differ from that of control participants. Conclusion Overall, results of the present study demonstrate that idiopathic scoliosis patients have an alteration in cognitive integration of vestibular signals. It is possible that severe spine deformity developed partly due to impaired vestibular information travelling from the cerebellum to the vestibular cortical network or alteration in the cortical mechanisms processing the vestibular signals. PMID:19706173

Simoneau, Martin; Lamothe, Vincent; Hutin, Émilie; Mercier, Pierre; Teasdale, Normand; Blouin, Jean

2009-01-01

272

Vestibular evoked myogenic potentials (VEMPs): usefulness in clinical neurotology.  

PubMed

Testing vestibular evoked myogenic potentials (VEMPs) may be the most important new clinical test for evaluation of vestibular function developed during the past 100 years since the introduction of the caloric test. VEMPs are easily recordable and therefore suitable for everyday testing in clinical neurotology. VEMPs in response to air-conducted sound stimulation using surface electrodes over the sternocleidomastoid muscles reveal saccular function, inferior vestibular nerve function, and vestibulocollic connections. At present, VEMPs are of clinical importance for estimating the severity of peripheral vestibular damage due to different pathophysiologic processes such as Méničre's disease, vestibular neuritis, and vestibular schwannoma. VEMPs can also be used to document vestibular hypersensitivity to sounds (Tullio phenomenon). In addition, VEMP testing constitutes an electrophysiologic method that is able to detect subclinical lesions in central vestibular pathways in patients with multiple sclerosis. In the near future, testing ocular VEMPs (OVEMPs) in response to bone-conducted vibration may prove to be of clinical importance for the evaluation of utricular function. PMID:19834866

Brantberg, Krister

2009-11-01

273

Dynamic tilt thresholds are reduced in vestibular migraine.  

PubMed

Vestibular symptoms caused by migraine, referred to as vestibular migraine, are a frequently diagnosed but poorly understood entity. Based on recent evidence that normal subjects generate vestibular-mediated percepts of head motion and reflexive eye movements using different mechanisms, we hypothesized that percepts of head motion may be abnormal in vestibular migraine. We therefore measured motion detection thresholds in patients with vestibular migraine, migraine patients with no history of vestibular symptoms, and normal subjects using the following paradigms: roll rotation while supine (dynamically activating the semicircular canals); quasi-static roll tilt (statically activating the otolith organs); and dynamic roll tilt (dynamically activating the canals and otoliths). Thresholds were determined while patients were asymptomatic using a staircase paradigm, whereby the peak acceleration of the motion was decreased or increased based on correct or incorrect reports of movement direction. We found a dramatic reduction in motion thresholds in vestibular migraine compared to normal and migraine subjects in the dynamic roll tilt paradigm, but normal thresholds in the roll rotation and quasi-static roll tilt paradigms. These results suggest that patients with vestibular migraine may have enhanced perceptual sensitivity (e.g. increased signal-to-noise ratio) for head motions that dynamically modulate canal and otolith inputs together. PMID:22348937

Lewis, Richard F; Priesol, Adrian J; Nicoucar, Keyvan; Lim, Koeun; Merfeld, Daniel M

2011-01-01

274

Sensory processing in the vestibular nuclei during active head movements  

NASA Technical Reports Server (NTRS)

Many secondary vestibular neurons are sensitive to head on trunk rotation during reflex-induced and voluntary head movements. During passive whole body rotation the interaction of head on trunk signals related to the vestibulo-collic reflex with vestibular signals increases the rotational gain of many secondary vestibular neurons, including many that project to the spinal cord. In some units, the sensitivity to head on trunk and vestibular input is matched and the resulting interaction produces an output that is related to the trunk velocity in space. In other units the head on trunk inputs are stronger and the resulting interaction produces an output that is larger during the reflex. During voluntary head movements, inputs related to head on trunk movement combine destructively with vestibular signals, and often cancel the sensory reafferent consequences of self-generated movements. Cancellation of sensory vestibular signals was observed in all of the antidromically identified secondary vestibulospinal units, even though many of these units were not significantly affected by reflexive head on trunk movements. The results imply that the inputs to vestibular neurons related to head on trunk rotation during reflexive and voluntary movements arise from different sources. We suggest that the relative strength of reflexive head on trunk input to different vestibular neurons might reflect the different functional roles they have in controlling the posture of the neck and body.

Gdowski, G. T.; Boyle, R.; McCrea, R. A.; Peterson, B. W. (Principal Investigator)

2000-01-01

275

Short communication Effectiveness of an electro-tactile vestibular substitution  

E-print Network

showed an asymmetry larger than 20%. To assess vestibular dysfunction, we first used a caloric test, during which bithermal caloric irrigation with cold (30 8C) and warm (44 8C) water was induced in the two of clinical tests. On the whole, a vestibular deficit was considered as unilateral if www

Payan, Yohan

276

Vestibular receptors contribute to cortical auditory evoked potentials?  

PubMed Central

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

Todd, Neil P.M.; Paillard, Aurore C.; Kluk, Karolina; Whittle, Elizabeth; Colebatch, James G.

2014-01-01

277

Detachment stabilization with n/m=1/1 resonant magnetic perturbation field applied to the stochastic magnetic boundary of the Large Helical Device  

SciTech Connect

It is found that the remnant island structure created by n/m=1/1 resonant magnetic perturbation field in the stochastic magnetic boundary of the Large Helical Device (LHD) [A. Komori et al., Nucl. Fusion 49, 104015 (2009)] has a stabilizing effect on formation of radiating plasma, realizing stably sustained divertor detachment operation with the core plasma being unaffected. The data from the several diagnostics, (profiles of electron temperature and density, radiation and temporal evolution of divertor particle flux) indicate selective cooling around X-point of the island and thus peaked radiation there, which is stabilized outside of the last closed flux surface throughout the detachment phase. The vacuum ultraviolet spectroscopy measurements of high Z impurity (iron) emission shows significant decrease during the detachment, indicating core plasma decontamination. The results from the three-dimensional (3D) edge transport code, edge Monte Carlo 3D (EMC3) [Y. Feng et al., Contrib. Plasma Phys. 44, 57 (2004)]-EIRENE [D. Reiter et al., Fusion Sci. Technol. 47, 172 (2005)] show similar tendency in the radiation pattern. The island size and its radial location are varied to investigate the magnetic topology effects on the detachment control. The divertor particle flux and neutral pressure exhibit intermittent oscillation as well as modification of recycling pattern during the detachment, which are found to reflect the island structure.

Kobayashi, M.; Masuzaki, S.; Yamada, I.; Tamura, N.; Sato, K.; Goto, M.; Narushima, Y.; Akiyama, T.; Miyazawa, J.; Shoji, M.; Morita, S.; Peterson, B. J.; Funaba, H.; Ohyabu, N.; Narihara, K.; Morisaki, T.; Yamada, H.; Komori, A. [National Institute for Fusion Science, Oroshi-cho 322-6, Toki city, Gifu 509-5292 (Japan); Feng, Y. [Max-Planck-Institut fuer Plasmaphysik, EURATOM-IPP Association, D-17491 Greifswald (Germany); Reiter, D. [Institut fuer Plasmaphysik, Forschungszentrum Juelich Gmbh, D-52425 Juelich (Germany)

2010-05-15

278

Clinical Manifestation and Prognosis of Vestibular Migraine According to the Vestibular Function Test Results  

PubMed Central

Background and Objectives According to previous reports, patients with vestibular migraine (VM) display variable results from vestibular function tests (VFT): central, peripheral, or normal. The aim of this study was to classify the VM patients into the three groups according to interictal VFT findings (central, peripheral or normal) and to clarify the relationship between VFT results and the clinical manifestations and prognosis in each group. Subjects and Methods We reviewed the medical records of 81 patients diagnosed as VM using the criteria of Neuhauser, et al. between December 2004 and June 2009. Patients were divided into three groups according to the results of VFT. We compared the clinical manifestations and prognosis between groups. Characteristics including dizziness, the nature of headache, associated otologic symptoms, hearing threshold, duration of illness, and recovery time were analyzed. Results The number of patients with central, peripheral vestibular dysfunction and normal finding in VFT were 15, 28, and 38 respectively. There were no significant differences in the nature of headache, associated otologic symptoms, hearing threshold, duration of illness, and recovery time. A small difference was observed in the mean age and characteristics of dizziness, but these were not significant. Conclusions In patients with VM, classification according to the type of vestibular dysfunction was not helpful in the prediction of prognosis and clinical manifestations. PMID:24653898

Lee, Jae-Wook; Jung, Jae Yun; Chung, You Sun

2013-01-01

279

A vestibular sensation: probabilistic approaches to spatial perception  

PubMed Central

The vestibular system helps maintain equilibrium and clear vision through reflexes, but it also contributes to spatial perception. In recent years, research in the vestibular field has expanded to higher level processing involving the cortex. Vestibular contributions to spatial cognition have been difficult to study because the circuits involved are inherently multisensory. Computational methods and the application of Bayes theorem are used to form hypotheses about how information from different sensory modalities is combined together with expectations based on past experience in order to obtain optimal estimates of cognitive variables like current spatial orientation. To test these hypotheses, neuronal populations are being recorded during active tasks in which subjects make decisions based on vestibular and visual or somatosensory information. This review highlights what is currently known about the role of vestibular information in these processes, the computations necessary to obtain the appropriate signals, and the benefits that have emerged thus far. PMID:19945388

Angelaki, Dora E.; Klier, Eliana M.; Snyder, Lawrence H.

2009-01-01

280

Postural and locomotor control in normal and vestibularly deficient mice  

PubMed Central

We investigated how vestibular information is used to maintain posture and control movement by studying vestibularly deficient mice (IsK?/? mutant). In these mutants, microscopy showed degeneration of the cristae of the semicircular canals and of the maculae of the utriculi and sacculi, while behavioural and vestibulo-ocular reflex testing showed that vestibular function was completely absent. However, the histology of Scarpa's ganglia and the vestibular nerves was normal in mutant mice, indicating the presence of intact central pathways. Using X-ray and high-speed cineradiography, we compared resting postures and locomotion patterns between these vestibularly deficient mice and vestibularly normal mice (wild-type and IsK+/?). The absence of vestibular function did not affect resting posture but had profound effects on locomotion. At rest, the S-shaped, sagittal posture of the vertebral column was the same for wild-type and mutant mice. Both held the head with the atlanto-occipital joint fully flexed, the cervico-thoracic junction fully flexed, and the cervical column upright. Wild-type mice extended the head and vertebral column and could walk in a straight line. In marked contrast, locomotion in vestibularly deficient mice was characterized by circling episodes, during which the vertebral column maintained an S-shaped posture. Thus, vestibular information is not required to control resting posture but is mandatory for normal locomotion. We propose that vestibular inputs are required to signal the completion of a planned trajectory because mutant mice continued rotating after changing heading direction. Our findings support the hypothesis that vertebrates limit the number of degrees of freedom to be controlled by adopting just a few of the possible skeletal configurations. PMID:15243133

Vidal, P-P; Degallaix, L; Josset, P; Gasc, J-P; Cullen, K E

2004-01-01

281

Vestibular prosthesis tested in rhesus monkeys.  

PubMed

We are studying the effectiveness of a semicircular canal prosthesis to improve postural control, perception of spatial orientation, and the VOR in rhesus monkeys with bilateral vestibular hypofunction. Balance is examined by measuring spontaneous sway of the body during quiet stance and postural responses evoked by head turns and rotation of the support surface; perception is measured with a task derived from the subjective visual vertical (SVV) test during static and dynamic rotation in the roll plane; and the angular VOR is measured during rotation about the roll, pitch, and yaw axes. After the normal responses are characterized, bilateral vestibular loss is induced with intratympanic gentamicin, and then multisite stimulating electrodes are chronically implanted into the ampullae of all three canals in one ear. The postural, perceptual, and VOR responses are then characterized in the ablated state, and then bilateral, chronic electrical stimulation is applied to the ampullary nerves using a prosthesis that senses angular head velocity in three-dimensions and uses this information to modulate the rate of current pulses provided by the implanted electrodes. We are currently characterizing two normal monkeys with these paradigms, and vestibular ablation and electrode implantation are planned for the near future. In one prior rhesus monkey tested with this approach, we found that a one-dimensional (posterior canal) prosthesis improved balance during head turns, perceived head orientation during roll tilts, and the VOR in the plane of the instrumented canal. We therefore predict that the more complete information provided by a three-dimensional prosthesis that modulates activity in bilaterally-paired canals will exceed the benefits provided by the one-dimensional, unilateral approach used in our preliminary studies. PMID:22254795

Lewis, Richard F; Haburcakova, Csilla; Gong, Wangsong; Lee, Daniel; Wall, Conrad; Thompson, Lara; Merfeld, Daniel M

2011-01-01

282

Developmental regulation of the membrane properties of central vestibular neurons by sensory vestibular information in the mouse  

PubMed Central

The effect of the lack of vestibular input on the membrane properties of central vestibular neurons was studied by using a strain of transgenic, vestibular-deficient mutant KCNE1?/? mice where the hair cells of the inner ear degenerate just after birth. Despite the absence of sensory vestibular input, their central vestibular pathways are intact. Juvenile and adult homozygous mutant have a normal resting posture, but show a constant head bobbing behaviour and display the shaker/waltzer phenotype characterized by rapid bilateral circling during locomotion. In juvenile mice, the KCNE1 mutation was associated with a strong decrease in the expression of the calcium-binding proteins calbindin, calretinin and parvalbumin within the medial vestibular nucleus (MVN) and important modifications of the membrane properties of MVN neurons. In adult mice, however, there was almost no difference between the membrane properties of MVN neurons of homozygous and control or heterozygous mutant mice, which have normal inner ear hair cells and show no behavioural symptoms. The expression levels of calbindin and calretinin were lower in adult homozygous mutant animals, but the amount of calcium-binding proteins expressed in the MVN was much greater than in juvenile mice. These data demonstrate that suppression of sensory vestibular inputs during a ‘sensitive period’ around birth can generate the circling/waltzing behaviour, but that this behaviour is not due to persistent abnormalities of the membrane properties of central vestibular neurons. Altogether, maturation of the membrane properties of central vestibular neurons is delayed, but not impaired by the absence of sensory vestibular information. PMID:17627998

Eugčne, D; Deforges, S; Guimont, F; Idoux, E; Vidal, P-P; Moore, L E; Vibert, N

2007-01-01

283

Altered vestibular function in fetal and newborn rats gestated in space  

NASA Technical Reports Server (NTRS)

Researchers evaluated vestibular development and function in rat pups flown during gestation on the NASA-NIH R1 and R2 missions. Fetal and postnatal vestibular function were examined. Altered vestibular-mediated responses in the experimental fetal pups are attributed to either direct effect of gravity on the vestibular system or indirect effects of microgravity transduced through the mother. The postnatal tests confirmed the hypothesis that the vestibular system continually adapts and responds to tonic stimulation.

Ronca, A. E.; Alberts, J. R.

1997-01-01

284

Neurogenic Potential of the Vestibular Nuclei and Behavioural Recovery Time Course in the Adult Cat Are Governed by the Nature of the Vestibular Damage  

PubMed Central

Functional and reactive neurogenesis and astrogenesis are observed in deafferented vestibular nuclei after unilateral vestibular nerve section in adult cats. The newborn cells survive up to one month and contribute actively to the successful recovery of posturo-locomotor functions. This study investigates whether the nature of vestibular deafferentation has an incidence on the neurogenic potential of the vestibular nuclei, and on the time course of behavioural recovery. Three animal models that mimic different vestibular pathologies were used: unilateral and permanent suppression of vestibular input by unilateral vestibular neurectomy (UVN), or by unilateral labyrinthectomy (UL, the mechanical destruction of peripheral vestibular receptors), or unilateral and reversible blockade of vestibular nerve input using tetrodotoxin (TTX). Neurogenesis and astrogenesis were revealed in the vestibular nuclei using bromodeoxyuridine (BrdU) as a newborn cell marker, while glial fibrillary acidic protein (GFAP) and glutamate decarboxylase 67 (GAD67) were used to identify astrocytes and GABAergic neurons, respectively. Spontaneous nystagmus and posturo-locomotor tests (static and dynamic balance performance) were carried out to quantify the behavioural recovery process. Results showed that the nature of vestibular loss determined the cellular plastic events occurring in the vestibular nuclei and affected the time course of behavioural recovery. Interestingly, the deafferented vestibular nuclei express neurogenic potential after acute and total vestibular loss only (UVN), while non-structural plastic processes are involved when the vestibular deafferentation is less drastic (UL, TTX). This is the first experimental evidence that the vestibular complex in the brainstem can become neurogenic under specific injury. These new data are of interest for understanding the factors favouring the expression of functional neurogenesis in adult mammals in a brain repair perspective, and are of clinical relevance in vestibular pathology. PMID:21853029

Dutheil, Sophie; Lacour, Michel; Tighilet, Brahim

2011-01-01

285

Vestibular Rehabilitation Therapy: Review of Indications, Mechanisms, and Key Exercises  

PubMed Central

Vestibular rehabilitation therapy (VRT) is an exercise-based treatment program designed to promote vestibular adaptation and substitution. The goals of VRT are 1) to enhance gaze stability, 2) to enhance postural stability, 3) to improve vertigo, and 4) to improve activities of daily living. VRT facilitates vestibular recovery mechanisms: vestibular adaptation, substitution by the other eye-movement systems, substitution by vision, somatosensory cues, other postural strategies, and habituation. The key exercises for VRT are head-eye movements with various body postures and activities, and maintaining balance with a reduced support base with various orientations of the head and trunk, while performing various upper-extremity tasks, repeating the movements provoking vertigo, and exposing patients gradually to various sensory and motor environments. VRT is indicated for any stable but poorly compensated vestibular lesion, regardless of the patient's age, the cause, and symptom duration and intensity. Vestibular suppressants, visual and somatosensory deprivation, immobilization, old age, concurrent central lesions, and long recovery from symptoms, but there is no difference in the final outcome. As long as exercises are performed several times every day, even brief periods of exercise are sufficient to facilitate vestibular recovery. Here the authors review the mechanisms and the key exercises for each of the VRT goals. PMID:22259614

Song, Hyun Seok; Kim, Ji Soo

2011-01-01

286

Pharmacotherapy of vestibular and ocular motor disorders, including nystagmus.  

PubMed

We review current pharmacological treatments for peripheral and central vestibular disorders, and ocular motor disorders that impair vision, especially pathological nystagmus. The prerequisites for successful pharmacotherapy of vertigo, dizziness, and abnormal eye movements are the "4 D's": correct diagnosis, correct drug, appropriate dosage, and sufficient duration. There are seven groups of drugs (the "7 A's") that can be used: antiemetics; anti-inflammatory, anti-Méničre's, and anti-migrainous medications; anti-depressants, anti-convulsants, and aminopyridines. A recovery from acute vestibular neuritis can be promoted by treatment with oral corticosteroids. Betahistine may reduce the frequency of attacks of Méničre's disease. The aminopyridines constitute a novel treatment approach for downbeat and upbeat nystagmus, as well as episodic ataxia type 2 (EA 2); these drugs may restore normal "pacemaker" activity to the Purkinje cells that govern vestibular and cerebellar nuclei. A limited number of trials indicate that baclofen improves periodic alternating nystagmus, and that gabapentin and memantine improve acquired pendular and infantile (congenital) nystagmus. Preliminary reports suggest suppression of square-wave saccadic intrusions by memantine, and ocular flutter by beta-blockers. Thus, although progress has been made in the treatment of vestibular neuritis, some forms of pathological nystagmus, and EA 2, controlled, masked trials are still needed to evaluate treatments for many vestibular and ocular motor disorders, including betahistine for Méničre's disease, oxcarbazepine for vestibular paroxysmia, or metoprolol for vestibular migraine. PMID:21461686

Strupp, Michael; Thurtell, Matthew J; Shaikh, Aasef G; Brandt, Thomas; Zee, David S; Leigh, R John

2011-07-01

287

Dysconnectivity Within the Default Mode in First-Episode Schizophrenia: A Stochastic Dynamic Causal Modeling Study With Functional Magnetic Resonance Imaging  

PubMed Central

We report the first stochastic dynamic causal modeling (sDCM) study of effective connectivity within the default mode network (DMN) in schizophrenia. Thirty-three patients (9 women, mean age = 25.0 years, SD = 5) with a first episode of psychosis and diagnosis of schizophrenia—according to the Diagnostic and Statistic Manual of Mental Disorders, 4th edition, revised criteria—were studied. Fifteen healthy control subjects (4 women, mean age = 24.6 years, SD = 4) were included for comparison. All subjects underwent resting state functional magnetic resonance imaging (fMRI) interspersed with 2 periods of continuous picture viewing. The anterior frontal (AF), posterior cingulate (PC), and the left and right parietal nodes of the DMN were localized in an unbiased fashion using data from 16 independent healthy volunteers (using an identical fMRI protocol). We used sDCM to estimate directed connections between and within nodes of the DMN, which were subsequently compared with t tests at the between subject level. The excitatory effect of the PC node on the AF node and the inhibitory self-connection of the AF node were significantly weaker in patients (mean values = 0.013 and ?0.048 Hz, SD = 0.09 and 0.05, respectively) relative to healthy subjects (mean values = 0.084 and ?0.088 Hz, SD = 0.15 and 0.77, respectively; P < .05). In summary, sDCM revealed reduced effective connectivity to the AF node of the DMN—reflecting a reduced postsynaptic efficacy of prefrontal afferents—in patients with first-episode schizophrenia. PMID:24939881

Bastos-Leite, António J.; Ridgway, Gerard R.; Silveira, Celeste; Norton, Andreia; Reis, Salomé; Friston, Karl J.

2015-01-01

288

Dysconnectivity within the default mode in first-episode schizophrenia: a stochastic dynamic causal modeling study with functional magnetic resonance imaging.  

PubMed

We report the first stochastic dynamic causal modeling (sDCM) study of effective connectivity within the default mode network (DMN) in schizophrenia. Thirty-three patients (9 women, mean age = 25.0 years, SD = 5) with a first episode of psychosis and diagnosis of schizophrenia-according to the Diagnostic and Statistic Manual of Mental Disorders, 4th edition, revised criteria-were studied. Fifteen healthy control subjects (4 women, mean age = 24.6 years, SD = 4) were included for comparison. All subjects underwent resting state functional magnetic resonance imaging (fMRI) interspersed with 2 periods of continuous picture viewing. The anterior frontal (AF), posterior cingulate (PC), and the left and right parietal nodes of the DMN were localized in an unbiased fashion using data from 16 independent healthy volunteers (using an identical fMRI protocol). We used sDCM to estimate directed connections between and within nodes of the DMN, which were subsequently compared with t tests at the between subject level. The excitatory effect of the PC node on the AF node and the inhibitory self-connection of the AF node were significantly weaker in patients (mean values = 0.013 and -0.048 Hz, SD = 0.09 and 0.05, respectively) relative to healthy subjects (mean values = 0.084 and -0.088 Hz, SD = 0.15 and 0.77, respectively; P < .05). In summary, sDCM revealed reduced effective connectivity to the AF node of the DMN-reflecting a reduced postsynaptic efficacy of prefrontal afferents-in patients with first-episode schizophrenia. PMID:24939881

Bastos-Leite, António J; Ridgway, Gerard R; Silveira, Celeste; Norton, Andreia; Reis, Salomé; Friston, Karl J

2015-01-01

289

The Development of the Vestibular Apparatus Under Conditions of Weightlessness  

NASA Technical Reports Server (NTRS)

A series of experiments has been carried out on the effect of space flight conditions on morphogenesis and the structure of the vestibular apparatus in amphibian and fish larvae. Larval development proceeded in weightlessness without serious morphological defects. The vestibular apparatus developed; its organization in the experimental animals did not differ qualitatively from that in the controls. The specific external stimulus (gravitation) appears not to be a necessary condition for the development of a gravitation receptor in ontogenesis although the appearance of the vestibular apparatus in phylogenesis was apparently related to this stimulus.

Vinnikov, Y. A.; Gazenko, O. G.; Lychakov, D. V.; Palmbakh, L. R.

1984-01-01

290

Weightlessness and the ontogeny of vestibular function - Evidence for persistent vestibular threshold shifts in chicks incubated in space  

NASA Technical Reports Server (NTRS)

The effect of microgravity on the embryonic development of the vestibular function was investigated by comparing the vestibular function parameters measured in 21-old chicks incubated as embryos aboard the Space Shuttle Discovery with those of age-matched synchronous controls incubated on earth. Measurements of the electrophysiological responses in both groups of chicks indicated that the exposure of embryos to weightlessness resulted in altered sensitivity of embryonic vestibular sensors. Moreover, the effect of space flight was persistent: it was still present one month after the spacecraft landed on earth.

Jones, Timothy A.; Vellinger, John; Hester, Patricia Y.; Fermin, Cesar

1991-01-01

291

Mutations of ESPN cause autosomal recessive deafness and vestibular dysfunction  

PubMed Central

We mapped a human deafness locus DFNB36 to chromosome 1p36.3 in two consanguineous families segregating recessively inherited deafness and vestibular areflexia. This phenotype co-segregates with either of two frameshift mutations, 1988delAGAG and 2469delGTCA, in ESPN, which encodes a calcium-insensitive actin-bundling protein called espin. A recessive mutation of ESPN is known to cause hearing loss and vestibular dysfunction in the jerker mouse. Our results establish espin as an essential protein for hearing and vestibular function in humans. The abnormal vestibular phenotype associated with ESPN mutations will be a useful clinical marker for refining the differential diagnosis of non-syndromic deafness. PMID:15286153

Naz, S; Griffith, A; Riazuddin, S; Hampton, L; Battey, J; Khan, S; Riazuddin, S; Wilcox, E; Friedman, T

2004-01-01

292

A vestibular prosthesis with highly-isolated parallel multichannel stimulation.  

PubMed

This paper presents an implantable vestibular stimulation system capable of providing high flexibility independent parallel stimulation to the semicircular canals in the inner ear for restoring three-dimensional sensation of head movements. To minimize channel interaction during parallel stimulation, the system is implemented with a power isolation method for crosstalk reduction. Experimental results demonstrate that, with this method, electrodes for different stimulation channels located in close proximity ( mm) can deliver current pulses simultaneously with minimum inter-channel crosstalk. The design features a memory-based scheme that manages stimulation to the three canals in parallel. A vestibular evoked potential (VEP) recording unit is included for closed-loop adaptive stimulation control. The main components of the prototype vestibular prosthesis are three ASICs, all implemented in a 0.6- ?m high-voltage CMOS technology. The measured performance was verified using vestibular electrodes in vitro. PMID:25073175

Jiang, Dai; Cirmirakis, Dominik; Demosthenous, Andreas

2015-02-01

293

Vestibular Evoked Myogenic Potentials : physiology, variability, and statistical characteristics  

E-print Network

Vestibular Evoked Myogenic Potentials (VEMPs) are electrical signals recorded from the skin overlying skeletal muscles of the head and neck in response to high-intensity acoustic stimuli. VEMPs have been observed in stimulus ...

Prakash, Srinivasamurthy Ravi

2009-01-01

294

Motion Perception in Patients with Idiopathic Bilateral Vestibular Hypofunction.  

PubMed

We measured vestibular perceptual thresholds in patients with idiopathic bilateral vestibulopathy to assess the distribution of peripheral vestibular damage in this disorder. Thresholds were measured with standard psychometric techniques in 4 patients and compared with thresholds in normal subjects and patients with completely absent peripheral vestibular function. Motion paradigms included yaw rotation (testing the lateral canals), interaural translation (testing the utricles), superior-inferior translation (testing the saccules), and roll tilt (testing the vertical semicircular canals and the otolith organs). We found that perceptual thresholds were abnormally elevated in the patients with idiopathic bilateral vestibulopathy for yaw rotation at all frequencies and for interaural translation at only the lower frequencies. Thresholds were normal for the other 2 motion paradigms. The results demonstrate that the distribution of vestibular dysfunction in this disorder is not uniform but, rather, can affect lateral canal and utricular thresholds while relatively sparing vertical canal and saccular function. PMID:24647642

Priesol, Adrian J; Valko, Yulia; Merfeld, Daniel M; Lewis, Richard F

2014-03-19

295

Payload specialist Wubbo Ockels prepares to use vestibular sled  

NASA Technical Reports Server (NTRS)

Payload specialist Wubbo J. Ockels prepares to lower the eye-gear portion of the vestibular sled helmet for a test on the busy sled. The scientist has sensors on his face and forehead for system monitoring.

1985-01-01

296

Surgical access to separate branches of the cat vestibular nerve  

NASA Technical Reports Server (NTRS)

A posteroventral approach for access to separate branches of the cat vestibular nerve is presented which permits simultaneous surgical access to the ampullary and otolithic nerves. Surgical procedures are discussed.

Radkevich, L. A.; Ayzikov, G. S.

1981-01-01

297

Optimal Stochastic Enhancement of Photoionization  

SciTech Connect

The effect of noise on the nonlinear photoionization of an atom due to a femtosecond pulse is investigated in the framework of the stochastic Schroedinger equation. A modest amount of white noise results in an enhancement of the net ionization yield by several orders of magnitude, giving rise to a form of quantum stochastic resonance. We demonstrate that this effect is preserved if the white noise is replaced by broadband chaotic light.

Singh, Kamal P.; Rost, Jan M. [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, D-01187 Dresden (Germany)

2007-04-20

298

Diversity of vestibular nuclei neurons targeted by cerebellar nodulus inhibition  

PubMed Central

Key points Electrical stimulation of the cerebellar nodulus and ventral uvula decreases the time constant of the horizontal vestibulo-ocular reflex during yaw rotation. Unlike the flocculus and ventral paraflocculus which target a particular cell group, nodulus/ventral uvula inhibition targets a large diversity of cell types in the vestibular nuclei. Twenty per cent of nodulus/ventral uvula-target neurons were sensitive to both vestibular stimuli and eye movements, whereas the majority was only sensitive to vestibular stimuli. Most nodulus/ventral uvula-target cells responded to both rotation and translation and only approximately half discriminated translational and gravitational accelerations. Projections of the nodulus/ventral uvula to both eye movement-and non-eye movement-sensitive vestibular nuclei neurons suggest a role in both eye movement generation and vestibulo-spinal or thalamo-cortical systems. Abstract?A functional role of the cerebellar nodulus and ventral uvula (lobules X and IXc,d of the vermis) for vestibular processing has been strongly suggested by direct reciprocal connections with the vestibular nuclei, as well as direct vestibular afferent inputs as mossy fibres. Here we have explored the types of neurons in the macaque vestibular nuclei targeted by nodulus/ventral uvula inhibition using orthodromic identification from the caudal vermis. We found that all nodulus-target neurons are tuned to vestibular stimuli, and most are insensitive to eye movements. Such non-eye-movement neurons are thought to project to vestibulo-spinal and/or thalamo-cortical pathways. Less than 20% of nodulus-target neurons were sensitive to eye movements, suggesting that the caudal vermis can also directly influence vestibulo-ocular pathways. In general, response properties of nodulus-target neurons were diverse, spanning the whole continuum previously described in the vestibular nuclei. Most nodulus-target cells responded to both rotation and translation stimuli and only a few were selectively tuned to translation motion only. Other neurons were sensitive to net linear acceleration, similar to otolith afferents. These results demonstrate that, unlike the flocculus and ventral paraflocculus which target a particular cell group, nodulus/ventral uvula inhibition targets a large diversity of cell types in the vestibular nuclei, consistent with a broad functional significance contributing to vestibulo-ocular, vestibulo-thalamic and vestibulo-spinal pathways. PMID:24127616

Meng, Hui; Blázquez, Pablo M; Dickman, J David; Angelaki, Dora E

2014-01-01

299

Effect of gravity on vestibular neural development  

NASA Technical Reports Server (NTRS)

The timing, molecular basis, and morphophysiological and behavioral consequences of the interaction between external environment and the internal genetic pool that shapes the nervous system over a lifetime remain important questions in basic neuroscientific research. Space station offers the opportunity to study this interaction over several life cycles in a variety of organisms. This short review considers past work in altered gravity, particularly on the vestibular system, as the basis for proposing future research on space station, and discusses the equipment necessary to achieve goals. It is stressed that, in keeping with the international investment being made in this research endeavor, both the questions asked and the technologies to be developed should be bold. Advantage must be taken of this unique research environment to expand the frontiers of neuroscience. Copyright 1998 Published by Elsevier Science B.V.

Ross, M. D.; Tomko, D. L.

1998-01-01

300

Clinical signs of visual-vestibular interaction.  

PubMed Central

Visual suppression of vestibulo-ocular reflexes (induced vestibular nystagmus) differs between normal subjects and patients with various neurological disorders. Abnormalities of VOR suppression were associated consistently with abnormalities of the visual and/or vesitibular oculomotor reflexes and in particular with abnormal smooth pursuit eye movements in the direction of abnormal suppression. Absent VOR suppression in a gaze position of, and in the same direction as, a spontaneous nystagmus was found exclusively in patients with spontaneous nystagmus of central nervous system origin. Conversely, ability to suppress in these circumstances was found only in patients with spontaneous nystagmus of peripheral labyrinthine origin. Suppression of VOR was abnormal ipsilaterally in patients with unilateral cerebral hemisphere lesions and abnormal in both the horizontal and vertical planes in patients with basal ganglia lesions. Failure of VOR suppression in the absence of spontaneous nystagmus indicates a supratentorial lesion. Images PMID:315999

Halmagyi, G M; Gresty, M A

1979-01-01

301

Intraoperative Monitoring and Facial Nerve Outcomes after Vestibular Schwannoma Resection  

Microsoft Academic Search

Objective: To determine the predictive value of proximal fa- cial nerve electrical threshold and proximal-to-distal facial muscle compound action potential amplitude ratio on facial nerve outcomes after resection of vestibular schwannomas. Study Design: Retrospective case review. Setting: Tertiary care hospital. Patients: Two hundred twenty-nine patients undergoing resec- tion of vestibular schwannomas with intraoperative facial nerve monitoring at a single institution.

Brandon Isaacson; Paul R. Kileny; Hussam El-Kashlan

2003-01-01

302

Early and Phasic Cortical Metabolic Changes in Vestibular Neuritis Onset  

PubMed Central

Functional brain activation studies described the presence of separate cortical areas responsible for central processing of peripheral vestibular information and reported their activation and interactions with other sensory modalities and the changes of this network associated to strategic peripheral or central vestibular lesions. It is already known that cortical changes induced by acute unilateral vestibular failure (UVF) are various and undergo variations over time, revealing different cortical involved areas at the onset and recovery from symptoms. The present study aimed at reporting the earliest change in cortical metabolic activity during a paradigmatic form of UVF such as vestibular neuritis (VN), that is, a purely peripheral lesion of the vestibular system, that offers the opportunity to study the cortical response to altered vestibular processing. This research reports [18F]fluorodeoxyglucose positron emission tomography brain scan data concerning the early cortical metabolic activity associated to symptoms onset in a group of eight patients suffering from VN. VN patients’ cortical metabolic activity during the first two days from symptoms onset was compared to that recorded one month later and to a control healthy group. Beside the known cortical response in the sensorimotor network associated to vestibular deafferentation, we show for the first time the involvement of Entorhinal (BAs 28, 34) and Temporal (BA 38) cortices in early phases of symptomatology onset. We interpret these findings as the cortical counterparts of the attempt to reorient oneself in space counteracting the vertigo symptom (Bas 28, 34) and of the emotional response to the new pathologic condition (BA 38) respectively. These interpretations were further supported by changes in patients’ subjective ratings in balance, anxiety, and depersonalization/derealization scores when tested at illness onset and one month later. The present findings contribute in expanding knowledge about early, fast-changing, and complex cortical responses to pathological vestibular unbalanced processing. PMID:23505435

Alessandrini, Marco; Pagani, Marco; Napolitano, Bianca; Micarelli, Alessandro; Candidi, Matteo; Bruno, Ernesto; Chiaravalloti, Agostino; Di Pietro, Barbara; Schillaci, Orazio

2013-01-01

303

[Vestibularly displaced flap with bone augmentation].  

PubMed

The aim of this study is to achieve esthetic gingival contours with the help of less traumatic mucogingival surgeries. 9 Patients were operated with horizontal deficiencies in 9 edentulous sites, planned to be restored with fixed partial dentures. In all cases there was lack of keratinized tissues. Temporary bridges were fabricated to all patients. Before surgery the bridges were removed and the abutment teeth were additionally cleaned with ultrasonic device. A horizontal incision was made from lingual (palatal) side between the abutment teeth, which was connected with two vertical releasing incisions to the mucogingival junction from the vestibular side. The horizontal incision was made on a distance 6-10 mm from the crest of the alveolar ridge. A partial thickness flap in the beginning 3-5 mm, then a full thickness flap up to the mucogingival junction, then a partial thickness flap was made. The flap was mobilized and displaced vestibularly. In the apical part the cortical bone was perforated, graft material was put and the flap was sutured. In all 9 cases the horizontal defect was partially or fully eliminated. The width of the keratinized tissues was also augmented in all cases. The postoperative healing was without complications, discomfort and painless. The donor sites also healed without complications. The application of Solcoseryl Dental Adhesive Paste 3 times a day for 7-10 days helped for painless healing of the donor site. The offered method of soft tissue and bone augmentation is effective in the treatment of horizontal defects of edentulous alveolar ridges of not big sizes. It makes possible to achieve esthetic results without traumatizing an additional donor-site. PMID:19644187

Bakalian, V L

2009-01-01

304

Vestibular adaptation to space in monkeys  

NASA Technical Reports Server (NTRS)

Otolith-induced eye movements of rhesus monkeys were studied before and after the 1989 COSMOS 2044 and the 1992 to 1993 COSMOS 2229 flights. Two animals flew in each mission for approximately 2 weeks. After flight, spatial orientation of the angular vestibulo-ocular reflex was altered. In one animal the time constant of postrotatory nystagmus, which had been shortened by head tilts with regard to gravity before flight, was unaffected by the same head tilts after flight. In another animal, eye velocity, which tended to align with a gravitational axis before flight, moved toward a body axis after flight. This shift of orientation disappeared by 7 days after landing. After flight, the magnitude of compensatory ocular counter-rolling was reduced by about 70% in both dynamic and static tilts. Modulation in vergence in response to naso-occipital linear acceleration during off-vertical axis rotation was reduced by more than 50%. These changes persisted for 11 days after recovery. An up and down asymmetry of vertical nystagmus was diminished for 7 days. Gains of the semicircular canal-induced horizontal and vertical angular vestibulo-ocular reflexes were unaffected in both flights, but the gain of the roll angular vestibulo-ocular reflex was decreased. These data indicate that there are short- and long-term changes in otolith-induced eye movements after adaptation to microgravity. These experiments also demonstrate the unique value of the monkey as a model for studying effects of vestibular adaptation in space. Eye movements can be measured in three dimensions in response to controlled vestibular and visual stimulation, and the results are directly applicable to human beings. Studies in monkeys to determine how otolith afferent input and central processing is altered by adaptation to microgravity should be an essential component of future space-related research.

Dai, M.; Raphan, T.; Kozlovskaya, I.; Cohen, B.

1998-01-01

305

Clinical features of intracranial vestibular schwannomas  

PubMed Central

The aim of the present study was to discuss the clinical features of intracranial vestibular schwannomas and to evaluate the symptoms and signs as well as their correlation with tumor extension. The records of 1,009 patients who were treated in Shanghai Huashan Hospital were reviewed retrospectively. According to the Samii classification of 1997, the patients were grouped into a T3 and a T4 group based on the radiological findings. We focused our analysis on the incidence of subjective disturbances versus objective morbidity, and symptomatology versus tumor size and extension. Of the 1,009 cases, 424 patients (42.0%) were defined as T3 while 585 patients (58%) were defined as T4. The most frequent clinical symptoms were hearing loss (85.8%), facial numbness (48.9%), ataxia (44.6%), tinnitus (40.1%), deafness (26.3%) and facial paralysis (21.1%). The ratios of gender, vertigo and facial paralysis were significantly different between the T3 and T4 groups (P<0.05); however, none of the clinical symptoms had a positive likelihood ratio (PLR) greater than 10 for T4 prediction. The most frequent cranial nerve disturbance was associated with the cochlear nerve (92.6%) and trigeminal nerve (53.5%). Disturbance of the facial nerve was more severe in T3 than T4 patients (P<0.05). Hearing deficit, facial paresthesia, ataxia and tinnitus are key symptoms of huge vestibular schwannomas. Cochlear, trigeminal and facial nerves were the most commonly affected cranial nerves in cases of large tumors. Gender and tumor size were associated with tumor extension. Although the predictive value was limited, the symptoms of vertigo, facial paralysis and hearing loss may be indicators of tumor growth. PMID:23255894

HUANG, XIANG; XU, JIAN; XU, MING; ZHOU, LIANG-FU; ZHANG, RONG; LANG, LIQIN; XU, QIWU; ZHONG, PING; CHEN, MINGYU; WANG, YING; ZHANG, ZHENYU

2013-01-01

306

Restoration of 3D vestibular sensation in rhesus monkeys using a multichannel vestibular prosthesis.  

PubMed

Profound bilateral loss of vestibular hair cell function can cause chronically disabling loss of balance and inability to maintain stable vision during head and body movements. We have previously shown that chinchillas rendered bilaterally vestibular-deficient via intratympanic administration of the ototoxic antibiotic gentamicin regain a more nearly normal 3-dimensional vestibulo-ocular reflex (3D VOR) when head motion information sensed by a head-mounted multichannel vestibular prosthesis (MVP) is encoded via rate-modulated pulsatile stimulation of vestibular nerve branches. Despite significant improvement versus the unaided condition, animals still exhibited some 3D VOR misalignment (i.e., the 3D axis of eye movement responses did not precisely align with the axis of head rotation), presumably due to current spread between a given ampullary nerve's stimulating electrode(s) and afferent fibers in non-targeted branches of the vestibular nerve. Assuming that effects of current spread depend on relative orientation and separation between nerve branches, anatomic differences between chinchilla and human labyrinths may limit the extent to which results in chinchillas accurately predict MVP performance in humans. In this report, we describe the MVP-evoked 3D VOR measured in alert rhesus monkeys, which have labyrinths that are larger than chinchillas and temporal bone anatomy more similar to humans. Electrodes were implanted in five monkeys treated with intratympanic gentamicin to bilaterally ablate vestibular hair cell mechanosensitivity. Eye movements mediated by the 3D VOR were recorded during passive sinusoidal (0.2-5 Hz, peak 50°/s) and acceleration-step (1000°/s(2) to 150°/s) whole-body rotations in darkness about each semicircular canal axis. During constant 100 pulse/s stimulation (i.e., MVP powered ON but set to stimulate each ampullary nerve at a constant mean baseline rate not modulated by head motion), 3D VOR responses to head rotation exhibited profoundly low gain [(mean eye velocity amplitude)/(mean head velocity amplitude) < 0.1] and large misalignment between ideal and actual eye movements. In contrast, motion-modulated sinusoidal MVP stimuli elicited a 3D VOR with gain 0.4-0.7 and axis misalignment of 21-38°, and responses to high-acceleration transient head rotations exhibited gain and asymmetry closer to those of unilaterally gentamicin-treated animals (i.e., with one intact labyrinth) than to bilaterally gentamicin-treated animals without MVP stimulation. In comparison to responses observed under similar conditions in chinchillas, acute responses to MVP stimulation in rhesus macaque monkeys were slightly better aligned to the desired rotation axis. Responses during combined rotation and prosthetic stimulation were greater than when either stimulus was presented alone, suggesting that the central nervous system uses MVP input in the context of multisensory integration. Considering the similarity in temporal bone anatomy and VOR performance between rhesus monkeys and humans, these observations suggest that an MVP will likely restore a useful level of vestibular sensation and gaze stabilization in humans. PMID:21888961

Dai, Chenkai; Fridman, Gene Y; Davidovics, Natan S; Chiang, Bryce; Ahn, Joong Ho; Della Santina, Charles C

2011-11-01

307

Vestibular findings associated with chronic noise induced hearing impairment.  

PubMed

Histological and functional derangements of the vestibular system have been reported in laboratory animals exposed to high levels of noise. However, clinical series describe contradictory results with regard to vestibular disturbances in industrial workers and military personnel suffering from noise induced hearing loss (NIHL). The purpose of the present study was to evaluate vestibular function in a group of subjects with documented NIHL, employing electronystagmography (ENG) and the smooth harmonic acceleration (SHA) test. Subjects were 22 men suffering from NIHL and 21 matched controls. Significantly lower vestibulo-ocular reflex gain (p = 0.05), and a tendency towards decreased caloric responses were found in the study group. No differences in the incidence of vertigo symptoms, spontaneous, positional and positioning nystagmus, directional preponderance and canal paresis in the ENG, or the SHA test phase and asymmetry parameters were observed between the groups. These results demonstrated a symmetrical centrally compensated decrease in the vestibular end organ response which is associated with the symmetrical hearing loss measured in the study group. Statistically significant correlations were found between the average hearing loss, the decrement in the average vestibulo-ocular reflex gain (p = 0.01), and ENG caloric lateralization (p = 0.02). These correlations might indicate a single mechanism for both cochlear and vestibular noise-induced injury. The results imply subclinical, well compensated malfunction of the vestibular system associated with NIHL. PMID:7879613

Shupak, A; Bar-El, E; Podoshin, L; Spitzer, O; Gordon, C R; Ben-David, J

1994-11-01

308

Patterning of sympathetic nerve activity in response to vestibular stimulation  

NASA Technical Reports Server (NTRS)

Growing evidence suggests a role for the vestibular system in regulation of autonomic outflow during postural adjustments. In the present paper we review evidence for the patterning of sympathetic nerve activity elicited by vestibular stimulation. In response to electrical activation of vestibular afferents, firing of sympathetic nerves located throughout the body is altered. However, activity of the renal nerve is most sensitive to vestibular inputs. In contrast, high-intensity simultaneous activation of cutaneous and muscle inputs elicits equivalent changes in firing of the renal, superior mesenteric and lumbar colonic nerves. Responses of muscle vasoconstrictor (MVC) efferents to vestibular stimulation are either inhibitory (Type I) or are comprised of a combination of excitation and inhibition (Type II). Interestingly, single MVC units located in the hindlimb exhibited predominantly Type I responses while those located in the forelimb and face exhibited Type II responses. Furthermore, brachial and femoral arterial blood flows were dissociated in response to vestibular stimulation, such that brachial vascular resistance increased while femoral resistance decreased. These studies demonstrate that vestibulosympathetic reflexes are patterned according to both the anatomical location and innervation target of a particular sympathetic nerve, and can lead to distinct changes in local blood flow.

Kerman, I. A.; McAllen, R. M.; Yates, B. J.

2000-01-01

309

How the vestibular system interacts with somatosensory perception: A sham-controlled study with galvanic vestibular stimulation  

PubMed Central

The vestibular system has widespread interactions with other sensory modalities. Here we investigate whether vestibular stimulation modulates somatosensory function, by assessing the ability to detect faint tactile stimuli to the fingertips of the left and right hand with or without galvanic vestibular stimulation (GVS). We found that left anodal and right cathodal GVS, significantly enhanced sensitivity to mild shocks on either hand, without affecting response bias. There was no such effect with either right anodal and left cathodal GVS or sham stimulation. Further, the enhancement of somatosensory sensitivity following GVS does not strongly depend on the duration of GVS, or the interval between GVS and tactile stimulation. Vestibular inputs reach the somatosensory cortex, increasing the sensitivity of perceptual circuitry. PMID:23827220

Ferrč, Elisa R.; Day, Brian L.; Bottini, Gabriella; Haggard, Patrick

2013-01-01

310

Virtual labyrinth model of vestibular afferent excitation via implanted electrodes: validation and application to design of a multichannel vestibular prosthesis  

Microsoft Academic Search

To facilitate design of a multichannel vestibular prosthesis that can restore sensation to individuals with bilateral loss\\u000a of vestibular hair cell function, we created a virtual labyrinth model. Model geometry was generated through 3-dimensional (3D) reconstruction of microMRI and microCT scans of normal chinchillas\\u000a (Chinchilla lanigera) acquired with 30–48 ?m and 12 ?m voxels, respectively. Virtual electrodes were positioned based on anatomic

Russell Hayden; Stacia Sawyer; Eric Frey; Susumu Mori; Americo A. Migliaccio; Charles C. Della Santina

2011-01-01

311

Current treatment of nasal vestibular stenosis with CO2-laser surgery: prolonged vestibular stenting versus intraoperative mitomycin application. A case series of 3 patients.  

PubMed

These case studies describe three cases of unilateral nasal vestibular stenoses caused by chemical cauterization. Each case was treated with CO2-laser surgery together with intraoperative topic application of mitomycin or prolonged vestibular stenting for prevention of restenosis. Two patients received intraoperative mitomycin application and one patient received prolonged vestibular stenting. Results were documented using high-resolution photographs. The follow up period ranged from 1 year and 3 months to 4 years and 9 months. All patients improved after CO2-laser surgery. No complications were reported. We consider CO2-laser surgery for relief of nasal vestibular stenosis as a feasible surgical technique for relieve of nasal vestibular stenosis. Prolonged vestibular stenting seems to be an important factor for the prevention of restenosis in which the value of intraoperative mitomycin application without prolonged vestibular stenting remains uncertain. PMID:25282303

van Schijndel, Olaf; van Heerbeek, Niels; Ingels, Koen J A O

2014-12-01

312

Role of vestibular information in initiation of rapid postural responses  

NASA Technical Reports Server (NTRS)

Patients with bilateral vestibular loss have difficulty maintaining balance without stepping when standing in tandem, on compliant surfaces, across narrow beams, or on one foot, especially with eyes closed. Normal individuals (with no sensory impairment) maintain balance in these tasks by employing quick, active hip rotation (a "hip strategy"). The absence of a hip strategy in vestibular patients responding to translations of a short support surface has previously been taken as evidence that the use of hip strategy requires an intact vestibular system. However, many tasks requiring hip strategy alter one or a combination of important system characteristics, such as initial state of the body (tandem stance), dynamics (compliant surfaces), or biomechanical limits of stability (narrow beams). Therefore, the balance deficit in these tasks may result from a failure to account for these support surface alterations when planning and executing sensorimotor responses. In this study, we tested the hypothesis that vestibular information is critical to trigger a hip strategy even on an unaltered support surface, which imposes no changes on the system characteristics. We recorded the postural responses of vestibular patients and control subjects with eyes closed to rearward support surface translations of varying velocity, in erect stance on a firm, flat surface. Subjects were instructed to maintain balance without stepping, if possible. Faster translation velocities (25 cm/s or more) produced a consistent pattern of early hip torque (first 400 ms) in control subjects (i.e., a hip strategy). Most of the patients with bilateral vestibular loss responded to the same translation velocities with similar torques. Contrary to our hypothesis, we conclude that vestibular function is not necessary to trigger a hip strategy. We postulate, therefore, that the balance deficit previously observed in vestibular patients during postural tasks that elicit a hip strategy may have been due to the sensorimotor consequences of the system alterations imposed by the postural tasks used in those studies. Preliminary results from two younger patients who lost vestibular function as infants indicate that age, duration of vestibular loss, and/or the timing of the loss may also be factors that can influence the use of hip strategy as a rapid postural response.

Runge, C. F.; Shupert, C. L.; Horak, F. B.; Zajac, F. E.; Peterson, B. W. (Principal Investigator)

1998-01-01

313

Stochastic Modeling of Laminar-Turbulent Transition  

NASA Technical Reports Server (NTRS)

Stochastic versions of stability equations are developed in order to develop integrated models of transition and turbulence and to understand the effects of uncertain initial conditions on disturbance growth. Stochastic forms of the resonant triad equations, a high Reynolds number asymptotic theory, and the parabolized stability equations are developed.

Rubinstein, Robert; Choudhari, Meelan

2002-01-01

314

Stochastic Resonance (365) Samuel Herrmann  

E-print Network

volume of ice. The second part of the outgoing radiation comes from the fact that the Earth radiates time series confining glacial cycles. Data collected for instance from ice or deep sea cores allow switching between ice and warm ages with fast spontaneous transitions. The average periodicity

315

Vestibular rehabilitation ameliorates chronic dizziness through the SIRT1 axis  

PubMed Central

Dizziness is a common clinical symptom frequently referred to general neurologists and practitioners. Exercise intervention, in the form of vestibular rehabilitation, is known as an effective clinical management for dizziness. This intervention is reported to have a functional role in correcting dizziness, improving gaze stability, retraining balance and gait, and enhancing physical fitness. Dizziness is known to be highly related to inflammation and oxidative stress. SIRT1 is a major molecule for the regulation of inflammation and mitigation of oxidative stress in chronic diseases such as atherosclerosis and chronic obstructive pulmonary disease. However, the bio-molecular roles of SIRT1 involved in the pathogenesis of dizziness are still largely unclear. In this study, a total of 30 subjects were recruited (15 patients with chronic dizziness, and 15 age/gender matched non-dizzy control subjects). The dizzy subjects group received 18 sessions of 30-min vestibular training. We found that the mRNA and protein expression levels of SIRT1 in the blood samples of chronic dizzy patients were repressed compared with those of healthy controls. After vestibular training, the dizzy patients had significant symptomatic improvements. The SIRT1 expression and its downstream genes (PPAR-? and PGC-1?) were upregulated after vestibular exercises in dizzy subjects. Notably, the catalytic activity of SIRT1, NADPH and antioxidant enzyme activities were also activated in dizzy patients after vestibular training. Furthermore, vestibular exercise training reduced oxidative events and p53 expression in patients with dizziness. This study demonstrated that vestibular exercise training improved dizziness symptoms, and mechanisms for alleviation of chronic dizziness may partly involve the activation of the SIRT1 axis and the repression of redox status. PMID:24624081

Kao, Chung-Lan; Tsai, Kun-Ling; Cheng, Yuan-Yang; Kuo, Chia-Hua; Lee, Shin-Da; Chan, Rai-Chi

2014-01-01

316

Genetics of Peripheral Vestibular Dysfunction: Lessons from Mutant Mouse Strains  

PubMed Central

Background A considerable amount of research has been published about genetic hearing impairment. Fifty to sixty percent of hearing loss is thought to have a genetic cause. Genes may also play a significant role in acquired hearing loss due to aging, noise exposure, or ototoxic medications. Between 1995 and 2012, over 100 causative genes have been identified for syndromic and nonsyndromic forms of hereditary hearing loss (see Hereditary Hearing Loss Homepage http://hereditaryhearingloss.org). Mouse models have been extremely valuable in facilitating the discovery of hearing loss genes, and in understanding inner ear pathology due to genetic mutations or elucidating fundamental mechanisms of inner ear development. Purpose Whereas much is being learned about hereditary hearing loss and the genetics of cochlear disorders, relatively little is known about the role genes may play in peripheral vestibular impairment. Here we review the literature with regard to genetics of vestibular dysfunction and discuss what we have learned from studies using mutant mouse models and direct measures of peripheral vestibular neural function. Results Several genes are considered that when mutated lead to varying degrees of inner ear vestibular dysfunction due to deficits in otoconia, stereocilia, hair cells, or neurons. Behavior often does not reveal the inner ear deficit. Many of the examples presented are also known to cause human disorders. Conclusions Knowledge regarding the roles of particular genes in the operation of the vestibular sensory apparatus is growing and it is clear that gene products co-expressed in the cochlea and vestibule may play different roles in the respective end organs. The discovery of new genes mediating critical inner ear vestibular function carries the promise of new strategies in diagnosing, treating and managing patients as well as predicting the course and level of morbidity in human vestibular disease. PMID:25032973

Jones, Sherri M.; Jones, Timothy A.

2015-01-01

317

Fifth Symposium on the Role of the Vestibular Organs in Space Exploration  

NASA Technical Reports Server (NTRS)

Vestibular problems of manned space flight are investigated for weightlessness and reduced gravity conditions with emphasis on space station development. Intensive morphological studies on the vestibular system and its central nervous system connections are included.

1973-01-01

318

Effects of microgravity on vestibular ontogeny: direct physiological and anatomical measurements following space flight (STS-29)  

NASA Technical Reports Server (NTRS)

Does space flight change gravity receptor development? The present study measured vestibular form and function in birds flown as embryos for 5 days in earth orbit (STS-29). No major changes in vestibular gross morphology were found. Vestibular response mean amplitudes and latencies were unaffected by space flight. However, the results of measuring vestibular thresholds were mixed and abnormal responses in 3 of the 8 flight animals raise important questions.

Jones, T. A.; Fermin, C.; Hester, P. Y.; Vellinger, J.

1993-01-01

319

Impaired navigation skills in patients with psychological distress and chronic peripheral vestibular hypofunction without vertigo.  

PubMed

Few studies have focused on the role of the vestibular system for navigation and spatial memory functions in humans, with controversial results. Since most experimental settings were based on magnetic resonance imaging volumetry of the hippocampus and virtual navigation task on a PC, aim of this study was to investigate whether a well-compensated unilateral peripheral vestibular hypofunction in humans could interfere with navigation tasks while walking on memorized routes. A series of 50 unilateral labyrinthine-defective patients, without vertigo at the time of examination, and 50 controls were invited to visually memorize 3 different routes (a triangle, a circle and a square) on a grey carpet and then to walk along them clockwise and counter-clockwise (mental map navigation) with eyes closed. The same test was then repeated with eyes open (actual navigation) and a second time with eyes closed (mental navigation). Execution time was recorded in each test. In the same session, working spatial memory was assessed by the Corsi block test and all subjects completed the Symptom Check List (SCL-90) to assess depression and anxiety levels. Results showed that labyrinthine-defective patients presented higher levels of anxiety and depression and performed the Corsi block test with more difficulties than controls. All differences reached statistically significant level (p < 0.05). Moreover, patients needed more time than controls in the first and third navigation tasks (eyes closed). No difference was observed between clockwise and counter-clockwise walking, on all routes, either in patients or controls. Patients showed a greater improvement in the third navigation task, with respect to the first test, than controls, with no side-effect in relation to labyrinthine hypofunction. These data demonstrate that walking along memorized routes without vision is impaired by peripheral vestibular damage even if vestibular compensation prevents patients from suffering from vertigo and balance disturbances. This impairment could be due to a permanent deficit of visuo-spatial short-term memory as suggested by the Corsi block test results even if a residual sensori-motor impairment and/or an interference of psychological distress could not be excluded. PMID:18533551

Guidetti, G; Monzani, D; Trebbi, M; Rovatti, V

2008-02-01

320

Ocular vestibular evoked myogenic potential frequency tuning in certain Meničre's disease.  

PubMed

Ocular vestibular evoked myogenic potentials (oVEMP) represent extraocular muscle activity in response to vestibular stimulation. To specify the value of oVEMP in the diagnostics of Meničre's disease, the amplitude ratio between 500 and 1000 Hz stimuli was investigated. Thirty-nine patients with certain Meničre's disease, i.e. definite Meničre's disease with visualization of endolymphatic hydrops by magnetic resonance imaging and 19 age-matched healthy controls were enrolled in this study. oVEMP were recorded using 500 and 1000 Hz air-conducted tone bursts. For Meničre's ears, the 500/1000 Hz amplitude ratio (mean ratio = 1.20) was significantly smaller when compared to unaffected ears of Meničre's patients (mean ratio = 1.80; p = 0.008) or healthy controls (mean ratio = 1.81; p = 0.011). The amplitude ratio was neither correlated with the degree of endolymphatic hydrops nor with the duration of disease. While an older age was associated with a diminished amplitude ratio in healthy controls, there was no correlation between the amplitude ratio and age in Meničre's ears. Hence, the calculation of the oVEMP 500/1000 Hz amplitude ratio may be a valuable diagnostic tool for Meničre's disease. PMID:24530828

Jerin, Claudia; Berman, Albert; Krause, Eike; Ertl-Wagner, Birgit; Gürkov, Robert

2014-04-01

321

Sensitivity of human visual and vestibular cortical regions to egomotion-compatible visual stimulation.  

PubMed

The analysis and representation of visual cues to self-motion (egomotion) is primarily associated with cortical areas MST, VIP, and (recently) cingulate sulcus visual area (CSv). Various other areas, including visual areas V6 and V6A, and vestibular areas parietoinsular vestibular cortex (PIVC), putative area 2v (p2v), and 3aNv, are also potentially suited to processing egomotion (in some cases based on multisensory cues), but it is not known whether they are in fact involved in this process. In a functional magnetic resonance imaging (fMRI) experiment, we presented human participants with 2 types of random dot kinematograms. Both contained coherent motion but one simulated egomotion while the other did not. An area in the parieto-occipital sulcus that may correspond to V6, PIVC, and p2v were all differentially responsive to egomotion-compatible visual stimuli, suggesting that they may be involved in encoding egomotion. More generally, we show that the use of such stimuli provides a simple and reliable fMRI localizer for human PIVC and p2v, which hitherto required galvanic or caloric stimulation to be identified. PMID:20034998

Cardin, Velia; Smith, Andrew T

2010-08-01

322

Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) - a case report and review of literature.  

PubMed

CANVAS (cerebellar ataxia with neuropathy and vestibular areflexia syndrome) is a rare neurological syndrome of unknown etiology. The main clinical features include bilateral vestibulopathy, cerebellar ataxia and sensory neuropathy. An abnormal visually enhanced vestibulo-ocular reflex is the hallmark of the disease. We present a case of 58-year-old male patient who has demonstrated gait disturbance, imbalance and paresthesia of feet for 2 years. On examination ataxia of gait, diminished knee and ankle reflexes, absence of plantar reflexes, fasciculations of thigh muscles, gaze-evoked downbeat nystagmus and abnormal visually enhanced vestibulo-ocular reflex were found. Brain magnetic resonance imaging revealed cerebellar atrophy. Vestibular function testing showed severely reduced horizontal nystagmus in response to bithermal caloric stimulation. Nerve conduction study revealed loss of upper and lower limb sensory nerve action potentials. The course of illness was progressive with ataxic gait and unsteadiness as the most disabling symptoms. We report 4-year follow-up of the patient since the beginning of the disease. PMID:25440017

Figura, Monika; Gawe?, Ma?gorzata; Kolasa, Anna; Janik, Piotr

2014-01-01

323

Abstract. With galvanic vestibular stimulation (GVS), electrical current is delivered transcutaneously to the  

E-print Network

Abstract. With galvanic vestibular stimulation (GVS), electrical current is delivered, including the vestibular system. With galvanic vestibular stimulation (GVS), electrical current is delivered in dierent directions depending on the polarity of the current. Our objective in this study was to test

Collins, James J.

324

Otolith-Canal Convergence In Vestibular Nuclei Neurons  

NASA Technical Reports Server (NTRS)

The current final report covers the period from June 1, 1999 to May 31, 2002. The primary objective of the investigation was to determine how information regarding head movements and head position relative to gravity is received and processed by central vestibular nuclei neurons in the brainstem. Specialized receptors in the vestibular labyrinths of the inner ear function to detect angular and linear accelerations of the head, with receptors located in the semicircular canals transducing rotational head movements and receptors located in the otolith organs transducing changes in head position relative to gravity or linear accelerations of the head. The information from these different receptors is then transmitted to central vestibular nuclei neurons which process the input signals, then project the appropriate output information to the eye, head, and body musculature motor neurons to control compensatory reflexes. Although a number of studies have reported on the responsiveness of vestibular nuclei neurons, it has not yet been possible to determine precisely how these cells combine the information from the different angular and linear acceleration receptors into a correct neural output signal. In the present project, rotational and linear motion stimuli were separately delivered while recording responses from vestibular nuclei neurons that were characterized according to direct input from the labyrinth and eye movement sensitivity. Responses from neurons receiving convergent input from the semicircular canals and otolith organs were quantified and compared to non-convergent neurons.

Dickman, J. David; Si, Xiao-Hong

2002-01-01

325

Isolated floccular infarction: impaired vestibular responses to horizontal head impulse.  

PubMed

Isolated floccular infarction is extremely rare, and impairments of the vestibulo-ocular reflex (VOR) have not been explored in humans with isolated floccular lesions. The purpose of this study was to examine and report selective impairment of VOR in response to high acceleration using head impulse in a patient with isolated floccular infarction. The patient underwent bedside and laboratory evaluation of vestibular function, which included video-oculography, ocular torsion and the subjective visual vertical, cervical and ocular vestibular-evoked myogenic potentials, bithermal caloric irrigation, rotatory chair test, and the head impulse test (HIT) using search coils. A 70-year-old woman with a unilateral floccular infarction presented with an acute vestibular syndrome with spontaneous nystagmus beating to the lesion side, impaired ipsilesional pursuit, contraversive ocular torsion and tilt of the subjective visual vertical. With rotatory chair testing at low frequencies, horizontal VOR gains were increased. However, VOR gains were decreased with the higher-frequency, higher-speed HIT. While HIT is often normal in patients with central vestibular disorders, decreased HIT responses do not exclude an isolated cerebellar lesion as a cause of the acute vestibular syndrome. PMID:23370610

Park, Hong-Kyun; Kim, Ji-Soo; Strupp, Michael; Zee, David S

2013-06-01

326

Large vestibular aqueduct syndrome: a case study.  

PubMed

A 23-month-old female was referred for hearing aid fitting after failing newborn hearing screening and being diagnosed with significant hearing loss through subsequent diagnostic testing. Auditory brainstem response (ABR) and behavioral testing revealed a moderate-to-severe bilateral mixed hearing loss. Prior to the hearing aid evaluation, tympanostomy tubes had been placed bilaterally with little or no apparent change in hearing sensitivity. Initial testing during the hearing aid fitting confirmed earlier findings, but abnormal middle ear results were observed, requiring referral for additional otologic management. Following medical clearance, binaural digital programmable hearing aids were fit using Desired Sensation Level parameters. Behavioral testing and probe microphone measures showed significant improvements in audibility. Decrease in hearing sensitivity was observed six months following hearing aid fitting. Radiological studies, ordered due to the mixed component and decreased hearing sensitivity, revealed large vestibular aqueduct syndrome (LVAS). Based on the diagnosis of LVAS, a cochlear implant was placed on the right ear; almost immediate speech-language gains were observed. PMID:16515134

Clark, Jackie L; Roeser, Ross J

2005-01-01

327

Vestibular testing in basilar artery migraine.  

PubMed

Vestibular function studies were performed in 20 children with symptoms suggesting basilar artery migraine. Sixteen children had abnormalities on bithermal caloric testing. Labyrinthine preponderance was found in 1 child with labyrinthine concussion and in 6 children with symptoms suggesting ischemia of the territory supplied by the basilar artery and the occipital branches of the posterior cerebral arteries. Directional preponderance was found in 4 children with symptoms suggesting ischemia of the posterior temporal branches of the posterior cerebral arteries. Five children had both labyrinthine and directional preponderance. normal electronystagmographic findings were present in 4 children and correlated clinically with a milder illness. Head trauma was the triggering factor for the migraine in 5 children. Five children developed complex partial seizures and had evidence of directional preponderance (2 children) and combined labyrinthine and directional preponderance (2 children). The presence of abnormalities on electronystagmography in children with basilar artery migraine correlates with the severity of the disease. Directional preponderance or labyrinthine and directional preponderance are more frequently correlated with ischemia in the posterior temporal branches of the posterior cerebral arteries and may suggest a higher risk of developing vertiginous seizures when ischemia is prolonged. PMID:7235628

Eviatar, L

1981-02-01

328

Stochastic model of the residual acceleration environment in microgravity  

NASA Technical Reports Server (NTRS)

We describe a theoretical investigation of the effects that stochastic residual accelerations (g-jitter) onboard spacecraft can have on experiments conducted in a microgravity environment. We first introduce a stochastic model of the residual acceleration field, and develop a numerical algorithm to solve the equations governing fluid flow that allow for a stochastic body force. We next summarize our studies of two generic situations: stochastic parametric resonance and the onset of convective flow induced by a fluctuating acceleration field.

Vinals, Jorge

1994-01-01

329

A real-time research platform to study vestibular implants with gyroscopic inputs in vestibular deficient subjects.  

PubMed

Researchers have succeeded in partly restoring damaged vestibular functionality in several animal models. Recently, acute interventions have also been demonstrated in human patients. Our previous work on a vestibular implant for humans used predefined stimulation patterns; here we present a research tool that facilitates motion-modulated stimulation. This requires a system that can process gyroscope measurements and send stimulation parameters to a hybrid vestibular-cochlear implant in real-time. To match natural vestibular latencies, the time from sensor input to stimulation output should not exceed 6.5 ms. We describe a system based on National Instrument's CompactRIO platform that can meet this requirement and also offers floating point precision for advanced transfer functions. It is designed for acute clinical interventions, and is sufficiently powerful and flexible to serve as a development platform for evaluating prosthetic control strategies. Amplitude and pulse frequency modulation to predetermined functions or sensor inputs have been validated. The system has been connected to human patients, who each have received a modified MED-EL cochlear implant for vestibular stimulation, and patient tests are ongoing. PMID:25073124

Nguyen, T A Khoa; Ranieri, Maurizio; DiGiovanna, Jack; Peter, Otto; Genovese, Vincenzo; Perez Fornos, Angelica; Micera, Silvestro

2014-08-01

330

IEEE SENSORS JOURNAL, VOL. 12, NO. 4, APRIL 2012 785 1.1 TMACS/mW Fine-Grained Stochastic Resonant  

E-print Network

-domain analog accumulation. A stochastic data modulation scheme minimizes on-chip capacitance vari- ability it for publication was Dr. Alexander Fish. R. Karakiewicz was with the Department of Electrical and Computer Engi.2113393 Analog or mixed-signal VLSI signal processing often allows for increases in integration density

Genov, Roman

331

A model analysis of static stress in the vestibular membranes  

PubMed Central

Background The scheme of the core vestibular membranes, consisting of serially connected utricle, ampulla and semicircular canal, first appeared hundreds of millions of years ago in primitive fish and has remained largely unchanged during the subsequent course of evolution. The labyrinths of higher organisms build on this core structure, with the addition of the phylogenetically newer membrane structures, namely, saccule, lagena and cochlea. An analysis of static stress in these core vestibular membranes may contribute to a better understanding of the role of stress in the evolution of derivative membrane structures over the long term as well as the short-term membrane distortions seen in Meniere's disease. Methods A model of these core vestibular membranes is proposed in order to analyze the distribution of stress in the walls of the component chambers. The model uses basic geometrical elements of hollow cylinders and spheres to emulate the actual structures. These model elements lend themselves to a mathematical analysis of static stress in their membranes. Results Hoop stress, akin to the stress in hoops used to reinforce barrel walls, is found to be the predominant stress in the model membranes. The level of hoop stress depends not only on pressure but as well on a geometric stress factor that incorporates membrane shape, thickness and curvature. This result implies that hoop stress may be unevenly distributed in the membranes of the several vestibular chambers due to variations in these dimensional parameters. These results provide a theoretical framework for appraising hoop stress levels in any vestibular labyrinth whose dimensions are known. Conclusion Static hoop stress disparities are likely to exist in the vestibular membranes given their complex physical configurations. Such stress disparities may contribute to the development of membrane pathologies as seen in Meniere's Disease. They may also factor in the evolutionary development of other derivative membrane structures such as the saccule, the lagena, and the cochlea found in higher animals. PMID:19723316

Pender, Daniel J

2009-01-01

332

Short latency vestibular evoked potentials in the chicken embryo  

NASA Technical Reports Server (NTRS)

Electrophysiological responses to pulsed linear acceleration stimuli were recorded in chicken embryos incubated for 19 or 20 days (E19/E20). Responses occurred within the first 16 ms following the stimulus onset. The evoked potentials disappeared following bilateral labyrinthectomy, but persisted following cochlear destruction alone, thus demonstrating that the responses were vestibular. Approximately 8 to 10 response peaks could be identified. The first 4 positive and corresponding negative components (early peaks with latencies < 6.0 ms) were scored and latencies and amplitudes quantified. Vestibular response latencies were significantly longer (P < 0.01) and amplitudes significantly smaller (P < 0.001) than those observed in 2-week-old birds. Mean response threshold for anesthetized embryos was -15.9dBre 1.0 g/ms, which was significantly higher (P < 0.03) than those observed in 2-week-old birds (-23.0dBre 1.0 g/ms). Latency/intensity functions (that is, slopes) were not significantly different between embryos and 2-week-old animals, but amplitude/intensity functions for embryos were significantly shallower than those for 2-week-old birds (P < 0.001). We presume that these differences reflect the refinement of sensory function that occurs following 19 to 20 days of incubation. The recording of vestibular evoked potentials provides an objective, direct and noninvasive measure of peripheral vestibular function in the embryo and, as such, the method shows promise as an investigative tool. The results of the present study form the definitive basis for using vestibular evoked potentials in the detailed study of avian vestibular ontogeny and factors that may influence it.

Jones, S. M.; Jones, T. A.

1996-01-01

333

Interrelated striated elements in vestibular hair cells of the rat  

NASA Technical Reports Server (NTRS)

A series of interrelated striated organelles in types I and II vestibular hair cells of the rat which appear to be less developed in cochlear hair cells have been revealed by unusual fixation procedures, suggesting that contractile elements may play a role in sensory transduction in the inner ear, especially in the vestibular system. Included in the series of interrelated striated elements are the cuticular plate and its basal attachments to the hair cell margins, the connections of the strut array of the kinociliary basal body to the cuticular plate, and striated organelles associated with the plasma membrane and extending below the apical junctional complexes.

Ross, M. D.; Bourne, C.

1983-01-01

334

Asymmetric vestibular evoked myogenic potentials in unilateral Meničre patients  

PubMed Central

Vestibular evoked myogenic potentials (VEMPs) were measured in 22 unilateral Meničre patients with monaural and binaural stimulation with 250 and 500 Hz tone bursts. For all measurement situations significantly lower VEMP amplitudes were on average measured at the affected side compared to the unaffected side. Unilateral Meničre patients have, in contrast to normal subjects, asymmetric VEMPs, indicating a permanently affected vestibular (most likely otolith) system at the side of hearing loss. The diagnostic value of VEMP amplitude asymmetry measurement in individual patients is low, because of the large overlap of the VEMP amplitude asymmetry range for unilateral Meničre patients with that for normal subjects. PMID:20665043

Wit, H. P.

2010-01-01

335

A Case of Psychogenic Dizziness Mimicking Vestibular Epilepsy  

PubMed Central

A 28-year-old patient presented with frequent episodes of clockwise whirling vertigo, with no ear symptoms or anxiety. He had a previous history of encephaloduroarteriosynangiosis from Moyamoya disease 3 years ago. We assumed that the ictus was a manifestation of vestibular epilepsy. Although the patient was monitored continuously with video and computerized electroencephalography equipment for 24 hours, his vertigo was not accompanied by electroencephalographic discharges. And thorough vestibular evaluation was normal. His symptom was alleviated by psychological support. Psychogenic dizziness may also manifest as recurrent whirling vertigo with unilateral directionality. PMID:24649463

Lee, Kyung Jae; Jeong, Seong-Hae; Baek, In Chul; Lee, Ae Young; Kim, Jae-Moon

2012-01-01

336

Comparison of symptoms and laboratory findings in unilateral vestibular dysfunction.  

PubMed

Although vertigo is the expected symptom of unilateral vestibular disease, exceptions have been observed. To determine the relative frequency of this observation, a retrospective study of patients seen over a 1-year period was done. Of the 126 patients found to have unilateral labyrinthine impairment with bithermal caloric testing, only 58 (46%) characterized their symptoms as vertigo. The ramifications of these findings are discussed, and a question is raised as to the propriety of reserving vestibular testing for only those patients describing vertigo. PMID:6438589

Keim, R J

1984-10-01

337

Click-evoked vestibular activation in the Tullio phenomenon.  

PubMed Central

Click-evoked vestibulocollic reflexes were studied in a patient with a unilateral Tullio phenomenon (sound induced vestibular symptoms) and the findings were compared with those of a group of normal subjects. Compared with normal subjects, the reflexes elicited from her symptomatic side were large and had an abnormally low threshold, but retained a normal waveform. The click-evoked responses in this patient show changes consistent with her symptomatology and are indicative of a pathological increase in the normal vestibular sensitivity to sound. PMID:7798988

Colebatch, J G; Rothwell, J C; Bronstein, A; Ludman, H

1994-01-01

338

Neurohumoral reactions to long-term vestibular stimulation in man.  

PubMed

The main purposes of present work were: 1) to examine neurohumoral reactions to long-term vestibular stimulation provocative for MS symptoms in man; 2) to compare the peculiarities of neuroendocrine reactions to short-term and to long-term vestibular stimulation; 3) to analyze the received results from the position of neuroendocrine adaptive reactions biological conformity to natural laws, and its physiological importance for human organisms; 4) to make some prognostic points of neurohumoral reaction changes on health and capacity for work in subjects influenced by professional conditions, provocative for MS manifestation development. PMID:11538529

Nichiporuk, I A; Rapotkov, A N; Orlov, O I; Grigoriev, A I

1993-02-01

339

Use of the Vestibular Disorders Activities of Daily Living Scale to describe functional limitations in patients with vestibular disorders.  

PubMed

The Vestibular Disorders Activities of Daily Living Scale (VADL) is one of several self-rated scales in the literature that may be useful for determining level of functional limitation or disability in people with vestibular disorders. The VADL was designed by an occupational therapist for use in treatment planning during vestibular rehabilitation. Unlike many other scales the VADL is specifically focused on essential functional skills and important mobility and instrumental skills. This paper reviews the findings about the VADL, including the original research about its development and more recent papers using it. The scale is most useful for assessing the patient's perception about independence in personal, self care and basic mobility skills. It provides an outline for discussing instrumental activities of daily living. PMID:24594498

Cohen, Helen S

2014-01-01

340

Polyamines in the lateral vestibular nuclei of the squirrel monkey and their potential role in vestibular compensation  

NASA Technical Reports Server (NTRS)

Polyamine synthesis increases in response to injurious stimuli including axotomy and denervation. Reduced eye nystagmus and head-deviation have been observed in unilateral labyrinthectomized (UL) guinea pigs treated with an inhibitor of polyamine synthesis, alpha-difluoromethylornithine (DFMO). We quantified polyamines in the lateral vestibular nuclei (LVN) of control and UL squirrel monkeys during the phase of vestibular compensation (VC) and performed an experiment to determine if DFMO reduces nystagmus previously observed in the guinea pig. Polyamines were detected in the LVN of control and UL squirrel monkeys. Putrescine and spermidine increased in the ipsilateral LVN 3 days after UL with no change in the contralateral LVN. No left-right differences were noted in the 5-day post-UL monkey. DFMO reduced nystagmus in a UL squirrel monkey. These findings suggest that polyamines are important in vestibular function and may contribute to nystagmus observed in VC.

Henley, C.; Igarashi, M.

1993-01-01

341

The Role of Cervical and Ocular Vestibular Evoked Myogenic Potentials in the Assessment of Patients with Vestibular Schwannomas  

PubMed Central

Objectives To investigate the clinical utility of VEMPs in patients suffering from unilateral vestibular schwannoma (VS) and to determine the optimal stimulation parameter (air conducted sound, bone conducted vibration) for evaluating the function of the vestibular nerve. Methods Data were obtained in 63 patients with non-operated VS, and 20 patients operated on VS. Vestibular function was assessed by caloric, cervical and ocular VEMP testing. 37/63 patients with conclusive ACS ocular VEMPs responses were studied separately. Results In the 63 non-operated VS patients, cVEMPs were abnormal in 65.1% of patients in response to AC STB and in 49.2% of patients to AC clicks. In the 37/63 patients with positive responses from the unaffected side, oVEMPs were abnormal in 75.7% of patients with ACS, in 67.6% with AFz and in 56.8% with mastoid BCV stimulation. In 16% of the patients, VEMPs were the only abnormal test (normal caloric and normal hearing). Among the 26 patients who did not show oVEMP responses on either side with ACS, oVEMPs responses could be obtained with AFz (50%) and with mastoid stimulation (89%). Conclusions The VEMP test demonstrated significant clinical value as it yielded the only abnormal test results in some patients suffering from a unilateral vestibular schwannoma. For oVEMPs, we suggest that ACS stimulation should be the initial test. In patients who responded to ACS and who had normal responses, BCV was not required. In patients with abnormal responses on the affected side using ACS, BCV at AFz should be used to confirm abnormal function of the superior vestibular nerve. In patients who exhibited no responses on either side to ACS, BCV was the only approach allowing assessment of the function of the superior vestibular nerve. We favor using AFz stimulation first because it is easier to perform in clinical practice than mastoid stimulation. PMID:25137289

Chiarovano, Elodie; Darlington, Cynthia; Vidal, Pierre-Paul; Lamas, Georges; de Waele, Catherine

2014-01-01

342

Complex vestibular macular anatomical relationships need a synthetic approach  

NASA Technical Reports Server (NTRS)

Mammalian vestibular maculae are anatomically organized for complex parallel processing of linear acceleration information. Anatomical findings in rat maculae are provided in order to underscore this complexity, which is little understood functionally. This report emphasizes that a synthetic approach is critical to understanding how maculae function and the kind of information they conduct to the brain.

Ross, M. D.

2001-01-01

343

Potential solutions to several vestibular challenges facing clinicians  

PubMed Central

Among other problems, patients with vestibular problems suffer imbalance, spatial disorientation, and blurred vision. These problems lead to varying degrees of disability and can be debilitating. Unfortunately, a large number of patients with vestibular complaints cannot be diagnosed with the clinical tests available today. Nor do we have treatments for all patients that we can diagnose. These clinical problems provide challenges to and opportunities for the field of vestibular research. In this paper, we discuss some new diagnostic and treatment options that could become available for tomorrow’s patients. As a new diagnostic, we have begun measuring patient’s perceptual direction-detection thresholds. Preliminary results appear encouraging; patients diagnosed with bilateral loss have yaw rotation thresholds almost ten times greater than normals, while patients diagnosed with migraine associated vertigo have roll tilt thresholds well below normal at 0.1 Hz. As a new treatment, we have performed animal studies looking at responses evoked by electrical stimulation provided by a vestibular prosthesis. Results measuring the VOR demonstrate promise and preliminary studies of balance and perception are also encouraging. While electrical stimulation is a standard means of stimulation, optical stimulation is also being investigated as a way to improve prosthetic stimulation specificity. PMID:20555169

Merfeld, Daniel M.; Priesol, Adrian; Lee, Daniel; Lewis, Richard F.

2010-01-01

344

Vestibular rehabilitation outcomes: velocity trajectory analysis of repeated bench stepping  

Microsoft Academic Search

Objectives: To quantify vestibular rehabilitation (VR) outcomes in patients with vestibulospinal reflex pathology (VSP) using a new technique, high curvature analysis (HCA), that measures space trajectory stability.Methods: Twelve patients with VSP and 10 healthy controls performed a repeated stepping task in a motion analysis laboratory. Patients with VSP were tested before and after a 12 week VR program. Three dimensional

Dov Goldvasser; Chris A McGibbon; David E Krebs

2000-01-01

345

The Development of Vestibular Connections in Rat Embryos in Microgravity  

NASA Technical Reports Server (NTRS)

Existing experimental embryological data suggests that the vestibular system initially develops in a very rigid and genetically controlled manner. Nevertheless, gravity appears to be a critical factor in the normal development of the vestibular system that monitors position with respect to gravity (saccule and utricle). In fact several studies have shown that prenatal exposure to microgravity causes temporary deficits in gravity-dependent righting behaviors, and prolonged exposure to hypergravity from conception to weaning causes permanent deficits in gravity-dependent righting behaviors. Data on hypergravity and microgravity exposure suggest some changes in the otolith formation during development, in particular the size although these changes may actually vary with the species involved. In adults exposed to microgravity there is a change in the synaptic density in the otic sensory epithelia suggesting that some adaptation may occur there. However, effects have also been reported in the brainstem. Several studies have shown synaptic changes in the lateral vestibular nucleus and in the nodulus of the cerebellum after neonatal exposure to hypergravity. We report here that synaptogenesis in the medial vestibular nucleus is retarded in developing rat embryos that were exposed to microgravity from gestation days 9 to 19.

Bruce, Laura L.; Fritzsch, Bernd

1997-01-01

346

Tests of walking balance for screening vestibular disorders  

PubMed Central

Few reliable tests are available for screening people rapidly for vestibular disorders although such tests would be useful for a variety of testing situations. Balance testing is widely performed but of unknown value for screening. The goal of this study was to determine the value of tests of walking balance for screening people with vestibular impairments. We tested three groups of patients with known vestibular impairments: benign paroxysmal positional vertigo, unilateral vestibular weakness, and post-acoustic neuroma resection. We compared them to normal subjects. All subjects were independently ambulatory without gait aids. Subjects were tested on tandem walking (TW) with eyes open and eyes closed for 10 steps, walking with no additional head motions and with augmented head rotations in yaw for 7 m (WwHT), and an obstacle avoidance task, the Functional Mobility Test (FMT). Subjects wore a 3-D motion sensor centered at mid-torso to capture kinematic measures. Patients and normals differed significantly on some behavioral measures, such as the number of steps to perform TW, and on some but not all kinematic measures. ROC analyses, however, were at best only moderate, and failed to find strong differences and cut-points that would differentiate the groups. These findings suggest that although patients and normals differ in performance of these tests in some interesting ways the groups are not sufficiently different on these tests for easy use as screening tests to differentiate the populations. PMID:23000609

Cohen, Helen S.; Mulavara, Ajitkumar P.; Peters, Brian T.; Sangi-Haghpeykar, Haleh; Bloomberg, Jacob J.

2013-01-01

347

Linear Path Integration Deficits in Patients with Abnormal Vestibular Afference  

PubMed Central

Effective navigation requires the ability to keep track of one’s location and maintain orientation during linear and angular displacements. Path integration is the process of updating the representation of body position by integrating internally-generated self-motion signals over time (e.g., walking in the dark). One major source of input to path integration is vestibular afference. We tested patients with reduced vestibular function (unilateral vestibular hypofunction, UVH), patients with aberrant vestibular function (benign paroxysmal positional vertigo, BPPV), and healthy participants (controls) on two linear path integration tasks: experimenter-guided walking and target-directed walking. The experimenter-guided walking task revealed a systematic underestimation of self-motion signals in UVH patients compared to the other groups. However, we did not find any difference in the distance walked between the UVH group and the control group for the target-directed walking task. Results from neuropsychological testing and clinical balance measures suggest that the errors in experimenter-guided walking were not attributable to cognitive and/or balance impairments. We conclude that impairment in linear path integration in UVH patients stem from deficits in self-motion perception. Importantly, our results also suggest that patients with a UVH deficit do not lose their ability to walk accurately without vision to a memorized target location. PMID:22726251

Arthur, Joeanna C.; Kortte, Kathleen B.; Shelhamer, Mark; Schubert, Michael C.

2014-01-01

348

Mechanisms for vestibular disorders in space flight. Facts and hypotheses  

NASA Technical Reports Server (NTRS)

This article discusses the vestibular disorders associated with space flight. It is found there is still no complete understanding of the changes occurring in the sensory systems of the body during weightlessness. Results of studies are presented, including results of a ground model.

Matsnev, E. I.

1980-01-01

349

Physiological responses of frog vestibular fibers to horizontal angular rotation  

Microsoft Academic Search

1.Single neuronal discharges in frog's vestibular nerve were recorded in unanesthetized preparations with glass microelectrodes. The nerve fibers supplying the horizontal semicircular canal are divided into two types according to the characteristics of their frequency responses to natural stimulation of the horizontal canal. The afferent fibers increase their firing rate only on ipsilateral rotation and cease to fire on contralateral

W. Precht; R. Llinás; M. Clarke

1971-01-01

350

Mission Specialist (MS) Allen conducts Vestibular Study Experiment on middeck  

NASA Technical Reports Server (NTRS)

Mission Specialist (MS) Allen, wearing headset and with electrodes placed on his face, relaxes on middeck floor while Vestibular Study Experiment hardware records eye movement data as it relates to motion sickness. The electrodes monitor his responses in zero gravity. Allen is wearing the multi-pieced constant wear garment.

1982-01-01

351

Vestibular autorotation testing in patients with benign paroxysmal positional vertigo  

Microsoft Academic Search

Objectives: The current gold standard for diagnosis of benign paroxysmal positional vertigo (BPPV) is the Dix-Hallpike maneuver. However, because of fatigability, the Dix-Hallpike is often falsely normal. The objective of this study was to evaluate the utility of vestibular autorotation testing in the diagnosis of BPPV. Methods: The charts of 210 patients at a tertiary referral center for vertiginous disorders

PETER BELAFSKY; GERARD GIANOLI; JAMES SOILEAU; DAVID MOORE; SHERI DAVIDOWITZ

2000-01-01

352

Vestibular testing in patients with panic disorder and chronic dizziness  

PubMed Central

Summary In order to investigate the relationship between chronic dizziness and vestibular function in patients with panic disorder, in the present study neurotologic findings in 15 patients with panic disorder and chronic dizziness were compared with those in 15 patients with chronic dizziness, without panic disorder. All underwent neurotologic screening for spontaneous, positional and positioning nystagmus with head-shaking and head-thrust tests, an audiometric examination and electronystagmography with bithermal stimulation according to Freyss. A significantly higher number of patients with panic disorder and chronic dizziness showed pathological neurotologic findings in comparison to subjects with chronic dizziness only (9 and 2 patients, respectively; p < 0.05). Most patients with panic disorder showed signs of peripheral vestibular disorders. These results suggest that the complaint of dizziness in patients with panic disorder may be linked to a malfunction of the vestibular system and vestibular disorders may play a role in the pathophysiology of panic disorder. Possible mechanisms underlying this finding are discussed. In patients with panic disorder and chronic dizziness between panic attacks, a careful neurotologic examination is warranted. PMID:18198754

Teggi, R; Caldirola, D; Bondi, S; Perna, G; Bellodi, L; Bussi, M

2007-01-01

353

Nystagmus during Attacks of Vestibular Migraine: An Aid in Diagnosis  

Microsoft Academic Search

Introduction: An estimated one-fourth to one-third of patients with migraine will experience vertigo associated with their migraine attacks. Vestibular migraine frequently presents as a diagnostic challenge as objective neurological findings consistent with this entity have not been well described. Objective: The aim of this study is to characterize eye movements of patients presenting with nystagmus during attacks of migrainous vertigo.

Sharon Hartman Polensek; Ronald J. Tusa

2010-01-01

354

Monothermal caloric test its value in assessment of vestibular function  

Microsoft Academic Search

Background: The usefulness of either cool or warm caloric stimulation alone has been suggested as a screening tool for unilateral vestibular weakness. Previously researchers have reported false-negative rates ranging from 0% to 52% for either cool or warm stimulation depending on variable failure criteria. Objective: To re-evaluate the monothermal caloric test before it can be routinely used in clinical settings.

A. Sameh Farid; Shereen M. El-Abd; Maha H. Abou-Elew

2003-01-01

355

Spatial orientation of the vestibular system  

NASA Technical Reports Server (NTRS)

1. A simplified three-dimensional state space model of visual vestibular interaction was formulated. Matrix and dynamical system operators representing coupling from the semicircular canals and the visual system to the velocity storage integrator were incorporated into the model. 2. It was postulated that the system matrix for a tilted position was a composition of two linear transformations of the system matrix for the upright position. One transformation modifies the eigenvalues of the system matrix while another rotates the pitch and roll eigenvectors with the head, while maintaining the yaw axis eigenvector approximately spatially invariant. Using this representation, the response characteristics of the pitch, roll, and yaw eye velocity were obtained in terms of the eigenvalues and associated eigenvectors. 3. Using OKAN data obtained from monkeys and comparing to the model predictions, the eigenvalues and eigenvectors of the system matrix were identified as a function of tilt to the side or of tilt to the prone positions, using a modification of the Marquardt algorithm. The yaw eigenvector for right-side-down tilt and for downward pitch cross-coupling was approximately 30 degrees from the spatial vertical. For the prone position, the eigenvector was computed to be approximately 20 degrees relative to the spatial vertical. For both side-down and prone positions, oblique OKN induced along eigenvector directions generated OKAN which decayed to zero along a straight line with approximately a single time constant. This was verified by a spectral analysis of the residual sequence about the straight line fit to the decaying data. The residual sequence was associated with a narrow autocorrelation function and a wide power spectrum. 4. Parameters found using the Marquardt algorithm were incorporated into the model. Diagonal matrices in a head coordinate frame were introduced to represent the direct pathway and the coupling of the visual system to the integrator. Model simulations predicted the behavior of yaw and pitch OKN and OKAN when the animal was upright, as well as the cross-coupling in the tilted position. The trajectories in velocity space were also accurately simulated. 5. There were similarities between the monkey eigenvectors and human perception of the spatial vertical. For side-down tilts and downward eye velocity cross-coupling, there was only an Aubert (A) effect. For upward eye velocity cross-coupling there were both Muller (E) and Aubert (A) effects. The mean of the eigenvectors for upward and downward eye velocities overlay human 1 x g perceptual data.(ABSTRACT TRUNCATED AT 400 WORDS).

Raphan, T.; Dai, M.; Cohen, B.

1992-01-01

356

QB1 - Stochastic Gene Regulation  

SciTech Connect

Summaries of this presentation are: (1) Stochastic fluctuations or 'noise' is present in the cell - Random motion and competition between reactants, Low copy, quantization of reactants, Upstream processes; (2) Fluctuations may be very important - Cell-to-cell variability, Cell fate decisions (switches), Signal amplification or damping, stochastic resonances; and (3) Some tools are available to mode these - Kinetic Monte Carlo simulations (SSA and variants), Moment approximation methods, Finite State Projection. We will see how modeling these reactions can tell us more about the underlying processes of gene regulation.

Munsky, Brian [Los Alamos National Laboratory

2012-07-23

357

Artificial Balance: Restoration of the Vestibulo-Ocular Reflex in Humans with a Prototype Vestibular Neuroprosthesis  

PubMed Central

The vestibular system plays a crucial role in the multisensory control of balance. When vestibular function is lost, essential tasks such as postural control, gaze stabilization, and spatial orientation are limited and the quality of life of patients is significantly impaired. Currently, there is no effective treatment for bilateral vestibular deficits. Research efforts both in animals and humans during the last decade set a solid background to the concept of using electrical stimulation to restore vestibular function. Still, the potential clinical benefit of a vestibular neuroprosthesis has to be demonstrated to pave the way for a translation into clinical trials. An important parameter for the assessment of vestibular function is the vestibulo-ocular reflex (VOR), the primary mechanism responsible for maintaining the perception of a stable visual environment while moving. Here we show that the VOR can be artificially restored in humans using motion-controlled, amplitude modulated electrical stimulation of the ampullary branches of the vestibular nerve. Three patients received a vestibular neuroprosthesis prototype, consisting of a modified cochlear implant providing vestibular electrodes. Significantly higher VOR responses were observed when the prototype was turned ON. Furthermore, VOR responses increased significantly as the intensity of the stimulation increased, reaching on average 79% of those measured in healthy volunteers in the same experimental conditions. These results constitute a fundamental milestone and allow us to envision for the first time clinically useful rehabilitation of patients with bilateral vestibular loss. PMID:24808890

Perez Fornos, Angelica; Guinand, Nils; van de Berg, Raymond; Stokroos, Robert; Micera, Silvestro; Kingma, Herman; Pelizzone, Marco; Guyot, Jean-Philippe

2014-01-01

358

Stochastic thermodynamics  

NASA Astrophysics Data System (ADS)

'Stochastic thermodynamics as a conceptual framework combines the stochastic energetics approach introduced a decade ago by Sekimoto [1] with the idea that entropy can consistently be assigned to a single fluctuating trajectory [2]'. This quote, taken from Udo Seifert's [3] 2008 review, nicely summarizes the basic ideas behind stochastic thermodynamics: for small systems, driven by external forces and in contact with a heat bath at a well-defined temperature, stochastic energetics [4] defines the exchanged work and heat along a single fluctuating trajectory and connects them to changes in the internal (system) energy by an energy balance analogous to the first law of thermodynamics. Additionally, providing a consistent definition of trajectory-wise entropy production gives rise to second-law-like relations and forms the basis for a 'stochastic thermodynamics' along individual fluctuating trajectories. In order to construct meaningful concepts of work, heat and entropy production for single trajectories, their definitions are based on the stochastic equations of motion modeling the physical system of interest. Because of this, they are valid even for systems that are prevented from equilibrating with the thermal environment by external driving forces (or other sources of non-equilibrium). In that way, the central notions of equilibrium thermodynamics, such as heat, work and entropy, are consistently extended to the non-equilibrium realm. In the (non-equilibrium) ensemble, the trajectory-wise quantities acquire distributions. General statements derived within stochastic thermodynamics typically refer to properties of these distributions, and are valid in the non-equilibrium regime even beyond the linear response. The extension of statistical mechanics and of exact thermodynamic statements to the non-equilibrium realm has been discussed from the early days of statistical mechanics more than 100 years ago. This debate culminated in the development of linear response theory for small deviations from equilibrium, in which a general framework is constructed from the analysis of non-equilibrium states close to equilibrium. In a next step, Prigogine and others developed linear irreversible thermodynamics, which establishes relations between transport coefficients and entropy production on a phenomenological level in terms of thermodynamic forces and fluxes. However, beyond the realm of linear response no general theoretical results were available for quite a long time. This situation has changed drastically over the last 20 years with the development of stochastic thermodynamics, revealing that the range of validity of thermodynamic statements can indeed be extended deep into the non-equilibrium regime. Early developments in that direction trace back to the observations of symmetry relations between the probabilities for entropy production and entropy annihilation in non-equilibrium steady states [5-8] (nowadays categorized in the class of so-called detailed fluctuation theorems), and the derivations of the Bochkov-Kuzovlev [9, 10] and Jarzynski relations [11] (which are now classified as so-called integral fluctuation theorems). Apart from its fundamental theoretical interest, the developments in stochastic thermodynamics have experienced an additional boost from the recent experimental progress in fabricating, manipulating, controlling and observing systems on the micro- and nano-scale. These advances are not only of formidable use for probing and monitoring biological processes on the cellular, sub-cellular and molecular level, but even include the realization of a microscopic thermodynamic heat engine [12] or the experimental verification of Landauer's principle in a colloidal system [13]. The scientific program Stochastic Thermodynamics held between 4 and 15 March 2013, and hosted by The Nordic Institute for Theoretical Physics (Nordita), was attended by more than 50 scientists from the Nordic countries and elsewhere, amongst them many leading experts in the field. During the program, the most recent developments, open quest

Eichhorn, Ralf; Aurell, Erik

2014-04-01

359

Visual-vestibular integration motion perception reporting  

NASA Technical Reports Server (NTRS)

Self-orientation and self/surround-motion perception derive from a multimodal sensory process that integrates information from the eyes, vestibular apparatus, proprioceptive and somatosensory receptors. Results from short and long duration spaceflight investigations indicate that: (1) perceptual and sensorimotor function was disrupted during the initial exposure to microgravity and gradually improved over hours to days (individuals adapt), (2) the presence and/or absence of information from different sensory modalities differentially affected the perception of orientation, self-motion and surround-motion, (3) perceptual and sensorimotor function was initially disrupted upon return to Earth-normal gravity and gradually recovered to preflight levels (individuals readapt), and (4) the longer the exposure to microgravity, the more complete the adaptation, the more profound the postflight disturbances, and the longer the recovery period to preflight levels. While much has been learned about perceptual and sensorimotor reactions and adaptation to microgravity, there is much remaining to be learned about the mechanisms underlying the adaptive changes, and about how intersensory interactions affect perceptual and sensorimotor function during voluntary movements. During space flight, SMS and perceptual disturbances have led to reductions in performance efficiency and sense of well-being. During entry and immediately after landing, such disturbances could have a serious impact on the ability of the commander to land the Orbiter and on the ability of all crew members to egress from the Orbiter, particularly in a non-nominal condition or following extended stays in microgravity. An understanding of spatial orientation and motion perception is essential for developing countermeasures for Space Motion Sickness (SMS) and perceptual disturbances during spaceflight and upon return to Earth. Countermeasures for optimal performance in flight and a successful return to Earth require the development of preflight and in-flight training to help astronauts acquire and maintain a dual adaptive state. Despite the considerable experience with, and use of, an extensive set of countermeasures in the Russian space program, SMS and perceptual disturbances remain an unresolved problem on long-term flights. Reliable, valid perceptual reports are required to develop and refine stimulus rearrangements presented in the PAT devices currently being developed as countermeasures for the prevention of motion sickness and perceptual disturbances during spaceflight, and to ensure a less hazardous return to Earth. Prior to STS-8, crew member descriptions of their perceptual experiences were, at best, anecdotal. Crew members were not schooled in the physiology or psychology of sensory perception, nor were they exposed to the appropriate professional vocabulary. However, beginning with the STS-8 Shuttle flight, a serious effort was initiated to teach astronauts a systematic method to classify and quantify their perceptual responses in space, during entry, and after flight. Understanding, categorizing, and characterizing perceptual responses to spaceflight has been greatly enhanced by implementation of that training system.

Harm, Deborah L.; Reschke, Millard R.; Parker, Donald E.

1999-01-01

360

Effects of vestibular and balance rehabilitation on sensory organization and dizziness handicap.  

PubMed

This retrospective study was undertaken to assess balance recovery and dizziness handicap in 32 patients after a vestibular and balance rehabilitation program. Outcomes were compared between 12 patients with peripheral vestibular disorders and 20 patients with central or mixed balance disorders. The patients were tested with posturography (sensory organization test [SOT]) and the Dizziness Handicap Inventory (DHI) before and after their therapy program. The vestibular SOT, composite SOT, and functional DHI scores obtained before and after exercise were significantly improved in both the peripheral and central groups. The visual SOT mean scores obtained before and after therapy were significantly different only for the group with central or mixed vestibular disorders. Changes in SOT scores were not directly correlated with changes in DHI scores. Outcome measures of vestibular rehabilitation protocols confirmed objective and subjective improvement of balance and dizziness handicap in patients with peripheral and central vestibular disorders. PMID:15697162

Badke, Mary Beth; Miedaner, James A; Shea, Terry A; Grove, Colin R; Pyle, G Mark

2005-01-01

361

To develop behavioral tests of vestibular functioning in the Wistar rat  

NASA Technical Reports Server (NTRS)

Two tests of vestibular functioning in the rat were developed. The first test was the water maze. In the water maze the rat does not have the normal proprioceptive feedback from its limbs to help it maintain its orientation, and must rely primarily on the sensory input from its visual and vestibular systems. By altering lighting conditions and visual cues the vestibular functioning without visual cues was assessed. Whether there was visual compensation for some vestibular dysfunction was determined. The second test measured vestibular functioning of the rat's behavior on a parallel swing. In this test the rat's postural adjustments while swinging on the swing with the otoliths being stimulated were assessed. Less success was achieved in developing the parallel swing as a test of vestibular functioning than with the water maze. The major problem was incorrect initial assumptions of what the rat's probable behavior on the parallel swing would be.

Nielson, H. C.

1980-01-01

362

Complementary roles of BDNF and NT3 in vestibular and auditory development  

Microsoft Academic Search

The physiological role of BDNF and NT-3 in the development of the vestibular and auditory systems was investigated in mice that carry a deleted BDNF and\\/or NT-3 gene. BDNF was the major survival factor for vestibular ganglion neurons, and NT-3, for spiral ganglion neurons. Lack of BDNF and NT-3 did not affect ingrowth of nerve fibers into the vestibular epithelium,

Patrik Ernfors; Thomas Van De Water; Janet Loring; Rudolf Jaenisch

1995-01-01

363

The vestibular system: a spatial reference for bodily self-consciousness  

PubMed Central

Self-consciousness is the remarkable human experience of being a subject: the “I”. Self-consciousness is typically bound to a body, and particularly to the spatial dimensions of the body, as well as to its location and displacement in the gravitational field. Because the vestibular system encodes head position and movement in three-dimensional space, vestibular cortical processing likely contributes to spatial aspects of bodily self-consciousness. We review here recent data showing vestibular effects on first-person perspective (the feeling from where “I” experience the world) and self-location (the feeling where “I” am located in space). We compare these findings to data showing vestibular effects on mental spatial transformation, self-motion perception, and body representation showing vestibular contributions to various spatial representations of the body with respect to the external world. Finally, we discuss the role for four posterior brain regions that process vestibular and other multisensory signals to encode spatial aspects of bodily self-consciousness: temporoparietal junction, parietoinsular vestibular cortex, ventral intraparietal region, and medial superior temporal region. We propose that vestibular processing in these cortical regions is critical in linking multisensory signals from the body (personal and peripersonal space) with external (extrapersonal) space. Therefore, the vestibular system plays a critical role for neural representations of spatial aspects of bodily self-consciousness. PMID:24860446

Pfeiffer, Christian; Serino, Andrea; Blanke, Olaf

2014-01-01

364

Vestibular function in the temporal and parietal cortex: distinct velocity and inertial processing pathways.  

PubMed

A number of behavioral and neuroimaging studies have reported converging data in favor of a cortical network for vestibular function, distributed between the temporo-parietal cortex and the prefrontal cortex in the primate. In this review, we focus on the role of the cerebral cortex in visuo-vestibular integration including the motion sensitive temporo-occipital areas i.e., the middle superior temporal area (MST) and the parietal cortex. Indeed, these two neighboring cortical regions, though they both receive combined vestibular and visual information, have distinct implications in vestibular function. In sum, this review of the literature leads to the idea of two separate cortical vestibular sub-systems forming (1) a velocity pathway including MST and direct descending pathways on vestibular nuclei. As it receives well-defined visual and vestibular velocity signals, this pathway is likely involved in heading perception and rapid top-down regulation of eye/head coordination and (2) an inertial processing pathway involving the parietal cortex in connection with the subcortical vestibular nuclei complex responsible for velocity storage integration. This vestibular cortical pathway would be implicated in high-order multimodal integration and cognitive functions, including world space and self-referential processing. PMID:25071481

Ventre-Dominey, Jocelyne

2014-01-01

365

Experimental and clinical study of EHF treatment of vascular-vestibular dysfunction  

SciTech Connect

The authors present the results of a study of the effectiveness of EHF radiation on the cerebral hemodynamics, bioelectrical activity of the cerebral cortex, and functional state of the vestibular analyzer in chronic studies of cats using a model of vascular-vestibular dysfunction. The clinical part of the work reflects the results of studies of the functional state of cerebral blood circulation and the vestibular analyzer during the EHF treatment of angiovertebrogenic vestibular dysfunction in a background of initial manifestations of cerebral blood supply deficiency (angiodistonic variant).

Mal`tsev, A.E.; Abakarov, A.T.; Istomin, V.S. [and others

1994-07-01

366

Vestibular function in the temporal and parietal cortex: distinct velocity and inertial processing pathways  

PubMed Central

A number of behavioral and neuroimaging studies have reported converging data in favor of a cortical network for vestibular function, distributed between the temporo-parietal cortex and the prefrontal cortex in the primate. In this review, we focus on the role of the cerebral cortex in visuo-vestibular integration including the motion sensitive temporo-occipital areas i.e., the middle superior temporal area (MST) and the parietal cortex. Indeed, these two neighboring cortical regions, though they both receive combined vestibular and visual information, have distinct implications in vestibular function. In sum, this review of the literature leads to the idea of two separate cortical vestibular sub-systems forming (1) a velocity pathway including MST and direct descending pathways on vestibular nuclei. As it receives well-defined visual and vestibular velocity signals, this pathway is likely involved in heading perception and rapid top-down regulation of eye/head coordination and (2) an inertial processing pathway involving the parietal cortex in connection with the subcortical vestibular nuclei complex responsible for velocity storage integration. This vestibular cortical pathway would be implicated in high-order multimodal integration and cognitive functions, including world space and self-referential processing. PMID:25071481

Ventre-Dominey, Jocelyne

2014-01-01

367

Response suppression produced by vestibular stimulation in the rat.  

PubMed

Seven rats were trained to stable performance levels on either Fixed Ratio 47, Variable Ratio 47, Variable Interval 1-min, or Fixed Interval 1-min schedules of food reinforcement. Subjects were then tested for sensitivity to vestibular stimulation from rotation, using an ascending method of limits technique with increments in velocity of one revolution per minute every 5 min. Centrifugal forces were minimized by locating the test chamber over the axis of rotation. Response rates decreased in all subjects as a function of increasing rotation speed. In addition, characteristic differences in the patterns of response decrement were found between subjects on ratio and on interval schedules. Repeated tests indicated high intra-subject reliability in sensitivity to rotation. Similarities of these data to "motion sickness" phenomena in other species were noted. It is suggested that this behavioral approach provides a sensitive and quantifiable technique for assessing the effects of vestibular stimulation in animals. PMID:5302438

Riccio, D C; Thach, J S

1968-07-01

368

A model describing vestibular detection of body sway motion.  

NASA Technical Reports Server (NTRS)

An experimental technique was developed which facilitated the formulation of a quantitative model describing vestibular detection of body sway motion in a postural response mode. All cues, except vestibular ones, which gave a subject an indication that he was beginning to sway, were eliminated using a specially designed two-degree-of-freedom platform; body sway was then induced and resulting compensatory responses at the ankle joints measured. Hybrid simulation compared the experimental results with models of the semicircular canals and utricular otolith receptors. Dynamic characteristics of the resulting canal model compared closely with characteristics of models which describe eye movement and subjective responses to body rotational motions. The average threshold level, in the postural response mode, however, was considerably lower. Analysis indicated that the otoliths probably play no role in the initial detection of body sway motion.

Nashner, L. M.

1971-01-01

369

Effects of Weightlessness on Vestibular Development of Quail  

NASA Technical Reports Server (NTRS)

The lack of gravity is known to alter vestibular responses in developing and adult vertebrates. One cause of these altered responses may be changes in the connections between the vestibular receptor and the brain. Therefore we propose to investigate the effects of gravity on the formations of connections between the gravity receptors of the ear and the brain in developing quail incubated in space beginning at an age before these connections are established (incubation day three) until near the time of hatching, when they are to some extent functional. This investigation will make use of a novel technique, the diffusion of a lipophilic dye, DiI, in fixed tissue. This technique can thus be used to analyze the connections in specimens fixed in orbit, thus eliminating changes due to the earth's gravity. The evaluation of the data will enable us to detect gross deviations from normal patterns as well as detailed quantitative deviations.

Fritzsch, Bernd; Bruce, Laura L.

1997-01-01

370

Bilateral vestibular hypofunction in neurosarcoidosis: a case report.  

PubMed

We describe the case of a 59-year-old woman who presented with progressive bilateral vestibular hypofunction and who was found to have bilateral granulomatous mass lesions of the mesial temporal lobe. Initially, her condition stabilized neurologically with corticosteroids, but a diagnosis of neurosarcoidosis was delayed because of the unusual presentation and persistently normal chest imaging results and serum angiotensin-converting enzyme (ACE) levels. Approximately 1 year after her initial presentation, the patient died of complications of a myocardial infarction and pulmonary embolism. Sarcoidosis should be considered in the differential diagnosis of idiopathic bilateral vestibular hypofunction even if the chest imaging and serum ACE levels are normal, particularly when there is evidence of a multisystem process. PMID:21229491

Smith, Jonathan H; Stovall, Kyndra C; Coons, Stephen; Fife, Terry Douglas

2011-01-01

371

Research on biophysical evaluation of the human vestibular system  

NASA Technical Reports Server (NTRS)

The human vestibular function was studied by the combined approach of advanced measurement and mathematical modelling. Fundamental measurements of some physical properties of endolymph and perilymph, combined with nystagmus measurements and fluid mechanical analysis of semicircular canal function furthered the theory of canal mechanical response to angular acceleration, caloric stimulation and relating linear acceleration. The effects of adaptation seen at low frequency angular stimulation were studied and modelled to remove some shortcomings of the torsion pendulum models. Otolith function was also studied experimentally and analytically, leading to a new set of models for subjective orientation. Applications to special problems of space, including the case of rotating spacecraft were investigated and the interaction of visual and vestibular cues and their relation to proprioceptive information was explored relative to postural control.

Young, L. R.

1974-01-01

372

Alignment of angular velocity sensors for a vestibular prosthesis.  

PubMed

Vestibular prosthetics transmit angular velocities to the nervous system via electrical stimulation. Head-fixed gyroscopes measure angular motion, but the gyroscope coordinate system will not be coincident with the sensory organs the prosthetic replaces. Here we show a simple calibration method to align gyroscope measurements with the anatomical coordinate system. We benchmarked the method with simulated movements and obtain proof-of-concept with one healthy subject. The method was robust to misalignment, required little data, and minimal processing. PMID:22329908

Digiovanna, Jack; Carpaneto, Jacopo; Micera, Silvestro; Merfeld, Daniel M

2012-01-01

373

Galvanic vestibular stimulation in hemi-spatial neglect  

PubMed Central

Hemi-spatial neglect is an attentional disorder in which the sufferer fails to acknowledge or respond to stimuli appearing in contralesional space. In recent years, it has become clear that a measurable reduction in contralesional neglect can occur during galvanic vestibular stimulation, a technique by which transmastoid, small amplitude current induces lateral, attentional shifts via asymmetric modulation of the left and right vestibular nerves. However, it remains unclear whether this reduction persists after stimulation is stopped. To estimate longevity of effect, we therefore conducted a double-blind, randomized, dose-response trial involving a group of stroke patients suffering from left-sided neglect (n = 52, mean age = 66 years). To determine whether repeated sessions of galvanic vestibular stimulation more effectively induce lasting relief than a single session, participants received 1, 5, or 10 sessions, each lasting 25 min, of sub-sensory, left-anodal right-cathodal noisy direct current (mean amplitude = 1 mA). Ninety five percent confidence intervals indicated that all three treatment arms showed a statistically significant improvement between the pre-stimulation baseline and the final day of stimulation on the primary outcome measure, the conventional tests of the Behavioral Inattention Test. More remarkably, this change (mean change = 28%, SD = 18) was still evident 1 month later. Secondary analyses indicated an allied increase of 20% in median Barthel Index (BI) score, a measure of functional capacity, in the absence of any adverse events or instances of participant non-compliance. Together these data suggest that galvanic vestibular stimulation, a simple, cheap technique suitable for home-based administration, may produce lasting reductions in neglect that are clinically important. Further protocol optimization is now needed ahead of a larger effectiveness study. PMID:24523679

Wilkinson, David; Zubko, Olga; Sakel, Mohamed; Coulton, Simon; Higgins, Tracy; Pullicino, Patrick

2014-01-01

374

Comparative anatomy of the vestibular nuclear complex in submammalian vertebrates.  

NASA Technical Reports Server (NTRS)

A synopsis of the literature on the natural history of the vestibular nuclear complex (VNC) in lower vertebrates is presented in an attempt to assess the knowledge available. The review discloses that there is considerable descriptive information that is widely dispersed in the literature. However, information about the topology, number, and cellular composition of the cell groups that compose the VNC is sketchy. Major cytological and hodological information is still needed to establish which parts of the VNC actually are homologous.

Mehler, W. R.

1972-01-01

375

Vestibular and taste disorders after bilateral cochlear implantation  

Microsoft Academic Search

The objective of this study was to investigate the occurrence of vestibular receptor deficiency and taste disorders after\\u000a bilateral cochlear implantation in postlingually deafened patients and to find out whether the risk for these complications\\u000a is higher for the second implantation. In a retrospective cohort study, we examined 20 patients (11–58 years, mean age 41.5 years),\\u000a implanted sequentially between 2000 and 2007

Jan H. WagnerDietmar; Dietmar Basta; Friederike Wagner; Rainer O. Seidl; Arneborg Ernst; Ingo Todt

2010-01-01

376

The effects of cochlear implantation on vestibular function  

PubMed Central

Objective Determine the risk posed by cochlear implantation (CI) to the labyrinth. Study Design Prospective cohort study. Setting Academic tertiary referral center. Patients Thirty-six ears belonging to 35 adult CI candidates (mean: 46, range: 23–69 years old). Intervention Cochlear implantation. Main Outcome Measures Vestibular function was assessed using the quantitative 3D head impulse test (qHIT), clinical head impulse test (cHIT), post-headshake nystagmus (HSN), caloric electronystagmography (ENG), vestibular-evoked myogenic potentials (VEMP), dynamic visual acuity (DVA), and Dizziness Handicap Inventory (DHI). Results All 36 ears were tested using qHIT before CI, and 28 ears were tested 4–8 weeks after CI. Quantitative HIT showed 1/28 of ears suffered reduced function. Clinical HIT was 44% sensitive and 94% specific for identification of severe-to-profound vestibular hypofunction confirmed by qHIT. HSN was unchanged in 11/11 subjects. New hyporeflexia was found in 1/16 of ENG-tested ears. VEMP showed either a disappearance of response or an increase in threshold by >10dB in 5/16 ears. Passive DVA showed no change in 16/16 ears. DHI scores worsened in 3/28 and improved in 4/28 subjects. Conclusions Although small, the observed rate of labyrinthine injury was comparable to that for other risks of CI. Thus, it is important to educate CI candidates about possible risk to balance function, particularly when CI of an “only balancing ear” is contemplated. Clinical HIT is useful for detecting severe high-frequency vestibular hypofunction and should be part of the pre-CI physical examination. PMID:19108038

Melvin, Thuy-Anh N.; Della Santina, Charles C.; Carey, John P.; Migliaccio, Americo A.

2009-01-01

377

Counteracting Muscle Atrophy using Galvanic Stimulation of the Vestibular System  

NASA Technical Reports Server (NTRS)

The unloading of weight bearing from antigravity muscles during space flight produces significant muscle atrophy and is one of the most serious health problems facing the space program. Various exercise regimens have been developed and used either alone or in combination with pharmacological techniques to ameliorate this atrophy, but no effective countermeasure exists for this problem. The research in this project was conducted to evaluate the potential use of vestibular galvanic stimulation (VGS) to prevent muscle atrophy resulting from unloading of weight bearing from antigravity muscles. This approach was developed based on two concepts related to the process of maintaining the status of the anti-gravity neuromuscular system. These two premises are: (1) The "tone," or bias on spinal motorneurons is affected by vestibular projections that contribute importantly to maintaining muscle health and status. (2) VGS can be used to modify the excitability, or 'tone' of motorneuron of antigravity muscles. Thus, the strategy is to use VGS to modify the gain of vestibular projections to antigravity muscles and thereby change the general status of these muscles.

Fox, Robert A.; Polyakov, Igor

1999-01-01

378

Sleep and vestibular adaptation: implications for function in microgravity  

NASA Technical Reports Server (NTRS)

Optimal human performance depends upon integrated sensorimotor and cognitive functions, both of which are known to be exquisitely sensitive to loss of sleep. Under the microgravity conditions of space flight, adaptation of both sensorimotor (especially vestibular) and cognitive functions (especially orientation) must occur quickly--and be maintained--despite any concurrent disruptions of sleep that may be caused by microgravity itself, or by the uncomfortable sleeping conditions of the spacecraft. It is the three-way interaction between sleep quality, general work efficiency, and sensorimotor integration that is the subject of this paper and the focus of new work in our laboratory. To record sleep under field conditions including microgravity, we utilize a novel system called the Nightcap that we have developed and extensively tested on normal and sleep-disordered subjects. To perturb the vestibular system in ground-based studies, we utilize a variety of experimental conditions including optokinetic stimulation and both minifying and reversing goggle paradigms that have been extensively studied in relation to plasticity of the vestibulo-ocular reflex. Using these techniques we will test the hypothesis that vestibular adaptation both provokes and is enhanced by REM sleep under both ground-based and space conditions. In this paper we describe preliminary results of some of our studies.

Hobson, J. A.; Stickgold, R.; Pace-Schott, E. F.; Leslie, K. R.

1998-01-01

379

Regional differences in lectin binding patterns of vestibular hair cells  

NASA Technical Reports Server (NTRS)

Surface glycoconjugates of hair cells and supporting cells in the vestibular endorgans of the bullfrog were identified using biotinylated lectins with different carbohydrate specificities. Lectin binding in hair cells was consistent with the presence of glucose and mannose (CON A), galactose (RCA-I), N-acetylglucosamine (WGA), N-acetylgalactosamine (VVA), but not fucose (UEA-I) residues. Hair cells in the bullfrog sacculus, unlike those in the utriculus and semicircular canals, did not strain for N-acetylglucosamine (WGA) or N-acetylgalactosamine (VVA). By contrast, WGA and, to a lesser extent, VVA, differentially stained utricular and semicircular canal hair cells, labeling hair cells located in peripheral, but not central, regions. In mammals, WGA uniformly labeled Type I hair cells while labeling, as in the bullfrog, Type II hair cells only in peripheral regions. These regional variations were retained after enzymatic digestion. We conclude that vestibular hair cells differ in their surface glycoconjugates and that differences in lectin binding patterns can be used to identify hair cell types and to infer the epithelial origin of isolated vestibular hair cells.

Baird, R. A.; Schuff, N. R.; Bancroft, J.

1993-01-01

380

Regional differences in lectin binding patterns of vestibular hair cells  

NASA Technical Reports Server (NTRS)

Surface glycoconjugates of hair cells and supporting cells in the vestibular endorgans of the bullfrog were identified using biotinylated lectins with different carbohydrate specificities. Lectin binding in hair cells was consistent with the presence of glucose and mannose (CON A), galactose (RCA-I), N-acetylgalactosamine (VVA), but not fucose (UEA-I) residues. Hair cells in the bullfrog sacculus, unlike those in the utriculus and semicircular canals, did not stain for N-acetylglucosamine (WGA) or N-acetylgalactosamine (VVA). By contrast, WGA and, to a lesser extent, VVA, differentially stained utricular and semicircular canal hair cells, labeling hair cells located in peripheral, but not central, regions. In mammals, WGA uniformly labeled Type 1 hair cells while labeling, as in the bullfrog, Type 2 hair cells only in peripheral regions. These regional variations were retained after enzymatic digestion. We conclude that vestibular hair cells differ in their surface glycoconjugates and that differences in lectin binding patterns can be used to identify hair cell types and to infer the epithelial origin of isolated vestibular hair cells.

Baird, Richard A.; Schuff, N. R.; Bancroft, J.

1994-01-01

381

Human visual and vestibular heading perception in the vertical planes.  

PubMed

Heading estimation has not previously been reported in the vertical planes. This is a potentially interesting issue because although distribution of neuronal direction sensitivities is near uniform for vertical headings, there is an overrepresentation of otolith organs sensitive to motion in the horizontal relative to the vertical plane. Furthermore, thresholds of horizontal motion perception are considerably lower than those of vertical motion which has the potential to bias heading perception. The current data from 14 human subjects (age 19 to 67) measured heading estimation in response to vestibular motion of 14 cm (28 cm/s) over a 360° of headings at 5° intervals. An analogous visual motion was tested in separate trials. In this study, earth and head vertical/horizontal were always aligned. Results demonstrated that the horizontal component of heading was overestimated relative to the vertical component for vestibular heading stimuli in the coronal (skew) and sagittal (elevation) planes. For visual headings, the bias was much smaller and in the opposite direction such that the vertical component of heading was overestimated. Subjects older than 50 had significantly worse precision and larger biases relative to that of younger subjects for the vestibular conditions, although visual heading estimates were similar. A vector addition model was fit to the data which explains the observed heading biases by the known distribution of otolith organs in humans. The greatly decreased precision with age is explained by the model with decreases in end organ numbers, and relatively greater loss of otoliths that are sensitive to vertical motion. PMID:24249574

Crane, Benjamin T

2014-02-01

382

Caloric testing. 3. Patients with peripheral and central vestibular lesions.  

PubMed

Results of bithermal caloric testing in 83 patients with unilateral peripheral vestibular disease, cerebellopontine angle tumors and vertebrobasilar insufficiency were compared in order to find which response measurements identified the most abnormal responses in each disease category. A laboratory digital computer was used to quantitatively assess each caloric response and a large digital computer was used to statistically compare 110 measurements generated from each caloric test. Of the commonly used response parameters maximum slow component velocity (SVMx) and sum of slow amplitudes (SSA) were most sensitive in each category and duration of response (TDUR) was least sensitive. This order was maintained for the vestibular paresis (VP), directional preponderance (DP) and temperature effect (TE) formulas. The magnitude of DP was significantly correlated with the magnitude of spontaneous vestibular nystagmus and both occurred with approximately the same frequency in peripheral and central disorders. There was no reliable way of separating end-organ from VIII nerve or peripheral from central disorders on the basis of the caloric responses. PMID:410351

Baloh, R W; Sills, A W; Honrubia, V

1977-01-01

383

Purchase decision-making is modulated by vestibular stimulation  

PubMed Central

Purchases are driven by consumers’ product preferences and price considerations. Using caloric vestibular stimulation (CVS), we investigated the role of vestibular-affective circuits in purchase decision-making. CVS is an effective noninvasive brain stimulation method, which activates vestibular and overlapping emotional circuits (e.g., the insular cortex and the anterior cingulate cortex (ACC)). Subjects were exposed to CVS and sham stimulation while they performed two purchase decision-making tasks. In Experiment 1 subjects had to decide whether to purchase or not. CVS significantly reduced probability of buying a product. In Experiment 2 subjects had to rate desirability of the products and willingness to pay (WTP) while they were exposed to CVS and sham stimulation. CVS modulated desirability of the products but not WTP. The results suggest that CVS interfered with emotional circuits and thus attenuated the pleasant and rewarding effect of acquisition, which in turn reduced purchase probability. The present findings contribute to the rapidly growing literature on the neural basis of purchase decision-making. PMID:24600365

Preuss, Nora; Mast, Fred W.; Hasler, Gregor

2014-01-01

384

Effects of lesion of the interstitial nucleus of Cajal on vestibular nuclear neurons activated by vertical vestibular stimulation  

Microsoft Academic Search

Summary  1. Experiments were performed in cats anesthetized with nitrous oxide to study the effects of INC lesions on responses of\\u000a vestibular nuclear neurons during sinusoidal rotations of the head in the vertical (pitch) plane. Responses of neurons in\\u000a the INC region were recorded during pitch rotations at 0.15 Hz. A great majority of these neurons did not respond to static

K. Fukushima; K. Takahashi; J. Fukushima; M. Ohno; T. Kimura; M. Kato

1986-01-01

385

Differential diagnosis and management of a patient with peripheral vestibular and central nervous system disorders: a case study  

PubMed Central

Background Clinical examination and management of patients with meningiomas is primarily dependent upon appropriate diagnosis of tumor type and surgical intervention. Physical therapists should be able to identify patients presenting with signs and symptoms suggestive of potential central nervous system (CNS) disorders and refer the patient appropriately. Patient characteristics In this case report, a 52-year-old female was referred to physical therapy after 18 months of unresolved dizziness. Examination Oculomotor examination revealed evidence of peripheral vestibular and potential CNS disorders. The physical therapist referred the patient to a physician who ordered magnetic resonance imaging (MRI). Intervention The patient received five physical therapy sessions while waiting for the MRI which revealed a meningioma. The meningioma was surgically removed and the patient was subsequently relieved of all symptoms. Outcomes Despite the presence of the meningioma, the patient reported improved stability during work-related activities and decreased dizziness as a result of physical therapy intervention pre-operatively. Discussion This case report emphasizes the importance of a physical therapists ability to perform and interpret an oculomotor examination in a patient presenting with signs consistent with peripheral vestibular and CNS disorders. It also demonstrates the role of physical therapy in collaboration with physicians in order to provide appropriate patient care management. PMID:21886427

Trato, Jill; Johnson, Eric G

2010-01-01

386

ERG voltage-gated K+ channels regulate excitability and discharge dynamics of the medial vestibular nucleus neurones  

PubMed Central

The discharge properties of the medial vestibular nucleus neurones (MVNn) critically depend on the activity of several ion channel types. In this study we show, immunohistochemically, that the voltage-gated K+ channels ERG1A, ERG1B, ERG2 and ERG3 are highly expressed within the vestibular nuclei of P10 and P60 mice. The role played by these channels in the spike-generating mechanisms of the MVNn and in temporal information processing was investigated electrophysiologically from mouse brain slices, in vitro, by analysing the spontaneous discharge and the response to square-, ramp- and sinusoid-like intracellular DC current injections in extracellular and whole-cell patch-clamp studies. We show that more than half of the recorded MVNn were responsive to ERG channel block (WAY-123,398, E4031), displaying an increase in spontaneous activity and discharge irregularity. The response to step and ramp current injection was also modified by ERG block showing a reduction of first spike latency, enhancement of discharge rate and reduction of the slow spike-frequency adaptation process. ERG channels influence the interspike slope without affecting the spike shape. Moreover, in response to sinusoid-like current, ERG channel block caused frequency-dependent gain enhancement and phase-lead shift. Taken together, the data demonstrate that ERG channels control the excitability of MVNn, their discharge regularity and probably their resonance properties. PMID:18718985

Pessia, Mauro; Servettini, Ilenio; Panichi, Roberto; Guasti, Leonardo; Grassi, Silvarosa; Arcangeli, Annarosa; Wanke, Enzo; Pettorossi, Vito Enrico

2008-01-01

387

The Effect of Galvanic Vestibular Stimulation on Postural Response of Down Syndrome Individuals on the Seesaw  

ERIC Educational Resources Information Center

In order to better understand the role of the vestibular system in postural adjustments on unstable surfaces, we analyzed the effects of galvanic vestibular stimulation (GVS) on the pattern of muscle activity and joint displacements (ankle knee and hip) of eight intellectually normal participants (control group--CG) and eight control group…

Carvalho, R. L.; Almeida, G. L.

2011-01-01

388

Local effects of nitric oxide on vestibular blood flow in the Mongolian gerbil  

Microsoft Academic Search

There is a paucity of studies regarding the regulation of vestibular blood flow (VBF), despite the possibility that vascular alterations may contribute to specific vestibulopathies. The current experiments used the Mongolian gerbil as an animal model since it provides easy surgical access to the vestibular end-organs and has been previously used for physiologic studies involving inner ear function. VBF changes

J. G. Arenberg; D. A. Komjathy; M. D. Seidman; W. S. Quirk

1997-01-01

389

Vestibular autonomic regulation (including motion sickness and the mechanism of vomiting)  

NASA Technical Reports Server (NTRS)

Autonomic manifestations of vestibular dysfunction and motion sickness are well established in the clinical literature. Recent studies of 'vestibular autonomic regulation' have focused predominantly on autonomic responses to stimulation of the vestibular sense organs in the inner ear. These studies have shown that autonomic responses to vestibular stimulation are regionally selective and have defined a 'vestibulosympathetic reflex' in animal experiments. Outside the realm of experimental preparations, however, the importance of vestibular inputs in autonomic regulation is unclear because controls for secondary factors, such as affective/emotional responses and cardiovascular responses elicited by muscle contraction and regional blood pooling, have been inadequate. Anatomic and physiologic evidence of an extensive convergence of vestibular and autonomic information in the brainstem suggests though that there may be an integrated representation of gravitoinertial acceleration from vestibular, somatic, and visceral receptors for somatic and visceral motor control. In the case of vestibular dysfunction or motion sickness, the unpleasant visceral manifestations (e.g. epigastric discomfort, nausea or vomiting) may contribute to conditioned situational avoidance and the development of agoraphobia.

Balaban, C. D.

1999-01-01

390

Effects of weightlessness on the development of the vestibular apparatus and ocular nystagmus in the rat  

NASA Technical Reports Server (NTRS)

The chronic 2g centrifuge was constructed for testing weightlessness effects on development of vestibular apparatus and ocular nystagmus in the rat. Both the stationary and rotating rail tests were performed. A physiological review is presented on vestibular apparatus, along with a system analysis. Time constants and input threshold level of the system are also considered.

Clark, D. L.

1972-01-01

391

Impaired mental rotation in benign paroxysmal positional vertigo and acute vestibular neuritis  

PubMed Central

Vestibular processing is fundamental to our sense of orientation in space which is a core aspect of the representation of the self. Vestibular information is processed in a large subcortical–cortical neural network. Tasks requiring mental rotations of human bodies in space are known to activate neural regions within this network suggesting that vestibular processing is involved in the control of mental rotation. We studied whether mental rotation is impaired in patients suffering from two different forms of unilateral vestibular disorders (vestibular neuritis – VN – and Benign Paroxysmal positional Vertigo – BPPV) with respect to healthy matched controls (C). We used two mental rotation tasks in which participants were required to: (i) mentally rotate their own body in space (egocentric rotation) thus using vestibular processing to a large extent and (ii) mentally rotate human figures (allocentric rotation) thus using own body representations to a smaller degree. Reaction times and accuracy of responses showed that VN and BPPV patients were impaired in both tasks with respect to C. Significantly, the pattern of results was similar in the three groups suggesting that patients were actually performing the mental rotation without using a different strategy from the control individuals. These results show that dysfunctional vestibular inflow impairs mental rotation of both own body and human figures suggesting that unilateral acute disorders of the peripheral vestibular input massively affect the cerebral processes underlying mental rotations. PMID:24324422

Candidi, Matteo; Micarelli, Alessandro; Viziano, Andrea; Aglioti, Salvatore M.; Minio-Paluello, Ilaria; Alessandrini, Marco

2013-01-01

392

Systematic review of quality of life in the management of vestibular schwannoma  

Microsoft Academic Search

Vestibular schwannoma (VS) is a benign tumour arising from the vestibular component of the vestibulocochlear nerve. Treatment protocols range from observation to microsurgical resection (MS) or radiation therapy using focused delivery techniques: either stereotactic radiosurgery (SRS) or stereotactic radiotherapy (SRT). Most reported outcome measures explore medically orientated results such as extent of resection or facial nerve function and do not

Andrew Gauden; Philip Weir; Graeme Hawthorne; Andrew Kaye

393

Dual task interference during gait in patients with unilateral vestibular disorders  

Microsoft Academic Search

BACKGROUND: Vestibular patients show slower and unsteady gait; they have also been shown to need greater cognitive resources when carrying out balance and cognitive dual tasks (DT). This study investigated DT interference during gait in a middle-aged group of subjects with dizziness and unsteadiness after unilateral vestibular neuronitis and in a healthy control group. METHODS: Fourteen individuals with subacute unilateral

Alberto Nascimbeni; Andrea Gaffuri; Arminio Penno; Mara Tavoni

2010-01-01

394

Multisensory Origin of the Subjective First-Person Perspective: Visual, Tactile, and Vestibular Mechanisms  

PubMed Central

In three experiments we investigated the effects of visuo-tactile and visuo-vestibular conflict about the direction of gravity on three aspects of bodily self-consciousness: self-identification, self-location, and the experienced direction of the first-person perspective. Robotic visuo-tactile stimulation was administered to 78 participants in three experiments. Additionally, we presented participants with a virtual body as seen from an elevated and downward-directed perspective while they were lying supine and were therefore receiving vestibular and postural cues about an upward-directed perspective. Under these conditions, we studied the effects of different degrees of visuo-vestibular conflict, repeated measurements during illusion induction, and the relationship to a classical measure of visuo-vestibular integration. Extending earlier findings on experimentally induced changes in bodily self-consciousness, we show that self-identification does not depend on the experienced direction of the first-person perspective, whereas self-location does. Changes in bodily self-consciousness depend on visual gravitational signals. Individual differences in the experienced direction of first-person perspective correlated with individual differences in visuo-vestibular integration. Our data reveal important contributions of visuo-vestibular gravitational cues to bodily self-consciousness. In particular we show that the experienced direction of the first-person perspective depends on the integration of visual, vestibular, and tactile signals, as well as on individual differences in idiosyncratic visuo-vestibular strategies. PMID:23630611

Pfeiffer, Christian; Lopez, Christophe; Schmutz, Valentin; Duenas, Julio Angel; Martuzzi, Roberto; Blanke, Olaf

2013-01-01

395

[The role of tanakan in the improvement of the effectiveness of vestibular rehabilitation].  

PubMed

The objective of the present study was to estimate the influence of tanakan on the duration of the period needed to achieve vestibular compensation in the patients presenting with peripheral vestibular dizziness in the course of vestibular rehabilitation with the use of the post-urographic system. 72 patients at the age varying from 18 to 42 years (46 women and 26 men) suffering from peripheral vestibular dizziness were treated on an individual basis for the purpose of vestibular rehabilitation 3-5 times per week for a total period of 3-6 weeks. 42 of the 72 patients comprising group 1 were given Tanakan for 3 months at a dose of 40 mg thrice daily, the remaining 30 patients (group 2) continued to receive the vasoactive treatment as prescribed by attending physicians of other medical and diagnostic centres (protocols of their treatment recommended at local medical facilities did not include tanakan therapy). It is concluded that the use of tanakan for the treatment of the patients presenting with peripheral vestibular dizziness accelerates vestibular compensation and reduces the time necessary to achieve vestibular rehabilitation. Moreover, the combined treatment with the application of tanakan makes it possible to decrease the medicamental loading. PMID:25588491

Za?tseva, O V

2014-01-01

396

[Diseases of the peripheral vestibular system : Contribution of ENT medical diagnostics and therapy].  

PubMed

The most common types of vertigo caused by diseases of the peripheral vestibular system are benign paroxysmal positional vertigo (BPPV), Meniere's disease and vestibular neuritis. A thorough examination of the medical history and clinical examination are usually sufficient for the differential diagnostics. Treatment includes differentiated repositioning maneuvers, medicinal treatment and physiotherapy. PMID:25502656

Pabst, F; Machetanz, J; Gerk, U; Simonis, G; Schellong, S

2015-01-01

397

Vestibular evoked myogenic potentials in benign paroxysmal positional vertigo and Meniere’s disease  

Microsoft Academic Search

The objective was to investigate vestibular evoked myogenic potentials (VEMP) in benign paroxysmal positional vertigo (BPPV) and Meniere’s disease, and to determine if this type of testing is valuable for assessing the vestibular system. A prospective controlled clinical study was designed in a tertiary referral center setting. The 62 participants included 17 healthy controls and 45 other subjects selected from

Güzin Akkuzu; Babur Akkuzu; Levent N. Ozluoglu

2006-01-01

398

Directional Preponderance in Patient with Deficit of Vestibular Function: Case Report  

Microsoft Academic Search

To describe a case of a patient with vestibular loss that was evaluated of a sequence vectoeletronystagmography up to one year after the acute vertigo; and discuss the evolution of the initial compensation in the vestibular unilateral loss and the concept of directional preponderance associated to peripheral irritative labyrinth disease. Results: The case report describes a classic central compensation of

Lilian Felipe; Patrícia Cotta Mancini; Denise Utsch Gonçalves

399

Role of somatosensory and vestibular cues in attenuating visually induced human postural sway  

NASA Technical Reports Server (NTRS)

The purpose of this study was to determine the contribution of visual, vestibular, and somatosensory cues to the maintenance of stance in humans. Postural sway was induced by full-field, sinusoidal visual surround rotations about an axis at the level of the ankle joints. The influences of vestibular and somatosensory cues were characterized by comparing postural sway in normal and bilateral vestibular absent subjects in conditions that provided either accurate or inaccurate somatosensory orientation information. In normal subjects, the amplitude of visually induced sway reached a saturation level as stimulus amplitude increased. The saturation amplitude decreased with increasing stimulus frequency. No saturation phenomena were observed in subjects with vestibular loss, implying that vestibular cues were responsible for the saturation phenomenon. For visually induced sways below the saturation level, the stimulus-response curves for both normal subjects and subjects experiencing vestibular loss were nearly identical, implying (1) that normal subjects were not using vestibular information to attenuate their visually induced sway, possibly because sway was below a vestibular-related threshold level, and (2) that subjects with vestibular loss did not utilize visual cues to a greater extent than normal subjects; that is, a fundamental change in visual system "gain" was not used to compensate for a vestibular deficit. An unexpected finding was that the amplitude of body sway induced by visual surround motion could be almost 3 times greater than the amplitude of the visual stimulus in normal subjects and subjects with vestibular loss. This occurred in conditions where somatosensory cues were inaccurate and at low stimulus amplitudes. A control system model of visually induced postural sway was developed to explain this finding. For both subject groups, the amplitude of visually induced sway was smaller by a factor of about 4 in tests where somatosensory cues provided accurate versus inaccurate orientation information. This implied (1) that the subjects experiencing vestibular loss did not utilize somatosensory cues to a greater extent than normal subjects; that is, changes in somatosensory system "gain" were not used to compensate for a vestibular deficit, and (2) that the threshold for the use of vestibular cues in normal subjects was apparently lower in test conditions where somatosensory cues were providing accurate orientation information.

Peterka, R. J.; Benolken, M. S.

1995-01-01

400

Long-term effects of vestibular compensation on balance control and sensory organisation after unilateral deafferentation due to vestibular schwannoma surgery  

Microsoft Academic Search

The time-course of central adaptive mechanisms after vestibular schwannoma surgical removal allows, 3 months after surgery (middle term), a satisfactory recovery of balance control. However, the long-term evolution of postural control beyond the end of usual medical follow-up remains unknown. This longitudinal prospective study aimed to assess the long-term effects of vestibular compensation on balance control and sensory organisation in

Cécile Parietti-Winkler; Gérome C Gauchard; Claude Simon; Philippe P Perrin

2010-01-01

401

Enlarged vestibular aqueduct (EVA) related with recurrent benign paroxysmal positional vertigo (BPPV).  

PubMed

The vestibular aqueduct is a bony canal related to the bony labyrinth of the inner ear and represents the non-sensory components of the endolymph-filled, closed, membranous labyrinth. The association of congenital sensorineural hearing loss with a large or enlarged vestibular aqueduct is well known as the large vestibular aqueduct syndrome (LVAS). The enlarged VA (EVA) comprises abnormalities not only in the structure of the inner ear, but also in the physiology of the auditory and vestibular systems. The clinical picture of this clinical entity is variable [Yetiser S, Kertment M, Ozkaptan Y. Vestibular disturbance in patients with Large Vestibular Aqueduct Syndrome (LVAS). Acta Otolaryngol (StochK) 1999;119: 641-646]. Signs and symptoms of the auditory impairment are more commonly described in the literature: hearing loss ranges from mild to profound, arising from fluctuating to stepwise progressive or sudden. Vestibular disturbances, ranging from mild imbalance to episodic vertigo, are rarely described in the literature. Benign paroxysmal positional vertigo (BPPV) is a labyrinthine disorder with a typical behavior: intense crises of rotational vertigo induced by postural changes of the head, with short duration and usually good responsiveness to rehabilitative maneuvers. These maneuvers are effective in about 80% of patients with BPPV. BPPV often recurs. About 1/3 of patients have a recurrence in the first year after treatment, and by five years, about half of all patients have a recurrence. Vestibular aqueduct has been demonstrated by conventional tomography and computed tomography (CT), however, CT scans cannot show the membranous labyrinth itself. On MR images it is not the vestibular aqueduct that is visualized but its contents, the endolymphatic duct and sac, and can show the abnormalities of the fluid spaces related to the membranous labyrinth. It is proposed that recurrent benign paroxysmal positional vertigo (BPPV) is related with volumetric abnormalities of vestibular aqueduct. This verifiable hypothesis tries to define this rapport and explore new diagnostic and therapeutic possibilities. PMID:17590526

Manzari, Leonardo

2008-01-01

402

Development and Function of the Mouse Vestibular System in the Absence of Gravity Perception  

NASA Technical Reports Server (NTRS)

The hypothesis that was tested in this research was that the absence of gravity perception, such as would occur in space, would affect the development and function of the vestibular and central nervous systems. Further, we postulated that these effects would be more significant at specific stages of post-natal development of the animal. We also proposed the use of molecular genetic approaches that would provide important information as to the hierarchy of gene function during the development and subsequent function of the vestibular system. The tilted (tlt) mutant mouse has been characterized as lacking the ability to provide sensory input to the gravity receptors. The tlt/tlt mutant mice were a particularly attractive model for the study of vestibular function since the primary defect was limited to the receptor part of the vestibular system, and there were no detectable abnormal phenotypes in other organ systems. The goal of the proposed studies was to assess immediate and delayed effects of the lack of gravity perception on the vestibular system. Particular attention was paid to characterizing primarily affected periods of vestibular morphogenesis, and to identifying downstream genetic pathways that are altered in the CNS of the tlt/tlt mutant mouse. The specific aims were: (1) to characterize the postnatal morphogenesis of the CNS in the tlt mutant mouse, using detailed morphometric analysis of isolated vestibular ganglia and brain tissue at different stages of postnatal development and assessment of apoptotic cell death; (2) to examine the expression of selected genes implicated by mutational analysis to be important in vestibular development or function by in situ hybridization or immunohistochemistry in the mutant mice; and (3) to identify other genes involved in vestibular development and function, using differential cloning strategies to isolate genes whose expression is changed in the mutant versus normal vestibular system.

Wolgemuth, Debra J.

2005-01-01

403

Effects of vestibular loss on head stabilization in response to head and body perturbations  

NASA Technical Reports Server (NTRS)

Control of head position during postural responses is important to facilitate both the interpretation of vestibular signals and the stabilization of gaze. In these experiments, we compared head stabilization for two different postural tasks: 1) in response to perturbations at the head, and 2) in response to perturbations induced at the support surface, which perturb both body and head position. To determine whether normal vestibular function is necessary for head stabilization in these two tasks, responses to forward and backward mechanical perturbations of the head and body were compared for 13 normal subjects and 4 patients with profound bilateral vestibular loss (two with vestibular loss in adulthood and two in infancy). Normal subjects showed little neck muscle activity for body perturbations, but large, early activations in both neck extensors and flexors for head perturbations. In contrast, vestibular patients showed excessive neck muscle activation for body perturbations and reduced or absent neck muscle activity for head perturbations. Patients with vestibular loss in adulthood also showed increased head acceleration in response to both head and body perturbations, but patients with vestibular loss in infancy showed more normal head accelerations. For body perturbations, the differences in head acceleration between patients and normals were greater for later head acceleration peaks, indicating poor head control during the execution of the postural response. Trunk angle changes were also higher in the patients for forward body perturbations, indicating that poorer control of trunk position could have contributed to their poorer head stabilization. These results indicate that the vestibular system plays an important role in head and trunk stabilization for both head and body perturbations. However, the more normal head accelerations of the patients with infant vestibular loss also indicate that other mechanisms, possibly involving neck reflexes, can at least partially substitute for the vestibular system to provide head and trunk stabilization.

Shupert, C. L.; Horak, F. B.; Peterson, B. W. (Principal Investigator)

1996-01-01

404

Dizziness and Imbalance in the Elderly: Age-related Decline in the Vestibular System  

PubMed Central

Dizziness and imbalance are amongst the most common complaints in older people, and are a growing public health concern since they put older people at a significantly higher risk of falling. Although the causes of dizziness in older people are multifactorial, peripheral vestibular dysfunction is one of the most frequent causes. Benign paroxysmal positional vertigo is the most frequent form of vestibular dysfunction in the elderly, followed by Meniere’s disease. Every factor associated with the maintenance of postural stability deteriorates during aging. Age-related deterioration of peripheral vestibular function has been demonstrated through quantitative measurements of the vestibulo-ocular reflex with rotational testing and of the vestibulo-collic reflex with testing of vestibular evoked myogenic potentials. Age-related decline of vestibular function has been shown to correlate with the age-related decrease in the number of vestibular hair cells and neurons. The mechanism of age-related cellular loss in the vestibular endorgan is unclear, but it is thought that genetic predisposition and cumulative effect of oxidative stress may both play an important role. Since the causes of dizziness in older people are multi-factorial, management of this disease should be customized according to the etiologies of each individual. Vestibular rehabilitation is found to be effective in treating both unilateral and bilateral vestibular dysfunction. Various prosthetic devices have also been developed to improve postural balance in older people. Although there have been no medical treatments improving age-related vestibular dysfunction, new medical treatments such as mitochondrial antioxidants or caloric restriction, which have been effective in preventing age-related hearing loss, should be ienvestigated in the future.

Iwasaki, Shinichi; Yamasoba, Tatsuya

2015-01-01

405

Responses of central vestibular neurons to sinusoidal yaw rotation in compensated macaques after unilateral labyrinthectomy  

PubMed Central

After vestibular labyrinth injury, behavioral measures of vestibular function partially recover through the process of vestibular compensation. The present study was performed to improve our understanding of the physiology of macaque vestibular nucleus neurons in the compensated state (>6 wk) after unilateral labyrinthectomy (UL). The responses of neurons to sinusoidal yaw rotation at a series of frequencies (0.1–2.0 Hz) and peak velocities (7.5–210°/s) were examined to determine how the behavior of these cells differed from those in animals with intact labyrinths. The sensitivity of neurons responding to ipsilateral rotation (type I) did not differ between the intact and injured sides after UL, although this sensitivity was lower bilaterally after lesion than before lesion. The sensitivity of neurons that increase firing with contralateral rotation (type II) was higher ipsilateral to the UL than before lesion or in the nucleus contralateral to the UL. UL did not increase asymmetry in the responses of individual type I or II neurons to ipsilateral vs. contralateral rotation, nor does it change the power law relationship between neuronal firing and level of stimulation. Increased sensitivities of contralesional type I neurons to the remaining vestibular nerve input and increased efficacy of inhibitory vestibular commissures projecting to the ipsilesional vestibular nucleus appear to be responsible for recovery of dynamic function of central vestibular neurons in compensated animals. The portion of type I neurons on the ipsilesional side is reduced in compensated animals, which likely accounts for the asymmetries in vestibular reflexes and perception that characterize vestibular function after UL. PMID:23864379

Wei, Min

2013-01-01

406

The effect of clinorotation on vestibular compensation in upside-down swimming catfish.  

PubMed

Upside-down swimming catfish Synodontis nigriventris can keep upside-down swimming posture stably under pseudo-microgravity generated by clinostat. When the vestibular organ is unilaterally ablated, the operated S. nigriventris shows disturbed swimming postures under the clinorotation condition. However, about 1 month after the operation, unilateral vestibular organ-ablated S. nigriventris shows stable upside-down swimming posture under the condition (vestibular compensation). In contrast, a closely related upside-up swimming catfish Synodontis multipunctatus belonging to same Synodontis family can not keep stable swimming postures under the clinorotation conditions. In this study, we examined the effect of continuous clinorotation on vestibular compensation in intact and unilateral vestibular organ-ablated Synodontis nigriventris and Synodontis multipunctatus. After the exposure to continuous clinorotation, the postures of the catfish were observed under microgravity provided by parabolic flights of an aircraft. Unilateral vestibular organ-ablated S. nigriventris which had been exposed to continuous clinorotation showed stable swimming postures and did not show dorsal light reaction (DLR) under microgravity. This postural control pattern of the operated catfish was similar to that of intact catfish. Intact and unilateral vestibular organ-ablated S. multipunctatus showed DLR during microgravity. Our results confirmed that S. nigriventris has a novel balance sensation which is not affected by microgravity. DLR seems not to play an important role in postural control. It remains unclear that the continuous clinorotation effects on vestibular compensation because we could not keep used unilateral vestibular organ-ablated fish alive under continuous clinorotation for uninterrupted 25 days. This study suggests that space flight experiments are required to explore whether gravity information is essential for vestibular compensation. PMID:14676355

Ohnishi, Ken; Okamoto, Noritomo; Yamanaka, Toshiaki; Takahashi, Akihisa; Hosoi, Hiroshi; Ohnishi, Takeo

2003-10-01

407

The Modified Ampullar Approach for Vestibular Implant Surgery: Feasibility and Its First Application in a Human with a Long-Term Vestibular Loss  

PubMed Central

Objective: To assess, for the first time in a human with a long-term vestibular loss, a modified approach to the ampullae and the feasibility of evoking a VOR by ampullar stimulation. Materials and methods: Peroperative stimulation of the ampullae, using the ampullar approach, was performed under full anesthesia during cochlear implantation in a 21-year-old female patient, who had experienced bilateral vestibular areflexia and sensorineural hearing loss for almost 20?years. Results: The modified ampullar approach was performed successfully with as minimally invasive surgery as possible. Ampullar stimulation evoked eye movements containing vectors congruent with the stimulated canal. As expected, the preliminary electrophysiological data were influenced by the general anesthesia, which resulted in current spread and reduced maximum amplitudes of eye movement. Nevertheless, they confirm the feasibility of ampullar stimulation. Conclusion: The modified ampullar approach provides safe access to the ampullae using as minimally invasive surgery as possible. For the first time in a human with long-term bilateral vestibular areflexia, it is shown that the VOR can be evoked by ampullar stimulation, even when there has been no vestibular function for almost 20?years. This approach should be considered in vestibular surgery, as it provides safe access to one of the most favorable stimulus locations for development of a vestibular implant. PMID:22363317

van de Berg, Raymond; Guinand, Nils; Guyot, Jean-Philippe; Kingma, Herman; Stokroos, Robert J.

2012-01-01

408

Yaw and pitch visual-vestibular interaction in weightlessness  

NASA Technical Reports Server (NTRS)

Both yaw and pitch visual-vestibular interactions at two separate frequencies of chair rotation (0.2 and 0.8 Hz) in combination with a single velocity of optokinetic stimulus (36 degrees/s) were used to investigate the effects of sustained weightlessness on neural strategies adopted by astronaut subjects to cope with the stimulus rearrangement of spaceflight. Pitch and yaw oscillation in darkness at 0.2 and 0.8 Hz without optokinetic stimulation, and constant velocity linear optokinetic stimulation at 18, 36, and 54 degrees/s presented relative to the head with the subject stationary, were used as controls for the visual-vestibular interactions. The results following 8 days of space flight showed no significant changes in: (1) either the horizontal and vertical vestibulo-ocular reflex (VOR) gain, phase, or bias; (2) the yaw visual-vestibular response (VVR); or (3) the horizontal or vertical optokinetic (OKN) slow phase velocity (SPV). However, significant changes were observed: (1) when during pitch VVR at 0.2 Hz late inflight, the contribution of the optokinetic input to the combined oculomotor response was smaller than during the stationary OKN SPV measurements, followed by an increased contribution during the immediate postflight testing; and (2) when during pitch VVR at 0.8 Hz, the component of the combined oculomotor response due to the underlying vertical VOR was more efficiently suppressed early inflight and less suppressed immediately postflight compared with preflight observations. The larger OKN response during pitch VVR at 0.2 Hz and the better suppression of VOR during pitch VVR at 0.8 Hz postflight are presumably due to the increased role of vision early inflight and immediately after spaceflight, as previously observed in various studies. These results suggest that the subjects adopted a neural strategy to structure their spatial orientation in weightlessness by reweighting visual, otolith, and perhaps tactile/somatic signals.

Clement, G.; Wood, S. J.; Reschke, M. F.; Berthoz, A.; Igarashi, M.

1999-01-01

409

Dynamic visual acuity testing for screening patients with vestibular impairments  

PubMed Central

Dynamic visual acuity (DVA) may be a useful indicator of the function of the vestibulo-ocular reflex (VOR) but most DVA tests involve active head motion in the yaw plane. During gait the passive, vertical VOR may be more relevant and passive testing would be less likely to elicit compensatory strategies. The goal of this study was to determine if testing dynamic visual acuity during passive vertical motion of the subject would differentiate normal subjects from patients with known vestibular disorder