Sample records for vestibular stochastic resonance

  1. Stochastic Resonance

    NASA Astrophysics Data System (ADS)

    McDonnell, Mark D.; Stocks, Nigel G.; Pearce, Charles E. M.; Abbott, Derek

    2012-10-01

    Preface; 1. Introduction and motivation; 2. Stochastic resonance: its definitions, history and debates; 3. Stochastic quantization; 4. Suprathreshold stochastic resonance: encoding; 5. Suprathreshold stochastic resonance: large N encoding; 6. Suprathreshold stochastic resonance: decoding; 7. Suprathreshold stochastic resonance: large N decoding; 8. Optimal stochastic quantization; 9. SSR, neural coding, and performance tradeoffs; 10. Stochastic resonance in the auditory system; 11. The future of stochastic resonance and suprathreshold stochastic resonance; Appendices; References; Index.

  2. Improving Sensorimotor Function Using Stochastic Vestibular Stimulation

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

  3. Frequency response of human vestibular reflexes characterized by stochastic stimuli.

    PubMed

    Dakin, Christopher J; Son, Gregory M Lee; Inglis, J Timothy; Blouin, Jean-Sébastien

    2007-09-15

    Stochastic vestibular stimulation (SVS) can be used to study the postural responses to unpredictable vestibular perturbations. The present study seeks to determine if stochastic vestibular stimulation elicits lower limb muscular responses and to estimate the frequency characteristics of these vestibulo-motor responses in humans. Fourteen healthy subjects were exposed to unpredictable galvanic currents applied on their mastoid processes while quietly standing (+/-3 mA, 0-50 Hz). The current amplitude and stimulation configuration as well as the subject's head position relative to their feet were manipulated in order to determine that: (1) the muscle responses evoked by stochastic currents are dependent on the amplitude of the current, (2) the muscle responses evoked by stochastic currents are specific to the percutaneous stimulation of vestibular afferents and (3) the lower limb muscle responses exhibit polarity changes with different head positions as previously described for square-wave galvanic vestibular stimulation (GVS) pulses. Our results revealed significant coherence (between 0 and 20 Hz) and cumulant density functions (peak responses at 65 and 103 ms) between SVS and the lower limbs' postural muscle activity. The polarity of the cumulant density functions corresponded to that of the reflexes elicited by square-wave GVS pulses. The SVS-muscle activity coherence and time cumulant functions were modulated by current amplitude, electrode position and head orientation with respect to the subject's feet. These findings strongly support the vestibular origin of the lower limb muscles evoked by SVS. In addition, specific frequency bandwidths in the stochastic vestibular signal contributed to the early (12-20 Hz) and late components (2-10 Hz) of the SVS-evoked muscular responses. These frequency-dependent SVS-evoked muscle responses support the view that the biphasic muscle response is conveyed by two distinct physiological processes. PMID:17640935

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

    NASA Technical Reports Server (NTRS)

    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

    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.

  5. The effects of stochastic galvanic vestibular stimulation on human postural sway.

    PubMed

    Pavlik, A E; Inglis, J T; Lauk, M; Oddsson, L; Collins, J J

    1999-02-01

    Galvanic vestibular stimulation serves to modulate the continuous firing level of the peripheral vestibular afferents. It has been shown that the application of sinusoidally varying, bipolar galvanic currents to the vestibular system can lead to sinusoidally varying postural sway. Our objective was to test the hypothesis that stochastic galvanic vestibular stimulation can lead to coherent stochastic postural sway. Bipolar binaural stochastic galvanic vestibular stimulation was applied to nine healthy young subjects. Three different stochastic vestibular stimulation signals, each with a different frequency content (0-1 Hz, 1-2 Hz, and 0-2 Hz), were used. The stimulation level (range 0.4-1.5 mA, peak to peak) was determined on an individual basis. Twenty 60-s trials were conducted on each subject - 15 stimulation trials (5 trials with each stimulation signal) and 5 control (no stimulation) trials. During the trials, subjects stood in a relaxed, upright position with their head facing forward. Postural sway was evaluated by using a force platform to measure the displacements of the center of pressure (COP) under each subject's feet. Cross-spectral measures were used to quantify the relationship between the applied stimulus and the resulting COP time series. We found significant coherency between the stochastic vestibular stimulation signal and the resulting mediolateral COP time series in the majority of trials in 8 of the 9 subjects tested. The coherency results for each stimulation signal were reproducible from trial to trial, and the highest degree of coherency was found for the 1- to 2-Hz stochastic vestibular stimulation signal. In general, for the nine subjects tested, we did not find consistent significant coherency between the stochastic vestibular stimulation signals and the anteroposterior COP time series. This work demonstrates that, in subjects who are facing forward, bipolar binaural stochastic galvanic stimulation of the vestibular system leads to coherent stochastic mediolateral postural sway, but it does not lead to coherent stochastic anteroposterior postural sway. Our finding that the coherency was highest for the 1- to 2-Hz stochastic vestibular stimulation signal may be due to the intrinsic dynamics of the quasi-static postural control system. In particular, it may result from the effects of the vestibular stimulus simply being superimposed upon the quiet-standing COP displacements. By utilizing stochastic stimulation signals, we ensured that the subjects could not predict a change in the vestibular stimulus. Thus, our findings indicate that subjects can act as "responders" to galvanic vestibular stimulation. PMID:9989432

  6. Resonance with Stochastic Time

    NASA Astrophysics Data System (ADS)

    Ohira, Toru

    2010-06-01

    We introduce a resonant phenomenon using a model incorporating delay (temporal non-locality) and stochastic time (temporal stochasticity). Although this model is a very simple linear dynamical differential equation, the addition of these elements makes it very rich. As an illustrative example, we describe a human stick balancing experiment that includes added fluctuations. We discuss how these concepts of temporal non-locality and stochasticity could play a role in characterizing biological and physiological systems, as well as in physics.

  7. Quantum stochastic resonance

    SciTech Connect

    Loefstedt, R.; Coppersmith, S.N. (AT T Bell Laboratories, Murray Hill, New Jersey 07974 (United States))

    1994-03-28

    We demonstrate that stochastic resonance, where an increase in the noise acting on a nonlinear dynamical system increases the signal-to-noise ratio describing the response to periodic driving, can occur in quantum systems as well as classical ones. We show that quantum stochastic resonance can be observed experimentally by measuring conductance fluctuations in mesoscopic metals and describe the experimental parameters for which it occurs.

  8. Stochastic resonance in a stochastic bistable system

    NASA Astrophysics Data System (ADS)

    Ai, Bao-quan; Liu, Liang-gang

    2007-02-01

    Stochastic resonance (SR) in a bistable system is investigated in the presence of a stochastic potential. The signal-to-noise ratio (SNR) is calculated by using the two-state approach. It is found that there exist transitions in SNR from one peak to two peaks, then to one peak again and finally to no peak on increasing the intensity of the stochastic potential. An optimal stochastic potential may induce a doubly stochastic resonance (DSR). When the intensity of the stochastic potential is too large, the effect of the double well diminishes and the SR phenomenon disappears.

  9. Doubly stochastic resonance

    PubMed

    Zaikin; Kurths; Schimansky-Geier

    2000-07-10

    We report the effect of doubly stochastic resonance which appears in nonlinear extended systems if the influence of noise is twofold: A multiplicative noise induces bimodality of the mean field of the coupled network and an independent additive noise governs the dynamic behavior in response to small periodic driving. For optimally selected values of the additive noise intensity stochastic resonance is observed, which is manifested by a maximal coherence between the dynamics of the mean field and the periodic input. Numerical simulations of the signal-to-noise ratio and theoretical results from an effective two state model are in good quantitative agreement. PMID:10991250

  10. Double entropic stochastic resonance

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

    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.

  11. Energetics of stochastic resonance

    NASA Astrophysics Data System (ADS)

    Jung, Peter; Marchesoni, Fabio

    2011-12-01

    In this paper, we discuss the motion of a Brownian particle in a double-well potential driven by a periodic force in terms of energies delivered by the periodic and the noise forces and energy dissipated into the viscous environment. It is shown that, while the power delivered by the periodic force to the Brownian particle is controlled by the strength of the noise, the power delivered by the noise itself is independent of the amplitude and frequency of the periodic force. The implications of this result for the mechanism of stochastic resonance in an equilibrium system is that it is not energy from the noise force which enhances a small periodic force, but rather an increase of energy delivered by the periodic force, regulated by the strength of the noise. We further re-evaluate the frequency dependence of stochastic resonance in terms of energetic terms including efficiency.

  12. Energetics of stochastic resonance.

    PubMed

    Jung, Peter; Marchesoni, Fabio

    2011-12-01

    In this paper, we discuss the motion of a Brownian particle in a double-well potential driven by a periodic force in terms of energies delivered by the periodic and the noise forces and energy dissipated into the viscous environment. It is shown that, while the power delivered by the periodic force to the Brownian particle is controlled by the strength of the noise, the power delivered by the noise itself is independent of the amplitude and frequency of the periodic force. The implications of this result for the mechanism of stochastic resonance in an equilibrium system is that it is not energy from the noise force which enhances a small periodic force, but rather an increase of energy delivered by the periodic force, regulated by the strength of the noise. We further re-evaluate the frequency dependence of stochastic resonance in terms of energetic terms including efficiency. PMID:22225390

  13. Stochastic Resonance: from climate to biology

    E-print Network

    Roberto Benzi

    2007-02-05

    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.

  14. Stochastic resonance in electrical circuits. I. Conventional stochastic resonance

    Microsoft Academic Search

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

    1999-01-01

    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

  15. Stochastic Resonance and Information Processing

    NASA Astrophysics Data System (ADS)

    Nicolis, C.

    2014-12-01

    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.

  16. Brownian motors and stochastic resonance

    NASA Astrophysics Data System (ADS)

    Mateos, José L.; Alatriste, Fernando R.

    2011-12-01

    We study the transport properties for a walker on a ratchet potential. The walker consists of two particles coupled by a bistable potential that allow the interchange of the order of the particles while moving through a one-dimensional asymmetric periodic ratchet potential. We consider the stochastic dynamics of the walker on a ratchet with an external periodic forcing, in the overdamped case. The coupling of the two particles corresponds to a single effective particle, describing the internal degree of freedom, in a bistable potential. This double-well potential is subjected to both a periodic forcing and noise and therefore is able to provide a realization of the phenomenon of stochastic resonance. The main result is that there is an optimal amount of noise where the amplitude of the periodic response of the system is maximum, a signal of stochastic resonance, and that precisely for this optimal noise, the average velocity of the walker is maximal, implying a strong link between stochastic resonance and the ratchet effect.

  17. Brownian motors and stochastic resonance.

    PubMed

    Mateos, José L; Alatriste, Fernando R

    2011-12-01

    We study the transport properties for a walker on a ratchet potential. The walker consists of two particles coupled by a bistable potential that allow the interchange of the order of the particles while moving through a one-dimensional asymmetric periodic ratchet potential. We consider the stochastic dynamics of the walker on a ratchet with an external periodic forcing, in the overdamped case. The coupling of the two particles corresponds to a single effective particle, describing the internal degree of freedom, in a bistable potential. This double-well potential is subjected to both a periodic forcing and noise and therefore is able to provide a realization of the phenomenon of stochastic resonance. The main result is that there is an optimal amount of noise where the amplitude of the periodic response of the system is maximum, a signal of stochastic resonance, and that precisely for this optimal noise, the average velocity of the walker is maximal, implying a strong link between stochastic resonance and the ratchet effect. PMID:22225377

  18. Pitch sensation involves stochastic resonance.

    PubMed

    Martignoli, Stefan; Gomez, Florian; Stoop, Ruedi

    2013-01-01

    Pitch is a complex hearing phenomenon that results from elicited and self-generated cochlear vibrations. Read-off vibrational information is relayed higher up the auditory pathway, where it is then condensed into pitch sensation. How this can adequately be described in terms of physics has largely remained an open question. We have developed a peripheral hearing system (in hardware and software) that reproduces with great accuracy all salient pitch features known from biophysical and psychoacoustic experiments. At the level of the auditory nerve, the system exploits stochastic resonance to achieve this performance, which may explain the large amount of noise observed in the working auditory nerve. PMID:24045830

  19. Molecular sorting by stochastic resonance

    PubMed Central

    Alcor, Damien; Croquette, Vincent; Jullien, Ludovic; Lemarchand, Annie

    2004-01-01

    To sort a targeted species from a mixture, we introduce a procedure that relies on the enhancement of its effective diffusion coefficient. We use the formation of a host–guest complex between ?-cyclodextrin and a dye to evidence the dye dispersion when the medium is submitted to an oscillating field. In particular, we demonstrate that the effective diffusion coefficient of the dye may be increased far beyond its intrinsic value by tuning the driving field frequency in the stochastic resonance regime. We use this effect to selectively sort from a mixture a dye that is addressed by its rate constants for association with ?-cyclodextrin. PMID:15155904

  20. Soft threshold stochastic resonance Priscilla E. Greenwood

    E-print Network

    Mueller, Uschi

    Soft threshold stochastic resonance Priscilla E. Greenwood Arizona State University Ursula U. M¨uller Universit¨at Bremen Lawrence M. Ward University of British Columbia Abstract Soft thresholds are ubiquitous. Which soft threshold functions produce (threshold) stochastic resonance remains a question. The answer

  1. Stochastic resonant memory storage device.

    PubMed

    Carusela, M F; Perazzo, R P; Romanelli, L

    2001-09-01

    We show that an extended system operating in the regime of stochastic resonance can act as a short-term memory device. The system under study is a ring of overdamped bistable oscillators coupled directionally, being each also subject to an external source of Gaussian white noise (the noise sources are independent). A single oscillator is driven by an external periodic force, assumed to act only over the time that the signal takes to traverse the whole ring. A traveling wave is then found to be transmitted several times along the ring with a small damping, provided that the driven oscillator operates in a regime close to stochastic resonance. If noise is suppressed from any oscillator of the chain, the traveling wave is immediately damped. The ring is thus found to act as a short-term memory device in which the stored information (one bit, corresponding to the presence or absence of the external driving) is sustained by noise during a characteristic time T(mem). PMID:11580313

  2. Enlarged Vestibular Aqueduct Syndrome (EVAS)

    MedlinePLUS

    ... Vestibular Disorders Diagnosis & Treatment Types of Vestibular Disorders Acoustic Neuroma/Vestibular Schwannoma Age-related dizziness and imbalance ... For radiologic assessment, fast spin-echo magnetic resonance imaging (MRI) is generally considered to be the most ...

  3. New measures and effects of stochastic resonance 

    E-print Network

    Sethuraman, Swaminathan

    2005-11-01

    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...

  4. Stochastic resonance: nonrobust and robust tuning notions #

    E-print Network

    Imkeller, Peter

    A30, 37N10 Keywords: Stochastic resonance, spectral gap, stochastic di#erential equation, energy periodicity with a measure of quality of tuning. Notions of quality of tuning widely used in physics such as the spectral power amplification or the signal­to­noise ratio depend on the spectral properties of the averaged

  5. Double stochastic resonance over an asymmetric barrier

    NASA Astrophysics Data System (ADS)

    Borromeo, M.; Marchesoni, F.

    2010-01-01

    In a recent experiment [Müller , Phys. Rev. A 79, 031804(R) (2009)] reported a splitting of the stochastic resonance peak, which they attributed to the asymmetry of an effective double-well restoring potential in their optomechanical read-out device. We show here that such an effect, though smaller than reported, is indeed consistent with a characterization of stochastic resonance as a synchronization phenomenon, while it proves elusive in terms of spectral quantifiers.

  6. Cortical and subcortical vestibular response to caloric stimulation detected by functional magnetic resonance imaging.

    PubMed

    Suzuki, M; Kitano, H; Ito, R; Kitanishi, T; Yazawa, Y; Ogawa, T; Shiino, A; Kitajima, K

    2001-12-01

    The posterior insula, central sulcus, and inferior parietal lobule including the intraparietal sulcus have been considered the vestibular cortex based on functional brain mapping in humans as well as experiments in lower primates. The same regions receive optokinetic, visual, and proprioceptive projections. We examined the cortical and subcortical projection of vestibular activity with visual and proprioceptive input eliminated during caloric stimulation (CS), using functional magnetic resonance imaging (fMRI). Single-shot gradient-echo echoplanar image (EPI) volumes were sensitive to BOLD contrast in oblique orientation. We adopted a pharmacokinetic model for analysis of imaging data from 10 subjects as a group. The insular gyrus, intraparietal sulcus, superior temporal gyrus, hippocampus, cingulate gyrus, and thalamus showed activation by CS. Cortical and subcortical activation during CS in the present study was observed within regions less precisely delineated by other methods. As intraparietal sulcus activation showed right hemispheric dominance, this region may have an oculomotor projection as well as the vestibular input. PMID:11689304

  7. Signal amplification in a nanomechanical Duffing resonator via stochastic resonance

    NASA Astrophysics Data System (ADS)

    Almog, Ronen; Zaitsev, Stav; Shtempluck, Oleg; Buks, Eyal

    2007-01-01

    The authors experimentally study stochastic resonance in a nonlinear bistable nanomechanical doubly clamped beam resonator, which is capacitively excited by an adjacent gate electrode. The resonator is tuned to its bistability region by an intense pump near a point of equal transition rates between its two metastable states. The pump is amplitude modulated, inducing modulation of the activation barrier between the states. When noise is added to the excitation, resonator's displacement exhibits noise dependent amplification of the modulation signal. They measure resonator's response in the time and frequency domains, the spectral amplification, and the statistical distribution of the jump time.

  8. Simple electronic circuit model for doubly stochastic resonance.

    PubMed

    Zaikin, A A; Murali, K; Kurths, J

    2001-02-01

    We have recently reported the phenomenon of doubly stochastic resonance [Phys. Rev. Lett. 85, 227 (2000)], a synthesis of noise-induced transition and stochastic resonance. The essential feature of this phenomenon is that multiplicative noise induces a bimodality and additive noise causes stochastic resonance behavior in the induced structure. In the present paper we outline possible applications of this effect and design a simple lattice of electronic circuits for the experimental realization of doubly stochastic resonance. PMID:11308450

  9. Stochastic resonance in the Bénard system

    NASA Astrophysics Data System (ADS)

    Barbini, Leonardo; Bordi, Isabella; Fraedrich, Klaus

    2014-09-01

    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.

  10. Stochastic resonance: A residence time approach

    SciTech Connect

    Gammaitoni, L. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06100 Perugia (Italy)]|[Dipartimento di Fisica, Universita` di Perugia, I-06100 Perugia (Italy); Marchesoni, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06100 Perugia (Italy)]|[Dipartimento di Fisica, Universita` di Camerino, I-62032 Camerino (Italy); Menichella Saetta, E.; Santucci, S. [Dipartimento di Fisica, Universita` di Perugia, I-06100 Perugia (Italy)

    1996-06-01

    The Stochastic Resonance phenomenon is described as a synchronization process between periodic signals and the random response in bistable systems. The residence time approach as a useful tool in characterizing hidden periodicities is discussed. {copyright} {ital 1996 American Institute of Physics.}

  11. Transition times and stochastic resonance for multidimensional

    E-print Network

    Transition times and stochastic resonance for multidimensional diffusions with time periodic drift- turbation: a slow external periodic perturbation of period T and a small Gaussian random perturbation the nonlinear func- tion b(q, T ) describes the force associated with a double well potential possessing two

  12. Stochastic resonance in binocular rivalry

    Microsoft Academic Search

    Yee-Joon Kim; Marcia Grabowecky; Satoru Suzuki

    2006-01-01

    When a different image is presented to each eye, visual awareness spontaneously alternates between the two images—a phenom- enon 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

  13. Cochlear Implant Coding with Stochastic Beamforming and Suprathreshold Stochastic Resonance

    Microsoft Academic Search

    Nigel G. Stocks; Boris Shulgin; Stephen D. Holmes; Alexander Nikitin; Robert P. Morse

    Cochlear implants are prosthetic devices used to provide hearing to people who would otherwise be profoundly deaf. The deliberate\\u000a addition of noise to the electrode signals can in principle increase the amount of information transmitted via an effect termed\\u000a suprathreshold stochastic resonance (SSR). However, for SSR to occur the noise must be added in such a way so as to

  14. Pinning noise-induced stochastic resonance.

    PubMed

    Tang, Yang; Gao, Huijun; Zou, Wei; Kurths, Jürgen

    2013-06-01

    This paper proposes the concept of pinning noise and then investigates the phenomenon of stochastic resonance of coupled complex systems driven by pinning noise, where the noise has an ?-stable distribution. Two kinds of pinning noise are taken into account: partial noise and switching noise. In particular, we establish a connection between switching noise and global noise when Gaussian noise is considered. It is shown that switching noise can not only achieve a stronger resonance effect, but it is also more robust to induce the resonance effect than partial noise. PMID:23848761

  15. Stochastic resonance, reverse-resonance and stochastic multi-resonance in an underdamped quartic double-well potential with noise and delay

    NASA Astrophysics Data System (ADS)

    Du, Lu-Chun; Mei, Dong-Cheng

    2011-10-01

    The stochastic resonance in an underdamped quartic double-well potential with time delayed feedback is studied numerically. The signal power amplification is employed to characterize the stochastic resonance of the system. Simulation results indicate that: (i) for moderate frequency of the periodic driving, the stochastic resonance is decreased monotonically by increasing the delay time, but at high frequency, the reverse-resonance is induced to transform into a stochastic resonance by time delay; (ii) the damping coefficient has a critical value for which the stochastic resonance is optimum; (iii) a stochastic multi-resonance emerges when the signal power amplification is a function of the driving frequency.

  16. Stochastic resonance in an intracellular genetic perceptron.

    PubMed

    Bates, Russell; Blyuss, Oleg; Zaikin, Alexey

    2014-03-01

    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

  17. A new model of geometry-induced stochastic resonance

    NASA Astrophysics Data System (ADS)

    Zheng, Chunming; Guo, Wei; Du, Luchun; Mei, Dongcheng

    2014-03-01

    We propose a new model where entropic stochastic resonance and geometric stochastic resonance can both be observed by controlling the geometry parameters and the external force. Such stochastic resonance manifests a more adjustable character in small-scale systems where confinement and noise play a prominent role. The magnitude of the effect is sensitive to the geometry modification, thus leading to various resonance conditions. The novel phenomenon found could thus be beneficial for the control of the basic properties in these systems.

  18. Reverse resonance and stochastic resonance in intracellular calcium oscillations

    NASA Astrophysics Data System (ADS)

    Duan, Wei-Long; Long, Fei; Li, Chun

    2014-05-01

    The roles of time delay on the coherence resonance are investigated in the intracellular calcium oscillation system described by the processes of active and passive transport of intracellular Ca2+ driven by colored noises. From the numerical simulation of the reciprocal coefficient of variance of interspike intervals of calcium spikes by the method of second-order algorithm, the results indicate that: (i) The stochastic or reverse synchronization is induced by a certain value of time delay or correlation time; (ii) A phenomenon of reverse resonance can be obtained in the function of reciprocal coefficient of variance vs. time delay or vs. strength of noises as time delay increases; (iii) Both stochastic and reverse resonance are observed in the function of reciprocal coefficient of variance vs. correlation time with varying strength of noises.

  19. Stochastic resonance at nonequilibrium phase transitions

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    Thermal pulsations in a transition from a nucleate to a film regime of water boiling on a wire heater with a periodic Joule heat release have been studied experimentally. At frequencies of the periodic action smaller than 0.1 Hz the intermittency of the nucleate and film boiling regimes was observed. In this case the amplitude of thermal pulsations increased. The experiments with an additional noise source were carried out. With an increase in the intensity of the noise the power of the output periodic mode increased and reaching the maximum began to decrease. The results are interpreted as stochastic resonance when the periodic component of pulsations increases in the presence of noise. The results show that in a complex system with nonequilibrium phase transitions there can occur both the extreme fluctuations with 1 / f power spectrum and stochastic resonance under external periodic action.

  20. Enhanced logical stochastic resonance under periodic forcing

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  1. Geometric stochastic resonance in a double cavity

    NASA Astrophysics Data System (ADS)

    Ghosh, Pulak K.; Glavey, Russell; Marchesoni, Fabio; Savel'Ev, Sergey E.; Nori, Franco

    2011-07-01

    Geometric stochastic resonance of particles diffusing across a porous membrane subject to oscillating forces is characterized as a synchronization process. Noninteracting particle currents through a symmetric membrane pore are driven either perpendicular or parallel to the membrane, whereas, harmonic-mixing spectral current components are generated by the combined action of perpendicular and parallel drives. In view of potential applications to the transport of colloids and biological molecules through narrow pores, we also consider the role of particle repulsion as a controlling factor.

  2. [Stochastic resonance in biosystem and its applications].

    PubMed

    Zhu, Danhua; Chen, Yuquan; Pan, Min

    2009-02-01

    Stochastic resonance (SR) is given to a phenomenon that is manifest in nonlinear systems whereby generally feeble input information can be amplified and optimized by the assistance of noise. First, the basic concepts and the characteristic quantities of SR are introduced in this paper. Second, SR in biological system and its applications are reviewed in detail. At last, a summary is presented and the future researches on SR are prospected. PMID:19334584

  3. Improved sensorimotor performance via stochastic resonance.

    PubMed

    Mendez-Balbuena, Ignacio; Manjarrez, Elias; Schulte-Mönting, Jürgen; Huethe, Frank; Tapia, Jesus A; Hepp-Reymond, Marie-Claude; Kristeva, Rumyana

    2012-09-01

    Several studies about noise-enhanced balance control in humans support the hypothesis that stochastic resonance can enhance the detection and transmission in sensorimotor system during a motor task. The purpose of the present study was to extend these findings in a simpler and controlled task. We explored whether a particular level of a mechanical Gaussian noise (0-15 Hz) applied on the index finger can improve the performance during compensation for a static force generated by a manipulandum. The finger position was displayed on a monitor as a small white point in the center of a gray circle. We considered a good performance when the subjects exhibited a low deviation from the center of this circle and when the performance had less variation over time. Several levels of mechanical noise were applied on the manipulandum. We compared the performance between zero noise (ZN), optimal noise (ON), and high noise (HN). In all subjects (8 of 8) the data disclosed an inverted U-like graph between the inverse of the mean variation in position and the input noise level. In other words, the mean variation was significantly smaller during ON than during ZN or HN. The findings suggest that the application of a tactile-proprioceptive noise can improve the stability in sensorimotor performance via stochastic resonance. Possible explanations for this improvement in motor precision are an increase of the peripheral receptors sensitivity and of the internal stochastic resonance, causing a better sensorimotor integration and an increase in corticomuscular synchronization. PMID:22956850

  4. Active and reactive power in stochastic resonance for energy harvesting

    E-print Network

    Kubota, Madoka; Hikihara, Takashi

    2015-01-01

    A power allocation to active and reactive power in stochastic resonance is discussed for energy harvesting from mechanical noise. It is confirmed that active power can be increased at stochastic resonance, in the same way of the relationship between energy and phase at an appropriate setting in resonance.

  5. Frequency (Stochastic) Resonance and Stochastic Resonance for a Superconducting Junctions' Device

    NASA Astrophysics Data System (ADS)

    Li, Jing-Hui

    2014-06-01

    In this paper, we investigate a Josephson-junction device with dichotomous resistance or a special SQUID (superconducting quantum interference device). It is shown that frequency (stochastic) resonance and stochastic resonance can appear for some suitably selected parameters' values of the device respectively. Our results can provide some insights for the investigation of the SQUID response to the signal (including the input alternating current, the added alternating voltage, the vertically added alternating magnetic field, and the detected (electric-magnetic) temporal-periodic signal).

  6. Stochastic resonance in passive and active electronic circuits

    SciTech Connect

    Anishchenko, V.S.; Khovanov, I.A.; Shulgin, B.V. [Laboratory of Nonlinear Dynamics, Saratov State University, Saratov (Russia)

    1996-06-01

    The phenomenon of stochastic resonance in a bistable system modeling overdamped oscillator is studied by numerical simulations and experiments. Experimental data are compared with theoretical results. Stochastic resonance in Chua{close_quote}s circuit is investigated in detail for different regimes of its own dynamics. The main characteristics of stochastic resonance for different regimes under the adiabatic approximation are compared. {copyright} {ital 1996 American Institute of Physics.}

  7. [Research progress of stochastic resonance in neural models].

    PubMed

    Liang, Xiaobing; Liu, Xishun; Liu, Anzhi; Wang, Boliang

    2009-08-01

    In nonlinear systems, noise can improve the responses of the systems with appropriate noise intensity. This phenomenon is called stochastic resonance. Biological neural systems are noisy and stochastic resonance has been found in them experimentally and theoretically. Now many researches focus on the signal transmission and processing in neural models. So this paper introduces the researches of stochastic resonance in noisy neural models. Then the recent research achievement and progress are reviewed in the following three aspects: noise; the development of stochastic resonance; and neural network. At last, the foreground of the study is discussed. PMID:19813639

  8. Noise-free logical stochastic resonance.

    PubMed

    Gupta, Animesh; Sohane, Aman; Kohar, Vivek; Murali, K; Sinha, Sudeshna

    2011-11-01

    The phenomena of logical stochastic resonance (LSR) was demonstrated recently [Phys. Rev. Lett. 102, 104101 (2009)]: namely, when a bistable system is driven by two inputs it consistently yields a response mirroring a logic function of the two inputs in an optimal window of moderate noise. Here we examine the intriguing possibility of obtaining dynamical behavior equivalent to LSR in a noise-free bistable system, subjected only to periodic forcing, such as sinusoidal driving or rectangular pulse trains. We find that such a system, despite having no stochastic influence, also yields phenomena analogous to LSR, in an appropriate window of frequency and amplitude of the periodic forcing. The results are corroborated by circuit experiments. PMID:22181464

  9. Stochastic resonance and 1/f noise at coupled phase transitions

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    The system of two nonlinear stochastic equations simulating 1/f fluctuations during the interaction of nonequilibrium phase transitions in the presence of an external periodic action has been studied by numerical methods. It is shown that in the system there appears stochastic resonance, which leads to an amplification of the output periodic signal under the action of noise. To a random process with a 1/f power spectrum corresponds the maximum Gibbs-Shannon informational entropy. At stochastic resonance the informational entropy is minimum. A new behavior of a two-dimensional system at stochastic resonance has been revealed: at low frequencies of a periodic action with an increased white noise intensity the system trajectories are limited by two mutually perpendicular directions-anisotropic stochastic resonance. With a further increase in the white noise intensity in the system one can observe “ordinary” stochastic resonance, when the increasing intensity of fluctuations in the vicinity of the driving frequency is smeared in the directions.

  10. Stochastic resonance in mammalian neuronal networks

    SciTech Connect

    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

    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.}

  11. The unsaturated bistable stochastic resonance system.

    PubMed

    Zhao, Wenli; Wang, Juan; Wang, Linze

    2013-09-01

    We investigated the characteristics of the output saturation of the classical continuous bistable system (saturation bistable system) and its impact on stochastic resonance (SR). We further proposed a piecewise bistable SR system (unsaturated bistable system) and developed the expression of signal-to-noise ratio (SNR) using the adiabatic approximation theory. Compared with the saturation bistable system, the SNR is significantly improved in our unsaturated bistable SR system. The numerical simulation showed that the unsaturated bistable system performed better in extracting weak signals from strong background noise than the saturation bistable system. PMID:24089953

  12. Fractional Brownian motors and stochastic resonance.

    PubMed

    Goychuk, Igor; Kharchenko, Vasyl

    2012-05-01

    We study fluctuating tilt Brownian ratchets based on fractional subdiffusion in sticky viscoelastic media characterized by a power law memory kernel. Unlike the normal diffusion case, the rectification effect vanishes in the adiabatically slow modulation limit and optimizes in a driving frequency range. It is shown also that the anomalous rectification effect is maximal (stochastic resonance effect) at optimal temperature and can be of surprisingly good quality. Moreover, subdiffusive current can flow in the counterintuitive direction upon a change of temperature or driving frequency. The dependence of anomalous transport on load exhibits a remarkably simple universality. PMID:23004727

  13. Improving watermark detection performance using suprathreshold stochastic resonance

    Microsoft Academic Search

    Rajib Kumar Jha; P. K. Biswas; D. Mishra

    2010-01-01

    Digital watermarking is an important tool to protect digital data. In this paper a novel method is introduced which improves the watermark detection performance using suprathreshold stochastic resonance. The detection performance is computed using correlation as a parameter. We found that the correlation between original watermark and the stochastic resonance based discrete wavelet transform coefficients of the watermarked image improves.

  14. Stochastic resonance with a mesoscopic reaction-diffusion system.

    PubMed

    Mahara, Hitoshi; Yamaguchi, Tomohiko; Parmananda, P

    2014-06-01

    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

  15. Stochastic resonance with a mesoscopic reaction-diffusion system

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  16. Isolated central vestibular syndrome.

    PubMed

    Kim, Sung-Hee; Park, Seong-Ho; Kim, Hyo-Jung; Kim, Ji-Soo

    2015-04-01

    Isolated vestibular syndrome may occur all along the vestibular pathways from the peripheral labyrinth to the brain. By virtue of recent developments in clinical neurotology and neuroimaging, however, diagnosis of isolated central vestibulopathy is increasing. Here, we review five distinct syndromes of isolated central vestibular syndrome from lesions restricted to the vestibular nuclei, the nucleus prepositus hypoglossi, the flocculus, the tonsil, and the nodulus, and introduce a new vestibular syndrome from isolated involvement of the inferior cerebellar peduncle. Decreased responses to head impulses do not exclude a central lesion as a cause of isolated vestibular syndrome. Brain imaging, including diffusion-weighted magnetic resonance imaging (MRI), may be falsely negative during the acute phase in patients with isolated vestibular syndrome because of a stroke. Central signs should be sought carefully in patients with isolated vertigo, even when the patients show the features of peripheral vestibulopathy and negative MRIs. Recognition of these isolated central vestibular syndromes would aid in defining the lesions responsible for various vestibular manifestations in central vestibulopathy. PMID:25735822

  17. Stochastic resonance between propagating extended attractors

    SciTech Connect

    Dell'Erba, M. G.; Izus, G. G.; Deza, R. R. [IFIMAR (UNMdP and CONICET), Dean Funes 3350, B7602AYL Mar del Plata (Argentina); Wio, H. S. [IFCA (UC and CSIC), Avda. de los Castros, s/n, E-39005 Santander (Spain)

    2011-03-24

    The nonequilibrium Ising--Bloch (NIB) bifurcation of the FitzHugh-Nagumo (FHN) model with nondiffusing inhibitor provides a beautiful instance of an extended bistable system with counterpropagating fronts or Bloch walls (BW) as stable attractors. Moreover, these fronts are chiral and parity-related, and the barrier between them is the unstable stationary front or Ising wall (IW). Here we show by means of numerical simulation the presence of stochastic resonance in the transition between 1D BW of opposite chiralities when an additive noise is included. A scaling law of the signal-to-noise ratio (SNR) with the distance to the critical point is numerically observed and theoretically characterized in terms of an effective nonequilibrium potential.

  18. Stochastic resonance between propagating extended attractors

    NASA Astrophysics Data System (ADS)

    dell'Erba, M. G.; Izús, G. G.; Deza, R. R.; Wio, H. S.

    2011-03-01

    The nonequilibrium Ising—Bloch (NIB) bifurcation of the FitzHugh—Nagumo (FHN) model with nondiffusing inhibitor provides a beautiful instance of an extended bistable system with counterpropagating fronts or Bloch walls (BW) as stable attractors. Moreover, these fronts are chiral and parity-related, and the barrier between them is the unstable stationary front or Ising wall (IW). Here we show by means of numerical simulation the presence of stochastic resonance in the transition between 1D BW of opposite chiralities when an additive noise is included. A scaling law of the signal-to-noise ratio (SNR) with the distance to the critical point is numerically observed and theoretically characterized in terms of an effective nonequilibrium potential.

  19. Deterministic stochastic resonance in a Rössler oscillator

    NASA Astrophysics Data System (ADS)

    Arai, Kenichi; Mizutani, Shin; Yoshimura, Kazuyuki

    2004-02-01

    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.

  20. Deterministic stochastic resonance in a Rössler oscillator.

    PubMed

    Arai, Kenichi; Mizutani, Shin; Yoshimura, Kazuyuki

    2004-02-01

    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

  1. Stochastic Resonance Crossovers in Complex Networks

    PubMed Central

    Pinamonti, Giovanni; Marro, J.; Torres, Joaquín J.

    2012-01-01

    Here we numerically study the emergence of stochastic resonance as a mild phenomenon and how this transforms into an amazing enhancement of the signal-to-noise ratio at several levels of a disturbing ambient noise. The setting is a cooperative, interacting complex system modelled as an Ising-Hopfield network in which the intensity of mutual interactions or “synapses” varies with time in such a way that it accounts for, e.g., a kind of fatigue reported to occur in the cortex. This induces nonequilibrium phase transitions whose rising comes associated to various mechanisms producing two types of resonance. The model thus clarifies the details of the signal transmission and the causes of correlation among noise and signal. We also describe short-time persistent memory states, and conclude on the limited relevance of the network wiring topology. Our results, in qualitative agreement with the observation of excellent transmission of weak signals in the brain when competing with both intrinsic and external noise, are expected to be of wide validity and may have technological application. We also present here a first contact between the model behavior and psychotechnical data. PMID:23272090

  2. Stochastic resonance crossovers in complex networks.

    PubMed

    Pinamonti, Giovanni; Marro, J; Torres, Joaquín J

    2012-01-01

    Here we numerically study the emergence of stochastic resonance as a mild phenomenon and how this transforms into an amazing enhancement of the signal-to-noise ratio at several levels of a disturbing ambient noise. The setting is a cooperative, interacting complex system modelled as an Ising-Hopfield network in which the intensity of mutual interactions or "synapses" varies with time in such a way that it accounts for, e.g., a kind of fatigue reported to occur in the cortex. This induces nonequilibrium phase transitions whose rising comes associated to various mechanisms producing two types of resonance. The model thus clarifies the details of the signal transmission and the causes of correlation among noise and signal. We also describe short-time persistent memory states, and conclude on the limited relevance of the network wiring topology. Our results, in qualitative agreement with the observation of excellent transmission of weak signals in the brain when competing with both intrinsic and external noise, are expected to be of wide validity and may have technological application. We also present here a first contact between the model behavior and psychotechnical data. PMID:23272090

  3. Enhancement and weakening of stochastic resonance for a coupled system.

    PubMed

    Li, Jing-hui

    2011-12-01

    In the paper, we investigate the phenomenon of stochastic resonance of a system with finite locally coupled linear elements driven by multiplicative dichotomous noise and temporal periodic signal. It is shown that, for some suitably selected values of the parameters, with increasing the size of the system or the coupling among the nearest elements, the stochastic resonance phenomenon can be enhanced; while for some other suitably selected parameters' values, with the increase of the size or the coupling, the phenomenon of stochastic resonance can be weakened. Our results can provide some useful insights for the investigation of the stochastic resonance phenomenon of the systems with locally (or globally) coupled finite (or infinite) elements. PMID:22225352

  4. Stochastic resonance: non-robust and robust tuning notions

    E-print Network

    A30, 37N10 Keywords: Stochastic resonance, spectral gap, stochastic differential equation, energy periodicity with a measure of quality of tuning. Notions of quality of tuning widely used in physics such as the spectral power amplification or the signal-to-noise ratio depend on the spectral properties of the averaged

  5. A microprocessor-based multichannel subsensory stochastic resonance electrical stimulator.

    PubMed

    Chang, Gwo-Ching

    2013-01-01

    Stochastic resonance electrical stimulation is a novel intervention which provides potential benefits for improving postural control ability in the elderly, those with diabetic neuropathy, and stroke patients. In this paper, a microprocessor-based subsensory white noise electrical stimulator for the applications of stochastic resonance stimulation is developed. The proposed stimulator provides four independent programmable stimulation channels with constant-current output, possesses linear voltage-to-current relationship, and has two types of stimulation modes, pulse amplitude and width modulation. PMID:24110498

  6. Use of behavioural stochastic resonance by paddle fish for feeding.

    PubMed

    Russell, D F; Wilkens, L A; Moss, F

    1999-11-18

    Stochastic resonance is the phenomenon whereby the addition of an optimal level of noise to a weak information-carrying input to certain nonlinear systems can enhance the information content at their outputs. Computer analysis of spike trains has been needed to reveal stochastic resonance in the responses of sensory receptors except for one study on human psychophysics. But is an animal aware of, and can it make use of, the enhanced sensory information from stochastic resonance? Here, we show that stochastic resonance enhances the normal feeding behaviour of paddlefish (Polyodon spathula), which use passive electroreceptors to detect electrical signals from planktonic prey. We demonstrate significant broadening of the spatial range for the detection of plankton when a noisy electric field of optimal amplitude is applied in the water. We also show that swarms of Daphnia plankton are a natural source of electrical noise. Our demonstration of stochastic resonance at the level of a vital animal behaviour, feeding, which has probably evolved for functional success, provides evidence that stochastic resonance in sensory nervous systems is an evolutionary adaptation. PMID:10580499

  7. Use of behavioural stochastic resonance by paddle fish for feeding

    NASA Astrophysics Data System (ADS)

    Russell, David F.; Wilkens, Lon A.; Moss, Frank

    1999-11-01

    Stochastic resonance is the phenomenon whereby the addition of an optimal level of noise to a weak information-carrying input to certain nonlinear systems can enhance the information content at their outputs. Computer analysis of spike trains has been needed to reveal stochastic resonance in the responses of sensory receptors except for one study on human psychophysics. But is an animal aware of, and can it make use of, the enhanced sensory information from stochastic resonance? Here, we show that stochastic resonance enhances the normal feeding behaviour of paddlefish (Polyodon spathula), which use passive electroreceptors to detect electrical signals from planktonic prey. We demonstrate significant broadening of the spatial range for the detection of plankton when a noisy electric field of optimal amplitude is applied in the water. We also show that swarms of Daphnia plankton are a natural source of electrical noise. Our demonstration of stochastic resonance at the level of a vital animal behaviour, feeding, which has probably evolved for functional success, provides evidence that stochastic resonance in sensory nervous systems is an evolutionary adaptation.

  8. Stochastic resonance in psychophysics and in animal behavior.

    PubMed

    Ward, Lawrence M; Neiman, Alexander; Moss, Frank

    2002-08-01

    A recent analysis of the energy detector model in sensory psychophysics concluded that stochastic resonance does not occur 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 (2000) Biol Cybern 83: 471-480]. When generalized to signal detection in sensory systems in general, this conclusion is a serious challenge to the idea that stochastic resonance could play a significant role in sensory processing in humans and other animals. It also seems to be inconsistent with recent demonstrations of stochastic resonance in sensory systems of both nonhuman animals and humans using measures of system performance such as signal-to-noise ratio of power spectral densities and percent-correct detections in a two-interval forced-choice paradigm, both closely related to d'. In this paper we address this apparent dilemma by discussing several models of how stochastic resonance can arise in signal detection systems, including especially those that implement a "soft threshold" at the input transform stage. One example involves redefining d' for energy increments in terms of parameters of the spike-count distribution of FitzHugh-Nagumo neurons. Another involves a Poisson spike generator that receives an exponentially transformed noisy periodic signal. In this case it can be shown that the signal-to-noise ratio of the power spectral density at the signal frequency, which exhibits stochastic resonance, is proportional to d'. Finally, a variant of d' is shown to exhibit stochastic resonance when calculated directly from the distributions of power spectral densities at the signal frequency resulting from transformation of noise alone and a noisy signal by a sufficiently steep nonlinear response function. All of these examples, and others from the literature, imply that stochastic resonance is more than an epiphenomenon, although significant limitations to the extent to which adding noise can aid detection do exist. PMID:12181585

  9. Non-Gaussian, non-dynamical stochastic resonance

    NASA Astrophysics Data System (ADS)

    Szczepaniec, Krzysztof; Dybiec, Bart?omiej

    2013-11-01

    The classical model revealing stochastic resonance is a motion of an overdamped particle in a double-well fourth order potential when combined action of noise and external periodic driving results in amplifying of weak signals. Resonance behavior can also be observed in non-dynamical systems. The simplest example is a threshold triggered device. It consists of a periodic modulated input and noise. Every time an output crosses the threshold the signal is recorded. Such a digitally filtered signal is sensitive to the noise intensity. There exists the optimal value of the noise intensity resulting in the "most" periodic output. Here, we explore properties of the non-dynamical stochastic resonance in non-equilibrium situations, i.e. when the Gaussian noise is replaced by an ?-stable noise. We demonstrate that non-equilibrium ?-stable noises, depending on noise parameters, can either weaken or enhance the non-dynamical stochastic resonance.

  10. Reverse stochastic resonance in a hippocampal CA1 neuron model.

    PubMed

    Durand, Dominique M; Kawaguchi, Minato; Mino, Hiroyuki

    2013-01-01

    Stochastic resonance (SR) is a ubiquitous and counter- intuitive phenomenon whereby the addition of noise to a non-linear system can improve the detection of sub-threshold signals. The "signal" is normally periodic or deterministic whereas the "noise" is normally stochastic. However, in neural systems, signals are often stochastic. Moreover, periodic signals are applied near neurons to control neural excitability (i.e. deep brain stimulation). We therefore tested the hypothesis that a quasi-periodic signal applied to a neural network could enhance the detection of a stochastic neural signal (reverse stochastic resonance). Using computational methods, a CA1 hippocampal neuron was simulated and a Poisson distributed subthreshold synaptic input ("signal") was applied to the synaptic terminals. A periodic or quasi periodic pulse train at various frequencies ("noise") was applied to an extracellular electrode located near the neuron. The mutual information and information transfer rate between the output and input of the neuron were calculated. The results display the signature of stochastic resonance with information transfer reaching a maximum value for increasing power (or frequency) of the "noise". This result shows that periodic signals applied extracellularly can improve the detection of subthreshold stochastic neural signals. The optimum frequency (110 Hz) is similar to that used in patients with Parkinson's suggesting that this phenomenon could play a role in the therapeutic effect of high frequency stimulation. PMID:24110918

  11. Stimulus profile and modeling of continuous galvanic vestibular stimulation in functional magnetic resonance imaging.

    PubMed

    Stephan, Thomas; Hüfner, Katharina; Brandt, Thomas

    2009-05-01

    Both direct current (DC) and alternating current (AC) have been used for galvanic vestibular stimulation (GVS) during functional MRI (fMRI). The perceptual effects of apparent rotation persist while the current is being applied, but there is a subjective decay over the entire stimulation period. Particularly during DC-GVS in a supine position, subjects report a strong vestibular sensation related to the onset and offset of the stimulus, and weaker effects during constant DC-GVS stimulation. In the present study, we analyzed DC-GVS fMRI data from a group of volunteers with two different statistical models. In model I, the effects of GVS were modeled as a single regressor that described the periods during which the current was switched on. In model II, an additional regressor describing the onset and offset of the stimulation was included. The activation pattern found by using model I included only a subset of the activation patterns known to respond to vestibular stimulation from previous imaging studies. Model II revealed two different activation maps: block effects similar to the results obtained in model I and additional transient GVS effects with larger activation clusters and higher t-values. This extended activation pattern resembled the results obtained during AC-GVS, including multisensory vestibular projection areas. We show that the major part of the blood oxygenation level dependent (BOLD) responses elicited by DC-GVS is related to the on- and offset of stimulation currents and reflects the perceptual experience just-described. In addition, the separate modeling of transient and persistent effects of DC-GVS can identify distinct cortical correlates of those effects. PMID:19645951

  12. Coherent signal amplification in bistable nanomechanical oscillators by stochastic resonance.

    PubMed

    Badzey, Robert L; Mohanty, Pritiraj

    2005-10-13

    Stochastic resonance is a counterintuitive concept: the addition of noise to a noisy system induces coherent amplification of its response. First suggested as a mechanism for the cyclic recurrence of ice ages, stochastic resonance has been seen in a wide variety of macroscopic physical systems: bistable ring lasers, superconducting quantum interference devices (SQUIDs), magnetoelastic ribbons and neurophysiological systems such as the receptors in crickets and crayfish. Although fundamentally important as a mechanism of coherent signal amplification, stochastic resonance has yet to be observed in nanoscale systems. Here we report the observation of stochastic resonance in bistable nanomechanical silicon oscillators. Our nanomechanical systems consist of beams that are clamped at each end and driven into transverse oscillation with the use of a radiofrequency source. Modulation of the source induces controllable switching of the beams between two stable, distinct states. We observe that the addition of white noise causes a marked amplification of the signal strength. Stochastic resonance in nanomechanical systems could have a function in the realization of controllable high-speed nanomechanical memory cells, and paves the way for exploring macroscopic quantum coherence and tunnelling. PMID:16222295

  13. Stochastic resonance and coherence resonance in groundwater-dependent plant ecosystems.

    PubMed

    Borgogno, Fabio; D'Odorico, Paolo; Laio, Francesco; Ridolfi, Luca

    2012-01-21

    Several studies have shown that non-linear deterministic dynamical systems forced by external random components can give rise to unexpectedly regular temporal behaviors. Stochastic resonance and coherence resonance, the two best known processes of this type, have been studied in a number of physical and chemical systems. Here, we explore their possible occurrence in the dynamics of groundwater-dependent plant ecosystems. To this end, we develop two eco-hydrological models, which allow us to demonstrate that stochastic and coherence resonance may emerge in the dynamics of phreatophyte vegetation, depending on their deterministic properties and the intensity of external stochastic drivers. PMID:21968441

  14. Tracking stochastic resonance curves using an assisted reference model

    NASA Astrophysics Data System (ADS)

    Calderón Ramírez, Mario; Rico Martínez, Ramiro; Ramírez Álvarez, Elizeth; Parmananda, P.

    2015-06-01

    The optimal noise amplitude for Stochastic Resonance (SR) is located employing an Artificial Neural Network (ANN) reference model with a nonlinear predictive capability. A modified Kalman Filter (KF) was coupled to this reference model in order to compensate for semi-quantitative forecast errors. Three manifestations of stochastic resonance, namely, Periodic Stochastic Resonance (PSR), Aperiodic Stochastic Resonance (ASR), and finally Coherence Resonance (CR) were considered. Using noise amplitude as the control parameter, for the case of PSR and ASR, the cross-correlation curve between the sub-threshold input signal and the system response is tracked. However, using the same parameter the Normalized Variance curve is tracked for the case of CR. The goal of the present work is to track these curves and converge to their respective extremal points. The ANN reference model strategy captures and subsequently predicts the nonlinear features of the model system while the KF compensates for the perturbations inherent to the superimposed noise. This technique, implemented in the FitzHugh-Nagumo model, enabled us to track the resonance curves and eventually locate their optimal (extremal) values. This would yield the optimal value of noise for the three manifestations of the SR phenomena.

  15. Spatial stochastic resonance in one-dimensional Ising systems.

    PubMed

    Néda, Z; Rusz, A; Ravasz, E; Lakdawala, P; Gade, P M

    1999-10-01

    The one-dimensional Ising model is analytically studied in a spatially periodic and oscillatory external magnetic field using the transfer-matrix method. For low enough magnetic field intensities the correlation between the external magnetic field and the response in magnetization presents a maximum for a given temperature. The phenomenon can be interpreted as a resonance phenomenon induced by the stochastic heat bath. This "spatial stochastic resonance" is realized in the equilibrium state and not as a dynamical response to the external time-periodic driving. PMID:11970258

  16. Interplay between Detection Strategies and Stochastic Resonance Properties

    E-print Network

    Addesso, Paolo; Filatrella, Giovanni

    2015-01-01

    We discuss how to exploit stochastic resonance with the methods of statistical theory of decisions. To do so, we evaluate two detection strategies: escape time analysis and strobing. For a standard quartic bistable system with a periodic drive and disturbed by noise, we show that the detection strategies and the physics of the double well are connected, inasmuch as one (the strobing strategy) is based on synchronization, while the other (escape time analysis) is determined by the possibility to accumulate energy in the oscillations. The analysis of the escape times best performs at the frequency of the geometric resonance, while strobing shows a peak of the performances at a special noise level predicted by the stochastic resonance theory. We surmise that the detection properties of the quartic potential are generic for overdamped and underdamped systems, in that the physical nature of resonance decides the competition (in terms of performances) between different detection strategies.

  17. Stochastic resonance for motion of flexible macromolecules in solution.

    PubMed

    Dikshtein, Igor E; Kuznetsov, Dmitri V; Schimansky-Geier, Lutz

    2002-06-01

    We consider a dilute or semidilute polymer solution with localized attracting centers near a flat phase boundary and assume it driven by both stochastic and periodic forces. The attracting inhomogeneities restrict the free motion of macromolecules and play the role of fixed pinning centers. The flat boundary is modeled by a bistable potential whose minima attract the movable polymer segments between neighboring pinning points. We study the motion of these segments. The stochastic forces lead to stochastic oscillations of the polymer parts between the two potential wells near the phase boundary. Application of a small temporal periodic force can synchronize these oscillations and leads to the phenomenon of stochastic resonance for a nonvanishing noise intensity. As an outcome of our theory in agreement with numerical simulations, the resonance is stronger for wider and/or less deep potentials and observed at smaller values of the noise intensity. Additionally, we discuss under what conditions doubly stochastic resonance of the macromolecular motion occurs, that is, if bistability of the potential near the boundary originates in the action of multiplicative noise. PMID:12188697

  18. Stochastic resonance as an emergent property of neural networks

    NASA Astrophysics Data System (ADS)

    Lopes, M. A.; Goltsev, A. V.; Lee, K.-E.; Mendes, J. F. F.

    2013-01-01

    In biological sensory systems, a presence of noise can actually enhance detection of weak signals. This phenomenon is called stochastic resonance (SR). We show that SR can emerge as a collective phenomenon in neural networks. We consider a cortical circuit model composed by stochastic excitatory and inhibitory neurons that form a sparsely connected network. We find that SR appears due to nonlinear dynamics in a region near the critical point of a dynamical phase transition to network oscillations. The critical point is actually an emergent threshold in the collective dynamics. Using the cortical model, we mimic experiments of Gluckman et al. [B. J. Gluckman et al., PRL 77, 4098 (1996)] that observed stochastic resonance in a response of CA1 networks from mammalian brain on periodic electric stimuli. Results of our numerical calculations are in agreement both qualitatively and quantitatively with these experiments.

  19. Statistical analysis of stochastic resonance in a thresholded detector

    E-print Network

    Wefelmeyer, Wolfgang

    Statistical analysis of stochastic resonance in a thresholded detector Priscilla E. Greenwood be detected if noise is added to the data. The noisy signal must be strong enough to exceed the threshold at least occasionally; but very strong noise tends to drown out the signal. There is an optimal noise level

  20. Stochastic resonance in a model neuron with reset

    Microsoft Academic Search

    Hans E. Plesser; Shigeru Tanaka

    1997-01-01

    The response of a noisy integrate-and-fire neuron with reset to periodic input is investigated. We numerically obtain the first-passage-time density of the pertaining Ornstein-Uhlenbeck process and show how the power spectral density of the resulting spike train can be determined via Fourier transform. The neuron's output clearly exhibits stochastic resonance.

  1. Stochastic resonance in a double quantum dot system

    NASA Astrophysics Data System (ADS)

    Joshi, Amitabh

    2008-02-01

    Stochastic resonance (SR) is theoretically investigated for a double quantum dot system represented by two discrete levels in respective wells. The system is driven by a periodic signal and a white noise source with variable amplitude, and thus displays an improved output signal-to-noise ratio, a characteristic signature of SR.

  2. Enhanced coding for exponentially distributed signals using suprathreshold stochastic resonance

    NASA Astrophysics Data System (ADS)

    Das, Aruneema; Stocks, Nigel G.; Hines, Evor L.

    2009-01-01

    Our previous work on stochastic resonance (SR) in threshold based systems proved that the SR effect is dependent on the nature of the input signal distribution; more specifically, for certain types of signal distribution SR is not observed [Das A, Stocks NG, Nikitin A, Hines EL. Quantifying stochastic resonance in a single threshold detector for random aperiodic signals. Fluctuation Noise Lett 2004;4:L247-65]. Here we show that suprathreshold stochastic resonance (SSR) - a novel and distinct form of SR - removes this limitation and hence leads to the conclusion that SSR can probably enhance the transmission of signals of any distribution and amplitude. SSR effects are studied in a parallel array of identical nonlinear threshold based devices. A double exponential signal distribution is chosen because this distribution did not demonstrate conventional SR effects in a single threshold device [Das A, Stocks NG, Nikitin A., Hines EL. Quantifying Stochastic resonance in a single threshold detector for random aperiodic signals. Fluctuation and Noise Letters 2004;4:L247-L265.]. SSR as a possible mechanism for enhancing transmission of speech signals in the human ear is also discussed.

  3. Observation of stochastic resonance in a ring laser

    Microsoft Academic Search

    Bruce McNamara; Kurt Wiesenfeld; Rajarshi Roy

    1988-01-01

    The first observation of stochastic resonance in an optical device, the bidirectional ring laser, is reported. The experiment exploits a new technique to modulate periodically the asymmetry between the two counter-rotating lasing modes. The measurements verify that the addition of injected noise can lead to an improved signal-to-noise ratio (relative to that observed with no externally injected noise).

  4. NONLINEAR ESTIMATION FROM QUANTIZED SIGNALS: QUANTIZER OPTIMIZATION AND STOCHASTIC RESONANCE.

    E-print Network

    Chapeau-Blondeau, François

    with noises belonging to the famility of generalized Gaussians, which occur in particular in ocean acoustics representation by a two-level quantizer of the signal-plus-noise mixture. By considering the Fisher information]. In a typical instance of stochastic resonance, a signal­noise mixture interacts with a nonlinear system

  5. Stochastic resonance in the Weidlich model of public opinion formation

    NASA Astrophysics Data System (ADS)

    Babinec, Peter

    1997-02-01

    As a prototypical nonlinear sociological system we study the Weidlich model of public opinion formation. At an optimal value of the collective climate parameter (which plays the role of noise for this system) we have found a maximal value of signal-to-noise ratio and a largest amplification of a periodic external preference factor which are the characteristics of stochastic resonance.

  6. Signal detection theory, detectability and stochastic resonance effects.

    PubMed

    Tougaard, Jakob

    2002-08-01

    Stochastic resonance is a phenomenon in which the performance of certain non-linear detectors can be enhanced by the addition of appropriate levels of random noise. Signal detection theory offers a powerful tool for analysing this type of system, through an ability to separate detection processes into reception and classification, with the former generally being linear and the latter always non-linear. Through appropriate measures of signal detectability it is possible to decide whether a local improvement in detection via stochastic resonance occurs due to the non-linear effects of the classification process. In this case, improvement of detection through the addition of noise can never improve detection beyond that of a corresponding adaptive system. Signal detection and stochastic resonance is investigated in several integrate-and-fire neuron models. It is demonstrated that the stochastic resonance observed in spiking models is caused by non-linear properties of the spike-generation process itself. The true detectability of the signal, as seen by the receiver part of the spiking neuron (the integrator part), decreases monotonically with input noise level for all signal and noise intensities. PMID:12181584

  7. Stochastic resonance in a double quantum dot system.

    PubMed

    Joshi, Amitabh

    2008-02-01

    Stochastic resonance (SR) is theoretically investigated for a double quantum dot system represented by two discrete levels in respective wells. The system is driven by a periodic signal and a white noise source with variable amplitude, and thus displays an improved output signal-to-noise ratio, a characteristic signature of SR. PMID:18351970

  8. Aerosolic time series and stochastic resonance

    Microsoft Academic Search

    S. de Martino; M. Falanga; L. Mona

    2003-01-01

    Fifteen years long time series (November 1978-May 1993) of Aerosol Index data provided by the TOMS have been analysed. In the power spectrum of these signals, there is a principal peak characterized by an annual periodicity. Dynamical analysis reveals the high dimensionality of this system and an important stochastic component in the observed signals. The ICA Independent Component Analysis was

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

    PubMed

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

    2014-08-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  11. Reconstruction of pulse noisy images via stochastic resonance

    PubMed Central

    Han, Jing; Liu, Hongjun; Sun, Qibing; Huang, Nan

    2015-01-01

    We investigate a practical technology for reconstructing nanosecond pulse noisy images via stochastic resonance, which is based on the modulation instability. A theoretical model of this method for optical pulse signal is built to effectively recover the pulse image. The nanosecond noise-hidden images grow at the expense of noise during the stochastic resonance process in a photorefractive medium. The properties of output images are mainly determined by the input signal-to-noise intensity ratio, the applied voltage across the medium, and the correlation length of noise background. A high cross-correlation gain is obtained by optimizing these parameters. This provides a potential method for detecting low-level or hidden pulse images in various imaging applications. PMID:26067911

  12. Reconstruction of pulse noisy images via stochastic resonance.

    PubMed

    Han, Jing; Liu, Hongjun; Sun, Qibing; Huang, Nan

    2015-01-01

    We investigate a practical technology for reconstructing nanosecond pulse noisy images via stochastic resonance, which is based on the modulation instability. A theoretical model of this method for optical pulse signal is built to effectively recover the pulse image. The nanosecond noise-hidden images grow at the expense of noise during the stochastic resonance process in a photorefractive medium. The properties of output images are mainly determined by the input signal-to-noise intensity ratio, the applied voltage across the medium, and the correlation length of noise background. A high cross-correlation gain is obtained by optimizing these parameters. This provides a potential method for detecting low-level or hidden pulse images in various imaging applications. PMID:26067911

  13. Stochastic resonance of vortices in a washboard pinning potential

    NASA Astrophysics Data System (ADS)

    Shklovskij, Valerij A.; Dobrovolskiy, Oleksandr V.

    2014-08-01

    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.

  14. Stochastic resonance in hybrid scale-free neuronal networks

    NASA Astrophysics Data System (ADS)

    Yilmaz, Ergin; Uzuntarla, Muhammet; Ozer, Mahmut; Perc, Matjaž

    2013-11-01

    We study the phenomenon of stochastic resonance in a system of coupled neurons that are globally excited by a weak periodic input signal. We make the realistic assumption that the chemical and electrical synapses interact in the same neuronal network, hence constituting a hybrid network. By considering a hybrid coupling scheme embedded in the scale-free topology, we show that the electrical synapses are more efficient than chemical synapses in promoting the best correlation between the weak input signal and the response of the system. We also demonstrate that the average degree of neurons within the hybrid scale-free network significantly influences the optimal amount of noise for the occurrence of stochastic resonance, indicating that there also exists an optimal topology for the amplification of the response to the weak input signal. Lastly, we verify that the presented results are robust to variations of the system size.

  15. Effect of the heterogeneous neuron and information transmission delay on stochastic resonance of neuronal networks.

    PubMed

    Wang, Qingyun; Zhang, Honghui; Chen, Guanrong

    2012-12-01

    We study the effect of heterogeneous neuron and information transmission delay on stochastic resonance of scale-free neuronal networks. For this purpose, we introduce the heterogeneity to the specified neuron with the highest degree. It is shown that in the absence of delay, an intermediate noise level can optimally assist spike firings of collective neurons so as to achieve stochastic resonance on scale-free neuronal networks for small and intermediate ?(h), which plays a heterogeneous role. Maxima of stochastic resonance measure are enhanced as ?(h) increases, which implies that the heterogeneity can improve stochastic resonance. However, as ?(h) is beyond a certain large value, no obvious stochastic resonance can be observed. If the information transmission delay is introduced to neuronal networks, stochastic resonance is dramatically affected. In particular, the tuned information transmission delay can induce multiple stochastic resonance, which can be manifested as well-expressed maximum in the measure for stochastic resonance, appearing every multiple of one half of the subthreshold stimulus period. Furthermore, we can observe that stochastic resonance at odd multiple of one half of the subthreshold stimulus period is subharmonic, as opposed to the case of even multiple of one half of the subthreshold stimulus period. More interestingly, multiple stochastic resonance can also be improved by the suitable heterogeneous neuron. Presented results can provide good insights into the understanding of the heterogeneous neuron and information transmission delay on realistic neuronal networks. PMID:23278058

  16. Stochastic resonance in psychophysics and in animal behavior

    Microsoft Academic Search

    Lawrence M. Ward; Alexander Neiman; Frank Moss

    2002-01-01

    .  ?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

  17. Experimental observation of stochastic resonance in a magnetoelastic ribbon

    Microsoft Academic Search

    M. L. Spano; M. Wun-Fogle; W. L. Ditto

    1992-01-01

    We report the observation of stochastic resonance in a parametrically driven bistable magnetoelastic buckling-ribbon experiment. We have found that the parametric addition of white noise increases the signal-to-noise ratio of the response of the ribbon by 10 to 12 dB relative to that of the ribbon with no externally added noise. We have also observed a characteristic spectrum for the

  18. The Role of Resonances in the Stochastic Limit

    E-print Network

    F. Gomez

    2006-07-17

    In the stochastic limit the resonances play a fundamental role because they determine the generalized susceptivities which are the building blocks of all the physical information which survives in this limit. There are two sources of possible divergences: one related to the singularities of the form factor; another to the chaoticity of the spectrum. The situation will be illustrated starting from the example of the discrete part of the hydrogen atom in interaction with the electromagnetic field.

  19. Thermal enhancement and stochastic resonance of polaron ratchets

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  20. Thermal enhancement and stochastic resonance of polaron ratchets.

    PubMed

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

    2014-06-01

    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

  1. Cyclotron resonance effects on stochastic acceleration of light ionospheric ions

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  2. Stochastic resonance in an over-damped linear oscillator

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  3. Linear and nonlinear experimental regimes of stochastic resonance.

    PubMed

    Mantegna, R N; Spagnolo, B; Trapanese, M

    2001-01-01

    We investigate the stochastic resonance phenomenon in a physical system based on a tunnel diode. The experimental control parameters are set to allow the control of the frequency and amplitude of the deterministic modulating signal over an interval of values spanning several orders of magnitude. We observe both a regime described by the linear-response theory and the nonlinear deviation from it. In the nonlinear regime we detect saturation of the power spectral density of the output signal detected at the frequency of the modulating signal and a dip in the noise level of the same spectral density. When these effects are observed we detect a phase and frequency synchronization between the stochastic output and the deterministic input. PMID:11304228

  4. Stochastic resonance in a periodically modulated dissipative nuclear dynamics

    SciTech Connect

    Berezovoy, V.P. [and others

    2001-02-01

    A fission decay of highly excited periodically driven compound nuclei is considered in the framework of Langevin approach. The authors have used residual-time distribution (RTD) as the tool for studying of dynamic features in a presence of periodic perturbation. The structure of RTD essentially depends on the relation between Kramers decay rate and the frequency {omega} of the periodic perturbation. In particular, intensity of the first peak in RTD has a sharp maximum at certain nuclear temperature depending on {omega}. This maximum should be considered as first-hand manifestation of stochastic resonance in nuclear dynamics.

  5. Stochastic resonance and the trade arrival rate of stocks

    E-print Network

    Silva, A Christian

    2008-01-01

    We studied non-dynamical stochastic resonance for the number of trades in the stock market. The trade arrival rate presents a deterministic pattern that can be modeled by a cosine function perturbed by noise. Due to the nonlinear relationship between the rate and the observed number of trades, the noise can either enhance or suppress the detection of the deterministic pattern. By finding the parameters of our model with intra-day data, we describe the trading environment and illustrate the presence of SR in the trade arrival rate of stocks in the U.S. market.

  6. Phase-shifts in stochastic resonance in a Chua circuit

    E-print Network

    Wojciech Korneta; Iacyel Gomes; Claudio R. Mirasso; Raul Toral

    2007-10-29

    We present an experimental study of stochastic resonance in an electronic Chua circuit operating in the chaotic regime. We study in detail the switch-phase distribution and the phase-shift between sinusoidal forcing for two responses of the circuit: one depending on both inter-well and intra-well dynamics and the other depending only on inter-well dynamics. We describe the two relevant de-synchronizatrion mechanisms for high and low frequencies of the forcing and present a method to detect the optimal noise intensity from switch phases which coincides with the one derived from the observation of the signal-to-noise ratio or residence times.

  7. Stochastic dipolar recoupling in nuclear magnetic resonance of solids

    PubMed Central

    Tycko, Robert

    2008-01-01

    I describe a nuclear magnetic resonance (NMR) technique, called stochastic dipolar recoupling (SDR), that permits continuous experimental control of the character of spin dynamics between coherent and incoherent limits in a system of magnetic dipole-coupled nuclei. In the fully incoherent limit of SDR, spin polarization transfers occur at distance-dependent rates without the quantum mechanical interferences among pairwise dipole-dipole couplings that often limit the feasibility or precision of structural studies of solids by NMR. In addition to facilitating structural studies, SDR represents a possible route to experimental studies of effects of decoherence on the dynamics of quantum many-body systems. PMID:17995438

  8. Dynamical structure underlying inverse stochastic resonance and its implications.

    PubMed

    Uzuntarla, Muhammet; Cressman, John R; Ozer, Mahmut; Barreto, Ernest

    2013-10-01

    We investigate inverse stochastic resonance (ISR), a recently reported phenomenon in which the spiking activity of a Hodgkin-Huxley model neuron subject to external noise exhibits a pronounced minimum as the noise intensity increases. We clarify the mechanism that underlies ISR and show that its most surprising features are a consequence of the dynamical structure of the model. Furthermore, we show that the ISR effect depends strongly on the procedures used to measure it. Our results are important for the experimentalist who seeks to observe the ISR phenomenon. PMID:24229218

  9. Stochastic resonance in multistable systems: the role of dimensionality.

    PubMed

    Nicolis, C

    2012-07-01

    The theory of stochastic resonance in multistable systems is extended to account for both direct transitions between all stable states present and indirect ones involving intermediate states. It is shown that to satisfy these requirements the dynamics needs to be embedded in phase spaces of dimension equal to at least two. Under well defined conditions, the conjunction of the presence of intermediate states and the multidimensional character of the process leads to an enhancement of the response of the system to an external periodic forcing. PMID:23005394

  10. Stochastic Resonance for a SQUID with Dichotomous Resistance

    NASA Astrophysics Data System (ADS)

    Li, Jing-Hui

    2014-03-01

    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).

  11. Stochastic resonance with colored noise for neural signal detection.

    PubMed

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

    2014-01-01

    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

  12. Resonant Phenomenon in a Stochastic Delayed Bistable Chemical System

    NASA Astrophysics Data System (ADS)

    Li, Chunxuan; Yang, Tao

    2015-06-01

    In this paper, the resonant phenomenon for a bistable chemical system in the presence of noises and delayed feedback is investigated. The signal-to-noise ratio (SNR) is calculated when periodic signal is introduced additively (or multiplicatively). The impacts of the parameter ? of the reaction, time delay ?, strength K of the feedback loop, multiplicative ( D) and additive ( Q) noise strengths and cross-correlation strength ? between two noises on the SNR are discussed. When the periodic signal is introduced additively, our results show (i) the SNR as a function of the parameter ? exhibits a maximum, the existence of the maximum is a characteristic of the parametric resonance (PR) phenomenon; (ii) the SNR as a function of D exhibits only a maximum, however, for the case of SNR as a function of Q exhibits not only a maximum, but also a minimum. The existence of the maximum and minimum in the SNR is the identifying characteristics of the stochastic resonance (SR) and reverse-resonance (RR); and (iii) the increases of ?, K and ? enhance the SR and weaken the RR. Finally, we compare the resonant phenomenon for the additive periodic signal with that for multiplicative one in the chemical system.

  13. Stochastic resonance and energy optimization in spatially extended dynamical systems

    NASA Astrophysics Data System (ADS)

    Lai, Y.-C.; Park, K.; Rajagopalan, L.

    2009-05-01

    We investigate a class of nonlinear wave equations subject to periodic forcing and noise, and address the issue of energy optimization. Numerically, we use a pseudo-spectral method to solve the nonlinear stochastic partial differential equation and compute the energy of the system as a function of the driving amplitude in the presence of noise. In the fairly general setting where the system possesses two coexisting states, one with low and another with high energy, noise can induce intermittent switchings between the two states. A striking finding is that, for fixed noise, the system energy can be optimized by the driving in a form of resonance. The phenomenon can be explained by the Langevin dynamics of particle motion in a double-well potential system with symmetry breaking. The finding can have applications to small-size devices such as microelectromechanical resonators and to waves in fluid and plasma.

  14. Stochastic Resonance of Artificial Ion Channels inserted in Small Membrane Patches

    Microsoft Academic Search

    Robert H. Blick; Si-Young Choi; Hyun S. Kim; Sujatha Ramachandran; Daniel W. van der Weide

    2005-01-01

    We investigate stochastic resonance in artificial ion channels inserted in bilipid membranes with varying membrane diameters. Stochastic resonance (SR) is fundamental for sensory reception of organisms, cell systems, single cells and bundles of ion channels. This indicates the importance of SR for applications in systems, such as nano scale single molecular biosensors. For Alamethicin, a standard ion channel model system,

  15. On-chip stochastic resonance of ion channel systems with variable internal noise.

    PubMed

    Stava, Eric; Choi, Siyoung; Kim, Hyun-Seok; Blick, Robert H

    2012-06-01

    We induced stochastic resonance in planar lipid bilayer systems with alamethicin ion channels, and varied alamethicin concentration, membrane area, and applied voltage. We found that membrane-induced microphonic noise significantly affects the signature of stochastic resonance, and that this noise can be used to optimize ion channel-based biosensors. PMID:22411054

  16. Precision constrained stochastic resonance in a feedforward neural network.

    PubMed

    Mtetwa, Nhamoinesu; Smith, Leslie S

    2005-01-01

    Stochastic resonance (SR) is a phenomenon in which the response of a nonlinear system to a subthreshold information-bearing signal is optimized by the presence of noise. By considering a nonlinear system (network of leaky integrate-and-fire (LIF) neurons) that captures the functional dynamics of neuronal firing, we demonstrate that sensory neurons could, in principle harness SR to optimize the detection and transmission of weak stimuli. We have previously characterized this effect by use of signal-to-noise ratio (SNR). Here in addition to SNR, we apply an entropy-based measure (Fisher information) and compare the two measures of quantifying SR. We also discuss the performance of these two SR measures in a full precision floating point model simulated in Java and in a precision limited integer model simulated on a field programmable gate array (FPGA). We report in this study that stochastic resonance which is mainly associated with floating point implementations is possible in both a single LIF neuron and a network of LIF neurons implemented on lower resolution integer based digital hardware. We also report that such a network can improve the SNR and Fisher information of the output over a single LIF neuron. PMID:15732404

  17. Stochastic Resonance Reveals “Pilot Light” Expression in Mammalian Genes

    PubMed Central

    Ptitsyn, Andrey

    2008-01-01

    Background Microarrays are widely used for estimation of expression of thousands of genes in a biological sample. The resolution ability of this method is limited by the background noise. Low expressed genes are detected with insufficient reliability and expression of many genes is never detected at all. Methodology/Principal Findings We have applied the principles of stochastic resonance to detect expression of genes from microarray signals below the background noise level. We report the periodic pattern detected in genes called “Absent” by traditional analysis. The pattern is consistent with expression of the conventionally detected genes and specific to the tissue of origin. This effect is corroborated by the analysis of oscillating gene expression in mouse (M.musculus) and yeast (S. cerevisae). Conclusion/Significance Most genes usually considered silent are in fact expressed at a very low level. Stochastic resonance can be applied to detect changes in expression pattern of low-expressed genes as well as for the validation of the probe performance in microarrays. PMID:18365000

  18. Stochastic resonance in a nonlinear system with a 1/ f spectrum

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    The system of two nonlinear stochastic equations simulating 1/ f fluctuations during the interaction of nonequilibrium phase transitions in the presence of an external harmonic force is analyzed using numerical methods. It is shown that the stochastic resonance occurring in the system enhances the output periodic signal under the action of noise. A random process with a 1/ f power spectrum corresponds to the Gibbs-Shannon information entropy peak. In stochastic resonance, the information entropy is minimal.

  19. An application of stochastic resonance for energy harvesting in a bistable vibrating system

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    The application of stochastic resonance to mechanical energy harvesting is currently of topical interest, and this paper concentrates on an analytical and experimental investigation in which stochastic resonance is deliberately exploited within a bistable mechanical system for optimised energy harvesting. The condition for the occurrence of stochastic resonance is defined conventionally by the Kramers rate, and the modelling of a theoretical nonlinear oscillator driven by a small periodic modulating excitation and a harvestable noise source, which, together satisfy this condition, is developed in the paper. A novel experiment is also discussed which validates this particular form of stochastic resonance, showing that the response can indeed be amplified when the frequency of the weak periodic modulating excitation fulfills the correct occurrence condition. The experimental results indicate that the available power generated under this condition of stochastic resonance is noticeably higher than the power that can be collected under other harvesting conditions.

  20. Balance (or Vestibular) Rehabilitation

    MedlinePLUS

    Balance (or Vestibular) Rehabilitation Audiologic (hearing), balance, and medical diagnostic tests help indicate whether you are a candidate for vestibular (balance) rehabilitation. Vestibular rehabilitation is an individualized balance retraining ...

  1. Comparison of stochastic resonance in static and dynamical nonlinearities

    NASA Astrophysics Data System (ADS)

    Ma, Yumei; Duan, Fabing

    2014-07-01

    We compare the stochastic resonance (SR) effects in parallel arrays of static and dynamical nonlinearities via the measure of output signal-to-noise ratio (SNR). For a received noisy periodic signal, parallel arrays of both static and dynamical nonlinearities can enhance the output SNR by optimizing the internal noise level. The static nonlinearity is easily implementable, while the dynamical nonlinearity has more parameters to be tuned, at the risk of not exploiting the beneficial role of internal noise components. It is of interest to note that, for an input signal buried in the external Laplacian noise, we show that the dynamical nonlinearity is superior to the static nonlinearity in obtaining a better output SNR. This characteristic is assumed to be closely associated with the kurtosis of noise distribution.

  2. Coherence resonance and stochastic tipping points in climate dynamics

    NASA Astrophysics Data System (ADS)

    Pierini, S.

    2011-12-01

    A crucial aspect currently under debate in climate dynamics is whether abrupt climate transitions (such as the glacial terminations and Dansgaard-Oeschger events on the millennial time scale, the Kuroshio Extension bimodal variability on a decadal time scale, etc.) are the result of a tipping point (TP) being exceeded, in which case precursors may be identified, or if they are rather excited by fast noise dynamics. In this context, a case study based on a low-order double-gyre excitable ocean model shows that the TPs of a deterministic, dissipative dynamical system leading to relaxation oscillations (ROs) may have limited physical meaning if the system is perturbed by noise. In this case the transition to ROs occurs via the coherence resonance (CR) mechanism in a parameter range (in which the system is excitable) preceding the deterministic TP. We thus extend the concept of TP so as to incorporate the effect of noise in a single stochastic parameter, the stochastic TP (STP), which identifies abrupt transitions in the corresponding random dynamical system. STPs are shown to anticipate substantially the deterministic TPs in a significant range of noise parameters. The implications concerning the possibility that early warning signals can be detected from climate time series if CR occurs are finally discussed.

  3. Controlled Stochastic Resonance in a Bistable Magnetic System

    NASA Astrophysics Data System (ADS)

    Tutu, H.

    2010-01-01

    A controlled stochastic resonance (SR) with a time-delayed feedback control scheme is studied with a model of bistable magnetic system. The model is given by a stochastic Landau-Lifshitz-Gilbert equation with a sinusoidal field and a time-delayed feedback input field, which regulates SR by feedbacking the delayed state whose delay time equals the half-period of the sinusoidal field. The effect of SR is characterized by power consumption (PC) by the sinusoidal field, which is proportional to the imaginary part of dynamic susceptibility. It is found that the PC exhibits a double-peak structure for two distinctive noise intensities under a certain condition, and that the first peak is relevant to a conventional SR mechanism, but the second is a new one due to the feedback. Around the second peak, one can observe a change in dynamics from a phase-slipping state to a phase-locked state as the noise intensity increases to the second peak point from the minimum point of the PC. T he realization of the phase-locked state, in which the motion of the magnetization vector entrains to the sinusoidal field, reminds us of a ratchetlike mechanism. In this paper, an analytic expression of the dynamic susceptibility is obtained from a dichotomic model, which is deduced from the original Fokker-Planck equation.

  4. A neuron model of stochastic resonance using rectangular pulse trains.

    PubMed

    Danziger, Zachary; Grill, Warren M

    2015-02-01

    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

  5. Temperature-driven coherence resonance and stochastic resonance in a thermochemical system

    NASA Astrophysics Data System (ADS)

    Lemarchand, A.; Gorecki, J.; Gorecki, A.; Nowakowski, B.

    2014-02-01

    We perform the stochastic analysis of a thermochemical system using a master equation which describes a chemical reaction and includes discrete and continuous temperature jumps. We study the time evolution of the system selecting the temperature of the thermostat as an easily tunable control parameter. Depending on the thermostat temperature, the system can be in an excitable, oscillatory, or stationary regime. Stochastic time series for the system temperature are generated and the distributions of interspike intervals are analyzed in the three dynamical regimes separated by a homoclinic bifurcation and a Hopf bifurcation. Different constructive roles of internal fluctuations are exhibited. A noise-induced transition is observed in the vicinity of the Hopf bifurcation. Coherence resonance and stochastic resonance are found in the oscillatory regime. In a range of thermostat temperatures, a nontrivial behavior of the highly nonlinear system is revealed by the existence of both a minimum and a maximum in the scaled standard deviation of interspike intervals as a function of particle number. This high sensitivity to system size illustrates that controlling dynamics in nanoreactors may remain a difficult task.

  6. Temperature-driven coherence resonance and stochastic resonance in a thermochemical system.

    PubMed

    Lemarchand, A; Gorecki, J; Gorecki, A; Nowakowski, B

    2014-02-01

    We perform the stochastic analysis of a thermochemical system using a master equation which describes a chemical reaction and includes discrete and continuous temperature jumps. We study the time evolution of the system selecting the temperature of the thermostat as an easily tunable control parameter. Depending on the thermostat temperature, the system can be in an excitable, oscillatory, or stationary regime. Stochastic time series for the system temperature are generated and the distributions of interspike intervals are analyzed in the three dynamical regimes separated by a homoclinic bifurcation and a Hopf bifurcation. Different constructive roles of internal fluctuations are exhibited. A noise-induced transition is observed in the vicinity of the Hopf bifurcation. Coherence resonance and stochastic resonance are found in the oscillatory regime. In a range of thermostat temperatures, a nontrivial behavior of the highly nonlinear system is revealed by the existence of both a minimum and a maximum in the scaled standard deviation of interspike intervals as a function of particle number. This high sensitivity to system size illustrates that controlling dynamics in nanoreactors may remain a difficult task. PMID:25353554

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  8. Stochastic resonance induced by Lévy noise in a tumor growth model with periodic treatment

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Hao, Mengli; Gu, Xudong; Yang, Guidong

    2014-05-01

    In this paper, the stochastic resonance phenomenon in a tumor growth model under subthreshold periodic therapy and Lévy noise excitation is investigated. The possible reoccurrence of tumor due to stochastic resonance is discussed. The signal-to-noise ratio (SNR) is calculated numerically to measure the stochastic resonance. It is found that smaller stability index is better for avoiding tumor reappearance. Besides, the effect of the skewness parameter on the tumor regrowth is related to the stability index. Furthermore, increasing the intensity of periodic treatment does not always facilitate tumor therapy. These results are beneficial to the optimization of periodic tumor therapy.

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

    PubMed

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

    2014-02-24

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  11. Control of stochastic resonance in bistable systems by using periodic signals

    NASA Astrophysics Data System (ADS)

    Lin, Min; Fang, Li-Min; Zheng, Yong-Jun

    2009-05-01

    According to the characteristic structure of double wells in bistable systems, this paper analyses stochastic fluctuations in the single potential well and probability transitions between the two potential wells and proposes a method of controlling stochastic resonance by using a periodic signal. Results of theoretical analysis and numerical simulation show that the phenomenon of stochastic resonance happens when the time scales of the periodic signal and the noise-induced probability transitions between the two potential wells achieve stochastic synchronization. By adding a bistable system with a controllable periodic signal, fluctuations in the single potential well can be effectively controlled, thus affecting the probability transitions between the two potential wells. In this way, an effective control can be achieved which allows one to either enhance or realize stochastic resonance.

  12. The vestibular system

    NASA Technical Reports Server (NTRS)

    Graybiel, A.

    1973-01-01

    The end organs, central nervous system connections, and static and dynamic characteristics of the vestibular system are presented. Vestibular servation in man and vestibular side effect prevention from space missions involving artificial gravity generation are also considered. Vestibular models and design criteria for rotating space vehicles are appended.

  13. Aperiodic signals processing via parameter-tuning stochastic resonance in a photorefractive ring cavity

    SciTech Connect

    Li, Xuefeng, E-mail: lixfpost@163.com [School of Science, Xi'an University of Post and Telecommunications, Xi'an, 710121 (China)] [School of Science, Xi'an University of Post and Telecommunications, Xi'an, 710121 (China); Cao, Guangzhan; Liu, Hongjun [Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an, 710119 (China)] [Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an, 710119 (China)

    2014-04-15

    Based on solving numerically the generalized nonlinear Langevin equation describing the nonlinear dynamics of stochastic resonance by Fourth-order Runge-Kutta method, an aperiodic stochastic resonance based on an optical bistable system is numerically investigated. The numerical results show that a parameter-tuning stochastic resonance system can be realized by choosing the appropriate optical bistable parameters, which performs well in reconstructing aperiodic signals from a very high level of noise background. The influences of optical bistable parameters on the stochastic resonance effect are numerically analyzed via cross-correlation, and a maximum cross-correlation gain of 8 is obtained by optimizing optical bistable parameters. This provides a prospective method for reconstructing noise-hidden weak signals in all-optical signal processing systems.

  14. Local-feature-based similarity measure for stochastic resonance in visual perception of spatially structured images.

    PubMed

    Delahaies, Agnès; Rousseau, David; Fasquel, Jean-Baptiste; Chapeau-Blondeau, François

    2012-07-01

    For images, stochastic resonance or useful-noise effects have previously been assessed with low-level pixel-based information measures. Such measures are not sensitive to coherent spatial structures usually existing in images. As a result, we show that such measures are not sufficient to properly account for stochastic resonance occurring in visual perception. We introduce higher-level similarity measures, inspired from visual perception, and based on local feature descriptors of scale invariant feature transform (SIFT) type. We demonstrate that such SIFT-based measures allow for an assessment of stochastic resonance that matches the visual perception of images with spatial structures. Constructive action of noise is registered in this way with both additive noise and multiplicative speckle noise. Speckle noise, with its grainy appearance, is particularly prone to introducing spurious spatial structures in images, and the stochastic resonance visually perceived and quantitatively assessed with SIFT-based measures is specially examined in this context. PMID:22751385

  15. NOISE IMPROVEMENT AND STOCHASTIC RESONANCE IN PARALLEL ARRAYS OF SENSORS WITH SATURATION

    E-print Network

    Chapeau-Blondeau, François

    NOISE IMPROVEMENT AND STOCHASTIC RESONANCE IN PARALLEL ARRAYS OF SENSORS WITH SATURATION David ROUSSEAU, Franc¸ois CHAPEAU-BLONDEAU Laboratoire d'Ing´enierie des Syst`emes Automatis´es (LISA), Universit

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

    NASA Astrophysics Data System (ADS)

    Aliev, V. Sh.; Bortnikov, S. G.; Badmaeva, I. A.

    2014-05-01

    The results of stochastic resonance investigation in a nonlinear system, consisting of a microstructure with a polycrystalline vanadium dioxide (VO2) film grown on sapphire and resistor in series are reported. Nonlinearity of the system was provided due to insulator-metal phase transition in VO2. 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 VO2 films grown on silica in our previous investigations. The measured characteristics of microstructures with VO2 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 VO2. For sapphire substrate the output signal-to-noise ratio rose at higher signal frequencies. The stochastic resonance phenomenon in VO2 films is explained in terms of the monostable damped oscillator model.

  17. Aperiodic signals processing via parameter-tuning stochastic resonance in a photorefractive ring cavity

    NASA Astrophysics Data System (ADS)

    Li, Xuefeng; Cao, Guangzhan; Liu, Hongjun

    2014-04-01

    Based on solving numerically the generalized nonlinear Langevin equation describing the nonlinear dynamics of stochastic resonance by Fourth-order Runge-Kutta method, an aperiodic stochastic resonance based on an optical bistable system is numerically investigated. The numerical results show that a parameter-tuning stochastic resonance system can be realized by choosing the appropriate optical bistable parameters, which performs well in reconstructing aperiodic signals from a very high level of noise background. The influences of optical bistable parameters on the stochastic resonance effect are numerically analyzed via cross-correlation, and a maximum cross-correlation gain of 8 is obtained by optimizing optical bistable parameters. This provides a prospective method for reconstructing noise-hidden weak signals in all-optical signal processing systems.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

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

    PubMed

    Gudyma, Iurii; Maksymov, Artur; Dimian, Mihai

    2014-11-01

    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

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

    NASA Astrophysics Data System (ADS)

    Gudyma, Iurii; Maksymov, Artur; Dimian, Mihai

    2014-11-01

    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.

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

    NASA Technical Reports Server (NTRS)

    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

    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.

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

    Microsoft Academic Search

    Mark D. McDonnell; Derek Abbott

    2009-01-01

    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

  3. Entropic Resonant Activation and Stochastic Resonance Driven by Non-Gaussian Noise

    NASA Astrophysics Data System (ADS)

    Zeng, Chun-Hua; Wang, Hua

    2011-11-01

    The transition rate and stochastic resonance (SR) of a Brownian particle moving in a confined system under the presence of entropic barriers are investigated when the system is driven by non-Gaussian noise. The explicit expressions of the transition rate and the spectral power amplification (SPA) are obtained, respectively. The effects of the parameter q indicating the departure from the Gaussian noise and the correlation time ? of the non-Gaussian noise on the transition rate and the SPA are discussed. Research results show that: (i) The transition rate as a function of the noise strength exhibits a maximum. This maximum for transition rate identifies the phenomenon of entropic resonant activation (ERA), the parameter q and the noise correlation time ? weaken the ERA of the system; (ii) The curves of SPA appear a transition from one peak to double-peak, and then to one peak again as the noise correlation time ? of non-Gaussian noise increases.

  4. Stochastic resonance on weakly paced scale-free networks

    NASA Astrophysics Data System (ADS)

    Perc, Matjaž

    2008-09-01

    We study the impact of additive Gaussian noise and weak periodic forcing on the dynamics of a scale-free network of bistable overdamped oscillators. The periodic forcing is introduced to a single oscillator and therefore acts as a pacemaker trying to impose its rhythm on the whole ensemble. We show that an intermediate intensity of temporally and spatially uncorrelated noise is able to optimally assist the pacemaker in achieving this goal, thus providing evidence for stochastic resonance on weakly paced scale-free networks. Because of the inherent degree inhomogeneity of individual oscillators forming the scale-free network, the placement of the pacemaker within the network is thereby crucial. As two extremes, we consider separately the introduction of the pacemaker to the oscillator with the highest degree and to one of the oscillators having the lowest degree. In both cases the coupling strength plays a crucial role, since it determines to what extent the whole network will follow the pacemaker on the expense of a weaker correlation between the pacemaker and the units that are directly linked with the paced oscillator. Higher coupling strengths facilitate the global outreach of the pacemaker, but require higher noise intensities for the optimal response. In contrast, lower coupling strengths and comparatively low noise intensities localize the optimal response to immediate neighbors of the paced oscillator. If the pacemaker is introduced to the main hub, the transition between the locally and globally optimal responses is characterized by a double resonance that postulates the existence of an optimal coupling strength for the transmission of weak rhythmic activity across scale-free networks. We corroborate the importance of the inhomogeneous structure of scale-free networks by additionally considering regular networks of oscillators with different degrees of coupling.

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

    PubMed

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

    2013-03-01

    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

  6. Stochastic Resonance in Time-to-Contact Judgments

    NASA Astrophysics Data System (ADS)

    Ranjit, Manish; Gazula, Harshvardhan; Hsiang, Simon M.; Delucia, Patricia R.

    2015-04-01

    Stochastic resonance (SR) is a counterintuitive phenomenon in which additive noise enhances performance of a nonlinear system. Previous studies demonstrated SR effect on human tactile sensitivity by adding noise of same modality and cross modality. Similarly, enhancement of human hearing through additive noise has been studied. In this study, we investigate the effect of noise in visual perception, specifically time-to-contact (TTC) judgments. This study explores four research questions: (1) Does noise help in TTC judgments? (2) How does noise affect speed and accuracy of TTC judgments? (3) Does cross modal noise help in TTC judgments? (4) How does cross modal noise affect speed and accuracy of TTC judgments? Through simulation, we show that noise in optical cue can enhance weak signals. We also demonstrate that noise can improve speed of TTC judgments at the expense of accuracy. Similarly, we demonstrate SR by adding noise of cross modality. These findings provide plausible hypotheses regarding how much noise should be added to enhance TTC judgments.

  7. Stochastic Resonance in Ion Channels Characterized by Information Theory

    E-print Network

    Igor Goychuk; Peter Hanggi

    2000-01-19

    We identify a unifying measure for stochastic resonance (SR) in voltage dependent ion channels which comprises periodic (conventional), aperiodic and nonstationary SR. Within a simplest setting, the gating dynamics is governed by two-state conductance fluctuations, which switch at random time points between two values. The corresponding continuous time point process is analyzed by virtue of information theory. In pursuing this goal we evaluate for our dynamics the tau-information, the mutual information and the rate of information gain. As a main result we find an analytical formula for the rate of information gain that solely involves the probability of the two channel states and their noise averaged rates. For small voltage signals it simplifies to a handy expression. Our findings are applied to study SR in a potassium channel. We find that SR occurs only when the closed state is predominantly dwelled. Upon increasing the probability for the open channel state the application of an extra dose of noise monotonically deteriorates the rate of information gain, i.e., no SR behavior occurs.

  8. Entropic stochastic resonance without external force in oscillatory confined space

    NASA Astrophysics Data System (ADS)

    Ding, Huai; Jiang, Huijun; Hou, Zhonghuai

    2015-05-01

    We have studied the dynamics of Brownian particles in a confined geometry of dumbbell-shape with periodically oscillating walls. Entropic stochastic resonance (ESR) behavior, characterizing by a maximum value of the coherent factor Q at some optimal level of noise, is observed even without external periodic force in the horizontal direction, which is necessary for conventional ESR where the wall is static and the particle is subjected to the force. Interestingly, the ESR can be remarkably enhanced by the particle gravity G, in contrast to the conventional case. In addition, Q decreases (increases) with G in the small (large) noise limit, respectively, while it non-monotonically changes with G for moderate noise levels. We have applied an effective 1D coarsening description to illustrate such a nontrivial dependence on G, by investigating the property of the 1D effective potential of entropic nature and paying special attention to the excess part resulting from the boundary oscillation. Dependences of the ESR strength with other related parameters are also discussed.

  9. Entropic stochastic resonance without external force in oscillatory confined space.

    PubMed

    Ding, Huai; Jiang, Huijun; Hou, Zhonghuai

    2015-05-21

    We have studied the dynamics of Brownian particles in a confined geometry of dumbbell-shape with periodically oscillating walls. Entropic stochastic resonance (ESR) behavior, characterizing by a maximum value of the coherent factor Q at some optimal level of noise, is observed even without external periodic force in the horizontal direction, which is necessary for conventional ESR where the wall is static and the particle is subjected to the force. Interestingly, the ESR can be remarkably enhanced by the particle gravity G, in contrast to the conventional case. In addition, Q decreases (increases) with G in the small (large) noise limit, respectively, while it non-monotonically changes with G for moderate noise levels. We have applied an effective 1D coarsening description to illustrate such a nontrivial dependence on G, by investigating the property of the 1D effective potential of entropic nature and paying special attention to the excess part resulting from the boundary oscillation. Dependences of the ESR strength with other related parameters are also discussed. PMID:26001449

  10. Logical stochastic resonance in bistable system under ?-stable noise

    NASA Astrophysics Data System (ADS)

    Wang, Nan; Song, Aiguo

    2014-05-01

    In the presence of ?-stable noise, the logical stochastic resonance (LSR) phenomenon in a class of double well nonlinear system is investigated in this paper. LSR effect is obtained under ?-stable noise. The probability of getting correct logic outputs is used to evaluate LSR behavior. Four main results are presented. Firstly, in the optimal band of noise intensity, Gaussian white noise is considered a better choice than heavy tailed noise to obtain clean logic operation. But at weak noise background, the success probability of getting the right logic outputs is higher when the system is subjected to heavy tailed noise. Secondly, it is shown that over the entire range of noise variance, the asymmetric noise induced LSR performs better than that induced by the symmetric noise. Furthermore, we find which side the tail skews also affects the correct probability of LSR. At last, the fractional Fokker-Planck equation is presented to show when the characteristic exponent of ?-stable noise is less than 1, LSR behavior will not be obtained irrespective of the setting for other parameters.

  11. Stochastic resonance occurring in tactile sensation of human finger.

    PubMed

    Beceren, Kadir; Ohka, Masahiro; Miyaoka, Tetsu

    2013-01-01

    In this paper, we review the influence of external noise on human tactile sensation as outlined in prior and current studies. In the last few decades, researchers have found that, although noise is always considered detrimental, it provides the benefit of stochastic resonance (SR) phenomena. Based on previous studies, we investigate the effect of the SR phenomenon on human tactile sensation. In this context, we developed a system consisting of an experimental apparatus and a computer program, and performed a series of psychophysical experiments using different types of stimulus with normal vibration. The experimental results show that tactile sensation precision can be enhanced by an appropriate level of external noise. Furthermore, we introduce a neural network model composed of nonlinear neurons with a bi-stable equilibrium condition to clarify the result. Finally, we perform a sequence of psychophysical experiments with tangential vibration to clarify which conditions of vibration direction and stimulus size cause the strongest SR. The results show that the normal difference limen (DL) is significantly affected by stimulus point size. On the other hand, neither normal nor tangential DL is significantly affected by stimulus point size. Moreover, the characteristics of SR with normal vibration are quite different from those with tangential vibration. PMID:24110916

  12. Noise and stochastic resonance in voltage-gated ion channels

    PubMed Central

    Adair, Robert K.

    2003-01-01

    Using Monte Carlo techniques, I calculate the effects of internally generated noise on information transfer through the passage of action potential spikes along unmyelinated axons in a simple nervous system. I take the Hodgkin–Huxley (HH) description of Na and K channels in squid giant axons as the basis of the calculations and find that most signal transmission noise is generated by fluctuations in the channel open and closed populations. To bring the model closer to conventional descriptions in terms of thermal noise energy, kT, and to determine gating currents, I express the HH equations in the form of simple relations from statistical mechanics where the states are separated by a Gibbs energy that is modified by the action of the transmembrane potential on dipole moments held by the domains. Using the HH equations, I find that the output response (in the probability of action potential spikes) from small input potential pulses across the cell membrane is increased by added noise but falls off when the input noise becomes large, as in stochastic resonance models. That output noise response is sharply reduced by a small increase in the membrane polarization potential or a moderate increase in the channel densities. Because any reduction of noise incurs metabolic and developmental costs to an animal, the natural noise level is probably optimal and any increase in noise is likely to be harmful. Although these results are specific to signal transmission in unmyelinated axons, I suggest that the conclusions are likely to be general. PMID:14506291

  13. Anti-coherence and coherence resonance induced by nonlinear time delay in autonomous stochastic system

    NASA Astrophysics Data System (ADS)

    Zhu, Ping; Mei, Dong Cheng

    2014-05-01

    An autonomous stochastic system with nonlinear time-delayed feedback is investigated employing the stochastic simulation method. In the autonomous stochastic system with quadratic time-delayed feedback or under positive feedback, the nonlinear delay time fails to possess the role improving the noisy state of the system. In the autonomous stochastic system with cubic time-delayed feedback and under negative feedback, the nonlinear delay time can improve the noisy state, tuning the signal output, and generating incoherence and coherence maximization. We reveal a new kind of anti-coherence and coherence resonance phenomena induced by the nonlinear time delay in the autonomous stochastic system without external periodic force, discussing further the effects of the noise strength, the control parameter, and the feedback strength on anti-coherence and coherence resonance.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  15. Stochastic resonance can enhance information transmission in neural networks.

    PubMed

    Kawaguchi, Minato; Mino, Hiroyuki; Durand, Dominique M

    2011-07-01

    Stochastic resonance (SR) is a noise-induced phenomenon whereby signal detection can be improved by the addition of background noise in nonlinear systems. SR can also improve the transmission of information within single neurons. Since information processing in the brain is carried out by neural networks and noise is present throughout the brain, the hypothesis that noise and coupling play an important role in the control of information processing within a population of neurons to control was tested. Using computer simulations, we investigate the effect of noise on the transmission of information in an array of neurons, known as array-enhanced SR (AESR) in an interconnected population of hippocampal neurons. A subthreshold synaptic current (signal) modeled by a filtered homogeneous Poisson process was applied to a distal position in each of the apical dendrites, while background synaptic signals (uncorrelated noise) were presented to the midpoint in the basal dendrite. The transmembrane potentials were recorded in each cell of an array of CA1 neuron models, in order to determine spike firing times and to estimate the total and noise entropies from the spike firing times. The results show that the mutual information is maximized for a specific amplitude of uncorrelated noise, implying the presence of AESR. The results also show that the maximum mutual information increases with increased numbers of neurons and the strength of connections. Moreover, the relative levels of excitation and inhibition modulate the mutual information transfer. It is concluded that uncorrelated noise can enhance information transmission of subthreshold synaptic input currents in a population of hippocampal CA1 neuron models. Therefore, endogenous neural noise could play an important role in neural tissue by modulating the transfer of information across the network. PMID:21435971

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

    PubMed Central

    McDonnell, Mark D.; Abbott, Derek

    2009-01-01

    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

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

    NASA Technical Reports Server (NTRS)

    Schaffer, L.; Burns, J. A.

    1995-01-01

    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.

  18. Vestibular Evoked Myogenic Potentials in Patients With Acoustic Neuromas

    Microsoft Academic Search

    Toshihisa Murofushi; Masaki Matsuzaki; Masahiro Mizuno

    1998-01-01

    Background: To diagnose acoustic neuromas (ANs), the auditory brainstem response test and the caloric test have been used in addition to magnetic resonance imaging. The auditory brainstem response and the caloric tests mainly reflect functions of the auditory pathway, ie, the cochlear nerve and the superior vestibular nerve, respec- tively. Because the vestibular evoked myogenic poten- tial (VEMP) has been

  19. Lévy noises: Double stochastic resonance in a single-well potential

    NASA Astrophysics Data System (ADS)

    Dybiec, Bart?omiej

    2009-10-01

    We study properties of a single-well fourth-order potential perturbed by a periodically modulated stable noise. Periodic modulation of the stable noise asymmetry results in an occurrence of the dynamical hysteresis which is the manifestation of the stochastic resonance in the system at hand. We show that the single-well potential with time modulated stable driving is a minimalistic setup, allowing the occurrence of the stochastic resonance (as measured by the hysteresis loop area). Finally, we demonstrate that the observed stochastic resonance is of the double type, i.e., the system efficiency measured by the hysteresis loop area depends in a nonmonotonous way both on the scale parameter (noise intensity) and on the stability exponent characterizing tails asymptotic of noise pulses.

  20. Stochastic Resonance in a Simple Threshold Sensor System with Alpha Stable Noise

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-Rui; Kang, Yan-Mei; Xie, Yong

    2014-05-01

    We investigate the effect of alpha stable noise on stochastic resonance in a single-threshold sensor system by analytic deduction and stochastic simulation. It is shown that stochastic resonance occurs in the threshold system in alpha stable noise environment, but the resonant effect becomes weakened as the alpha stable index decreases or the skewness parameter of alpha stable distribution increases. In particular, for Cauchy noise a nonlinear relation among the optimal noise deviation parameter, the signal amplitude and the threshold is analytically obtained and illustrated by using the extreme value condition for the output signal-to-noise ratio. The results presented in this communication should have application in signal detection and image restoration in the non-Gaussian noisy environment.

  1. Relative stability of dynamical states and stochastic resonance in a sinusoidal potential.

    PubMed

    Reenbohn, W L; Mahato, Mangal C

    2013-09-01

    Recently, stochastic resonance was shown to occur in underdamped periodic potentials at frequencies (of the drive field) close to the natural frequency at the minima of the potentials. In these systems the particle trajectories are not arbitrary at low temperatures but follow the drive field with two definite mean phase differences depending on the initial conditions. The trajectories are thus found to be in only two stable dynamical states. The occurrence of stochastic resonance in the periodic potentials was explained as a consequence of the transitions between these two dynamical states as the temperature was increased. In the present work, we find the range of amplitudes of the drive field over which the dynamical states could be observed in a sinusoidal potential. The variation of the relative stability of the dynamical states as a function of drive-field amplitude is clarified by analyzing the nature of curves characterizing the stochastic resonance as the amplitude is varied within the range. PMID:24125249

  2. A review of methods for identifying stochastic resonance in simulations of single neuron models.

    PubMed

    McDonnell, Mark D; Iannella, Nicolangelo; To, Minh-Son; Tuckwell, Henry C; Jost, Jürgen; Gutkin, Boris S; Ward, Lawrence M

    2015-01-01

    Stochastic resonance (SR) is said to be observed when the presence of noise in a nonlinear system enables an output signal from the system to better represent some feature of an input signal than it does in the absence of noise. The effect has been observed in models of individual neurons, and in experiments performed on real neural systems. Despite the ubiquity of biophysical sources of stochastic noise in the nervous system, however, it has not yet been established whether neuronal computation mechanisms involved in performance of specific functions such as perception or learning might exploit such noise as an integral component, such that removal of the noise would diminish performance of these functions. In this paper we revisit the methods used to demonstrate stochastic resonance in models of single neurons. This includes a previously unreported observation in a multicompartmental model of a CA1-pyramidal cell. We also discuss, as a contrast to these classical studies, a form of 'stochastic facilitation', known as inverse stochastic resonance. We draw on the reviewed examples to argue why new approaches to studying 'stochastic facilitation' in neural systems need to be developed. PMID:25760433

  3. Stochastic resonance in Hodgkin-Huxley neuron induced by unreliable synaptic transmission.

    PubMed

    Guo, Daqing; Li, Chunguang

    2012-09-01

    We systematically investigate the stochastic dynamics of a single Hodgkin-Huxley neuron driven by stochastic excitatory and inhibitory input spikes via unreliable synapses in this paper. Based on the mean-filed theory, a novel intrinsic neuronal noise regulation mechanism stemming from unreliable synapses is presented. Our simulation results show that, under certain conditions, the stochastic resonance phenomenon is able to be induced by the unreliable synaptic transmission, which can be well explained by the theoretical prediction. To a certain degree, the results presented here provide insights into the functional roles of unreliable synapses in neural information processing. PMID:22687443

  4. Acute effects of stochastic resonance whole body vibration

    PubMed Central

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

    2013-01-01

    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

  5. Stochastic Resonance Modulates Neural Synchronization within and between Cortical Sources

    PubMed Central

    Ward, Lawrence M.; MacLean, Shannon E.; Kirschner, Aaron

    2010-01-01

    Neural synchronization is a mechanism whereby functionally specific brain regions establish transient networks for perception, cognition, and action. Direct addition of weak noise (fast random fluctuations) to various neural systems enhances synchronization through the mechanism of stochastic resonance (SR). Moreover, SR also occurs in human perception, cognition, and action. Perception, cognition, and action are closely correlated with, and may depend upon, synchronized oscillations within specialized brain networks. We tested the hypothesis that SR-mediated neural synchronization occurs within and between functionally relevant brain areas and thus could be responsible for behavioral SR. We measured the 40-Hz transient response of the human auditory cortex to brief pure tones. This response arises when the ongoing, random-phase, 40-Hz activity of a group of tuned neurons in the auditory cortex becomes synchronized in response to the onset of an above-threshold sound at its “preferred” frequency. We presented a stream of near-threshold standard sounds in various levels of added broadband noise and measured subjects' 40-Hz response to the standards in a deviant-detection paradigm using high-density EEG. We used independent component analysis and dipole fitting to locate neural sources of the 40-Hz response in bilateral auditory cortex, left posterior cingulate cortex and left superior frontal gyrus. We found that added noise enhanced the 40-Hz response in all these areas. Moreover, added noise also increased the synchronization between these regions in alpha and gamma frequency bands both during and after the 40-Hz response. Our results demonstrate neural SR in several functionally specific brain regions, including areas not traditionally thought to contribute to the auditory 40-Hz transient response. In addition, we demonstrated SR in the synchronization between these brain regions. Thus, both intra- and inter-regional synchronization of neural activity are facilitated by the addition of moderate amounts of random noise. Because the noise levels in the brain fluctuate with arousal system activity, particularly across sleep-wake cycles, optimal neural noise levels, and thus SR, could be involved in optimizing the formation of task-relevant brain networks at several scales under normal conditions. PMID:21179552

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

    E-print Network

    Changsong Zhou; C. -H. Lai

    2000-05-08

    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

  7. Stochastic resonance of a damped oscillator with frequency fluctuation driven by a periodic external force

    NASA Astrophysics Data System (ADS)

    Zhang, Ling-Ying; Jin, Guo-Xiang; Cao, Li; Wang, Zhi-Yun

    2012-12-01

    Considering a damped linear oscillator model subjected to a white noise with an inherent angular frequency and a periodic external driving force, we derive the analytic expression of the first moment of output response, and study the stochastic resonance phenomenon in a system. The results show that the output response of this system behaves as a simple harmonic vibration, of which the frequency is the same as the external driving frequency, and the variations of amplitude with the driving frequency and the inherent frequency present a bona fide stochastic resonance.

  8. Enhanced diffusion in conic channels by means of geometric stochastic resonance.

    PubMed

    Vazquez, M V; Valdes-Parada, F J; Dagdug, L; Alvarez-Ramirez, J

    2011-11-01

    Geometric stochastic resonance of Brownian particles diffusing across a converging conic channel subject to oscillating forces is studied in this paper. Conic channel geometries have been previously considered as a model for transport of particles in biological membranes, zeolites, and nanostructures. For this system, a broad excess peak of the effective diffusion above the free diffusion limit is exhibited over a wide range of frequencies, suggesting a synchronization effect in the confining geometry as particles respond to the periodic modulation of the external force. This indicates that the geometric stochastic resonance effect with unbiased ac forces can be exploited for improving the transport of particles in complex geometries. PMID:22070287

  9. Stochastic resonance in the two-dimensional q-state clock models

    NASA Astrophysics Data System (ADS)

    Park, Hye Jin; Baek, Seung Ki; Kim, Beom Jun

    2014-03-01

    We numerically study stochastic resonance in the two-dimensional q-state clock models from q =2 to 7 under a weak oscillating magnetic field. As in the mean-field case, we observe double resonance peaks, but the detailed response strongly depends on the direction of the field modulation for q ?5 where the quasiliquid phase emerges. We explain this behavior in terms of free-energy landscapes on the two-dimensional magnetization plane.

  10. Stochastic resonance in the two-dimensional q-state clock models.

    PubMed

    Park, Hye Jin; Baek, Seung Ki; Kim, Beom Jun

    2014-03-01

    We numerically study stochastic resonance in the two-dimensional q-state clock models from q=2 to 7 under a weak oscillating magnetic field. As in the mean-field case, we observe double resonance peaks, but the detailed response strongly depends on the direction of the field modulation for q?5 where the quasiliquid phase emerges. We explain this behavior in terms of free-energy landscapes on the two-dimensional magnetization plane. PMID:24730819

  11. The effects of time delay on the stochastic resonance in feed-forward-loop neuronal network motifs

    NASA Astrophysics Data System (ADS)

    Liu, Chen; Wang, Jiang; Yu, Haitao; Deng, Bin; Tsang, K. M.; Chan, W. L.; Wong, Y. K.

    2014-04-01

    The dependence of stochastic resonance in the feed-forward-loop neuronal network motifs on the noise and time delay are studied in this paper. By computational modeling, Izhikevich neuron model with the chemical coupling is used to build the triple-neuron feed-forward-loop motifs with all possible motif types. Numerical results show that the correlation between the periodic subthreshold signal's frequency and the dynamical response of the network motifs is resonantly dependent on the intensity of additive spatiotemporal noise. Interestingly, the excitatory intermediate neuron could induce intermittent stochastic resonance, whereas the inhibitory one weakens its influence on the intermittent mode. More importantly, it is found that the increasing delays can induce the intermittent appearance of regions of stochastic resonance. Based on the effects of the time delay on the stochastic resonance, the reasons and conditions of such intermittent resonance phenomenon are analyzed.

  12. Review of book vestibular crises

    NASA Technical Reports Server (NTRS)

    Blagoveshchenskaya, N. S.

    1980-01-01

    The etiology, pathogenesis, clinical practice, treatment and rehabilitation of patients with vestibular crises is discussed. Classifications for vestibular disorders are given. Information on the frequency of vestibular crises is given.

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

    SciTech Connect

    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

    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.

  14. Channel noise enhances signal detectability in a model of acoustic neuron through the stochastic resonance paradigm

    Microsoft Academic Search

    M. Liberti; A. Paffi; F. Maggio; A. De Angelis; F. Apollonio; G. d'Inzeo

    2009-01-01

    A number of experimental investigations have evidenced the extraordinary sensitivity of neuronal cells to weak input stimulations, including electromagnetic (EM) fields. Moreover, it has been shown that biological noise, due to random channels gating, acts as a tuning factor in neuronal processing, according to the stochastic resonant (SR) paradigm. In this work the attention is focused on noise arising from

  15. Array enhanced logical stochastic resonance in the presence of delta correlated noise

    Microsoft Academic Search

    Lei Zhang; Yanchang Xiao; Xiangping Wu

    2011-01-01

    In the presence of noise floor, we investigate the logical stochastic resonance phenomenon in a parallel array consisting of bistable devices, which is driven by various cycling combinations of logic inputs. The probability of the correct logic output is calculated according to true table of logic relationships. In contrast with a single system, the significant logic response can be extracted

  16. Creating morphable logic gates using logical stochastic resonance in an engineered gene network

    Microsoft Academic Search

    Anna Dari; Behnam Kia; Adi R. Bulsara; William Ditto

    2011-01-01

    The idea of Logical Stochastic Resonance is adapted and applied to an autoregulatory gene network in the bacteriophage lambda. This biological logic gate can emulate or morph the AND and OR gates, through varying internal system parameters, in a noisy background. Such logic gates afford intriguing possibilities in the realization of engineered genetic networks, in which the function of the

  17. Non-Dynamical Stochastic Resonance: Theory and Experiments with White and Arbitrarily Coloured Noise

    Microsoft Academic Search

    Z. Gingl; L. B. Kiss; F. Moss

    1995-01-01

    We describe the simplest system which shows stochastic resonance. Theoretical results for white and (almost) arbitrarily coloured noise are presented. The new system has new, unique properties which originate from its non-dynamical character; for example, the strength and phase shift of periodic response of the system is independent of the frequency. Experiments have been carried out with the following noise

  18. Weak signal detection based on stochastic resonance combining with PSO algorithm

    Microsoft Academic Search

    Zhefei Hou; Jie Yang; Kecheng Wang; Yunpeng Wang

    2009-01-01

    In order to detect a weak signal under the condition of intensive noise, the signal and additive white noise were used as input of a bistable stochastic resonance (SR) system. The noise intensity and the system parameters were adjusted adaptively with particle swarm optimization (PSO) algorithm by examining the SR effect on output signal-to-noise ratio (SNR). An improved numerical solution

  19. Enhancement of information transmission with stochastic resonance in hippocampal CA1 neuron models.

    PubMed

    Mino, Hiroyuki; Durand, Dominique M; Kawaguchi, Minato

    2006-01-01

    Stochastic resonance (SR) has been shown to enhance the signal to noise ratio or detection of signals in neurons. It is not yet clear how this effect of SR on the signal to noise ratio affects signal processing in neural networks. In this paper, we test the hypothesis that SR can improve information transmission in the hippocampus. From spike firing times recorded at the soma, the inter spike intervals were generated and then "total" and "noise" entropies were estimated to obtain the mutual information and information rate of the spike trains. The results show that the information rate reached a maximum value at a specific amplitude of the background noise, implying that the stochastic resonance can improve the information transmission in the CA1 neuron model. Furthermore, the results also show that the effect of stochastic resonance tended to decrease as the intensity of the random sub-threshold spike trains (signal) (more than 20 l/s) approached to that of the background noise (100 l/s). In conclusion, the computation results that the stochastic resonance can improve information processing in the hippocampal CA1 neuron model in which the intensity of the random sub-threshold spike trains was set at 5-20 l/s. PMID:17945870

  20. Stochastic resonance can enhance information transmission of supra-threshold neural signals.

    PubMed

    Kawaguchi, Minato; Mino, Hiroyuki; Momose, Keiko; Durand, Dominique M

    2009-01-01

    Stochastic resonance (SR) has been shown to improve detection of sub-threshold signals with additive uncor-related background noise, not only in a single hippocampal CA1 neuron model, but in a population of hippocampal CA1 neuron models (Array-Enhanced Stochastic Resonance; AESR). However, most of the information in the CNS is transmitted through supra-threshold signals and the effect of stochastic resonance in neurons on these signals is unknown. Therefore, we investigate through computer simulations whether information transmission of supra-threshold input signal can be improved by uncorrelated noise in a population of hippocampal CA1 neuron models by supra-threshold stochastic resonance (SSR). The mutual information was estimated as an index of information transmission via total and noise entropies from the inter-spike interval (ISI) histograms of the spike trains generated by gathering each of spike trains in a population of hippocampal CA1 neuron models at N = 1, 2, 4, 10, 20 and 50. It was shown that the mutual information was maximized at a specific amplitude of uncorrelated noise, i.e., a typical curve of SR was observed when the number of neurons was greater than 10 with SSR. However, SSR did not affect the information transfer with a small number of neurons. In conclusion, SSR may play an important role in processing information such as memory formation in a population of hippocampal neurons. PMID:19964714

  1. Temporal correlations in postural sway moderate effects of stochastic resonance on postural stability.

    PubMed

    Kelty-Stephen, Damian G; Dixon, James A

    2013-02-01

    The present work documents reanalysis of previous research by Priplata and colleagues (Priplata et al., 2002) into the effects of subthreshold vibratory stimulation to the plantar surface of the foot on postural stability during quiet standing. In stochastic resonance, stimulating a nonlinear system with noise can promote system stability. Stochastic resonance has been proposed to have clinical applications as an intervention that might help to stabilize posture. Insoles designed to stimulate the plantar surface of the foot with uncorrelated white-noise fluctuations have been shown to reduce a number of standard measures of postural variability. An important remaining concern is that the efficacy of stochastic-resonance applications is subject to strong individual differences. Our reanalysis of data from Priplata et al.'s original study provides evidence that effects of uncorrelated fluctuations in subthreshold vibratory stimulation are moderated by temporally correlated fluctuations in postural sway. We suggest how future development might capitalize on this finding to fine-tune existing stochastic-resonance applications to posture. PMID:23317679

  2. Large deviations for diffusions with time periodic drift and stochastic resonance

    E-print Network

    Imkeller, Peter

    Large deviations for diffusions with time periodic drift and stochastic resonance Samuel Herrmann: a slow external periodic perturbation of period T and a small Gaussian random perturbation of intensity- tion b(q, T) describes the force associated with a double well potential possessing two stable

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

    E-print Network

    Imkeller, Peter

    Large deviations for di#usions with time periodic drift and stochastic resonance Samuel Herrmann: a slow external periodic perturbation of period T and a small Gaussian random perturbation of intensity the force associated with a double well potential possessing two stable temperature states which represent

  4. Vestibular evoked myogenic potential in vestibular neuritis

    Microsoft Academic Search

    Giuseppe Nola; Luca Guastini; Barbara Crippa; Marco Deiana; Renzo Mora; Giovanni Ralli

    This study wants to show the diagnostic value of vestibular evoked myogenic potential (VEMP) in the diagnosis of vestibular\\u000a neuritis (VN), independently of the caloric test results. Twenty patients were enrolled with acute vertigo caused by VN. VEMP\\u000a was tested with the binaural simultaneous stimulation method. Surface electromyographic activity was recorded in the supine\\u000a patients from symmetrical sites over the

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

    PubMed

    Lu, Qiang; Tian, Juan

    2014-06-01

    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

  6. Coherent and stochastic contributions of compound resonances in atomic processes: Electron recombination, photoionization, and scattering

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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 the independent-resonance approximation) leads to a coherent contribution, which determines the energy-averaged total cross sections of electron- and photon-induced reactions obtained using the optical theorem. In contrast, the partial cross sections (e.g., electron recombination or photon Raman scattering) are dominated by the stochastic contributions. Thus, the optical theorem provides a link between the stochastic and coherent contributions of the compound resonances. Similar conclusions are valid for reactions via compound states in molecules and nuclei.

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

    SciTech Connect

    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

    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.

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

    PubMed

    Guzmán-Lastra, Francisca; Soto, Rodrigo

    2012-09-01

    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. PMID:23031055

  9. Time delay induced transition of gene switch and stochastic resonance in a genetic transcriptional regulatory model

    PubMed Central

    2012-01-01

    Background Noise, nonlinear interactions, positive and negative feedbacks within signaling pathways, time delays, protein oligomerization, and crosstalk between different pathways are main characters in the regulatory of gene expression. However, only a single noise source or only delay time in the deterministic model is considered in the gene transcriptional regulatory system in previous researches. The combined effects of correlated noise and time delays on the gene regulatory model still remain not to be fully understood. Results The roles of time delay on gene switch and stochastic resonance are systematically explored based on a famous gene transcriptional regulatory model subject to correlated noise. Two cases, including linear time delay appearing in the degradation process (case I) and nonlinear time delay appearing in the synthesis process (case II) are considered, respectively. For case I: Our theoretical results show that time delay can induce gene switch, i.e., the TF-A monomer concentration shifts from the high concentration state to the low concentration state ("on"?"off"). With increasing the time delay, the transition from "on" to "off" state can be further accelerated. Moreover, it is found that the stochastic resonance can be enhanced by both the time delay and correlated noise intensity. However, the additive noise original from the synthesis rate restrains the stochastic resonance. It is also very interesting that a resonance bi-peaks structure appears under large additive noise intensity. The theoretical results by using small-delay time-approximation approach are consistent well with our numerical simulation. For case II: Our numerical simulation results show that time delay can also induce the gene switch, however different with case I, the TF-A monomer concentration shifts from the low concentration state to the high concentration state ("off"?"on"). With increasing time delay, the transition from "on" to "off" state can be further enhanced. Moreover, it is found that the stochastic resonance can be weaken by the time delay. Conclusions The stochastic delay dynamic approach can identify key physiological control parameters to which the behavior of special genetic regulatory systems is particularly sensitive. Such parameters might provide targets for pharmacological intervention. Thus, it would be highly interesting to investigate if similar experimental techniques could be used to bring out the delay-induced switch and stochastic resonance in the stochastic gene transcriptional regulatory process. PMID:23046840

  10. Non-Markovian stochastic jump processes. II. The case of resonance fluorescence

    SciTech Connect

    Kofman, A.G.; Zaibel, R. (Department of Chemical Physics, Weizmann Institute of Science, 76100 Rehovot, Israel (IL)); Levine, A.M. (Department of Chemical Physics, Weizmann Institute of Science, 76100 Rehovot (Israel) Department of Applied Science, College of Staten Island, City University of New York, Staten Island, NY (USA)); Prior, Y. (Department of Chemical Physics, Weizmann Institute of Science, 76100 Rehovot (Israel))

    1990-06-01

    Strong laser fields, when tuned on resonance to an atomic (molecular) transition, give rise to the well-known triplet of resonance fluorescence. The laser field is normally assumed to be strong and monochromatic, even though the spectrum of real lasers is never a {delta} function. A standard way to treat laser fluctuations has been to assume a well-defined nominal frequency and a randomly fluctuating phase. Recently we introduced the generalized jump model (GJM) for correlated phase fluctuations, where correlated phase jumps are considered, leading to Markovian as well as non-Markovian stochastic behavior. In the GJM, each phase jump may be correlated to the previous jump, and the degree of correlation, the typical jump size, and the mean time between jumps are the three parameters defining the stochastic character of the laser field. In this paper we apply the GJM model to the case of resonance fluorescence from an atom excited by a stochastic field. The standard'' Mollow triplet is obtained in the monochromatic limit of small jumps, and several new predictions are made in the different limits of the stochastic parameters. In the small-jump limit, a new field effect'' is predicted. The spectral line shape and the triplet separation deviate from the Mollow predictions for a monochromatic field in a substantial way, giving rise to observable differences.

  11. Pseudo resonance induced quasi-periodic behavior in stochastic threshold dynamics

    E-print Network

    Peter D. Ditlevsen; Holger Braun

    2011-06-07

    Here we present a simple stochastic threshold model consisting of a deterministic slowly decaying term and a fast stochastic noise term. The process shows a pseudo-resonance, in the sense that for small and large intensities of the noise the signal is irregular and the distribution of threshold crossings is broad, while for a tuned intermediate value of noise intensity the signal becomes quasi-periodic and the distribution of threshold crossings is narrow. The mechanism captured by the model might be relevant for explaining apparent quasi-periodicity of observed climatic variations where no internal or external periodicities can be identified.

  12. Thermally induced synchronization and stochastic resonance between magnetization regimes in spin-transfer nano-oscillators

    NASA Astrophysics Data System (ADS)

    d'Aquino, M.; Serpico, C.; Bonin, R.; Bertotti, G.; Mayergoyz, I. D.

    2012-04-01

    The thermally induced synchronization of transitions between different magnetization regimes with weak ac-injected spin-polarized current is considered for a spin-valve-like magnetic nano-system, where magnetization dynamics is described by the Landau-Lifshitz-Slonczewski equation. We apply suitable averaging techniques and derive a non-autonomous stochastic differential equation for the free energy. By using this equation, we demonstrate that synchronization of thermal transitions with weak ac excitation is ascribed to a general form of stochastic resonance. Numerical computations confirm the accuracy of the theory.

  13. Vestibular sensitivity in vestibular migraine: VEMPs and motion sickness susceptibility

    Microsoft Academic Search

    Marion Ingeborg Boldingh; Unn Ljøstad; Åse Mygland; Per Monstad

    2011-01-01

    Background: Vestibular migraine (VM) has gained recognition as a distinct clinical entity in recent years. The pathophysiology is unclear. Vestibular evoked myogenic potential (VEMP) is a validated method to test the vestibulocollic reflex and peripheral vestibular hypersensitivity to noise. The aim of our study was to evaluate the vestibular function and sensitivity in a series of VM patients in comparison

  14. Stochastic resonance on paced genetic regulatory small-world networks: effects of asymmetric potentials

    NASA Astrophysics Data System (ADS)

    Perc, M.

    2009-05-01

    We study the phenomenon of stochastic resonance on small-world networks consisting of bistable genetic regulatory units, whereby the external subthreshold periodic forcing is introduced as a pacemaker trying to impose its rhythm on the whole network through the single unit to which it is introduced. Without the addition of additive spatiotemporal noise, however, the whole network remains forever trapped in one of the two stable steady states of the local dynamics. We show that the correlation between the frequency of subthreshold pacemaker activity and the response of the network is resonantly dependent on the intensity of additive noise. The reported pacemaker driven stochastic resonance depends significantly on the asymmetry of the two potential wells characterizing the bistable dynamics, which can be tuned via a single system parameter. In particular, we show that the ratio between the clustering coefficient and the characteristic path length is a suitable quantity defining the ability of a small-world network to facilitate the outreach of the pacemaker-emitted subthreshold rhythm, but only if the asymmetry between the potentials is practically negligible. In case of substantially asymmetric potentials the impact of the small-world topology is less profound and cannot warrant an enhancement of stochastic resonance by units that are located far from the pacemaker.

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

    PubMed

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

    2011-12-01

    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. PMID:22225376

  16. Cellular Mechanisms of Vestibular Compensation

    Microsoft Academic Search

    Janet M. Paterson; John R. W. Menzies; Filip Bergquist; Mayank B. Dutia

    2006-01-01

    Vestibular compensation, the behavioral recovery that takes place after unilateral vestibular deafferentation, is a complex and multifactorial process involving synaptic and neuronal plasticity in the vestibular nuclei, cerebellum and related structures. Recent experimental evidence suggests that changes in the intrinsic properties of the vestibular nucleus neurons, changes in the efficacy of their inhibitory synaptic inputs, activity-dependent rewiring of synaptic connectivity

  17. Stochastic resonance in an RF SQUID with shunted ScS junction

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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.

  18. Central vestibular dysfunction in an otorhinolaryngological vestibular unit: incidence and diagnostic strategy.

    PubMed

    Mostafa, Badr E; Kahky, Ayman O El; Kader, Hisham M Abdel; Rizk, Michael

    2014-07-01

    Introduction?Vertigo can be due to a variety of central and peripheral causes. The relative incidence of central causes is underestimated. This may have an important impact of the patients' management and prognosis. Objective?The objective of this work is to determine the incidence of central vestibular disorders in patients presenting to a vestibular unit in a tertiary referral academic center. It also aims at determining the best strategy to increase the diagnostic yield of the patients' visit. Methods?This is a prospective observational study on 100 consecutive patients with symptoms suggestive of vestibular dysfunction. All patients completed a structured questionnaire and received bedside and vestibular examination and neuroimaging as required. Results?There were 69 women and 31 men. Their ages ranged between 28 and 73 (mean 42.48 years). Provisional videonystagmography (VNG) results were: 40% benign paroxysmal positional vertigo (BPPV), 23% suspicious of central causes, 18% undiagnosed, 15% Meniere disease, and 4% vestibular neuronitis. Patients with an unclear diagnosis or central features (41) had magnetic resonance imaging (MRI) and Doppler studies. Combining data from history, VNG, and imaging studies, 23 patients (23%) were diagnosed as having a central vestibular lesion (10 with generalized ischemia/vertebra basilar insufficiency, 4 with multiple sclerosis, 4 with migraine vestibulopathy, 4 with phobic postural vertigo, and 1 with hyperventilation-induced nystagmus). Conclusions?Combining a careful history with clinical examination, VNG, MRI, and Doppler studies decreases the number of undiagnosed cases and increases the detection of possible central lesions. PMID:25992098

  19. Stochastic Transport Modeling of Resonant Magnetic Perturbations in DIII-D

    SciTech Connect

    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

    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.

  20. Stochastic transport modeling of resonant magnetic perturbations in DIII-D

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

    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 needed, possible explanations include plasma screening of resonant perturbations, limitations of the treatment of the edge as a fluid, or insufficient understanding of stochastic heat transport.

  1. Dynamical states, stochastic resonance, and ratchet effect in a biharmonically driven sinusoidal potential

    NASA Astrophysics Data System (ADS)

    Reenbohn, W. L.; Mahato, Mangal C.

    2015-05-01

    Two stable dynamical states of trajectories of an underdamped particle, under appropriate conditions, appear naturally in a sinusoidal potential when driven by a low-amplitude biharmonic external field. These states are quite stable at low temperatures but make transitions between them as the temperature is raised. The proper choice of the biharmonic drive makes it possible for the system to show, at the same time, both the phenomena of stochastic resonance and the ratchet effect. The ratchet effect, in this case a consequence of the biharmonic drive, is obtained over a large domain of parameter space. However, stochastic resonance can be obtained only over a restricted (sub)domain of parameter space, and it owes its existence largely to the existence of the two dynamical states.

  2. Stochastic resonant damping in a noisy monostable system: theory and experiment.

    PubMed

    Volpe, Giovanni; Perrone, Sandro; Rubi, J Miguel; Petrov, Dmitri

    2008-05-01

    Usually in the presence of a background noise an increased effort put in controlling a system stabilizes its behavior. Rarely it is thought that an increased control of the system can lead to a looser response and, therefore, to a poorer performance. Strikingly there are many systems that show this weird behavior; examples can be drawn form physical, biological, and social systems. Until now no simple and general mechanism underlying such behaviors has been identified. Here we show that such a mechanism, named stochastic resonant damping, can be provided by the interplay between the background noise and the control exerted on the system. We experimentally verify our prediction on a physical model system based on a colloidal particle held in an oscillating optical potential. Our result adds a tool for the study of intrinsically noisy phenomena, joining the many constructive facets of noise identified in the past decades-for example, stochastic resonance, noise-induced activation, and Brownian ratchets. PMID:18643026

  3. Stochastic resonant damping in a noisy monostable system: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Volpe, Giovanni; Perrone, Sandro; Rubi, J. Miguel; Petrov, Dmitri

    2008-05-01

    Usually in the presence of a background noise an increased effort put in controlling a system stabilizes its behavior. Rarely it is thought that an increased control of the system can lead to a looser response and, therefore, to a poorer performance. Strikingly there are many systems that show this weird behavior; examples can be drawn form physical, biological, and social systems. Until now no simple and general mechanism underlying such behaviors has been identified. Here we show that such a mechanism, named stochastic resonant damping, can be provided by the interplay between the background noise and the control exerted on the system. We experimentally verify our prediction on a physical model system based on a colloidal particle held in an oscillating optical potential. Our result adds a tool for the study of intrinsically noisy phenomena, joining the many constructive facets of noise identified in the past decades—for example, stochastic resonance, noise-induced activation, and Brownian ratchets.

  4. Parameter-induced stochastic resonance based on spectral entropy and its application to weak signal detection

    NASA Astrophysics Data System (ADS)

    Zhang, Jinjing; Zhang, Tao

    2015-02-01

    The parameter-induced stochastic resonance based on spectral entropy (PSRSE) method is introduced for the detection of a very weak signal in the presence of strong noise. The effect of stochastic resonance on the detection is optimized using parameters obtained in spectral entropy analysis. Upon processing employing the PSRSE method, the amplitude of the weak signal is enhanced and the noise power is reduced, so that the frequency of the signal can be estimated with greater precision through spectral analysis. While the improvement in the signal-to-noise ratio is similar to that obtained using the Duffing oscillator algorithm, the computational cost reduces from O(N2) to O(N). The PSRSE approach is applied to the frequency measurement of a weak signal made by a vortex flow meter. The results are compared with those obtained applying the Duffing oscillator algorithm.

  5. Stochastic Resonance in a Fractional Oscillator with Random Mass and Random Frequency

    NASA Astrophysics Data System (ADS)

    Lin, Li-Feng; Chen, Cong; Zhong, Su-Chuan; Wang, Hui-Qi

    2015-04-01

    For a fractional linear oscillator subjected to two multiplicative dichotomous noises and a additive fractional Gaussian noise and driven by a periodic signal, we study the stochastic resonance (SR) in this paper. Using (fractional) Shapiro-Loginov formula and the Laplace transformation technique, we acquire the exact expression of the first-order moment of the system's steady response. Meanwhile, we discuss the evolutions of the output amplitude with frequency of the periodic signal, noise parameters, fractional order, and friction coefficient. We find that SR in the wide sense existing in this system. Specially, the evolution of the output amplitude with frequency of the periodic signal presents one-peak oscillation and two-peak oscillation. Moreover, the friction coefficient can induce stochastic multi-resonance.

  6. Parameter-induced stochastic resonance based on spectral entropy and its application to weak signal detection.

    PubMed

    Zhang, Jinjing; Zhang, Tao

    2015-02-01

    The parameter-induced stochastic resonance based on spectral entropy (PSRSE) method is introduced for the detection of a very weak signal in the presence of strong noise. The effect of stochastic resonance on the detection is optimized using parameters obtained in spectral entropy analysis. Upon processing employing the PSRSE method, the amplitude of the weak signal is enhanced and the noise power is reduced, so that the frequency of the signal can be estimated with greater precision through spectral analysis. While the improvement in the signal-to-noise ratio is similar to that obtained using the Duffing oscillator algorithm, the computational cost reduces from O(N(2)) to O(N). The PSRSE approach is applied to the frequency measurement of a weak signal made by a vortex flow meter. The results are compared with those obtained applying the Duffing oscillator algorithm. PMID:25725879

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

    PubMed Central

    Kashimori, Y; Funakubo, H; Kambara, T

    1998-01-01

    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

  8. A Modified Adaptive Stochastic Resonance for Detecting Faint Signal in Sensors

    PubMed Central

    Huang, Qi; Liu, Jun; Li, Hengwei

    2007-01-01

    In this paper, an approach is presented to detect faint signals with strong noises in sensors by stochastic resonance (SR). We adopt the power spectrum as the evaluation tool of SR, which can be obtained by the fast Fourier transform (FFT). Furthermore, we introduce the adaptive filtering scheme to realize signal processing automatically. The key of the scheme is how to adjust the barrier height to satisfy the optimal condition of SR in the presence of any input. For the given input signal, we present an operable procedure to execute the adjustment scheme. An example utilizing one audio sensor to detect the fault information from the power supply is given. Simulation results show that the modified stochastic resonance scheme can effectively detect fault signal with strong noise.

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

    NASA Astrophysics Data System (ADS)

    Arathi, S.; Rajasekar, S.

    2014-12-01

    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.

  10. Effects of time delay and random rewiring on the stochastic resonance in excitable small-world neuronal networks.

    PubMed

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

    2013-05-01

    The effects of time delay and rewiring probability on stochastic resonance and spatiotemporal order in small-world neuronal networks are studied in this paper. Numerical results show that, irrespective of the pacemaker introduced to one single neuron or all neurons of the network, the phenomenon of stochastic resonance occurs. The time delay in the coupling process can either enhance or destroy stochastic resonance on small-world neuronal networks. In particular, appropriately tuned delays can induce multiple stochastic resonances, which appear intermittently at integer multiples of the oscillation period of the pacemaker. More importantly, it is found that the small-world topology can significantly affect the stochastic resonance on excitable neuronal networks. For small time delays, increasing the rewiring probability can largely enhance the efficiency of pacemaker-driven stochastic resonance. We argue that the time delay and the rewiring probability both play a key role in determining the ability of the small-world neuronal network to improve the noise-induced outreach of the localized subthreshold pacemaker. PMID:23767608

  11. Stochastic resonance in an ion channel following the non-Arrhenius gating rate

    Microsoft Academic Search

    Yong Woon Parc; Duk-Su Koh; Wokyung Sung

    2009-01-01

    Stochastic resonance (SR) is a novel cooperative phenomenon occurring in\\u000a nonlinear systems due to coupling of an ambient noise and an external\\u000a signal. Biological systems may use SR mechanism to detect the signal\\u000a efficiently from an external environment. A number of studies have addressed\\u000a the SR in artificial ion channels considering external voltages as noises.\\u000a More important than these external

  12. Work and dissipation fluctuations near the stochastic resonance of a colloidal particle

    NASA Astrophysics Data System (ADS)

    Jop, P.; Petrosyan, A.; Ciliberto, S.

    2008-03-01

    We study experimentally the fluctuations of the injected and dissipated energy in a system of a colloidal particle trapped in a double-well potential periodically modulated by an external perturbation. The work done by the external force and the dissipated energy are measured close to the stochastic resonance where the injected power is maximum. We show that the steady-state fluctuation theorem holds in this system.

  13. Stochastic resonance in bistable confining potentials. On the role of confinement

    NASA Astrophysics Data System (ADS)

    Heinsalu, E.; Patriarca, M.; Marchesoni, F.

    2009-05-01

    We study the effects of the confining conditions on the occurrence of stochastic resonance (SR) in continuous bistable systems. We model such systems by means of double-well potentials that diverge like |x|q for |x|??. For super-harmonic (hard) potentials with q > 2 the SR peak sharpens with increasing q, whereas for sub-harmonic (soft) potentials, q < 2, it gets suppressed.

  14. Modeling electromagnetic fields detectability in a HH-like neuronal system: stochastic resonance and window behavior

    Microsoft Academic Search

    Matteo Giannì; Micaela Liberti; Francesca Apollonio; Guglielmo D’Inzeo

    2006-01-01

    Noise has already been shown to play a constructive role in neuronal processing and reliability, according to stochastic resonance\\u000a (SR). Here another issue is addressed, concerning noise role in the detectability of an exogenous signal, here representing\\u000a an electromagnetic (EM) field. A Hodgkin–Huxley like neuronal model describing a myelinated nerve fiber is proposed and validated,\\u000a excited with a suprathreshold stimulation.

  15. Far from Equilibrium Percolation, Stochastic and Shape Resonances in the Physics of Life

    PubMed Central

    Poccia, Nicola; Ansuini, Alessio; Bianconi, Antonio

    2011-01-01

    Key physical concepts, relevant for the cross-fertilization between condensed matter physics and the physics of life seen as a collective phenomenon in a system out-of-equilibrium, are discussed. The onset of life can be driven by: (a) the critical fluctuations at the protonic percolation threshold in membrane transport; (b) the stochastic resonance in biological systems, a mechanism that can exploit external and self-generated noise in order to gain efficiency in signal processing; and (c) the shape resonance (or Fano resonance or Feshbach resonance) in the association and dissociation processes of bio-molecules (a quantum mechanism that could play a key role to establish a macroscopic quantum coherence in the cell). PMID:22072921

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  17. Vibrational and stochastic resonances in two coupled overdamped anharmonic oscillators driven by an amplitude modulated force

    NASA Astrophysics Data System (ADS)

    Gandhimathi, V. M.; Rajasekar, S.

    2007-12-01

    Vibrational and stochastic resonances (VR and SR) in two coupled overdamped anharmonic oscillators subjected to an amplitude modulated force (f + 2 g \\cos \\Omega t) \\sin \\omega t, \\Omega \\gg \\omega are numerically studied. When both low- and high-frequency components are included the system show hysteresis and VR behaviour in the absence of a noise term. The resonance dynamics is characterized using response amplitude, phase portrait and mean residence time. We show the occurrence of SR by varying the noise intensity D in the presence of an amplitude modulated signal. High-frequency periodic force induced VR and noise-induced SR show certain similarities and differences.

  18. Stochastic resonance and heat fluctuations in a driven double-well system

    NASA Astrophysics Data System (ADS)

    Sahoo, Mamata; Saikia, Shantu; Mahato, Mangal C.; Jayannavar, A. M.

    2008-11-01

    We study a periodically driven (symmetric as well as asymmetric) double-well potential system at finite temperature. We show that mean heat loss by the system to the environment (bath) per period of the applied field is a good quantifier of stochastic resonance. It is found that the heat fluctuations over a single period are always larger than the work fluctuations. The observed distributions of work and heat exhibit pronounced asymmetry near resonance. The heat loss over a large number of periods satisfies the conventional steady-state fluctuation theorem.

  19. Stochastic resonance induced by a multiplicative periodic signal in a logistic growth model with correlated noises

    NASA Astrophysics Data System (ADS)

    Bai, Chunyan; Du, Luchun; Mei, Dongcheng

    2009-09-01

    The stochastic resonance (SR) phenomenon induced by a multiplicative periodic signal in a logistic growth model with correlated noises is studied by using the theory of signal-to-noise ratio ( SNR) in the adiabatic limit. The expressions of the SNR are obtained. The effects of multiplicative noise intensity ? and additive noise intensity D, and correlated intensity ? on the SNR are discussed respectively. It is found that the existence of a maximum in the SNR is the identifying characteristic of the SR phenomena. In comparison with the SR induced by additive periodic signal, some new features are found: (1) When SNR as a function of ? for fixed ratio of ? and D, the varying of ? can induce a stochastic multi-resonance, and can induce a re-entrant transition of the peaks in SNR vs ?; (2) There exhibits a doubly critical phenomenon for SNR vs D and ?, i.e., the increasing of D (or ?) can induce the critical phenomenon for SNR with respect to ? (or D); (3) The doubly stochastic resonance effect appears when ? and D are simultaneously varying in SNR, i.e., the increment of one noise intensity can help the SR on another noise intensity come forth.

  20. Stochastic resonance induced by a multiplicative periodic signal in a logistic growth model with correlated noises

    NASA Astrophysics Data System (ADS)

    Bai, Chunyan; Du, Luchun; Mei, Dongcheng

    2009-09-01

    The stochastic resonance (SR) phenomenon induced by a multiplicative periodic signal in a logistic growth model with correlated noises is studied by using the theory of signal-to-noise ratio (SNR) in the adiabatic limit. The expressions of the SNR are obtained. The effects of multiplicative noise intensity ? and additive noise intensity D, and correlated intensity ? on the SNR are discussed respectively. It is found that the existence of a maximum in the SNR is the identifying characteristic of the SR phenomena. In comparison with the SR induced by additive periodic signal, some new features are found: (1) When SNR as a function of ? for fixed ratio of ? and D, the varying of ? can induce a stochastic multi-resonance, and can induce a re-entrant transition of the peaks in SNR vs ?; (2) There exhibits a doubly critical phenomenon for SNR vs D and ?, i.e., the increasing of D (or ?) can induce the critical phenomenon for SNR with respect to ? (or D); (3) The doubly stochastic resonance effect appears when ? and D are simultaneously varying in SNR, i.e., the increment of one noise intensity can help the SR on another noise intensity come forth.

  1. Internal stochastic resonance in the coherence between spinal and cortical neuronal ensembles in the cat.

    PubMed

    Manjarrez, E; Rojas-Piloni, J G; Méndez, I; Martínez, L; Vélez, D; Vázquez, D; Flores, A

    2002-06-28

    Internal stochastic resonance is a phenomenon in which the coherence of a non-linear system is enhanced by the presence of a particular, non-zero level of noise generated by internal or external sources without a periodic input signal. The aim of this study was to demonstrate the experimental occurrence of internal stochastic resonance in the coherence between spinal and cortical neuronal ensembles. Simultaneous recordings of spinal and cortical evoked potentials were made in the somatosensory system of the anaesthetized cat. Evoked potentials were produced by input noise introduced in the tactile stimulation of the hindpaw skin. Coherence between the spinal and cortical evoked activity recorded during different levels of input noise was calculated. All animals showed distinct internal stochastic resonance like behavior. We found that the mean coherence was an inverted U-like function of the level of input noise with a mean coherence peak of 0.43. To our knowledge, this is the first documented evidence of such phenomenon in an in vivo preparation of the central nervous system. PMID:12057836

  2. Possible breakthrough: Significant improvement of signal to noise ratio by stochastic resonance

    SciTech Connect

    Kiss, L.B. [JATE University, Institute for Experimental Physics, Dom ter 9, Szeged, H-6720 (Hungary)

    1996-06-01

    The {ital simplest} {ital stochastic} {ital resonator} {ital is} {ital used}, {ital a} {ital level} {ital crossing} {ital detector} (LCD), to investigate key properties of stochastic resonance (SR). It is pointed out that successful signal processing and biological applications of SR require to work in the {ital large} {ital signal} {ital limit} (nonlinear transfer limit) which requires a completely new approach: {ital wide} {ital band} {ital input} {ital signal} and a {ital new}, {ital generalised} {ital definition} {ital of} {ital output} {ital noise}. The new way of approach is illustrated by a new arrangement. The arrangement employs a special LCD, white input noise and a special, large, subthreshold wide band signal. {ital First} {ital time} {ital in} {ital the} {ital history} {ital of} {ital SR} (for a wide band input noise), the {ital signal} {ital to} {ital noise} {ital ratio} {ital becomes} {ital much} {ital higher} {ital at} {ital the} {ital output} of a stochastic resonator than {ital at} {ital its} {ital input}. In that way, SR is proven to have a potential to improve signal transfer. Note, that the new arrangement seems to have resemblance to {ital neurone} {ital models}, therefore, it has a potential also for biological applications. {copyright} {ital 1996 American Institute of Physics.}

  3. Stochastic resonance whole body vibration reduces musculoskeletal pain: A randomized controlled trial

    PubMed Central

    Elfering, Achim; Thomann, Jan; Schade, Volker; Radlinger, Lorenz

    2011-01-01

    AIM: To examined the effects of stochastic resonance whole-body vibration training on musculoskeletal pain in young healthy individuals. METHODS: Participants were 43 undergraduate students of a Swiss University. The study was designed as a randomized controlled trial (RCT) with randomized group allocation. The RCT consisted of two groups each given 12 training sessions during four weeks with either 5 Hz- Training frequency (training condition) or 1.5 Hz Training frequency (control condition). Outcome was current musculoskeletal pain assessed in the evening on each day during the four week training period. RESULTS: Multilevel regression analysis showed musculoskeletal pain was significantly decreased in the training condition whereas there was no change in the control condition (B = -0.023, SE = 0.010, P = 0.021). Decrease in current musculoskeletal pain over four weeks was linear. CONCLUSION: Stochastic resonance whole-body vibration reduced musculoskeletal pain in young healthy individuals. Stochastic resonance vibration and not any other exercise component within training caused pain reduction. PMID:22474630

  4. Stochastic resonance effects reveal the neural mechanisms of transcranial magnetic stimulation

    PubMed Central

    Schwarzkopf, Dietrich Samuel; Silvanto, Juha; Rees, Geraint

    2011-01-01

    Transcranial magnetic stimulation (TMS) is a popular method for studying causal relationships between neural activity and behavior. However its mode of action remains controversial, and so far there is no framework to explain its wide range of facilitatory and inhibitory behavioral effects. While some theoretical accounts suggests that TMS suppresses neuronal processing, other competing accounts propose that the effects of TMS result from the addition of noise to neuronal processing. Here we exploited the stochastic resonance phenomenon to distinguish these theoretical accounts and determine how TMS affects neuronal processing. Specifically, we showed that online TMS can induce stochastic resonance in the human brain. At low intensity, TMS facilitated the detection of weak motion signals but with higher TMS intensities and stronger motion signals we found only impairment in detection. These findings suggest that TMS acts by adding noise to neuronal processing, at least in an online TMS protocol. Importantly, such stochastic resonance effects may also explain why TMS parameters that under normal circumstances impair behavior, can induce behavioral facilitations when the stimulated area is in an adapted or suppressed state. PMID:21368025

  5. Selective effects of noise by stochastic multi-resonance in coupled cells system

    NASA Astrophysics Data System (ADS)

    Zhang, Jiqian; Liu, Jianqing; Chen, Hanshuang

    2008-05-01

    By investigating a stochastic model for intracellular calcium oscillations proposed by Höfer, we have analyzed the transmission behavior of calcium signaling in a one-dimensional two-way coupled hepatocytes system. It is shown that when the first cell is subjected to the external noise, the output signal-to-noise ratio (SNR) in the cell exhibits two maxima as a function of external noise intensity, indicating the occurrence of stochastic bi-resonance (SBR). It is more important that when cells are coupled together, the resonant behavior in the 1st cell propagates along the chain with different features through the coupling effect. The cells whose locations are comparatively close to or far from the 1st cell can show SBR, while the cells located in the middle position can display stochastic multi-resonance (SMR). Furthermore, the number of cells that can show SMR increases with coupling strength enhancing. These results indicate that the cells system may make an effective choice in response to external signaling induced by noise, through the mechanism of SMR by adjusting coupling strength.

  6. Stochastic resonance in the electrically stimulated auditory nerve: predictions using a stochastic model of neural responsiveness

    NASA Astrophysics Data System (ADS)

    Xu, Yifang; Collins, Leslie

    2003-05-01

    The incorporation of low levels of noise into an electrical stimulus has been shown to improve auditory thresholds in human subjects. In this paper, thresholds for noise-modulated pulse-train stimuli are predicted by utilizing a stochastic neural-behavioral model of ensemble fiber responses to bi-phasic stimuli. A neural spike count comparison rule has been presented for both threshold and intensity discrimination under the assumption that loudness is a monotonic function of the number of neuron spikes. An alternative approach which we have pursued involves analyzing the neural response to each individual pulse within a pulse train to investigate the threshold behavior. The refractory effect is described using a Markov model for a noise-free pulse-train stimulus. A recursive method using the conditional probability is utilized to track the neural responses to each successive pulse for a noise-modulated pulse-train stimulus. After determining the stochastic properties of the auditory nerve response to each pulse within the pulse train, a logarithmic rule is hypothesized for pulse-train threshold and the predictions are shown to match psychophysical data not only for noise-free stimuli but also for noise-modulated stimuli. Results indicate that threshold decreases as noise variance increases.

  7. Types of Vestibular Disorders

    MedlinePLUS

    ... include complications from aging, autoimmune disorders, and allergies. Acoustic Neuroma Acoustic neuroma (also called a vestibular schwannoma) is a ... This nerve is also referred to as the acoustic nerve, hence the name.) As an acoustic neuroma ...

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

    SciTech Connect

    Yu, Haitao; Guo, Xinmeng; Wang, Jiang, E-mail: jiangwang@tju.edu.cn; Deng, Bin; Wei, Xile [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)

    2014-09-01

    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.

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

    PubMed

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

    2014-09-01

    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. PMID:25273205

  10. Vestibular function and cochlear implant.

    PubMed

    Robard, Laetitia; Hitier, Martin; Lebas, Catherine; Moreau, Sylvain

    2015-03-01

    Vestibular lesions are found after cochlear implantation in 23-100 % of cases. The objectives of this study were to evaluate the vestibular function before and after implantation while focusing its feasibility. This prospective study included 35 patients, mean age 49 years. Each patient enjoyed a vestibular balance before and after implantation in a median period of 5 months compared to surgery. Vestibular evaluations were performed using vestibular-evoked myogenic potentials (VEMP) and videonystagmography. Before implantation, the VEMPs were bilateral in 73 % of cases. They are modified after implantation for 13 patients, including 12 missing or reduced potentials on implanted side (p = 0.0015). Caloric tests found themselves a significant decrease in the reflectivity of the ear implanted (p < 0.0001). Vestibular symptoms were independent of changes on vestibular tests. No relation was found between the occurrence of post-operative vestibular symptoms and the results of the vestibular investigations. However, the achievement of these exams is not easy especially for children and only part of the vestibule is tested. In conclusion, the vestibular assessments help to choose the side of implantation, assess the pre-operative vestibular condition and assess and locate vestibular lesions induced. Further tests should enable a complete vestibular assessment. PMID:24737055

  11. Stochastic resonance in second-order and underdamped asymmetric bistable system

    NASA Astrophysics Data System (ADS)

    Guo, Yong-Feng; Shen, Ya-Jun; Tan, Jian-Guo

    2015-04-01

    The phenomenon of stochastic resonance (SR) in a second-order and underdamped asymmetric bistable system is investigated. The second-order asymmetric bistable system with Gauss white noise is stochastically equivalent to two-dimensional Markovian process, and the exact expression of the signal-to-noise ratio (SNR) of system response in the presence of weak periodic driving force is obtained under the adiabatic condition and the theory of two-state model intensities. The influences of the damping parameter, asymmetry constant r and the Gaussian white noises on the SNR are discussed. The present calculation results show that, the increase of static asymmetry r and damping parameter ? can restrain the SR phenomenon appears. However, the increase of signal amplitude A can enhance SR.

  12. Effect of temperature on resonant electron transport through stochastic conduction channels in superlattices

    NASA Astrophysics Data System (ADS)

    Selskii, A. O.; Koronovskii, A. A.; Hramov, A. E.; Moskalenko, O. I.; Alekseev, K. N.; Greenaway, M. T.; Wang, F.; Fromhold, T. M.; Shorokhov, A. V.; Khvastunov, N. N.; Balanov, A. G.

    2011-12-01

    We show that resonant electron transport in semiconductor superlattices with an applied electric and tilted magnetic field can, surprisingly, become more pronounced as the lattice and conduction electron temperature increases from 4.2 K to room temperature and beyond. It has previously been demonstrated that at certain critical field parameters, the semiclassical trajectories of electrons in the lowest miniband of the superlattice change abruptly from fully localized to completely unbounded. The unbounded electron orbits propagate through intricate web patterns, known as stochastic webs, in phase space, which act as conduction channels for the electrons and produce a series of resonant peaks in the electron drift velocity versus electric-field curves. Here, we show that increasing the lattice temperature strengthens these resonant peaks due to a subtle interplay between the thermal population of the conduction channels and transport along them. This enhances both the electron drift velocity and the influence of the stochastic webs on the current-voltage characteristics, which we calculate by making self-consistent solutions of the coupled electron transport and Poisson equations throughout the superlattice. These solutions reveal that increasing the temperature also transforms the collective electron dynamics by changing both the threshold voltage required for the onset of self-sustained current oscillations, produced by propagating charge domains, and the oscillation frequency.

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

    PubMed Central

    Lugo, Eduardo; Doti, Rafael; Faubert, Jocelyn

    2008-01-01

    Background Stochastic 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 stimulus only degrades the signal quality. Stochastic Resonance (SR) has been extensively studied in different physical systems. It has been extended to human sensory systems where it can be classified as unimodal, central, behavioral and recently crossmodal. However what has not been explored is the extension of this crossmodal SR in humans. For instance, if under the same auditory noise conditions the crossmodal SR persists among different sensory systems. Methodology/Principal Findings Using physiological and psychophysical techniques we demonstrate that the same auditory noise can enhance the sensitivity of tactile, visual and propioceptive system responses to weak signals. Specifically, we show that the effective auditory noise significantly increased tactile sensations of the finger, decreased luminance and contrast visual thresholds and significantly changed EMG recordings of the leg muscles during posture maintenance. Conclusions/Significance We conclude that crossmodal SR is a ubiquitous phenomenon in humans that can be interpreted within an energy and frequency model of multisensory neurons spontaneous activity. Initially the energy and frequency content of the multisensory neurons' activity (supplied by the weak signals) is not enough to be detected but when the auditory noise enters the brain, it generates a general activation among multisensory neurons of different regions, modifying their original activity. The result is an integrated activation that promotes sensitivity transitions and the signals are then perceived. A physiologically plausible model for crossmodal stochastic resonance is presented. PMID:18682745

  14. Noise sensitivity of phase-synchronization time in stochastic resonance: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Park, Kwangho; Lai, Ying-Cheng; Krishnamoorthy, Satish

    2007-04-01

    Recent numerical and heuristic arguments have revealed that the average phase-synchronization time between the input and the output associated with stochastic resonance is highly sensitive to noise variation. In particular there is evidence that this average time exhibits a cusplike behavior as the noise strength varies through the optimal value. Here we present an explicit formula for the average phase-synchronization time in terms of the phase diffusion coefficient and the average frequency difference between the input and the output signals. We also provide experimental evidence for the cusplike behavior by using a bistable microelectronic-circuit system.

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

    SciTech Connect

    Lu, Siliang; He, Qingbo, E-mail: qbhe@ustc.edu.cn; Kong, Fanrang [Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-06-15

    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.

  16. Central cross-modal stochastic resonance in human tactile blink reflex

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

    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.

  17. Novel Class of Neural Stochastic Resonance and Error-Free Information Transfer

    NASA Astrophysics Data System (ADS)

    Yasuda, Hideaki; Miyaoka, Tsuyoshi; Horiguchi, Jun; Yasuda, Akira; Hänggi, Peter; Yamamoto, Yoshiharu

    2008-03-01

    We investigate a novel class of neural stochastic resonance (SR) exhibiting error-free information transfer. Unlike conventional neural SR, where the decrease of a system’s response with too much noise is associated with an increase in the baseline firing rate, here the bell-shaped SR behavior of the input-output cross correlation emerges versus increasing input noise in spite of no significant increase of the baseline firing rate. The neuron thus acts as an error-free detector for weak signals. An integrate-and-fire model with short-term synaptic depression convincingly validates our experimental findings for SR in the human tactile blink reflex.

  18. Probability density functions of work and heat near the stochastic resonance of a colloidal particle

    NASA Astrophysics Data System (ADS)

    Imparato, Alberto; Jop, Pierre; Petrosyan, Artyom; Ciliberto, Sergio

    2008-10-01

    We study experimentally and theoretically the probability density functions of the injected and dissipated energy in a system of a colloidal particle trapped in a double-well potential periodically modulated by an external perturbation. The work done by the external force and the dissipated energy are measured close to the stochastic resonance where the injected power is maximum. We show a good agreement between the probability density functions exactly computed from a Langevin dynamics and the measured ones. The probability density function of the work done on the particle satisfies the fluctuation theorem.

  19. Experimental investigation of colored noise in stochastic resonance of a bistable beam

    NASA Astrophysics Data System (ADS)

    Tweten, Dennis J.; Mann, Brian P.

    2014-02-01

    This paper describes an experimental investigation of stochastic resonance in a bistable, composite beam excited by colored noise. Experimental results for average up-crossing period, spectral power amplification (SPA), and signal-to-noise ratio (SNR) are compared with analytical methods for underdamped systems. These analytical methods include expressions developed from Kramers, Melnikov, and two-state theory. The effect of a modal mass on the analytical expressions is explored. Finally, an alternative approach for calculating the effect of a colored noise spectrum on the SPA and SNR of underdamped systems is proposed.

  20. Stochastic resonance in an underdamped fractional oscillator with signal-modulated noise

    NASA Astrophysics Data System (ADS)

    He, Guitian; Tian, Yan; Luo, Maokang

    2014-05-01

    With increasingly deep studies into physics and technology, the behavior of fractional oscillators has become a focus of scientific research. In this paper, the fractional Langevin equation is derived from the generalized Langevin equation. Stochastic resonance (SR) in underdamped fractional oscillators driven by multiplicative noise and periodically modulated noise is extensively investigated. Using the Shapiro-Loginov formula, the moment equation and the Laplace transformation technique, the exact expression for complex susceptibility is obtained. Numerical results indicate that the influence of fractional order of the fractional oscillator, the inherent frequency of the system and the frequency of the modulated periodic signal can induce multiresonance.

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

    NASA Astrophysics Data System (ADS)

    Lu, Siliang; He, Qingbo; Kong, Fanrang

    2014-06-01

    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.

  2. Conductance with stochastic resonance in Mn{sub 12} redox network without tuning

    SciTech Connect

    Hirano, Yoshiaki [Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan); Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507 (Japan); Segawa, Yuji; Kawai, Tomoji [Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kuroda-Sowa, Takayoshi [Department of Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502 (Japan); Matsumoto, Takuya, E-mail: matsumoto-t@chem.sci.osaka-u.ac.jp [Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan)

    2014-06-09

    Artificial neuron-based information processing is one of the attractive approaches of molecular-scale electronics, which can exploit the ability of molecular system for self-assembling or self-organization. The self-organized Mn{sub 12}/DNA redox network shows nonlinear current-voltage characteristics that can be described by the Coulomb blockade network model. As a demonstration of the nonlinear network system, we have observed stochastic resonance without tuning for weak periodic input signals and thermal noise, which suggests a route to neural network composed of molecular materials.

  3. Conductance with stochastic resonance in Mn12 redox network without tuning

    NASA Astrophysics Data System (ADS)

    Hirano, Yoshiaki; Segawa, Yuji; Kuroda-Sowa, Takayoshi; Kawai, Tomoji; Matsumoto, Takuya

    2014-06-01

    Artificial neuron-based information processing is one of the attractive approaches of molecular-scale electronics, which can exploit the ability of molecular system for self-assembling or self-organization. The self-organized Mn12/DNA redox network shows nonlinear current-voltage characteristics that can be described by the Coulomb blockade network model. As a demonstration of the nonlinear network system, we have observed stochastic resonance without tuning for weak periodic input signals and thermal noise, which suggests a route to neural network composed of molecular materials.

  4. Entropic stochastic resonance of a flexible polymer chain in a confined system.

    PubMed

    Zhang, Zhen; Chen, Hanshuang; Hou, Zhonghuai

    2012-07-28

    We have studied the dynamics of a flexible polymer chain in constrained dumb-bell-shape geometry subject to a periodic force and external noise along the longitudinal direction. It is found that the system exhibits a feature of entropic stochastic resonance (ESR), i.e., the temporal coherence of the polymer motion can reach a maximum level for an optimal noise intensity. We demonstrate that the occurrence of ESR is robust to the change of chain length, while the bottleneck width should be properly chosen. A gravity force in the vertical direction is not necessary for the ESR here, however, the elastic coupling between polymer beads is crucial. PMID:22852652

  5. Stochastic resonance in the overdamped fractional oscillator subject to multiplicative dichotomous noise

    NASA Astrophysics Data System (ADS)

    He, Gui-Tian; Luo, Ren-Ze; Luo, Mao-Kang

    2013-12-01

    With the increasingly deep studies in physics and technology, the behavior of fractional oscillators have become the focus of scientific research. In this paper, the stochastic resonance (SR) mechanism of the overdamped fractional oscillator subject to multiplicative dichotomous noise is extensively investigated. Using the Shapiro-Loginov formula and the Laplace transformation technique, the exact expression for complex susceptibility is obtained. Resorting to numerical simulations, the SR phenomenon of the overdamped fractional oscillator is studied. Especially, the frequency of the external periodic force that induces multiresonance.

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

    PubMed

    Lu, Siliang; He, Qingbo; Kong, Fanrang

    2014-06-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  8. Stochastic resonance in an ensemble of bistable systems under stable distribution noises and nonhomogeneous coupling.

    PubMed

    Tang, Yang; Zou, Wei; Lu, Jianquan; Kurths, Jürgen

    2012-04-01

    In this paper, stochastic resonance of an ensemble of coupled bistable systems driven by noise having an ?-stable distribution and nonhomogeneous coupling is investigated. The ?-stable distribution considered here is characterized by four intrinsic parameters: ??(0,2] is called the stability parameter for describing the asymptotic behavior of stable densities; ??[-1,1] is a skewness parameter for measuring asymmetry; ??(0,?) is a scale parameter for measuring the width of the distribution; and ??(-?,?) is a location parameter for representing the mean value. It is demonstrated that the resonant behavior is optimized by an intermediate value of the diversity in coupling strengths. We show that the stability parameter ? and the scale parameter ? can be well selected to generate resonant effects in response to external signals. In addition, the interplay between the skewness parameter ? and the location parameter ? on the resonance effects is also studied. We further show that the asymmetry of a Lévy ?-stable distribution resulting from the skewness parameter ? and the location parameter ? can enhance the resonance effects. Both theoretical analysis and simulation are presented to verify the results of this paper. PMID:22680556

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

    NASA Technical Reports Server (NTRS)

    Wisdom, J.

    1980-01-01

    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.

  10. Parameter dependence of stochastic resonance in the FitzHugh-Nagumo neuron model driven by trichotomous noise

    NASA Astrophysics Data System (ADS)

    Zhang, Huiqing; Yang, Tingting; Xu, Yong; Xu, Wei

    2015-05-01

    We investigate the stochastic resonance in a FitzHugh-Nagumo neuron model driven by trichotomous noise and periodic signal, focusing on the dependence of properties of stochastic resonance (SR) on system parameters. The stochastic resonance is shown through several different measures: system response, power spectrum and signal-to-noise ratio. Firstly, it is found that whether the neuron can fire regularly depends on the cooperative effect of the signal frequency and the signal amplitude for the deterministic FHN neuron. When the forcing amplitude alone is insufficient to cause the neuron firing, the neuron can fire with the addition of trichotomous noise. Secondly, we show that power spectrum is maximized for an optimal value of the noise correlation time, which is the signature of SR. Finally, from studying SNR, the specific system parameters are found to optimize the SR phenomenon.

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

    PubMed

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

    2014-05-01

    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

  12. An adaptive single-well stochastic resonance algorithm applied to trace analysis of clenbuterol in human urine.

    PubMed

    Wang, Wei; Xiang, Suyun; Xie, Shaofei; Xiang, Bingren

    2012-01-01

    Based on the theory of stochastic resonance, an adaptive single-well stochastic resonance (ASSR) coupled with genetic algorithm was developed to enhance the signal-to-noise ratio of weak chromatographic signals. In conventional stochastic resonance algorithm, there are two or more parameters needed to be optimized and the proper parameters values were obtained by a universal searching within a given range. In the developed ASSR, the optimization of system parameter was simplified and automatic implemented. The ASSR was applied to the trace analysis of clenbuterol in human urine and it helped to significantly improve the limit of detection and limit of quantification of clenbuterol. Good linearity, precision and accuracy of the proposed method ensure that it could be an effective tool for trace analysis and the improvement of detective sensibility of current detectors. PMID:22337140

  13. Nuclear quadrupole resonance lineshape analysis for different motional models: stochastic Liouville approach.

    PubMed

    Kruk, D; Earle, K A; Mielczarek, A; Kubica, A; Milewska, A; Moscicki, J

    2011-12-14

    A general theory of lineshapes in nuclear quadrupole resonance (NQR), based on the stochastic Liouville equation, is presented. The description is valid for arbitrary motional conditions (particularly beyond the valid range of perturbation approaches) and interaction strengths. It can be applied to the computation of NQR spectra for any spin quantum number and for any applied magnetic field. The treatment presented here is an adaptation of the "Swedish slow motion theory," [T. Nilsson and J. Kowalewski, J. Magn. Reson. 146, 345 (2000)] originally formulated for paramagnetic systems, to NQR spectral analysis. The description is formulated for simple (Brownian) diffusion, free diffusion, and jump diffusion models. The two latter models account for molecular cooperativity effects in dense systems (such as liquids of high viscosity or molecular glasses). The sensitivity of NQR slow motion spectra to the mechanism of the motional processes modulating the nuclear quadrupole interaction is discussed. PMID:22168707

  14. Measurement of the direct particle transport through stochastic media using neutron resonance transmission analysis

    NASA Astrophysics Data System (ADS)

    Becker, Bjorn; Kopecky, Stefan; Harada, Hideo; Schillebeeckx, Peter

    2014-04-01

    A measurement of the uncollided neutron flux passing through a sample containing a stochastic mixture of tungsten and sulfur grains has been performed using neutron resonance transmission analysis in the 3-200eV energy region. The impact of the heterogeneous characteristic of the sample is shown, based on a comparison of the measurement with a calculated transmission spectrum of a homogeneous sample, which was verified by a measurement with a homogeneous metallic disc. By using a single strong resonance of tungsten, the particle self-shielding factor between 0.2-0.9 was directly measured. The experimental data have been compared with model calculations using the Markovian Levermore-Pomraning model. The measured transmission has been used to determine the effective characteristic chord length and volume fraction of the tungsten grains within the sample.

  15. Stochastic resonance in a groundwater-dependent plant ecosystem with fluctuations and time delay

    NASA Astrophysics Data System (ADS)

    Jia, Zheng-Lin; Yang, Chun-Yan; Li, Chun; Mei, Dong-Cheng

    2014-03-01

    We numerically investigate the stochastic resonance (SR) pheno menon in a groundwater-dependent plant ecosystem under the combined influence of environmental fluctuations, seasonal rainfall oscillation, and time delay. The effects of time delay and intrinsic and extrinsic fluctuations on the output signal-to-noise ratio (SNR) of the system are analyzed. The results indicate that the SNR exhibits a maximum as a function of the intensities of the intrinsic and extrinsic noises, identifying the occurrence of the SR effect. An increase of the delay time always suppresses the SR effect, while an increase of correlation strength between noises may suppress or enhance it. The SNR also shows a resonant behavior as a function of the correlation strength between noises, and it can be weakened by the time delay.

  16. An investigation of the plausibility of stochastic resonance in tubulin dimers.

    PubMed

    Saha, Aditya A; Craddock, Travis J A; Tuszynski, Jack A

    2012-02-01

    This paper considers the possibility of stochastic resonance (SR) in tubulin dimers. A formula for the signal-to-noise ratio (SNR) of tubulin as a function of temperature is derived. The effective potential experienced by a delocalized electron in such a dimer is postulated to be a symmetric bimodal well. Inter-well and intra-well motions are described by Kramers rate theory and the Langevin formalism respectively. The frequency-dependent expression for the SNR shows that the response of the electron-tubulin dimer system is enhanced by ambient dipolar oscillations in specific frequency regimes. This is a characteristic of SR. Biophysical implications of this property such as the relevance to 8.085 MHz microtubule resonance and the clocking mechanism are detailed. PMID:22001523

  17. Stochastic resonance in feedforward-loop neuronal network motifs in astrocyte field.

    PubMed

    Liu, Ying; Li, Chunguang

    2013-10-21

    Elucidating the underlying dynamical properties of neuronal network motifs, statistically significant patterns of interconnections, is essential to understand the dynamics of the whole networks. Besides, the brain is intrinsically noisy. Various noise-induced dynamical behaviors, in particular, the stochastic resonance (SR), have been found in both neuronal systems and neuronal network motifs. However, the effect of astrocytes, active partners in neuronal signal processing, has not yet received much attention. In this paper, we study the effect of astrocytes on the stochastic behaviors of the typical triple-neuron feedforward-loop (FFL) neuronal network motifs. The neurons are described by the Hodgkin-Huxley model, while the astrocytes are modeled by extending the Li-Rinzel model to a two-dimensional field with the effect of diffusion. The mutual neuron-astrocyte interactions are established correspondingly. Simulation results indicate that the stochastic behaviors of the FFL motifs show bell-shaped dependence on the intensities of both noise and astrocyte-neuron coupling. Moreover, in the presence of astrocytes, the performance of the FFL motifs on weak signal transmission in both noisy and noise-free environments can be significantly improved. From this point of view, the astrocytes can be regarded as a possible internal source of "noise", which assist the neurons in signal processing. PMID:23871712

  18. Preservation of auditory and vestibular function after surgical removal of bilateral vestibular schwannomas in a patient with neurofibromatosis type 2

    NASA Technical Reports Server (NTRS)

    Black, F. O.; Brackmann, D. E.; Hitselberger, W. E.; Purdy, J.

    1995-01-01

    The outcome of acoustic neuroma (vestibular schwannoma) surgery continues to improve rapidly. Advances can be attributed to several fields, but the most important contributions have arisen from the identification of the genes responsible for the dominant inheritance of neurofibromatosis types 1 (NF1) and 2 (NF2) and the development of magnetic resonance imaging with gadolinium enhancement for the early anatomic confirmation of the pathognomonic, bilateral vestibular schwannomas in NF2. These advances enable early diagnosis and treatment when the tumors are small in virtually all subjects at risk for NF2. The authors suggest that advising young NF2 patients to wait until complications develop, especially hearing loss, before diagnosing and operating for bilateral eighth nerve schwannomas may not always be in the best interest of the patient. To the authors' knowledge, this is the first reported case of preservation of both auditory and vestibular function in a patient after bilateral vestibular schwannoma excision.

  19. Recovery from vestibular ototoxicity

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  20. Vestibular-Ocular Reflex

    NSDL National Science Digital Library

    Marlene Y. MacLeish, Ed.D.

    2013-01-30

    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.

  1. The rate matching effect: A hidden property of aperiodic stochastic resonance

    NASA Astrophysics Data System (ADS)

    Lukovi?, Mirko; Ignaccolo, Massimiliano; Fronzoni, Leone; Grigolini, Paolo

    2008-04-01

    We study a system S generating Poisson events, and a corresponding dichotomous signal as well, perturbed by a system P, also generating Poisson events and a corresponding dichotomous signal. The rates of events productions for system and perturbation are g and g, respectively. We call S events the events produced by the system S and P events those produced by the perturbation P. We show that this simple model reproduces the essence of recent experimental and theoretical results on aperiodic stochastic resonance. More remarkably, this simplified version of aperiodic stochastic resonance allows us to discover a property that has been overlooked by the earlier research work. The rate matching condition g=g is the border between two distinctly different conditions: For gg they become repellers of the S events. The transition from the former to the latter condition is very marked and takes place in a short region of either g or g, depending on which is the parameter changed, thereby resulting in a discontinuous transition.

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

    PubMed Central

    Chakravarthy, V. Srinivasa

    2013-01-01

    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

  3. Multiple coherence resonance induced by time-periodic coupling in stochastic Hodgkin-Huxley neuronal networks

    NASA Astrophysics Data System (ADS)

    Lin, Xiu; Gong, Yubing; Wang, Li

    2011-12-01

    In this paper, we study the effect of time-periodic coupling strength (TPCS) on the spiking coherence of Newman-Watts small-world networks of stochastic Hodgkin-Huxley (HH) neurons and investigate the relations between the coupling strength and channel noise when coherence resonance (CR) occurs. It is found that, when the amplitude of TPCS is varied, the spiking induced by channel noise can exhibit CR and coherence bi-resonance (CBR), and the CR moves to a smaller patch area (bigger channel noise) when the amplitude increases; when the frequency of TPCS is varied, the intrinsic spiking can exhibit CBR and multiple CR, and the CR always occurs when the frequency is equal to or multiple of the spiking period, manifesting as the locking between the frequencies of the intrinsic spiking and the coupling strength. These results show that TPCS can greatly enhance and optimize the intrinsic spiking coherence, and favors the spiking with bigger channel noise to exhibit CR. This implies that, compared to constant coupling strength, TPCS may play a more efficient role for improving the time precision of the information processing in stochastic neuronal networks.

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

    NASA Astrophysics Data System (ADS)

    Epstein, S.; Paul, M. R.

    2013-10-01

    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.

  5. Weak-periodic stochastic resonance in a parallel array of static nonlinearities.

    PubMed

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

    2013-01-01

    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

  6. Do basal Ganglia amplify willed action by stochastic resonance? A model.

    PubMed

    Chakravarthy, V Srinivasa

    2013-01-01

    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

  7. Entropic stochastic resonance enables trapping under periodic confinement: A Brownian-dynamics study

    NASA Astrophysics Data System (ADS)

    Shi, Nan; Ugaz, Victor M.

    2014-01-01

    Entropically mediated phenomena are of emerging interest as a driving force for microscale and nanoscale transport, but their underlying stochastic nature makes them challenging to rationally manipulate and control. Stochastic resonance offers an intriguing avenue to overcome these difficulties by establishing a clear connection between the system response (the output) and an externally imposed driving force (the input). Previous studies have generally adopted a signal-processing viewpoint to classify the output in terms of a signal-to-noise ratio, but this link does not convey information that is immediately useful to infer parameters relevant to transport. Here we address this issue by applying Brownian-dynamics simulations to elucidate the residence time distribution encountered by a particle as it travels through a channel incorporating periodic constrictions. A sinusoidal longitudinal driving force is applied with a superimposed continuous orthogonal component, making it possible to identify frequency and amplitude conditions where temporal coherence with the particle's motion can be achieved. This resonant state reflects a synergistic combination of geometry and driving force that can be exploited to confine species at discrete locations, offering possibilities for directed manipulation.

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

    NASA Astrophysics Data System (ADS)

    McDonnell, Mark D.; Gao, Xiao

    2014-12-01

    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.

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

    PubMed Central

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

    2013-01-01

    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

  10. Entropic stochastic resonance enables trapping under periodic confinement: a Brownian-dynamics study.

    PubMed

    Shi, Nan; Ugaz, Victor M

    2014-01-01

    Entropically mediated phenomena are of emerging interest as a driving force for microscale and nanoscale transport, but their underlying stochastic nature makes them challenging to rationally manipulate and control. Stochastic resonance offers an intriguing avenue to overcome these difficulties by establishing a clear connection between the system response (the output) and an externally imposed driving force (the input). Previous studies have generally adopted a signal-processing viewpoint to classify the output in terms of a signal-to-noise ratio, but this link does not convey information that is immediately useful to infer parameters relevant to transport. Here we address this issue by applying Brownian-dynamics simulations to elucidate the residence time distribution encountered by a particle as it travels through a channel incorporating periodic constrictions. A sinusoidal longitudinal driving force is applied with a superimposed continuous orthogonal component, making it possible to identify frequency and amplitude conditions where temporal coherence with the particle's motion can be achieved. This resonant state reflects a synergistic combination of geometry and driving force that can be exploited to confine species at discrete locations, offering possibilities for directed manipulation. PMID:24580203

  11. Multiple coherence resonance induced by time-periodic coupling in stochastic Hodgkin-Huxley neuronal networks.

    PubMed

    Lin, Xiu; Gong, Yubing; Wang, Li

    2011-12-01

    In this paper, we study the effect of time-periodic coupling strength (TPCS) on the spiking coherence of Newman-Watts small-world networks of stochastic Hodgkin-Huxley (HH) neurons and investigate the relations between the coupling strength and channel noise when coherence resonance (CR) occurs. It is found that, when the amplitude of TPCS is varied, the spiking induced by channel noise can exhibit CR and coherence bi-resonance (CBR), and the CR moves to a smaller patch area (bigger channel noise) when the amplitude increases; when the frequency of TPCS is varied, the intrinsic spiking can exhibit CBR and multiple CR, and the CR always occurs when the frequency is equal to or multiple of the spiking period, manifesting as the locking between the frequencies of the intrinsic spiking and the coupling strength. These results show that TPCS can greatly enhance and optimize the intrinsic spiking coherence, and favors the spiking with bigger channel noise to exhibit CR. This implies that, compared to constant coupling strength, TPCS may play a more efficient role for improving the time precision of the information processing in stochastic neuronal networks. PMID:22225346

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

    PubMed Central

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

    2011-01-01

    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

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

    Microsoft Academic Search

    Eran Segev; Baleegh Abdo; Oleg Shtempluck; Eyal Buks

    2008-01-01

    We study thermal instability in NbN superconducting stripline resonators. The system exhibits extreme nonlinearity near a bifurcation, which separates a monostable zone and an astable one. The lifetime of the metastable state, which is locally stable in the monostable zone, is measured near the bifurcation and the results are compared with a theory. Near bifurcation, where the lifetime becomes relatively

  14. Compton harmonic resonances, stochastic instabilities, quasilinear diffusion, and collisionless damping with ultra-high intensity laser waves

    SciTech Connect

    Rax, J.M.

    1992-04-01

    The dynamics of electrons in two-dimensional, linearly or circularly polarized, ultra-high intensity (above 10{sup 18}W/cm{sup 2}) laser waves, is investigated. The Compton harmonic resonances are identified as the source of various stochastic instabilities. Both Arnold diffusion and resonance overlap are considered. The quasilinear kinetic equation, describing the evolution of the electron distribution function, is derived, and the associated collisionless damping coefficient is calculated. The implications of these new processes are considered and discussed.

  15. Long-Time Dynamic Response and Stochastic Resonance of Subdiffusive Overdamped Bistable Fractional Fokker-Planck Systems

    NASA Astrophysics Data System (ADS)

    Kang, Yan-Mei; Jiang, Yao-Lin

    2008-10-01

    To explore the influence of anomalous diffusion on stochastic resonance (SR) more deeply and effectively, the method of moments is extended to subdiffusive overdamped bistable fractional Fokker-Planck systems for calculating the long-time linear dynamic response. It is found that the method of moments attains high accuracy with the truncation order N = 10, and in normal diffusion such obtained spectral amplification factor (SAF) of the first-order harmonic is also confirmed by stochastic simulation. Observing the SAF of the odd-order harmonics we find some interesting results, i.e. for smaller driving frequency the decrease of sub diffusion exponent inhibits the stochastic resonance (SR), while for larger driving frequency the decrease of sub diffusion exponent enhances the second SR peak, but the first one vanishes and a double SR is induced in the third-order harmonic at the same time. These observations suggest that the anomalous diffusion has important influence on the bistable dynamics.

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

    Microsoft Academic Search

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

    2007-01-01

    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

  17. Variance and kurtosis-based characterization of resonances in stochastic transmission lines: local versus global random geometries

    Microsoft Academic Search

    Ousmane Oumar SY; Martijn C. van BEURDEN; Bastiaan L. MICHIELSEN; AG Tijhuis

    2009-01-01

    A stochastic method is proposed to characterize electromagnetic couplings involving geometrically per- turbed transmission lines. A combined exploitation of suitably defined statistical tools is presented to appre- ciate the intensity of the dispersion of response variables both physically via the variance, and statistically through the kurtosis or fourth-order moment. The usefulness of this method to analyze resonances is illus- trated

  18. RESONANCE OF COEFFICIENT OF VARIATION INDUCED BY REBOUND CURRENTS FOR STOCHASTIC INHIBITORY INPUTS Ramana Dodla and Charles J. Wilson

    E-print Network

    Dodla, Ramana

    RESONANCE OF COEFFICIENT OF VARIATION INDUCED BY REBOUND CURRENTS FOR STOCHASTIC INHIBITORY INPUTS rebound current (parameterized by its maximal conductance, GT) caused by the brief inputs can induce the rebound is strong, the CV exhibits an unexpected and prominent local maximum at a preferred input

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  20. Fisher Information as a Metric of Locally Optimal Processing and Stochastic Resonance

    PubMed Central

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

    2012-01-01

    The origins of Fisher information are in its use as a performance measure for parametric estimation. We augment this and show that the Fisher information can characterize the performance in several other significant signal processing operations. For processing of a weak signal in additive white noise, we demonstrate that the Fisher information determines (i) the maximum output signal-to-noise ratio for a periodic signal; (ii) the optimum asymptotic efficacy for signal detection; (iii) the best cross-correlation coefficient for signal transmission; and (iv) the minimum mean square error of an unbiased estimator. This unifying picture, via inequalities on the Fisher information, is used to establish conditions where improvement by noise through stochastic resonance is feasible or not. PMID:22493686

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

    PubMed Central

    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

    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

  2. Entropic noise induced stability and double entropic stochastic resonance induced by correlated noises

    NASA Astrophysics Data System (ADS)

    Zeng, Chun-Hua; Wang, Hua; Wang, Hui-Tao

    2011-05-01

    For the activated dynamics of a Brownian particle moving in a confined system with the presence of entropic barriers, this paper investigates a periodic driving and correlations between two noises. Within the two-state approximation, the explicit expressions of the mean first passage time (MFPT) and the spectral power amplification (SPA) are obtained, respectively. Based on the numerical computations, it is found that: (i) The MFPT as a function of the noise intensity exhibits a maximum with the positive correlations between two noises (? > 0), this maximum for MFPT shows the characteristic of the entropic noise induced stability (ENIS) effect. The intensity ? of correlations between two noises can enhance the ENIS effect. (ii) The SPA as a function of the noise intensity exhibits a double-peak by tuning the noise correlation intensity ?, i.e., the existence of a double-peak behaviour is the identifying characteristic of the double entropic stochastic resonance phenomenon.

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

    PubMed

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

    2008-04-28

    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

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

    NASA Astrophysics Data System (ADS)

    Guo, Feng; Li, Heng; Liu, Jing

    2014-09-01

    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.

  5. Stochastic Resonance in a Bacterium Growth System with Time Delay and Colored Noise

    NASA Astrophysics Data System (ADS)

    Li, Shenghong; Wu, Jiancheng

    2015-04-01

    The phenomenon of stochastic resonance in a bacterium growth system that is with two different kinds of time delays and is driven by colored noises is investigated. Based on the extended unified colored noise theory and the method of the probability density approximation, the Fokker-Planck equation and the stationary probability density function are derived. Then via the theory of adiabatic limit, the analytical expression of the signal-to-noise ratio (SNR) is obtained. The different effects of the time delays existed in the nonlinear system and the noise correlation times on the stationary probability density and the signal-to-noise rate are discussed respectively. Finally, numerical simulations are offered and are consistent with approximate analytical results.

  6. Logical stochastic resonance with correlated internal and external noises in a synthetic biological logic block

    NASA Astrophysics Data System (ADS)

    Dari, Anna; Kia, Behnam; Bulsara, Adi R.; Ditto, William L.

    2011-12-01

    Following the advent of synthetic biology, several gene networks have been engineered to emulate digital devices, with the ability to program cells for different applications. In this work, we adapt the concept of logical stochastic resonance to a synthetic gene network derived from a bacteriophage ?. The intriguing results of this study show that it is possible to build a biological logic block that can emulate or switch from the AND to the OR gate functionalities through externally tuning the system parameters. Moreover, this behavior and the robustness of the logic gate are underpinned by the presence of an optimal amount of random fluctuations. We extend our earlier work in this field, by taking into account the effects of correlated external (additive) and internal (multiplicative or state-dependent) noise. Results obtained through analytical calculations as well as numerical simulations are presented.

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

    PubMed

    Yonekura, Shogo; Kuniyoshi, Yasuo; Kawaguchi, Yoichiro

    2012-07-01

    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

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

    PubMed

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

    2014-01-01

    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

  9. Improved detection of magnetic signals by a MEMS sensor using stochastic resonance.

    PubMed

    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

    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

  10. Stochastic resonance induced by exogenous noise in a model of a neuronal network.

    PubMed

    Paffi, Alessandra; Apollonio, Francesca; d'Inzeo, Guglielmo; Liberti, Micaela

    2013-01-01

    This study investigates the possibility of using exogenous noise to restore the processing performances of neuronal systems where the endogenous noise is reduced due to the ageing or to degenerative diseases. This idea is based on the assumption, supported by theoretical studies, that the endogenous noise has a positive role in neuronal signal detection and that its reduction impairs the system function. Results, obtained on a two-layers feedforward network, show the onset of the Stochastic Resonance (SR) behavior, as long as the exogenous noise is properly tailored and filtered. The amount of noise to be furnished from the outside to optimize the system performance depends on the residual level of endogenous noise, indicating that both kinds of noise cooperate to the signal detection. These results support potentially new bioengineering applications where exogenous noise is furnished to enhance signal detectability. PMID:23654221

  11. Improvement of tactile sensitivity by stochastic resonance effect--applications to surgical grasping forceps.

    PubMed

    Sueda, Yamato; Hattori, Minoru; Sawada, Hiroyuki; Egi, Hiroyuki; Ohdan, Hideki; Ueda, Jun; Tsuji, Toshio; Kurita, Yuichi

    2013-01-01

    This paper reports experimental results on a surgical grasping forceps with a vibration actuator that enhances a tactile perception ability. A short-time exposure of tactile receptors to sub-sensory white-noise vibration is known to improve perception ability. This phenomenon, called stochastic resonance (SR) in the somatosensory system, is expected to enhance the sense of touch when the weak vibration is applied to a fingertip, and thereby improve associated motor skills. A lead zirconate titanate (PZT) actuator was attached on the grip of surgical grasping forceps. A passive sensory test has been conducted for healthy subjects to confirm the efficacy of the device. Statistical significance has been observed when appropriate noise is applied. To investigate the effect of the noise intensity, a summing network of FitzHugh-Nagumo model neurons was built. The simulation results showed that a network with relatively large units can improve the detection capability of the input signal. PMID:24110759

  12. Periodically driven underdamped periodic and washboard potential systems: dynamical states and stochastic resonance.

    PubMed

    Reenbohn, W L; Pohlong, S S; Mahato, Mangal C

    2012-03-01

    We have studied the motion of an underdamped Brownian particle in (i) a bistable periodic potential and (ii) washboard potentials subjected to a sinusoidal external field. The particles are shown to be effectively in two dynamical states of their trajectories with distinct amplitudes and phase relationship with the external drive. These dynamical states are stable with fixed energies at low temperatures, but transitions between them take place as the temperature is increased. The average input energy loss to the environment per period of the drive shows a stochastic resonance (SR) peak as a function of temperature for the underdamped system potentials studied. The occurrence of SR in these systems is explained using the statistics of transitions between the two dynamical states. PMID:22587075

  13. Logical stochastic resonance with correlated internal and external noises in a synthetic biological logic block.

    PubMed

    Dari, Anna; Kia, Behnam; Bulsara, Adi R; Ditto, William L

    2011-12-01

    Following the advent of synthetic biology, several gene networks have been engineered to emulate digital devices, with the ability to program cells for different applications. In this work, we adapt the concept of logical stochastic resonance to a synthetic gene network derived from a bacteriophage ?. The intriguing results of this study show that it is possible to build a biological logic block that can emulate or switch from the AND to the OR gate functionalities through externally tuning the system parameters. Moreover, this behavior and the robustness of the logic gate are underpinned by the presence of an optimal amount of random fluctuations. We extend our earlier work in this field, by taking into account the effects of correlated external (additive) and internal (multiplicative or state-dependent) noise. Results obtained through analytical calculations as well as numerical simulations are presented. PMID:22225395

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

    PubMed Central

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

    2008-01-01

    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

  15. Fisher information as a metric of locally optimal processing and stochastic resonance.

    PubMed

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

    2012-01-01

    The origins of Fisher information are in its use as a performance measure for parametric estimation. We augment this and show that the Fisher information can characterize the performance in several other significant signal processing operations. For processing of a weak signal in additive white noise, we demonstrate that the Fisher information determines (i) the maximum output signal-to-noise ratio for a periodic signal; (ii) the optimum asymptotic efficacy for signal detection; (iii) the best cross-correlation coefficient for signal transmission; and (iv) the minimum mean square error of an unbiased estimator. This unifying picture, via inequalities on the Fisher information, is used to establish conditions where improvement by noise through stochastic resonance is feasible or not. PMID:22493686

  16. Note: signal amplification and filtering with a tristable stochastic resonance cantilever.

    PubMed

    Lu, Siliang; He, Qingbo; Zhang, Haibin; Zhang, Shangbin; Kong, Fanrang

    2013-02-01

    This Note reports a tristable cantilever that exploits stochastic resonance (SR) phenomenon for a study of signal amplification and filtering. The tristable device system combines the benefits of bistable system (wide interwell spacing) and monostable system (smooth motion in potential). The prototype tristable cantilever exhibits 42 times root-mean-square amplitude, 35.86 dB power gain, advance of 15 dB signal-to-noise ratio, and twice fidelity at around 7.6 Hz as compared to the input signal. In a wide operating bandwidth [5.5 Hz, 8.2 Hz], the tristable SR cantilever outperforms the traditional monostable cantilever and bistable SR cantilever in these characteristics. PMID:23464272

  17. Stochastic resonance in a tumor-immune system subject to bounded noises and time delay

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Mei, Dong-Cheng

    2014-12-01

    Immunotherapy is one of the most recent approaches in cancer therapy. A mathematical model of tumor-immune interaction, subject to a periodic immunotherapy treatment (imitated by a periodic signal), correlative and bounded stochastic fluctuations and time delays, is investigated by numerical simulations for its signal power amplification (SPA). Within the tailored parameter regime, the synchronous response of tumor growth to the immunotherapy, stochastic resonance (SR), versus both the noises and delays is obtained. The details are as follows (i) the peak values of SPA versus the noise intensity (A) in the proliferation term of tumor cells decrease as the frequency of periodic signal increases, i.e. an increase of the frequency restrains the SR; (ii) an increase of the amplitude of periodic signal restrains the SR versus A, but boosts up the SR versus the noise intensity B in the immune term; (iii) there is an optimum cross-correlated degree between the two bounded noises, at which the system exhibits the strongest SR versus the delay time ??(the reaction time of tumor cell population to their surrounding environment constraints); (iv) upon increasing the delay time ??, double SR versus the delay time ?? (the time taken by both the tumor antigen identification and tumor-stimulated proliferation of effectors) emerges. These results may be helpful for an immunotherapy treatment for the sufferer.

  18. Enhancement of positron emission tomography-computed tomography image quality using the principle of stochastic resonance

    PubMed Central

    Pandey, Anil Kumar; Sharma, Sanjay Kumar; Sharma, Punit; Singh, Harmandeep; Patel, Chetan; Sarkar, Kaushik; Kumar, Rakesh; Bal, Chandra Sekhar

    2014-01-01

    Purpose: Acquisition of higher counts improves visual perception of positron emission tomography-computed tomography (PET-CT) image. Larger radiopharmaceutical doses (implies more radiation dose) are administered to acquire this count in a short time period. However, diagnostic information does not increase after a certain threshold of counts. This study was conducted to develop a post processing method based on principle of “stochastic resonance” to improve visual perception of the PET-CT image having a required threshold counts. Materials and Methods: PET-CT images (JPEG file format) with low, medium, and high counts in the image were included in this study. The image was corrupted with the addition of Poisson noise. The amplitude of the Poisson noise was adjusted by dividing each pixel by a constant 1, 2, 4, 8, 16, and 32. The best amplitude of the noise that gave best images quality was selected based on high value of entropy of the output image, high value of structural similarity index and feature similarity index. Visual perception of the image was evaluated by two nuclear medicine physicians. Results: The variation in structural and feature similarity of the image was not appreciable visually, but statistically images deteriorated as the noise amplitude increases although maintaining structural (above 70%) and feature (above 80%) similarity of input images in all cases. We obtained the best image quality at noise amplitude “4” in which 88% structural and 95% feature similarity of the input images was retained. Conclusion: This method of stochastic resonance can be used to improve the visual perception of the PET-CT image. This can indirectly lead to reduction of radiation dose. PMID:25400362

  19. Improving Early Adaptation Following Long Duration Spaceflight by Enhancing Vestibular Information

    NASA Technical Reports Server (NTRS)

    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

    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.

  20. Stochastic resonance for a metapopulation system driven by multiplicative and additive colored noises

    NASA Astrophysics Data System (ADS)

    Wang, Kang-Kang; Liu, Xian-Bin

    2014-01-01

    We investigate the stochastic resonance (SR) phenomenon induced by the periodic signal in a metapopulation system with colored noises. The analytical expression of signal-to-noise is derived in the adiabatic limit. By numerical calculation, the effects of the addictive noise intensity, the multiplicative noise intensity and two noise self-correlation times on SNR are respectively discussed. It shows that: (i) in the case that the addictive noise intensity M takes a small value, a SR phenomenon for the curve of SNR appears; however, when M takes a large value, SNR turns into a monotonic function on the multiplicative noise intensity Q. (ii) The resonance peaks in the plots of the multiplicative noise intensity Q versus its self-correlation time ?1 and the addictive noise intensity M versus its self-correlation time ?2 translate in parallel. Meanwhile, a parallel translation also appears in the plots of ?1 versus Q and ?2 versus M. (iii) The interactive effects between self-correlation times ?1 and ?2 are opposite.

  1. Conflicting visual-vestibular stimulation and vestibular nucleus activity in alert monkeys

    Microsoft Academic Search

    W. Waespe; V. Henn

    1978-01-01

    In alert Rhesus monkeys (Macaca mulatta) neuronal activity of vestibular nuclei was recorded during pure vestibular and conflicting visual-vestibular stimulation. Pure vestibular stimulation consisted of rotating the monkey about the vertical axis in complete darkness. During conflicting visual-vestibular stimulation the monkeys were rotated in the light within a vertically striped cylinder mechanically coupled to the turntable. The conflict is that

  2. Vestibular pathways involved in cognition.

    PubMed

    Hitier, Martin; Besnard, Stephane; Smith, Paul F

    2014-01-01

    Recent discoveries have emphasized the role of the vestibular system in cognitive processes such as memory, spatial navigation and bodily self-consciousness. A precise understanding of the vestibular pathways involved is essential to understand the consequences of vestibular diseases for cognition, as well as develop therapeutic strategies to facilitate recovery. The knowledge of the "vestibular cortical projection areas", defined as the cortical areas activated by vestibular stimulation, has dramatically increased over the last several years from both anatomical and functional points of view. Four major pathways have been hypothesized to transmit vestibular information to the vestibular cortex: (1) the vestibulo-thalamo-cortical pathway, which probably transmits spatial information about the environment via the parietal, entorhinal and perirhinal cortices to the hippocampus and is associated with spatial representation and self-versus object motion distinctions; (2) the pathway from the dorsal tegmental nucleus via the lateral mammillary nucleus, the anterodorsal nucleus of the thalamus to the entorhinal cortex, which transmits information for estimations of head direction; (3) the pathway via the nucleus reticularis pontis oralis, the supramammillary nucleus and the medial septum to the hippocampus, which transmits information supporting hippocampal theta rhythm and memory; and (4) a possible pathway via the cerebellum, and the ventral lateral nucleus of the thalamus (perhaps to the parietal cortex), which transmits information for spatial learning. Finally a new pathway is hypothesized via the basal ganglia, potentially involved in spatial learning and spatial memory. From these pathways, progressively emerges the anatomical network of vestibular cognition. PMID:25100954

  3. Fisioterapia Aquática para Reabilitação Vestibular

    Microsoft Academic Search

    Yeda P. L. Gabilan; Mônica R. Perracini; Mario S. L. Munhoz; Fernando F. Ganança; Vila Clementino

    2006-01-01

    Objective: Prepare a protocol of vestibular rehabilitation in therapeutic pools. Method: a protocol of exercises for patients with vestibular affections was created, based on principles and physical laws of the water, physiological effects of the immersed body as well exercises of Halliwick and Bad Ragaz for aquatic physiotherapy as well as protocols of Cawthorne & Cooksey protocol, Ganança et al,

  4. Peripheral Vestibular Responses to Sound

    Microsoft Academic Search

    Ian S. Curthoys

    2006-01-01

    As well as activating the cochlea, sound also activates some vestibular receptors and afferents. That is true for both air- and bone-conducted sound and this review briefly summarizes the neural evidence for vestibular activation by sound in mammals and considers the implications of this result. These neural results have been rapidly translated into clinical use and underpin a new clinical

  5. Vestibular blueprint in early vertebrates

    PubMed Central

    Straka, Hans; Baker, Robert

    2013-01-01

    Central vestibular neurons form identifiable subgroups within the boundaries of classically outlined octavolateral nuclei in primitive vertebrates that are distinct from those processing lateral line, electrosensory, and auditory signals. Each vestibular subgroup exhibits a particular morpho-physiological property that receives origin-specific sensory inputs from semicircular canal and otolith organs. Behaviorally characterized phenotypes send discrete axonal projections to extraocular, spinal, and cerebellar targets including other ipsi- and contralateral vestibular nuclei. The anatomical locations of vestibuloocular and vestibulospinal neurons correlate with genetically defined hindbrain compartments that are well conserved throughout vertebrate evolution though some variability exists in fossil and extant vertebrate species. The different vestibular subgroups exhibit a robust sensorimotor signal processing complemented with a high degree of vestibular and visual adaptive plasticity. PMID:24312016

  6. Stochastic resonance in noise-induced transitions between self-oscillations and equilibria in spin-valve nanomagnets

    NASA Astrophysics Data System (ADS)

    D'Aquino, M.; Serpico, C.; Bonin, R.; Bertotti, G.; Mayergoyz, I. D.

    2011-12-01

    The thermally induced synchronization between magnetization transitions and “weak” ac excitations is studied for spin-transfer oscillators. A theoretical approach, based on the separation of time scales, is developed to investigate this physical phenomenon. By applying the appropriate averaging technique to the Fokker-Planck equation associated with the stochastic magnetization dynamics, a stochastic differential equation for the “slow” (energy) variable is derived. This equation is used to analyze intrawell thermal transitions between magnetization equilibria and self-oscillations. It is demonstrated that the thermally induced synchronization between magnetization transitions and ac excitation can be viewed as a stochastic resonance effect. It is shown that this effect occurs in spin-transfer nano-oscillators both in the classical case of subthreshold ac excitation as well as in the suprathreshold case. The theoretical predictions are in very good agreement with simulations of the Landau-Lifshitz-Slonczewski dynamics.

  7. Logical stochastic resonance in triple-well potential systems driven by colored noise.

    PubMed

    Zhang, Huiqing; Xu, Yong; Xu, Wei; Li, Xiuchun

    2012-12-01

    In this work, the logic stochastic resonance (LSR) phenomenon in a class of stochastic triple-well potential systems is investigated. Approximate Fokker-Planck equation is first obtained by using decoupling approximation. Then, we show that LSR can be successfully induced by additive or multiplicative Gaussian colored noise in some cases. In the absence of internal noise, LSR implementation seems impossible for a?=?0 (The parameter a characterizes the depth of the potential well) since the two side wells are so deep that the particle cannot hop over the barrier into the middle well when the input signal is 0. With the increasing of a, the optimal noise band to yield flexible logic gates appears and moves to higher level of noise as the correlation time of noise increases. Compared with the Gaussian white noise, the reliable region in the parameter plane of potential depth parameter a and additive noise strength D first expands and then shrinks with increasing noise color. Furthermore, the effects of multiplicative Gaussian colored noise on LSR are investigated. It was found that the flexible and reliable logic behavior can be yielded for a?=?0 due to the fact that the multiplicative Gaussian colored noise strongly affects the shape of the potential function. With the increasing of a, i.e., a?=?0.25, multiplicative Gaussian white noise cannot yield desired logic behavior. Fortunately, LSR can also be expected by adjusting the correlation time of Gaussian colored noise. It can also be observed that the reliable region in the parameter plane of potential depth parameter a and multiplicative noise strength Q is small for the case of Gaussian white noise and it becomes larger with the increasing of noise color. PMID:23278065

  8. Modulation of human vestibular reflexes with increased postural threat.

    PubMed

    Horslen, Brian C; Dakin, Christopher J; Inglis, J Timothy; Blouin, Jean-Sébastien; Carpenter, Mark G

    2014-08-15

    Anxiety and arousal have been shown to facilitate human vestibulo-ocular reflexes, presumably through direct neural connections between the vestibular nuclei and emotional processing areas of the brain. However, the effects of anxiety, fear and arousal on balance-relevant vestibular reflexes are currently unknown. The purpose of this study was to manipulate standing height to determine whether anxiety and fear can modulate the direct relationship between vestibular signals and balance reflexes during stance. Stochastic vestibular stimulation (SVS; 2-25 Hz) was used to evoke ground reaction forces (GRF) while subjects stood in both LOW and HIGH surface height conditions. Two separate experiments were conducted to investigate the SVS-GRF relationship, in terms of coupling (coherence and cumulant density) and gain, in the medio-lateral (ML) and antero-posterior (AP) directions. The short- and medium-latency cumulant density peaks were both significantly increased in the ML and AP directions when standing in HIGH, compared to LOW, conditions. Likewise, coherence was statistically greater between 4.3 Hz and 6.7 Hz in the ML, and between 5.5 and 17.7 Hz in the AP direction. When standing in the HIGH condition, the gain of the SVS-GRF relationship was increased 81% in the ML direction, and 231% in the AP direction. The significant increases in coupling and gain observed in both experiments demonstrate that vestibular-evoked balance responses are augmented in states of height-induced postural threat. These data support the possibility that fear or anxiety-mediated changes to balance control are affected by altered central processing of vestibular information. PMID:24973412

  9. Enhancement of ohmic and stochastic heating by resonance effects in capacitive radio frequency discharges: a theoretical approach.

    PubMed

    Mussenbrock, T; Brinkmann, R P; Lieberman, M A; Lichtenberg, A J; Kawamura, E

    2008-08-22

    In low-pressure capacitive radio frequency discharges, two mechanisms of electron heating are dominant: (i) Ohmic heating due to collisions of electrons with neutrals of the background gas and (ii) stochastic heating due to momentum transfer from the oscillating boundary sheath. In this work we show by means of a nonlinear global model that the self-excitation of the plasma series resonance which arises in asymmetric capacitive discharges due to nonlinear interaction of plasma bulk and sheath significantly affects both Ohmic heating and stochastic heating. We observe that the series resonance effect increases the dissipation by factors of 2-5. We conclude that the nonlinear plasma dynamics should be taken into account in order to describe quantitatively correct electron heating in asymmetric capacitive radio frequency discharges. PMID:18764627

  10. Dissipation-induced coherence and stochastic resonance of an open two-mode Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Witthaut, D.; Trimborn, F.; Wimberger, S.

    2009-03-01

    We discuss the dynamics of a Bose-Einstein condensate in a double-well trap subject to phase noise and particle loss. The phase coherence of a weakly interacting condensate, experimentally measured via the contrast in an interference experiment, as well as the response to an external driving becomes maximal for a finite value of the dissipation rate matching the intrinsic time scales of the system. This can be understood as a stochastic resonance of the many-particle system. Even stronger effects are observed when dissipation acts in concurrence with strong interparticle interactions, restoring the purity of the condensate almost completely and increasing the phase coherence significantly. Our theoretical results are backed by Monte Carlo simulations, which show a good qualitative agreement and provide a microscopic explanation for the observed stochastic resonance effect.

  11. The effects of stochastic resonance electrical stimulation and neoprene sleeve on knee proprioception

    PubMed Central

    Collins, Amber T; Blackburn, J Troy; Olcott, Chris W; Dirschl, Douglas R; Weinhold, Paul S

    2009-01-01

    Background A variety of knee injuries and pathologies may cause a deficit in knee proprioception which may increase the risk of reinjury or the progression of disease. Stochastic resonance stimulation is a new therapy which has potential benefits for improving proprioceptive function. The objective of this study was to determine if stochastic resonance (SR) stimulation applied with a neoprene sleeve could improve knee proprioception relative to a no-stimulation/no-sleeve condition (control) or a sleeve alone condition in the normal, healthy knee. We hypothesized that SR stimulation when applied with a sleeve would enhance proprioception relative to the control and sleeve alone conditions. Methods Using a cross-over within subject design, twenty-four healthy subjects were tested under four combinations of conditions: electrical stimulation/sleeve, no stimulation/sleeve, no stimulation/no sleeve, and stimulation/no sleeve. Joint position sense (proprioception) was measured as the absolute mean difference between a target knee joint angle and the knee angle reproduced by the subject. Testing was conducted during both partial-weight bearing (PWB) and non-weight bearing (NWB) tasks. Differences in joint position sense between the conditions were evaluated by repeated-measures analysis of variance testing. Results Joint position sense error during the stimulation/sleeve condition (2.48° ± 1.32°) was found to be more accurate (P < 0.05) relative to the control condition (3.35° ± 1.63°) in the PWB task. No difference in joint position sense error was found between stimulation/sleeve and sleeve alone conditions for the PWB task. Joint position sense error was not found to differ between any of the conditions for the NWB task. Conclusion These results suggest that SR electrical stimulation when combined with a neoprene sleeve is an effective modality for enhancement of joint proprioception in the PWB knee. We believe these results suggest the need for further study of the potential of SR stimulation to correct proprioceptive deficits in a clinical population with knee injury/pathology or in subjects at risk of injury because of a proprioceptive deficit. PMID:19187538

  12. Stochastic resonance in simple analog circuits with a single operational amplifier having a double-well potential

    NASA Astrophysics Data System (ADS)

    Utagawa, Akira; Asai, Tetsuya; Amemiya, Yoshihito

    In this paper, we demonstrate stochastic resonance (SR) in a double-well potential system that can easily be implemented by a single operational amplifier. First, we propose a bistable mathematical model that is suitable for analog hardware implementation. Then we introduce an analog circuit for the model that is implemented by a single operational amplifier only, and demonstrate that the circuit exhibits the same SR behavior demonstrated in traditional double-well potential systems, through extensive numerical simulations and experiments.

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

    SciTech Connect

    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

    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)

  14. Stochastic Resonance in an Ensemble of Single-Electron Neuromorphic Devices and its Application to Competitive Neural Networks

    Microsoft Academic Search

    Ryo Kagaya; Takahide Oy; Tetsuya Asai; Yoshihito Amemiya

    2005-01-01

    Abstract—Neuromorphic,computing,based on single- electron circuit technology is gaining prominence,because of its massively increased computational efficiency and the increasing relevance of computer technology and nanotech- nology [1, 2]. The maximum impact of these technologies will be strongly felt when,single-electron circuits based on fault- and noise-tolerant neural structures can operate at room temperature. In this paper, inspired by stochastic resonance (SR) in

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

    PubMed Central

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

    2013-01-01

    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

  16. QUANTITATIVE MAGNETIC RESONANCE IMAGE ANALYSIS VIA THE EM ALGORITHM WITH STOCHASTIC VARIATION

    PubMed Central

    Zhang, Xiaoxi; Johnson, Timothy D.; Little, Roderick J. A.; Cao, Yue

    2009-01-01

    Quantitative Magnetic Resonance Imaging (qMRI) provides researchers insight into pathological and physiological alterations of living tissue, with the help of which, researchers hope to predict (local) therapeutic efficacy early and determine optimal treatment schedule. However, the analysis of qMRI has been limited to ad-hoc heuristic methods. Our research provides a powerful statistical framework for image analysis and sheds light on future localized adaptive treatment regimes tailored to the individual’s response. We assume in an imperfect world we only observe a blurred and noisy version of the underlying pathological/physiological changes via qMRI, due to measurement errors or unpredictable influences. We use a hidden Markov Random Field to model the spatial dependence in the data and develop a maximum likelihood approach via the Expectation-Maximization algorithm with stochastic variation. An important improvement over previous work is the assessment of variability in parameter estimation, which is the valid basis for statistical inference. More importantly, we focus on the expected changes rather than image segmentation. Our research has shown that the approach is powerful in both simulation studies and on a real dataset, while quite robust in the presence of some model assumption violations. PMID:20046819

  17. Stochastic resonance with Woods-Saxon potential for rolling element bearing fault diagnosis

    NASA Astrophysics Data System (ADS)

    Lu, Siliang; He, Qingbo; Kong, Fanrang

    2014-04-01

    This paper proposes a weak signal detection strategy for rolling element bearing fault diagnosis by investigating a new mechanism to realize stochastic resonance (SR) based on the Woods-Saxon (WS) potential. The WS potential has the distinct structure with smooth potential bottom and steep potential wall, which guarantees a stable particle motion within the potential and avoids the unexpected noises for the SR system. In the Woods-Saxon SR (WSSR) model, the output signal-to-noise ratio (SNR) can be optimized just by tuning the WS potential's parameters, which delivers the most significant merit that the limitation of small parameter requirement of the classical bistable SR can be overcome, and thus a wide range of driving frequencies can be detected via the SR model. Furthermore, the proposed WSSR model is also insensitive to the noise, and can detect the weak signals with different noise levels. Additionally, the WS potential can be designed accurately due to its parameter independence, which implies that the proposed method can be matched to different input signals adaptively. With these properties, the proposed weak signal detection strategy is indicated to be beneficial to rolling element bearing fault diagnosis. Both the simulated and the practical bearing fault signals verify the effectiveness and efficiency of the proposed WSSR method in comparison with the traditional bistable SR method.

  18. Enhancement of information transmission with stochastic resonance in hippocampal CA1 neuron network.

    PubMed

    Kawaguchi, Minato; Mino, Hiroyuki; Durand, Dominique M

    2008-01-01

    Stochastic resonance (SR) has been shown to improve the detection of subthreshold neural signals in uncorrelated noise. It is yet unclear if and how interactions within a population of neurons can improve information processing in neural networks. In this paper, we investigate the effect of the number of neurons on information transmission in an array of hippocampal CA1 neuron models, i.e., array-enhanced SR (AESR). In computer simulations, the sub-threshold synaptic current (signal) generated by a filtered homogeneous Poisson process was applied to a distal position in each of the apical dendrites, while the background synaptic currents (uncorrelated noise) were presented to a proximal or middle point in each of the dendrites. The transmembrane potentials were recorded at one of the somas in the array of CA1 neuron models, in order to find spike firings and likewise to estimate the total and noise entropies calculated from those spike firing times. The results show that the information rate estimated at the population of the CA1 neuron models is maximized at a specific amplitude of uncorrelated noise, implying AESR. The results further show that the maximum information rate is increased as the number of neurons is increased. It is concluded that AESR can be an important role in information processing is neural systems and that the AESR is modulated by the number of neurons within the network. PMID:19163829

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

    SciTech Connect

    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

    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.

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

    PubMed

    Iliopoulos, Fivos; Nierhaus, Till; Villringer, Arno

    2014-03-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  2. Theory of Stochastic Dipolar Recoupling in Solid State Nuclear Magnetic Resonance

    PubMed Central

    Tycko, Robert

    2008-01-01

    Dipolar recoupling techniques in solid state nuclear magnetic resonance (NMR) consist of radio-frequency (rf) pulse sequences applied in synchrony with magic-angle spinning (MAS) that create non-zero average magnetic dipole-dipole couplings under MAS. Stochastic dipolar recoupling (SDR) is a variant in which randomly chosen rf carrier frequency offsets are introduced to cause random phase modulations of individual pairwise couplings in the dipolar spin Hamiltonian. Several aspects of SDR are investigated through analytical theory and numerical simulations: (1) An analytical expression for the evolution of nuclear spin polarization under SDR in a two-spin system is derived and verified through simulations, which show a continuous evolution from coherent, oscillatory polarization exchange to incoherent, exponential approach to equilibrium as the range of random carrier offsets (controlled by a parameter fmax) increases; (2) In a many-spin system, polarization transfers under SDR are shown to be described accurately by a rate matrix in the limit of large fmax, with pairwise transfer rates that are proportional to the inverse sixth power of pairwise internuclear distances; (3) Quantum mechanical interferences among non-commuting pairwise dipole-dipole couplings, which are a complicating factor in solid state NMR studies of molecular structures by traditional dipolar recoupling methods, are shown to be absent from SDR data in the limit of large fmax, provided that coupled nuclei have distinct NMR chemical shifts. PMID:18085769

  3. Stochastic resonance of charge carriers diffusing in a nonhomogeneous medium with nonhomogeneous temperature

    NASA Astrophysics Data System (ADS)

    Aragie, Berhanu; Tatek, Yergou B.; Bekele, Mulugeta

    2014-05-01

    We investigate the dynamics of charge carriers hopping from one trap to the other trap along an n-type semiconductor layer consisting of a spatially nonhomogeneous trap distribution of depth ? assisted by thermal noise. The trap profile is denser at the center and decays as one moves outward. In presence of a uniform background temperature, the charge carriers tend to accumulate around the center. Moreover, applying a nonhomogeneous temperature which is hot at the location of the maximum of trap density, results in a new redistribution of charge carriers which pile up around two points symmetrically positioned with respect to the center of the semiconductor layer making the system to behave like a bistable potential. The thermally activated rate of hopping of charge carriers as a function of the model parameters is studied in the high barrier limit. Using the two-state approximation, the stochastic resonance (SR) of the charge carriers dynamics in the presence of time varying external signal is also investigated.

  4. The role of damping on Stochastic Resonance in a periodic potential

    NASA Astrophysics Data System (ADS)

    Saikia, Shantu

    2014-12-01

    The role of damping on the phenomenon of Stochastic Resonance (SR) in a driven underdamped periodic potential system is studied. Using input energy per period of external drive as a quantifier, SR is observed in the model multistable system in the high frequency regime, due to the noise assisted transitions of the particle between two distinct dynamical states of trajectories, characterized by their definite amplitude, energy and phase. SR is observed in this system only when the damping is lesser than a particular maximum limit. The stability of the two states and hence the nature of SR depends upon the damping parameter ? and the amplitude of drive. The input energy distributions at different temperatures across the SR peak, bear characteristic features associated with SR. The average input energy per period of external drive peaks as a function ?. The phase difference ?¯ between the particle's average response amplitude and the external drive plotted as a function of ? shows an inflection point corresponding to the peak in . Thus inflection in ?¯ is not exclusive only to SR peaks.

  5. Vestibular-evoked myogenic potentials in vestibular migraine

    Microsoft Academic Search

    Bernhard Baier; N. Stieber; M. Dieterich

    2009-01-01

    Sound-induced vestibular-evoked myogenic potentials (VEMPs) can be used to investigate saccular function, measured from the\\u000a tonically contracted sternocleidomastoid muscles (SCM) in response to loud sound stimuli. The aim of the present study was\\u000a to assess VEMPs in patients with vestibular migraine and to determine whether saccular function is affected by the disease.\\u000a Furthermore, tests such as tilts of subjective visual

  6. Zero-quantum stochastic dipolar recoupling in solid state nuclear magnetic resonance

    PubMed Central

    Qiang, Wei; Tycko, Robert

    2012-01-01

    We present the theoretical description and experimental demonstration of a zero-quantum stochastic dipolar recoupling (ZQ-SDR) technique for solid state nuclear magnetic resonance (NMR) studies of 13C-labeled molecules, including proteins, under magic-angle spinning (MAS). The ZQ-SDR technique combines zero-quantum recoupling pulse sequence blocks with randomly varying chemical shift precession periods to create randomly amplitude- and phase-modulated effective homonuclear magnetic dipole-dipole couplings. To a good approximation, couplings between different 13C spin pairs become uncorrelated under ZQ-SDR, leading to spin dynamics (averaged over many repetitions of the ZQ-SDR sequence) that are fully described by an orientation-dependent N × N polarization transfer rate matrix for an N-spin system, with rates that are inversely proportional to the sixth power of internuclear distances. Suppression of polarization transfers due to non-commutivity of pairwise couplings (i.e., dipolar truncation) does not occur under ZQ-SDR, as we show both analytically and numerically. Experimental demonstrations are reported for uniformly 13C-labeled L-valine powder (at 14.1 T and 28.00 kHz MAS), uniformly 13C-labeled protein GB1 in microcrystalline form (at 17.6 T and 40.00 kHz MAS), and partially labeled 13C-labeled protein GB1 (at 14.1 T and 40.00 kHz MAS). The experimental results verify that spin dynamics under ZQ-SDR are described accurately by rate matrices and suggest the utility of ZQ-SDR in structural studies of 13C-labeled solids. PMID:22979851

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

    NASA Astrophysics Data System (ADS)

    Morse, Robert P.; Roper, Peter

    2000-05-01

    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.

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

    PubMed Central

    2013-01-01

    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

  9. Zero-quantum stochastic dipolar recoupling in solid state nuclear magnetic resonance.

    PubMed

    Qiang, Wei; Tycko, Robert

    2012-09-14

    We present the theoretical description and experimental demonstration of a zero-quantum stochastic dipolar recoupling (ZQ-SDR) technique for solid state nuclear magnetic resonance (NMR) studies of (13)C-labeled molecules, including proteins, under magic-angle spinning (MAS). The ZQ-SDR technique combines zero-quantum recoupling pulse sequence blocks with randomly varying chemical shift precession periods to create randomly amplitude- and phase-modulated effective homonuclear magnetic dipole-dipole couplings. To a good approximation, couplings between different (13)C spin pairs become uncorrelated under ZQ-SDR, leading to spin dynamics (averaged over many repetitions of the ZQ-SDR sequence) that are fully described by an orientation-dependent N × N polarization transfer rate matrix for an N-spin system, with rates that are inversely proportional to the sixth power of internuclear distances. Suppression of polarization transfers due to non-commutivity of pairwise couplings (i.e., dipolar truncation) does not occur under ZQ-SDR, as we show both analytically and numerically. Experimental demonstrations are reported for uniformly (13)C-labeled L-valine powder (at 14.1 T and 28.00 kHz MAS), uniformly (13)C-labeled protein GB1 in microcrystalline form (at 17.6 T and 40.00 kHz MAS), and partially labeled (13)C-labeled protein GB1 (at 14.1 T and 40.00 kHz MAS). The experimental results verify that spin dynamics under ZQ-SDR are described accurately by rate matrices and suggest the utility of ZQ-SDR in structural studies of (13)C-labeled solids. PMID:22979851

  10. Aging of vestibular function evaluated using correlational vestibular autorotation test

    PubMed Central

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

    2014-01-01

    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

  11. How a single stretched polymer responds coherently to a minute oscillation in fluctuating environments: an entropic stochastic resonance.

    PubMed

    Kim, Won Kyu; Sung, Wokyung

    2012-08-21

    Within the cell, biopolymers are often situated in constrained, fluid environments, e.g., cytoskeletal networks, stretched DNAs in chromatin. It is of paramount importance to understand quantitatively how they, utilizing their flexibility, optimally respond to a minute signal, which is, in general, temporally fluctuating far away from equilibrium. To this end, we analytically study viscoelastic response and associated stochastic resonance in a stretched single semi-flexible chain to an oscillatory force or electric field. Including hydrodynamic interactions between chain segments, we evaluate dynamics of the polymer extension in coherent response to the force or field. We find power amplification factor of the response at a noise-strength (temperature) can attain the maximum that grows as the chain length increases, indicative of an entropic stochastic resonance (ESR). In particular for a charged chain under an electric field, we find that the maximum also occurs at an optimal chain length, a new feature of ESR. The hydrodynamic interaction is found to enhance the power amplification, representing unique polymer cooperativity which the fluid background imparts despite its overdamping nature. For the slow oscillatory force, the resonance behavior is explained by the chain undulation of the longest wavelength. This novel ESR phenomenon suggests how a biopolymer self-organizes in an overdamping environment, utilizing its flexibility and thermal fluctuations. PMID:22920141

  12. Spatio-temporal pattern of vestibular information processing after brief caloric stimulation.

    PubMed

    Marcelli, Vincenzo; Esposito, Fabrizio; Aragri, Adriana; Furia, Teresa; Riccardi, Pasquale; Tosetti, Michela; Biagi, Laura; Marciano, Elio; Di Salle, Francesco

    2009-05-01

    Processing of vestibular information at the cortical and subcortical level is essential for head and body orientation in space and self-motion perception, but little is known about the neural dynamics of the brain regions of the vestibular system involved in this task. Neuroimaging studies using both galvanic and caloric stimulation have shown that several distinct cortical and subcortical structures can be activated during vestibular information processing. The insular cortex has been often targeted and presented as the central hub of the vestibular cortical system. Since very short pulses of cold water ear irrigation can generate a strong and prolonged vestibular response and a nystagmus, we explored the effects of this type of caloric stimulation for assessing the blood-oxygen-level-dependent (BOLD) dynamics of neural vestibular processing in a whole-brain event-related functional magnetic resonance imaging (fMRI) experiment. We evaluated the spatial layout and the temporal dynamics of the activated cortical and subcortical regions in time-locking with the instant of injection and were able to extract a robust pattern of neural activity involving the contra-lateral insular cortex, the thalamus, the brainstem and the cerebellum. No significant correlation with the temporal envelope of the nystagmus was found. The temporal analysis of the activation profiles highlighted a significantly longer duration of the evoked BOLD activity in the brainstem compared to the insular cortex suggesting a functional de-coupling between cortical and subcortical activity during the vestibular response. PMID:18342473

  13. Vestibular functions in motion sickness susceptible individuals

    Microsoft Academic Search

    Fuat Buyuklu; Erkan Tarhan; Levent Ozluoglu

    2009-01-01

    There exists no functional guide that can serve as a diagnostic tool for individual susceptibility to motion sickness (MS).\\u000a We evaluated vestibular system functioning via a caloric test (which assesses functioning of the superior vestibular nerve)\\u000a and the vestibular-evoked myogenic potentials (VEMP) test (which assesses inferior vestibular nerve functioning) in 20 MS\\u000a susceptible and 20 nonsusceptible individuals. Susceptibility to MS

  14. Bistable generalised Langevin dynamics driven by correlated noise possessing a long jump distribution: barrier crossing and stochastic resonance

    NASA Astrophysics Data System (ADS)

    Srokowski, Tomasz

    2013-05-01

    The generalised Langevin equation with a retarded friction and a double-well potential is solved. The random force is modelled by a multiplicative noise with long jumps. Probability density distributions converge with time to a distribution similar to a Gaussian but tails have a power-law form. Dependence of the mean first passage time on model parameters is discussed. Properties of the stochastic resonance, emerging as a peak in the plot of the spectral amplification against the temperature, are discussed for various sets of the model parameters. The amplification rises with the memory and is largest for the cases corresponding to the large passage time.

  15. The Critical Effects of Time Delay and Noise Correlation on Stochastic Resonance in AN Asymmetric Bistable System

    NASA Astrophysics Data System (ADS)

    Jia, Zheng-Lin; Mei, Dong-Cheng

    We investigate the effects of time delay and noise correlation on the stochastic resonance induced by a multiplicative signal in an asymmetric bistable system. By the two-state theory and small delay approximation, the expression of the output signal-to-noise ratio (SNR) is obtained in the adiabatic limit. The results show that SNR as a function of the multiplicative noise intensity D shows a transition from two peaks to one peak with the decreasing of cross-correlation strength ? and the increasing of delay time ?. Moreover, there are the doubly critical phenomena for SNR versus ? and ?, and SNR versus D and ? (additive noise intensity).

  16. Stochastic resonance whole-body vibration training for chair rising performance on untrained elderly: a pilot study.

    PubMed

    Rogan, Slavko; Hilfiker, Roger; Schmid, Stefan; Radlinger, Lorenz

    2012-01-01

    The present randomized controlled pilot study was conducted to determine the feasibility of the study protocol and the effects of four-week-long sessions involving stochastic resonance whole-body vibration (SR-WBV) training on chair rising in elderly individuals. Twenty elderly participants were divided into a SR-WBV group or a sham group. Peak force, rate of force development, rising time, time to stabilization and total time during chair rising performance were investigated. Intraclass correlation coefficients, Mann-Whitney U-tests and Wilcoxon signed-ranked tests were used. Low volume SR-WBV over 12 training sessions might provide a safe treatment method. PMID:22425243

  17. Modeling the vestibular evoked myogenic potential

    Microsoft Academic Search

    Bernd Lütkenhöner; Wolfgang Stoll; Türker Basel

    2010-01-01

    Measuring the vestibular evoked myogenic potential (VEMP) promises to become a routine method for assessing vestibular function, although the technique is not yet standardized. To overcome the problem that the VEMP amplitude depends not only on the inhibition triggered by the acoustic stimulation of the vestibular end organs in the inner ear, but also on the tone of the muscle

  18. RECORDING OF VESTIBULAR EVOKED MYOGENIC POTENTIALS

    Microsoft Academic Search

    A. A. Sazgar; K. Akrami; S. Akrami; A. R. Karimi Yazdi

    It has been shown recently that loud clicks evoke myogenic potentials in the tonically contracting sternocleidomastoid muscles. Studies have suggested that these potentials are of vestibular origin, especially of the saccule and inferior vestibular nerve. A pilot study was undertaken in our hospital to record vestibular evoked myogenic potentials (VEMP) for the first time in Iran. Eighteen healthy volunteers (32

  19. Intrinsic Firing Dynamics of Vestibular Nucleus Neurons

    Microsoft Academic Search

    Chris Sekirnjak

    2002-01-01

    Individual brainstem neurons involved in vestibular reflexes respond to identical head movements with a wide range of firing responses. This diversity of firing dynamics has been commonly assumed to arise from differences in the types of vestibular nerve inputs to vestibular nucleus neurons. In this study we show that, independent of the nature of inputs, the intrinsic membrane properties of

  20. Habituation of vestibular responses: An overview

    NASA Technical Reports Server (NTRS)

    Collins, W. E.

    1973-01-01

    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.

  1. Ocular Vestibular Evoked Myogenic Potentials

    PubMed Central

    Felipe, Lilian; Kingma, Herman

    2013-01-01

    Introduction?Diagnostic testing of the vestibular system is an essential component of treating patients with balance dysfunction. Until recently, testing methods primarily evaluated the integrity of the horizontal semicircular canal, which is only a portion of the vestibular system. Recent advances in technology have afforded clinicians the ability to assess otolith function through vestibular evoked myogenic potential (VEMP) testing. VEMP testing from the inferior extraocular muscles of the eye has been the subject of interest of recent research. Objective?To summarize recent developments in ocular VEMP testing. Results?Recent studies suggest that the ocular VEMP is produced by otolith afferents in the superior division of the vestibular nerve. The ocular VEMP is a short latency potential, composed of extraocular myogenic responses activated by sound stimulation and registered by surface electromyography via ipsilateral otolithic and contralateral extraocular muscle activation. The inferior oblique muscle is the most superficial of the six extraocular muscles responsible for eye movement. Therefore, measurement of ocular VEMPs can be performed easily by using surface electrodes on the skin below the eyes contralateral to the stimulated side. Conclusion?This new variation of the VEMP procedure may supplement conventional testing in difficult to test populations. It may also be possible to use this technique to evaluate previously inaccessible information on the vestibular system. PMID:25992068

  2. Ocular vestibular evoked myogenic potentials.

    PubMed

    Felipe, Lilian; Kingma, Herman

    2014-01-01

    Introduction?Diagnostic testing of the vestibular system is an essential component of treating patients with balance dysfunction. Until recently, testing methods primarily evaluated the integrity of the horizontal semicircular canal, which is only a portion of the vestibular system. Recent advances in technology have afforded clinicians the ability to assess otolith function through vestibular evoked myogenic potential (VEMP) testing. VEMP testing from the inferior extraocular muscles of the eye has been the subject of interest of recent research. Objective?To summarize recent developments in ocular VEMP testing. Results?Recent studies suggest that the ocular VEMP is produced by otolith afferents in the superior division of the vestibular nerve. The ocular VEMP is a short latency potential, composed of extraocular myogenic responses activated by sound stimulation and registered by surface electromyography via ipsilateral otolithic and contralateral extraocular muscle activation. The inferior oblique muscle is the most superficial of the six extraocular muscles responsible for eye movement. Therefore, measurement of ocular VEMPs can be performed easily by using surface electrodes on the skin below the eyes contralateral to the stimulated side. Conclusion?This new variation of the VEMP procedure may supplement conventional testing in difficult to test populations. It may also be possible to use this technique to evaluate previously inaccessible information on the vestibular system. PMID:25992068

  3. Vestibular function in superficial siderosis

    PubMed Central

    2013-01-01

    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

  4. Procedures for restoring vestibular disorders

    PubMed Central

    Walther, Leif Erik

    2005-01-01

    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

  5. Penaeus orientolis prawn freshness rapid determination method based on electronic nose and non-linear stochastic resonance technique.

    PubMed

    Wei, Liu; Yuanyuan, Han; Yanping, Cai; Jiaojiao, Jin; Guohua, Hui

    2015-01-01

    In this paper, Penaeus orientolis prawn freshness rapid determination method using electronic nose (e-nose) and non-linear data processing technique is studied. E-nose responses to prawns stored at 4 °C are measured. Meanwhile, physical/chemical indexes (firmness, pH, total volatile basic nitrogen (TVB-N), total viable count (TVC), and human sensory evaluation) are examined to provide freshness references for e-nose analysis. E-nose measurement data is analyzed by principal component analysis (PCA), stochastic resonance (SR), and double-layered cascaded serial stochastic resonance (DCSSR). PCA partially discriminates prawns under different storage time. SR and DCSSR signal-to-noise ratio (SNR) spectrum eigen values discriminate prawns successfully. Multi-variables regressions (MVR) are conducted between physical/chemical indexes and SR/DCSSR output SNR minimal (SNR-Min) values. Results indicate that SNR-Min values present more significant linearity relation with physical/chemical indexes. Prawn freshness forecasting model is developed via Harris fitting regression on DCSSR SNR-Min values. Validating experiments demonstrate that forecasting accuracy of this model is 94.29%. PMID:25551520

  6. Enhancement of information transmission with stochastic resonance in hippocampal CA1 neuron models: effects of noise input location.

    PubMed

    Kawaguchi, Minato; Mino, Hiroyuki; Durand, Dominique M

    2007-01-01

    Stochastic resonance (SR) has been shown to enhance the signal to noise ratio or detection of signals in neurons. It is not yet clear how this effect of SR on the signal to noise ratio affects signal processing in neural networks. In this paper, we investigate the effects of the location of background noise input on information transmission in a hippocampal CA1 neuron model. In the computer simulation, random sub-threshold spike trains (signal) generated by a filtered homogeneous Poisson process were presented repeatedly to the middle point of the main apical branch, while the homogeneous Poisson shot noise (background noise) was applied to a location of the dendrite in the hippocampal CA1 model consisting of the soma with a sodium, a calcium, and five potassium channels. The location of the background noise input was varied along the dendrites to investigate the effects of background noise input location on information transmission. The computer simulation results show that the information rate reached a maximum value for an optimal amplitude of the background noise amplitude. It is also shown that this optimal amplitude of the background noise is independent of the distance between the soma and the noise input location. The results also show that the location of the background noise input does not significantly affect the maximum values of the information rates generated by stochastic resonance. PMID:18003553

  7. Spike-interval triggered averaging reveals a quasi-periodic spiking alternative for stochastic resonance in catfish electroreceptors.

    PubMed

    Lankheet, Martin J M; Klink, P Christiaan; Borghuis, Bart G; Noest, André J

    2012-01-01

    Catfish detect and identify invisible prey by sensing their ultra-weak electric fields with electroreceptors. Any neuron that deals with small-amplitude input has to overcome sensitivity limitations arising from inherent threshold non-linearities in spike-generation mechanisms. Many sensory cells solve this issue with stochastic resonance, in which a moderate amount of intrinsic noise causes irregular spontaneous spiking activity with a probability that is modulated by the input signal. Here we show that catfish electroreceptors have adopted a fundamentally different strategy. Using a reverse correlation technique in which we take spike interval durations into account, we show that the electroreceptors generate a supra-threshold bias current that results in quasi-periodically produced spikes. In this regime stimuli modulate the interval between successive spikes rather than the instantaneous probability for a spike. This alternative for stochastic resonance combines threshold-free sensitivity for weak stimuli with similar sensitivity for excitations and inhibitions based on single interspike intervals. PMID:22403709

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

    PubMed

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

    2014-02-01

    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

  9. Vestibular findings in military band musicians.

    PubMed

    Zeigelboim, Bianca Simone; Gueber, Crislaine; Silva, Thanara Pruner da; Liberalesso, Paulo Breno Noronha; Gonçalves, Claudia Giglio de Oliveira; Faryniuk, João Henrique; Marques, Jair Mendes; Jurkiewicz, Ari Leon

    2014-04-01

    Introduction?Exposure to music is the subject of many studies because it is related to an individual's professional and social activities. Objectives?Evaluate the vestibular behavior in military band musicians. Methods?A retrospective cross-sectional study was performed. Nineteen musicians with ages ranging from 21 to 46 years were evaluated (average?=?33.7 years and standard deviation?=?7.2 years). They underwent anamnesis and vestibular and otolaryngologic evaluation through vectoelectronystagmography. Results?The most evident otoneurologic symptoms in the anamnesis were tinnitus (84.2%), hearing difficulties (47.3%), dizziness (36.8%), headache (26.3%), intolerance to intense sounds (21.0%), and earache (15.7%). Seven musicians (37.0%) showed vestibular abnormality, which occurred in the caloric test. The abnormality was more prevalent in the peripheral vestibular system, and there was a predominance of irritative peripheral vestibular disorders. Conclusion?The alteration in vestibular exam occurred in the caloric test (37.0%). There were changes in the prevalence of peripheral vestibular system with a predominance of irritative vestibular dysfunction. Dizziness was the most significant symptom for the vestibular test in correlation with neurotologic symptoms. The present study made it possible to verify the importance of the labyrinthine test, which demonstrates that this population should be better studied because the systematic exposure to high sound pressure levels may cause major vestibular alterations. PMID:25992076

  10. Vestibular Stimulation Attenuates Unrealistic Optimism RUNNING HEAD: Vestibular Stimulation and Optimism

    E-print Network

    Royal Holloway, University of London

    . Moreover, anosognosia is temporarily abolished by vestibular stimulation, particularly by irrigation Illusions; Vestibular Stimulation; Caloric Irrigation; Anosognosia. #12;3 1. Introduction Unrealistic, recently there has been growing interest in relevant neural and pharmacological mechanisms (Sharot et al

  11. System identification of the vestibular ocular reflex via visual and vestibular co-stimulation

    E-print Network

    Tangorra, James Louis, 1967-

    2003-01-01

    The study of eye motions involved in the vestibular ocular reflex (VOR) is a key tool for understanding the performance of the vestibular system and for the diagnosis of dysfunction. Limitations in experimental equipment ...

  12. Detection of small single-cycle signals by stochastic resonance using a bistable superconducting quantum interference device

    NASA Astrophysics Data System (ADS)

    Sun, Guozhu; Zhai, Jiquan; Wen, Xueda; Yu, Yang; Kang, Lin; Xu, Weiwei; Chen, Jian; Wu, Peiheng; Han, Siyuan

    2015-04-01

    We propose and experimentally demonstrate detecting small single-cycle and few-cycle signals by using the symmetric double-well potential of a radio frequency superconducting quantum interference device (rf-SQUID). We show that the response of this bistable system to single- and few-cycle signals has a non-monotonic dependence on the noise strength. The response, measured by the probability of transition from initial potential well to the opposite one, becomes maximum when the noise-induced transition rate between the two stable states of the rf-SQUID is comparable to the signal frequency. Comparison to numerical simulations shows that the phenomenon is a manifestation of stochastic resonance.

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

    PubMed

    Moix, Jeremy M; Ma, Jian; Cao, Jianshu

    2015-03-01

    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 Förster 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 (see Paper II) is the only perturbative method capable of generating uniformly reliable energy transfer rates and emission spectra across a broad range of system parameters. PMID:25747062

  14. A new evaluation of vestibular compensation.

    PubMed

    Sasaki, O; Taguchi, K

    1994-01-01

    Vestibular compensation process in six patients was examined by means of static (SPG) and kinetic posturography (KPG). SPG was recorded by a stabilometer during standing and KPG was recorded by POLGON so that angular change of shoulder in the frontal plane was measured during stepping. The subjects included three cases with vestibular neuronitis, three cases with bilateral vestibular loss. In vestibular neuronitis, SPG improved earlier than KPG. As a result of vestibular training, initial high levels of SPG and KPG fall precipitously and in the case with sequela, a remarkably high level of KPG gradually decreased. In bilateral vestibular loss, abnormality of KPG tended to persist and those results would be due to the disappearance of a hip strategy. The effect of training upon the case which started from the early days was not shown. However, the case which started from 10 months after the onset showed remarkable improvement of SPG and KPG. PMID:7872890

  15. Co-existing responses and stochastic resonance in post-buckled structures: A combined numerical and experimental study

    NASA Astrophysics Data System (ADS)

    Wiebe, R.; Spottswood, S. M.

    2014-09-01

    Much of what is known about co-existing responses in nonlinear systems under both deterministic and random dynamic loading is limited to phenomenological investigations of discrete systems, most commonly, the Duffing equation. From these results alone, it is difficult to extrapolate the behavior of the distributed nonlinear systems more commonly seen in real structures such as buckled beams and curved panels. This is because, beyond the simple increase in dimension, real systems bring with them imperfections and more complex forms of energy dissipation. The possibility of co-existing responses, particularly in the case of simultaneous “safe” and “unsafe” solutions (e.g. snap-through and non-snap-through), poses potential problems for engineers as it multiplies the workload, since one must be very careful to ensure that a particular simulation or experiment has captured the most critical response. Even in the case where random forces dominate the overall loading of a system, a situation in which one might anticipate an equally random response, a very small harmonic component can have an influence beyond its proportion. This effect, known as stochastic resonance, is quite counterintuitive to the analyst more familiar with linear systems where the principles of superposition and scalar multiplication of solutions make this impossible. In this paper, the effect of the damping and noise level on the number of co-existing responses in nonlinear systems is investigated. Stochastic resonance is also demonstrated, first with a double-well Duffing oscillator, and then it is shown to exist experimentally, we believe for the first time, on a macroscopic structure, that being, an (imperfect) buckled beam.

  16. Linear addition of optokinetic and vestibular signals in the vestibular nucleus

    Microsoft Academic Search

    D. A. Robinson

    1977-01-01

    A simple model of the vestibuloocular reflex and the optokinetic system was used to simulate recent data on visual and vestibular responses of neurons in the vestibular nucleus. Contrary to a previous interpretation, the results support the hypothesis that the optokinetic and semicircular canal signals are combined simply by linear addition on the cells of the vestibular nucleus.

  17. Minimalistic behavioral rule derived from bacterial chemotaxis in a stochastic resonance setup.

    PubMed

    Ikemoto, Shuhei; DallaLibera, Fabio; Hosoda, Koh; Ishiguro, Hiroshi

    2012-02-01

    Animals are able to cope with the noise, uncertainties, and complexity of the real world. Often even elementary living beings, equipped with very limited sensory organs, are able to reach regions favorable to their existence, using simple stochastic policies. In this paper we discuss a minimalistic stochastic behavioral rule, inspired from bacteria chemotaxis, which is able to increase the value of a specified evaluation function in a similar manner. In particular, we prove that, under opportune assumptions, the direction that is taken with maximum probability by an agent that follows this rule corresponds to the optimal direction. The rule does not require a specific agent dynamics, needs no memory for storing observed states, and works in generic n-dimensional spaces. It thus reveals itself interesting for the control of simple sensing robots as well. PMID:22463242

  18. Vestibular loss disrupts daily rhythm in rats.

    PubMed

    Martin, T; Mauvieux, B; Bulla, J; Quarck, G; Davenne, D; Denise, P; Philoxène, B; Besnard, S

    2015-02-01

    Hypergravity disrupts the circadian regulation of temperature (Temp) and locomotor activity (Act) mediated through the vestibular otolithic system in mice. In contrast, we do not know whether the anatomical structures associated with vestibular input are crucial for circadian rhythm regulation at 1 G on Earth. In the present study we observed the effects of bilateral vestibular loss (BVL) on the daily rhythms of Temp and Act in semipigmented rats. Our model of vestibular lesion allowed for selective peripheral hair cell degeneration without any other damage. Rats with BVL exhibited a disruption in their daily rhythms (Temp and Act), which were replaced by a main ultradian period (? <20 h) for 115.8 ± 68.6 h after vestibular lesion compared with rats in the control group. Daily rhythms of Temp and Act in rats with BVL recovered within 1 wk, probably counterbalanced by photic and other nonphotic time cues. No correlation was found between Temp and Act daily rhythms after vestibular lesion in rats with BVL, suggesting a direct influence of vestibular input on the suprachiasmatic nucleus. Our findings support the hypothesis that the vestibular system has an influence on daily rhythm homeostasis in semipigmented rats on Earth, and raise the question of whether daily rhythms might be altered due to vestibular pathology in humans. PMID:25505031

  19. Movement Symmetries and the Mammalian Vestibular System

    NASA Astrophysics Data System (ADS)

    McCollum, Gin; Boyle, Richard

    2000-03-01

    Unity of movement requires vertebrates to have an ability to symmetrize along the midline. For example, human erect stance involves symmetry with respect to gravity. The mammalian vestibular system provides a mechanism for maintaining symmetries, which is also open to influence and adaptation by the rest of the organism. The vestibular system includes the inner ear endorgans and central nuclei, along with projections to oculomotor, cerebellar, thalamic, and spinal motor centers. The vestibular endorgans - the semicircular canals and the otoliths - use sensory hairs to register inertia. The vestibular endorgans are right-left symmetric and the semicircular canals form an approximately orthogonal coordinate system for angular motion. Primary afferent axons project from the endorgans to the vestibular nuclei (and a few other places). The vestibular nuclei integrate vestibular, visual, and somatosensory signals, along with a proposed copy of the voluntary motor command and signals from other central structures. The relationship between the canals and the otoliths gives rise to symmetries among neurons, in the organization among the several vestibular nuclei, and in the projections from the vestibular nuclei. These symmetries organize the space of body movements so that functional relationships are maintained in spite of the many free variables of body movement. They also provide a foundation for adaptive reinterpretation of the relationship between canal and otolith signals, for example in freefall.

  20. A vestibular phenotype for Waardenburg syndrome?

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  1. Vestibular suppression during space flight.

    PubMed

    Watt, Douglas; Lefebvre, Luc

    2003-01-01

    Normal movements performed while voluntarily fixing the head to the torso can lead to motion sickness in susceptible individuals. The underlying mechanism may involve excessive suppression of vestibular responses. A similar motor strategy is often adopted in the early days of a space flight and might contribute to the development of space motion sickness. In a recent experiment, we monitored the eye, head and upper torso rotations of four Life and Microgravity Spacelab crew members. For the purposes of this study, all data were excluded except for periods during which the subject was performing pure yaw-axis head movements. All subjects showed a significant increase in gaze slip on the first day of their mission, suggesting that increased vestibular suppression was occurring. Furthermore, this amount of increased suppression would have been more than adequate to produce motion sickness in susceptible individuals on the ground. The results support the theory of two, independent mechanisms for space motion sickness. PMID:15096678

  2. Electrical Stimulation to Restore Vestibular Function – Development of a 3-D Vestibular Prosthesis

    PubMed Central

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

    2009-01-01

    Patients who fail to compensate for bilateral loss of vestibular sensory function are disabled by disequilibrium and illusory movement of the visual field during head movement. An implantable prosthesis that restores vestibular sensation could significantly improve quality of life for these patients. To be effective, such a device should encode head rotation in all 3 dimensions. We describe the 3-dimensional angular vestibulo-ocular reflex of normal chinchillas and vestibular-deficient chinchillas undergoing functional electrical stimulation of the vestibular nerve. We also describe the design and fabrication of a head-mounted, 8 electrode vestibular prosthesis that encodes head movement in 3 dimensions. PMID:17281986

  3. Stochastic, resonance-free multiple time-step algorithm for molecular dynamics with very large time steps

    NASA Astrophysics Data System (ADS)

    Leimkuhler, Ben; Margul, Daniel T.; Tuckerman, Mark E.

    2013-12-01

    Molecular dynamics is one of the most commonly used approaches for studying the dynamics and statistical distributions of many physical, chemical, and biological systems using atomistic or coarse-grained models. It is often the case, however, that the interparticle forces drive motion on many time scales, and the efficiency of a calculation is limited by the choice of time step, which must be sufficiently small that the fastest force components are accurately integrated. Multiple time-stepping algorithms partially alleviate this inefficiency by assigning to each time scale an appropriately chosen step-size. However, such approaches are limited by resonance phenomena, wherein motion on the fastest time scales limits the step sizes associated with slower time scales. In atomistic models of biomolecular systems, for example, resonances limit the largest time step to around 5-6 fs. In this paper, we introduce a set of stochastic isokinetic equations of motion that are shown to be rigorously ergodic and that can be integrated using a multiple time-stepping algorithm that can be easily implemented in existing molecular dynamics codes. The technique is applied to a simple, illustrative problem and then to a more realistic system, namely, a flexible water model. Using this approach outer time steps as large as 100 fs are shown to be possible.

  4. Vestibular paroxysmia in children: a treatable cause of short vertigo attacks.

    PubMed

    Lehnen, Nadine; Langhagen, Thyra; Heinen, Florian; Huppert, Doreen; Brandt, Thomas; Jahn, Klaus

    2015-04-01

    Vestibular paroxysmia due to neurovascular compression is a syndrome consisting of frequent short episodes of vertigo in adults that can be easily treated. Here we describe the initial presentation and follow-up of three children (one female, 12y; two males, 8y and 9y) who experienced typical, brief, vertiginous attacks several times a day. Nystagmus was observed during the episodes. Cranial magnetic resonance imaging revealed arterial compression of the eighth cranial nerve. The attacks ceased after administration of low-dose carbamazepine (2-4mg/kg daily). Vestibular paroxysmia must be considered in the differential diagnosis of children with brief vertiginous episodes. PMID:25146998

  5. The Vestibular System Michael E. Goldberg

    E-print Network

    Harris, Laurence R.

    , and invertebrates for still longer. The vestibular system is designed to answer two of the questions basic to human movements that stabilize retinal images despite head and body motions. #12;Figure 40-1 The vestibular acceleration about any axis. Linear accelerations, including those produced by gravity and those resulting from

  6. Vestibular-visual interactions in flight simulators

    NASA Technical Reports Server (NTRS)

    Clark, B.

    1977-01-01

    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.

  7. A Structure-Based Simulation Approach for Electron Paramagnetic Resonance Spectra Using Molecular and Stochastic

    E-print Network

    Steinhoff, Heinz-Jürgen

    -label specifically linked to a desired site within the protein. EPR spectra calculations based on molecular dynamics­3). Electron paramagnetic resonance (EPR) spectroscopy is a sensitive tool to detect molecular dynamics are detectable. In particular, EPR in combination with site-directed spin-labeling (4) is appropriate to study

  8. The role of cervical and ocular vestibular-evoked myogenic potentials in the follow-up of vestibular neuritis.

    PubMed

    Adamec, Ivan; Skori?, Magdalena Krbot; Handži?, Jadranka; Baruši?, Anabella Karla; Bach, Ivo; Gabeli?, Tereza; Habek, Mario

    2014-04-01

    This study evaluates the recovery of vestibular nerve function after vestibular neuritis (VN) by vestibular-evoked myogenic potentials (VEMPs). Twenty-six patients with the diagnosis of VN were included. All patients underwent ocular VEMP (oVEMP) and cervical VEMP (cVEMP) recordings, at 6 days and 6 months from the onset of the symptoms. Of the 26 patients, 14 showed improvement on oVEMP at month 6 (group 1), and 12 showed no change or worsening on oVEMP at 6 months (group 2). At the same time, there was no change in the amplitudes of the cVEMP on either healthy or affected sides in both groups. Inability to perform the Fukuda test, and chronic white matter supratentorial lesions present on brain magnetic resonance imaging (MRI) were more frequent in patients with worse outcome on oVEMP (P = 0.044 and 0.045, respectively). Although involvement of the inferior branch of the vestibular nerve was not associated with oVEMP outcome, oVEMP latencies (N10 and P13) were associated with improvement or worsening in oVEMP amplitudes, showing that prolonged latencies correlate with 6-month improvement in oVEMP amplitudes (Pearson correlation -0.472, P = 0.041 and -0.580, P = 0.009, respectively). This study identified clinical, MRI and neurophysiological predictors of recovery in patients with superior VN, and offers additional insight into, and better understanding of, the role of VEMP in diagnosis and prognosis of patients with VN. Further studies are needed to validate this diagnostic procedure and to assess its clinical usefulness in VN management. PMID:23666957

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

    PubMed Central

    Beier, Christian; Steinhoff, Heinz-Jürgen

    2006-01-01

    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 the motional freedom of the spin-label specifically linked to a desired site within the protein. EPR spectra calculations based on molecular dynamics (MD) and stochastic dynamics simulations facilitate verification or refinement of predicted computer-aided models of local protein conformations. The presented spectra simulation algorithm implies a specialized in vacuo MD simulation at 600 K with additional restrictions to sample the entire accessible space of the bound spin-label without large temporal effort. It is shown that the distribution of spin-label orientations obtained from such MD simulations at 600 K agrees well with the extrapolated motion behavior during a long timescale MD at 300 K with explicit water. The following potential-dependent stochastic dynamics simulation combines the MD data about the site-specific orientation probabilities of the spin-label with a realistic rotational diffusion coefficient yielding a set of trajectories, each more than 700 ns long, essential to calculate the EPR spectrum. Analyses of a structural model of the loop between helices E and F of bacteriorhodopsin are illustrated to demonstrate the applicability and potentials of the reported simulation approach. Furthermore, effects on the motional freedom of bound spin-labels induced by solubilization of bacteriorhodopsin with Triton X-100 are examined. PMID:16844740

  10. Significance of Vestibular Evoked Myogenic Potentials in Peripheral Vestibulopathy

    Microsoft Academic Search

    Hyun-Young Kim; Hee-Tae Kim; Seung-Hyun Kim; Juhan Kim; Myung-Ho Kim; Ki-Bum Sung

    Background : Loud monaural clicks evoke myogenic potentials in the tonically contracting ipsilateral sternocleido - mastoid muscle. Clinical studies have suggested that these myogenic potentials are of vestibular origin, especially infe - rior vestibular nerve. Neurophysiological experimental studies also suggest that they are most likely to be of saccular origin. These potentials are called vestibular evoked myogenic potentials (VEMPs). Vestibular

  11. The Application of Multiobjective Genetic Algorithm to the Parameter Optimization of Single-Well Potential Stochastic Resonance Algorithm Aimed at Simultaneous Determination of Multiple Weak Chromatographic Peaks

    PubMed Central

    Xiang, Bingren; Wu, Xiaohong; Liu, Dan

    2014-01-01

    Simultaneous determination of multiple weak chromatographic peaks via stochastic resonance algorithm attracts much attention in recent years. However, the optimization of the parameters is complicated and time consuming, although the single-well potential stochastic resonance algorithm (SSRA) has already reduced the number of parameters to only one and simplified the process significantly. Even worse, it is often difficult to keep amplified peaks with beautiful peak shape. Therefore, multiobjective genetic algorithm was employed to optimize the parameter of SSRA for multiple optimization objectives (i.e., S/N and peak shape) and multiple chromatographic peaks. The applicability of the proposed method was evaluated with an experimental data set of Sudan dyes, and the results showed an excellent quantitative relationship between different concentrations and responses. PMID:24526920

  12. The application of multiobjective genetic algorithm to the parameter optimization of single-well potential stochastic resonance algorithm aimed at simultaneous determination of multiple weak chromatographic peaks.

    PubMed

    Deng, Haishan; Xie, Shaofei; Xiang, Bingren; Zhan, Ying; Li, Wei; Li, Xiaohua; Jiang, Caiyun; Wu, Xiaohong; Liu, Dan

    2014-01-01

    Simultaneous determination of multiple weak chromatographic peaks via stochastic resonance algorithm attracts much attention in recent years. However, the optimization of the parameters is complicated and time consuming, although the single-well potential stochastic resonance algorithm (SSRA) has already reduced the number of parameters to only one and simplified the process significantly. Even worse, it is often difficult to keep amplified peaks with beautiful peak shape. Therefore, multiobjective genetic algorithm was employed to optimize the parameter of SSRA for multiple optimization objectives (i.e., S/N and peak shape) and multiple chromatographic peaks. The applicability of the proposed method was evaluated with an experimental data set of Sudan dyes, and the results showed an excellent quantitative relationship between different concentrations and responses. PMID:24526920

  13. Cooperative effects of inherent stochasticity and random long-range connections on synchronization and coherence resonance in diffusively coupled calcium oscillators

    NASA Astrophysics Data System (ADS)

    Wang, Maosheng; Sun, Runzhi

    2014-03-01

    The cooperative effects of inherent stochasticity and random long-range connections (RLRCs) on synchronization and coherence resonance in networks of calcium oscillators have been investigated. Two different types of collective behaviors, coherence resonance (CR) and synchronization, have been studied numerically in the context of chemical Langevin equations (CLEs). In the CLEs, the reaction steps are all stochastic, including the exchange of calcium ions between adjacent and non-adjacent cells through the gap junctions. The calcium oscillators’ synchronization was characterized by the standard deviation of the cytosolic calcium concentrations. Meanwhile, the temporal coherence of the calcium spike train was characterized by the reciprocal coefficient of variance (RCV). Synchronization induced by RLRCs was observed, namely, the exchange of calcium ions between non-adjacent cells can promote the synchronization of the cells. Moreover, it was found that the RCV shows a clear peak when both inherent stochasticity and RLRCs are optimal, indicating the existence of CR. Since inherent stochasticity and RLRCs are two essential ingredients of cellular processes, synchronization and CR are also important for cells’ functions. The results reported in this paper are expected to be useful for understanding the dynamics of intercellular calcium signaling processes in vivo.

  14. Enhancement of information transmission of sub-threshold signals applied to distal positions of dendritic trees in hippocampal CA1 neuron models with stochastic resonance

    Microsoft Academic Search

    Hiroyuki Mino; Dominique M. Durand

    2010-01-01

    Stochastic resonance (SR) has been shown to enhance the signal-to-noise ratio and detection of low level signals in neurons.\\u000a It is not yet clear how this effect of SR plays an important role in the information processing of neural networks. The objective\\u000a of this article is to test the hypothesis that information transmission can be enhanced with SR when sub-threshold

  15. Double stochastic resonance in the mean-field q-state clock model

    NASA Astrophysics Data System (ADS)

    Baek, Seung Ki; Kim, Beom Jun

    2012-07-01

    A magnetic system with a phase transition at temperature Tc may exhibit double-resonance peaks under a periodic external magnetic field because the time scale matches the external frequency at two different temperatures, one above Tc and the other below Tc. We study the double-resonance phenomena for the mean-field q-state clock model based on the heat-bath-type master equation. We find double peaks as observed in the kinetic Ising case (q=2) for all q?4, but for the three-state clock model (q=3), the existence of double peaks is possible only above a certain external frequency since it undergoes a discontinuous phase transition.

  16. Double stochastic resonance in the mean-field q-state clock model.

    PubMed

    Baek, Seung Ki; Kim, Beom Jun

    2012-07-01

    A magnetic system with a phase transition at temperature T(c) may exhibit double-resonance peaks under a periodic external magnetic field because the time scale matches the external frequency at two different temperatures, one above T(c) and the other below T(c). We study the double-resonance phenomena for the mean-field q-state clock model based on the heat-bath-type master equation. We find double peaks as observed in the kinetic Ising case (q = 2) for all q ? 4, but for the three-state clock model (q = 3), the existence of double peaks is possible only above a certain external frequency since it undergoes a discontinuous phase transition. PMID:23005393

  17. Stochastic transport modeling of resonant magnetic perturbations in DIII-D

    Microsoft Academic Search

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

    2007-01-01

    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

  18. Stochastic Transport Modeling of Resonant Magnetic Perturbations in DIII-D

    Microsoft Academic Search

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

    2006-01-01

    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

  19. On the evolution of mean motion resonances through stochastic forcing: Fast and slow libration modes and the origin of HD128311

    E-print Network

    Hanno Rein; John C. B. Papaloizou

    2009-02-12

    Aims. We clarify the response of extrasolar planetary systems in a 2:1 mean motion commensurability with masses ranging from the super Jovian range to the terrestrial range to stochastic forcing that could result from protoplanetary disk turbulence. The behaviour of the different libration modes for a wide range of system parameters and stochastic forcing magnitudes is investigated. The growth of libration amplitudes is parameterized as a function of the relevant physical parameters. The results are applied to provide an explanation of the configuration of the HD128311 system. Methods. We first develop an analytic model from first principles without making the assumption that both eccentricities are small. We also perform numerical N-body simulations with additional stochastic forcing terms to represent the effects of putative disk turbulence. Results. Systems are quickly destabilized by large magnitudes of stochastic forcing but some stability is imparted should systems undergo a net orbital migration. The slow mode, which mostly corresponds to motion of the angle between the apsidal lines of the two planets, is converted to circulation more readily than the fast mode which is associated with oscillations of the semi-major axes. This mode is also vulnerable to the attainment of small eccentricities which causes oscillations between periods of libration and circulation. Conclusions. Stochastic forcing due to disk turbulence may have played a role in shaping the configurations of observed systems in mean motion resonance. It naturally provides a mechanism for accounting for the HD128311 system.

  20. Resonant control of stochastic spatiotemporal dynamics in a tunnel diode by multiple time-delayed feedback.

    PubMed

    Majer, Niels; Schöll, Eckehard

    2009-01-01

    We study the control of noise-induced spatiotemporal current density patterns in a semiconductor nanostructure (double-barrier resonant tunneling diode) by multiple time-delayed feedback. We find much more pronounced resonant features of noise-induced oscillations compared to single time feedback, rendering the system more sensitive to variations in the delay time tau . The coherence of noise-induced oscillations measured by the correlation time exhibits sharp resonances as a function of tau , and can be strongly increased by optimal choices of tau . Similarly, the peaks in the power spectral density are sharpened. We provide analytical insight into the control mechanism by relating the correlation times and mean frequencies of noise-induced breathing oscillations to the stability properties of the deterministic stationary current density filaments under the influence of the control loop. Moreover, we demonstrate that the use of multiple time delays enlarges the regime in which the deterministic dynamical properties of the system are not changed by delay-induced bifurcations. PMID:19257003

  1. Resonant control of stochastic spatiotemporal dynamics in a tunnel diode by multiple time-delayed feedback

    NASA Astrophysics Data System (ADS)

    Majer, Niels; Schöll, Eckehard

    2009-01-01

    We study the control of noise-induced spatiotemporal current density patterns in a semiconductor nanostructure (double-barrier resonant tunneling diode) by multiple time-delayed feedback. We find much more pronounced resonant features of noise-induced oscillations compared to single time feedback, rendering the system more sensitive to variations in the delay time ? . The coherence of noise-induced oscillations measured by the correlation time exhibits sharp resonances as a function of ? , and can be strongly increased by optimal choices of ? . Similarly, the peaks in the power spectral density are sharpened. We provide analytical insight into the control mechanism by relating the correlation times and mean frequencies of noise-induced breathing oscillations to the stability properties of the deterministic stationary current density filaments under the influence of the control loop. Moreover, we demonstrate that the use of multiple time delays enlarges the regime in which the deterministic dynamical properties of the system are not changed by delay-induced bifurcations.

  2. 7-Tesla MRI demonstrates absence of structural lesions in patients with vestibular paroxysmia

    PubMed Central

    Rommer, Paulus S.; Wiest, Gerald; Kronnerwetter, Claudia; Zach, Heidemarie; Loader, Benjamin; Elwischger, Kirsten; Trattnig, Siegfried

    2015-01-01

    Vestibular parxoysmia (VP) is a rare vestibular disorder. A neurovascular cross-compression (NVCC) between the vestibulochochlear nerve and an artery seems to be responsible for short attacks of vertigo in this entity. An NVCC can be seen in up to every fourth subject. The significance of these findings is not clear, as not all subjects suffer from symptoms. The aim of the present study was to assess possible structural lesions of the vestibulocochlear nerve by means of high field magnetic resonance imaging (MRI), and whether high field MRI may help to differentiate symptomatic from asymptomatic subjects. 7 Tesla MRI was performed in six patients with VP and confirmed NVCC seen on 1.5 and 3.0 MRI. No structural abnormalities were detected in any of the patients in 7 Tesla MRI. These findings imply that high field MRI does not help to differentiate between symptomatic and asymptomatic NVCC and that the symptoms of VP are not caused by structural nerve lesions. This supports the hypothesis that the nystagmus associated with VP has to be conceived pathophysiologically as an excitatory vestibular phenomenon, being not related to vestibular hypofunction. 7 Tesla MRI outperforms conventional MRI in image resolution and may be useful in vestibular disorders. PMID:26106306

  3. Stochastic resonance and dynamic first-order pseudo-phase-transitions in the irreversible growth of thin films under spatially periodic magnetic fields.

    PubMed

    Loscar, Ernesto S; Candia, Julián

    2013-10-01

    We study the irreversible growth of magnetic thin films under the influence of spatially periodic fields by means of extensive Monte Carlo simulations. We find first-order pseudo-phase-transitions that separate a dynamically disordered phase from a dynamically ordered phase. By analogy with time-dependent oscillating fields applied to Ising-type models, we qualitatively associate this dynamic transition with the localization-delocalization transition of spatial hysteresis loops. Depending on the relative width of the magnetic film L compared to the wavelength of the external field ?, different transition regimes are observed. For small systems (L < ?), the transition is associated with the standard stochastic resonance regime, while for large systems (L > ?), the transition is driven by anomalous stochastic resonance. The origin of the latter is identified as due to the emergence of an additional relevant length scale, namely, the roughness of the spin domain switching interface. The distinction between different stochastic resonance regimes is discussed at length both qualitatively by means of snapshot configurations and quantitatively via residence-length and order-parameter probability distributions. PMID:24229194

  4. Dara vestibular equipment onboard MIR

    NASA Astrophysics Data System (ADS)

    Hofmann, P.; Kellig, A.; Hoffmann, H.-U.; Ruyters, G.

    We have described the vestibular and visuo-oculomotoric equipment which has been developed under various DARA contracts since 1991, and used aboard MIR in the frame of the following missions: • German MIR'92 mission (VOG) • Extensions to MIR '92, e.g. the use of VOG by V. Polyakov during his record stay in space from 1993 to 1994 • EUROMIR'94 (VOG) • EUROMIR'95 (VOG, OKS and BIVOG) • Joint German /Russian experiments in 1997/98 (BIVOG) The hardware is supplemented by various stimuli and measurements. New developments for a next generation BIVOG, which may become the Space Station 3D eye tracking system, have shortly been addressed.

  5. Stochastic resonance with a mixture of sub-and supra-threshold stimuli in a population of neuron models.

    PubMed

    Kawaguchi, Minato; Mino, Hiroyuki; Momose, Keiko; Durand, Dominique M

    2011-01-01

    This paper presents a novel type of stochastic resonance (SR) with a mixture of sub- and supra-threshold stimuli in a population of neuron models beyond regular SR and Supra-threshold SR (SSR) phenomena. We investigate through computer simulations if the novel type of SR can be observed or not, using the mutual information (MI) estimated from a population of neural spike trains as an index of information transmission. Computer simulations showed that the MI had a typical type of SR curves, even when the balance between sub-and supra-threshold stimuli was varied, suggesting the novel type of SR. Moreover, the peak of MI increased as the balance of supra-threshold stimuli got stronger, i.e., as the situation was getting close to the SSR from the regular SR. This finding could accelerate our understanding about how fluctuations play a role in processing information carried by a mixture of sub-and supra-threshold stimuli. PMID:22256031

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

    NASA Astrophysics Data System (ADS)

    Aragie, Berhanu

    2014-10-01

    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)].

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

    PubMed

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

    2014-01-01

    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

  8. Stochastic approach to diffusion inside the chaotic layer of a resonance.

    PubMed

    Mestre, Martín F; Bazzani, Armando; Cincotta, Pablo M; Giordano, Claudia M

    2014-01-01

    We model chaotic diffusion in a symplectic four-dimensional (4D) map by using the result of a theorem that was developed for stochastically perturbed integrable Hamiltonian systems. We explicitly consider a map defined by a free rotator (FR) coupled to a standard map (SM). We focus on the diffusion process in the action I of the FR, obtaining a seminumerical method to compute the diffusion coefficient. We study two cases corresponding to a thick and a thin chaotic layer in the SM phase space and we discuss a related conjecture stated in the past. In the first case, the numerically computed probability density function for the action I is well interpolated by the solution of a Fokker-Planck (FP) equation, whereas it presents a nonconstant time shift with respect to the concomitant FP solution in the second case suggesting the presence of an anomalous diffusion time scale. The explicit calculation of a diffusion coefficient for a 4D symplectic map can be useful to understand the slow diffusion observed in celestial mechanics and accelerator physics. PMID:24580301

  9. Stochastic approach to diffusion inside the chaotic layer of a resonance

    NASA Astrophysics Data System (ADS)

    Mestre, Martín F.; Bazzani, Armando; Cincotta, Pablo M.; Giordano, Claudia M.

    2014-01-01

    We model chaotic diffusion in a symplectic four-dimensional (4D) map by using the result of a theorem that was developed for stochastically perturbed integrable Hamiltonian systems. We explicitly consider a map defined by a free rotator (FR) coupled to a standard map (SM). We focus on the diffusion process in the action I of the FR, obtaining a seminumerical method to compute the diffusion coefficient. We study two cases corresponding to a thick and a thin chaotic layer in the SM phase space and we discuss a related conjecture stated in the past. In the first case, the numerically computed probability density function for the action I is well interpolated by the solution of a Fokker-Planck (FP) equation, whereas it presents a nonconstant time shift with respect to the concomitant FP solution in the second case suggesting the presence of an anomalous diffusion time scale. The explicit calculation of a diffusion coefficient for a 4D symplectic map can be useful to understand the slow diffusion observed in celestial mechanics and accelerator physics.

  10. Vestibular stimulation modifies the body schema.

    PubMed

    Lopez, Christophe; Schreyer, Helene-Marianne; Preuss, Nora; Mast, Fred W

    2012-07-01

    Mental body representations are flexible and depend on sensory signals from the body and its surrounding. Clinical observations in amputees, paraplegics and brain-damaged patients suggest a vestibular contribution to the body schema, but studies using well-controlled psychophysical procedures are still lacking. In Experiment 1, we used a tactile distance comparison task between two body segments (hand and forehead). The results showed that objects contacting the hand were judged longer during caloric vestibular stimulation when compared to control thermal stimulation. In Experiment 2, participants located four anatomical landmarks on their left hand by pointing with their right hand. The perceived length and width of the left hand increased during caloric vestibular stimulation with respect to a control stimulation. The results show that the body schema temporarily adjusts as a function of vestibular signals, modifying the internal representation of the hand size. The data provide evidence that vestibular functions are not limited to postural and oculomotor control, and extend the contribution of the vestibular system to bodily cognition. The findings from this study suggest the inclusion of vestibular signals into current models of body representations and bodily self-consciousness. PMID:22561888

  11. Genetic disorders of the vestibular system

    PubMed Central

    Eppsteiner, Robert W.; Smith, Richard J.H.

    2012-01-01

    Purpose of review This review highlights the current body of literature related to the genetics of inherited vestibular disorders and provides a framework for the characterization of these disorders. We emphasize peripheral causes of vestibular dysfunction and highlight recent advances in the field, point out gaps in understanding, and focus on key areas for future investigation. Recent findings The discovery of a modifier gene that leads to a more severe Usher syndrome phenotype calls into question the assumption that Usher syndrome is universally a monogenic disorder. Despite the use of several investigational approaches, the genetic basis of Menière’s disease remains poorly understood. Evidence for a vestibular phenotype associated with DFNB1 suggests that mutations in other genes causally related to nonsyndromic hearing loss also may have an unrecognized vestibular phenotype. Summary Our understanding of the genetic basis for vestibular disorders is superficial. Significant challenges include defining the genetics of inherited isolated vestibular dysfunction and understanding the pathological basis of Menière’s disease. However, improved characterization of inherited vestibular dysfunction, coupled with advanced genetic techniques such as targeted genome capture and massively parallel sequencing, provides an opportunity to investigate these diseases at the genetic level. PMID:21825995

  12. The velocity response of vestibular nucleus neurons during vestibular, visual, and combined angular acceleration

    Microsoft Academic Search

    W. Waespe; V. Henn

    1979-01-01

    In alert Rhesus monkeys neuronal activity in the vestibular nuclei was measured during horizontal angular acceleration in darkness, acceleration of an optokinetic stimulus, and combined visual-vestibular stimulation. The working ranges for visual input velocity and acceleration extend up to 60 °\\/s and 5 °\\/s2. The corresponding working range for vestibular input acceleration is wider and time-dependent. During combined stimulation, that

  13. The Anatomical and Physiological Framework for Vestibular Prostheses

    PubMed Central

    Highstein, Stephen M.; Holstein, Gay R.

    2014-01-01

    This article reviews the structure function of the vestibular system and its pathology with respect to requirements for the design and construction of a functional vestibular prosthesis. The ultimate goal of a vestibular prosthesis is to restore balance and equilibrium through direct activation of vestibular nerve fibers. An overview of the peripheral and central vestibular systems that highlights their most important functional aspects re: the design of a prosthesis is provided. Namely, the peripheral labyrinth faithfully transduces head motion and gravity in both the time and frequency domains. These signals are described in hopes that they may be prosthetically replicated. The peripheral and central connections of the vestibular nerve are also discussed in detail, as are the vestibular nuclei in the brainstem that receive VIIIth nerve innervation. Lastly, the functional effector pathways of the vestibular system, including the vestibulo-ocular, vestibulo-spinal, vestibulo-colic, vestibulo-autonomic, and vestibular efferent innervation of the labyrinth are reviewed. PMID:23044714

  14. Enlarged Vestibular Aqueducts and Childhood Hearing Loss

    MedlinePLUS

    ... and disordered processes of hearing, balance, taste, smell, voice, speech, and language. Use the following keywords to help you search for organizations that are relevant to enlarged vestibular aqueducts: Early identification of deafness in children Genetic diseases/disorders For ...

  15. [Vestibular schwannoma: a case report of misdiagnosis].

    PubMed

    You, Huizeng; Li, Xiaoying; Wang, Wuqing

    2014-11-01

    Vestibular schwannoma is a rare tumor, which is easily misdiagnosed. The authors presented a case of vestibular schwannoma in a 36-year-old woman. The clinical manifestations were recurrent vertigo, hearing loss of the left ear, and tinnitus. The pure tone audiometry threshold of the left ear was 45dBHL with air conduction, and 33 dBHL with bone conduction. A CT scan of the temporal bone region didn't show any abnormal finding. A MRI scan of the head showed nodule abnormal signal in the internal of left vestibular and the narrow of perilymphaticum gap in T2W1 + T2Flair. The initial diagnosis was Meniere's disease. And the post-operation pathologic diagnosis was vestibular schwannoma. PMID:25752127

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

    PubMed

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

    2014-12-01

    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 (~77 years) and eight young (~26 years) 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 (0-25 Hz, root mean square amplitude=0.85 mA). 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

  17. Vestibular and Saccadic Abnormalities in Gaucher's Disease.

    PubMed

    Chen, Luke; Halmagyi, G Michael; Todd, Michael J; Aw, Swee T

    2014-01-01

    Gaucher's disease (GD) is a hereditary lysosomal storage disease characterized by abnormal deposition of glucocerebroside due to the enzyme glucocerebrosidase deficiency, resulting in multi-organ pathology. GD type III has a progressive neurological involvement. We studied the vestibular and saccadic abnormalities in GD type III to determine if these parameters may be useful for assessing neurological involvement. We evaluated the vestibular and saccadic responses of two siblings with genetically identified GD type III on enzyme replacement therapy. Vestibular functions were assessed with the head impulse test (HIT), vestibular evoked myogenic potentials (VEMPs), and electrical vestibular stimulation (EVS). Saccadic functions were investigated with volitional horizontal and vertical saccades to ±20°. Three-dimensional head and eye movements were recorded with dual-search coils and VEMP with surface electrodes. HIT showed impaired individual semicircular canal function with halved angular vestibulo-ocular reflex (VOR) gains and absent horizontal refixation saccade. Ocular and cervical VEMPs to air-conducted clicks were absent in the older sibling, and only cervical VEMP was present in the younger sibling indicating otolithic dysfunction. EVS showed prolonged onset latency and attenuated tonic and phasic responses suggesting impaired neural conduction and vestibular function. Horizontal saccadic velocity was miniscule (<30°/s) and multiple back-to-back saccades with saccade-vergence interaction were utilized to minimize eye position error in the older sibling. Vertical saccades were slightly abnormal, but vergence and smooth pursuit were normal in both siblings. Our findings suggest that GD affected the vestibular nuclei in addition to the paramedian pontine reticular formation. These vestibular and saccadic abnormalities may be useful biomarkers to monitor neurological deterioration. PMID:24142279

  18. Vestibular function assessment using the NIH Toolbox

    PubMed Central

    Schubert, Michael C.; Whitney, Susan L.; Roberts, Dale; Redfern, Mark S.; Musolino, Mark C.; Roche, Jennica L.; Steed, Daniel P.; Corbin, Bree; Lin, Chia-Cheng; Marchetti, Greg F.; Beaumont, Jennifer; Carey, John P.; Shepard, Neil P.; Jacobson, Gary P.; Wrisley, Diane M.; Hoffman, Howard J.; Furman, Gabriel; Slotkin, Jerry

    2013-01-01

    Objective: Development of an easy to administer, low-cost test of vestibular function. Methods: Members of the NIH Toolbox Sensory Domain Vestibular, Vision, and Motor subdomain teams collaborated to identify 2 tests: 1) Dynamic Visual Acuity (DVA), and 2) the Balance Accelerometry Measure (BAM). Extensive work was completed to identify and develop appropriate software and hardware. More than 300 subjects between the ages of 3 and 85 years, with and without vestibular dysfunction, were recruited and tested. Currently accepted gold standard measures of static visual acuity, vestibular function, dynamic visual acuity, and balance were performed to determine validity. Repeat testing was performed to examine reliability. Results: The DVA and BAM tests are affordable and appropriate for use for individuals 3 through 85 years of age. The DVA had fair to good reliability (0.41–0.94) and sensitivity and specificity (50%–73%), depending on age and optotype chosen. The BAM test was moderately correlated with center of pressure (r = 0.42–0.48) and dynamic posturography (r = ?0.48), depending on age and test condition. Both tests differentiated those with and without vestibular impairment and the young from the old. Each test was reliable. Conclusion: The newly created DVA test provides a valid measure of visual acuity with the head still and moving quickly. The novel BAM is a valid measure of balance. Both tests are sensitive to age-related changes and are able to screen for impairment of the vestibular system. PMID:23479540

  19. [Vestibular neuronitis: pathophysiology, diagnosis and treatment].

    PubMed

    Zaper, Dinka; Adamec, Ivan; Gabeli?, Tereza; Krbot, Magdalena; Isgum, Velimir; Hajnsek, Sanja; Habek, Mario

    2012-01-01

    Vestibular neuritis (VN) is one of the most common causes of peripheral vertigo. Caloric testing has been the traditional gold standard for detecting a peripheral vestibular deficit, but some recently developed bedside tests (head thrust, head heave, head shake and vibration test) were evaluated as a good alternative with similar sensitivity and specificity. These tests have shown both diagnostic value in the short term and prognostic value in the long term, and have availability and ease of use as an advantage. As an addition to clinical examination, vestibular evoked myogenic potentials can differentiate between involvement of superior and inferior branch of the vestibular nerve, but also between peripheral and central lesions. Although glucocorticoids are currently widely used in the treatment of VN, there is a lack of evidence for the validity of their administration. There are a number of high quality clinical trials that suggest vestibular rehabilitation exercises, which are based on the mechanisms of vestibular compensation, in the managment of VN. This review will focus on the latest developments in the pathophysiology, diagnosis and treatment of patients with VN. PMID:23401980

  20. Landscape, Flux, Correlation, Resonance, Coherence, Stability, and Key Network Wirings of Stochastic Circadian Oscillation

    PubMed Central

    Li, Chunhe; Wang, Erkang; Wang, Jin

    2011-01-01

    Circadian rhythms with a period of ?24 h, are natural timing machines. They are broadly distributed in living organisms, such as Neurospora, Drosophila, and mammals. The underlying natures of the rhythmic behavior have been explored by experimental and theoretical approaches. However, the global and physical natures of the oscillation under fluctuations are still not very clear. We developed a landscape and flux framework to explore the global stability and robustness of a circadian oscillation system. The potential landscape of the network is uncovered and has a global Mexican-hat shape. The height of the Mexican-hat provides a quantitative measure to evaluate the robustness and coherence of the oscillation. We found that in nonequilibrium dynamic systems, not only the potential landscape but also the probability flux are important to the dynamics of the system under intrinsic noise. Landscape attracts the systems down to the oscillation ring while flux drives the coherent oscillation on the ring. We also investigated the phase coherence and the entropy production rate of the system at different fluctuations and found that dissipations are less and the coherence is higher for larger number of molecules. We also found that the power spectrum of autocorrelation functions show resonance peak at the frequency of coherent oscillations. The peak is less prominent for smaller number of molecules and less barrier height and therefore can be used as another measure of stability of oscillations. As a consequence of nonzero probability flux, we show that the three-point correlations from the time traces show irreversibility, providing a possible way to explore the flux from the observations. Furthermore, we explored the escape time from the oscillation ring to outside at different molecular number. We found that when barrier height is higher, escape time is longer and phase coherence of oscillation is higher. Finally, we performed the global sensitivity analysis of the underlying parameters to find the key network wirings responsible for the stability of the oscillation system. PMID:21943414

  1. Top-down approach to vestibular compensation: translational lessons from vestibular rehabilitation

    PubMed Central

    Balaban, Carey D.; Hoffer, Michael E.; Gottshall, Kim R.

    2012-01-01

    This review examines vestibular compensation and vestibular rehabilitation from a unified translational research perspective. Laboratory studies illustrate neurobiological principles of vestibular compensation at the molecular, cellular and systems levels in animal models that inform vestibular rehabilitation practice. However, basic research has been hampered by an emphasis on ‘naturalistic’ recovery, with time after insult and drug interventions as primary dependent variables. The vestibular rehabilitation literature, on the other hand, provides information on how the degree of compensation can be shaped by specific activity regimens. The milestones of the early spontaneous static compensation mark the re-establishment of static gaze stability, which provides a common coordinate frame for the brain to interpret residual vestibular information in the context of visual, somatosensory and visceral signals that convey gravitoinertial information. Stabilization of the head orientation and the eye orientation (suppression of spontaneous nystagmus) appear to be necessary by not sufficient conditions for successful rehabilitation, and define a baseline for initiating retraining. The lessons from vestibular rehabilitation in animal models offer the possibility of shaping the recovery trajectory to identify molecular and genetic factors that can improve vestibular compensation. PMID:22981400

  2. Vestibular cues and virtual environments: choosing the magnitude of the vestibular cue

    E-print Network

    Harris, Laurence R.

    perceived magnitude of motion. The model suggests that designers of virtual reality displays should addVestibular cues and virtual environments: choosing the magnitude of the vestibular cue Laurence , and Biology3 York University 4700 Keele St., Toronto, Ontario, Canada, M3J 1P3 Abstract The design of virtual

  3. Vestibular Dysfunction in DFNB1 deafness

    PubMed Central

    Dodson, Kelley M; Blanton, Susan H; Welch, Katherine O; Norris, Virginia W; Nuzzo, Regina L; Wegelin, Jacob A.; Marin, Ruth S; Nance, Walter E; Pandya, Arti; Arnos, Kathleen S

    2010-01-01

    Mutations of GJB2 and GJB6 (connexin-26 and 30) at the DFNB1 locus are the most common cause of autosomal recessive, nonsyndromic deafness. Despite their widespread expression throughout the vestibular system, vestibular dysfunction has not been widely recognized as a commonly associated clinical feature. The observations of vertigo accompanying DFNB1 deafness in several large families prompted our hypothesis that vestibular dysfunction may be an integral, but often overlooked, component of DFNB1 deafness. Our aim was to define the prevalence of vestibular dysfunction in Cases of DFNB1 deafness and Controls with other forms of deafness. We developed and used a survey to assess symptoms of vestibular dysfunction, medical, and family history was distributed to Cases with deafness due to pathogenic GJB2 and/or GJB6 mutations and deaf Controls without DFNB1 deafness. Our results showed: Surveys were returned by 235/515 Cases (46%) with DFNB1 mutations and 121/ 321 Controls (38%) without these mutations. The mean age of Cases (41) was younger than Controls (51; p<0.001). Vestibular dysfunction was reported by 127 (54%) of Cases and was present at significantly higher rates in Cases than in deaf Controls without DFNB1 deafness (p< 0.03). Most (63%) had to lie down in order for vertigo to subside, and 48% reported that vertigo interfered with activities of daily living. Vertigo was reported by significantly more Cases with truncating than non-truncating mutations and was also associated with a family history of dizziness. We conclude that vestibular dysfunction appears to be more common in DFNB1 deafness than previously recognized and affects activities of daily living in many patients. PMID:21465647

  4. Windowed Stochastic Proton Decoupling for in Vivo 13C Magnetic Resonance Spectroscopy with Reduced RF Power Deposition

    PubMed Central

    Xiang, Yun; Shen, Jun

    2011-01-01

    Purpose To propose a strategy for reducing RF power deposition by stochastic proton decoupling based on Rayleigh’s theorem. Materials and Methods Rayleigh’s theorem was used to remove frequency components of stochastic decoupling over the 3.90–6.83 ppm range. [2-13C] or [2,5-13C2]glucose was infused intravenously to anesthetized rats. 13C labeling of brain metabolites was detected in the carboxylic/amide spectral region at 11.7 Tesla using either the original stochastic decoupling method developed by Ernst or the proposed windowed stochastic decoupling method. Results By restricting frequency components of stochastic decoupling to 1.91–3.90 ppm and 6.83–7.60 ppm spectral regions decoupling power deposition was reduced by ~50%. The proposed windowed stochastic decoupling scheme is experimentally demonstrated for in vivo 13C MRS of rat brain at 11.7 Tesla. Conclusion The large reduction in decoupling power deposition makes it feasible to perform stochastic proton decoupling at very high magnetic fields for human brain 13C MRS studies. PMID:21769967

  5. Auditory and Vestibular Issues Related to Human Spaceflight

    NASA Technical Reports Server (NTRS)

    Danielson, Richard W.; Wood, Scott J.

    2009-01-01

    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.

  6. Computational Approaches to Vestibular Research

    NASA Technical Reports Server (NTRS)

    Ross, Muriel D.; Wade, Charles E. (Technical Monitor)

    1994-01-01

    The Biocomputation Center at NASA Ames Research Center is dedicated to a union between computational, experimental and theoretical approaches to the study of neuroscience and of life sciences in general. The current emphasis is on computer reconstruction and visualization of vestibular macular architecture in three-dimensions (3-D), and on mathematical modeling and computer simulation of neural activity in the functioning system. Our methods are being used to interpret the influence of spaceflight on mammalian vestibular maculas in a model system, that of the adult Sprague-Dawley rat. More than twenty 3-D reconstructions of type I and type II hair cells and their afferents have been completed by digitization of contours traced from serial sections photographed in a transmission electron microscope. This labor-intensive method has now been replace d by a semiautomated method developed in the Biocomputation Center in which conventional photography is eliminated. All viewing, storage and manipulation of original data is done using Silicon Graphics workstations. Recent improvements to the software include a new mesh generation method for connecting contours. This method will permit the investigator to describe any surface, regardless of complexity, including highly branched structures such as are routinely found in neurons. This same mesh can be used for 3-D, finite volume simulation of synapse activation and voltage spread on neuronal surfaces visualized via the reconstruction process. These simulations help the investigator interpret the relationship between neuroarchitecture and physiology, and are of assistance in determining which experiments will best test theoretical interpretations. Data are also used to develop abstract, 3-D models that dynamically display neuronal activity ongoing in the system. Finally, the same data can be used to visualize the neural tissue in a virtual environment. Our exhibit will depict capabilities of our computational approaches and some of our findings from their application. For example, our research has demonstrated that maculas of adult mammals retain the property of synaptic plasticity. Ribbon synapses increase numerically and undergo changes in type and distribution (p<0.0001) in type II hair cells after exposure to microgravity for as few as nine days. The finding of macular synaptic plasticity is pertinent to the clinic, and may help explain some. balance disorders in humans. The software used in our investigations will be demonstrated for those interested in applying it in their own research.

  7. Topographical correlations of lateral medullary infarction with caloric and vestibular-evoked myogenic potential results

    Microsoft Academic Search

    Chih-Lung Tseng; Yi-Ho Young

    2010-01-01

    This study investigated the correlation of caloric- and vestibular-evoked myogenic potential (VEMP) results with topographical\\u000a lesions of lateral medullary infarction. Five patients with lateral medullary infarction were enrolled in this study. Each\\u000a patient underwent a battery of tests, including audiometry, caloric test, VEMP test, and magnetic resonance imaging (MRI)\\u000a study. Gaze nystagmus was observed in four patients (80%), while abnormal

  8. Intrinsic excitability changes in vestibular nucleus neurons after unilateral deafferentation

    Microsoft Academic Search

    A Him; M. B Dutia

    2001-01-01

    Two synergistic plastic mechanisms have recently been identified in rat medial vestibular nucleus (MVN) neurons during ‘vestibular compensation’, the behavioral recovery that follows damage to the vestibular receptors or nerve of one inner ear. Ipsi-lesional MVN neurons develop a significant increase in their intrinsic excitability, and a marked decrease in the functional efficacy of GABAA and GABAB receptors, within 4

  9. Alinhamento da cabeça de pacientes com hipofunção vestibular periférica unilateral submetidos à fisioterapia aquática para reabilitação vestibular Head alignment on patients with unilateral vestibular hypofunction submitted to aquatic physiotherapy for vestibular rehabilitation

    Microsoft Academic Search

    Yeda Pereira; Lima Gabilan; Karen Renate Mazzetti; Adamar Nunes; Juliana Maria Gazzola; Monica Rodrigues Perracini; Fernando Freitas Ganança

    AIM: To verify the effect of the aquatic physiotherapy protocol for vestibular rehabilitation (APVR) upon the head alignment of patients with unilateral peripheral vestibular hypofunction through computerized biophotogrammetry (CB), and to verify the association between those effects and the variables sex and age. METHOD: Experimental study with a sample of 21 patients with unilateral peripheral vestibular hypofunction, ranging in age

  10. Properties of rectified averaging of an evoked-type signal: theory and application to the vestibular-evoked myogenic potential

    Microsoft Academic Search

    J. G. Colebatch

    2009-01-01

    The properties of rectified averages were investigated using the VEMP (vestibular-evoked myogenic potential) as an example\\u000a of an evoked-type response. Recordings were made of surface EMG from the sternocleidomastoid (SCM) muscles of six volunteers,\\u000a unstimulated, at different levels of tonic activation and then in response to clicks of different intensities. The stochastic\\u000a properties of the surface EMG recorded were shown

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

    PubMed Central

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

    2007-01-01

    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

  12. Projections from the parabrachial nucleus to the vestibular nuclei: potential substrates for autonomic and limbic influences on vestibular responses

    Microsoft Academic Search

    Carey D Balaban

    2004-01-01

    Previous anatomical studies in rabbits and rats have shown that the superior vestibular nucleus (SVN), medial vestibular nucleus (MVN) and inferior vestibular nucleus (IVN) project to the parabrachial nucleus (PBN) and Kölliker–Fuse (KF) nucleus. Adult male albino rabbits and Long–Evans rats received iontophoretic injections of biotinylated dextran amine, Phaseolus vulgaris leucoagglutinin, Fluoro-Gold or tetramethylrhodamine dextran amine into either the vestibular

  13. Severe vestibular dysfunction and altered vestibular innervation in mice lacking prosaposin.

    PubMed

    Akil, Omar; Lustig, Lawrence R

    2012-04-01

    Prosaposin, a precursor of four glycoprotein activators (saposin A, B, C and D) for lysosomal hydrolases, has previously been shown to be important for normal adult cochlear innervation and the maintenance of normal hearing. In these studies, we now investigate prosaposin in normal vestibular epithelium and the functional impairment of balance caused by prosaposin ablation. In normal mice, prosaposin is localized to all 3 vestibular end-organs (ampullae, saccule, and utricle) and Scarpa's ganglion by RT-PCR, Western blot analysis and immunofluorescence. Ablation of prosaposin function caused severe vestibular dysfunction on a battery of behavioral tasks. Histologically, the KO mice demonstrated an exuberant cellular proliferation below the vestibular hair cells with disruption of the supporting cells. Electron microscopy further demonstrated inclusion bodies and cellular proliferation disturbing the normal neuroepithelial structure of the vestibular end-organs. Lastly, immunofluorescence (neurofilament 200 and synaptophysin) staining suggests that this cellular proliferation corresponds to afferent and efferent neuronal overgrowth. These data suggest that prosaposin plays a role not only in the maintenance of normal hearing but also an important role in the neuronal maturation processes of the vestibular sensory epithelium and the maintenance of normal vestibular system function. PMID:22326583

  14. Preservation of tap vestibular evoked myogenic potentials despite resection of the inferior vestibular nerve.

    PubMed

    Brantberg, Krister; Mathiesen, Tiit

    2004-01-01

    Sound and skull-tap induced vestibular evoked myogenic potentials (VEMP) were studied in a 43-year-old man following inferior vestibular neurectomy. Surgery was performed because of a small acoustic neuroma. Postoperative caloric testing suggested sparing of superior vestibular nerve function on the operated side. In response to sound stimulation there were no VEMP on the operated side, irrespective of whether sounds were presented by air- or bone-conduction. This suggests sound-induced VEMP to be critically dependent on inferior vestibular nerve function and this is in agreement with present knowledge. However, VEMP were obtained in response to forehead skull taps, i.e. positive-negative VEMP not only on the healthy side but also on the operated side. This suggests remnant vestibular function on the operated side of importance for forehead skull tap VEMP, because with complete unilateral vestibular loss there are no (positive-negative) VEMP on the lesioned side. Thus, forehead skull-tap VEMP depend, at least partly, on the superior vestibular nerve function. PMID:15328448

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

    PubMed Central

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

    2012-01-01

    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

  16. Vestibular-evoked myogenic potentials in three patients with large vestibular aqueduct.

    PubMed

    Sheykholeslami, Kianoush; Schmerber, Sébastien; Habiby Kermany, Mohammad; Kaga, Kimitaka

    2004-04-01

    An enlarged vestibular aqueduct (LVA) is a common congenital inner ear anomaly responsible for some unusual vestibular and audiological symptoms. Most of the cases show bilateral early onset and progressive hearing loss in children. The gross appearance on CT scan of the inner ear is generally normal. However, precise measurements of the inner ear components reveal abnormal dimensions, which may account for the accompanying auditory and vestibular dysfunction. Despite extensive studies on hearing and the vestibular apparatus, saccular function is not studied. To our knowledge this is the first report of saccular malfunction in three patients with LVA by means of vestibular evoked myogenic potentials. Conventional audiograms revealed bilateral severe sensorineural hearing loss in two patients and mixed type hearing loss in one patient. Two of the patients complained about vertigo and dizziness but vestibular assessments of the patients showed normal results. The diagnosis had been made by high-resolution CT scans and MR images of the skull that showed LVA in the absence of other anomalies. The VEMP threshold measured from the ear with LVA in two patients with unilateral enlargement of the vestibular aqueduct was 75-80 dB nHL whereas the threshold from normal ears was 95 dB nHL. The third patient with mixed type hearing loss and bilateral LVA had VEMP responses despite a big air-bone gap in the low frequency range. The VEMP in this patient was greater in amplitude and lower in threshold in the operated ear (the patient had a tympanoplasty which did not improve her hearing). These findings and results of other patients with Tullio phenomenon and superior semicircular canal dehiscence, who also showed lower VEMP threshold, confirmed the theory of a 'third window' that allows volume and pressure displacements, and thus larger deflection of the vestibular sensors, which would cause the vestibular organ to be more responsive to sound and pressure changes. PMID:15051138

  17. Mode of termination of primary vestibular fibres in the lateral vestibular nucleus an experimental electron microscopical study in the cat

    Microsoft Academic Search

    E. Mugnaini; F. Walberg; A. Brodal

    1967-01-01

    Following transection of the vestibular nerve in cats, the electron microscopical changes occurring in the lateral vestibular nucleus were studied after survival periods of 2–11 days. Material for study was taken from the rostroventral part of the nucleus of Deiters since this is known to receive the primary vestibular fibres.

  18. Vestibular schwannoma (acoustic neuroma) mimicking temporomandibular disorders: a case report.

    PubMed

    Bisi, Maurício A; Selaimen, Caio M P; Chaves, Karen D; Bisi, Melissa C; Grossi, Márcio L

    2006-12-01

    Approximately 6 to 16% of patients with trigeminal neuralgia symptoms present intracranial tumors, the most common being the vestibular schwannoma (acoustic neuroma). Some symptoms reported by patients include hearing loss, tinnitus, headaches, vertigo and trigeminal disturbances. An increased muscle response in the surrounding head and neck musculature may also be observed, which mimics signs and symptoms of temporomandibular disorders. In these cases, magnetic resonance imaging (MRI) has proved to be a useful tool in tumor diagnosis. The differential diagnosis between myofascial and neuralgic pain is important, as both may present similar characteristics, while being of different origin, and demanding special treatment approaches. The purpose of this paper is to demonstrate the relationship among trigeminal neuralgia symptoms, intracranial tumors and temporomandibular dysfunction by presenting a clinical case. PMID:19089251

  19. VESTIBULAR SCHWANNOMA (ACOUSTIC NEUROMA) MIMICKING TEMPOROMANDIBULAR DISORDERS: A CASE REPORT

    PubMed Central

    Bisi, Maurício A.; Selaimen, Caio M. P.; Chaves, Karen D.; Bisi, Melissa C.; Grossi, Márcio L.

    2006-01-01

    Approximately 6 to 16% of patients with trigeminal neuralgia symptoms present intracranial tumors, the most common being the vestibular schwannoma (acoustic neuroma). Some symptoms reported by patients include hearing loss, tinnitus, headaches, vertigo and trigeminal disturbances. An increased muscle response in the surrounding head and neck musculature may also be observed, which mimics signs and symptoms of temporomandibular disorders. In these cases, magnetic resonance imaging (MRI) has proved to be a useful tool in tumor diagnosis. The differential diagnosis between myofascial and neuralgic pain is important, as both may present similar characteristics, while being of different origin, and demanding special treatment approaches. The purpose of this paper is to demonstrate the relationship among trigeminal neuralgia symptoms, intracranial tumors and temporomandibular dysfunction by presenting a clinical case. PMID:19089251

  20. A systems concept of the vestibular organs

    NASA Technical Reports Server (NTRS)

    Mayne, R.

    1974-01-01

    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.

  1. Current Treatment of Vestibular, Ocular Motor Disorders and Nystagmus

    PubMed Central

    Brandt, Thomas

    2009-01-01

    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 Menière'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 Menière's disease, bilateral vestibular failure, vestibular paroxysmia, vestibular migraine, and many forms of central eye movement disorders. PMID:21179531

  2. Effects of EAS cochlear implantation surgery on vestibular function

    PubMed Central

    Tsukada, Keita; Moteki, Hideaki; Fukuoka, Hisakuni; Iwasaki, Satoshi

    2013-01-01

    Conclusions The patients who received electric acoustic stimulation (EAS) cochlear implantation had relatively good vestibular function compared with the patients who did not have residual hearing. The vestibular function was well preserved after atraumatic EAS surgery. The round window approach and soft electrode are preferred to decrease the risk of impairing vestibular function. Objectives The aim of this study was to examine the characteristic features of vestibular functions before and after implantations in patients undergoing EAS. Methods Vestibular functions in patients who underwent EAS implantation were examined by caloric testing and vestibular evoked myogenic potential (VEMP) in 11 patients before and in 13 patients after implantation. Results Preoperative evaluation showed that of the 11 patients, most (73%) had good vestibular function. One of 11 patients (9%) had decreased response in postoperative VEMP but all of the patients had unchanged results in postoperative caloric testing. PMID:24007563

  3. From ear to uncertainty: vestibular contributions to cognitive function

    PubMed Central

    Smith, Paul F.; Zheng, Yiwen

    2013-01-01

    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

  4. Inferior vestibular neuritis: 3 cases with clinical features of acute vestibular neuritis, normal calorics but indications of saccular failure

    PubMed Central

    Monstad, Per; Økstad, Siri; Mygland, Åse

    2006-01-01

    Background Vestibular neuritis (VN) is commonly diagnosed by demonstration of unilateral vestibular failure, as unilateral loss of caloric response. As this test reflects the function of the superior part of the vestibular nerve only, cases of pure inferior nerve neuritis will be lost. Case presentations We describe three patients with symptoms suggestive of VN, but normal calorics. All 3 had unilateral loss of vestibular evoked myogenic potential. A slight, asymptomatic position dependent nystagmus, with the pathological ear down, was observed. Conclusion We believe that these patients suffer from pure inferior nerve vestibular neuritis. PMID:17169144

  5. Towards a concept of disorders of “higher vestibular function”

    PubMed Central

    Brandt, Thomas; Strupp, Michael; Dieterich, Marianne

    2014-01-01

    Background: Vestibular disorders are commonly characterized by a combination of perceptual, ocular motor, postural, and vegetative manifestations, which cause the symptoms of vertigo, nystagmus, ataxia, and nausea. Multisensory convergence and numerous polysynaptic pathways link the bilaterally organized central vestibular network with limbic, hippocampal, cerebellar, and non-vestibular cortex structures to mediate “higher” cognitive functions. Anatomical classification of vestibular disorders: The traditional classification of vestibular disorders is based on the anatomical site of the lesion. While it distinguishes between the peripheral and the central vestibular systems, certain weaknesses become apparent when applied clinically. There are two reasons for this: first, peripheral and central vestibular disorders cannot always be separated by the clinical syndrome; second, a third category, namely disorders of “higher vestibular function”, is missing. These disorders may be caused by peripheral as well as central vestibular lesions. Functional classification: Here we discuss a new concept of disorders of higher vestibular function which involve cognition and more than one sensory modality. Three conditions are described that exemplify such higher disorders: room tilt illusion, spatial hemineglect, and bilateral vestibulopathy all of which present with deficits of orientation and spatial memory. Conclusions: Further elaboration of such disorders of higher multisensory functions with respect to lesion site and symptomatology is desirable. The room tilt illusion and spatial hemineglect involve vestibular and visual function to the extent that both conditions can be classified as either disorders of higher vestibular or of higher visual functions. A possible way of separating these disorders in a first step is to determine whether the causative lesion site affects the vestibular or the visual system. For the vestibular system this lesion site may be peripheral or central. The criterion of “higher function” is fulfilled if cognition or senses other than the primarily affected one come into play. PMID:24917796

  6. Vestibular convergence patterns in vestibular nuclei neurons of alert primates.

    PubMed

    Dickman, J David; Angelaki, Dora E

    2002-12-01

    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. PMID:12466465

  7. Vestibular convergence patterns in vestibular nuclei neurons of alert primates

    NASA Technical Reports Server (NTRS)

    Dickman, J. David; Angelaki, Dora E.

    2002-01-01

    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.

  8. Interaural difference values of vestibular evoked myogenic.

    PubMed

    Moallemi, Marziyeh; Hajiabolhassan, Fahimeh; Fatahi, Jamileh; Abolfazli, Roya; Jalaei, Shohre; Khamseh, Fatemeh

    2015-01-01

    Migraine is a neurologic disease, which often is associated with a unilateral headache. Vestibular abnormalities are common in migraine. Vestibular evoked myogenic potentials (VEMPs) assess otolith function in particular functional integrity of the saccule and the inferior vestibular nerve. We used VEMP to evaluate if the migraine headache can affect VEMP asymmetry parameters. A total of 25 patients with migraine (22 females and 3 males) who were diagnosed according to the criteria of IHS-1988 were enrolled in this cross-sectional study. Control group consisted of 26 healthy participants (18 female and 8 male), without neurotological symptoms and history of migraine. The short tone burst (95 dB nHL, 500 Hz) was presented to ears. VEMP was recorded with surface electromyography over the contracted ipsilateral sternocleidomastoid (SCM) muscle. Although current results showed that the amplitude ratio is greater in migraine patients than normal group, there was no statistical difference between two groups in mean asymmetry parameters of VEMP. Asymmetry measurements in vestibular evoked myogenic potentials probably are not indicators of unilateral deficient in saccular pathways of migraine patients. PMID:25597603

  9. Vestibular evoked myogenic potentials in Bell's palsy.

    PubMed

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

    2014-10-01

    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

  10. Vestibular Evoked Myogenic Potentials in Preterm Infants

    Microsoft Academic Search

    Seyra Erbek; Zeynel Gokmen; Servet Ozkiraz; Selim S. Erbek; Aylin Tarcan; Levent N. Ozluoglu

    2009-01-01

    The goal of this study was to determine whether there was an association between perinatal risk factors of prematurity and vestibular evoked myogenic potentials (VEMPs). A prospective case-control trial was designed. Fifty preterm newborns (100 ears) with a gestational age <37 weeks were included. The control group consisted of 20 healthy term infants (40 ears). VEMP recordings were performed, and

  11. Widespread Vestibular Activation of the Rodent Cortex

    PubMed Central

    Moya, Javier; Drawitsch, Florian; Brichta, Alan M.

    2015-01-01

    Much of our understanding of the neuronal mechanisms of spatial navigation is derived from chronic recordings in rodents in which head-direction, place, and grid cells have all been described. However, despite the proposed importance of self-reference information to these internal representations of space, their congruence with vestibular signaling remains unclear. Here we have undertaken brain-wide functional mapping using both fMRI and electrophysiological methods to directly determine the spatial extent, strength, and time course of vestibular signaling across the rat forebrain. We find distributed activity throughout thalamic, limbic, and particularly primary sensory cortical areas in addition to known head-direction pathways. We also observe activation of frontal regions, including infralimbic and cingulate cortices, indicating integration of vestibular information throughout functionally diverse cortical regions. These whole-brain activity maps therefore suggest a widespread contribution of vestibular signaling to a self-centered framework for multimodal sensorimotor integration in support of movement planning, execution, spatial navigation, and autonomic responses to gravito-inertial changes. PMID:25878265

  12. Widespread vestibular activation of the rodent cortex.

    PubMed

    Rancz, Ede A; Moya, Javier; Drawitsch, Florian; Brichta, Alan M; Canals, Santiago; Margrie, Troy W

    2015-04-15

    Much of our understanding of the neuronal mechanisms of spatial navigation is derived from chronic recordings in rodents in which head-direction, place, and grid cells have all been described. However, despite the proposed importance of self-reference information to these internal representations of space, their congruence with vestibular signaling remains unclear. Here we have undertaken brain-wide functional mapping using both fMRI and electrophysiological methods to directly determine the spatial extent, strength, and time course of vestibular signaling across the rat forebrain. We find distributed activity throughout thalamic, limbic, and particularly primary sensory cortical areas in addition to known head-direction pathways. We also observe activation of frontal regions, including infralimbic and cingulate cortices, indicating integration of vestibular information throughout functionally diverse cortical regions. These whole-brain activity maps therefore suggest a widespread contribution of vestibular signaling to a self-centered framework for multimodal sensorimotor integration in support of movement planning, execution, spatial navigation, and autonomic responses to gravito-inertial changes. PMID:25878265

  13. Large Vestibular Aqueduct Syndrome: A Genetic Disease?

    Microsoft Academic Search

    H. Ric Harnsberger; Richard T. Dahlen; John C. Carey; Kenneth Ward

    OBJECTIVE. Our objective was to determine the familial incidence of large vestibular aqueduct syndrome (LVAS) detected by CT and MR imaging and to propose the genetic inheritance of LVAS. MATERIALS AND METHODS. We retrospectively reviewed cases of LVAS revealed by temporal-bone CT and MR imaging at the University of Utah Health Sciences Center. We interviewed 25 patients with LVAS regarding

  14. WHY ARE CETACEANS' VESTIBULAR SYSTEMS SO

    E-print Network

    Wilson, David R.

    Inside JEB i WHY ARE CETACEANS' VESTIBULAR SYSTEMS SO SMALL? Of all of our six senses, balance is possibly the most underestimated. Lose it and you're in a bad way. Every terrestrial animal depends of his patients, the rancher offered to put Hullar in touch with a neighbour who breeds the animals

  15. Temporal Adaptation to delayed vestibular feedback

    E-print Network

    Temporal Adaptation to delayed vestibular feedback Douglas W. Cunningham, Björn Kreher, Markus von well demonstrated that delaying visual feedback impairs performance on a range of tasks. We have recently shown that a few minutes of exposure to delayed feedback induces sensorimotor temporal adaptation

  16. Vestibular effects on cerebral blood flow

    PubMed Central

    Serrador, Jorge M; Schlegel, Todd T; Black, F Owen; Wood, Scott J

    2009-01-01

    Background Humans demonstrate a number of unique adaptations that allow for the maintenance of blood pressure and brain blood flow when upright. While several physiological systems, including cerebral autoregulation, are involved in this adaptation the unique role the vestibular system plays in helping to maintain brain blood flow is just beginning to be elucidated. In this study, we tested the hypothesis that stimulation of the vestibular system, specifically the otoliths organs, would result in changes in cerebral blood flow. Results To test our hypothesis, we stimulated the vestibular organs of 25 healthy subjects by pitch tilt (stimulates both canals and otoliths) and by translation on a centrifuge (stimulates otoliths and not the canals) at five frequencies: 0.5, 0.25, 0.125 and 0.0625 Hz for 80 sec and 0.03125 Hz for 160 sec. Changes in cerebral flow velocity (by transcranial Doppler) and blood pressure (by Finapres) were similar during both stimuli and dependent on frequency of stimulation (P < 0.01). However, changes in cerebral blood flow were in opposition to changes in blood pressure and not fully dependent on changes in end tidal CO2. Conclusion The experimental results support our hypothesis and provide evidence that activation of the vestibular apparatus, specifically the otolith organs, directly affects cerebral blood flow regulation, independent of blood pressure and end tidal CO2 changes. PMID:19775430

  17. Genetics of recurrent vertigo and vestibular disorders.

    PubMed

    Gazquez, Irene; Lopez-Escamez, Jose A

    2011-09-01

    We present recent advances in the genetics of recurrent vertigo, including familial episodic ataxias, migraneous vertigo, bilateral vestibular hypofunction and Meniere's disease.Although several vestibular disorders are more common within families, the genetics of vestibulopathies is largely not known. Genetic loci and clinical features of familial episodic ataxias have been defined in linkage disequilibrium studies with mutations in neuronal genes KCNA1 and CACNA1A. Migrainous vertigo is a clinical disorder with a high comorbidity within families much more common in females with overlapping features with episodic ataxia and migraine. Bilateral vestibular hypofunction is a heterogeneous clinical group defined by episodes of vertigo leading to progressive loss of vestibular function which also can include migraine. Meniere's disease is a clinical syndrome characterized by spontaneous episodes of recurrent vertigo, sensorineural hearing loss, tinnitus and aural fullness and familial Meniere's disease in around 10-20% of cases. An international collaborative effort to define the clinical phenotype and recruiting patients with migrainous vertigo and Meniere's disease is ongoing for genome-wide association studies. PMID:22379397

  18. Genetics of Recurrent Vertigo and Vestibular Disorders

    PubMed Central

    Gazquez, Irene; Lopez-Escamez, Jose A

    2011-01-01

    We present recent advances in the genetics of recurrent vertigo, including familial episodic ataxias, migraneous vertigo, bilateral vestibular hypofunction and Meniere’s disease. Although several vestibular disorders are more common within families, the genetics of vestibulopathies is largely not known. Genetic loci and clinical features of familial episodic ataxias have been defined in linkage disequilibrium studies with mutations in neuronal genes KCNA1 and CACNA1A. Migrainous vertigo is a clinical disorder with a high comorbidity within families much more common in females with overlapping features with episodic ataxia and migraine. Bilateral vestibular hypofunction is a heterogeneous clinical group defined by episodes of vertigo leading to progressive loss of vestibular function which also can include migraine. Meniere’s disease is a clinical syndrome characterized by spontaneous episodes of recurrent vertigo, sensorineural hearing loss, tinnitus and aural fullness and familial Meniere’s disease in around 10-20% of cases. An international collaborative effort to define the clinical phenotype and recruiting patients with migrainous vertigo and Meniere’s disease is ongoing for genome-wide association studies. PMID:22379397

  19. Vestibular dysfunction in Gulf War syndrome

    Microsoft Academic Search

    PETER S. ROLAND; ROBERT W. HALEY; WENDY YELLIN; KRIS OWENS; ANGELA G. SHOUP

    2000-01-01

    Methods : Vestibular complaints of Gulf War veterans were characterized by a nested case-control study of 23 veterans with 3 different Gulf War syndromes and 20 matched control subjects. All subjects completed a standardized symptom questionnaire and underwent standard audiovestibular tests administered by audiologists blinded to group identities. Results : The prevalence of reported dizzy spells was higher in veterans

  20. Quantum stochastic approach for molecule\\/surface scattering. II. Adsorption resonances of He atoms on Xe overlayers

    Microsoft Academic Search

    Eric R. Bittner; John C. Light

    1994-01-01

    He scattering from Xe monolayers adsorbed onto Ag substrates is studied using a quantum stochastic method. Both the He atom and the surface and bulk modes are treated quantum mechanically using a mean-field partitioning of the quantum Liouville equation. The resulting equations of motion permit the evaluation of the reduced density matrix of the He atom subsystem by averaging over

  1. Whispering gallery modes in a microfiber coil with an n-fold helical symmetry:classical dynamics, stochasticity, long period gratings, and wave parametric resonance.

    PubMed

    Sumetsky, M

    2010-02-01

    Propagation of whispering gallery modes in a microfiber coil having an n-fold helical symmetry is considered. The n-fold helically symmetric deformations of a coiled microfiber is similar to a long period grating introduced by periodic microfiber bending with the azimuthal angle period 2pi/n. The considered modes are localized near a geodesic situated at the peripheral part of the microfiber surface. Using the perturbation theory, a simple condition for the stability of this geodesic is found. Violation of this condition happens in a small region localized near a point determined by the phase matching condition for the introduced long period grating. In the classical limit, the unstable region corresponds to the parametric resonance and stochastization of whispering gallery rays. Generally, this region corresponds to resonance intermode coupling, which may result either in the periodic transmission of radiation power between two modes or in the aperiodic wave parametric resonance, which causes simultaneous coupling and power transfer between numerous whispering gallery modes. The obtained results are important for engineering of miniature optical fiber coils and analysis of their propagation loss. PMID:20174071

  2. Electrical Vestibular Stimuli to Enhance Vestibulo-Motor Output and Improve Subject Comfort

    PubMed Central

    Forbes, Patrick A.; Dakin, Christopher J.; Geers, Anoek M.; Vlaar, Martijn P.; Happee, Riender; Siegmund, Gunter P.; Schouten, Alfred C.; Blouin, Jean-Sébastien

    2014-01-01

    Electrical vestibular stimulation is often used to assess vestibulo-motor and postural responses in both clinical and research settings. Stochastic vestibular stimulation (SVS) is a recently established technique with many advantages over its square-wave counterpart; however, the evoked muscle responses remain relatively small. Although the vestibular-evoked responses can be enhanced by increasing the stimulus amplitude, subjects often perceive these higher intensity electrical stimuli as noxious or painful. Here, we developed multisine vestibular stimulation (MVS) signals that include precise frequency contributions to increase signal-to-noise ratios (SNR) of stimulus-evoked muscle and motor responses. Subjects were exposed to three different MVS stimuli to establish that: 1) MVS signals evoke equivalent vestibulo-motor responses compared to SVS while improving subject comfort and reducing experimentation time, 2) stimulus-evoked vestibulo-motor responses are reliably estimated as a linear system and 3) specific components of the cumulant density time domain vestibulo-motor responses can be targeted by controlling the frequency content of the input stimulus. Our results revealed that in comparison to SVS, MVS signals increased the SNR 3–6 times, reduced the minimum experimentation time by 85% and improved subjective measures of comfort by 20–80%. Vestibulo-motor responses measured using both EMG and force were not substantially affected by nonlinear distortions. In addition, by limiting the contribution of high frequencies within the MVS input stimulus, the magnitude of the medium latency time domain motor output response was increased by 58%. These results demonstrate that MVS stimuli can be designed to target and enhance vestibulo-motor output responses while simultaneously improving subject comfort, which should prove beneficial for both research and clinical applications. PMID:24392130

  3. New insights into pathophysiology of vestibular migraine.

    PubMed

    Espinosa-Sanchez, Juan M; Lopez-Escamez, Jose A

    2015-01-01

    Vestibular migraine (VM) is a common disorder in which genetic, epigenetic, and environmental factors probably contribute to its development. The pathophysiology of VM is unknown; nevertheless in the last few years, several studies are contributing to understand the neurophysiological pathways involved in VM. The current hypotheses are mostly based on the knowledge of migraine itself. The evidence of trigeminal innervation of the labyrinth vessels and the localization of vasoactive neuropeptides in the perivascular afferent terminals of these trigeminal fibers support the involvement of the trigemino-vascular system. The neurogenic inflammation triggered by activation of the trigeminal-vestibulocochlear reflex, with the subsequent inner ear plasma protein extravasation and the release of inflammatory mediators, can contribute to a sustained activation and sensitization of the trigeminal primary afferent neurons explaining VM symptoms. The reciprocal connections between brainstem vestibular nuclei and the structures that modulate trigeminal nociceptive inputs (rostral ventromedial medulla, ventrolateral periaqueductal gray, locus coeruleus, and nucleus raphe magnus) are critical to understand the pathophysiology of VM. Although cortical spreading depression can affect cortical areas involved in processing vestibular information, functional neuroimaging techniques suggest a dysmodulation in the multimodal sensory integration and processing of vestibular and nociceptive information, resulting from a vestibulo-thalamo-cortical dysfunction, as the pathogenic mechanism underlying VM. The elevated prevalence of VM suggests that multiple functional variants may confer a genetic susceptibility leading to a dysregulation of excitatory-inhibitory balance in brain structures involved in the processing of sensory information, vestibular inputs, and pain. The interactions among several functional and structural neural networks could explain the pathogenic mechanisms of VM. PMID:25705201

  4. Neuronal loss in human medial vestibular nucleus.

    PubMed

    Alvarez, J C; Díaz, C; Suárez, C; Fernández, J A; González del Rey, C; Navarro, A; Tolivia, J

    1998-08-01

    The data concerning the effects of age on the brainstem are inconsistent, and few works are devoted to the human vestibular nuclear complex. The medial vestibular nucleus (MVN) is the largest nucleus of the vestibular nuclear complex, and it seems to be related mainly to vestibular compensation and vestibulo-ocular reflexes. Eight human brainstems have been used in this work. The specimens were embedded in paraffin, sectioned, and stained by the formaldehyde-thionin technique. Neuron profiles were drawn with a camera lucida at x330. Abercrombie's method was used to estimate the total number of neurons. We used the test of Kolmogorov-Smirnov with the correction of Lilliefors to evaluate the fit of our data to a normal distribution, and a regression analysis was performed to determine if the variation of our data with age was statistically significant. The present study clearly shows that neuronal loss occurs with aging. The total number of neurons decreases with age, from 122,241 +/- 651 cells in a 35-year-old individual to 75,915 +/- 453 cells in an 89-year-old individual. Neuron loss was significant in the caudal and intermediate thirds of the nucleus, whereas the changes in the rostral third were not significant. The nuclear diameter of surviving neurons decreased significantly with age. There is a neuron loss in the MVN that seems to be age-related. It could help explain why elderly people find it hard to compensate for unilateral vestibular deficits. The preservation of neurons in the rostral third could be related to the fact that this area primarily innervates the oculolmotor nuclei; these latter neurons do not decrease in number in other species studied. PMID:9713981

  5. Resonance

    NSDL National Science Digital Library

    Kuphaldt, Tony R.

    All About Circuits is a website that â??provides a series of online textbooks covering electricity and electronics.â? 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).

  6. Effects of whole-body vibration with stochastic resonance on balance in persons with balance disability and falls history - a systematic review.

    PubMed

    Rogan, Slavko; Hilfiker, Roger; Schenk, Adrian; Vogler, Aldo; Taeymans, Jan

    2014-01-01

    The aim of this systematic review was to identify and evaluate the evidence of the efficacy of stochastic resonance whole-body vibration (SR-WBV) on static, dynamic and functional balance in the elderly and in patients with neurodegenerative diseases. English and German studies were consulted in the CINAHL, Cochrane Central Register of Controlled Trials, ISI Web of Knowledge, PEDro and PubMed databases. Eight of 138 eligible studies were included, involving 381 participants. The included studies showed a low to high risk of bias. Three studies focused on long-term effects after SR-WBV. One study evaluated SR-WBV impact over three days while four studies examined its immediate effects. There is only limited evidence that SR-WBV may be effective in improving static, dynamic and functional balance among elderly individuals and patients with neurodegenerative diseases. In the future, more studies of high methodological quality are needed to improve the level of evidence. PMID:24950116

  7. Presynaptic GABAB Receptors Decrease Neurotransmitter Release in Vestibular Nuclei Neurons During Vestibular Compensation

    PubMed Central

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

    2013-01-01

    Unilateral damage to the peripheral vestibular receptors precipitates a debilitating syndrome of oculomotor and balance deficits at rest, which extensively normalize during the first week after the lesion due to vestibular compensation. In vivo studies suggest that GABAB receptor activation facilitates recovery. However, the presynaptic or postsynaptic sites of action of GABAB receptors in vestibular nuclei neurons after lesions have not been determined. Accordingly, here presynaptic and postsynaptic GABAB receptor activity in principal cells of the tangential nucleus, a major avian vestibular nucleus, was investigated using patch-clamp recordings correlated with immunolabeling and confocal imaging of the GABAB receptor subunit-2 (GABABR2) in controls and operated chickens shortly after unilateral vestibular ganglionectomy (UVG). Baclofen, a GABAB agonist, generated no postsynaptic currents in principal cells in controls, which correlated with weak GABABR2 immunolabeling on principal cell surfaces. However, baclofen decreased miniature excitatory (mEPSC) and GABAergic inhibitory (mIPSC) events in principal cells in controls, compensating and uncompensated chickens three days after UVG, indicating the presence of functional GABAB receptors on presynaptic terminals. Baclofen decreased GABAergic mIPSC frequency to the greatest extent in principal cells on the intact side of compensating chickens, with concurrent increases in GABABR2 pixel brightness and percentage overlap in synaptotagmin2 (Syt2)-labeled terminals. In uncompensated chickens, baclofen decreased mEPSC frequency to the greatest extent in principal cells on the intact side, with concurrent increases in GABABR2 pixel brightness and percentage overlap in Syt1-labeled terminals. Altogether, these results revealed changes in presynaptic GABAB receptor function and expression which differed in compensating and uncompensated chickens shortly after UVG. This work supports an important role for GABAB autoreceptor-mediated inhibition in vestibular nuclei neurons on the intact side during early stages of vestibular compensation, and a role for GABAB heteroreceptor-mediated inhibition of glutamatergic terminals on the intact side in the failure to recover function. PMID:22871524

  8. Vestibular testing by electrical stimulation in patients with unilateral vestibular deafferentation: galvanic evoked myogenic responses testing versus galvanic body sway testing

    Microsoft Academic Search

    Hiroko Monobe; Toshihisa Murofushi

    2004-01-01

    Objective: To investigate the agreement of a lesion site as indicated by two different vestibular tests with electrical stimulation, galvanic body sway testing (GBST) and galvanic evoked myogenic responses (galvanic vestibular evoked myogenic potential; galvanic VEMP) testing, in patients with unilateral vestibular deafferentation.Methods: Nineteen patients with unilateral vestibular deafferentation were studied, and the criteria for patient selection were as follows:

  9. Response of guinea pig vestibular nucleus neurons to clicks

    Microsoft Academic Search

    Toshihisa Murofushi; Ian S. Curthoys; Darrin P. Gilchrist

    1996-01-01

    Responses of single neurons in the vestibular nuclei to clicks were studied by extracellular recording in anaesthetised guinea pigs. Eighty-four neurons in the ipsilateral vestibular nuclei were activated with an average latency of 1.75±0.30 ms, which is about 0.9 ms longer than the mean latency of activation of click-sensitive vestibular afferents to intense clicks. The threshold of clicks for evoking

  10. New methods for diagnosis and treatment of vestibular diseases

    PubMed Central

    Palla, Antonella

    2010-01-01

    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

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

    PubMed Central

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

    2013-01-01

    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

  12. Inferior vestibular neuritis in a fighter pilot: a case report.

    PubMed

    Xie, Su Jiang; Jia, Hong Bo; Xu, Po; Zheng, Ying Juan

    2013-06-01

    Spatial disorientation in airplane pilots is a leading factor in many fatal flying accidents. Spatial orientation is the product of integrative inputs from the proprioceptive, vestibular, and visual systems. One condition that can lead to sudden pilot incapacitation in flight is vestibular neuritis. Vestibular neuritis is commonly diagnosed by a finding of unilateral vestibular failure, such as a loss of caloric response. However, because caloric response testing reflects the function of only the superior part of the vestibular nerve, it cannot detect cases of neuritis in only the inferior part of the nerve. We describe the case of a Chinese naval command fighter pilot who exhibited symptoms suggestive of vestibular neuritis but whose caloric response test results were normal. Further testing showed a unilateral loss of vestibular evoked myogenic potentials (VEMPs). We believe that this pilot had pure inferior nerve vestibular neuritis. VEMP testing plays a major role in the diagnosis of inferior nerve vestibular neuritis in pilots. We also discuss this issue in terms of aeromedical concerns. PMID:23780600

  13. Task, muscle and frequency dependent vestibular control of posture

    PubMed Central

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

    2015-01-01

    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

  14. Implementation of a neuromorphic vestibular sensor with analog VLSI neurons

    E-print Network

    could be easily integrated in robotic applications based on low-power, highly parallel neuromorphic computational architectures. This work shows an implementation of a neuromorphic vestibular sensor using

  15. Direction Specific Biases in Human Visual and Vestibular Heading Perception

    PubMed Central

    Crane, Benjamin T.

    2012-01-01

    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

  16. What galvanic vestibular stimulation actually activates.

    PubMed

    Curthoys, Ian S; Macdougall, Hamish Gavin

    2012-01-01

    In a recent paper in Frontiers Cohen et al. (2012) asked "What does galvanic vestibular stimulation actually activate?" and concluded that galvanic vestibular stimulation (GVS) causes predominantly otolithic behavioral responses. In this Perspective paper we show that such a conclusion does not follow from the evidence. The evidence from neurophysiology is very clear: galvanic stimulation activates primary otolithic neurons as well as primary semicircular canal neurons (Kim and Curthoys, 2004). Irregular neurons are activated at lower currents. The answer to what behavior is activated depends on what is measured and how it is measured, including not just technical details, such as the frame rate of video, but the exact experimental context in which the measurement took place (visual fixation vs total darkness). Both canal and otolith dependent responses are activated by GVS. PMID:22833733

  17. Experiment M131. Human vestibular function

    NASA Technical Reports Server (NTRS)

    Graybiel, A.; Miller, E. F., II; Homick, J. L.

    1977-01-01

    The lower susceptibility to vestibular stimulation aloft, compared with that on ground under experimental conditions, is attributed to a precondition, namely, either there is no need to adapt, or, as exemplified by the Skylab 3 pilot, adaptation to weightlessness is achieved. Findings in some of the astronauts emphasize the distinction between two categories of vestibular side effects: immediate reflex phenomena (illusions, sensations of turning, etc.), and delayed epiphenomena that include the constellation of symptoms and syndromes comprising motion sickness. The drug combinations 1-scopolamine and d-amphetamine and promethazine hydrochloride and ephedrine sulfate are effective in prevention and treatment of motion sickness. It is concluded that prevention of motion sickness in any stressful motion environment involves selection, adaptation, and the use of drugs.

  18. Vestibular efferent neurons project to the flocculus

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  19. The vestibular system of the owl

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    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.

  20. Vestibular evoked myogenic potentials to sound and vibration: characteristics in vestibular migraine that enable separation from Menière’s disease

    Microsoft Academic Search

    Rachael L Taylor; Alessandro S Zagami; William PR Gibson; Deborah A Black; Michael G Halmagyi; Miriam S Welgampola

    2012-01-01

    Objectives: It can be difficult to distinguish vestibular migraine (VM) from Menière’s disease (MD) in its early stages. Using vestibular-evoked myogenic potentials (VEMPs), we sought to identify test parameters that would help discriminate between these two vestibular disorders.Methods: We first recorded ocular and cervical VEMPs (oVEMP\\/cVEMP) to air-conducted clicks and bone-conducted vibration in 30 control participants, 30 participants with clinically

  1. Galvanic vestibular stimulation: a novel modulatory countermeasure for vestibular-associated movement disorders.

    PubMed

    Rizzo-Sierra, Carlos V; Gonzalez-Castaño, Alexander; Leon-Sarmiento, Fidias E

    2014-01-01

    Motion sickness or kinetosis is the result of the abnormal neural output originated by visual, proprioceptive and vestibular mismatch, which reverses once the dysfunctional sensory information becomes coherent. The space adaptation syndrome or space sickness relates to motion sickness; it is considered to be due to yaw, pith, and roll coordinates mismatch. Several behavioural and pharmacological measures have been proposed to control these vestibular-associated movement disorders with no success. Galvanic vestibular stimulation has the potential of up-regulating disturbed sensory-motor mismatch originated by kinetosis and space sickness by modulating the GABA-related ion channels neural transmission in the inner ear. It improves the signal-to-noise ratio of the afferent proprioceptive volleys, which would ultimately modulate the motor output restoring the disordered gait, balance and human locomotion due to kinetosis, as well as the spatial disorientation generated by gravity transition. PMID:24637984

  2. Vestibular Evoked Myogenic Potentials in Newborns

    Microsoft Academic Search

    Chun-Nan Chen; Shou-Jen Wang; Chi-Te Wang; Wu-Shiun Hsieh; Yi-Ho Young

    2007-01-01

    This study presents a novel method for recording vestibular evoked myogenic potential (VEMP) in newborns, used to investigate the maturation of sacculocollic reflex at birth.Twenty full-term newborns aged 2–5 days old were enrolled in this study. During natural sleep, each newborn underwent distortion product otoacoustic emission test, and VEMP test using the head rotation method. For comparison, 20 healthy adults

  3. Vestibular Schwannoma, Tinnitus and Cellular Telephones

    Microsoft Academic Search

    Lennart Hardell; Kjell Hansson Mild; Monica Sandström; Michael Carlberg; Arne Hallquist; Anneli Påhlson

    2003-01-01

    Cases with tinnitus after using analogue cellular telephones are presented. An increased odds ratio of 3.45, 95% confidence interval (CI) 1.77–6.76, was found for vestibular schwannoma (VS) associated with the use of analogue cell phones. During the time period 1960–1998, the age-standardized incidence of VS in Sweden significantly increased yearly by +2.53% (CI 1.71–3.35). A significant increase in the incidence

  4. Spatial and temporal characteristics of vestibular convergence

    PubMed Central

    McArthur, Kimberly L.; Zakir, Mridha; Haque, Asim; Dickman, J. David

    2011-01-01

    In all species studied, afferents from semicircular canals and otolith organs converge on central neurons in the brainstem. However, the spatial and temporal relationships between converging inputs and how these contribute to vestibular behaviors is not well understood. In the current study, we used discrete rotational and translational motion stimuli to characterize canal- and otolith-driven response components of convergent non-eye movement (NEM) neurons in the vestibular nuclear complex of alert pigeons. When compared to afferent responses, convergent canal signals had similar gain and phase ranges but exhibited greater spatial variability in their axes of preferred rotation. Convergent otolith signals also had similar mean gain and phase values to the afferent population but were spatially well-matched with the corresponding canal signals, cell-by-cell. However, neither response component alone nor a simple linear combination of these components was sufficient to predict actual net responses during combined canal-otolith stimulation. We discuss these findings in the context of previous studies of pigeon vestibular behaviors, and we compare our findings to similar studies in other species. PMID:21756981

  5. Integration of vestibular and head movement signals in the vestibular nuclei during whole-body rotation

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    Single-unit recordings were obtained from 107 horizontal semicircular canal-related central vestibular neurons in three alert squirrel monkeys during passive sinusoidal whole-body rotation (WBR) while the head was free to move in the yaw plane (2.3 Hz, 20 degrees /s). Most of the units were identified as secondary vestibular neurons by electrical stimulation of the ipsilateral vestibular nerve (61/80 tested). Both non-eye-movement (n = 52) and eye-movement-related (n = 55) units were studied. Unit responses recorded when the head was free to move were compared with responses recorded when the head was restrained from moving. WBR in the absence of a visual target evoked a compensatory vestibulocollic reflex (VCR) that effectively reduced the head velocity in space by an average of 33 +/- 14%. In 73 units, the compensatory head movements were sufficiently large to permit the effect of the VCR on vestibular signal processing to be assessed quantitatively. The VCR affected the rotational responses of different vestibular neurons in different ways. Approximately one-half of the units (34/73, 47%) had responses that decreased as head velocity decreased. However, the responses of many other units (24/73) showed little change. These cells had signals that were better correlated with trunk velocity than with head velocity. The remaining units had responses that were significantly larger (15/73, 21%) when the VCR produced a decrease in head velocity. Eye-movement-related units tended to have rotational responses that were correlated with head velocity. On the other hand, non-eye-movement units tended to have rotational responses that were better correlated with trunk velocity. We conclude that sensory vestibular signals are transformed from head-in-space coordinates to trunk-in-space coordinates on many secondary vestibular neurons in the vestibular nuclei by the addition of inputs related to head rotation on the trunk. This coordinate transformation is presumably important for controlling postural reflexes and constructing a central percept of body orientation and movement in space.

  6. Resonant control of stochastic spatio-temporal dynamics in a tunnel diode by multiple time delayed feedback

    E-print Network

    Majer, Niels

    2008-01-01

    We study the control of noise-induced spatio-temporal current density patterns in a semiconductor nanostructure (double barrier resonant tunnelling diode) by multiple time-delayed feedback. We find much more pronounced resonant features of noise-induced oscillations compared to single time feedback, rendering the system more sensitive to variations in the delay time $\\tau$. The coherence of noise-induced oscillations measured by the correlation time exhibits sharp resonances as a function of $\\tau$, and can be strongly increased by optimal choices of $\\tau$. Similarly, the peaks in the power spectral density are sharpened. We provide analytical insight into the control mechanism by relating the correlation times and mean frequencies of noise-induced breathing oscillations to the stability properties of the deterministic stationary current density filaments under the influence of the control loop. Moreover, we demonstrate that the use of multiple time delays enlarges the regime in which the deterministic dynam...

  7. Differential central projections of vestibular afferents in pigeons

    NASA Technical Reports Server (NTRS)

    Dickman, J. D.; Fang, Q.

    1996-01-01

    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.

  8. 1526 IEEE TRANSACTIONS ON NEURAL NETWORKS, VOL. 15, NO. 6, NOVEMBER 2004 Adaptive Stochastic Resonance in Noisy Neurons

    E-print Network

    Kosko, Bart

    and engineers have largely tried to filter noise or cancel it or mask it out of existence. The Noise Pollution' meaning seasickness. Noise is among the most pervasive pollutants today. Noise from road traffic, jet Resonance in Noisy Neurons Based on Mutual Information Sanya Mitaim and Bart Kosko Abstract--Noise can

  9. Age-Related Changes in Vestibular Evoked Myogenic Potentials

    Microsoft Academic Search

    Krister Brantberg; Kerstin Granath; Nadine Schart

    2007-01-01

    Vestibular evoked myogenic potentials (VEMP) in response to sound stimulation (500 Hz tone burst, 129 dB SPL) were studied in 1000 consecutive patients. VEMP from the ear with the larger amplitude were evaluated based on the assumption that the majority of the tested patients probably had normal vestibular function in that ear. Patients with known bilateral conductive hearing loss, with

  10. Vestibular receptors contribute to cortical auditory evoked potentials?

    PubMed Central

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

    2014-01-01

    Acoustic sensitivity of the vestibular apparatus is well-established, but the contribution of vestibular receptors to the late auditory evoked potentials of cortical origin is unknown. Evoked potentials from 500 Hz tone pips were recorded using 70 channel EEG at several intensities below and above the vestibular acoustic threshold, as determined by vestibular evoked myogenic potentials (VEMPs). In healthy subjects both auditory mid- and long-latency auditory evoked potentials (AEPs), consisting of Na, Pa, N1 and P2 waves, were observed in the sub-threshold conditions. However, in passing through the vestibular threshold, systematic changes were observed in the morphology of the potentials and in the intensity dependence of their amplitude and latency. These changes were absent in a patient without functioning vestibular receptors. In particular, for the healthy subjects there was a fronto-central negativity, which appeared at about 42 ms, referred to as an N42, prior to the AEP N1. Source analysis of both the N42 and N1 indicated involvement of cingulate cortex, as well as bilateral superior temporal cortex. Our findings are best explained by vestibular receptors contributing to what were hitherto considered as purely auditory evoked potentials and in addition tentatively identify a new component that appears to be primarily of vestibular origin. PMID:24321822

  11. Vestibular Evoked Myogenic Potentials in Patients with Idiopathic Bilateral Vestibulopathy

    Microsoft Academic Search

    Masaki Matsuzaki; Toshihisa Murofushi

    2001-01-01

    Idiopathic bilateral vestibulopathy (IBV) is an acquired bilateral peripheral vestibular disorder of unknown cause. Three patients diagnosed as IBV by neuro-otological examination were reported. They underwent vestibular evoked myogenic potential (VEMP) testing which reflects the functionality of the sacculo-collic pathway. As a result, 2 of the 3 patients showed bilateral absence of VEMPs and one showed unilateral absence. The VEMPs

  12. Effect of meprobamate on the vestibulosensory and vestibular somatic reaction

    NASA Technical Reports Server (NTRS)

    Khinchikashvili, N. V.

    1980-01-01

    The influence of meprobamate on the vestibular illusion of counter-rotation, movement coordination and vertical writing was investigated by a double blind trial method and placebo. The results confirm the possibility of the meprobamate application for prophylaxis and correction of vestibular disturbances.

  13. Sensory processing in the vestibular nuclei during active head movements

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    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.

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

    PubMed

    Brantberg, Krister

    2009-11-01

    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 Ménière'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

  15. Vestibular Dreams: The Effect of Rocking on Dream Mentation

    Microsoft Academic Search

    Kenneth Leslie; Robert Ogilvie

    1996-01-01

    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.

  16. ORIGINAL ARTICLE An Observed Relationship Between Vestibular Function and

    E-print Network

    Boggess, May M.

    solvent.2 The damaging effect of noise on vestibular disturbance is well known. First described in 1890 in Aircraft-Maintenance Workers Maya Guest, BMedSci (Hon), May Boggess, PhD, Catherine D'Este, PhD, John Attia an association exists between vestibular function and hearing thresholds in a group of military aircraft

  17. Balancing the mind: vestibular induced facilitation of egocentric mental transformations.

    PubMed

    Falconer, Caroline J; Mast, Fred W

    2012-01-01

    The body schema is a key component in accomplishing egocentric mental transformations, which rely on bodily reference frames. These reference frames are based on a plurality of different cognitive and sensory cues among which the vestibular system plays a prominent role. We investigated whether a bottom-up influence of vestibular stimulation modulates the ability to perform egocentric mental transformations. Participants were significantly faster to make correct spatial judgments during vestibular stimulation as compared to sham stimulation. Interestingly, no such effects were found for mental transformation of hand stimuli or during mental transformations of letters, thus showing a selective influence of vestibular stimulation on the rotation of whole-body reference frames. Furthermore, we found an interaction with the angle of rotation and vestibular stimulation demonstrating an increase in facilitation during mental body rotations in a direction congruent with rightward vestibular afferents. We propose that facilitation reflects a convergence in shared brain areas that process bottom-up vestibular signals and top-down imagined whole-body rotations, including the precuneus and tempero-parietal junction. Ultimately, our results show that vestibular information can influence higher-order cognitive processes, such as the body schema and mental imagery. PMID:22750744

  18. A vestibular sensation: probabilistic approaches to spatial perception.

    PubMed

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

    2009-11-25

    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

  19. Assessment of auditory and vestibular functions after vestibular neurectomy for Menière's disease.

    PubMed

    Kubo, T; Doi, K; Koizuka, I; Takeda, N; Sugiyama, N; Yamada, K; Kohmura, E; Hayakawa, T

    1995-03-01

    Fourteen patients (12 Meniere's disease, one delayed endolymphatic hydrops and one labyrinthitis) suffering from intractable vertigo were treated with retrosigmoid vestibular neurectomy (RSVN) in our institute. Dizziness was controlled completely in all patients. Hearing was preserved in 91.7% of the cases with pure tone threshold deteriorating by more than 10 dB in one case, remained unchanged in 10 cases and improved in one case during long term observation. Substantial decrease of tinnitus was observed in 78.6%. Vestibular compensation was chronologically analyzed with a stabilometer, ENG and vestibular rotation test (0.01-0.64 Hz). Vestibular compensation under static conditions was accomplished within 2 weeks, except for spontaneous nystagmus measured in the dark. Asymmetry of vestibulo-ocular reflex was noted 2 weeks after the operation but had disappeared after 4 weeks. However, for over 2 years the VOR time constant remained lower (4.3-5.2 s) than the pre-operative value (8.2 s). Electro-cochleogram (ECoG) was recorded before and after RSVN. The -SP/AP ratio tended to increase after RSVN in the operated ear, though there was no change in the contralateral ear. The efferent olivo-cochlear bundle was thought to play a potential role in this increase of the -SP/AP ratio. PMID:7610792

  20. Presynaptic GABA(B) receptors decrease neurotransmitter release in vestibular nuclei neurons during vestibular compensation.

    PubMed

    Shao, M; Reddaway, R; Hirsch, J C; Peusner, K D

    2012-10-25

    Unilateral damage to the peripheral vestibular receptors precipitates a debilitating syndrome of oculomotor and balance deficits at rest, which extensively normalize during the first week after the lesion due to vestibular compensation. In vivo studies suggest that GABA(B) receptor activation facilitates recovery. However, the presynaptic or postsynaptic sites of action of GABA(B) receptors in vestibular nuclei neurons after lesions have not been determined. Accordingly, here presynaptic and postsynaptic GABA(B) receptor activity in principal cells of the tangential nucleus, a major avian vestibular nucleus, was investigated using patch-clamp recordings correlated with immunolabeling and confocal imaging of the GABA(B) receptor subunit-2 (GABA(B)R2) in controls and operated chickens shortly after unilateral vestibular ganglionectomy (UVG). Baclofen, a GABA(B) agonist, generated no postsynaptic currents in principal cells in controls, which correlated with weak GABA(B)R2 immunolabeling on principal cell surfaces. However, baclofen decreased miniature excitatory postsynaptic current (mEPSC) and GABAergic miniature inhibitory postsynaptic current (mIPSC) events in principal cells in controls, compensating and uncompensated chickens three days after UVG, indicating the presence of functional GABA(B) receptors on presynaptic terminals. Baclofen decreased GABAergic mIPSC frequency to the greatest extent in principal cells on the intact side of compensating chickens, with concurrent increases in GABA(B)R2 pixel brightness and percentage overlap in synaptotagmin 2-labeled terminals. In uncompensated chickens, baclofen decreased mEPSC frequency to the greatest extent in principal cells on the intact side, with concurrent increases in GABA(B)R2 pixel brightness and percentage overlap in synaptotagmin 1-labeled terminals. Altogether, these results revealed changes in presynaptic GABA(B) receptor function and expression which differed in compensating and uncompensated chickens shortly after UVG. This work supports an important role for GABA(B) autoreceptor-mediated inhibition in vestibular nuclei neurons on the intact side during early stages of vestibular compensation, and a role for GABA(B) heteroreceptor-mediated inhibition of glutamatergic terminals on the intact side in the failure to recover function. PMID:22871524

  1. Vestibular nucleus projections to the parabrachial nucleus in rabbits: implications for vestibular influences on the autonomic nervous system

    Microsoft Academic Search

    Carey D. Balaban

    1996-01-01

    Acute vestibular dysfunction and motion sickness are characterized by autonomic effects such as pallor, nausea, and vomiting. Previous anatomic and physiologic studies suggest that one potential mediator of these effects may be light, direct vestibular nuclear projections to the nucleus tractus solitarius and the dorsal motor nucleus of the vagus nerve. This study presents evidence for relatively dense, direct projections

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

    Microsoft Academic Search

    Christian Beier; Heinz-Jürgen Steinhoff

    2006-01-01

    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

  3. The role of the vestibular system in manual target localization

    NASA Technical Reports Server (NTRS)

    Barry, Susan R.; Mueller, S. Alyssa

    1995-01-01

    Astronauts experience perceptual and sensory-motor disturbances during spaceflight and immediately after return to the 1-g environment of Earth. During spaceflight, sensory information from the eyes, limbs and vestibular organs is reinterpreted by the central nervous system so that astronauts can produce appropriate body movements in microgravity. Alterations in sensory-motor function may affect eye-head-hand coordination and, thus, the crewmember's ability to manually locate objects in extrapersonal space. Previous reports have demonstrated that crewmembers have difficulty in estimating joint and limb position and in pointing to memorized target positions on orbit and immediately postflight. One set of internal cues that may assist in the manual localization of objects is information from the vestibular system. This system contributes to our sense of the body's position in space by providing information on head position and movement and the orientation of the body with respect to gravity. Research on the vestibular system has concentrated on its role in oculo-motor control. Little is known about the role that vestibular information plays in manual motor control, such as reaching and pointing movements. Since central interpretation of vestibular information is altered in microgravity, it is important to determine its role in this process. This summer, we determined the importance of vestibular information in a subject's ability to point accurately toward a target in extrapersonal space. Subjects were passively rotated across the earth-vertical axis and then asked to point back to a previously-seen target. In the first paradigm, the subjects used both visual and vestibular cues for the pointing response, while, in the second paradigm, subjects used only vestibular information. Subjects were able to point with 85 percent accuracy to a target using vestibular information alone. We infer from this result that vestibular input plays a role in the spatial programming of manual responses.

  4. Anodal vestibular stimulation does not suppress vestibular reflexes in human subjects.

    PubMed

    Bacsi, Ann M; Colebatch, James G

    2003-06-01

    Anodal current applied to the vestibular apparatus has previously been found to inhibit discharge from irregular vestibular afferents in squirrel monkeys. We wished to investigate whether anodal currents applied over the mastoid processes of human subjects would significantly reduce ongoing vestibular activity and thereby the size of galvanic-evoked vestibulospinal reflexes, measured by soleus electromyogram. Nine subjects were tested, of whom six subjects (five females, one male) provided data for the final analysis. Tonic anodal current was applied over one mastoid at 0 (baseline), 2, 4, 6 and 8 mA. The cathode was placed at C7. Superimposed on each intensity of tonic current were separate, short anodal currents of 4 mA, duration 20 ms, presented as 128 stimuli to the same side, and used to test vestibular responsiveness. These trials were then repeated with the anode overlying the contralateral mastoid. Short latency (SL) and medium latency (ML) reflexes were measured from the right soleus muscle. All six subjects used in the final analysis had readily identifiable reflexes to all stimuli. One-way ANOVA revealed no significant difference in the magnitude of the SL ( P=0.99) or ML ( P=0.96) components of the vestibulospinal reflexes across the group. Despite surface anodal currents of up to 8 mA, there was no consistent effect on the size of galvanic-evoked vestibulospinal reflexes. As 8 mA is close to the maximum intensity tolerated by volunteer subjects, our results indicate that anodal current applied over the mastoids is unlikely to be a useful means of suppressing vestibular function in human subjects. PMID:12739094

  5. Human Vestibular Function - Skylab Experiment M131

    NASA Technical Reports Server (NTRS)

    1972-01-01

    This set of photographs details Skylab's Human Vestibular Function experiment (M131). This experiment was a set of medical studies designed to determine the effect of long-duration space missions on astronauts' coordination abilities. This experiment tested the astronauts susceptibility to motion sickness in the Skylab environment, acquired data fundamental to an understanding of the functions of human gravity reception under prolonged absence of gravity, and tested for changes in the sensitivity of the semicircular canals. Data from this experiment was collected before, during, and after flight. The Marshall Space Flight Center had program management responsibility for the development of Skylab hardware and experiments.

  6. Experiment M-131 - Human vestibular function.

    NASA Technical Reports Server (NTRS)

    Miller, E. F., II; Graybiel, A.

    1973-01-01

    The purpose of the M-131 experiment is to measure responses in astronauts throughout orbital flight that reflect vestibular function and compare them with measurements made before and after flight. Three subtasks require measurement of (1) susceptibility to motion sickness, (2) thresholds of response to stimulation of the semicircular canals, and (3) space perception, viz, visual and nonvisual localization, using external spacecraft and internal morphological frames of reference. Four astronauts will be available for all measurements in Skylab 2 and 3 and two additional astronauts for only the 'static' measurements during the flights.

  7. Vestibular function in the space environment

    NASA Technical Reports Server (NTRS)

    Von Baumgarten, R. J.; Harth, O.; Thuemler, R.; Baldrighi, G.; Shillinger, G. L., Jr.

    1975-01-01

    The present work presents new results about the interdependence of optical illusory sensations and eye movements in man. To establish to what degree certain illusions previously obtained during centrifugation and parabolic flight can be explained by eye movements and by neuronal integration in the brain, real eye movements were measured as they occurred in the dark without optical fixation, during rectilinear accelerations on the ground, and during weightlessness in parabolic flight. Results provide valuable insight into normal vestibular function as well as resolution of within-the-eye and behind-the-eye contributions to the above illusions.

  8. Symptomatic Recovery in Miller Fisher Syndrome Parallels Vestibular-Perceptual and not Vestibular-Ocular Reflex Function.

    PubMed

    Seemungal, Barry M; Masaoutis, Panos; Green, David A; Plant, Gordon T; Bronstein, Adolfo M

    2011-01-01

    Unpleasant visual symptoms including oscillopsia and dizziness may occur when there is unexpected motion of the visual world across the subject's retina ("retinal slip") as in an acute spontaneous nystagmus or on head movement with an acute ophthalmoplegia. In contrast, subjects with chronic ocular dysmotility, e.g., congenital nystagmus or chronic progressive external ophthalmoplegia, are typically symptom free. The adaptive processes that render chronic patients asymptomatic are obscure but may include a suppression of oscillopsia perception as well as an increased tolerance to perceived oscillopsia. Such chronic asymptomatic patients display an attenuation of vestibular-mediated angular velocity perception, implying a possible contributory role in the adaptive process. In order to assess causality between symptoms, signs (i.e., eye movements), and vestibular-perceptual function, we prospectively assessed symptom ratings and ocular-motor and perceptual vestibular function, in a patient with acute but transient ophthalmoplegia due to Miller Fisher Syndrome (as a model of visuo-vestibular adaptation). The data show that perceptual measures of vestibular function display a significant attenuation as compared to ocular-motor measures during the acute, symptomatic period. Perhaps significantly, both symptomatic recovery and normalization of vestibular-perceptual function were delayed and then occurred in a parallel fashion. This is the first report showing that symptomatic recovery of visuo-vestibular symptoms is better paralleled by vestibular-perceptual testing than vestibular-ocular reflex (VOR) measures. The findings may have implications for the understanding of patients with chronic vestibular symptoms where VOR testing is often unhelpful. PMID:21350734

  9. Altered vestibular function in fetal and newborn rats gestated in space

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    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.

  10. The vestibular-basal ganglia connection: balancing motor control.

    PubMed

    Stiles, Lucy; Smith, Paul F

    2015-02-01

    Connections between the vestibular system and the basal ganglia have been sporadically studied over the last century. Electrophysiological studies of field potentials in animals have shown that most areas of the striatum respond to electrical vestibular stimulation while human studies isolated responses to vestibular stimulation to the putamen of the striatum. Protein studies have shown inconsistent results regarding changes in receptor levels of a number of receptor types. Recent tracer studies identified a pathway between the vestibular nucleus and the striatum via the thalamus, completely bypassing the cortex. Vestibular sensory input is represented in the part of the striatum - the dorsolateral striatum - where fibres from the sensorimotor areas terminate. It is therefore possible that vestibular signals are used together with other sensorimotor inputs in the striatum for body and limb control. The combination of electrophysiological results, changes in protein levels and tracer studies have led to the idea that the dorsolateral striatum is likely to be the main input area for vestibular signals in the basal ganglia and these will have an influence on motor control. This may have clinical implications in the treatment of basal ganglia disorders and other movement disorders. PMID:25498858

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

    PubMed Central

    Song, Hyun Seok; Kim, Ji Soo

    2011-01-01

    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

  12. Assessment of Vestibular Rehabilitation Therapy Training and Practice Patterns.

    PubMed

    Bush, Matthew L; Dougherty, William

    2015-08-01

    Vestibular rehabilitation therapy (VRT) can benefit patients with a variety of balance and vestibular disorders. This expanding field requires knowledgeable and experienced therapists; however, the practice and experience of those providing this care may vary greatly. The purpose of this study was to analyze variations in training and practice patterns among practicing vestibular rehabilitation therapists. Case-controlled cohort study. Investigation of outpatient physical therapy and audiology practices that offer vestibular rehabilitation conducted by a tertiary academic referral center. Questionnaire-based investigation of level of training in vestibular disorders and therapy, practice patterns of vestibular rehabilitation, and referral sources for VRT patients. We identified 27 subjects within the state of Kentucky who practice vestibular rehabilitation and the questionnaire response rate was 63 %. Responses indicated that 53 % of respondents had no training in VRT during their professional degree program. Attendance of a course requiring demonstration of competence and techniques was 24 % of participants. The development of VRT certification was significantly more favored by those who attended such courses compared with those who did not (p = 0.01). 50 % of therapists have direct access to patients without physician referrals. There is a wide range of educational background and training among those practicing VRT. This variability in experience may affect care provided within some communities. Certification is not necessary for the practice of VRT but the development of certification is favored among some therapists to improve standardization of practice of this important specialty. PMID:25700790

  13. Vestibular effects of lidocaine intratympanic injection in rats.

    PubMed

    Lee, H H; Kim, M J; Jo, Y K; Kim, J Y; Han, G C

    2014-11-01

    When lidocaine is locally delivered into the inner ear, it rapidly paralyzes the peripheral vestibular afferent neurons and induces unilateral vestibular loss. The goals of this study were to explore the possibility of developing intratympanic injection (IT) of lidocaine as a modality for treating acute vertigo. To evaluate the minimum concentration required, latent time, action duration, and possibility of lidocaine IT readministration to the vestibular system, we compared the development of horizontal nystagmus after IT of 2, 4, 6, 8, and 10% lidocaine solutions in rats. To identify the induction of vestibular compensation, c-Fos-like protein expression was observed in the vestibular nucleus. Results of our investigation showed that lidocaine IT concentrations greater than 4% induced vestibular hyporeflexia in the injected ear. In order to induce hyporeflexia 4 and 6% lidocaine solutions could also be repeatedly injected. Regardless of concentration, effects of the lidocaine IT dissipated gradually over time. Our findings could be used to develop novel methods for symptom control in vestibular disorder patients. PMID:24505049

  14. Galvanic vestibular stimulation speeds visual memory recall.

    PubMed

    Wilkinson, David; Nicholls, Sophie; Pattenden, Charlotte; Kilduff, Patrick; Milberg, William

    2008-08-01

    The experiments of Alessandro Volta were amongst the first to indicate that visuo-spatial function can be altered by stimulating the vestibular nerves with galvanic current. Until recently, the beneficial effects of the procedure were masked by the high levels of electrical current applied, which induced nystagmus-related gaze deviation and spatial disorientation. However, several neuropsychological studies have shown that much weaker, imperceptible currents that do not elicit unpleasant side-effects can help overcome visual loss after stroke. Here, we show that visual processing in neurologically healthy individuals can also benefit from galvanic vestibular stimulation. Participants first learnt the names of eight unfamiliar faces and then after a short delay, answered questions from memory about how pairs of these faces differed. Mean correct reaction times were significantly shorter when sub-sensory, noise-enhanced anodal stimulation was administered to the left mastoid, compared to when no stimulation was administered at all. This advantage occurred with no loss in response accuracy, and raises the possibility that the procedure may constitute a more general form of cognitive enhancement. PMID:18584162

  15. Surgical approach to the superior vestibular nerve in guinea pigs.

    PubMed

    Hildesheimer, M; Muchnik, C; Rubinstein, M

    1987-12-01

    The superior vestibular nerve carries homo- and contra-lateral efferent fibers to the cochlea. The subarcuate fossa, a tube-like structure in the temporal bone of the guinea pig, can be used to reach the superior vestibular nerve at the level of the internal acoustic meatus. Normally, this structure accommodates the dorsal and ventral floccular extension of the cerebellum. This technique has several advantages. Firstly, a reduced cranial opening is necessary; secondly, less cerebellar tissue is sacrificed. Then there is the relative insulation of the operative field, and finally, it presents a straight guide to the internal auditory meatus and vestibular nerve. PMID:3446675

  16. Stochastic neurodynamics

    Microsoft Academic Search

    Kunio Yasue; Mari Jibu; Tetsuya Misawa; Jean-Claude Zambrini

    1988-01-01

    Stochastic dynamics of relative membrane potential in the neural network is investigated. It is called stochastic neurodynamics. The least action principle for stochastic neurodynamics is assumed, and used to derive the fundamental equation. It is called a neural wave equation. A solution of the neural wave equation is called a neural wave function and describes stochastic neurodynamics completely. Linear superposition

  17. Internal models of self-motion: computations that suppress vestibular reafference in early vestibular processing

    Microsoft Academic Search

    Kathleen E. CullenJessica; Jessica X. Brooks; Mohsen Jamali; Jerome Carriot; Corentin Massot

    2011-01-01

    In everyday life, vestibular sensors are activated by both self-generated and externally applied head movements. The ability\\u000a to distinguish inputs that are a consequence of our own actions (i.e., active motion) from those that result from changes\\u000a in the external world (i.e., passive or unexpected motion) is essential for perceptual stability and accurate motor control.\\u000a Recent work has made progress

  18. A vestibular prosthesis with highly-isolated parallel multichannel stimulation.

    PubMed

    Jiang, Dai; Cirmirakis, Dominik; Demosthenous, Andreas

    2015-02-01

    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

  19. [Vestibular paroxysmia: clinical study and treatment of eight patients].

    PubMed

    Kanashiro, Aline Mizuta Kozoroski; Alexandre, Paula Levatti; Pereira, Cristiana Borges; Melo, Antonio Carlos de Paiva; Scaff, Milberto

    2005-09-01

    Vestibular paroxysmia is a syndrome of cross-compression of the VIII cranial nerve and was first described by Jannetta who used the term "disabling positional vertigo". This syndrome is characterized by brief attacks of vertigo, tinnitus, vestibular and auditory deficits. MRI may show the VIII nerve compression from vessels in the posterior fossa, such as the basilar, vertebral, anterior-inferior cerebellar or the posterior-inferior cerebellar arteries. Vestibular paroxysmia may be treated either with medical therapy, such as carbamazepine, phenytoin or gabapentin or with the microvascular decompression of the VIII nerve. This study describes eight patients with vestibular paroxysmia. Four of them showed also clinical signs suggesting cross-compression of the V and/or VII nerve. Seven patients treated with carbamazepine had significant improvement of vertigo and tinnitus. PMID:16172715

  20. Assessment of clinical data of nonlinear stochastic deconvolution versus block-circulant singular value decomposition for quantitative dynamic susceptibility contrast magnetic resonance imaging.

    PubMed

    Peruzzo, Denis; Zanderigo, Francesca; Bertoldo, Alessandra; Pillonetto, Gianluigi; Cosottini, Mirco; Cobelli, Claudio

    2011-09-01

    Dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) allows the noninvasive assessment of brain hemodynamics alterations by quantifying, via deconvolution, the cerebral blood flow (CBF) and mean transit time (MTT). Singular value decomposition (SVD) and block-circulant SVD (cSVD) are the most widely adopted deconvolution method, although they bear some limitations, including unphysiological oscillations in the residue function and bias in the presence of delay and dispersion between the tissue and the arterial input function. A nonlinear stochastic regularization (NSR) has been proposed, which performs better than SVD and cSVD on simulated data both in the presence and absence of dispersion. Moreover, NSR allows to quantify the dispersion level. Here, cSVD and NSR are compared for the first time on a group of nine patients with severe atherosclerotic unilateral stenosis of internal carotid artery before and after carotid stenting to investigate the effect of arterial dispersion. According to region of interest-based analysis, NSR characterizes the pathologic tissue more accurately than cSVD, thus improving the quality of the information provided to physicians for diagnosis. In fact, in 7 (78%) of the 9 subjects, CBF and MTT maps provided by NSR allow to correctly identify the pathologic hemisphere to the physician. Moreover, by emphasizing the difference between pathologic and healthy tissues, NSR may be successfully used to monitor the subject's recovery after the treatment and/or surgery. NSR also generates dispersion level and non-dispersed CBF and MTT maps. The dispersion level provides information on CBF and MTT estimates reliability and may also be used as a clinical indicator of pathological tissue state complementary to CBF and MTT, thus increasing the clinical information provided by DSC-MRI analysis. PMID:21616625