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1

Improving balance function using vestibular stochastic resonance: optimizing stimulus characteristics  

Microsoft Academic Search

Stochastic resonance (SR) is a phenomenon whereby the response of a non-linear system to a weak periodic input signal is optimized\\u000a by the presence of a particular non-zero level of noise. Stochastic resonance using imperceptible stochastic vestibular electrical\\u000a stimulation, when applied to normal young and elderly subjects, has been shown to significantly improve ocular stabilization\\u000a reflexes in response to whole-body

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

2011-01-01

2

Functional stochastic resonance in human baroreflex induced by 1/f-type noisy galvanic vestibular stimulation  

NASA Astrophysics Data System (ADS)

We hypothesized that 1/f noise is more beneficial than the conventional white noise in optimizing the brain's response to a weak input signal, and showed that externally added 1/f noise outperforms white noise in sensitizing human baroreflex centers in the brain. We examined the compensatory heart rate response to weak periodic signal introduced at the venous blood pressure receptor, while adding either 1/f or white noise with the same variance to the brain stem by electrically stimulating the bilateral vestibular afferents cutaneously. This stochastic galvanic vestibular stimulation, activating the vestibulo-sympathetic pathway in the brain stem, optimized covariance between weak input signals and the heart rate responses both with 1/f and white noise. Further, the optimal noise level with 1/f noise was significantly lower than that with white noise, suggesting the functional benefit of 1/f noise for the neuronal information transfer in the brain.

Soma, Rika; Kwak, Shin; Yamamoto, Yoshiharu

2003-05-01

3

Stochastic resonance  

NASA Astrophysics Data System (ADS)

Over the last two decades, stochastic resonance has continuously attracted considerable attention. The term is given to a phenomenon that is manifest in nonlinear systems whereby generally feeble input information (such as a weak signal) can be be amplified and optimized by the assistance of noise. The effect requires three basic ingredients: (i) an energetic activation barrier or, more generally, a form of threshold; (ii) a weak coherent input (such as a periodic signal); (iii) a source of noise that is inherent in the system, or that adds to the coherent input. Given these features, the response of the system undergoes resonance-like behavior as a function of the noise level; hence the name stochastic resonance. The underlying mechanism is fairly simple and robust. As a consequence, stochastic resonance has been observed in a large variety of systems, including bistable ring lasers, semiconductor devices, chemical reactions, and mechanoreceptor cells in the tail fan of a crayfish. In this paper, the authors report, interpret, and extend much of the current understanding of the theory and physics of stochastic resonance. They introduce the readers to the basic features of stochastic resonance and its recent history. Definitions of the characteristic quantities that are important to quantify stochastic resonance, together with the most important tools necessary to actually compute those quantities, are presented. The essence of classical stochastic resonance theory is presented, and important applications of stochastic resonance in nonlinear optics, solid state devices, and neurophysiology are described and put into context with stochastic resonance theory. More elaborate and recent developments of stochastic resonance theory are discussed, ranging from fundamental quantum properties-being important at low temperatures-over spatiotemporal aspects in spatially distributed systems, to realizations in chaotic maps. In conclusion the authors summarize the achievements and attempt to indicate the most promising areas for future research in theory and experiment.

Gammaitoni, Luca; Hänggi, Peter; Jung, Peter; Marchesoni, Fabio

1998-01-01

4

Energetics of stochastic resonance  

NASA Astrophysics Data System (ADS)

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.

Jung, Peter; Marchesoni, Fabio

2011-12-01

5

Experimental investigation of stochastic resonance  

NASA Astrophysics Data System (ADS)

We report the experimental evidence of Stochastic Resonance in the polarized emission of a semiconductor laser. We give for the first time in a real system a complete characterization of the phenomenon based on the residence times probability density, with quantitative agreement with existing theories. By using an accurate choice of the indicator, we also provide a clear evidence of the bona fide resonance. Moreover, we are able to introduce and investigate for the first time a Three-state Stochastic Resonance. .

Barbay, Sylvain; Giacomelli, Giovanni; Marin, Francesco; Rabbiosi, Ivan; Voignier, Vincent

2000-02-01

6

Stochastic resonance in electrical circuits. I. Conventional stochastic resonance  

Microsoft Academic Search

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

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

1999-01-01

7

Stochastic resonance on a circle  

SciTech Connect

We describe a new realization of stochastic resonance, applicable to a broad class of systems, based on an underlying excitable dynamics with deterministic reinjection. A simple but general theory of such single-trigger'' systems is compared with analog simulations of the Fitzhugh-Nagumo model, as well as experimental data obtained from stimulated sensory neurons in the crayfish.

Wiesenfeld, K. (School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)); Pierson, D.; Pantazelou, E.; Dames, C.; Moss, F. (Department of Physics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States))

1994-04-04

8

Stochastic resonance on a circle  

NASA Astrophysics Data System (ADS)

We describe a new realization of stochastic resonance, applicable to a broad class of systems, based on an underlying excitable dynamics with deterministic reinjection. A simple but general theory of such ``single-trigger'' systems is compared with analog simulations of the Fitzhugh-Nagumo model, as well as experimental data obtained from stimulated sensory neurons in the crayfish.

Wiesenfeld, Kurt; Pierson, David; Pantazelou, Eleni; Dames, Chris; Moss, Frank

1994-04-01

9

Pitch sensation involves stochastic resonance.  

PubMed

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

Martignoli, Stefan; Gomez, Florian; Stoop, Ruedi

2013-09-18

10

Stochastic resonant memory storage device.  

PubMed

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

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

2001-08-06

11

Stochastic resonance in threshold systems.  

PubMed

We consider signal processing in simple threshold systems with nonstationary additive and/or multiplicative noise. A discrete-time process with a small periodical signal masked by noise represents an input. The systems convert sampled input data to a nonstationary random point event flow carrying some information on an input signal. As it is shown in our previous study [M.M. Alibegov, Astron. Lett. 22, 564 (1996)], the Rayleigh spectral function of a random point event train estimates a signal-to-noise ratio (SNR) at selected frequencies. Based on these results, we compute a system response at signal frequencies as a function of threshold and input noise intensity. The threshold systems are shown to reveal stochastic resonance (SR), i.e., output SNR exhibits a maximum at resonant noise intensity (intensities) and threshold(s) at rather common conditions. We show that SR and Rayleigh spectral technique allow us to carry out numerical signal detection in data sets with noise. PMID:11969434

Alibegov, M M

1999-05-01

12

Stochastic resonance in a bistable geodynamo model  

Microsoft Academic Search

Recently a signal with a period of 100 kyr in the distribution of residence times between reversals of the geomagnetic field has been suggested as signature of stochastic resonance. Here we test this suggestion by applying periodic modulations to a model of the geodynamo as a bistable oscillator, where stochastic fluctuations of the induction effect (multiplicative noise) lead to random

S. Lorito; D. Schmitt; G. Consolini; P. De Michelis

2005-01-01

13

Stochastic resonance in optical bistable systems  

Microsoft Academic Search

We study the response of a noise-driven absorptive optical bistable system which is subjected to deterministic periodic perturbations of the incident light intensity. This system is characterized by state-dependent noise which in turn can strongly enhance-via stochastic resonance-the response due to the external periodic perturbation. We demonstrate that the condition for stochastic resonance sensitively depends on the shape of the

Roland Bartussek; Peter Hänggi; Peter Jung

1994-01-01

14

Behavioral Stochastic Resonance within the Human Brain  

NASA Astrophysics Data System (ADS)

We provide the first evidence that stochastic resonance within the human brain can enhance behavioral responses to weak sensory inputs. We asked subjects to adjust handgrip force to a slowly changing, subthreshold gray level signal presented to their right eye. Behavioral responses were optimized by presenting randomly changing gray levels separately to the left eye. The results indicate that observed behavioral stochastic resonance was mediated by neural activity within the human brain where the information from both eyes converges.

Kitajo, Keiichi; Nozaki, Daichi; Ward, Lawrence M.; Yamamoto, Yoshiharu

2003-05-01

15

Stochastic resonance in optical bistable systems  

NASA Astrophysics Data System (ADS)

We study the response of a noise-driven absorptive optical bistable system which is subjected to deterministic periodic perturbations of the incident light intensity. This system is characterized by state-dependent noise which in turn can strongly enhance-via stochastic resonance-the response due to the external periodic perturbation. We demonstrate that the condition for stochastic resonance sensitively depends on the shape of the bistable generalized potential (symmetric or asymmetric). Furthermore, the generation of higher harmonics is studied in the presence of fluctuations. We report on a novel phase-sensitive resonance phenomenon which virtually eliminates the higher harmonics and thus allows for distortion-free amplification of signals via stochastic resonance.

Bartussek, Roland; Hänggi, Peter; Jung, Peter

1994-05-01

16

Stochastic resonance in binocular rivalry  

Microsoft Academic Search

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

Yee-Joon Kim; Marcia Grabowecky; Satoru Suzuki

2006-01-01

17

Stochastic resonance of the visually evoked potential  

Microsoft Academic Search

Stochastic resonance refers to the enhancement of a signal by the addition of a small amount of noise and its degradation by a larger amount of noise. It occurs in a variety of physical systems including neuronal systems. However, its demonstration in neuronal systems has so far been limited to single-dimensional systems such as a single mechanoreceptor. We report here

R. Srebro; P. Malladi

1999-01-01

18

Stochastic resonance in photonic crystal growth  

Microsoft Academic Search

We study the role of noise during the growth process of opal-based photonic crystals, and demonstrate that noise significantly improves their structural properties. We observe a stochastic resonance-like behaviour, where the ordering of the resulting structure improves up to a certain optimal noise level and then deteriorates for larger noise volumes. This demonstrates that noise can have a nontrivial effect

Andreas Amann; Worawut Khunsin; Gudrun Kocher; Clivia M. Sotomayor Torres; Eoin P. O'Reilly

2007-01-01

19

Stochastic resonance in a bistable ring laser  

SciTech Connect

Stochastic resonance was recently observed in a bistable ring laser. It isa phenomenon in which the response of a bistable system to a periodicmodulation is enhanced by the injection of noise along with the modulation. Sofar, comparisons of the experimental observations with theory have been madeonly for models that are much simplified compared with the more realistictwo-mode equations that describe the ring laser. We report here the results of numerical simulations of the stochastic differential equations for the laser with periodic modulation of the asymmetry between the two modes and injected noise. The simulations reveal the phenomenon of stochastic resonance in a manner closely resembling the experimental observations. The appearance of second-harmonic frequencies in the output power spectrum and the role of the colored nature of the pump laser noise are studied. Finally, we discuss the relation of the recent experimental measurements of hysteresis in a ring dye laser by Gage and Mandel (J. Opt. Soc. Am. B (to be published)) to the observation of stochastic resonance.

Vemuri, G.; Roy, R.

1989-05-01

20

From stochastic resonance to brain waves  

NASA Astrophysics Data System (ADS)

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

Balázsi, G.; Kish, L. B.

2000-01-01

21

Geometric stochastic resonance in a double cavity  

NASA Astrophysics Data System (ADS)

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.

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

2011-07-01

22

Fractional Brownian motors and stochastic resonance.  

PubMed

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

Goychuk, Igor; Kharchenko, Vasyl

2012-05-22

23

Stochastic resonance in liquid membrane oscillator  

NASA Astrophysics Data System (ADS)

The oil/water liquid membrane oscillator which has been intensively investigated in recent years is generally considered a promising model for excitable biomembranes. The present work deals with the stochastic resonance (SR) phenomena liquid membrane oscillators with the model proposed by Yoshikawa, and the mechanism of SR and some interesting behaviors are also discussed. When SR occurs, the input signal is greatly amplified with the cooperation of noise and the output signal-to-noise ratio is also dramatically enhanced. We consider SR as a possible functional mechanism of some sensory cells.

Zuo, Xiaobing; Hou, Zhonghuai; Xin, Houwen

1998-10-01

24

Stochastic resonance enhanced by dichotomic noise in a bistable system  

SciTech Connect

We study linear responses of a stochastic bistable system driven by dichotomic noise to a weak periodic signal. We show that the effect of stochastic resonance can be greatly enhanced in comparison with the conventional case when dichotomic forcing is absent, that is, both the signal-to-noise ratio and the spectral power amplification reach much greater values than in the standard stochastic resonance setup. (c) 2000 The American Physical Society.

Rozenfeld, Robert [Institute for Physics, Humboldt University at Berlin, D-10115, Berlin, (Germany); Neiman, Alexander [Center for Neurodynamics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States); Schimansky-Geier, Lutz [Institute for Physics, Humboldt University at Berlin, D-10115, Berlin, (Germany)

2000-09-01

25

Stochastic resonance between propagating extended attractors  

SciTech Connect

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.

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

26

Stochastic Resonance Crossovers in Complex Networks  

PubMed Central

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.

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

2012-01-01

27

Parameter dependence of stochastic resonance in the stochastic Hodgkin-Huxley neuron  

Microsoft Academic Search

Recently, the phenomena of stochastic resonance (SR) have attracted much attention in the studies of the excitable systems under inherent noise, in particular, nervous systems. We study SR in a stochastic Hodgkin-Huxley neuron under Ornstein-Uhlenbeck noise and periodic stimulus, focusing on the dependence of properties of SR on stimulus parameters. We find that the dependence of the critical forcing amplitude

Sang-Gui Lee; Seunghwan Kim

1999-01-01

28

Delayed stochastic resonance with 1-D chain of binary elements  

NASA Astrophysics Data System (ADS)

We discuss a simple model of 1-dimensional chain of binary stochastic elements with delayed interaction. Each element makes transitions between its two states, with probabilities which depends on the fixed-interval-past state of the preceding element in the chain. We show that rather regular spiking behavior emerges with suitably tuned parameters. This can be seen as a stochastic resonance just from noise and delay coupling alone without external oscillatory signals. This phenomena is analyzed theoretically and its applications to communication systems or biological systems are discussed. This is an extension of previous woks on delayed stochastic resonance with single[1] and two units [2]. [1] Toru Ohira and Yuzuru Sato, "Resonance with noise and delay", PRL vol 82, pp.2811-2815 (1999). [2] Toru Ohira and Yuzuru Sato, "Resonance in Delayed Stochastic Dynamics", Statistical Physics, (Tokuyama and Stanley, eds.) , AIP conference Proceedings 519, pp. 628-634 (2000).

Ohira, Toru

2001-03-01

29

Coherent signal amplification in bistable nanomechanical oscillators by stochastic resonance  

NASA Astrophysics Data System (ADS)

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.

Badzey, Robert L.; Mohanty, Pritiraj

2005-10-01

30

Information transmission in parallel threshold arrays: suprathreshold stochastic resonance.  

PubMed

The information transmitted through a parallel summing array of noisy threshold elements with a common threshold is considered. In particular, using theoretical and numerical analysis, a recently reported [N. G. Stocks, Phys. Rev. Lett. 84, 2310 (2000)] form of stochastic resonance, termed suprathreshold stochastic resonance (SSR), is studied in detail. SSR is observed to occur in arrays with two or more elements and, unlike stochastic resonance (SR) in a single element, gives rise to noise-induced information gains that occur independent of the setting of the threshold or the size of the signal. The transmitted information is maximized when all thresholds are set to coincide with the signal mean. In this situation, and for large arrays, the noise can enhance performance up to approximately half the theoretical noiseless channel capacity. The theory is tested against digital simulation. PMID:11308826

Stocks, N G

2001-03-28

31

Spatiotemporal Stochastic Resonance and its consequences in a neural system  

NASA Astrophysics Data System (ADS)

Biological neurons are good examples of a threshold device-this is why neural systems are in the focus when looking for realization of Stochastic Resonance (SR) and Spatiotemporal Stochastic Resonance (STSR) phenomena. There are two different ways to simulate neural systems-one based on differential equations, the other based on a simple threshold model. In this talk the effect of noise on neural systems will be discussed using both ways of modelling. The results so far suggest that SR and STSR do occur in models of neural systems. However, how significant is the role played by these phenomena and what implications might they have on neurobiology is still a question. .

Balázsi, Gábor; Kiss, László B.; Moss, Frank E.

2000-03-01

32

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

PubMed

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

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

2011-09-29

33

Stochastic resonance as an emergent property of neural networks  

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

34

Enhanced Vibrational Energy Harvesting Using Non-linear Stochastic Resonance  

Microsoft Academic Search

Stochastic resonance has seen wide application in the physical sciences as a tool to understand weak signal ampliflcation by noise. However, this apparently counter- intuitive phenomenon does not appear to have been exploited as a tool to enhance vibrational energy harvesting. In this note we demonstrate that by adding periodic forcing to a vibrationally excited energy harvesting mechanism, the power

C. R. McInnes; D. G. Gorman; M. P. Cartmell

2008-01-01

35

Stochastic resonance in a model neuron with reset  

Microsoft Academic Search

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.

Hans E. Plesser; Shigeru Tanaka

1997-01-01

36

Stochastic Resonance Modulates Neural Synchronization within and between Cortical Sources  

Microsoft Academic Search

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

Lawrence M. Ward; Shannon E. Maclean; Aaron Kirschner; Pedro Antonio Valdes-Sosa

2010-01-01

37

Stochastic resonance in the Weidlich model of public opinion formation  

NASA Astrophysics Data System (ADS)

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.

Babinec, Peter

1997-02-01

38

Sensor fusion enhancement via optimized stochastic resonance at local sensors  

Microsoft Academic Search

This paper considers the decentralized fusion problem involving local sensor detection as well as the fusion of decisions transmitted over non-ideal transmission channels in a wireless sensor network. Prime emphasis is given to the enhancement of several fusion rules using a recently developed stochastic resonance methodology applied at the local sensors. Further, it is shown that the optimal form of

Bin Liu; S. Iyengar; Hao Chen; J. H. Michels; P. K. Varshney

2007-01-01

39

Stochastic Resonance of a General Relativistic Accretion Disk  

NASA Astrophysics Data System (ADS)

Based on a generalized Langevin equation, we consider a full general relativistic model to describe the vertical oscillations of particles in accretion disks around compact astrophysical objects, and calculate oscillating luminosity and power spectral density (PSD) of an accretion disk. The influences of the friction parameter ?, spin parameter a* and mass M of the center compact object on the stochastic resonance (SR) in PSD curves are discussed. The results show that a large spin parameter a* can enhance the SR phenomenon, but the larger the ? or M is, the weaker the SR phenomenon becomes. In addition, our simulated PSD curves of the output luminosity of stochastically oscillating disk have the same profile as the observed PSD of x-ray binaries, and the resonance peak in the PSD curve can interpret the quasi-periodic oscillations at the same time.

Wang, Zhi-Yun; Chen, Pei-Jie; Zhang, Liang-Ying

2013-09-01

40

Stochastic resonance in hybrid scale-free neuronal networks  

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

41

Effects of Colored Noise on Stochastic Resonance in Sensory Neurons  

Microsoft Academic Search

Noise can assist neurons in the detection of weak signals via a mechanism known as stochastic resonance (SR). We demonstrate experimentally that SR-type effects can be obtained in rat sensory neurons with white noise, 1\\/f noise, or 1\\/f2 noise. For low-frequency input noise, we show that the optimal noise intensity is the lowest and the output signal-to-noise ratio the highest

Daichi Nozaki; Douglas J. Mar; Peter Grigg; James J. Collins

1999-01-01

42

Stochastic resonance in psychophysics and in animal behavior  

Microsoft Academic Search

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

Lawrence M. Ward; Alexander Neiman; Frank Moss

2002-01-01

43

Stochastic resonance in a locally excited system of bistable oscillators  

NASA Astrophysics Data System (ADS)

Stochastic resonance is studied in a one-dimensional array of overdamped bistable oscillators in the presence of a local subthreshold periodic perturbation. The system can be treated as an ensemble of pseudospins tending to align parallel which are driven dynamically by an external periodic magnetic field. The oscillators are subjected to a dynamic white noise as well as to a static topological disorder. The latter is quantified by the fraction of randomly added long-range connections among ensemble elements. In the low connectivity regime the system displays an optimal global stochastic resonance response if a small-world network is formed. In the mean-field regime we explain strong changes in the dynamic disorder strength provoking a maximal stochastic resonance response via the variation of fraction of long-range connections by taking into account the ferromagnetic-paramagnetic phase transition of the pseudospins. The system size analysis shows only quantitative power-law type changes on increasing number of pseudospins.

Gosak, M.; Perc, M.; Kralj, S.

2011-04-01

44

Escape process and stochastic resonance under noise intensity fluctuation  

NASA Astrophysics Data System (ADS)

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

Hasegawa, Yoshihiko; Arita, Masanori

2011-09-01

45

Cyclotron resonance effects on stochastic acceleration of light ionospheric ions  

NASA Astrophysics Data System (ADS)

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

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

1982-09-01

46

Stochastic resonance in a periodically modulated dissipative nuclear dynamics  

SciTech Connect

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.

Berezovoy, V.P. [and others

2001-02-01

47

Stochastic Dipolar Recoupling in Nuclear Magnetic Resonance of Solids  

SciTech Connect

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 system000.

Tycko, Robert [Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520 (United States)

2007-11-02

48

Information gain in an optical bistable system by stochastic resonance.  

PubMed

We have shown an experimental demonstration of information gain due to the stochastic resonance in an optical bistable system, that is, information hidden in the input wave form appears in the output of a nonlinear system when the input noise amplitude is adequate. The optical bistable system is a hybrid type comprising a LiNbO3 crystal with an electric feedback loop, and the input of the system is the sum of a binary bit series and a Gaussian colored noise. The information gain is proved to be prominent when the noise cutoff frequency is larger than the bit rate. PMID:16241194

Misono, M; Kohmoto, T; Kunitomo, M; Fukuda, Y

2003-06-06

49

Pulsar State Switching from Markov Transitions and Stochastic Resonance  

NASA Astrophysics Data System (ADS)

Markov processes are shown to be consistent with metastable states seen in pulsar phenomena, including intensity nulling, pulse-shape mode changes, subpulse drift rates, spin-down rates, and X-ray emission, based on the typically broad and monotonic distributions of state lifetimes. Markovianity implies a nonlinear magnetospheric system in which state changes occur stochastically, corresponding to transitions between local minima in an effective potential. State durations (though not transition times) are thus largely decoupled from the characteristic timescales of various magnetospheric processes. Dyadic states are common but some objects show at least four states with some transitions forbidden. Another case is the long-term intermittent pulsar B1931+24 that has binary radio-emission and torque states with wide, but non-monotonic duration distributions. It also shows a quasi-period of 38 ± 5 days in a 13 yr time sequence, suggesting stochastic resonance in a Markov system with a forcing function that could be strictly periodic or quasi-periodic. Nonlinear phenomena are associated with time-dependent activity in the acceleration region near each magnetic polar cap. The polar-cap diode is altered by feedback from the outer magnetosphere and by return currents from the equatorial region outside the light cylinder that may also cause the neutron star to episodically charge and discharge. Orbital perturbations of a disk or current sheet provide a natural periodicity for the forcing function in the stochastic-resonance interpretation of B1931+24. Disk dynamics may introduce additional timescales in observed phenomena. Future work can test the Markov interpretation, identify which pulsar types have a propensity for state changes, and clarify the role of selection effects.

Cordes, J. M.

2013-09-01

50

Effects of adaptive coupling on stochastic resonance of small-world networks  

NASA Astrophysics Data System (ADS)

The phenomenon of stochastic resonance in networks with small-world connectivity is investigated when the coupling strength is adaptive. The effects of the fixed and adaptive couplings on stochastic resonance of the system are discussed. It is found that the resonance is a monotonically increasing function of the adaptive coupling strength, while there is a peak when the coupling strength is fixed. The resonance for the adaptive coupling can reach a much larger value than that for fixed coupling.

Wu, Dan; Zhu, Shiqun; Luo, Xiaoqin; Wu, Liang

2011-08-01

51

Effects of adaptive coupling on stochastic resonance of small-world networks.  

PubMed

The phenomenon of stochastic resonance in networks with small-world connectivity is investigated when the coupling strength is adaptive. The effects of the fixed and adaptive couplings on stochastic resonance of the system are discussed. It is found that the resonance is a monotonically increasing function of the adaptive coupling strength, while there is a peak when the coupling strength is fixed. The resonance for the adaptive coupling can reach a much larger value than that for fixed coupling. PMID:21928944

Wu, Dan; Zhu, Shiqun; Luo, Xiaoqin; Wu, Liang

2011-08-02

52

Delay-induced multiple stochastic resonances on scale-free neuronal networks  

NASA Astrophysics Data System (ADS)

We study the effects of periodic subthreshold pacemaker activity and time-delayed coupling on stochastic resonance over scale-free neuronal networks. As the two extreme options, we introduce the pacemaker, respectively, to the neuron with the highest degree and to one of the neurons with the lowest degree within the network, but we also consider the case when all neurons are exposed to the periodic forcing. In the absence of delay, we show that an intermediate intensity of noise is able to optimally assist the pacemaker in imposing its rhythm on the whole ensemble, irrespective to its placing, thus providing evidences for stochastic resonance on the scale-free neuronal networks. Interestingly thereby, if the forcing in form of a periodic pulse train is introduced to all neurons forming the network, the stochastic resonance decreases as compared to the case when only a single neuron is paced. Moreover, we show that finite delays in coupling can significantly affect the stochastic resonance on scale-free neuronal networks. In particular, appropriately tuned delays can induce multiple stochastic resonances independently of the placing of the pacemaker, but they can also altogether destroy stochastic resonance. Delay-induced multiple stochastic resonances manifest as well-expressed maxima of the correlation measure, appearing at every multiple of the pacemaker period. We argue that fine-tuned delays and locally active pacemakers are vital for assuring optimal conditions for stochastic resonance on complex neuronal networks.

Wang, Qingyun; Perc, Matjaž; Duan, Zhisheng; Chen, Guanrong

2009-06-01

53

Optimization of Stochastic-Resonance based Schmitt Trigger through parametric analysis  

Microsoft Academic Search

Stochastic Resonance is a phenomenon where noise, instead of degrading the system's SNR, acts as an amplifying force upon interacting with weak signals. This behavior of noise is observed in various nonlinear systems and a few naturally occurring phenomena. The dynamics of Stochastic Resonance are well established for a nonlinear bistable system. Schmitt Trigger is an example of such a

Muhammad Safian Adeel; Umar Rashid

2009-01-01

54

Delay-induced multiple stochastic resonances on scale-free neuronal networks.  

PubMed

We study the effects of periodic subthreshold pacemaker activity and time-delayed coupling on stochastic resonance over scale-free neuronal networks. As the two extreme options, we introduce the pacemaker, respectively, to the neuron with the highest degree and to one of the neurons with the lowest degree within the network, but we also consider the case when all neurons are exposed to the periodic forcing. In the absence of delay, we show that an intermediate intensity of noise is able to optimally assist the pacemaker in imposing its rhythm on the whole ensemble, irrespective to its placing, thus providing evidences for stochastic resonance on the scale-free neuronal networks. Interestingly thereby, if the forcing in form of a periodic pulse train is introduced to all neurons forming the network, the stochastic resonance decreases as compared to the case when only a single neuron is paced. Moreover, we show that finite delays in coupling can significantly affect the stochastic resonance on scale-free neuronal networks. In particular, appropriately tuned delays can induce multiple stochastic resonances independently of the placing of the pacemaker, but they can also altogether destroy stochastic resonance. Delay-induced multiple stochastic resonances manifest as well-expressed maxima of the correlation measure, appearing at every multiple of the pacemaker period. We argue that fine-tuned delays and locally active pacemakers are vital for assuring optimal conditions for stochastic resonance on complex neuronal networks. PMID:19566247

Wang, Qingyun; Perc, Matjaz; Duan, Zhisheng; Chen, Guanrong

2009-06-01

55

Stochastic Resonance in a Linear Fractional Langevin Equation  

NASA Astrophysics Data System (ADS)

The fractional Langevin equation is derived from the generalized Langevin equation driven by the additive fractional Gaussian noise. We investigate the stochastic resonance (SR) phenomenon in the underdamped linear fractional Langevin equation under the external periodic force and multiplicative symmetric dichotomous noise. Applying the Shapiro-Loginov formula and the Laplace transform technique, we obtain the exact expressions of the amplitude and signal-to-noise ratio (SNR) of the system. By studying the impacts of the driving frequency and the noise parameters, we find the non-monotonic behaviors of the output amplitude and SNR. The results indicate that the bona fide SR, conventional SR and the wide sense of SR phenomena occur in the proposed linear fractional system.

Zhong, Suchuan; Wei, Kun; Gao, Shilong; Ma, Hong

2013-03-01

56

Cost-effective initial screening for vestibular schwannoma: auditory brainstem response or magnetic resonance imaging?  

Microsoft Academic Search

ObjectiveOur goal was to determine the cost-effectiveness of including auditory brainstem response (ABR) testing in a screening protocol for the diagnosis of vestibular schwannoma (VS) in patients with asymmetric auditory symptoms at the Christian Medical College and Hospital, Vellore, India, where, commonly, patients with VS have tumors greater than 2 cm at the time of diagnosis.

Vedantam Rupa; Anand Job; Mercy George; Vedantam Rajshekhar

2003-01-01

57

Stochastic resonance for information flows on hierarchical networks  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

58

Resonant-Separatrix Webs in Stochastic Layers of the Twin-Well Duffing Oscillator  

Microsoft Academic Search

The excitation strength for the onset of a new resonant-separatrix in the stochastic layer of the Duffing oscillator is predicted through the energy change in minimum and maximum energy spectra. The widths of stochastic layers are estimated through the use of the maximum and minimum energy which can be measured experimentally. The energy spectrum approach, rather than the Poincaré mapping

Albert C. J. Luo; Keqin Gu; Ray P. S. Han

1999-01-01

59

Capacity Bounds and Stochastic Resonance for Binary Input Binary Output Channels.  

National Technical Information Service (NTIS)

In this paper, we discuss the threshold based stochastic resonance behavior of binary input, binary output discrete memoryless channels. We follow the basic model of Chapeau-Blondeau where he showed how the addition of external Gaussian noise could enhanc...

D. L. Kang I. S. Moskowitz P. Cotae P. N. Safier

2012-01-01

60

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

Microsoft Academic Search

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

Mark D. McDonnell; Derek Abbott

2009-01-01

61

Stochastic Resonance in crayfish hydrodynamic receptors stimulated with external noise  

NASA Astrophysics Data System (ADS)

Stochastic Resonance (SR) is a statistical process occurring only in nonlinear dynamical systems whereby a subthreshold coherent stimulus or signal can be enhanced by noise. The signal alone is too weak to cause a state change of the system. State changes are the carriers of information through the system. In the presence of random noise, however, the system can change state, more-or-less randomly, but with some degree of coherence with the signal. A measure of this coherence at the output shows a maximum at an optimal value of the noise intensity as the signature of SR. SR is the object of recent and continued experimental and theoretical research in statistical physics. While SR has been demonstrated in a variety of physical systems, it has not yet been discovered in any naturally occurring system. This paper was stimulated by the idea that the sensory nervous system might be an appropriate setting for a search for naturally occurring SR. The detection of weak stimuli, often in the presence of noise, is, after all, the first business of the sensory system. Moreover, the system is evolved, which admits the possibility that the process of natural selection might have resulted in an optimization with respect to the (inevitable) noise. This paper describes an experiment designed to observe SR in the mechanoreceptor cells of the crayfish Procambarus clarkii, shown on the left in Fig. 1, using external noise plus a weak coherent signal as the stimulus.

Douglass, J. K.; Wilkens, L. A.; Pantazelou, E.; Moss, F.

1993-08-01

62

Stochastic resonance in a superconducting Nb wire network  

NASA Astrophysics Data System (ADS)

We investigate a.c. flux dynamics in the anisotropic square network of superconducting Nb wires. Oscillating magnetic field is applied to the network at T< Tc and the telegraph noise caused by the jumps of the individual flux quanta between the network sites is registered locally with a Scanning Hall Probe microscope. Frequency of the observed flux jumps (local a.c. response) at any T ˜0.7-0.95)Tc can be maximized by tuning the driving frequency; the maximum response moves towards higher frequency when T is increased. Local noise spectra reveal 1/f^2 dependence of the spectral power density and dips at the second harmonic of the driving frequency that are typical for the stochastic resonance condition. We suggest that thermal noise in the system enhances its response to the periodic drive. Next, we observe formation of the ordered stripe-like flux patterns in the network due to the oscillating external field and discuss noise-assisted flux ordering.

Marchevsky, M.; Higgins, M. J.; Bhattacharya, S.

2004-03-01

63

COMMUNICATION: Stochastic resonance and the evolution of Daphnia foraging strategy  

NASA Astrophysics Data System (ADS)

Search strategies are currently of great interest, with reports on foraging ranging from albatrosses and spider monkeys to microzooplankton. Here, we investigate the role of noise in optimizing search strategies. We focus on the zooplankton Daphnia, which move in successive sequences consisting of a hop, a pause and a turn through an angle. Recent experiments have shown that their turning angle distributions (TADs) and underlying noise intensities are similar across species and age groups, suggesting an evolutionary origin of this internal noise. We explore this hypothesis further with a digital simulation (EVO) based solely on the three central Darwinian themes: inheritability, variability and survivability. Separate simulations utilizing stochastic resonance (SR) indicate that foraging success, and hence fitness, is maximized at an optimum TAD noise intensity, which is represented by the distribution's characteristic width, ?. In both the EVO and SR simulations, foraging success is the criterion, and the results are the predicted characteristic widths of the TADs that maximize success. Our results are twofold: (1) the evolving characteristic widths achieve stasis after many generations; (2) as a hop length parameter is changed, variations in the evolved widths generated by EVO parallel those predicted by SR. These findings provide support for the hypotheses that (1) ? is an evolved quantity and that (2) SR plays a role in evolution.

Dees, Nathan D.; Bahar, Sonya; Moss, Frank

2008-12-01

64

Stochastic resonance and the evolution of Daphnia foraging strategy.  

PubMed

Search strategies are currently of great interest, with reports on foraging ranging from albatrosses and spider monkeys to microzooplankton. Here, we investigate the role of noise in optimizing search strategies. We focus on the zooplankton Daphnia, which move in successive sequences consisting of a hop, a pause and a turn through an angle. Recent experiments have shown that their turning angle distributions (TADs) and underlying noise intensities are similar across species and age groups, suggesting an evolutionary origin of this internal noise. We explore this hypothesis further with a digital simulation (EVO) based solely on the three central Darwinian themes: inheritability, variability and survivability. Separate simulations utilizing stochastic resonance (SR) indicate that foraging success, and hence fitness, is maximized at an optimum TAD noise intensity, which is represented by the distribution's characteristic width, sigma. In both the EVO and SR simulations, foraging success is the criterion, and the results are the predicted characteristic widths of the TADs that maximize success. Our results are twofold: (1) the evolving characteristic widths achieve stasis after many generations; (2) as a hop length parameter is changed, variations in the evolved widths generated by EVO parallel those predicted by SR. These findings provide support for the hypotheses that (1) sigma is an evolved quantity and that (2) SR plays a role in evolution. PMID:19029598

Dees, Nathan D; Bahar, Sonya; Moss, Frank

2008-11-24

65

Stochastic resonance on a global atmospheric circulation model  

NASA Astrophysics Data System (ADS)

Seeking for alternative sources of the observed climatic variability, and in the spirit of both classic (Nicolis, 1982; Benzi et al., 1982) and recent work (Ganopolski and Rahmstorg, 2002; Vélez-Belch&{acute;i} et al., 2001), we have added a space-independent, Gaussian and uncorrelated stochastic perturbation with amplitude eta, to the temperature equation of a simplified atmospheric global circulation model, the so-called PUMA (Portable University Model of the Atmosphere) (Frisius et al., 1998; Pérez-Muñuzuri et al., 2003). In the latter model, diabatic processes are parameterized by a Newtonian cooling term with typical timescale ?_c, whose reference temperature profile T_R(?,?,?;t) (representing the ``equilibrium'' profile induced by solar heating) is given by T_R=overline{T}_R(?,?,?)+ hat{T}_R \\cos[(2pi/Tac)t+Pac]. We show that the time averages of several forecasting magnitudes (like temperature and horizontal vorticity) at a point on the 300 hPa surface, undergo a non-monotonic behavior with regard to eta. Moreover, the normalized variance R=sqrt{-^2}/ of the interval t_p between the passage at the point of cyclonic and anticyclonic circulation regions exhibits an ``anticoherence resonance'' effect, thus maximizing climatic variability for some intermediate value of eta. A theoretical explanation is advanced in terms of activated processes with competing time scales. begin{itemize} C. Nicolis, Tellus 34, 1 (1982); Benzi et al., Tellus 34, 10 (1982). A. Ganopolski and S. Rahmstorg, Phys. Rev. Lett. 88, 038501 (2002); P. Vélez-Belch&{acute;i} et al., Geophys. Res. Lett. 28, 2053 (2001). T. Frisius, F. Lunkeit, K. Fraedrich and I.N. James. Q.J.R. Meteorol. Soc. 124, 1019 (1998); V. Pérez-Muñuzuri et al. Nonlin. Proc. Geophys. (submitted) (2003).

Perez-Munuzuri, V.; Deza, R.; Fraedrich, K.; Kirk, E.; Lunkeit, F.

2003-04-01

66

Stochastic resonance in a non-Poissonian dichotomous process: a new analytical approach  

NASA Astrophysics Data System (ADS)

In this paper we present a new approach to evaluate the average of a function of a stochastic variable in the case of a non-Poissonian dichotomous process. We show that using a two-point correlation function approximation we can explore the asymptotic regime with great precision. We apply our approach to study the phenomenon of stochastic resonance. As an example we consider a resistor–capacitor circuit with a stochastic capacitance C and driven by a periodic voltage. We provide an analytical expression for the average charge in the stationary regime and we show that the amplitude of the average charge, and consequently of the average current, displays the phenomenon of stochastic resonance.

Bologna, Mauro; Chandía, Kristopher J.; Tellini, Bernardo

2013-07-01

67

Coherence resonance and stochastic synchronization in a nonlinear circuit near a subcritical Hopf bifurcation  

NASA Astrophysics Data System (ADS)

We analyze noise-induced phenomena in nonlinear dynamical systems near a subcritical Hopf bifurcation. We investigate qualitative changes of probability distributions (stochastic bifurcations), coherence resonance, and stochastic synchronization. These effects are studied in dynamical systems for which a subcritical Hopf bifurcation occurs. We perform analytical calculations, numerical simulations and experiments on an electronic circuit. For the generalized Van der Pol model we uncover the similarities between the behavior of a self-sustained oscillator characterized by a subcritical Hopf bifurcation and an excitable system. The analogy is manifested through coherence resonance and stochastic synchronization. In particular, we show both experimentally and numerically that stochastic oscillations that appear due to noise in a system with hard excitation, can be partially synchronized even outside the oscillatory regime of the deterministic system.

Zakharova, Anna; Feoktistov, Alexey; Vadivasova, Tatyana; Schöll, Eckehard

2013-10-01

68

Stochastic resonance induced by bounded noise and periodic signal in an asymmetric bistable system  

NASA Astrophysics Data System (ADS)

Stochastic resonance (SR) induced by the bounded noise in an asymmetric bistable system is investigated. Based on stochastic simulation, the signal power amplification SPA is derived for the case of the additive modulated signal. The simulation results indicate that: (1) the SR phenomenon is weakened by the asymmetry of the system; (2) increasing the frequency ? restricts the SR of the system; (3) there is an optimum value of amplitude A matching the strongest SR phenomenon.

Long, Fei; Guo, Wei; Mei, Dong-Cheng

2012-11-01

69

Acute effects of stochastic resonance whole body vibration  

PubMed Central

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

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

2013-01-01

70

Stochastic Resonance Improves Broadband Encoding in the Cricket Cercal System.  

NASA Astrophysics Data System (ADS)

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

Levin, Jacob

1996-03-01

71

Stochastic Resonance Modulates Neural Synchronization within and between Cortical Sources  

PubMed Central

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.

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

2010-01-01

72

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

PubMed

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

Guo, Daqing; Li, Chunguang

2012-06-09

73

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

74

Suprathreshold stochastic resonance in multilevel threshold system driven by multiplicative and additive noises  

NASA Astrophysics Data System (ADS)

The suprathreshold stochastic resonance in multithreshold neuronal networks system driven by multiplicative Gaussian noise and additive Gaussian noise is studied. The expression of the mutual information is derived, and the effects of the noise intensity and system parameter on mutual information are discussed. It is found that adjusting the additive noise intensity is more effective than adjusting the multiplicative noise intensity to enhance information transmission, and the more the number of devices, the more apparent the phenomenon of suprathreshold stochastic resonance. Moreover, we also found that the selection of threshold is very important in the process of information transmission.

Guo, Yongfeng; Tan, Jianguo

2013-10-01

75

Stochastic resonance in a model of opinion formation on small-world networks  

NASA Astrophysics Data System (ADS)

We analyze the phenomenon of stochastic resonance in an Ising-like system on a small-world network. The system, which is subject to the combined action of noise and an external modulation, can be interpreted as a stylized model of opinion formation by imitation under the effects of a ``fashion wave''. Both the amplitude threshold for the detection of the external modulation and the width of the stochastic-resonance peak show considerable variation as the randomness of the underlying small-world network is changed.

Kuperman, M.; Zanette, D.

2002-04-01

76

Stochastic Resonance in a Bistable System Driven by Weak Periodic Signal with Multiple Delays  

NASA Astrophysics Data System (ADS)

The phenomenon of stochastic resonance in a bistable system with multiple delays is investigated. The analytic expression of approximation stationary probability density is obtained by using small delay approximation based on probability density approach. Numerical simulation is performed and it is shown that the analytic results are in good agreement with Monte Carlo simulation. Then the expression of the signal-to-noise (SNR) is derived by using two-state theory. Finally, the effect of multiple delays on SNR is discussed. It is found that the stochastic resonance phenomenon can be suppressed or promoted when multiple delays are increased.

Zhang, Hui-Qing; Xu, Wei; Sun, Chun-Yan; Xu, Yong

77

MODELING OF COUPLED EDGE STOCHASTIC AND CORE RESONANT MAGNETIC FIELD EFFECTS IN DIVERTED TOKAMAKS  

SciTech Connect

Attaining the highest performance in poloidally diverted tokamaks requires resonant magnetic perturbation coils to avoid core instabilities (locked, resistive wall and neoclassical tearing modes). These coils also perturb the pedestal and edge region, causing varying degrees of stochasticity with remnant islands. The effects of the DIII-D locked mode control coil on the edge and core of Ohmic plasmas are modeled with the field line integration code TRIP3D and compared with experimental measurements. Without detailed profile analysis and field line integration, it is difficult to establish whether a given response is due to a ''core mode'' or an ''edge stochastic boundary.'' In diverted Ohmic plasmas, the boundary stochastic layer displays many characteristics associated with such layers in non-diverted tokamaks. Comparison with stochastic boundary results from non-diverted tokamaks indicates that a significant difference in diverted tokamaks is a ''focusing'' of the magnetic field line loss into the vicinity of the divertor.

EVANS, T.E.; MOYER, R.A.

2002-06-01

78

Coherence Resonance-Induced Stochastic Neural Firing at a Saddle-Node Bifurcation  

NASA Astrophysics Data System (ADS)

Coherence resonance at a saddle-node bifurcation point and the corresponding stochastic firing patterns are simulated in a theoretical neuronal model. The characteristics of noise-induced neural firing pattern, such as exponential decay in histogram of interspike interval (ISI) series, independence and stochasticity within ISI series are identified. Firing pattern similar to the simulated results was discovered in biological experiment on a neural pacemaker. The difference between this firing and integer multiple firing generated at a Hopf bifurcation point is also given. The results not only revealed the stochastic dynamics near a saddle-node bifurcation, but also gave practical approaches to identify the saddle-node bifurcation and to distinguish it from the Hopf bifurcation in neuronal system. In addition, many previously observed firing patterns can be attribute to stochastic firing pattern near such a saddle-node bifurcation.

Gu, Huaguang; Zhang, Huimin; Wei, Chunling; Yang, Minghao; Liu, Zhiqiang; Ren, Wei

79

Internal noise stochastic resonance for intracellular calcium oscillations in a cell system  

NASA Astrophysics Data System (ADS)

By constructing a mesoscopic stochastic model for intracellular calcium oscillations in a cell system, we have investigated how the internal noise would influence the calcium oscillations of such a system using stochastic simulation methods and chemical Langevin method. It is found that stochastic calcium oscillations appear when the internal noise is considered, while the deterministic model only yields steady state. The performance of such oscillations undergoes a maximum with the variation of the internal noise level, indicating the occurrence of internal noise stochastic resonance. Interestingly, we find that the optimal system size matches well with the real cell size when the control parameter is tuned near the left Hopf bifurcation point, and such a match is robust to the variation of the control parameters.

Li, Hongying; Hou, Zhonghuai; Xin, Houwen

2005-06-01

80

Harmonic stochastic resonance-enhanced signal detecting in NW small-world neural network  

NASA Astrophysics Data System (ADS)

The harmonic stochastic resonance-enhanced signal detecting in Newman-Watts small-world neural network is studied using the Hodgkin-Huxley dynamical equation with noise. If the connection probability p, coupling strength gsyn and noise intensity D matches well, higher order resonance will be found and an optimal signal-to-noise ratio will be obtained. Then, the reasons are given to explain the mechanism of this appearance.

Wang, Dao-Guang; Liang, Xiao-Ming; Wang, Jing; Yang, Cheng-Fang; Liu, Kai; Lü, Hua-Ping

2010-11-01

81

Single effective neuron: dendritic coupling effects and stochastic resonance  

Microsoft Academic Search

We consider a model of a neuron coupled with a surrounding dendritic network subject to Langevin noise and a weak periodic modulation. Through an adiabatic elimination procedure, the single-neuron dynamics are extracted from the coupled stochastic differential equations describing the network of dendrodendritic interactions.Our approach yields a“reduced neuron” model whose dynamics may correspond to neurophysiologically realistic behavior for certain ranges

Adi R. Bulsara; A. J. Maren; G. Schmera

1993-01-01

82

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

Microsoft Academic Search

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

Deniz Sezer; Jack H. Freed

2008-01-01

83

Resonant Character of Edge Plasma Parameters in Stochastic Boundary Experiments at DIII-D and TEXTOR  

Microsoft Academic Search

Dependence of electron pressure pe profiles on the edge safety factor during resonant magnetic perturbations (RMPs) is analyzed and compared to heat and particle fluxes. For TEXTOR, a strong reduction of pe and an increase of target fluxes is measured when the inward penetration of the vacuum stochastic layer is maximized. For DIII-D, target heat and particle fluxes follow the

O. Schmitz; B. D. Bray; N. H. Brooks; T. E. Evans; A. W. Leonard; T. H. Osborne; W. P. West; M. E. Fenstermacher; M. Groth; C. J. Lasnier; H. Frerichs; M. Lehnen; B. Unterberg; M. W. Jakubowski; R. A. Moyer; J. G. Watkins

2008-01-01

84

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

Microsoft Academic Search

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,

Minato Kawaguchi; Hiroyuki Mino; Dominique M. Durand

2008-01-01

85

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

Microsoft Academic Search

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

Kurt Wiesenfeld; Frank Moss

1995-01-01

86

Noise enhancement of information transfer in crayfish mechanoreceptors by stochastic resonance  

Microsoft Academic Search

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

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

1993-01-01

87

Central cross-modal stochastic resonance in human tactile blink reflex  

Microsoft Academic Search

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

Hideaki Yasuda; Tsuyoshi Miyaoka; Jun Horiguchi; Yoshiharu Yamamoto

2007-01-01

88

Resonances and noise in a stochastic Hindmarsh-Rose model of thalamic neurons.  

PubMed

Thalamic neurons exhibit subthreshold resonance when stimulated with small sine wave signals of varying frequency and stochastic resonance when noise is added to these signals. We study a stochastic Hindmarsh-Rose model using Monte-Carlo simulations to investigate how noise, in conjunction with subthreshold resonance, leads to a preferred frequency in the firing pattern. The resulting stochastic resonance (SR) exhibits a preferred firing frequency that is approximately exponential in its dependence on the noise amplitude. In similar experiments, frequency dependent SR is found in the reliability of detection of alpha-function inputs under noise, which are more realistic inputs for neurons. A mathematical analysis of the equations reveals that the frequency preference arises from the dynamics of the slow variable. Noise can then transfer the resonance over the firing threshold because of the proximity of the fast subsystem to a Hopf bifurcation point. Our results may have implications for the behavior of thalamic neurons in a network, with noise switching the membrane potential between different resonance modes. PMID:12875337

Reinker, Stefan; Puil, Ernest; Miura, Robert M

2003-07-01

89

Resonances and Particle Stochastization in Nonhomogeneous Electromagnetic Fields  

Microsoft Academic Search

In the present paper we investigate the resonant interaction between monochromatic electromagnetic waves and charged particles in configurations with magnetic field reversals (e.g., in the earth magnetotail). The smallness of certain physical parameters allows us to solve this problem using perturbation theory, reducing the problem of resonant wave–particle interaction to the analysis of slow passages of a particle through a

D. L. Vainchtein; E. V. Rovinsky; L. M. Zelenyi; A. I. Neishtadt

2004-01-01

90

A Review of Parameter-Induced Stochastic Resonance and Current Applications in Two-Dimensional Image Processing  

Microsoft Academic Search

\\u000a Stochastic resonance (SR) is a phenomenon that nonlinear system synchronizes with noise to boost a resonant-like behavior.\\u000a Parameter-induced stochastic resonance (PSR) proposed in this paper is realized by optimally tuning system parameters without\\u000a adding any noise. It has been proved the performance of PSR is better than traditional SR technique which is in fact a particular\\u000a case in PSR region.

Yibing Yang; Bohou Xu

91

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

PubMed Central

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.

2012-01-01

92

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

SciTech Connect

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

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

2008-06-15

93

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

94

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

NASA Astrophysics Data System (ADS)

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.

Perc, M.

2009-05-01

95

Stochastic Transport Modeling of Resonant Magnetic Perturbations in DIII-D  

SciTech Connect

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

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

2006-06-01

96

Functional Stochastic Resonance in the Human Brain: Noise Induced Sensitization of Baroreflex System  

NASA Astrophysics Data System (ADS)

We demonstrate experimentally that noise can enhance the homeostatic function in the human blood pressure regulatory system. The results show that the compensatory heart rate response to the weak periodic signal introduced at the venous blood pressure receptor is optimized by adding noise to the arterial blood pressure receptor. We conclude that this functional stochastic resonance most likely results from the interaction of noise with signal in the brain stem, where the neuronal inputs from these two different receptors first join together.

Hidaka, Ichiro; Nozaki, Daichi; Yamamoto, Yoshiharu

2000-10-01

97

Application of stochastic resonance in target detection in shallow-water reverberation  

NASA Astrophysics Data System (ADS)

In the processing of sea-bottom echo signal, the total received noise is approximated to Lorentzian form according to its vertical coherence. Then a method based on parameter-induced stochastic resonance (PSR) is presented. By means of tuning system parameters, numerical simulation shows that PSR method can effectively recover the spatial signal interfered by Gaussian noise. It also shows that PSR method has well applicability when processing spatial signal interfered by K-distributed envelope noise.

Xu, Bohou; Zeng, Lingzao; Li, Jianlong

2007-06-01

98

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

Microsoft Academic Search

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.

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

2006-01-01

99

Stochastic resonance effects reveal the neural mechanisms of transcranial magnetic stimulation  

PubMed Central

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.

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

2011-01-01

100

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

SciTech Connect

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.}

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

1996-06-01

101

Stochastic resonance in the fractional Langevin equation driven by multiplicative noise and periodically modulated noise  

NASA Astrophysics Data System (ADS)

First we study the time and frequency characteristics of fractional calculus, which reflect the memory and gain properties of fractional-order systems. Then, the fractional Langevin equation driven by multiplicative colored noise and periodically modulated noise is investigated in the over-damped case. Using the moment equation method, the exact analytical expression of the output amplitude is derived. Numerical results indicate that the output amplitude presents stochastic resonance driven by periodically modulated noise. For low frequency signal, the higher the system order is, the bigger the resonance intensity will be; while the result of high frequency signal is quite the contrary. This is consistent with the frequency characteristics of fractional calculus.

Yu, Tao; Zhang, Lu; Luo, Mao-Kang

2013-10-01

102

Friction-induced Resonance of a Stochastic Oscillator  

SciTech Connect

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

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

2009-10-29

103

Phase synchronization and stochastic resonance effects in the crayfish caudal photoreceptor  

NASA Astrophysics Data System (ADS)

We study the nonlinear response of the crayfish caudal photoreceptor to periodic mechanical stimuli in terms of stochastic synchronization. The amplitude and frequency of the mechanical stimuli and the light level are used as control parameters. The system shows multiple locking regions as the stimulus frequency is varied. We find that the synchronization index increases as the signal-to-noise ratio (SNR) of the periodic drive, in response to increasing light levels; this effect exhibits features similar to stochastic resonance. We demonstrate a nonlinear rectification effect in which the SNR of the second harmonic of the input stimulus increases as the light level is raised, and show that the corresponding synchronization index increases as the SNR of the second harmonic.

Bahar, Sonya; Neiman, Alexander; Wilkens, Lon A.; Moss, Frank

2002-05-01

104

Effects of signal spectrum varying on signal processing by parameter-induced stochastic resonance  

NASA Astrophysics Data System (ADS)

The effects of signal spectrum varying on signal processing by the method of parameter-induced stochastic resonance (PSR) are investigated. For a binary signal with a smooth power spectral density (PSD), when the PSD curve becomes sharper and narrower, the performance of the nonlinear system via PSR is better. For a multi-frequency signal formed by sine waves with different frequencies, the larger the signal spectral density is, the lower the ability of the PSR system processing signal is. And the signal-to-noise ratio (SNR) gain of the PSR system is increased with the increasing height of the spectral line. Moreover, with the method of PSR, the stochastic signal (the combination of sine waves and noise) improvement is obvious. The results obtained via this method are superior to those with a linear filter.

Li, Jianlong; Xu, Bohou

2006-02-01

105

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

SciTech Connect

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

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

1994-12-01

106

A Review of Parameter-Induced Stochastic Resonance and Current Applications in Two-Dimensional Image Processing  

NASA Astrophysics Data System (ADS)

Stochastic resonance (SR) is a phenomenon that nonlinear system synchronizes with noise to boost a resonant-like behavior. Parameter-induced stochastic resonance (PSR) proposed in this paper is realized by optimally tuning system parameters without adding any noise. It has been proved the performance of PSR is better than traditional SR technique which is in fact a particular case in PSR region. The applications of PSR to signal processing and target detection in shallow water reverberation have been reviewed. A new concept of two-dimensional parameter-induced stochastic resonance (2D-PSR) and its applications in the restoration of degraded image and pattern recognition of remote sensing image are developed.

Yang, Yibing; Xu, Bohou

107

Medication (for Vestibular Disorders)  

MedlinePLUS

... Exercise Medication Surgical Procedures Types of Vestibular Disorders Medication Can Medication Help Me Feel Better? The use of medication in treating vestibular disorders depends on whether the ...

108

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

PubMed Central

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.

Lugo, Eduardo; Doti, Rafael; Faubert, Jocelyn

2008-01-01

109

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

NASA Astrophysics Data System (ADS)

The idea of Logical Stochastic Resonance is adapted and applied to an autoregulatory gene network in the bacteriophage ?. 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 gate can be changed after the network has been assembled: this allows a single gene network to be used for many different applications in the emerging field of synthetic biology.

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

2011-01-01

110

Stochastic Resonance in a Spatially Symmetric and Flashing Periodic Potential Subjected to Correlated Noises  

NASA Astrophysics Data System (ADS)

A Brownian particle in a spatially symmetric and Bashing periodic potential subjected to correlated noises is investigated. The exact expression of its current is analytically derived. The numerical results indicate that its current as a function of noise intensity exhibits two peaks in the case of positive correlations, and two vales in the case of negative correlations, i.e., a novel stochastic resonance (SR) phenomenon. The SR is attributed to the harmonic cooperation between the noises and the Bashing periodic potential. The conditions under which the SR occurs are also presented.

Nie, Lin-Ru; Gong, Yu-Lan; Mei, Dong-Cheng

2009-10-01

111

Novel class of neural stochastic resonance and error-free information transfer.  

PubMed

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. PMID:18517832

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

2008-03-19

112

Central cross-modal stochastic resonance in human tactile blink reflex  

NASA Astrophysics Data System (ADS)

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

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

2007-07-01

113

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

NASA Astrophysics Data System (ADS)

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.

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

2008-03-01

114

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

PubMed

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

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

2012-04-11

115

Resonant Pedestal Pressure Reduction Induced by a Thermal Transport Enhancement due to Stochastic Magnetic Boundary Layers in High Temperature Plasmas  

SciTech Connect

Good alignment of the magnetic field line pitch angle with the mode structure of an external resonant magnetic perturbation (RMP) field is shown to induce modulation of the pedestal electron pressure p{sub e} in high confinement high rotation plasmas at the DIII-D tokamak with a shape similar to ITER, the next step tokamak experiment. This is caused by an edge safety factor q{sub 95} resonant enhancement of the thermal transport, while in contrast, the RMP induced particle pump out does not show a significant resonance. The measured p{sub e} reduction correlates to an increase in the modeled stochastic layer width during pitch angle variations matching results from resistive low rotation plasmas at the TEXTOR tokamak. These findings suggest a field line pitch angle resonant formation of a stochastic magnetic edge layer as an explanation for the q{sub 95} resonant character of type-I edge localized mode suppression by RMPs.

Schmitz, O.; Frerichs, H.; Lehnen, M.; Reiter, D.; Samm, U.; Unterberg, B. [Forschungszentrum Juelich GmbH, IEF4-Plasma Physics, 52428 Juelich (Germany); Evans, T. E.; Austin, M. E.; Bray, B. D.; Brooks, N. H.; Leonard, A. W.; Osborne, T. H.; Schaffer, M. J.; West, W. P. [General Atomics, San Diego, California 92186-5608 (United States); Fenstermacher, M. E.; Groth, M.; Lasnier, C. J. [Lawrence Livermore National Laboratory, Livermore, California (United States); Unterberg, E. A. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee (United States); Jakubowski, M. W. [Max Planck Institut fuer Plasmaphysik, Greifswald (Germany); Mordijck, S. [University of California, San Diego, La Jolla, California 92093 (United States)

2009-10-16

116

Stochastic resonance on Newman-Watts networks of Hodgkin-Huxley neurons with local periodic driving  

NASA Astrophysics Data System (ADS)

We study the phenomenon of stochastic resonance on Newman-Watts small-world networks consisting of biophysically realistic Hodgkin-Huxley neurons with a tunable intensity of intrinsic noise via voltage-gated ion channels embedded in neuronal membranes. Importantly thereby, the subthreshold periodic driving is introduced to a single neuron of the network, thus acting as a pacemaker trying to impose its rhythm on the whole ensemble. We show that there exists an optimal intensity of intrinsic ion channel noise by which the outreach of the pacemaker extends optimally across the whole network. This stochastic resonance phenomenon can be further amplified via fine-tuning of the small-world network structure, and depends significantly also on the coupling strength among neurons and the driving frequency of the pacemaker. In particular, we demonstrate that the noise-induced transmission of weak localized rhythmic activity peaks when the pacemaker frequency matches the intrinsic frequency of subthreshold oscillations. The implications of our findings for weak signal detection and information propagation across neural networks are discussed.

Ozer, Mahmut; Perc, Matjaž; Uzuntarla, Muhammet

2009-03-01

117

Experimental investigation of noise-assisted information transmission and storage via stochastic resonance  

NASA Astrophysics Data System (ADS)

We present experimental results on the information transmission and storage via stochastic resonance in circuits designed and built around Schmitt triggers (STs). First, we investigate the performance of a transmission line comprised of five STs and show it to exhibit stochastic resonance. Each ST in the line is fed with white Gaussian noise, and the first ST is driven by a non-return-to-zero pseudo-random bit sequence with sub-threshold amplitude. Parameters such as bit error rate (Q-factor) are measured (calculated) and shown to exhibit a minimum (maximum) for an optimum amount of noise. Interestingly, we find that system performance degrades with the number of STs as if the system were linear and impaired only by additive Gaussian noise. We then propose and build a 1-bit storage device based on two STs in a loop configuration. We demonstrate that such a system is capable of storing one bit of information only in the presence of noise, and that there is a regime where the efficiency of such a device increases with increasing noise. Our results point to the feasibility of building ‘blocks’ that can transmit, store and eventually process information, whose performance is not only robust against noise, but can actually benefit from it.

Patterson, G. A.; Goya, A. F.; Fierens, P. I.; Ibáñez, S. A.; Grosz, D. F.

2010-05-01

118

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

NASA Astrophysics Data System (ADS)

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.

Lin, Xiu; Gong, Yubing; Wang, Li

2011-12-01

119

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

PubMed

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

Lin, Xiu; Gong, Yubing; Wang, Li

2011-12-01

120

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

PubMed Central

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

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

2013-01-01

121

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

NASA Astrophysics Data System (ADS)

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

Epstein, S.; Paul, M. R.

2013-10-01

122

SPACES: A PC implementation of the stochastic theory of energy loss for narrow-resonance depth profiling  

Microsoft Academic Search

The stochastic theory of charged-particle energy loss in matter has provided an accurate computational method for straggling calculations and for the simulation of excitation curves obtained in narrow-resonance depth profiling. We have developed Fortran programs that perform the autoconvolutions of the primary energy loss function, and the weighted summing of these autoconvolutions needed by the theory for both straggling and

Ion Vickridge; Georges Amsel

1990-01-01

123

Multi-stable stochastic resonance and its application research on mechanical fault diagnosis  

NASA Astrophysics Data System (ADS)

It is difficult to extract the fault features of a rotating machine via vibration analysis due to interference from background noise. Stochastic resonance (SR), used as a method of utilising noise to amplify weak signals in nonlinear dynamical systems, can detect weak signals overwhelmed in the noise. However, the detection effect of current SR methods is still unsatisfactory. To further increase the output signal-to-noise ratio (SNR) and improve the detection effect of SR, the present study proposes an improved SR method with a multi-stable model for identifying the defect-induced rotating machine faults by analysing the influence relationship between the resonance model and the resonance effect. Due to the structural characteristics of three potential wells and two barriers, the proposed resonance model can not only further amplify weak signals, but also convert into a monostable model, a bistable model or a tristable model. This result is achieved by adjusting system parameters and thus obtaining a better matching of the input signals and resonance models. Therefore, the multi-stable SR method, combined with the characteristics of the multi-stable model, can both increase the output SNR and improve the detection effect and also detect the low SNR signals and enhance the processing capability of SR for weak signals. Finally, the proposed method is applied to a gearbox fault diagnosis in a rolling mill in which two local faults located in the big gear and the pinion, respectively, are found successfully. It can be concluded that multi-stable SR method has practical value in engineering.

Li, Jimeng; Chen, Xuefeng; He, Zhengjia

2013-10-01

124

Noise-Induced Sensitization of Human Brain: Toward the Neurological Application of Stochastic Resonance  

NASA Astrophysics Data System (ADS)

In the past decade, it has been recognized that noise can enhance the response of nonlinear systems to weak signals, via a mechanism known as stochastic resonance (SR). Particularly, the concept of SR has generated considerable interest in sensory biology, because it has been shown in several experimental studies that noise can assist neural systems in detecting weak signals which could not be detected in its absence. Recently, we have shown a similar type of noise-induced sensitization of human brain; externally added noise to the brain stem baroreflex centers sensitized their responses in maintaining adequate blood perfusion to the brain itself. Furthermore, the addition of noise has also shown to be useful in compensating for dysfunctions of the baroreflex centers in certain neurological diseases. It is concluded that the statistical physics concept of SR could be useful in sensitizing human brain in health and disease.

Yamamoto, Yoshiharu; Soma, Rika; Hidaka, Ichiro; Nozaki, Daichi; Iso-O, Noriko; Kwak, Shin

2003-05-01

125

Noise-assisted information transfer in crayfish mechanoreceptors: stochastic resonance in a neuronal receptor  

NASA Astrophysics Data System (ADS)

Adding random noise to a weak periodic signal can enhance the flow of information through certain nonlinear physical systems, via a process known as stochastic resonance (SR). We have used crayfish mechanoreceptor cells to investigate the possibility that SR can be induced in neurophysiological systems. Various signal-to-noise ratio (SNR) measurements were derived from the action potentials (spikes) of single receptor cells stimulated with weak periodic signals. Spike noise was controlled by one of two methods: (1) adding external noise to the stimulus, or (2) altering internal noise sources by changing the temperature of the cell. In external noise experiments, an optimal noise level can be identified at which the SNR is maximized. In internal noise experiments, although the SNR increases with increasing noise, no SNR maximum has been observed. These results demonstrate that SR can be induced in single neurons, and suggest that neuronal systems may also be capable of exploiting SR.

Douglass, John K.; Wilkens, Lon A.; Moss, Frank

1993-11-01

126

Stochastic Resonance for a Metapopulation System Subjected to Correlated Colored Noises  

NASA Astrophysics Data System (ADS)

In the present paper, for a Levins metapopulation system that is driven by correlated colored noises, the phenomenon of stochastic resonance (SR) is investigated. Based on the two-state theory and by the use of fast descent method, the expression of the signal-to-noise ratio (SNR) is obtained. Via a numerical simulation, it is shown that the conventional SR occurs in the Levins model for the different values of system parameters. And furthermore, it is revealed that, under the different conditions that if the correlation intensities between the two noises are different, i.e. positive or negative, then all the effects of the addictive noise intensity, the multiplicative noise intensity, the correlated noise intensity and the correlation time on SNR are different.

Wang, Kang-Kang; Liu, Xian-Bin; Li, Sheng-Hong

2013-07-01

127

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

128

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

PubMed Central

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

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

2008-01-01

129

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

NASA Astrophysics Data System (ADS)

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

Gao, Shi-Long

2012-12-01

130

On the generation of ion beamlets in the magnetotail: Resonant acceleration versus stochastic acceleration  

NASA Astrophysics Data System (ADS)

In the Earth plasma sheet boundary layer, two types of ion beams (so-called beamlets of type I and of type II) were investigated for more then two decades. Type I beamlets have energies <20 keV and small velocity dispersion, while type II beamlets have energies up to 100 keV and large velocity dispersion. It is believed that beamlets of type I result from nonadiabatic and resonant acceleration by the cross-tail electric field Ey at the fulfillment of the resonant condition in the current sheet, while beamlets type II could be generated by sufficiently large level of electromagnetic fluctuations in the magnetotail. The resonant condition is very sensitive to the presence of the perturbation and eventually should be destroyed by growing "noise." We performed test particle simulation taking into account two possible acceleration mechanisms, cross-tail electric field Ey and stochastic acceleration due to electromagnetic perturbations. Electromagnetic perturbation were generated by a set of oscillating clouds in the plasma sheet. We obtained that type I beamlets could be observed even in the presence of moderate levels of perturbation ?B˜Bz(z=0), where Bz is a magnetic field component perpendicular to the current sheet plane. Increasing the perturbation level, beamlets of higher energy are obtained. The interplay of ion resonant acceleration and magnetic perturbation in the magnetotail leads to a continuous transition from beamlets of type I to beamlets of type II. A comparison of the numerical results with the observation of ion populations in magnetotail is also discussed.

Dolgonosov, M. S.; Zimbardo, G.; Perri, S.; Greco, A.

2013-09-01

131

Excitation of stochastic oscillations in a resonant millimeter-wave O-type backward-wave tube  

NASA Astrophysics Data System (ADS)

Experimental results are presented on the excitation of stochastic oscillations in a resonant millimeter-wave O-type BWT through the synchronization of its self-oscillations by a narrow-band 3-cm-wave stochastic signal. An analysis is made of the spectra of synchronized oscillations of the tube for a fixed modulating-signal level and for different values of the modulating power; and the dependence of the relative bandwidth of input oscillations and the power of the millimeter-wave oscillations on the power of the modulating signal for different beam currents.

Efimov, B. P.; Krivitskii, B. Ia.; Lukin, K. A.; Mil'Cho, M. V.; Rakitianskii, V. A.

132

Noise-induced Hypersensitivity and Stochastic Resonance: Can Living Systems Use Them at a Molecular Level?  

NASA Astrophysics Data System (ADS)

Living organisms are known to receive and transduce useful signals in a very noisy environment. A natural question whether they can use this noise constructively is still lacking solid answer. Some recent works demonstrated that one of the phenomena where noise plays a constructive role, the stochastic resonance (SR), occurs in biology at system and cellular levels of organization. Its existence at molecular level, in ionic channels of cell membranes, is now a subject for intensive, though mainly theoretical, studies. In the present work we study a simple two-state model of ionic channel together with its continuous equivalent, the asymmetrical Kramers oscillator, with external periodic signal and dichotomous external noise. We found that the new kind of SR appears for adiabatically slow external noise, when its amplitude becomes equal to static bias, thus dynamically recovering the system symmetry. These findings are confirmed with analog circuit simulations. The next promising effect is the noise-induced hypersensitivity to small signals. The phenomenon arises in stochastic systems with on-off intermittency. Such a system at optimal external noise intensity and correlation time becomes sensitive to an ultrasmall signal, amplifying it by many orders of magnitude. Such a hypersensitivity is often robust to additive thermal noise. We speculate that a similar effect might occur in various sensory systems that are known to be very noisy and to display unique sensitivity to environmental signals. A simple model system of two neurons with common strong noise source is hypersensitive to small differential signal only in the ideal case of absence of internal noise.

Gerashchenko, O. V.; Ginzburg, S. L.; Pustovoit, M. A.

2003-05-01

133

Vestibular Evoked Myogenic Potentials in Patients With Acoustic Neuromas  

Microsoft Academic Search

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

Toshihisa Murofushi; Masaki Matsuzaki; Masahiro Mizuno

1998-01-01

134

Stochastic resonance in the logistic growth model with time-modulated correlated noise  

NASA Astrophysics Data System (ADS)

Stochastic resonance in the logistic model driven by time-modulated correlated multiplicative and additive noises is investigated. For small amounts of the two noises, a small amplitude of the additive modulated signal and a small intensity of the time-modulated correlated noise, under the adiabatic approximation, the analysis expressions of the signal-to-noise ratios for different frequencies and equal frequencies of the two modulation forces have been obtained. Theoretical and numerical study shows that the signal-to-noise ratios vary non-monotonically with increasing intensities of the multiplicative and additive noises. The curves of the signal-to-noise ratio versus additive noise strength present two peaks while one peak exists in each of the curves for the signal-to-noise ratio as a function of the multiplicative noise intensity. In addition, for equal frequency of the two modulation forces, the signal-to-noise ratio behaves non-monotonically with increasing amplitude of the time-modulation force.

Huang, Zhi-Qi; Peng, Ya-Na; Guo, Feng

2012-12-01

135

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

SciTech Connect

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

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

2010-10-15

136

Behavioral stochastic resonance associated with large-scale synchronization of human brain activity  

NASA Astrophysics Data System (ADS)

We demonstrate experimentally that enhanced detection of weak visual signals by addition of visual noise is accompanied by an increase in phase synchronization of EEG signals across widely-separated areas of the human brain. In our sensorimotor integration task, observers responded to a weak rectangular gray-level signal presented to their right eyes by pressing and releasing a button whenever they detected an increment followed by a decrement in brightness. Signal detection performance was optimized by presenting randomly-changing-gray-level noise separately to observers' left eyes using a mirror stereoscope. We measured brain electrical activity at the scalp by electroencephalograph (EEG), calculated the instantaneous phase for each EEG signal, and evaluated the degree of large-scale phase synchronization between pairs of EEG signals. Dynamic synchronization-desynchronization patterns were observed and we found evidence of noise-enhanced large-scale synchronization associated with detection of the brightness changes under conditions of noise-enhanced performance. Our results suggest that behavioral stochastic resonance might arise from noise-enhanced synchronization of neural activities across widespread brain regions.

Kitajo, Keiichi; Yamanaka, Kentaro; Nozaki, Daichi; Ward, Lawrence M.; Yamamoto, Yoshiharu

2004-05-01

137

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

138

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

PubMed Central

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

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

2013-01-01

139

Stochastic resonance as a model for financial market crashes and bubbles  

NASA Astrophysics Data System (ADS)

A bistable model of a financial market is considered, aimed at modelling financial crashes and bubbles, based on the Ising model with thermal-bath dynamics and long-range interactions, subject to a weak external information-carrying signal and noise. In the ordered phase, opposite stable orientations of magnetization correspond to the growing and declining market before and after the crash or bubble, and jumps of magnetization direction correspond to crashes and bubbles. It is shown that the influence of an information-carrying signal, assumed to be too weak to induce magnetization jumps, can be enhanced by the external noise via the effect of stochastic resonance. It is argued that in real stock markets the arrival of a piece of information, considered a posteriori to be the cause for a crash or bubble, can be enhanced in a similar way, thus leading to price return whose value is unexpectedly large in comparison with relatively weak importance of this piece of information.

Krawiecki, A.; Holyst, J. A.

2003-01-01

140

Stochastic Resonance Activity Influences Serum Tryptophan Metabolism in Healthy Human Subjects  

PubMed Central

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

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

2011-01-01

141

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

142

Engineering signal processing based on adaptive step-changed stochastic resonance  

NASA Astrophysics Data System (ADS)

Weak signal detection which is under the condition of adiabatic elimination in large parameters can be solved by step-changed stochastic resonance (SCSR) presented by our group. Adaptive SCSR based on approximate entropy (ApEn) is also proposed in this paper, and it can get the best result of SCSR adaptively. Our analysis shows that the ApEn value of periodic signal is related to its frequency and signal-to-noise ratio (SNR), but not to the change of its amplitude and phase. So a periodic signal with definite SNR whose frequency is to be detected can be made under the same sampling condition as the raw data, and its ApEn is calculated as a standard reference. By adjusting the structural parameters and calculation step automatically, a series output of the bistable system can be got, and an ApEn distance matrix can be constructed. After getting the minimum value of the matrix, the best parameters of the non-linear system and calculation step can be obtained. Two examples of detecting weak signal mixed with heavy noise are presented in the end to illustrate that SCSR and its adaptive solution are effective for signal processing.

Qiang, Li; Taiyong, Wang; Yonggang, Leng; Wei, Wang; Guofeng, Wang

2007-07-01

143

Vestibular evoked myogenic potential in vestibular neuritis  

Microsoft Academic Search

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

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

144

Slope-based stochastic resonance: how noise enables phasic neurons to encode slow signals.  

PubMed

Fundamental properties of phasic firing neurons are usually characterized in a noise-free condition. In the absence of noise, phasic neurons exhibit Class 3 excitability, which is a lack of repetitive firing to steady current injections. For time-varying inputs, phasic neurons are band-pass filters or slope detectors, because they do not respond to inputs containing exclusively low frequencies or shallow slopes. However, we show that in noisy conditions, response properties of phasic neuron models are distinctly altered. Noise enables a phasic model to encode low-frequency inputs that are outside of the response range of the associated deterministic model. Interestingly, this seemingly stochastic-resonance (SR) like effect differs significantly from the classical SR behavior of spiking systems in both the signal-to-noise ratio and the temporal response pattern. Instead of being most sensitive to the peak of a subthreshold signal, as is typical in a classical SR system, phasic models are most sensitive to the signal's rising and falling phases where the slopes are steep. This finding is consistent with the fact that there is not an absolute input threshold in terms of amplitude; rather, a response threshold is more properly defined as a stimulus slope/frequency. We call the encoding of low-frequency signals with noise by phasic models a slope-based SR, because noise can lower or diminish the slope threshold for ramp stimuli. We demonstrate here similar behaviors in three mechanistic models with Class 3 excitability in the presence of slow-varying noise and we suggest that the slope-based SR is a fundamental behavior associated with general phasic properties rather than with a particular biological mechanism. PMID:20585612

Gai, Yan; Doiron, Brent; Rinzel, John

2010-06-24

145

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

NASA Astrophysics Data System (ADS)

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

Morse, Robert P.; Roper, Peter

2000-05-01

146

Slope-Based Stochastic Resonance: How Noise Enables Phasic Neurons to Encode Slow Signals  

PubMed Central

Fundamental properties of phasic firing neurons are usually characterized in a noise-free condition. In the absence of noise, phasic neurons exhibit Class 3 excitability, which is a lack of repetitive firing to steady current injections. For time-varying inputs, phasic neurons are band-pass filters or slope detectors, because they do not respond to inputs containing exclusively low frequencies or shallow slopes. However, we show that in noisy conditions, response properties of phasic neuron models are distinctly altered. Noise enables a phasic model to encode low-frequency inputs that are outside of the response range of the associated deterministic model. Interestingly, this seemingly stochastic-resonance (SR) like effect differs significantly from the classical SR behavior of spiking systems in both the signal-to-noise ratio and the temporal response pattern. Instead of being most sensitive to the peak of a subthreshold signal, as is typical in a classical SR system, phasic models are most sensitive to the signal's rising and falling phases where the slopes are steep. This finding is consistent with the fact that there is not an absolute input threshold in terms of amplitude; rather, a response threshold is more properly defined as a stimulus slope/frequency. We call the encoding of low-frequency signals with noise by phasic models a slope-based SR, because noise can lower or diminish the slope threshold for ramp stimuli. We demonstrate here similar behaviors in three mechanistic models with Class 3 excitability in the presence of slow-varying noise and we suggest that the slope-based SR is a fundamental behavior associated with general phasic properties rather than with a particular biological mechanism.

Gai, Yan; Doiron, Brent; Rinzel, John

2010-01-01

147

Vestibular Perception following Acute Unilateral Vestibular Lesions  

PubMed Central

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

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

2013-01-01

148

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

NASA Astrophysics Data System (ADS)

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.

Kim, Won Kyu; Sung, Wokyung

2012-08-01

149

Vestibular presentation in platybasia  

Microsoft Academic Search

The platybasia consists of an upward bulge or invagination of the occiput near the foramen magnum. These patients mostly presents\\u000a with neurological symptoms. The present case is a rare variant presenting with vestibular disorders only.

S. C. Mishra

1994-01-01

150

Vestibular Schwannoma (Acoustic Neuroma)  

Microsoft Academic Search

Vestibular schwannomas (VS) or acoustic neuromas are benign tumors arising from Schwann cells of the vestibular branch of\\u000a the eighth cranial nerve. The tumor was first described 1910 by Henschen, who provided evidence that it originates from the\\u000a Schwann cells. Nevertheless, the term acoustic neuroma was commonly used. The National Institute of Health decided in 1992\\u000a in a Consensus Development

Anca-Ligia Grosu; Elmar Oestreicher; Claudius Fauser; Christianto Lumenta; Wolfgang J. Arnold; Michael Molls

151

Stationary Properties and Stochastic Resonance for a Saturation Laser Model with Cross-correlation Between Quantum Noise Terms  

NASA Astrophysics Data System (ADS)

The stationary properties of a saturation laser model with cross-correlation between the real and imaginary parts of the quantum noise are investigated theoretically. Using the Novikov theorem and the Sargent technique, we obtain the analytic expressions of the stationary probability density distribution, the mean, the variance and the skewness of the saturation laser model. The cross-correlation coefficient ? and other parameters can make the stationary probability density distribution P st ( I) generate interesting two-extrema structure, one-extremum structure, or no-extremum structure. It is clearly found that a first- order-like-transition is induced by the coupling strength | ?| of the complex quantum noise terms in the saturation laser model. When the laser system is operated above the threshold, the mean < I> becomes larger and the output of the laser intensity increases; however the coupling strength | ?| attenuates the output of the laser intensity. When the laser is operated near and below the threshold, the mean < I> becomes smaller, the output of the laser intensity decreases, and | ?| still attenuates the output of the laser intensity. When a periodic signal is added to a saturation laser model with cross-correlation between quantum noise terms, the interesting stochastic resonance phenomena occur at ?=0. The noise intensity Q decreases the values of the resonance peak, however, the amplitude of the periodic signal B enhances the values of the resonance peak.

Zhu, Ping; Fu, Yang

2009-07-01

152

Measures of periodicity for time series analysis of threshold-crossing events. Ghost stochastic resonance in glacial climate?  

NASA Astrophysics Data System (ADS)

Large-amplitude climate shifts, the so-called Dansgaard-Oeschger events, repeatedly occurred throughout the last ice age. These events, which are apparently threshold-crossing events, show a reported tendency to recur preferably in near multiples of about 1470 years. Several non-linear resonance mechanisms were proposed to explain this recurrence pattern in response to noise and/or periodic forcing. Standard methods of linear time series analysis are not sufficient to distinguish between these hypotheses, owing to the threshold-crossing dynamics of the events. Recently, new approaches were made by means of null-hypothesis testing with Monte Carlo methods. A major hurdle in this approach is the need of efficient, but yet simple measures of regularity that allow to distinguish between the proposed resonance mechanisms. By means of surrogate time series (i.e. by using a large ensemble of Dansgaard-Oeschger events as simulated with a very simple two-state model) I here test the ability of three standard measures of periodicity to distinguish between a scenario of solely noise-induced events and a ghost stochastic resonance scenario. Only one measure is found to be applicable for that purpose. The choice of adequate measures, which is not trivial, should be given more attention in future studies that focus on the question what triggered threshold-crossing events such as Dansgaard-Oeschger events.

Braun, H.

2009-07-01

153

Hereditary familial vestibular degenerative diseases.  

PubMed

Identification of genes involved in hereditary vestibular disease is growing at a remarkable pace. Mutant mouse technology can be an important tool for understanding the biological mechanism of human vestibular diseases. PMID:11710498

Sun, J C; Van Alphen, A M; Wagenaar, M; Huygen, P; Hoogenraad, C C; Hasson, T; Koekkoek, S K; Bohne, B A; De Zeeuw, C I

2001-10-01

154

Vestibular rehabilitation after mild traumatic brain injury with vestibular pathology.  

PubMed

Vestibular complaints are the most frequent sequelae of mTBI. Vestibular physical therapy has been established as the most important treatment modality for this group of patients. Nevertheless there is little work objectively documenting the impact of vestibular physical therapy on this group of patients. Studies have been completed in the past examining clinical measures like the GCS on overall recovery pattern after TBI. But outcomes measures specifically aimed at examining the adequacy of vestibular tests to track vestibular recoveryhave remained lacking. Scherer and Schubert reinforced the need for best practice vestibular assessment for formulation of appropriate vestibular physical therapy treatment strategies. Now the application of vestibular testing and rehabilitation in this patient population is needed to provide information on objective outcome measures. Vestibular physical therapy is most effective when applied in a customized fashion. While we and others have developed vestibular physical therapy procedures that are applied in best practices for mTBI vestibular patients, these therapies must be customized for the patient entry level of function and expectation level of recovery. Knowledge of the patient's disability and diagnosis is critical to build the foundation for return to activity, work, or sport. PMID:22027078

Gottshall, Kim

2011-01-01

155

[Vestibular findings in divers].  

PubMed

The author investigated 21 professional divers who had worked in overpressure conditions for many years. Main abnormalities were found in the vestibular system, especially in the caloric and optokinetic tests; the changes appeared in 61.9% of the sample. Asymmetry and dysrhythmia of evoked nystagmic responses were ascertained in these cases. The results of the auditory and tympanometry tests were normal in most examined persons. The acoustic reflex threshold increased in 38.1%. The lower ventilatory function of the eustachian tube was found only in one case but the audiometrical test was normal. From the ethiopathogenetic point of view the frequent and intense changes of pressure, temperature and posture may cause vegetative dysregulation with the following vascular deviations in the peripheral and central vestibular apparatus and in the brain stem. The adaptive mechanisms also modify the nystagmic reactions: thus they participate in the vestibular abnormalities. PMID:7973421

Novotný, Z

1993-01-01

156

Vestibular-Ocular Reflex  

NSDL National Science Digital Library

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

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

2013-01-30

157

The increase of gravitational-wave interferometer sensitivity by employing stochastic resonance mechanism in nonlinear white-light cavity  

NASA Astrophysics Data System (ADS)

We consider a nonlinear white-light cavity (WLC), operating in gravitational-wave (GW) interferometer arm. By using coupled-wave equations for nonlinear waves, we analyze nonlinear resonance and obtain a simple asymptotic equation for calculating of WLC output phase shift, when the operation point is placed very close to instability point. In a standard nonlinear cavity it would require the instability of laser frequency less than 10-21 however in the nonlinear WLC the requirement to frequency instability is much more tolerant - about 10-14. We calculated the shift of output phase and output signal-to-displacement noise ratio (SDNRout) in bistable regime assuming that cavity length changes under the action of a quasi-sinusoidal GW and a displacement noise. Due to the stochastic resonance (SR) phenomenon presented here, the SDNRout decreases non-monotonically when displacement noise increases: at an optimum level of displacement noise the SDNRout sharply increases before further decrease. Therefore due to the SR mechanism the output signal becomes less noisy. For example: if the conventional value of SDNRout is 0.05 at detection bandwidth 100 Hz, then the performance of SR increases this value ~7 times, and SDNRout becomes ~0.35. Thus we propose for the first time an approach, which is capable to increase the SDNRout of GW interferometer at given amplitude of displacement noise.

Karapetyan, G. G.

2004-08-01

158

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

PubMed Central

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.

Beier, Christian; Steinhoff, Heinz-Jurgen

2006-01-01

159

Vestibular postural control model  

Microsoft Academic Search

Current models for physiological components and a posture control experiment conducted with three normal subjects form the basis for a model which seeks to describe quantitatively the control of body sway when only vestibular motion cues are used. Emphasis is placed on delineating the relative functional roles of the linear and the angular acceleration sensors and on modeling the functional

Lewis M. Nashner

1972-01-01

160

Magnetic resonance image analysis by information theoretic criteria and stochastic site models  

Microsoft Academic Search

Abstract, Quantitative analysis of magnetic resonance (MR) images is a powerful tool for image-guided diagnosis, monitoring, and intervention. The major tasks involve tissue quantification and image segmentation where both the pixel and context images are considered. To extract clinically useful information from images that might be lacking in prior knowledge, we introduce an unsu-pervised tissue characterization algorithm that is both

Yue Wang; Tülay Adali; Jianhua Xuan; Zsolt Szabo

2001-01-01

161

Constructing the davies process of resonance fluorescence with quantum stochastic calculus  

NASA Astrophysics Data System (ADS)

The starting point is a given semigroup of completely positive maps on the 2×2 matrices. This semigroup describes the irreversible evolution of a decaying two-level atom. By using the integral-sum kernel approach to quantum stochastic calculus, the two-level atom is coupled to an environment, which in this case will be interpreted as the electromagnetic field. The irreversible time evolution of the two-level atom then stems from the reversible time evolution of the atom and the field together. Mathematically speaking, a Markov dilation of the semigroup has been constructed. The next step is to drive the atom by a laser and to count the photons emitted into the field by the decaying two-level atom. For every possible sequence of photon counts, a map is constructed that gives the time evolution of the two-level atom implied by that sequence. The family of maps obtained in this way forms a so-called Davies process. In his book, Davies describes the structure of these processes, which brings us into the field of quantum trajectories. Within the model presented in this paper, the jump operators are calculated and the resulting counting process is briefly described.

Bouten, L.; Maassen, H.; Kümmerer, B.

2003-06-01

162

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

PubMed

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

Majer, Niels; Schöll, Eckehard

2009-01-12

163

Stochastic Resonance in a Single-Mode Laser Driven by Quadratic Colored Pump Noise and Quantum Noise with Cross-Correlation Between Real and Imaginary Parts of Noise  

NASA Astrophysics Data System (ADS)

Based on the single-mode laser noise model driven by quadratic colored pump noise and quantum noise with cross-correlation between real and imaginary parts of noise proposed in International Journal of Modern Physics B 20, 5383 (2006) and Phys. Rev. E 73, 023802 (2006), the stochastic resonance (SR) of laser intensity is investigated by virtue of the linearized approximation. The analytic expression of signal-to-noise ratio (SNR) is calculated. It is found that the phenomena of stochastic resonance respectively exist in the curves of the SNR versus the noise cross-correlation coefficient ?p and the SNR versus the pump parameter a, as well as the SNR versus the signal frequency bar {? } for the model. It is shown that there are three different types of SR in the model: the conventional form of SR, the SR in the broad sense and the bona fide SR.

Xu, De-Sheng; Cao, Li; Wu, Da-Jin

164

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

NASA Astrophysics Data System (ADS)

Data from the LIGO Livingston interferometer and the ALLEGRO resonant-bar detector, taken during LIGO’s fourth science run, were examined for cross correlations indicative of a stochastic gravitational-wave background in the frequency range 850 950 Hz, with most of the sensitivity arising between 905 and 925 Hz. ALLEGRO was operated in three different orientations during the experiment to modulate the relative sign of gravitational-wave and environmental correlations. No statistically significant correlations were seen in any of the orientations, and the results were used to set a Bayesian 90% confidence level upper limit of ?gw(f)?1.02, which corresponds to a gravitational-wave strain at 915 Hz of 1.5×10-23Hz-1/2. In the traditional units of h1002?gw(f), this is a limit of 0.53, 2 orders of magnitude better than the previous direct limit at these frequencies. The method was also validated with successful extraction of simulated signals injected in hardware and software.

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

2007-07-01

165

Vestibular contributions to bodily awareness.  

PubMed

The vestibular system has widespread interactions with multisensory cortical networks, including the somatosensory areas. Several clinical observations suggested that vestibular signals are essential to compute more abstract cognitive representations of the body. However, the existing literature is generally based on isolated reports. We aimed to provide both a theoretical framework, and an experimental method to investigate potential vestibular contributions to somatic cognition. Accordingly, we have investigated effects of galvanic vestibular stimulation (GVS) on the localisation of a stimulus on the skin of the hand (a process that we define as somatoperception) and on the implicit representation of the hand size and shape (involving a different process which we define as somatorepresentation). Vestibular input influenced the localisation of tactile stimuli on the hand: touches on the dorsum of the hand were perceived as shifted toward the wrist. The specific polarity of vestibular stimulation influences the localisation errors. Right anodal and left cathodal, which influences both cerebral hemispheres, induced a stronger localisation bias compared to left anodal and right cathodal GVS, which influences primarily the right hemisphere. Although our data confirmed previous findings that the body model of the shape of the hand is massively distorted, vestibular inputs do not contribute to these distortions. Our results suggest that vestibular input influences the registration of somatosensory input onto a map of the body (somatoperception), but does not influence stored knowledge about the spatial organisation of the body as a physical object (somatorepresentation). PMID:23624312

Ferrè, Elisa Raffaella; Vagnoni, Eleonora; Haggard, Patrick

2013-04-25

166

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

PubMed Central

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.

Li, Chunhe; Wang, Erkang; Wang, Jin

2011-01-01

167

Analysis of inverse stochastic resonance and the long-term firing of Hodgkin-Huxley neurons with Gaussian white noise  

NASA Astrophysics Data System (ADS)

In order to explain the occurrence of a minimum in firing rate which occurs for certain mean input levels ? as noise level ? increases (inverse stochastic resonance, ISR) in Hodgkin-Huxley (HH) systems, we analyze the underlying transitions from a stable equilibrium point to limit cycle and vice-versa. For a value of ? at which ISR is pronounced, properties of the corresponding stable equilibrium point are found. A linearized approximation around this point has oscillatory solutions from whose maxima spikes tend to occur. A one dimensional diffusion is also constructed for small noise. Properties of the basin of attraction of the limit cycle (spike) are investigated heuristically. Long term trials of duration 500000 ms are carried out for values of ? from 0 to 2.0. The graph of mean spike count versus ? is divided into 4 regions R1,…,R4, where R3 contains the minimum associated with ISR. In R1 transitions to the basin of attraction of the rest point are not observed until a small critical value of ?=? is reached, at the beginning of R2. The sudden decline in firing rate when ? is just greater than ? implies that there is only a small range of noise levels 0

Tuckwell, Henry C.; Jost, Jürgen

2012-11-01

168

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

PubMed Central

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.

Xiang, Yun; Shen, Jun

2011-01-01

169

Radiosurgery for vestibular schwannomas.  

PubMed

This article investigates the role of radiosurgery and stereotactic radiotherapy in the management of vestibular schwannomas (VS), reviewing the authors' own prospective cohort and the current literature. For patients with large Stage IV VS (according to the Koos classification), a combined approach with deliberate partial microsurgical removal followed by radiosurgery to the residual tumor is proposed. The authors' cohort is unique with respect to the size of the population and the length of the follow-up, and demonstrates the efficacy and safety of VS radiosurgery, with particular regard to its high rate of hearing preservation. PMID:24093570

Régis, Jean; Carron, Romain; Delsanti, Christine; Porcheron, Denis; Thomassin, Jean-Marc; Murracciole, Xavier; Roche, Pierre-Hugues

2013-08-02

170

Vestibular responses to sound.  

PubMed

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

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

2005-04-01

171

Vestibular-evoked myogenic potentials in vestibular migraine  

Microsoft Academic Search

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

Bernhard Baier; N. Stieber; M. Dieterich

2009-01-01

172

Modelling the vestibular head tilt response.  

PubMed

This paper attempts to verify the existence of potentially diagnostically significant periodic signals thought to exist in recordings of neural activity originating from the vestibular nerve, following a single tilt of the head. It then attempts to find the physiological basis of this signal, in particular focusing on the mechanical response of the vestibular system. Simple mechanical models of the semi circular canals having angular velocities applied to them were looked at. A simple single canal model was simulated using CFX software. Finally, a simple model of all three canals with elastic duct walls and a moving cupula was constructed. Pressure waves within the canals were simulated using water hammer or pressure transient theory. In particular, it was investigated whether pressure waves within the utricle following a square pulse angular velocity applied to the canal(s) may be responsible for quasi-periodic oscillatory signals. The simulations showed that there are no pressure waves resonating within the canals following a square pulse angular velocity applied to the canal(s). The results show that the oscillatory signals are most likely not mechanical in origin. It was concluded that further investigation is required. PMID:15920988

Heibert, D; Lithgow, B

2005-03-01

173

Vestibular modulation of spatial perception.  

PubMed

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

Ferrè, Elisa R; Longo, Matthew R; Fiori, Federico; Haggard, Patrick

2013-10-10

174

Vestibular modulation of spatial perception  

PubMed Central

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

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

2013-01-01

175

Vestibular schwannoma surgery and headache.  

PubMed

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

Levo, H; Blomstedt, G; Pyykkö, I

2000-01-01

176

Intrinsic Firing Dynamics of Vestibular Nucleus Neurons  

Microsoft Academic Search

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

Chris Sekirnjak

2002-01-01

177

RECORDING OF VESTIBULAR EVOKED MYOGENIC POTENTIALS  

Microsoft Academic Search

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

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

178

Modeling the vestibular evoked myogenic potential  

Microsoft Academic Search

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

Bernd Lütkenhöner; Wolfgang Stoll; Türker Basel

2010-01-01

179

Physiological basis for enduring vestibular symptoms  

PubMed Central

Four examples of patients who sustained a vestibular insult and did not fully recover over a prolonged period are described. The reasons for this failure of compensation are discussed in relation to the experimental literature, particularly that concerning the importance of extra-vestibular inputs upon the vestibular system. Images

Rudge, R; Chambers, BR

1982-01-01

180

Procedures for restoring vestibular disorders  

PubMed Central

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

Walther, Leif Erik

2005-01-01

181

Theoretical analysis of destabilization resonances in time-delayed stochastic second-order dynamical systems and some implications for human motor control  

NASA Astrophysics Data System (ADS)

A linear stochastic delay differential equation of second order is studied that can be regarded as a Kramers model with time delay. An analytical expression for the stationary probability density is derived in terms of a Gaussian distribution. In particular, the variance as a function of the time delay is computed analytically for several parameter regimes. Strikingly, in the parameter regime close to the parameter regime in which the deterministic system exhibits Hopf bifurcations, we find that the variance as a function of the time delay exhibits a sequence of pronounced peaks. These peaks are interpreted as delay-induced destabilization resonances arising from oscillatory ghost instabilities. On the basis of the obtained theoretical findings, reinterpretations of previous human motor control studies and predictions for future human motor control studies are provided.

Patanarapeelert, K.; Frank, T. D.; Friedrich, R.; Beek, P. J.; Tang, I. M.

2006-02-01

182

Stereotactic radiotherapy for vestibular schwannoma.  

PubMed

Vestibular schwannomas are benign tumors of the Schwann cells of the eighth (VIII) cranial nerve. Precision radiotherapy techniques used to manage these tumors include stereotactic radiotherapy (SRT), which can be delivered with either a conventional or hypofractionated regimen. The radio-biologic rationale and reported clinical outcomes of patients treated with SRT are reviewed. PMID:19751870

Sweeney, Patrick; Yajnik, Santosh; Hartsell, William; Bovis, George; Venkatesan, Jagannath

2009-08-01

183

The Vestibular Implant: Quo Vadis?  

PubMed Central

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

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

2011-01-01

184

Ocular vestibular evoked myogenic potentials produced by impulsive lateral acceleration in unilateral vestibular dysfunction  

Microsoft Academic Search

ObjectiveTo deduce the connectivity underlying ocular vestibular evoked myogenic potentials (OVEMPs) recorded from two sites and produced by lateral transmastoid stimulation in patients with unilateral vestibular dysfunction.

Sendhil Govender; Sally M. Rosengren; Neil P. McAngus Todd; James G. Colebatch

2011-01-01

185

Flocculectomy and unit activity in the vestibular nuclei during visual-vestibular interactions  

Microsoft Academic Search

Activity of neurons in the vestibular nuclei of alert monkeys was recorded extracellularly after total unilateral and bilateral flocculectomy and partial paraflocculectomy. Type 1 horizontal cells that were encountered after flocculectomy responded to visual and vestibular stimuli and to conflict stimulation, i.e., to rotation in a subject-stationary visual surround, as do vestibular neurons in the normal animal. The major difference

W. Waespe; B. Cohen

1983-01-01

186

CGRP Expression in the Vestibular Periphery after Transient Blockage of Bilateral Vestibular Input  

Microsoft Academic Search

This study aimed to establish an animal model of reversible bilateral vestibular disorders that is suitable for examining the mechanisms of vestibular plasticity, and to observe the changes in the plasticity of vestibular efferent systems. Tetrodotoxin (TTX) was infused continuously for 7 days into the bilateral perilymph of guinea pig cochlea. We assessed the vestibulo-ocular reflex (VOR) for evaluating the

Hirotaka Hara; Kenji Takeno; Hiroaki Shimogori; Hiroshi Yamashita

2005-01-01

187

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

Microsoft Academic Search

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

Christian Beier; Heinz-Jürgen Steinhoff

2006-01-01

188

The increase of gravitational-wave interferometer sensitivity by employing stochastic resonance mechanism in nonlinear white-light cavity  

Microsoft Academic Search

We consider a nonlinear white-light cavity (WLC), operating in gravitational-wave (GW) interferometer arm. By using coupled-wave equations for nonlinear waves, we analyze nonlinear resonance and obtain a simple asymptotic equation for calculating of WLC output phase shift, when the operation point is placed very close to instability point. In a standard nonlinear cavity it would require the instability of laser

G. G. Karapetyan

2004-01-01

189

Resonance  

NSDL National Science Digital Library

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

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

2011-07-20

190

A possible mechanism of stochastic resonance in the light of an extra-classical receptive field model of retinal ganglion cells.  

PubMed

Traditionally the intensity discontinuities in an image are detected as zero-crossings of the second derivative with the help of a Laplacian of Gaussian (LOG) operator that models the receptive field of retinal Ganglion cells. Such zero-crossings supposedly form a raw primal sketch edge map of the external world in the primary visual cortex of the brain. Based on a new operator which is a linear combination of the LOG and a Dirac-delta function that models the extra-classical receptive field of the ganglion cells, we find that zero-crossing points thus generated, store in presence of noise, apart from the edge information, the shading information of the image in the form of density variation of these points. We have also shown that an optimal image contrast produces best mapping of the shading information to such zero-crossing density variation for a given amount of noise contamination. Furthermore, we have observed that an optimal amount of noise contamination reproduces the minimum optimal contrast and hence gives rise to the best representation of the original image. We show that this phenomenon is similar in nature to that of stochastic resonance phenomenon observed in psychophysical experiments. PMID:19373486

Ghosh, Kuntal; Sarkar, Sandip; Bhaumik, Kamales

2009-04-17

191

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

SciTech Connect

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

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

2010-05-15

192

Morphological Studies of the Vestibular Nerve.  

National Technical Information Service (NTIS)

The anatomy of the intratemporal part of the vestibular nerve in man, and the possible age related degenerative changes in the nerve were studied. The form and structure of the vestibular ganglion was studied with the light microscope. A numerical analysi...

B. Bergstroem

1973-01-01

193

Virtual reality in vestibular assessment and rehabilitation  

Microsoft Academic Search

Previous experiences on vestibular compensation showed that multisensorial stimulations affect postural unbalance recovery. Virtual Environment (VE) exposure seems very useful in vestibular rehabilitation, since the experience gained during VE exposure is transferable to the real world. The rearrangement of the hierarchy of the postural cues was evaluated in 105 patients affected by visual, labyrinthic and somatosensory pathology in normal conditions

S. Girolamo; W. Nardo; P. Picciotti; G. Paludetti; F. Ottaviani; O. Chiavola

1999-01-01

194

Vestibular tests in the selection of cosmonauts  

NASA Astrophysics Data System (ADS)

Vestibulo-vegetative disorders in cosmonauts and astronauts occurring during space flight compel otolaryngologists to search for vestibular tests enabling a precise evaluation of the activity of the vestibular apparatus and showing disposition to motion sickness. Otoneurological investigation of Polish candidates for cosmonaut status consisted of the following vestibular tests: caloric, rotatory, optokinetic, swinging torsion, statokinesimetric and vestibulo-vegetative. The value of various vestibular tests for aviation and space medicine is presented in this paper, taking into account the results of investigations of the equilibrium system with the group of pilots selected for space flight as well as extensive experience with candidates for the air service and also trained pilots and patients. The relatively frequent lack of correlation between the results of the applied tests, which renders difficult the proper evaluation of the equilibrium system, is emphasized in the paper. Finally, the results of investigations of acute habituation of the vestibular apparatus are discussed.

Kubiczkowa, Janusza

195

Significance of Vestibular Evoked Myogenic Potentials in Peripheral Vestibulopathy  

Microsoft Academic Search

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

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

196

Vestibular findings in professional divers.  

PubMed

The purpose of the present study was to investigate possible inner ear changes related to professional diving, by the documentation of auditory and vestibular function in 13 asymptomatic professional divers and 12 nondiver controls. A higher average pure tone hearing threshold, although of no clinical significance, was found in the study group (8.53 +/- 4.85 versus 6.67 +/- 3.54 dB hearing level, p = .04). In the vestibular evaluation, the smooth harmonic acceleration test phase leads for 0.01, 0.02, and 0.04 Hz were significantly lower in the divers (0.01 Hz, 38.46 degrees +/- 7.15 degrees versus 45.83 degrees +/- 9.02 degrees, p = .02; 0.02 Hz, 21.08 degrees +/- 5.19 +/- versus 25.17 degrees +/- 5.78 degrees, p = .05: 0.04 Hz, 12.38 degrees +/- 3.69 degrees versus 14.25 degrees +/- 3.14 degrees, p = .05). We suggest that the lower smooth harmonic acceleration phase values found in the professional divers, reflecting longer vestibulo-ocular reflex primary time constants and enhancement of the velocity storage mechanism, are the result of a habituation process that augments the low-frequency response of the canal-ocular system. PMID:11219519

Sharoni, Z; Shupak, A; Spitzer, O; Nachum, Z; Gadoth, N

2001-02-01

197

Vestibular stimulation modifies the body schema.  

PubMed

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

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

2012-04-26

198

Vestibular rehabilitation for patients with agoraphobia and vestibular dysfunction: a pilot study  

Microsoft Academic Search

This study examined whether physical therapy with vestibular rehabilitation exercises would benefit patients with agoraphobia and vestibular dysfunction. Nine patients went through a 2-week no-treatment baseline phase, a 4-week behavioral treatment phase focusing on self-directed exposure, and an 8–12-week vestibular rehabilitation phase (weekly sessions). On the main outcome measure, clinical global impressions (CGI) ratings of severity, behavioral treatment was accompanied

Rolf G Jacob; Susan L Whitney; Gail Detweiler-Shostak; Joseph M Furman

2001-01-01

199

The effects of the "vestibular sedative" drug, Flunarizine upon the vestibular and oculomotor systems.  

PubMed Central

The effects of the "vestibular sedative" drug Flunarizine upon the oculomotor functions of pursuit and voluntary saccades and upon the vestibular response (to rotational stimuli) were assessed in twenty volunteer subjects. The study was then extended to three patients with chronic imbalance of central origin who had reported a beneficial symptomatic response to the drug. Three of the volunteer subjects were found to have a directional preponderance (presumed to arise from peripheral dysfunction). In the remaining seventeen normal subjects Flunarizine was found to reduce the amplitudes of fast phases of vestibular nystagmus. The directional preponderance in the other three subjects was redressed through production of fast phases which were of lower and more uniform amplitude. In the patients, in addition to a reduction in fast phase amplitude, there was a reduction or abolition of after nystagmus. In no case was any reduction in slow phase velocity observed. Pursuit and voluntary saccades were unaffected by the drug. It was concluded, on the basis that the fast phases of nystagmus are centrally generated, that Flunarizine has a central action rather than a depressant effect upon the vestibular end organ. In view of known oculomotor physiology and pharmacology it is proposed that vestibular sedatives act by depression of Type II vestibular neurons, and modification of the functional relationships between the vestibular nuclei, the perihypoglossal nuclei and the flocculus of the cerebellum. A trial of vestibular active drug is indicated particularly in patients in whom asymmetry of the vestibular response and/or abnormal after nystagmus is demonstrated.

Ell, J; Gresty, M

1983-01-01

200

Properties of rectified averaging of an evoked-type signal: theory and application to the vestibular-evoked myogenic potential  

Microsoft Academic Search

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

J. G. Colebatch

2009-01-01

201

Vestibular Efferent Activity in Squirrel Monkeys.  

National Technical Information Service (NTIS)

All vertebrates are endowed with a vestibular efferent system (EVS) consisting of somata within the central nervous system with long axons exiting the brain to innervate the labyrinth. Behaviorally relevant stimuli related to feeding and/or aggressive beh...

S. M. Highstein

1990-01-01

202

Stimulus Processing in Vestibular Hair Cells.  

National Technical Information Service (NTIS)

Mammalian vestibular organs have two types of sensory cells: Type I and Type II hair cells. To compare signalling properties of these cell types, they are studied in vitro, where their voltage responses (receptor potentials) to controlled manipulations of...

R. A. Eatock

1989-01-01

203

Calcified vestibular schwannoma in the cerebellopontine angle.  

PubMed

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

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

2007-09-19

204

Resonance  

NSDL National Science Digital Library

All About Circuits is a website that âÂÂprovides 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).

Kuphaldt, Tony R.

2008-07-07

205

Stochastic Programming  

Microsoft Academic Search

\\u000a With the requirement of considering randomness, different types of stochastic programming have been developed to suit the\\u000a different purposes of management. The first type of stochastic programming is the expected value model, which optimizes the expected objective functions subject to some expected constraints. The second, chance-constrained programming, was pioneered by Charnes and Cooper [37] as a means of handling uncertainty

Baoding Liu

206

Reciprocal inhibitory visual-vestibular interaction. Visual motion stimulation deactivates the parieto-insular vestibular cortex.  

PubMed

The vestibular system--a sensor of head accelerations--cannot detect self-motion at constant velocity and thus requires supplementary visual information. The perception of self-motion during constant velocity movement is completely dependent on visually induced vection. This can be linear vection or circular vection (CV). CV is induced by large-field visual motion stimulation during which the stationary subject perceives the moving surroundings as being stable and himself as being moved. To determine the unknown cortical visual-vestibular interaction during CV, we conducted a PET activation study on CV in 10 human volunteers. The PET images of cortical areas activated during visual motion stimulation without CV were compared with those with CV. Hitherto, CV was explained neurophysiologically by visual-vestibular convergence with activation of the vestibular nuclei, thalamic subnuclei and vestibular cortex. If CV were mediated by the vestibular cortex, one would expect that an adequate visual motion stimulus would activate both the visual and vestibular cortex. Contrary to this expectation, it was shown for the first time that visual motion stimulation with CV not only activates a medial parieto-occipital visual area bilaterally, separate from middle temporal/medial superior temporal areas, it also simultaneously deactivates the parieto-insular vestibular cortex. There was a positive correlation between the perceived intensity of CV and relative changes in regional CBF in parietal and occipital areas. These findings support a new functional interpretation: reciprocal inhibitory visual-vestibular interaction as a multisensory mechanism for self-motion perception. Inhibitory visual-vestibular interaction might protect visual perception of self-motion from potential vestibular mismatches caused by involuntary head accelerations during locomotion, and this would allow the dominant sensorial weight during self-motion perception to shift from one sensory modality to the other. PMID:9762962

Brandt, T; Bartenstein, P; Janek, A; Dieterich, M

1998-09-01

207

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

PubMed Central

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

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

2012-01-01

208

[Vestibular neuronitis: pathophysiology, diagnosis and treatment].  

PubMed

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

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

209

On the recall of vestibular sensations.  

PubMed

Functional neuroimaging studies on the recall or imagination of a distinctive task in the motor network or of sensations in sensory systems (visual, acoustic, nociceptive, gustatory, and olfactory) demonstrated that the respective primary cortex is often involved in the mental imagery process. Our aim was to examine this phenomenon in the vestibular system using fMRI. Sixteen healthy subjects were asked to remember the feeling of a rotatory chair procedure in contrast to an identical situation at rest. Shortly afterwards they were asked to recall the vestibular experience in a 1.5-T scanner. The resulting activations were then compared with the responses of a galvanic vestibular control experiment and a rest condition. The vestibular recall showed significant bihemispheric activations in the inferior frontal gyri, the anterior operculum, the middle cingulate, the putamen, the globus pallidus, the premotor motor cortex, and the anterior insula. We found activations in regions known to play a role in spatial referencing, motor programs, and attention in the recall of vestibular sensations. But important known relay stations for the cortical processing of vestibular information showed neither relevant activations nor deactivations. PMID:22367249

zu Eulenburg, Peter; Müller-Forell, W; Dieterich, M

2012-02-25

210

Cervical and ocular vestibular-evoked myogenic potentials in acute vestibular neuritis  

Microsoft Academic Search

ObjectivesTo clarify the origin and afferent pathways of short-latency ocular vestibular-evoked myogenic potential (oVEMP) in response to air-conducted sound (ACS), we evaluated cervical (cVEMP) and ocular VEMPs in patients with vestibular neuritis (VN).

Byoung-Soo Shin; Sun-Young Oh; Ji Soo Kim; Tae-Woo Kim; Man-Wook Seo; Hyung Lee; Young-Ae Park

211

Responses of primary vestibular neurons to galvanic vestibular stimulation (GVS) in the anaesthetised guinea pig  

Microsoft Academic Search

Previous studies in humans and animals which have shown that DC galvanic vestibular stimulation (GVS) induces horizontal and torsional eye movements have been interpreted as being due to a preferential activation of primary vestibular afferents innervating the horizontal semicircular canals and otoliths by GVS. The present study sought to determine in guinea pigs whether GVS does indeed selectively activate primary

Juno Kim; Ian S. Curthoys

2004-01-01

212

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

PubMed Central

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.

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

2012-01-01

213

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

PubMed

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

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

2012-09-06

214

Crystallisation pattern of vestibular mucus and its relation to vestibular electrical resistance in cycling sow.  

PubMed

Changes in the genital mucus around the oestrus are used by different diagnostic methods to determine optimal fertilisation time. In the current study, the authors evaluated the different arborisation patterns found in vestibular mucus, and also established its relationship with vestibular resistance changes during oestrus. Thirty multiparous sows were checked by transrectal ultrasonography to determine ovulation time every 12 hours. Vestibular resistance was measured with a commercial resistance probe, and vestibular mucus ferning was also evaluated every 12 hours during the oestrus. Significant changes (P < 0.05) in vestibular resistance were detected, registering high variation among individuals. Maximum resistance data was reached between 12 and 24 hours after ovulation time in 83 per cent of the sows. Crystallisation samples were classified into three different patterns according to the fern-like crystal degree. Arborisation peak occurred from 48 to 36 hours before the moment of ovulation, when vestibular resistance values increased gradually. In the optimal insemination moment, vestibular resistance increased significantly (P < 0.05) and vestibular mucus showed a low crystallisation pattern (P < 0.05). Combining several methods to measure genital mucus changes may predict the ovulation time and the best insemination moment. PMID:22922708

Luño, V; Gil, L; Jerez, R A; Malo, C; Galé, I; de Blas, I

2012-08-24

215

Pharmacotherapy of vestibular disorders and nystagmus.  

PubMed

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

Strupp, Michael; Kremmyda, Olympia; Brandt, Thomas

2013-09-21

216

Otolith-Canal Convergence in Vestibular Nuclei Neurons.  

National Technical Information Service (NTIS)

During manned spaceflight, acute vestibular disturbances often occur, leading to physical duress and a loss of performance. Vestibular adaptation to the weightless environment follows within two to three days yet the mechanisms responsible for the disturb...

J. D. Dickman

1996-01-01

217

Aging effect on galvanic vestibular-evoked myogenic potentials  

Microsoft Academic Search

ObjectiveThis study compared the characteristic parameters of vestibular-evoked myogenic potentials (VEMPs) via galvanic vestibular stimulation (GVS) in healthy subjects of various ages to measure the effect of aging on GVS-VEMPs.

Chih-Ming Chang; Po-Wen Cheng; Yi-Ho Young

2010-01-01

218

Neurohumoral Reactions to Long-Term Vestibular Stimulation in Man.  

National Technical Information Service (NTIS)

Neuroendocrine metabolism regulation during vestibular stimulation studies in man are wide-spread in gravitational physiology and space medicine in the recent past. As a rule, these investigations are associated with vestibular stimulation for only severa...

I. A. Nichiporuk A. N. Rapotkov O. I. Orlov A. I. Grigoriev

1993-01-01

219

Stochastic process in quantum optics  

SciTech Connect

The case of a two-state atom immersed in nearly monochromatic, nearly resonant radiation is considered. The radiation has a finite bandwidth. Collisional effects are also included. Time evolution equations of quantum excitation are presented. Examples of the stochastic processes are provided by showing the fluctuation of the coefficients of these equations. (WRF)

Shore, B.W.

1985-01-01

220

Stochastic cell.  

PubMed

Accumulating experimental evidence of stochasticity, self-organization and abrupt non-linear transitions underlying the dynamics of cellular structure and function is increasingly more consistent with the concepts and models of phase transitions, critical phenomena and non-linear thermodynamics rather than with the conventional clockwork description of the cell. The novel emerging image of the stochastic cell suggests that familiar and convenient classico-mechanical interpretations may be limiting our ability to understand the behavior of biological systems and calls for active exploration of alternative interpretational frameworks. PMID:16036564

Kurakin, Alexei

2005-02-01

221

Tone burst–galvanic ratio of vestibular evoked myogenic potential amplitudes: A new parameter of vestibular evoked myogenic potential?  

Microsoft Academic Search

ObjectiveTo clarify whether the ratio of tone burst vestibular evoked myogenic potential (VEMP) amplitude to galvanic (electric) VEMP amplitude can be a useful indicator of peripheral vestibular disorders, especially labyrinthine disorders.

Toshihisa Murofushi; Shinichi Iwasaki; Hidenori Ozeki; Munetaka Ushio; Yasuhiro Chihara

2007-01-01

222

Hippocampal Spatial Representations Require Vestibular Input  

PubMed Central

The hippocampal formation is essential for forming declarative representations of the relationships among multiple stimuli. The rodent hippocampal formation, including the entorhinal cortex and sub-icular complex, is critical for spatial memory. Two classes of hippocampal neurons fire in relation to spatial features. Place cells collectively map spatial locations, with each cell firing only when the animal occupies that cell’s “place field,” a particular subregion of the larger environment. Head direction (HD) cells encode directional heading, with each HD cell firing when the rat’s head is oriented in that cell’s particular “preferred firing direction.” Both landmarks and internal cues (e.g., vestibular, motor efference copy) influence place and HD cell activity. However, as is the case for navigation, landmarks are believed to exert greater influence over place and HD cell activity. Here we show that temporary inactivation of the vestibular system led to the disruption of location-specific firing in hippocampal place cells and direction-specific discharge of postsubicular HD cells, without altering motor function. Place and HD cell activity recovered over a time course similar to that of the restoration of vestibular function. These results indicate that vestibular signals provide an important influence over the expression of hippocampal spatial representations, and may explain the navigational deficits of humans with vestibular dysfunction.

Stackman, Robert W.; Clark, Ann S.; Taube, Jeffrey S.

2007-01-01

223

Visual-vestibular conflict induced by virtual reality in humans  

Microsoft Academic Search

Conflicting inputs from visual and vestibular afferents produce motion sickness and postural instability. However, the relationship of visual and vestibular inputs to each other remains obscure. In this study, we examined the development of subjective sickness- and balance-related symptoms and objective equilibrium ataxia induced by visual–vestibular conflict (VVC) stimulation using virtual reality. The subjective symptoms evaluated by Graybiel's and Hamilton's

Hironori Akiduki; Suetaka Nishiike; Hiroshi Watanabe; Katsunori Matsuoka; Takeshi Kubo; Noriaki Takeda

2003-01-01

224

How Actions Alter Sensory Processing Reafference in the Vestibular System  

Microsoft Academic Search

Our vestibular organs are simultaneously activated by our own actions as well as by stimulation from the external world. The ability to distinguish sensory inputs that are a consequence of our own actions (vestibular reafference) from those that result from changes in the external world (vestibular exafference) is essential for perceptual stability and accurate motor control. Recent work in our

Kathleen E. Cullen; Jessica X. Brooks; Soroush G. Sadeghi

225

Vestibular rehabilitation using a wide field of view virtual environment  

Microsoft Academic Search

This paper presents a theoretical justification for using a wide field of view (FOV) virtual reality display system for use in vestibular rehabilitation. A wide FOV environment offers some unique features that may be beneficial to vestibular rehabilitation. Primarily, optic flow information extracted from the periphery may be critical for recalibrating the sensory processes used by people with vestibular disorders.

P. J. Sparto; J. M. Furman; S. L. Whitney; L. F. Hodges; M. S. Redfern

2004-01-01

226

Gastric related neurons in the rat medial vestibular nucleus  

Microsoft Academic Search

Some structural and functional peculiarities of the rat vestibular nuclei neurones involved in realisation of vestibular-gastrointestinal reflectory reactions were studied. After microinjection of a horseradish peroxidase solution in the `gastric' area of the nucleus tractus solitarius, retrogradely-labelled cell bodies were found in caudal part of the medial vestibular nucleus. Electrical stimulation of these neurons resulted in the decrease of gastric

V. G. Aleksandrov; V. A. Bagaev; A. D. Nozdrachev

1998-01-01

227

Vestibular-evoked myogenic potentials in three patients with large vestibular aqueduct.  

PubMed

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

Sheykholeslami, Kianoush; Schmerber, Sébastien; Habiby Kermany, Mohammad; Kaga, Kimitaka

2004-04-01

228

Galvanic ocular vestibular evoked myogenic potentials provide new insight into vestibulo-ocular reflexes and unilateral vestibular loss  

Microsoft Academic Search

ObjectiveSynchronous extraocular muscle activity can be recorded from around the eyes at the beginning of a vestibular-evoked eye movement (ocular vestibular evoked myogenic potentials, OVEMPs). As galvanic vestibular stimulation (GVS) evokes the vestibulo-ocular reflex, we wished to investigate GVS-evoked OVEMPs.

Sally M. Rosengren; Peter Jombik; G. Michael Halmagyi; James G. Colebatch

2009-01-01

229

Stochastic cooling  

SciTech Connect

Stochastic cooling is the damping of betatron oscillations and momentum spread of a particle beam by a feedback system. In its simplest form, a pickup electrode detects the transverse positions or momenta of particles in a storage ring, and the signal produced is amplified and applied downstream to a kicker. The time delay of the cable and electronics is designed to match the transit time of particles along the arc of the storage ring between the pickup and kicker so that an individual particle receives the amplified version of the signal it produced at the pick-up. If there were only a single particle in the ring, it is obvious that betatron oscillations and momentum offset could be damped. However, in addition to its own signal, a particle receives signals from other beam particles. In the limit of an infinite number of particles, no damping could be achieved; we have Liouville's theorem with constant density of the phase space fluid. For a finite, albeit large number of particles, there remains a residue of the single particle damping which is of practical use in accumulating low phase space density beams of particles such as antiprotons. It was the realization of this fact that led to the invention of stochastic cooling by S. van der Meer in 1968. Since its conception, stochastic cooling has been the subject of much theoretical and experimental work. The earliest experiments were performed at the ISR in 1974, with the subsequent ICE studies firmly establishing the stochastic cooling technique. This work directly led to the design and construction of the Antiproton Accumulator at CERN and the beginnings of p anti p colliding beam physics at the SPS. Experiments in stochastic cooling have been performed at Fermilab in collaboration with LBL, and a design is currently under development for a anti p accumulator for the Tevatron.

Bisognano, J.; Leemann, C.

1982-03-01

230

Vestibular failure in children with congenital deafness.  

PubMed

Congenitally deaf infants and children commonly suffer vestibular failure in both ears, and impairment of postural control, locomotion, and gait. The development of gross motor functions, such as head control, sitting, and walking is likely to be delayed, but fine motor function is usually preserved unless disorders of the central nervous system are present. These children can eventually catch up with their normal peers in terms of development and growth as a result of central vestibular compensation. The visual and somatosensory systems, pyramidal and extrapyramidal motor system (cerebellum, basal ganglia, cerebrum) and intellectual development, compensate for vestibular failure in infants and children with congenitally hypoactive or absent function of the semicircular canals and otolith organs. PMID:18821229

Kaga, Kimitaka; Shinjo, Yukiko; Jin, Yulian; Takegoshi, Hideki

2008-09-01

231

Head injury and blast exposure: vestibular consequences.  

PubMed

Young adults are more likely to suffer blast injury and traumatic brain injury (TBI) than other age groups. This article reviews the literature on the vestibular consequences of blast exposure and TBI and concussion. In addition, the vestibular test findings obtained from 31 veterans with a history of blast exposure and/or mild TBI are presented. The authors discuss loss of horizontal semicircular canal function and postural instability related to head injury. Preliminary data suggest the novel theory that otolith organs are uniquely vulnerable to head injury and blast exposure. PMID:21474007

Akin, Faith W; Murnane, Owen D

2011-04-01

232

QB1 - Stochastic Gene Regulation  

SciTech Connect

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

Munsky, Brian [Los Alamos National Laboratory

2012-07-23

233

Adaptation to Vestibular Disorientation. Viii. 'Coriolis'. Vestibular Stimulation and the Influence of Different Visual Surrounds.  

National Technical Information Service (NTIS)

Disorientation caused by 'Coriolis' vestibular reactions has been cited frequently as a significant factor in flying safety. In addition, personnel who maintain rotating radar towers may also be adversely affected by 'Coriolis' problems. In the study, the...

W. E. Collins

1967-01-01

234

Effects of EAS cochlear implantation surgery on vestibular function.  

PubMed

Abstract 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

Tsukada, Keita; Moteki, Hideaki; Fukuoka, Hisakuni; Iwasaki, Satoshi; Usami, Shin-Ichi

2013-09-06

235

Interactions between Stress and Vestibular Compensation - A Review  

PubMed Central

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

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

2012-01-01

236

Viruses and vestibular neuritis: review of human and animal studies.  

PubMed

There is increasing evidence in man and animals that several human viruses can damage the vestibular labyrinth. Clinical and serologic studies of patients with vestibular neuritis suggest that the viruses may play a role in the pathogenesis of this disease. Temporal bone studies of patients dying after vestibular neuritis have found maximal damage in the distal branches of the vestibular nerve. These changes are felt to be consistent with a viral etiology. No satisfactory animal viral model of vestibular neuritis currently exists. However, animal studies have demonstrated that several human viruses including rubeola, herpes simplex, reovirus, mouse and guinea pig cytomegalovirus, and neurotropic strains of influenza A and mumps virus, can infect the vestibular nerve and the vestibular membranous labyrinth. PMID:8470506

Davis, L E

1993-01-01

237

Vestibular rehabilitation in elderly patients with central vestibular dysfunction: a prospective, randomized pilot study.  

PubMed

For the vestibular system, aging is associated with degenerated otoconia and loss of hair cells, vestibular afferents, and cells in the vestibular nuclei. Further neurodegenerative processes involve cortical, extrapyramidal motor, and cerebellar structures. Dizziness is quite common in the elderly, limiting their mobility and activities. The role of vestibular rehabilitation in these patients is controversial. The present prospective, randomized, preliminary investigation aimed to compare the effect of a 6-week posturography-assisted vestibular rehabilitation protocol (30 min a week) combined with a home-based exercise program (group A, 14 randomly assigned elderly patients) with the same home-based exercise program alone (group B, 14 randomly assigned elderly patients) for treating dizziness due to central vestibular dysfunction in elderly patients. The outcomes were analyzed using the 25-item Dizziness Handicap Inventory (DHI) and computerized posturography. After rehabilitation, group A scored significantly better in the DHI for the functional (p?=?0.0016) and emotional (p?=?0.01) domains and total score (p?=?0.001); only the emotional domain improved significantly in group B (p?=?0.038). Group A improved significantly in some posturographic parameters in the motor tests (reaction time, movement velocity, and endpoint excursion), while group B experienced more limited improvements. Our preliminary results with a program of posturography-assisted vestibular rehabilitation, and home-based exercises are more promising than with home-based exercises alone. A new study on a larger series of elderly patients with central vestibular dysfunctions is currently underway at Padova University, considering the effect of a protocol involving rehabilitation with computerized posturography alone and the relationship between outcomes and the duration of rehabilitation programs. PMID:23179254

Marioni, Gino; Fermo, Salvatore; Lionello, Marco; Fasanaro, Elena; Giacomelli, Luciano; Zanon, Stefania; Staffieri, Claudia; Dall'igna, Franco; Manzato, Enzo; Staffieri, Alberto

2012-11-22

238

A Stochastic Model of the Earth-Moon Tidal Evolution Accounting for Cyclic Variations of Resonant Properties of the Ocean: an Asymptotic Solution  

Microsoft Academic Search

A stochastic model of the Earth-Moon tidal evolution taking into account fluctuating effects of the continental drift is described. The above effects caused by alternation of periods of consolidation and disintegration of continents are specified as a combination of cyclic variations and superimposed random perturbations of the ocean eigenoscillation spectrum. The solution is found with use of one-mode and multi-mode

B. A. Kagan; N. B. Maslova

1994-01-01

239

A stochastic model of the Earth-Moon tidal evolution accounting for cyclic variations of resonant properties of the ocean: an asymptotic solution  

Microsoft Academic Search

A stochastic model of the Earth-Moon tidal evolution taking into account fluctuating effects of the continental drift is described. The above effects caused by alternation of periods of consolidation and disintegration of continents are specified as a combination of cyclic variations and superimposed random perturbations of the ocean eigenoscillation spectrum. The solution is found with use of one-mode and multi-mode

B. A. Kagan; N. B. Maslova

1994-01-01

240

Stochastic transparency.  

PubMed

Stochastic transparency provides a unified approach to order-independent transparency, antialiasing, and deep shadow maps. It augments screen-door transparency using a random sub-pixel stipple pattern, where each fragment of transparent geometry covers a random subset of pixel samples of size proportional to alpha. This results in correct alpha-blended colors on average, in a single render pass with fixed memory size and no sorting, but introduces noise. We reduce this noise by an alpha correction pass, and by an accumulation pass that uses a stochastic shadow map from the camera. At the pixel level, the algorithm does not branch and contains no read-modify-write loops, other than traditional z-buffer blend operations. This makes it an excellent match for modern massively parallel GPU hardware. Stochastic transparency is very simple to implement and supports all types of transparent geometry, able without coding for special cases to mix hair, smoke, foliage, windows, and transparent cloth in a single scene. PMID:20921587

Enderton, Eric; Sintorn, Erik; Shirley, Peter; Luebke, David

2011-08-01

241

Vestibular evoked myogenic potentials of undiagnosed dizziness  

Microsoft Academic Search

ObjectiveRecording of vestibular evoked myogenic potentials (VEMP) can facilitate the evaluation of otolith function. The dizziness caused by otolith lesions is not completely understood. To clarify which symptoms of dizziness originate from the otolith organs, we examined the relationship between symptoms and VEMP results in patients with undiagnosed dizziness.

Toru Seo; Atsushi Miyamoto; Michiko Node; Masafumi Sakagami

2008-01-01

242

Vestibular Evoked Myogenic Potentials in Preterm Infants  

Microsoft Academic Search

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

Seyra Erbek; Zeynel Gokmen; Servet Ozkiraz; Selim S. Erbek; Aylin Tarcan; Levent N. Ozluoglu

2009-01-01

243

Deconvolution of the vestibular evoked myogenic potential  

Microsoft Academic Search

The vestibular evoked myogenic potential (VEMP) and the associated variance modulation can be understood by a convolution model. Two functions of time are incorporated into the model: the motor unit action potential (MUAP) of a “mean” motor unit, and the temporal modulation of the MUAP rate of all contributing motor units, briefly called rate modulation. The latter is the function

Bernd Lütkenhöner; Türker Basel

244

Vesibulotoxicity and Management of Vestibular Disorders  

ERIC Educational Resources Information Center

The toxicity of certain aminoglycoside antibiotics for vestibular hair cells has been used to special advantage in the treatment of Meniere's disease. Intratympanic (middle ear) injections of these drugs are being increasingly used to control vertigo in this disorder when it has not responded to medical therapy. The mechanisms by which these drugs…

Carey, John P.

2005-01-01

245

Intrinsic firing dynamics of vestibular nucleus neurons.  

PubMed

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 neurons in the medial vestibular nucleus substantially influence firing response dynamics. Hyperpolarizing and depolarizing inputs evoked a markedly heterogenous range of firing responses. Strong postinhibitory rebound firing (PRF) was associated with strong firing rate adaptation (FRA) and occurred preferentially in large multipolar neurons. In response to sinusoidally modulated input current, these neurons showed a pronounced phase lead with respect to neurons lacking strong PRF and FRA. A combination of the hyperpolarization-activated H current and slow potassium currents contributed to PRF, whereas FRA was predominantly mediated by slow potassium currents. An integrate-and-fire-type model, which simulated FRA and PRF, reproduced the phase lead observed in large neurons and showed that adaptation currents were primarily responsible for variations in response phase. We conclude that the heterogeneity of firing dynamics observed in response to head movements in intact animals reflects intrinsic as well as circuit properties. PMID:11896148

Sekirnjak, Chris; du Lac, Sascha

2002-03-15

246

Vestibular dysfunction in Gulf War syndrome  

Microsoft Academic Search

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

PETER S. ROLAND; ROBERT W. HALEY; WENDY YELLIN; KRIS OWENS; ANGELA G. SHOUP

2000-01-01

247

Postural Compensation for Unilateral Vestibular Loss  

PubMed Central

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

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

2011-01-01

248

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

PubMed Central

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

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

2011-01-01

249

Expression of Calcitonin Gene-Related Peptide in Efferent Vestibular System and Vestibular Nucleus in Rats with Motion Sickness  

PubMed Central

Motion sickness presents a challenge due to its high incidence and unknown pathogenesis although it is a known fact that a functioning vestibular system is essential for the perception of motion sickness. Recent studies show that the efferent vestibular neurons contain calcitonin gene-related peptide (CGRP). It is a possibility that the CGRP immunoreactivity (CGRPi) fibers of the efferent vestibular system modulate primary afferent input into the central nervous system; thus, making it likely that CGRP plays a key role in motion sickness. To elucidate the relationship between motion sickness and CGRP, the effects of CGRP on the vestibular efferent nucleus and the vestibular nucleus were investigated in rats with motion sickness. Methods An animal model of motion sickness was created by subjecting rats to rotary stimulation for 30 minutes via a trapezoidal stimulation pattern. The number of CGRPi neurons in the vestibular efferent nucleus at the level of the facial nerve genu and the expression level of CGRPi in the vestibular nucleus of rats were measured. Using the ABC method of immunohistochemistry technique, measurements were taken before and after rotary stimulation. The effects of anisodamine on the expression of CGRP in the vestibular efferent nucleus and the vestibular nucleus of rats with motion sickness were also investigated. Results and Discussion Both the number of CGRPi neurons in the vestibular efferent nucleus and expression level in the vestibular nucleus increased significantly in rats with motion sickness compared to that of controls. The increase of CGRP expression in rats subjected to rotary stimulation 3 times was greater than those having only one-time stimulation. Administration of anisodamine decreased the expression of CGRP within the vestibular efferent nucleus and the vestibular nucleus in rats subjected to rotary stimulation. In conclusion, CGRP possibly plays a role in motion sickness and its mechanism merits further investigation.

Xiaocheng, Wang; Zhaohui, Shi; Junhui, Xue; Lei, Zhang; Lining, Feng; Zuoming, Zhang

2012-01-01

250

Frequency-independent synaptic transmission supports a linear vestibular behavior  

PubMed Central

Summary The vestibular system is responsible for transforming head motion into precise eye, head, and body movements that rapidly stabilize gaze and posture. How do central excitatory synapses mediate behavioral outputs accurately matched to sensory inputs over a wide dynamic range? Here we demonstrate that vestibular afferent synapses in vitro express frequency-independent transmission that spans their in vivo dynamic range (5 – 150 spikes/s). As a result, the synaptic charge transfer per unit time is linearly related to vestibular afferent activity in both projection and intrinsic neurons of the vestibular nuclei. Neither postsynaptic glutamate receptor desensitization nor saturation affect the relative amplitude or frequency-independence of steady-state transmission. Finally, we show that vestibular nucleus neurons can transduce synaptic inputs into linear changes in firing rate output, without relying on one-to-one calyceal transmission. These data provide a physiological basis for the remarkable linearity of vestibular reflexes.

Bagnall, Martha W.; McElvain, Lauren E.; Faulstich, Michael; du Lac, Sascha

2008-01-01

251

A Novel V- Silicone Vestibular Stent: Preventing Vestibular Stenosis and Preserving Nasal Valves  

PubMed Central

This report presents a novel style of placing nasal stents. Patients undergoing surgical procedures in the region of nasal vestibule and nasal valves are at risk of developing vestibular stenosis and lifelong problems with the external and internal nasal valves; sequels of the repair. The objective of the report is to demonstrate a simple and successful method of an inverted V- Stent placement to prevent potential complication of vestibular stenosis and nasal valve compromise later in life. Following a fall on a sharp edge of a metallic bed, a sixteen month old child with a deep lacerated nasal wound extending from the collumellar base toward the tip of the nose underwent surgical exploration and repair of the nasal vestibule and nasal cavity. A soft silicone stent fashioned as inverted V was placed bilaterally. The child made a remarkable recovery with no evidence of vestibular stenosis or nasal valve abnormalities. In patients with nasal trauma involving the nasal vestibule and internal and external nasal valves stent placement avoids sequels, adhesions, contractures, synechia vestibular stenosis and fibrosis involving these anatomical structures. The advantages of the described V- stents over the traditional readymade ridged nasal stents, tubing’s and composite aural grafts are: a) technical simplicity of use, b) safety, c) less morbidity, d) more comfortable, and e) economical. To our knowledge, this is the first report of such a stent for prevention of vestibular stenosis and preserving nasal valves.

Bassam, Wameedh AL; Bhargava, Deepa; Al-Abri, Rashid

2012-01-01

252

Orbital Spaceflight During Pregnancy Shapes Function of Mammalian Vestibular System  

Microsoft Academic Search

Pregnant rats were flown on the NASA Space Shuttle during the early developmental period of their fetuses' vestibular apparatus and onset of vestibular function. The authors report that prenatal spaceflight exposure shapes vestibular-mediated behavior and central morphology. Postflight testing revealed (a) delayed onset of body righting responses, (b) cardiac deceleration (bradycardia) to 70o head-up roll, (c) decreased branching of gravistatic

April E. Ronca; Bernd Fritzsch; Laura L. Bruce; Jeffrey R. Alberts

2008-01-01

253

Spatial symmetries in vestibular projections to the uvula-nodulus  

Microsoft Academic Search

The discharge of secondary vestibular neurons relays the activity of the vestibular endorgans, occasioned by movements in\\u000a three-dimensional physical space. At a slightly higher level of analysis, the discharge of each secondary vestibular neuron\\u000a participates in a multifiber projection or pathway from primary afferents via the secondary neurons to another neuronal population.\\u000a The logical organization of this projection determines whether

Isaac Z. Foster; Douglas A. Hanes; Neal H. Barmack; Gin Mccollum

2007-01-01

254

Internal models and neural computation in the vestibular system  

Microsoft Academic Search

The vestibular system is vital for motor control and spatial self-motion perception. Afferents from the otolith organs and\\u000a the semicircular canals converge with optokinetic, somatosensory and motor-related signals in the vestibular nuclei, which\\u000a are reciprocally interconnected with the vestibulocerebellar cortex and deep cerebellar nuclei. Here, we review the properties\\u000a of the many cell types in the vestibular nuclei, as well

Andrea M. GreenDora; Dora E. Angelaki

2010-01-01

255

Enlarged vestibular aqueduct in pediatric SNHL  

PubMed Central

Objective Comparison of the Cincinnati criteria (midpoint >0.9 mm or operculum >1.9 mm) to the Valvassori criterion (midpoint ? 1.5 mm) for enlarged vestibular aqueduct (EVA) in pediatric cochlear implant patients. Study Design Cohort study Subjects 130 Pediatric cochlear implant recipients. Methods We reviewed temporal bone CT scans to measure the vestibular aqueduct midpoint and opercular width. Results The Cincinnati criteria identified 44% of patients with EVA versus 16% with the Valvassori criterion (P<0.01). Of those with EVA, 45% were unilateral and 55% were bilateral using Cincinnati criteria; 64% were unilateral and 36% bilateral using Valvassori criterion (P<0.01). The Cincinnati criteria diagnosed 70 ears with EVA classified as normal using the Valvassori criterion (P<0.01);59 lacked another medical explanation for their hearing loss. Conclusion The Cincinnati criteria identified a large percentage of pediatric cochlear implant patients with EVA who might otherwise have no known etiology for their deafness.

Dewan, Karuna; Wippold, Franz J.; Lieu, Judith E C

2010-01-01

256

[The vestibular system: from structure to function].  

PubMed

The two vestibular receptors, right and left, hidden in the petrous part of the temporal bone with the cochlear receptors, receive information from angular and linear movements of the head and transform them into a nerve message sent to the nuclei of the brainstem, which are connected directly on the one hand to the oculomotor nuclei, at the origin of the oculovestibular reflex (induction of nystagmus), and on the other hand, to the spinal motor neurons, at the origin of the vestibulospinal reflex. These reflexes are associated with responses to visual and somaesthetic information for maintenance or return to the standing position, which characterises the function of equilibrium. Vertigo and disorders of balance reflect a conflict of information between these two labyrinths, or between the vestibular apparatus and the messages issued by other captors, and sometimes also dysfunction of central nervous system treatment of information or a lesion of the effector motor systems. PMID:8178092

Collard, M

1994-02-01

257

Direction Specific Biases in Human Visual and Vestibular Heading Perception  

PubMed Central

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

Crane, Benjamin T.

2012-01-01

258

Gastric related neurons in the rat medial vestibular nucleus.  

PubMed

Some structural and functional peculiarities of the rat vestibular nuclei neurones involved in realisation of vestibular-gastrointestinal reflectory reactions were studied. After microinjection of a horseradish peroxidase solution in the 'gastric' area of the nucleus tractus solitarius, retrogradely-labelled cell bodies were found in caudal part of the medial vestibular nucleus. Electrical stimulation of these neurons resulted in the decrease of gastric tone. The respiratory arrest was registered simultaneously. The results suggest that activation of the identified vestibular neurons can induce coordinated changes in visceral systems which are peculiar to a vomiting reaction. PMID:9696067

Aleksandrov, V G; Bagaev, V A; Nozdrachev, A D

1998-06-26

259

Vestibular Evoked Myogenic Potentials in Newborns  

Microsoft Academic Search

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

Chun-Nan Chen; Shou-Jen Wang; Chi-Te Wang; Wu-Shiun Hsieh; Yi-Ho Young

2007-01-01

260

Wireless Vestibular Evoked Myogenic Potentials System  

Microsoft Academic Search

Existing commercial vestibular evoked myogenic potentials (VEMP) testing systems are cabled systems, which impede certain experiments, particularly those that involve motion and rotation of the patient. This paper presents an autonomous wireless system to record VEMPs. The system uses IMEC's 60 muW 60 nV\\/VHz biopotential readout front-end to extract the electromyogram (EMG). It uses IMEC's low power processing and wireless

T. Torfs; R. F. Yazicioglu; P. Merken; B. Gyselinckx; R. Puers; R. Vanspauwen; F. L. Wuyts; C. Van Hoof

2007-01-01

261

The reaction time to vestibular stimuli  

Microsoft Academic Search

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

B. Baxter; R. C. Travis

1938-01-01

262

Gamma knife radiosurgery for vestibular schwannomas.  

PubMed

The purpose of this study was to analyze tumor control and possible complications of gamma knife radiosurgery (GKRS) in patients with vestibular schwannomas using low marginal doses and conformal multiple shots to fit irregular tumor shapes. The authors evaluated 152 patients with more than 5 years of follow-up. Marginal doses were 9-15 Gy (median 12 Gy), with corresponding treatment volumes ranging from 0.1 to 18.7 cm3 (median 2.0 cm3). The number of isocenters varied from 2 to 24 shots (median 9 shots). The actuarial tumor control rates were 94% at 5 years and 92.4% at 8 years. Larger tumors (p < 0.0001) and those in younger patients (p = 0.018) tended to recur significantly more often. Useful hearing, facial and trigeminal functions were preserved at 71, 100 and 97.4%, respectively. Seventeen percent of all patients developed transient dizziness, with dizziness persisting in 2% of the total. Fifty-six other patients not included in the long-term evaluation consecutively underwent caloric testing and static stabilometry as well as neurological examinations to evaluate vestibular function in detail, both before and after GKRS. The results revealed 90% of the patients to have already developed vestibular dysfunction prior to the treatment despite reported symptoms of dizziness. GKRS did not significantly affect vestibular function. Hydrocephalus was recognized in 5.3% of all patients, and tended to occur in cases with larger tumors (p = 0.0024). GKRS provides a safe and effective therapy for small to medium-sized tumors. However, indications for larger tumors must be carefully considered, as they are more difficult to control and liable to produce ataxia due to transient expansion. PMID:18948719

Fukuoka, Seiji; Takanashi, Masami; Hojyo, Atsufumi; Konishi, Masanori; Tanaka, Chiharu; Nakamura, Hirohiko

2009-01-01

263

Growth factor treatment enhances vestibular hair cell renewal and results in improved vestibular function  

PubMed Central

The vestibules of adult guinea pigs were lesioned with gentamicin and then treated with perilymphatic infusion of either of two growth factor mixtures (i.e., GF I or GF II). GF I contained transforming growth factor ? (TGF?), insulin-like growth factor type one (IGF-1), and retinoic acid (RA), whereas GF II contained those three factors and brain-derived neurotrophic factor. Treatment with GF I significantly enhanced vestibular hair cell renewal in ototoxin-damaged utricles and the maturation of stereociliary bundle morphology. The addition of brain-derived neurotrophic factor to the GF II infusion mixture resulted in the return of type 1 vestibular hair cells in ototoxin-damaged cristae, and improved vestibular function. These results suggest that growth factor therapy may be an effective treatment for balance disorders that are the result of hair cell dysfunction and/or loss.

Kopke, Richard D.; Jackson, Ronald L.; Li, Geming; Rasmussen, Mark D.; Hoffer, Michael E.; Frenz, Dorothy A.; Costello, Michael; Schultheiss, Peter; Van de Water, Thomas R.

2001-01-01

264

Vestibular evoked myogenic potentials to sound and vibration: characteristics in vestibular migraine that enable separation from Menière’s disease  

Microsoft Academic Search

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

Rachael L Taylor; Alessandro S Zagami; William PR Gibson; Deborah A Black; Michael G Halmagyi; Miriam S Welgampola

2012-01-01

265

Stochastic Cooling  

SciTech Connect

Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.

Blaskiewicz, M.

2011-01-01

266

Radiotherapy for Vestibular Schwannomas: A Critical Review  

SciTech Connect

Vestibular schwannomas are slow-growing tumors of the myelin-forming cells that cover cranial nerve VIII. The treatment options for patients with vestibular schwannoma include active observation, surgical management, and radiotherapy. However, the optimal treatment choice remains controversial. We have reviewed the available data and summarized the radiotherapeutic options, including single-session stereotactic radiosurgery, fractionated conventional radiotherapy, fractionated stereotactic radiotherapy, and proton beam therapy. The comparisons of the various radiotherapy modalities have been based on single-institution experiences, which have shown excellent tumor control rates of 91-100%. Both stereotactic radiosurgery and fractionated stereotactic radiotherapy have successfully improved cranial nerve V and VII preservation to >95%. The mixed data regarding the ideal hearing preservation therapy, inherent biases in patient selection, and differences in outcome analysis have made the comparison across radiotherapeutic modalities difficult. Early experience using proton therapy for vestibular schwannoma treatment demonstrated local control rates of 84-100% but disappointing hearing preservation rates of 33-42%. Efforts to improve radiotherapy delivery will focus on refined dosimetry with the goal of reducing the dose to the critical structures. As future randomized trials are unlikely, we suggest regimented pre- and post-treatment assessments, including validated evaluations of cranial nerves V, VII, and VIII, and quality of life assessments with long-term prospective follow-up. The results from such trials will enhance the understanding of therapy outcomes and improve our ability to inform patients.

Murphy, Erin S., E-mail: murphye3@ccf.or [Department of Radiation Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH (United States); Suh, John H. [Department of Radiation Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH (United States)

2011-03-15

267

[Vestibular and cochlear manifestations in Fabry's disease].  

PubMed

Anderson-Fabry's disease corresponds to an inherited disorder transmitted by an X-linked recessive gene. The disease is caused by an alpha-galactosidase deficiency leading to an abnormal glycosphingolipid metabolism, resulting in glycosphingolipids deposits all over the body. The disease affects all organs over the body and can be responsible for central nervous system or renal failure, heart attack, which can lead for early death in absence of diagnosis and treatment. In addition to these life-threatening manifestations, other problems which may have a profound impact on quality of life, such as hearing loss, have been relatively neglected. Thus, a large proportion of patients with Fabry's disease suffer from sensorineural hearing loss, with both progressive hearing impairment and sudden deafness, and peripheral vestibular deficits with dizziness and vertigo. The exact pathophysiologic mechanism(s) of those otological complications is still studied, but both cochleo-vestibular disorder and vascular origin seems to be involved. For many years, only symptomatic treatment has been available. For the past ten years, the introduction of enzyme replacement therapy with recombinant agalsidase-? or -? provides new prospect for these patients, decreasing the risk of complications. Still on study, it may also be active both on hearing loss and vestibular disturbances. PMID:21211674

Malinvaud, D; Germain, D P; Benistan, K; Bonfils, P

2010-12-01

268

Spatial and temporal characteristics of vestibular convergence.  

PubMed

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

McArthur, K L; Zakir, M; Haque, A; Dickman, J D

2011-07-01

269

Electrical vestibular stimulation and space motion sickness  

NASA Astrophysics Data System (ADS)

Electrical vestibular stimulation (EVS) in dynamic balance condition was studied in order to search for a new provocative test of space motion sickness (SMS). SMS is usually attributed to a sensory conflict caused by exposure to microgravity. Vestibular information is conflicting but also unusual and insignificant. EVS is in accordance with this feature because it is not the adequate stimulus of the vestibular receptors. EVS was achieved by means of binaural electrical stimulation. Effects of EVS were potentiated by compelling the subject to maintain dynamic balance on a seesaw. The quantification of this function was performed before, during and after EVS in order to investigate a possible relationship between objective consequences of EVS i.e. dynamic balance disturbances, and the discomfort experienced by the subjects. Dynamic balancing skill was statistically worsened during EVS. Moreover EVS evoked subjective symptoms of SMS in 17 out of the 30 subjects examined. During EVS in eyes open conditions, the subjects who encountered the strongest discomfort, presented the most disturbed dynamic balance, evidencing a relationship between the level of discomfort and the imbalance arising from EVS. This method could thus constitute an interesting basis of SMS ground-based test.

Severac, Alexandra

270

'PREHAB': Vestibular prehabilitation to ameliorate the effect of a sudden vestibular loss.  

PubMed

A sudden unilateral loss or impairment of vestibular function causes vertigo, dizziness and impaired postural function. In most occasions, everyday activities supported or not by vestibular rehabilitation programs will promote compensation and the symptoms subside. As the compensatory process requires sensory input, matching performed motor activity, both motor learning of exercises and matching to sensory input are required. If there is a simultaneous cerebellar lesion found during surgery of the posterior cranial fossa, there may be a risk of a combined vestibulo-cerebellar lesion, with reduced compensatory abilities and with prolonged or sometimes permanent disability. On the other hand, a slow gradual loss of unilateral function occurring as the subject continues well everyday activities may go without any prominent symptoms. We therefore implemented a pre treatment plan before planned vestibular lesions (prehab). This was first done in subject undergoing gentamicin treatment for Meniere's disease (MD). Subjects perform vestibular exercises for 14 days before the first gentamicin installation and then continue doing so until free of symptoms. Most subjects would only experience slight dizziness while losing vestibular function. We then expanded the approach to patients with brainstem tumours requiring surgery but with remaining vestibular function to ease postoperative symptoms and reduce risk of combined cerebello-vestibular lesions. This patient group was given gentamicin installations trans-tympanically before tumour sugary and then underwent prehab. In all cases there was a caloric loss, loss of VOR evident in the head impulse tests, impaired subjective vertical and horizontal, and reduced caloric function induced by the pre-surgery gentamicin treatment. The prehab eliminated spontaneous and positional nystagmus, subjective symptoms, and postural function up before surgery and allowed for rapid postoperative recovery.The concept of 'pre-lesion rehabilitation' where training is introduced before a planned lesion and if possible paralleled with a gradual function loss expands the potential of rehabilitation. Here it was used for vestibular lesions but it is possible that similar approaches may be developed for other situations, which include foreseeable loss of function. PMID:22027076

Magnusson, Måns; Karlberg, Mikael; Tjernström, Fredrik

2011-01-01

271

Rats avoid high magnetic fields: dependence on an intact vestibular system  

PubMed Central

Summary HOUPT, T.A., J.A. CASSELL, C. RICCARDI, M.D. DENBLEYKER, A. HOOD, AND J.C. SMITH. Rats avoid high magnetic fields: dependence on an intact vestibular system. PHYSIOL BEHAV 00(0)000-000, 2006. High strength static magnetic fields are thought to be benign and largely undetectable by mammals. As magnetic resonance imaging (MRI) machines increase in strength, however, potential aversive effects may become clinically relevant. Here we report that rats find entry into a 14.1 T magnet aversive, and that they can detect and avoid entry into the magnet at a point where the magnetic field is 2 T or lower. Rats were trained to climb a ladder through the bore of a 14.1 T superconducting magnet. After their first climb into 14.1 T, most rats refused to re-enter the magnet or climb past the 2 T field line. This result was confirmed in a resistive magnet in which the magnetic field was varied from 1 to 14 T. Detection and avoidance required the vestibular apparatus of the inner ear, because labyrinthectomized rats readily traversed the magnet. The inner ear is a novel site for magnetic field transduction in mammals, but perturbation of the vestibular apparatus would be consistent with human reports of vertigo and nausea around high strength MRI machines.

Houpt, Thomas A.; Cassell, Jennifer A.; Riccardi, Christina; DenBleyker, Megan D.; Hood, Alison; Smith, James C.

2009-01-01

272

Applied Nonlinear Dynamics and Stochastic Systems Near The Millenium. Proceedings  

Microsoft Academic Search

These proceedings represent papers presented at the Applied Nonlinear Dynamics and Stochastic Systems conference held in San Diego, California in July 1997. The conference emphasized the applications of nonlinear dynamical systems theory in fields as diverse as neuroscience and biomedical engineering, fluid dynamics, chaos control, nonlinear signal\\/image processing, stochastic resonance, devices and nonlinear dynamics in socio-economic systems. There were 56

J. B. Kadtke; A. Bulsara

1997-01-01

273

Chronic Vestibulo-Ocular Reflexes Evoked by a Vestibular Prosthesis  

Microsoft Academic Search

We are developing prosthetics for patients suffering from peripheral vestibular dysfunction. We tested a sensory-replacement prosthesis that stimulates neurons innervating the vestibular system by providing chronic pulsatile stimulation to electrodes placed in monkeys' lateral semicircular canals, which were plugged bilaterally, and used head angular velocity to modulate the current pulse rate. As an encouraging finding, we observed vestibulo-ocular reflexes that

Daniel M. Merfeld; Csilla Haburcakova; Wangsong Gong; Richard F. Lewis

2007-01-01

274

Vestibular Evoked Myogenic Potentials in Patients with Idiopathic Bilateral Vestibulopathy  

Microsoft Academic Search

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

Masaki Matsuzaki; Toshihisa Murofushi

2001-01-01

275

Age-Related Changes in Vestibular Evoked Myogenic Potentials  

Microsoft Academic Search

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

Krister Brantberg; Kerstin Granath; Nadine Schart

2007-01-01

276

Dynamic tilt thresholds are reduced in vestibular migraine.  

PubMed

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

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

2011-01-01

277

Dynamic tilt thresholds are reduced in vestibular migraine  

PubMed Central

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

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

2013-01-01

278

Postural strategies associated with somatosensory and vestibular loss  

Microsoft Academic Search

This study examines the roles of somatosensory and vestibular information in the coordination of postural responses. The role of somatosensory information was examined by comparing postural responses of healthy control subjects prior to and following somatosensory loss due to hypoxic anesthesia of the feet and ankles. The role of vestibular information was evaluated by comparing the postural responses of control

F. B. Horak; L. M. Nashner; H. C. Diener

1990-01-01

279

A vestibular sensation: probabilistic approaches to spatial perception  

PubMed Central

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

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

2009-01-01

280

Presynaptic GABA(B) receptors decrease neurotransmitter release in vestibular nuclei neurons during vestibular compensation.  

PubMed

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

Shao, M; Reddaway, R; Hirsch, J C; Peusner, K D

2012-08-04

281

Postural and locomotor control in normal and vestibularly deficient mice  

PubMed Central

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

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

2004-01-01

282

Gait initiation characteristics in elderly patients with unilateral vestibular impairment.  

PubMed

The study tested the hypothesis that vestibular patients (n=14) with chronic unsteadiness caused by a documented peripheral unilateral vestibular dysfunction would display differences in muscular activation and movement pattern during gait initiation compared to age-, gender- and body-size-matched healthy Controls (n=14). The displacements of the whole body Center of Pressure (CoP) during the preparatory phase before the swing leg is lifted, were markedly different in vestibular patients. The backward shift during this phase was significantly smaller than in Controls, coupled with a larger secondary corrective forward shift of the CoP. Conversely, the CoP-shift in the M-L direction towards the stance leg was larger in the vestibular patients. Most vestibular patients lacked the anticipatory tibialis anterior (TA) burst, which normally is a prerequisite for the backward displacement of the CoP that precedes the forward movement. The vestibular patients displayed more pronounced TA-Gastrocnemius coactivation in the stance leg when the swing leg was lifted. The duration of the preparatory phase was significantly longer in vestibular patients than in Controls, with no time differences in the later gait initiation events. The vestibular patients started from a more symmetrical stance and with less M-L variation than the Controls. It is concluded that chronically impaired vestibular function leads to a different strategy to create forward momentum to the body. In addition, there is evidence that vestibular patients have diminished postural stability, or alternatively a more cautious behaviour, when initiating the second step. PMID:21450469

Henriksson, Marketta; Henriksson, Jan; Bergenius, Johan

2011-03-29

283

Vestibular activation by bone conducted sound  

PubMed Central

Objective: To examine the properties and potential clinical uses of myogenic potentials to bone conducted sound. Methods: Myogenic potentials were recorded from normal volunteers, using bone conducted tone bursts of 7 ms duration and 250–2000 Hz frequencies delivered over the mastoid processes by a B 71 clinical bone vibrator. Biphasic positive–negative (p1n1) responses were recorded from both sternocleidomastoid (SCM) muscles using averaged unrectified EMG. The best location for stimulus delivery, optimum stimulus frequency, stimulus thresholds, and the effect of aging on evoked response amplitudes and thresholds were systematically examined. Subjects with specific lesions were studied. Vestibular evoked myogenic potentials (VEMP) to air conducted 0.1 ms clicks, 7 ms/250–2000 Hz tones, and forehead taps were measured for comparison. Results: Bone conducted sound evoked short latency p1n1 responses in both SCM muscles. Ipsilateral responses occurred earlier and were usually larger. Mean (SD) p1 and n1 latencies were 13.6 (1.8) and 22.3 (1.2) ms ipsilaterally and 14.9 (2.1) and 23.7 (2.7) ms contralaterally. Stimuli of 250 Hz delivered over the mastoid process, posterosuperior to the external acoustic meatus, yielded the largest amplitude responses. Like VEMP in response to air conducted clicks and tones, p1n1 responses were absent ipsilaterally in subjects with selective vestibular neurectomy and preserved in those with severe sensorineural hearing loss. However, p1n1 responses were preserved in conductive hearing loss, whereas VEMP to air conducted sound were abolished or attenuated. Bone conducted response thresholds were 97.5 (3.9) dB SPL/30.5 dB HL, significantly lower than thresholds to air conducted clicks (131.7 (4.9) dB SPL/86.7 dB HL) and tones (114.0 (5.3) dB SPL/106 dB HL). Conclusions: Bone conducted sound evokes p1n1 responses (bone conducted VEMP) which are a useful measure of vestibular function, especially in the presence of conductive hearing loss. For a given perceptual intensity, bone conducted sound activates the vestibular apparatus more effectively than air conducted sound.

Welgampola, M; Rosengren, S; Halmagyi, G; Colebatch, J

2003-01-01

284

Stochasticity of comet P\\/Ge-Wang  

Microsoft Academic Search

Three comets are now known to be at or near the 1\\/1 resonance with Jupiter: P\\/Slaughter-Burnham, P\\/Boethin and P\\/Ge-Wang. Although details of the individual orbits differ, the three comets have very similar general dynamic behavior: their orbits show many transitions between the different types of resonant motion (satellite libration, anti-satellite libration and circulating motion). The stochastic character of such cometary

D. Benest; R. Gonczi

1994-01-01

285

Stochastic variational method for light unstable nuclei  

Microsoft Academic Search

We present a review of the recent application of the stochastic variational method with the correlated Gaussian basis to light unstable nuclei. It is also shown that the precise calculation of the bound-state energy can be used to determine resonance parameters by analytic continuation.

Y. Suzuki; N. Tanaka; K. Varga

1998-01-01

286

Colored Stochastic Petri Nets.  

National Technical Information Service (NTIS)

Colored stochastic Petri nets are presented as an extension of the stochastic Petri nets model in which the tokens, the transitions, and the corresponding probability measurement are colored. The development leads to a simplification of the basic model an...

A. Zenie

1986-01-01

287

Lectures in Stochastic Control.  

National Technical Information Service (NTIS)

Lectures introduce in a mathematically self-contained way several important topics of stochastic control both in discrete and continuous time. In particular, subjects such as stochastic LQ-problem, long run average cost problems, disorder problem, adaptiv...

J. Zabczyk

1983-01-01

288

Influence of galvanic vestibular stimulation on egocentric and object-based mental transformations  

Microsoft Academic Search

The vestibular system analyses angular and linear accelerations of the head that are important information for perceiving\\u000a the location of one’s own body in space. Vestibular stimulation and in particular galvanic vestibular stimulation (GVS) that\\u000a allow a systematic modification of vestibular signals has so far mainly been used to investigate vestibular influence on sensori-motor\\u000a integration in eye movements and postural

Bigna Lenggenhager; Christophe Lopez; Olaf Blanke

2008-01-01

289

InXuence of galvanic vestibular stimulation on egocentric and object-based mental transformations  

Microsoft Academic Search

The vestibular system analyses angular and lin- ear accelerations of the head that are important information for perceiving the location of one's own body in space. Vestibular stimulation and in particular galvanic vestibular stimulation (GVS) that allow a systematic modiWcation of vestibular signals has so far mainly been used to investigate vestibular inXuence on sensori-motor integration in eye movements and

Bigna Lenggenhager; Christophe Lopez; Olaf Blanke

290

Biomimetic smart sensors for autonomous robotic behavior II: vestibular processing  

NASA Astrophysics Data System (ADS)

Limited autonomous behaviors are fast becoming a critical capability in the field of robotics as robotic applications are used in more complicated and interactive environments. As additional sensory capabilities are added to robotic platforms, sensor fusion to enhance and facilitate autonomous behavior becomes increasingly important. Using biology as a model, the equivalent of a vestibular system needs to be created in order to orient the system within its environment and allow multi-modal sensor fusion. In mammals, the vestibular system plays a central role in physiological homeostasis and sensory information integration (Fuller et al, Neuroscience 129 (2004) 461-471). At the level of the Superior Colliculus in the brain, there is multimodal sensory integration across visual, auditory, somatosensory, and vestibular inputs (Wallace et al, J Neurophysiol 80 (1998) 1006-1010), with the vestibular component contributing a strong reference frame gating input. Using a simple model for the deep layers of the Superior Colliculus, an off-the-shelf 3-axis solid state gyroscope and accelerometer was used as the equivalent representation of the vestibular system. The acceleration and rotational measurements are used to determine the relationship between a local reference frame of a robotic platform (an iRobot Packbot®) and the inertial reference frame (the outside world), with the simulated vestibular input tightly coupled with the acoustic and optical inputs. Field testing of the robotic platform using acoustics to cue optical sensors coupled through a biomimetic vestibular model for "slew to cue" gunfire detection have shown great promise.

Xue, Shuwan; Deligeorges, Socrates; Soloway, Aaron; Lichtenstein, Lee; Gore, Tyler; Hubbard, Allyn

2009-05-01

291

Review of stochastic mechanics  

NASA Astrophysics Data System (ADS)

Stochastic mechanics is an interpretation of nonrelativistic quantum mechanics in which the trajectories of the configuration, described as a Markov stochastic process, are regarded as physically real. The natural stochastic generalization of classical variational principles leads to a derivation of the Schrödinger equation. A brief review of the successes and failures of the theory is given, with references.

Nelson, Edward

2012-05-01

292

Stochastic cooling in RHIC  

SciTech Connect

After the success of longitudinal stochastic cooling of bunched heavy ion beam in RHIC, transverse stochastic cooling in the vertical plane of Yellow ring was installed and is being commissioned with proton beam. This report presents the status of the effort and gives an estimate, based on simulation, of the RHIC luminosity with stochastic cooling in all planes.

Brennan,J.M.; Blaskiewicz, M. M.; Severino, F.

2009-05-04

293

Vestibular rehabilitation using a wide field of view virtual environment.  

PubMed

This paper presents a theoretical justification for using a wide field of view (FOV) virtual reality display system for use in vestibular rehabilitation. A wide FOV environment offers some unique features that may be beneficial to vestibular rehabilitation. Primarily, optic flow information extracted from the periphery may be critical for recalibrating the sensory processes used by people with vestibular disorders. If this hypothesis is correct, then wide FOV systems will have an advantage over narrow field of view input devices such as head mounted or desktop displays. Devices that we have incorporated into our system that are critical for monitoring improvement in this clinical population will also be described. PMID:17271394

Sparto, P J; Furman, J M; Whitney, S L; Hodges, L F; Redfern, M S

2004-01-01

294

Stochastic Gain in Population Dynamics  

NASA Astrophysics Data System (ADS)

We introduce an extension of the usual replicator dynamics to adaptive learning rates. We show that a population with a dynamic learning rate can gain an increased average payoff in transient phases and can also exploit external noise, leading the system away from the Nash equilibrium, in a resonancelike fashion. The payoff versus noise curve resembles the signal to noise ratio curve in stochastic resonance. Seen in this broad context, we introduce another mechanism that exploits fluctuations in order to improve properties of the system. Such a mechanism could be of particular interest in economic systems.

Traulsen, Arne; Röhl, Torsten; Schuster, Heinz Georg

2004-07-01

295

Internal models of self-motion: computations that suppress vestibular reafference in early vestibular processing  

Microsoft Academic Search

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

Kathleen E. CullenJessica; Jessica X. Brooks; Mohsen Jamali; Jerome Carriot; Corentin Massot

2011-01-01

296

Influence of Gravity on Vestibular Nystagmus in Humans.  

National Technical Information Service (NTIS)

Traditionally, the human vestibular system is tested by acceleration and deceleration in a rotating chair, simulating the horizontal semicircular canals. This kind of testing provides no information about the performance of the two pairs of vertical (ante...

E. Koenig D. Tweed M. Fetter D. Fischer H. Misslisch

1993-01-01

297

Spinal Effects of an Electrical Vestibular Stimulation in Man.  

National Technical Information Service (NTIS)

The effects of a bipolar and monaural electrical vestibular stimulation on the excitability of spinal reflexes (monosynaptic reflex of Hoffman) are studied. This stimulation causes an increase in amplitude of H-reflexes. The results demonstrate also a ref...

M. Lacour M. Bonnet J. P. Roll

1975-01-01

298

Development of vestibular evoked myogenic potentials in early life  

Microsoft Academic Search

ObjectiveThis study applied vestibular evoked myogenic potential (VEMP) test in full-term newborns younger than 2 weeks, to investigate the development and maturation of the sacculo-collic reflex in early life.

Yi-Ho Young; Chun-Nan Chen; Wu-Shiun Hsieh; Shou-Jen Wang

2009-01-01

299

A Manual for the Brief Vestibular Disorientation Test.  

National Technical Information Service (NTIS)

This report describes procedures for implementing the Brief Vestibular Disorientation Test (BVDT) which was designed to detect individuals with extreme reactivity to disorientation stress. The procedures are brief, simple to administer, and do not require...

R. K. Ambler F. E. Guedry

1978-01-01

300

Mutations of ESPN cause autosomal recessive deafness and vestibular dysfunction.  

PubMed

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

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

2004-08-01

301

Vestibular schwannoma, tinnitus and cellular telephones.  

PubMed

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 of VS was only found for the latter of the two time periods 1960-1979 and 1980-1998. For all other brain tumors taken together, the incidence significantly increased yearly by +0.80% (CI 0.59-1.02) for the time period 1960-1998, although the increase was only significant for benign tumors other than VS during 1960-1979. PMID:12629278

Hardell, Lennart; Hansson Mild, Kjell; Sandström, Monica; Carlberg, Michael; Hallquist, Arne; Påhlson, Anneli

302

Vestibular stimulation, spatial hemineglect and dysphasia, selective effects.  

PubMed

The selectivity of the effects of vestibular stimulation was investigated in a left brain-damaged patient suffering from right visuo-spatial hemineglect and severe dysplasia. Vestibular stimulation temporarily improved the former but not the latter disorder. These results support the view that this treatment improves hemineglect by a specific effect, running counter the rightward distortion of egocentric co-ordinates, rather than by a general hemispheric activation. PMID:8536486

Vallar, G; Papagno, C; Rusconi, M L; Bisiach, E

1995-09-01

303

Changes in the vestibular function during space flight.  

PubMed

An analysis of observations and investigations carried out in space flight has shown that some cosmonauts and astronauts have experienced vestibular disorders during the transition to weightlessness. Vestibular-sensory disorders include: Spatial illusions (the feelings of falling down, being in an upside-down position, the sensations of rotation of the craft or the body) and vertigo occurring during the onset of the orbital flight and head movements; Feelings, similar to those experienced in response to Coriolis accelerations on the Earth, which occasionally develop in weightlessness during the spacecraft rotation upon abrupt head and body movements and restrained feet; Feelings "of the load on the vestibular analyser which is unlike any Earth-bound effects" upon abrupt head movements during the first hours of an orbital flight and "a prolonged movement" during the switch-off of thrusters in weightlessness. Vestibular-vegetative disorders comprise a complex of symptoms similar to those of motion sickness: loss of appetite, stomach awareness (12%), hypersalination, nausea (9.6%) and vomiting (4.8%). Soviet studies suggest that the vestibular tolerance to the flight effects depends on the natural stability and training to the cumulative effect of adequate vestibular stimuli. This has been used in the development of the system of vestibular selection. Changes in the vestibular function seem to play the major role in the development of motion sickness in weightlessness, extra-labyrinthine factors being contributory. The current hypotheses have not yet been adequately confirmed in experiments. A detailed physiological analysis allows the conclusion that the decisive factor in the development of motion sickness may be the disturbance of the function of analysers responsible for spatial orientation which take the form of sensory conflicts as well as an altered reactivity of the organism due to the hemodynamic rearrangement. PMID:11887913

Gurovskiy, N N; Bryanov, I I; Yegorov, A D

304

Ocular vestibular evoked myogenic potentials in superior canal dehiscence  

Microsoft Academic Search

Objective:Patients with superior canal dehiscence (SCD) have large sound-evoked vestibular reflexes with pathologically low threshold. We wished to determine whether a recently discovered measure of the vestibulo-ocular reflex—the ocular vestibular evoked myogenic potential (OVEMP)—produced similar high-amplitude, low-threshold responses in SCD, and could differentiate patients with SCD from normal control patients.Methods:Nine patients with CT-confirmed SCD and 10 normal controls were stimulated

S M Rosengren; S T Aw; G M Halmagyi; N P McAngus Todd; J G Colebatch

2008-01-01

305

Vestibular evoked myogenic potentials: Past, present and future  

Microsoft Academic Search

Since the first description of sound-evoked short-latency myogenic reflexes recorded from neck muscles, vestibular evoked myogenic potentials (VEMPs) have become an important part of the neuro-otological test battery. VEMPs provide a means of assessing otolith function: stimulation of the vestibular system with air-conducted sound activates predominantly saccular afferents, while bone-conducted vibration activates a combination of saccular and utricular afferents. The

S. M. Rosengren; M. S. Welgampola; J. G. Colebatch

2010-01-01

306

Asymmetric vestibular evoked myogenic potentials in unilateral Menière patients  

Microsoft Academic Search

Vestibular evoked myogenic potentials (VEMPs) were measured in 22 unilateral Menière patients with monaural and binaural stimulation\\u000a with 250 and 500 Hz tone bursts. For all measurement situations significantly lower VEMP amplitudes were on average measured\\u000a at the affected side compared to the unaffected side. Unilateral Menière patients have, in contrast to normal subjects, asymmetric\\u000a VEMPs, indicating a permanently affected vestibular

C. M. Kingma; H. P. Wit

2011-01-01

307

Vestibular-evoked postsynaptic potentials in Deiters neurones  

Microsoft Academic Search

Stimulation of the vestibular nerve induced EPSPs monosynaptically in 29% of cat's Deiters neurones sampled on the ipsilateral side. These EPSPs started with latencies of 0.6–1.0 msec, rose sharply with a summit time of 0.5 msec and decayed exponentially with a time constant of 0.9–1.7 msec. Then amplitudes were graded finely according to the intensity of the vestibular nerve stimulation,

M. Ito; T. Hongo; Y. Okada

1969-01-01

308

Early and phasic cortical metabolic changes in vestibular neuritis onset.  

PubMed

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

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

2013-03-07

309

Excitatory amino acid receptors in normal and abnormal vestibular function  

Microsoft Academic Search

Although excitatory amino acid (FAA) receptors have been investigated extensively in the limbic system and neocortex, less\\u000a is known of the function of EAA receptors in the brainstem. A number of biochemical and electrophysiological studies suggest\\u000a that the synapse between the ipsilateral vestibular (VIIIth) nerve and the brainstem vestibular nucleus (VN) is mediated by\\u000a an EAA acting predominantly on kainate

Paul F. Smith; Catherine de Waele; Pierre-Paul Vidal; Cynthia L. Darlington

1991-01-01

310

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

PubMed

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

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

2011-08-26

311

Ocular vestibular-evoked myogenic potentials to bone-conducted vibration in superior vestibular neuritis show utricular function  

Microsoft Academic Search

ObjectiveTo determine whether the first negative component (n10) of the ocular vestibular-evoked myogenic potential (oVEMP) to bone-conducted vibration (BCV) is due primarily to activation of the utricular macula.

Leonardo Manzari; AnnaRita Tedesco; Ann M. Burgess; Ian S. Curthoys

2010-01-01

312

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

PubMed

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

Ferrè, Elisa R; Day, Brian L; Bottini, Gabriella; Haggard, Patrick

2013-07-01

313

The ocular vestibular-evoked myogenic potential to air-conducted sound; probable superior vestibular nerve origin  

Microsoft Academic Search

ObjectiveIntense air-conducted sound (ACS) elicits an ocular vestibular-evoked myogenic potential (oVEMP), and it has been suggested that it does so by stimulating saccular receptors and afferents in the inferior vestibular nerve and so activating a crossed sacculo-ocular pathway. Bone conducted vibration (BCV) also elicits an oVEMP probably by activating utricular receptors and a crossed utriculo-ocular pathway. Are there two separate

Ian S. Curthoys; Shinichi Iwasaki; Yasuhiro Chihara; Munetaka Ushio; Leigh A. McGarvie; Ann M. Burgess

2011-01-01

314

Vestibular and pulse-related modulation of skin sympathetic nerve activity during sinusoidal galvanic vestibular stimulation in human subjects  

Microsoft Academic Search

We have previously shown that sinusoidal galvanic vestibular stimulation (sGVS), a means of a selectively modulating vestibular\\u000a afferent input without affecting other inputs, can cause partial entrainment of muscle sympathetic nerve activity (MSNA).\\u000a Given that motion sickness causes sweating and pallor, we tested the hypothesis that sGVS also entrains skin sympathetic nerve\\u000a activity (SSNA), but that the optimal frequencies are

Cheree James; Alexandra Stathis; Vaughan G. Macefield

2010-01-01

315

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

Microsoft Academic Search

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

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

2011-01-01

316

Oculomotor disturbances during visual-vestibular interaction in Wallenberg's lateral medullary syndrome.  

PubMed

Transient and lasting oculomotor disturbances during visual-vestibular interaction are described in 9 patients with Wallenberg's lateral medullary syndrome. In all patients magnetic resonance imaging (MRI) demonstrated a single focal area of pathological signal intensity in the (dorso)-lateral medulla suggesting infarction. In 2 of these 9 patients and in 3 further patients with no medullary signs, the infarction involved the cerebellar territory of the posterior inferior cerebellar artery (PICA). Acutely, all patients with Wallenberg's syndrome (except 1) had saccadic lateropulsion and spontaneous nystagmus in light with the horizontal fast component beating to the contralateral normal side. The velocity of the slow drift to the side of the lesion was dependent on eye position and induced a characteristic asymmetry of the visually and vestibularly elicited slow eye movements. In most patients smooth pursuit, optokinetic nystagmus and visual suppression of the vestibulo-ocular reflex were still impaired when this spontaneous drift was minimal or absent. The oculomotor disturbances in patients with and without cerebellar infarction are compared. The following conclusions are made. (1) The spontaneous drift that is dependent on eye position is mostly created by 'ocular lateropulsion', that is, a tonic bias within the oculomotor system which may have several sources. (2) The abnormalities and asymmetries of oculomotor responses during visual-vestibular stimulation cannot solely be explained by this spontaneous drift and its interaction with otherwise normal eye movements. Instead, structures and pathways are damaged in Wallenberg's syndrome which mediate visual and/or motor signals important for the cerebellar control of visually-guided slow eye movements. (3) Damage to these pathways occurs in the lateral medulla, as the MRI findings show that in most patients the cerebellum is rarely involved, but no definite conclusion can be made as to which of the fibres travelling in the inferior peduncle to the cerebellum may be interrupted. PMID:2364271

Waespe, W; Wichmann, W

1990-06-01

317

Stochastic phase transition operator  

NASA Astrophysics Data System (ADS)

In this study a Markov operator is introduced that represents the density evolution of an impulse-driven stochastic biological oscillator. The operator’s stochastic kernel is constructed using the asymptotic expansion of stochastic processes instead of solving the Fokker-Planck equation. The Markov operator is shown to successfully approximate the density evolution of the biological oscillator considered. The response of the oscillator to both periodic and time-varying impulses can be analyzed using the operator’s transient and stationary properties. Furthermore, an unreported stochastic dynamic bifurcation for the biological oscillator is obtained by using the eigenvalues of the product of the Markov operators.

Yamanobe, Takanobu

2011-07-01

318

The appreciation of stochastic motion in particle accelerators  

SciTech Connect

A description is given of the analytic and numerical work, performed from July 1955 through August 1956, so as to develop, and then study, the process of making intense proton beams, suitable for colliding beams. It is shown how this investigation led, in a most natural way, to the realization that stochasticity can arise in a simple Hamiltonian system. Furthermore, the criterion for the onset of stochasticity was understood, and carefully studied, in two different situations. The first situation was the proposed (and subsequently used) ''stacking process'' for developing an intense beam, where stochasticity occurs as additional particles are added to the intense circulating beam. The second situation occurs when one seeks to develop ''stochastic accelerators'' in which particles are accelerated (continuously) by a collection of radio frequency systems. It was in the last connection that the well-known criterion for stochasticity, resonance overlap, was obtained.

Symon, Keith; Sessler, Andrew

2003-08-03

319

Sensitivity of Human Visual and Vestibular Cortical Regions to Egomotion-Compatible Visual Stimulation  

PubMed Central

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

Cardin, Velia

2010-01-01

320

Dorsal location of the cochlear nerve on vestibular schwannoma: preoperative evaluation, frequency, and functional outcome.  

PubMed

The cochlear nerve is most commonly located on the caudoventral portion of the capsule of vestibular schwannomas and rarely on the dorsal portion. In such a condition, total removal of the tumor without cochlear nerve dysfunction is extremely difficult. The purpose of our study was to identify the frequency of this anatomical condition and the status of postoperative cochlear nerve function; we also discuss the preoperative radiological findings. The study involved 114 patients with unilateral vestibular schwannomas operated on via a retrosigmoid (lateral suboccipital) approach. Locations of the cochlear nerve on the tumor capsule were ventral, dorsal, caudal, and rostral. Ventral and dorsal locations were further subdivided into rostral, middle, and caudal third of the tumor capsule. The postoperative cochlear nerve function and preoperative magnetic resonance (MR) findings were reviewed retrospectively. In 56 patients that had useful preoperative hearing, useful hearing was retained in 50.0% (28 of 56) of patients after surgery. The cochlear nerve was located on the dorsal portion of the tumor capsule in four patients (3.5%), and useful hearing was preserved in only one of these patients (25%) in whom the tumor had been partially resected. This tumor-nerve anatomical relationship was identified in all tumors of <2 cm at preoperative MR cisternography. MR cisternography has the potential to identify the tumor-nerve anatomical relationship, especially in small-sized tumors that usually require therapeutic intervention that ensures hearing preservation. Hence, careful evaluation of the preoperative MR cisternography is important in deciding the therapeutic indications. PMID:22696159

Nakamizo, Akira; Amano, Toshiyuki; Mizoguchi, Masahiro; Yoshimoto, Koji; Sasaki, Tomio

2012-06-14

321

Introduction to Focus Issue: nonlinear and stochastic physics in biology.  

PubMed

Frank Moss was a leading figure in the study of nonlinear and stochastic processes in biological systems. His work, particularly in the area of stochastic resonance, has been highly influential to the interdisciplinary scientific community. This Focus Issue pays tribute to Moss with articles that describe the most recent advances in the field he helped to create. In this Introduction, we review Moss's seminal scientific contributions and introduce the articles that make up this Focus Issue. PMID:22225375

Bahar, Sonya; Neiman, Alexander B; Jung, Peter; Kurths, Jürgen; Schimansky-Geier, Lutz; Showalter, Kenneth

2011-12-01

322

Multidimensional Stochastic Approximation Methods  

Microsoft Academic Search

Multidimensional stochastic approximation schemes are presented, and conditions are given for these schemes to converge a.s. (almost surely) to the solutions of $k$ stochastic equations in $k$ unknowns and to the point where a regression function in $k$ variables achieves its maximum.

Julius R. Blum

1954-01-01

323

Stochastic and Fuzzy PERT,  

National Technical Information Service (NTIS)

Network-planning techniques are considered, which are based on stochastic and fuzzy models of the activity durations. The stochastic versions of PERT are generally intractable, and they cannot be used to draw up tight plans for action. Fuzzy models are cl...

F. A. Lootsma

1988-01-01

324

Quantification of vestibular-induced eye movements in zebrafish larvae  

PubMed Central

Background Vestibular reflexes coordinate movements or sensory input with changes in body or head position. Vestibular-evoked responses that involve the extraocular muscles include the vestibulo-ocular reflex (VOR), a compensatory eye movement to stabilize retinal images. Although an angular VOR attributable to semicircular canal stimulation was reported to be absent in free-swimming zebrafish larvae, recent studies reveal that vestibular-induced eye movements can be evoked in zebrafish larvae by both static tilts and dynamic rotations that tilt the head with respect to gravity. Results We have determined herein the basis of sensitivity of the larval eye movements with respect to vestibular stimulus, developmental stage, and sensory receptors of the inner ear. For our experiments, video recordings of larvae rotated sinusoidally at 0.25 Hz were analyzed to quantitate eye movements under infrared illumination. We observed a robust response that appeared as early as 72 hours post fertilization (hpf), which increased in amplitude over time. Unlike rotation about an earth horizontal axis, rotation about an earth vertical axis at 0.25 Hz did not evoke eye movements. Moreover, vestibular-induced responses were absent in mutant cdh23 larvae and larvae lacking anterior otoliths. Conclusions Our results provide evidence for a functional vestibulo-oculomotor circuit in 72 hpf zebrafish larvae that relies upon sensory input from anterior/utricular otolith organs.

2010-01-01

325

Action Representation in Patients with Bilateral Vestibular Impairments  

PubMed Central

During mental actions subjects feel themselves performing a movement without any corresponding motor output. Although broad information is available regarding the influence of central lesions on action representation, little is known about how peripheral damages affect mental events. In the current study, we investigated whether lack of vestibular information influences action representation. Twelve healthy adults and twelve patients with bilateral vestibular damage actually performed and mentally simulated walking and drawing. The locomotor paths implied one (first walking task) and four (second walking task) changes in the walking direction. In the drawing task, participants drew on a sheet of paper a path that was similar to that of the second walking task. We recorded and compared between the two groups the timing of actual and mental movements. We found significant temporal discrepancies between actual and mental walking movements in the group of patients. Conversely, drawing actual and drawing mental durations were similar. For the control group, an isochrony between mental and actual movements was observed for the three tasks. This result denotes an inconsistency between action representation and action execution following vestibular damage, which is specific to walking movements, and emphasizes the role of the vestibular system upon mental states of actions. This observation may have important clinical implications. During action planning vestibular patients may overestimate the capacity of their motor system (imaging faster, executing slower) with harmful consequences for their health.

Demougeot, Laurent; Toupet, Michel; Van Nechel, Christian; Papaxanthis, Charalambos

2011-01-01

326

Large vestibular aqueduct syndrome: a case study.  

PubMed

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

Clark, Jackie L; Roeser, Ross J

327

Hemorrhagic Vestibular Schwannoma: Review of the Literature.  

PubMed

BACKGROUND: Clinically significant intratumoral hemorrhage historically has been reported in only a small fraction of vestibular schwannomas (VS). Patients with hemorrhagic VS are more likely to present with neurologic deficits and have worse outcomes than patients with nonhemorrhagic VS. The purpose of this study is to analyze characteristics that may predispose VS to hemorrhage and that may prove helpful in the management and treatment of VS. METHODS: A literature search was conducted using National Library of Medicine and National Institutes of Health databases to identify articles pertaining to intratumoral hemorrhage in VS. The authors selected 39 cases, described in 18 published articles, to review. RESULTS: Average patient age and tumor size in hemorrhagic cases of VS did not differ significantly from nonhemorrhagic cases of VS. Facial nerve dysfunction at presentation occurred with greater frequency in cases of hemorrhagic VS (33.3%) than in nonhemorrhagic VS (6.0%). Death occurred much more frequently in cases of hemorrhagic VS (10.0%) than in nonhemorrhagic VS (0.2%). Abnormality of tumor-associated vasculature was noted histologically in many cases, and a large number of the cases reported prior treatment by stereotactic radiosurgery. CONCLUSIONS: Understanding the origins and clinical implications of intratumoral hemorrhage in VS could potentially assist in clinical decision making and patient counseling. PMID:23454397

Niknafs, Yashar S; Wang, Anthony C; Than, Khoi D; Etame, Arnold B; Thompson, B Gregory; Sullivan, Stephen E

2013-02-27

328

Intracellular study of frog's vestibular neurons in relation to the labyrinth and spinal cord  

Microsoft Academic Search

Summary  Field and intracellular potentials were recorded in the vestibular nuclei of the frog following stimulation of the anterior branch of the ipsilateral vestibular nerve and the spinal cord. The field potential induced by stimulation of the vestibular nerve consisted of an early positive-negative wave followed by a slow negativity and that recorded during spinal cord stimulation was composed of an

W. PICECHT; A. Richter; S. Ozawa; H. Shimazu

1974-01-01

329

Effects of otitis media with effusion on the vestibular system in children  

Microsoft Academic Search

Middle ear effusion has been considered the most common cause of vestibular disturbance in children. However, there have been only a few studies on vestibular disturbance in children with otitis media with effusion. We studied the vestibular systems of 30 children with otitis media with effusion aged 8 to 13 years and compared the results with 15 age- and sex-matched

MEHMET KOYUNCU; M. MUH?TT?N SAKA; YÜCEL TANYER?; TEOMAN ?E?EN; RECEP ÜNAL; AT?LLA TEKAT; FAT?H YILMAZ

1999-01-01

330

Genetic polymorphisms for identifying individuals at risk for drug-induced vestibular dysfunction  

US Patent & Trademark Office Database

In this application is described the identification of genetic variants that contribute to susceptibility to drug-induced vestibular dysfunction, more particularly, GM-induced vestibular dysfunction. Methods, compositions and kits for determining whether an individual has susceptibility for drug-induced vestibular dysfunction are disclosed.

2011-05-03

331

Effects of otitis media with effusion on the vestibular system in children.  

PubMed

Middle ear effusion has been considered the most common cause of vestibular disturbance in children. However, there have been only a few studies on vestibular disturbance in children with otitis media with effusion. We studied the vestibular systems of 30 children with otitis media with effusion aged 8 to 13 years and compared the results with 15 age- and sex-matched controls. A questionnaire relating to vestibular disturbance was given to patients and their parents. Spontaneous nystagmus and positional nystagmus were recorded by electronystagmography as diagnostic tests of the vestibular system. Romberg's and past-pointing tests were performed on children with otitis media with effusion and controls. After vestibular tests were completed, myringotomy was performed, and a ventilation tube was inserted. The questionnaire and the vestibular tests were repeated after the operation and during the first month after surgery. Our study showed that there was a history of vestibular disturbance in 33% of children with otitis media with effusion. Electronystagmography and Romberg's test findings demonstrated that 33% of the children had vestibular dysfunction (p < 0.05). After myringotomy with ventilation tube insertion, vestibular test results returned to normal, and symptoms related to vestibular disturbance improved. These findings confirm the assumption that middle ear effusion may affect the vestibular system, which can be resolved after myringotomy with ventilation tube insertion. PMID:9914561

Koyuncu, M; Saka, M M; Tanyeri, Y; Se?en, T; Unal, R; Tekat, A; Yilmaz, F

1999-01-01

332

Cognitive-vestibular interactions: A review of patient difficulties and possible mechanisms  

Microsoft Academic Search

Cognitive deficits such as poor concentration and short-term memory loss are known by clinicians to occur frequently among patients with vestibular abnormalities. Although direct scientific study of such deficits has been limited, several types of investigations do lend weight to the existence of vestibular-cognitive effects. In this article we review a wide range of studies indicating a vestibular influence on

Douglas A. Hanes; Gin McCollum

2006-01-01

333

Extraterrestrial vestibular research, a new partial field of medical research into the human vestibular apparatus.  

PubMed

The first otologic professorial chair in the world was established by Politzer in Vienna as long ago as 1861. In 1914 an assistant of the 1st Vienna Ear Clinic with Politzer as its head, Barany, was awarded the Nobel Prize for Medicine for his fundamental investigations into the organ of equilibration and for his discovery of the caloric sensitivity of the semicircular canals. Since that time Barany is regarded as the founder of the physiology of the vestibular apparatus. During the period 1959 to 1963 a new conception of fundamental research into the vestibule was demanded and elaborated in Vienna with the postulate that, in all theoretical deliberations and practical experience, one should take into consideration that our experiments into the vestibule do not take place on a static platform but rather on a diversely moving one, namely the surface of the earth. This led to new findings in the field of research into the otolith apparatus. In 1962 it was discovered that the gravitation of the sun at the distance of earth-sun represents a supraliminal stimulus, namely both in the aphelion as well as in the perihelion position of the earth. In 1965 it was suggested in Vienna that a new branch of research into the vestibule should be established on an international level, the so-called extraterrestrial vestibular research. The importance of this new branch of research is discussed for all problems of orientation of human beings in space. PMID:12199253

Pichler, H J

1967-01-01

334

Stochastic dynamics of magnetosomes in cytoskeleton  

Microsoft Academic Search

Considered are the rotations of nanoscopic magnetic particles, magnetosomes, embedded in the cytoskeleton and subjected to the influence of an ac magnetic field and thermal noise. The rotations are studied within a double-well potential formed by mechanical and magnetic forces. It is shown that the motion of the magnetosomes meets the conditions of the so-called “stochastic resonance” under not-too-tight constraints

V. N. Binhi; D. S. Chernavskii

2005-01-01

335

Adaptively optimizing stochastic resonance in visual system  

Microsoft Academic Search

Recent psychophysics experiment has showed that the noise strength could affect the perceived image quality. This work gives an adaptive process for achieving the optimal perceived image quality in a simple image perception array, which is a simple model of an image sensor. A reference image from memory is used for constructing a cost function and defining the optimal noise

Tao Yang

1998-01-01

336

Stochastic tipping points in climate dynamics  

NASA Astrophysics Data System (ADS)

A crucial question recently raised in climate dynamics concerns abrupt climate transitions: Are they due to a tipping point (TP) being exceeded, or is fast noisy dynamics the cause of their excitation? In this respect, a case study based on a low-order ocean model is developed to show that in an excitable dynamical system perturbed by noise (a possible climate condition) the TPs may have limited physical meaning, with the coherence resonance mechanism being predominant. The analysis is based on an operational definition of stochastic TP, which accounts for the effect of noise and reconciles formally the TP and coherence resonance views.

Pierini, Stefano

2012-02-01

337

Vestibular Labyrinth Contributions to Human Whole-Body Motion Discrimination  

PubMed Central

To assess the contributions of the vestibular system to whole-body motion discrimination in the dark, we measured direction-recognition thresholds as a function of frequency for yaw rotation, superior-inferior translation (“z-translation”), inter-aural translation (“y-translation”), and roll-tilt for 14 normal subjects and for three patients following total bilateral vestibular ablation. The patients had significantly higher average threshold measurements than normal (p<0.01) for yaw-rotation (depending upon frequency, 5.4× to 15.7× greater), z-translation (8.3× to 56.8× greater), y-translation (1.7× to 4.5× greater), and roll tilt (1.3× to 3.0× greater) – establishing the predominant contributions of the vestibular system for these motions in the dark.

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

2012-01-01

338

Vestibular labyrinth contributions to human whole-body motion discrimination.  

PubMed

To assess the contributions of the vestibular system to whole-body motion discrimination in the dark, we measured direction recognition thresholds as a function of frequency for yaw rotation, superior-inferior translation ("z-translation"), interaural translation ("y-translation"), and roll tilt for 14 normal subjects and for 3 patients following total bilateral vestibular ablation. The patients had significantly higher average threshold measurements than normal (p < 0.01) for yaw rotation (depending upon frequency, 5.4× to 15.7× greater), z-translation (8.3× to 56.8× greater), y-translation (1.7× to 4.5× greater), and roll tilt (1.3× to 3.0× greater)--establishing the predominant contributions of the vestibular system for these motions in the dark. PMID:23015443

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

2012-09-26

339

An electronic prosthesis mimicking the dynamic vestibular function  

NASA Astrophysics Data System (ADS)

This paper reports our progress toward development of a unilateral vestibular prosthesis. The sensing element of the prosthesis is a custom designed one-axis MEMS gyroscope. Similarly to the natural semicircular canal, the microscopic gyroscope senses angular motion of the head and generates voltages proportional to the corresponding angular accelerations. Then, voltages are sent to the pulse generating unit where angular motion is translated into voltage pulses. The voltage pulses are converted into current pulses and are delivered through specially designed electrodes, conditioned to stimulate the corresponding vestibular nerve branch. Our preliminary experimental evaluations of the prosthesis on a rate table indicate that the device's output matches the average firing rate of vestibular neurons to those in animal models reported in the literature. The proposed design is scalable; the sensing unit, pulse generator, and the current source can be potentially implemented on a single chip using integrated MEMS technology.

Shkel, Andrei M.

2006-04-01

340

Cervical Vestibular-Evoked Myogenic Potentials: Norms and Protocols  

PubMed Central

Vestibular-evoked myogenic potential (VEMP) testing is a vestibular function test used for evaluating saccular and inferior vestibular nerve function. Parameters of VEMP testing include VEMP threshold, latencies of p1 and n1, and p1-n1 interamplitude. Less commonly used parameters were p1-n1 interlatency, interaural difference of p1 and n1 latency, and interaural amplitude difference (IAD) ratio. This paper recommends using air-conducted 500?Hz tone burst auditory stimulation presented monoaurally via an inserted ear phone while the subject is turning his head to the contralateral side in the sitting position and recording the responses from the ipsilateral sternocleidomastoid muscle. Normative values of VEMP responses in 50 normal audiovestibular volunteers were presented. VEMP testing protocols and normative values in other literature were reviewed and compared. The study is beneficial to clinicians as a reference guide to set up VEMP testing and interpretation of the VEMP responses.

Isaradisaikul, Suwicha; Navacharoen, Niramon; Hanprasertpong, Charuk; Kangsanarak, Jaran

2012-01-01

341

Plasticity during Vestibular Compensation: The Role of Saccades  

PubMed Central

This paper is focused on one major aspect of compensation: the recent measures of saccadic responses to high acceleration head turns during human vestibular compensation and their possible implications for recovery after unilateral vestibular loss (UVL). New measurement techniques have provided additional insights into how patients recover after UVL and have given clues for vestibular rehabilitation. Prior to this it has not been possible to quantify the level of function of all the peripheral vestibular sense organs. Now it is. By using vestibular-evoked myogenic potentials to measure utricular and saccular function and by new video head impulse testing to measure semicircular canal function to natural values of head accelerations. With these new video procedures it is now possible to measure both slow phase eye velocity and also saccades during head movements with natural values of angular acceleration. The present evidence is that after UVL there is little or no restoration/compensation of slow phase eye velocity responses to natural head accelerations. It is doubtful as to whether the modest changes in slow phase eye velocity to small angular accelerations are functionally effective during compensation. On the other hand it is now clear that saccades can play a very important role in helping patients compensate and return to a normal lifestyle. Preliminary evidence suggests that different patterns of saccadic response may predict how well patients recover. Furthermore it may be possible to train patients to produce more effective saccadic patterns in the first days after their unilateral loss and possibly improve their compensation process. Some patients do learn new strategies, new behaviors, to conceal their inadequate vestibulo-ocular response but when those strategies are prevented from operating by using passive, unpredictable, high acceleration natural head movements, as in the head impulse test, the vestibular loss can be demonstrated. It is those very strategies which the tests exclude, which may be the cause of their successful compensation.

MacDougall, Hamish Gavin; Curthoys, Ian S.

2011-01-01

342

Neurohumoral reactions to long-term vestibular stimulation in man.  

PubMed

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

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

1993-02-01

343

The role of the superior vestibular nerve in generating ocular vestibular-evoked myogenic potentials to bone conducted vibration at Fz  

Microsoft Academic Search

ObjectiveThe n10 component (n10) of the ocular vestibular evoked myogenic potential (oVEMP) to brief bone conducted vibration (BCV) of the forehead at Fz is probably caused by the vibration selectively activating vestibular otolithic receptors. If the n10 is due primarily to utricular activation then diseases which affect only the superior division of the vestibular nerve (SVN) should reduce or eliminate

S. Iwasaki; Y. Chihara; Y. E. Smulders; A. M. Burgess; G. M. Halmagyi; I. S. Curthoys; T. Murofushi

2009-01-01

344

Influence of anxiety in spatial memory impairments related to the loss of vestibular function in rat.  

PubMed

It is now well established that vestibular information plays an important role in spatial memory processes. Although vestibular lesions induce anxiety in humans, this finding remains controversial in rodents. However, it is possible that anxiety-related behavior is associated with spatial memory impairments after vestibular lesions. We aimed to evaluate anxiety-like behavior and the effect of an anxiolytic treatment during a complex spatial memory task in a rat model of compensated bilateral vestibular lesions. Adult rats were divided into four groups, with or without vestibular lesions and, treated or untreated by diazepam. The vestibular lesion was performed by transtympanic injection of arsanilate and compared to transtympanic saline injection. Diazepam or saline was administered 1h before each test or learning session. Vestibular-lesioned rats exhibited anxiety-like behavior which was decreased with diazepam. Spatial memory performance was similar in control-treated and untreated groups, suggesting no effect on memory at the dose of diazepam used. Spatial memory performances were not modified by anxiolytic drug treatment in vestibular-lesioned rats compared to vestibular-lesioned rats without drug treatment. We conclude that bilateral vestibular lesions in rats induced anxiety-like behavior which was unrelated to spatial memory impairment and was probably specifically related to the loss of vestibular information. PMID:22633950

Machado, M L; Lelong-Boulouard, V; Smith, P F; Freret, T; Philoxene, B; Denise, P; Besnard, S

2012-05-24

345

Differentiating ascending vestibular pathways to the cortex involved in spatial cognition.  

PubMed

Vestibular information is an important factor in maintaining accurate spatial awareness. Yet, each of the cortical areas involved in processing vestibular information has unique functionality. Further, the anatomical pathways that provide vestibular input for cognitive processes are also distinct. This review outlines some of the current understanding of vestibular pathways contributing to the perception of self-motion in the cortex. The vestibulo-thalamic pathway is associated with self-motion cues for updating motor behaviors, spatial representations, and self versus object motion distinctions. The mammillo-tegmental pathway supplies vestibular input to create a cognitive representation of head direction. Self-motion and head direction information then converge to define self-location. By outlining the functional anatomy of the vestibular cortical pathways, a multi-sensory and multi-faceted view of vestibular related spatial awareness emerges. PMID:20555163

Shinder, Michael E; Taube, Jeffrey S

2010-01-01

346

Stochastic Differential Game Techniques.  

National Technical Information Service (NTIS)

This development of readily computable strategies for differential games with noise corrupted measurements was hampered by the so called closure problem of stochastic differential games. The solutions required either an infinite dimensional dynamic system...

B. Mons

1982-01-01

347

Stochastic Wear Processes.  

National Technical Information Service (NTIS)

A new class of non-decreasing stochastic processes is characterized. These processes satisfy a generalization of the notion of an increasing failure rate. From physical considerations, these processes seem suitable for describing the process of cumulative...

R. Morey

1965-01-01

348

VAWT Stochastic Wind Simulator.  

National Technical Information Service (NTIS)

A stochastic wind simulation for VAWTs (VSTOC) has been developed which yields turbulent wind-velocity fluctuations for rotationally sampled points. This allows three-component wind-velocity fluctuations to be simulated at specified nodal points on the wi...

J. H. Strickland

1987-01-01

349

Methodology for Stochastic Modeling.  

National Technical Information Service (NTIS)

The requirement to develop stochastic mathematical models arises across the whole range of engineering and applied research where observations are made of a physical process, corrupted by noise, and it is desired to determine the underlying nature, either...

H. E. Cohen

1985-01-01

350

Can Vestibular-Evoked Myogenic Potentials Help Differentiate M?ni?re Disease from Vestibular Migraine?  

PubMed Central

Objectives To characterize both cervical and ocular vestibular-evoked myogenic potential (cVEMP, oVEMP) responses to air-conducted sound (ACS) and midline taps in Ménière disease (MD), vestibular migraine (VM), and controls, as well as to determine if cVEMP or oVEMP responses can differentiate MD from VM. Study Design Prospective cohort study. Setting Tertiary referral center. Subjects and Methods Unilateral definite MD patients (n = 20), VM patients (n = 21) by modified Neuhauser criteria, and age-matched controls (n = 28). cVEMP testing used ACS (clicks), and oVEMP testing used ACS (clicks and 500-Hz tone bursts) and midline tap stimuli (reflex hammer and Mini-Shaker). Outcome parameters were cVEMP peak-to-peak amplitudes and oVEMP n10 amplitudes. Results Relative to controls, MD and VM groups both showed reduced click-evoked cVEMP (P < .001) and oVEMP (P < .001) amplitudes. Only the MD group showed reduction in tone-evoked amplitudes for oVEMP. Tone-evoked oVEMPs differentiated MD from controls (P = .001) and from VM (P = .007). The oVEMPs in response to the reflex hammer and Mini-Shaker midline taps showed no differences between groups (P > .210). Conclusions Using these techniques, VM and MD behaved similarly on most of the VEMP test battery. A link in their pathophysiology may be responsible for these responses. The data suggest a difference in 500-Hz tone burst–evoked oVEMP responses between MD and MV as a group. However, no VEMP test that was investigated segregated individuals with MD from those with VM.

Zuniga, M. Geraldine; Janky, Kristen L.; Schubert, Michael C.; Carey, John P.

2013-01-01

351

Stochastic Multivariate Evolution  

Microsoft Academic Search

\\u000a The discussions of stochastic methods in previous chapters were related to the consideration of a single random variable.\\u000a This approach is appropriate to explain the basic structure of evolution equations for stochastic processes and their PDFs.\\u000a On the other hand, most applications cannot be handled on the basis of methods that describe the evolution of single variables.\\u000a Real processes usually

Stefan Heinz

352

STOCHASTIC COOLING FOR RHIC  

Microsoft Academic Search

Emittance growth due to Intra-Beam Scattering significantly reduces the heavy ion luminosity lifetime in RHIC. Stochastic cooling of the stored beam could improve things considerably by counteracting IBS and preventing particles from escaping the rf bucket [1]. High frequency bunched-beam stochastic cooling is especially challenging but observations of Schottky signals in the 4-8 GHz band indicate that conditions are favorable

M. BRENNAN; J. M. CAMERON; P. WEI

2003-01-01

353

Should initial surveillance of vestibular schwannoma be abandoned?  

PubMed

Early diagnosis of vestibular schwannoma (VS) has increased in recent years because of increased longevity and availability of magnetic resonance imaging (MRI). Initial conservative radiological surveillance is often requested by patients and physicians to establish whether these tumors are growing before embarking on intervention. Initial observation of at least 1 year in all small VS was therefore recommended by some authors. We evaluated our prospective skull base database of VSs that were managed with initial radiological surveillance to establish when this policy should be abandoned and what predicts future growth. Fifty-four consecutive patients with VS in our institution who were managed by initial yearly MRI scanning were studied. The MRI data were collected prospectively and analyzed by Kodak CareStream viewing software where VS maximum diameters in three perpendicular planes and volume were calculated. One patient was excluded from the analysis as he had only one MRI follow-up. The median age of the 53 patients was 59 years (range, 26 to 86 years), 25 were males and 28 were females, and 33 were under 65 years of age; 18 VSs were extracanalicular, 18 were intracanalicular, and 17 extended both inside and outside the canal; 21 VSs were 1.2 cm(3) or less, 22 were 1.2 to 4 cm(3), and the rest were >4 cm(3). Using volumetric analysis, 29.72% of conservatively managed VS grew by at least 2 mm per year, and 70.82% did not grow in 5 years. Age, gender, symptoms, and side did not predict future growth. However, growth in the first year was a strong predictor of future growth (p?

Eljamel, Sarah; Hussain, Musheer; Eljamel, M Sam

2011-01-01

354

Vestibular and visual contribution to fish behavior under microgravity  

Microsoft Academic Search

Vestibular and visual information are two major factors fish use for controlling their posture under 1 G conditions. Parabolic flight experiments were carried out to observe the fish behavior under microgravity for several different strains of Medaka fish (Oryzias latipes). There existed a clear strain-difference in the behavioral response of the fish under microgravity: Some strains looped, while other strains

K. Ijiri

2000-01-01

355

Vestibular Stimulation and Development of the Small Premature Infant.  

ERIC Educational Resources Information Center

This study was designed to explore the effects of vestibular stimulation on the developmental behavior, respiratory functioning, weight and length gains, and morbidity and mortality rates of premature infants. A total of 20 infants participated in this study in 4 groups of 5 infants each. Group A infants were placed in a motorized hammock within…

Neal, Mary V.

356

Vestibular benefits to task savings in motor adaptation.  

PubMed

In everyday life, we seamlessly adapt our movements and consolidate them to multiple behavioral contexts. This natural flexibility seems to be contingent on the presence of movement-related sensorimotor cues and cannot be reproduced when static visual or haptic cues are given to signify different behavioral contexts. So far, only sensorimotor cues that dissociate the sensorimotor plans prior to force field exposure have been successful in learning two opposing perturbations. Here we show that vestibular cues, which are only available during the perturbation, improve the formation and recall of multiple control strategies. We exposed subjects to inertial forces by accelerating them laterally on a vestibular platform. The coupling between reaching movement (forward-backward) and acceleration direction (leftward-rightward) switched every 160 trials, resulting in two opposite force environments. When exposed for a second time to the same environment, with the opposite environment in between, subjects showed retention resulting in an ?3 times faster adaptation rate compared with the first exposure. Our results suggest that vestibular cues provide contextual information throughout the reach, which is used to facilitate independent learning and recall of multiple motor memories. Vestibular cues provide feedback about the underlying cause of reach errors, thereby disambiguating the various task environments and reducing interference of motor memories. PMID:23785131

Sarwary, A M E; Selen, L P J; Medendorp, W P

2013-06-19

357

The pattern of ciliary development in fetal mouse vestibular receptors  

Microsoft Academic Search

The development of vestibular receptors in the mouse was studied by scanning electron microscopy between the 13th gestation day to birth. On the 13th gestation day, the utricle was entirely covered with microvilli, which were often grouped around small kinocilia at the center of the macula. The vertical cristae were not clearly differentiated at this stage. On the 15th gestation

Joseph-Pascal Mbiene; Daniel Favre; Alain Sans

1984-01-01

358

Glycerol affects vestibular evoked myogenic potentials in Meniere's disease  

Microsoft Academic Search

Objectives: to show that abnormal vestibular evoked myogenic potentials on the sternocleidomastoid muscle (SCM) in patients with unilateral Meniere's disease are caused by endolymphatic hydrops. Subjects: six normal volunteers and 17 patients with unilateral Meniere's disease were examined. Methods: click-evoked myogenic potentials were recorded with surface electrodes over each SCM. Responses evoked by clicks recorded after oral administration of glycerol

Toshihisa Murofushi; Masaki Matsuzaki; Hideki Takegoshi

2001-01-01

359

Vestibular evoked myogenic potentials: optimal stimulation and clinical application  

Microsoft Academic Search

Summary  By easily stimulating the ear with loud sound and recording on tonically contracted neck muscles, vestibular evoked myogenic potential (VEMP) test can reflect inner ear function other than the cochlea and semicircular canal. This expands the test battery for clinicians to explore saccular disease, adding a potential usefulness to the sacculo-collic reflex. The ideal stimulation mode for VEMPs is as

Yi-Ho Young

2006-01-01

360

Vestibular evoked myogenic potential (VEMP) in patients with acoustic neuromas  

Microsoft Academic Search

Objective: To study the utility of VEMP (vestibular-evoked myogenic potential) in the diagnosis of acoustic neuromas.Methods: Eighteen patients with unilateral acoustic neuromas were subjected to this study. Myogenic potential responding to loud click stimuli was recorded at ipsilateral sternocleidomastoid muscle. A normal range of VEMP was obtained from 20 controls. VEMP responses were compared with both, clinical symptoms and results

Norihito Takeichi; Touru Sakamoto; Satoshi Fukuda; Yukio Inuyama

2001-01-01

361

The variance modulation associated with the vestibular evoked myogenic potential  

Microsoft Academic Search

ObjectiveModel considerations suggest that the sound-induced inhibition underlying the vestibular evoked myogenic potential (VEMP) briefly reduces the variance of the electromyogram (EMG) from which the VEMP is derived. Although more difficult to investigate, this inhibitory modulation of the variance promises to be a specific measure of the inhibition, in that respect being superior to the VEMP itself. This study aimed

Bernd Lütkenhöner; Claudia Rudack; Türker Basel

2011-01-01

362

Vestibular evoked myogenic potentials (VEMP) can detect asymptomatic saccular hydrops  

Microsoft Academic Search

Objective: The objective of this study was to explore the useful of vestibular evoked myogenic potential (VEMP) testing for detecting endolymphatic hydrops, especially in the second ear of patients with unilateral Meniere disease (MD). Methods: This study was performed at a tertiary care academic medical center. Part I consisted of postmortem temporal bone specimens from the temporal bone collection of

Ming-Yee Lin; Ferdinand C. A. Timmer; Brad S. Oriel; Guangwei Zhou; John J. Guinan; Sharon G. Kujawa; Barbara S. Herrmann; Saumil N. Merchant; Steven D. Rauch

2006-01-01

363

Postural control adaptation during galvanic vestibular and vibratory proprioceptive stimulation  

Microsoft Academic Search

The objective for this study was to investigate whether the adaptation of postural control was similar during galvanic vestibular stimulation and during vibratory proprioceptive stimulation of the calf muscles. Healthy subjects were tested during erect stance with eyes open or closed. An analysis method designed to consider the adaptive adjustments was used to evaluate the motion dynamics and the evoked

Per-Anders Fransson; Anna Hafström; Mikael Karlberg; Måns Magnusson; Annika Tjäder; Rolf Johansson

2003-01-01

364

Potential solutions to several vestibular challenges facing clinicians.  

PubMed

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

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

2010-01-01

365

[Vestibular schwannoma as cause of sudden unilateral deafness and tinnitus].  

PubMed

Vestibular schwannoma (VS) is a rare disorder. In Denmark, approximately 120 patients are being diagnosed yearly. This is a case report of a 29-year-old female patient with VS, which began with sudden deafness 6-7 years ago. The correct diagnosis was made relatively late. PMID:23153464

Stepanidis, Karén; Tving, Allan; Stangerup, Sven-Eric

2012-11-12

366

Tests of walking balance for screening vestibular disorders.  

PubMed

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

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

2012-01-01

367

Effects of betahistine on the vestibular receptors: binding sites  

Microsoft Academic Search

Betahistine has been used to treat several vestibular disorders of both central and peripheral origin. The objective of this work has been to study the betahistine action mechanism at the peripheral level. Experiments were carried out in wild larval axolotl (Ambystoma tigrinum). Multiunit extracellular recordings were obtained from the semicircular canal nerve using a suction electrode. Betahistine (10 µM to

Hortencia Chávez; Rosario Vega; Paolo Valli; Eugenio Mira; Claudio Benvenuti; S. Guth; Enrique Soto

2000-01-01

368

Stochastic beamforming for cochlear implant coding  

NASA Astrophysics Data System (ADS)

Cochlear implants are prosthetic devices used to provide hearing to people who would otherwise be profoundly deaf. The deliberate addition of noise to the electrode signals could increase the amount of information transmitted, but standard cochlear implants do not replicate the noise characteristic of normal hearing because if noise is added in an uncontrolled manner with a limited number of electrodes then it will almost certainly lead to worse performance. Only if partially independent stochastic activity can be achieved in each nerve fibre can mechanisms like suprathreshold stochastic resonance be effective. We are investigating the use of stochastic beamforming to achieve greater independence. The strategy involves presenting each electrode with a linear combination of independent Gaussian noise sources. Because the cochlea is filled with conductive salt solutions, the noise currents from the electrodes interact and the effective stimulus for each nerve fibre will therefore be a different weighted sum of the noise sources. To some extent therefore, the effective stimulus for a nerve fibre will be independent of the effective stimulus of neighbouring fibres. For a particular patient, the electrode position and the amount of current spread are fixed. The objective is therefore to find the linear combination of noise sources that leads to the greatest independence between nerve discharges. In this theoretical study we show that it is possible to get one independent point of excitation (one null) for each electrode and that stochastic beamforming can greatly decrease the correlation between the noise exciting different regions of the cochlea.

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

2007-06-01

369

Vestibular factors influencing the biomedical support of humans in space  

NASA Astrophysics Data System (ADS)

This paper will describe the biomedical support aspects of humans in space with respect to the vestibular system. The vestibular system is thought to be the primary sensory system involved in the short-term effects of space motion sickness although there is increasing evidence that many factors play a role in this complex set of symptoms. There is the possibility that an individual's inner sense of orientation may be strongly coupled with the susceptibility to space motion sickness. A variety of suggested countermeasures for space motion sickness will be described. Although there are no known ground-based tests that can predict space motion sickness, the search should go on. The long term effects of the vestibular system in weightlessness are still relatively unknown. Some preliminary data has shown that the otoconia are irregular in size and distribution following extended periods of weightlessness. The ramifications of this data are not yet known and because the data was obtained on lower order animals, definitive studies and results must wait until the space station era when higher primates can be studied for long durations. This leads us to artificial gravity, the last topic of this paper. The vestibular system is intimately tied to this question since it has been shown on Earth that exposure to a slow rotating room causes motion sickness for some period of time before adaptation occurs. If the artificial gravity is intermittent, will this mean that people will get sick every time they experience it? The data from many astronauts returning to Earth indicates that a variety of sensory illusions are present, especially immediately upon return to a 1- g environment. Oscillopsia or apparent motion of the visual surround upon head motion along with inappropriate eye motions for a given head motion, all indicate that there is much to be studied yet about the vestibular and CNS systems reaction to a sudden application of a steady state acceleration field like 1- g. From the above information it is obvious that the vestibular system does have unique requirements when it comes to the biomedical support of space flight. This is not to say that other areas such as cardiovascular, musculo-skeletal, immunological and hematological systems do not have their own unique requirements but that possible solutions to one system can provide continuing problems to another system. For example, artificial gravity might be helpful for long term stabilization of bone demineralization or cardiovascular deconditioning but might introduce a new set of problems in orientation, vestibular conflict and just plain body motion in a rotating space vehicle.

Lichtenberg, Byron K.

370

Stochastic effects in the planet migration and orbital distribution of the Kuiper Belt  

NASA Astrophysics Data System (ADS)

Assuming the Jovian planets experienced smooth orbital migrations, Malhotra successfully explained some important features of the Kuiper Belt by the mechanism of resonance capture. However, the migration should really be stochastic. In this paper we numerically simulate numerous orbital evolutions of test particles under such stochastic planet migrations. The main results are as follows. Given the proper parameters, the concentration of objects in the 3:2 resonance is distinct, while very few objects enter the 2:1 resonance, and consequently, the orbital distribution of Kuiper Belt objects matches the observational data very well. The stochastic effects excite the orbital eccentricities and inclinations of objects in the non-resonant regions. The introduction of stochastic effects also gives possible explanations of the mass depletion, and of the sources of the classical and scattered Kuiper Belt objects.

Zhou, Li-Yong; Sun, Yi-Sui; Zhou, Ji-Lin; Zheng, Jia-Qing; Valtonen, Mauri

2002-10-01

371

Representation of vestibular and visual cues to self-motion in ventral intraparietal (VIP) cortex  

PubMed Central

Convergence of vestibular and visual motion information is important for self-motion perception. One cortical area that combines vestibular and optic flow signals is the ventral intraparietal area (VIP). We characterized unisensory and multisensory responses of macaque VIP neurons to translations and rotations in three dimensions. Approximately half of VIP cells show significant directional selectivity in response to optic flow, half show tuning to vestibular stimuli, and one-third show multisensory responses. Visual and vestibular direction preferences of multisensory VIP neurons could be congruent or opposite. When visual and vestibular stimuli were combined, VIP responses could be dominated by either input, unlike medial superior temporal area (MSTd) where optic flow tuning typically dominates or the visual posterior sylvian area (VPS) where vestibular tuning dominates. Optic flow selectivity in VIP was weaker than in MSTd but stronger than in VPS. In contrast, vestibular tuning for translation was strongest in VPS, intermediate in VIP, and weakest in MSTd. To characterize response dynamics, direction-time data were fit with a spatiotemporal model in which temporal responses were modeled as weighted sums of velocity, acceleration, and position components. Vestibular responses in VIP reflected balanced contributions of velocity and acceleration, whereas visual responses were dominated by velocity. Timing of vestibular responses in VIP was significantly faster than in MSTd, whereas timing of optic flow responses did not differ significantly among areas. These findings suggest that VIP may be proximal to MSTd in terms of vestibular processing but hierarchically similar to MSTd in terms of optic flow processing.

Chen, Aihua; Deangelis, Gregory C.; Angelaki, Dora E.

2011-01-01

372

Signal detection theory and vestibular thresholds: I. Basic theory and practical considerations  

PubMed Central

Detection theory has been applied to the measurement of vestibular thresholds and vestibular sensory integration. Yet, a formal detection theory analysis of vestibular responses has not been published. Such a de novo analysis seems warranted because the vestibular system has characteristics that differ from other sensory systems, which impacts the application of detection theory. For example, the physical stimuli evoking vestibular responses are typically bidirectional (e.g., leftward/rightward); this bidirectional nature of vestibular responses leads to another characteristic—what is sometimes called vestibular bias—that must also be considered, since it can impact threshold measurements, including thresholds found using staircase procedures. This paper develops a basic model of vestibular noise and then analyzes this model for four standard paradigms—one-interval recognition, one-interval detection, two-interval detection, and two-interval recognition. While any of these paradigms might be justified for a specific application, it is concluded that one-interval recognition paradigms have advantages over other paradigms for many vestibular applications. One-interval recognition is favored over one-interval detection because it lends itself to a fixed detection boundary, is more efficient, and is less impacted by device vibration. One-interval recognition is generally favored over two-interval recognition because it assesses vestibular bias and can require substantially less time than two-interval tasks.

2011-01-01

373

Visual and vestibular contributions to pitch sway stabilization in the ankle muscles of normals and patients with bilateral peripheral vestibular deficits  

Microsoft Academic Search

Vestibular, visual, and proprioceptive influences on muscle activity correcting for backwards body tilt were investigated in normals and patients with bilateral peripheral vestibular deficits. Body tilt was induced by a dorsi-flexion rotation of the feet about the ankle joints while the subject stood on a force measuring platform. Ankle muscle activity and torque were monitored as upright stance was reestablished,

J. H. J. Allure; C. R. Pfaltz

1985-01-01

374

Enhanced stochastic oscillations in autocatalytic reactions  

NASA Astrophysics Data System (ADS)

We study a simplified scheme of k coupled autocatalytic reactions, previously introduced by Togashi and Kaneko. The role of stochastic fluctuations is elucidated through the use of the van Kampen system-size expansion and the results compared with direct stochastic simulations. Regular temporal oscillations are predicted to occur for the concentration of the various chemical constituents, with an enhanced amplitude resulting from a resonance which is induced by the intrinsic graininess of the system. The associated power spectra are determined and have a different form depending on the number of chemical constituents k . We make detailed comparisons in the two cases k=4 and k=8 . Agreement between the theoretical and numerical results for the power spectrum is good in both cases. The resulting spectrum is especially interesting in the k=8 system, since it has two peaks, which the system-size expansion is still able to reproduce accurately.

Dauxois, Thierry; di Patti, Francesca; Fanelli, Duccio; McKane, Alan J.

2009-03-01

375

Intrinsic noise induced resonance in presence of sub-threshold signal in Brusselator  

NASA Astrophysics Data System (ADS)

In a system of non-linear chemical reactions called the Brusselator, we show that intrinsic noise can be regulated to drive it to exhibit resonance in the presence of a sub-threshold signal. The phenomena of periodic stochastic resonance and aperiodic stochastic resonance, hitherto studied mostly with extrinsic noise, is demonstrated here to occur with inherent systemic noise using exact stochastic simulation algorithm due to Gillespie. The role of intrinsic noise in a couple of other phenomena is also discussed.

Dey, Supravat; Das, Dibyendu; Parmananda, P.

2011-09-01

376

Stochastic climate dynamics: Stochastic parametrizations and their global effects  

NASA Astrophysics Data System (ADS)

A well-known difficulty in modeling the atmosphere and oceans' general circulation is the limited, albeit increasing resolution possible in the numerical solution of the governing partial differential equations. While the mass, energy and momentum of an individual cloud, in the atmosphere, or convection chimney, in the oceans, is negligible, their combined effects over long times are not. Until recently, small, subgrid-scale processes were represented in general circulation models (GCMs) by deterministic "parametrizations." While A. Arakawa and associates had realized over three decades ago the conceptual need for ensembles of clouds in such parametrizations, it is only very recently that truly stochastic parametrizations have been introduced into GCMs and weather prediction models. These parametrizations essentially transform a deterministic autonomous system into a non-autonomous one, subject to random forcing. To study systematically the long-term effects of such a forcing has to rely on theory of random dynamical systems (RDS). This theory allows one to consider the detailed geometric structure of the random attractors associated with nonlinear, stochastically perturbed systems. These attractors extend the concept of strange attractors from autonomous dynamical systems to non-autonomous systems with random forcing. To illustrate the essence of the theory, its concepts and methods, we carry out a high-resolution numerical study of two "toy" models in their respective phase spaces. This study allows one to obtain a good approximation of their global random attractors, as well as of the time-dependent invariant measures supported by these attractors. The first of the two models studied herein is the Arnol'd family of circle maps in the presence of noise. The maps' fine-grained, resonant landscape --- associated with Arnol'd tongues --- is smoothed by the noise, thus permitting a comparison with the observable aspects of the "Devil's staircase" that arises in modeling the El Nino-Southern Oscillation (ENSO). These results are confirmed by studying a "French garden" that is obtained by smoothing a "Devil's quarry." Such a quarry results from coupling two circle maps, and random forcing leads to a smoothed version thereof. We thus suspect that stochastic parametrizations will stabilize the sensitive dependence on parameters that has been noticed in the development of GCMs. This talk represents joint work with Mickael D. Chekroun, D. Kondrashov, Eric Simonnet and I. Zaliapin. Several other talks and posters complement the results presented here and provide further insights into RDS theory and its application to the geosciences.

Ghil, Michael

2010-05-01

377

In vivo 13C magnetic resonance spectroscopy of human brain on a clinical 3 T scanner using [2-13C]glucose infusion and low-power stochastic decoupling.  

PubMed

This study presents the detection of [2-(13)C]glucose metabolism in the carboxylic/amide region in the human brain, and demonstrates that the cerebral metabolism of [2-(13)C]glucose can be studied in human subjects in the presence of severe hardware constraints of widely available 3 T clinical scanners and with low-power stochastic decoupling. In the carboxylic/amide region of human brain, the primary products of (13)C label incorporation from [2-(13)C]glucose into glutamate, glutamine, aspartate, gamma-aminobutyric acid, and N-acetylaspartate were detected. Unlike the commonly used alkanyl region where lipid signals spread over a broad frequency range, the carboxylic carbon signal of lipids was found to be confined to a narrow range centered at 172.5 ppm and present no spectral interference in the absence of lipid suppression. Comparison using phantoms shows that stochastic decoupling is far superior to the commonly used WALTZ sequence at very low decoupling power at 3 T. It was found that glutamine C1 and C5 can be decoupled using stochastic decoupling at 2.2 W, although glutamine protons span a frequency range of approximately 700 Hz. Detailed specific absorption rate analysis was also performed using finite difference time domain numerical simulation. PMID:19526500

Li, Shizhe; Zhang, Yan; Wang, Shumin; Yang, Jehoon; Ferraris Araneta, Maria; Farris, Amanda; Johnson, Christopher; Fox, Stephen; Innis, Robert; Shen, Jun

2009-09-01

378

STOCHASTIC COOLING FOR BUNCHED BEAMS.  

SciTech Connect

Problems associated with bunched beam stochastic cooling are reviewed. A longitudinal stochastic cooling system for RHIC is under construction and has been partially commissioned. The state of the system and future plans are discussed.

BLASKIEWICZ, M.

2005-05-16

379

Delay-aided stochastic multiresonances on scale-free FitzHugh-Nagumo neuronal networks  

NASA Astrophysics Data System (ADS)

The stochastic resonance in paced time-delayed scale-free FitzHugh-Nagumo (FHN) neuronal networks is investigated. We show that an intermediate intensity of additive noise is able to optimally assist the pacemaker in imposing its rhythm on the whole ensemble. Furthermore, we reveal that appropriately tuned delays can induce stochastic multiresonances, appearing at every integer multiple of the pacemaker's oscillation period. We conclude that fine-tuned delay lengths and locally acting pacemakers are vital for ensuring optimal conditions for stochastic resonance on complex neuronal networks.

Gan, Chun-Biao; Perc, Matjaz; Wang, Qing-Yun

2010-04-01

380

[The incidence of vestibular disorders among the patients suffering from otosclerosis].  

PubMed

The objective of the present study was to estimate the incidence of vestibular symptoms among the patients presenting with otosclerosis and their relationship with the form of this pathology. A total of 90 patients had the confirmed diagnosis of otosclerosis in the absence of concomitant diseases known to cause vestibular disorders. The patients were interviewed and underwent thorough examination. It turned out that 16.7% of them exhibited vestibular asymmetry; in other words, the frequency of this condition was higher than the incidence of vestibular disbalance in the general population. Most patients with vestibular symptoms and complaints were referred to the group with unilateral sensorineural hearing impairment that, however, can not be a marker of unilateral vestibular deficiency. PMID:23715484

Vartanian, M S; Banashek-Meshchiarkova, T V

2013-01-01

381

Structures and stochastic methods  

SciTech Connect

Studies and research on structures and stochastic methods in the soil dynamics and earthquake engineering filed are covered in this book. The first section is on structures and includes studies on bridges, loaded tanks, sliding structures and wood-framed houses. The second section covers dams, retaining walls and slopes. The third section on underground structures covers pipelines, water supply, fire loss, buried lifeline, and underground transmission lines. The final section is on stochastic methods and includes applications in earthquake response spectra, lifeline aqueduct systems, and various other areas.

Cakmak, A.S.

1987-01-01

382

Stochastic Hopfield neural networks  

NASA Astrophysics Data System (ADS)

Hopfield (1984 Proc. Natl Acad. Sci. USA 81 3088-92) showed that the time evolution of a symmetric neural network is a motion in state space that seeks out minima in the system energy (i.e. the limit set of the system). In practice, a neural network is often subject to environmental noise. It is therefore useful and interesting to find out whether the system still approaches some limit set under stochastic perturbation. In this paper, we will give a number of useful bounds for the noise intensity under which the stochastic neural network will approach its limit set.

Hu, Shigeng; Liao, Xiaoxin; Mao, Xuerong

2003-03-01

383

Stochastic optical active rheology  

NASA Astrophysics Data System (ADS)

We demonstrate a stochastic based method for performing active rheology using optical tweezers. By monitoring the displacement of an embedded particle in response to stochastic optical forces, a rapid estimate of the frequency dependent shear moduli of a sample is achieved in the range of 10-1-103 Hz. We utilize the method to probe linear viscoelastic properties of hydrogels at varied cross-linker concentrations. Combined with fluorescence imaging, our method demonstrates non-linear changes of bond strength between T cell receptors and an antigenic peptide due to force-induced cell activation.

Lee, Hyungsuk; Shin, Yongdae; Kim, Sun Taek; Reinherz, Ellis L.; Lang, Matthew J.

2012-07-01

384

Stochastic optical active rheology  

PubMed Central

We demonstrate a stochastic based method for performing active rheology using optical tweezers. By monitoring the displacement of an embedded particle in response to stochastic optical forces, a rapid estimate of the frequency dependent shear moduli of a sample is achieved in the range of 10?1–103?Hz. We utilize the method to probe linear viscoelastic properties of hydrogels at varied cross-linker concentrations. Combined with fluorescence imaging, our method demonstrates non-linear changes of bond strength between T cell receptors and an antigenic peptide due to force-induced cell activation.

Lee, Hyungsuk; Shin, Yongdae; Kim, Sun Taek; Reinherz, Ellis L.; Lang, Matthew J.

2012-01-01

385

Stochastic Models of Quasigeostrophic Turbulence  

Microsoft Academic Search

In this talk, I present a closure theory of quasigeostrophic turbulence for arbitrary shear flows based on stochastic models. A stochastic model represents the eddy-mean flow interaction through a nonnormal dynamical operator, and parameterizes the eddy-eddy interactions by an effective dissipation and random excitation. In the context of a stochastic model, the main facts which a closure theory of turbulence

T. Delsole

2005-01-01

386

Crossed effects on central vestibular neurons in the horizontal canal system of the frog  

Microsoft Academic Search

Summary  \\u000a1. \\u000aNeuronal discharges were recorded extracellularly in curarized frogs (Rana esculenta) with glassmicropipettes. Vestibular neurons, which were activated by ipsilateral horizontal angular acceleration and suppressed during deceleration (type 1) were found mainly in the medial part of the ventral vestibular nucleus.\\u000a2. \\u000aIn contrast to type 1 vestibular neuron of the cat, this type of neuron in the frog

S. Ozawa; W. Precht; H. Shimazu

1974-01-01

387

Frequency response of vestibular reflexes in neck, back, and lower limb muscles.  

PubMed

Vestibular pathways form short-latency disynaptic connections with neck motoneurons, whereas they form longer-latency disynaptic and polysynaptic connections with lower limb motoneurons. We quantified frequency responses of vestibular reflexes in neck, back, and lower limb muscles to explain between-muscle differences. Two hypotheses were evaluated: 1) that muscle-specific motor-unit properties influence the bandwidth of vestibular reflexes; and 2) that frequency responses of vestibular reflexes differ between neck, back, and lower limb muscles because of neural filtering. Subjects were exposed to electrical vestibular stimuli over bandwidths of 0-25 and 0-75 Hz while recording activity in sternocleidomastoid, splenius capitis, erector spinae, soleus, and medial gastrocnemius muscles. Coherence between stimulus and muscle activity revealed markedly larger vestibular reflex bandwidths in neck muscles (0-70 Hz) than back (0-15 Hz) or lower limb muscles (0-20 Hz). In addition, vestibular reflexes in back and lower limb muscles undergo low-pass filtering compared with neck-muscle responses, which span a broader dynamic range. These results suggest that the wider bandwidth of head-neck biomechanics requires a vestibular influence on neck-muscle activation across a larger dynamic range than lower limb muscles. A computational model of vestibular afferents and a motoneuron pool indicates that motor-unit properties are not primary contributors to the bandwidth filtering of vestibular reflexes in different muscles. Instead, our experimental findings suggest that pathway-dependent neural filtering, not captured in our model, contributes to these muscle-specific responses. Furthermore, gain-phase discontinuities in the neck-muscle vestibular reflexes provide evidence of destructive interaction between different reflex components, likely via indirect vestibular-motor pathways. PMID:23904494

Forbes, Patrick A; Dakin, Christopher J; Vardy, Alistair N; Happee, Riender; Siegmund, Gunter P; Schouten, Alfred C; Blouin, Jean-Sébastien

2013-07-31

388

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

SciTech Connect

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

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

1994-07-01

389

[Present situation and development of ocular vestibular-evoked myogenic potential].  

PubMed

Myogenic potentials evoked by air conducted sound (ACS), bone conducted vibration (BCV) or galvanic pulses can be recorded with surface electrodes over contracted muscles. These myogenic potentials are of vestibular origin (utricle and saccule) and so these potentials are called vestibular evoked myogenic potentials (VEMPs). Since the vestibular system has projections to many muscle systems, there are many such VEMPs. In this review, we discuss the generated origin, response pathway, waveform characteristics and clinical application of ocular vestibular-evoked myogenic potential (oVEMP). PMID:23833997

Hu, Juan; Xu, Min; Zhang, Qing

2013-04-01

390

Stochastic ontogenetic growth model  

Microsoft Academic Search

An ontogenetic growth model (OGM) for a thermodynamically closed system is generalized to satisfy both the first and second law of thermodynamics. The hypothesized stochastic ontogenetic growth model (SOGM) is shown to entail the interspecies allometry relation by explicitly averaging the basal metabolic rate and the total body mass over the steady-state probability density for the total body mass (TBM).

B. J. West

2012-01-01

391

Information and stochastic systems  

NASA Astrophysics Data System (ADS)

Equipment was purchased to support research in two main areas: communication channels with memory and signal detection and classification problems involving non-Gaussian stochastic processes. The research on communication channels involves largely the study of channel capacity under various assumptions and constraints. The research in signal detection and classification includes modeling, data analysis, and the development and evaluation of detection algorithms.

Baker, Charles R.

1987-11-01

392

Cortical influences on the vestibular nuclei of the cat  

Microsoft Academic Search

Our goal was to study potential substrates for cortical modulation of vestibular reflexes in the cat. In initial experiments,\\u000a injections of wheat-germ-agglutinate-horseradish-peroxidase into Deiters’ nucleus and the rostral descending nucleus revealed\\u000a bilateral colonies of retrogradely filled neurons in cortical areas 6, 2, and 3a (about 60 cells per colony). In cats anesthetized\\u000a with chloralose-urethane, we stimulated areas 2 and 3a

V. J. Wilson; P. Zarzecki; R. H. Schor; N. Isu; P. K. Rose; H. Sato; D. B. Thomson; T. Umezaki

1999-01-01

393

Vestibular evoked myogenic potentials in multiple sclerosis patients  

Microsoft Academic Search

Objectives: Vestibular evoked myogenic potentials (VEMPs) are saccular responses to loud acoustic stimuli and are recordable from the sterno-cleido-mastoid muscle ipsilaterally to the stimulated ear. This study aimed to investigate VEMPs in patients suffering from multiple sclerosis (MS), and to compare these findings with both clinical and instrumental data.Methods: We recorded VEMPs from 70 MS patients, whose clinical data were

Maurizio Versino; Silvia Colnaghi; Roberto Callieco; Roberto Bergamaschi; Alfredo Romani; Vittorio Cosi

2002-01-01

394

Development of Vestibular Evoked Myogenic Potentials in Preterm Neonates  

Microsoft Academic Search

Our recent study successfully recorded vestibular evoked myogenic potential (VEMP) responses in full-term newborns. However, when VEMP responses are elicited in preterm neonates remains unclear. This study employed the VEMP test in 27 low-risk preterm and 25 healthy full-term neonates without sedation to investigate the development of VEMP response after birth. Fourteen (26%) of 54 ears in preterm neonates exhibited

Shou-Jen Wang; Chun-Nan Chen; Wu-Shiun Hsieh; Yi-Ho Young

2008-01-01

395

Vestibular evoked myogenic potentials in Behcet’s disease  

Microsoft Academic Search

The aim of this study was to investigate vestibular evoked myogenic potentials (VEMPs) and their clinical significance in\\u000a Behcet’s disease. Twenty-six patients with Behcet’s disease and 25 healthy volunteers were evaluated for pure tone audiometry,\\u000a caloric response, and VEMPs. Sensorineural hearing loss was found in 53.8% of patients with Behcet’s disease, which was significantly\\u000a higher than controls. Four patients had

Seyra Erbek; Selim S. Erbek; Sema Yilmaz; Eftal Yucel; Levent N. Ozluoglu

2008-01-01

396

An analytical model of the vestibular evoked myogenic potential  

Microsoft Academic Search

The vestibular evoked myogenic potential (VEMP) can be modeled (scaling factors aside) as a convolution of the motor unit action potential (MUAP) of a representative motor unit, h(t), with the temporal modulation of the MUAP rate of all contributing motor units, r(t). Accordingly, the variance modulation associated with the VEMP can be modeled as a convolution of r(t) with the

Bernd Lütkenhöner; Türker Basel

2011-01-01

397

Vestibular Evoked Myogenic Potentials in Ipsilateral Delayed Endolymphatic Hydrops  

Microsoft Academic Search

We recorded vestibular evoked myogenic potentials (VEMPs) in 12 patients diagnosed as having ipsilateral delayed endolymphatic hydrops (DEH). Seventy-five percent (9\\/12) of the patients showed decreased or absent VEMPs in the affected ears. Almost all patients had normal VEMPs in the unaffected ears. In addition, in 4 patients, VEMPs were recorded before and 3 h after oral glycerol administration (1.3

Masafumi Ohki; Masaki Matsuzaki; Keiko Sugasawa; Toshihisa Murofushi

2002-01-01

398

Ocular vestibular evoked myogenic potentials are abnormal in internuclear ophthalmoplegia  

Microsoft Academic Search

ObjectiveThe cervical vestibular evoked myogenic potential (cVEMP) is sensitive to lower brainstem lesions affecting the vestibulo-collic pathway. We wished to determine whether the ocular VEMP (oVEMP), a recently-described otolith–ocular reflex, is also abnormal in patients with brainstem lesions. We tested patients with internuclear ophthalmoplegia (INO), caused by a brainstem lesion in the medial longitudinal fasciculus (MLF), to investigate whether the

S. M. Rosengren; J. G. Colebatch

2011-01-01

399

Asymmetry in vestibular responses to cross-coupled stimulus  

Microsoft Academic Search

Head turns performed while rotating about another axis result in a cross-coupled stimulus (CCS) to the vestibular system.\\u000a The CCS causes a tumbling sensation, and the magnitude of the tumbling sensation is dependent on the type of head turn (HT)\\u000a that is performed. Asymmetric CCS responses to different rotational directions are widely acknowledged, yet poorly understood.\\u000a The objective of this

Jaime Mateus; Jorge Cañizales; Andrew N. Hearn; Laurence R. Young

2011-01-01

400

Vestibular migraine: a critical review of treatment trials  

Microsoft Academic Search

Vestibular migraine (VM), also known as migraine-associated vertigo, is a common cause of dizziness in adults. We performed\\u000a a comprehensive literature search regarding treatment for VM or migraine-associated vertigo during the period of 1990–2008\\u000a and used, individually or in combination, the search terms VM, migraine-associated vertigo, migraine-associated dizziness,\\u000a migrainous vertigo, migraine and vertigo, migraine and disequilibrium, and headache and vertigo.

Majid Fotuhi; Braeme Glaun; Susan Y. Quan; Tzipora Sofare

2009-01-01

401

Afferent diversity and the organization of central vestibular pathways  

Microsoft Academic Search

This review considers whether the vestibular system includes separate populations of sensory axons innervating individual\\u000a organs and giving rise to distinct central pathways. There is a variability in the discharge properties of afferents supplying\\u000a each organ. Discharge regularity provides a marker for this diversity since fibers which differ in this way also differ in\\u000a many other properties. Postspike recovery of

Jay M. Goldberg

2000-01-01

402

Vestibular stimulation can relieve central pain of spinal origin  

Microsoft Academic Search

Study design:Single-blind, placebo-controlled case report.Setting:Center for Brain and Cognition, University of California, San Diego, CA, USA.Objective and results:We present the case of a 64-year-old woman with right-sided central pain following transverse myelitis of her cervical spinal cord in 2002. We investigated whether her pain could be improved beyond a placebo response by cold caloric vestibular stimulation. She had very little

P D McGeoch; V S Ramachandran

2008-01-01

403

Alignment of angular velocity sensors for a vestibular prosthesis  

PubMed Central

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

2012-01-01

404

Sleep deprivation effects on the vestibular habituation process  

Microsoft Academic Search

Studied the effects of sleep deprivation on habituation of the vestibular system in a stressful situation. 143 experienced pilots were exposed to 2 tests of Coriolis acceleration after periods of sleep deprivation (24-30 hrs) or rest (6 hrs). Nystagmus responses to Coriolis stimulation were recorded after 4 right-to-left tilts. Sleep deprivation resulted in (a) increased sensitivity to Coriolis stimulation, (b)

Patrick J. Dowd

1974-01-01

405

How Vestibular Neurons Solve the Tilt/Translation Ambiguity  

PubMed Central

The peripheral vestibular system is faced by a sensory ambiguity, where primary otolith afferents respond identically to translational (inertial) accelerations and changes in head orientation relative to gravity. Under certain conditions, this sensory ambiguity can be resolved using extra-otolith cues, including semicircular canal signals. Here we review and summarize how neurons in the vestibular nuclei, rostral fastigial nuclei, cerebellar nodulus/uvula, and thalamus respond during combinations of tilt and translation. We focus primarily on cerebellar cortex responses, as nodulus/uvula Purkinje cells reliably encode translation rather than net gravito-inertial acceleration. In contrast, neurons in the vestibular and rostral fastigial nuclei, as well as the ventral lateral and ventral posterior nuclei of the thalamus represent a continuum, with some encoding translation and some net gravito-inertial acceleration. This review also outlines how Purkinje cells use semicircular canal signals to solve the ambiguity problem and how this solution fails at low frequencies. We conclude by attempting to bridge the gap between the proposed roles of nodulus/uvula in tilt/translation discrimination and velocity storage.

Angelaki, Dora E.; Yakusheva, Tatyana A.

2010-01-01

406

[The visual-vestibular interaction in normal subjects].  

PubMed

Full-field optokinetic nystagmus (OKN) at constant speed of 40 degrees/s and 60 degrees/s, vestibular ocular reflex (VOR) (sinusoidal 0.2Hz, 60 degrees/s peak velocity) with different background (light and dark) and VOR-fix were observed in 72 normal subjects (144 normal eyes). The gain, FCV and DP of OKN, VVOR, VOR were also analysed. The gain of OKN is reduced accompanied with stimulation increasing, while the FCV is increased. The gain of VVOR is 1.08 +/- 0.09(mean +/- SD), while the gain of VOR is 0.64 +/- 0.09. The FCV of VOR is much reduced than that of VVOR. The FCV in the groups under 30 years of age are much faster than the groups above 30 years of age. The VOR-fix gain is 0.05 +/- 0.04. The DP of OKN, VVOR, and VOR are 0.05 +/- 0.04. The results showed an co-operation between visual and vestibular systems and the results also suggested that the series methods of visual-vestibular interaction (OKN, VVOR, VOR, VOR-fix) might be useful in eye movement examination. PMID:2289576

Gu, X; Wu, L; Wu, D Z

1990-12-01

407

[The visual-vestibular interaction in normal subjects].  

PubMed

Full-field optokinetic nystagmus (OKN) at constant speed of 40 0/s and 60 0/s, vestibular ocular reflex (VOR) (sinusoidal 0.2 Hz, 60 0/s peak velocity) with different background (light and dark) and VOR-fix were observed in 72 normal subjects (144 normal eyes). The gain, FCV and DP of OKN, VVOR, VOR were also analysed. The gain of OKN is reduced accompanied with stimulation increasing, while the FCV is increased. The gain of VVOR is 1.08 +/- 0.09 (X +/- SD), while the gain of VOR is 0.64 +/- 0.09. The FCV of VOR is much reduced than that of VVOR. The FCV in the groups under 30 years of age are much faster than the groups above 30 years of age. The VOR--fix gain is 0.05 +/- 0.04. The DP of OKN, VVOR, and VOR are 0.05 +/- 0.04. The results showed an co-operation between visual and vestibular systems and the results also suggested that the series methods of visual-vestibular interaction (OKN, VVOR, VOR, VOR-fix) might be useful in eye movement examination. PMID:2101368

Gu, X; Wu, L; Wu, D

1990-12-01

408

Galvanic vestibular stimulation modifies vection paths in healthy subjects.  

PubMed

The present study aimed at determining whether vestibular inputs contribute to the perception of the direction of self-motion. This question was approached by investigating the effects of binaural bipolar galvanic vestibular stimulation (GVS) on visually induced self-motion (i.e., vection) in healthy subjects. Stationary seated subjects were submitted to optokinetic stimulation inducing either forward or upward linear vection. While perceiving vection, they were administered trapezoidal GVS of different intensities and ramp durations. Subjects indicated the shape and direction of their perceived self-motion path throughout the experiment by a joystick, and after each trial by the manipulation of a 3D mannequin. Results show that: 1) GVS induced alterations of the path of vection; 2) these alterations occurred more often after GVS onset than after GVS offset; 3) the occurrence of vection path alterations after GVS onset depended on the intensity of GVS but not on the steepness of the GVS variation; 4) the vection path deviated laterally according to either an oblique or a curved path; and 5) the vection path deviated toward the cathode side after GVS onset. It is the first time that vestibular information, already known to contribute to the induction of vection, is shown to modify self-motion perception during the course of vection. PMID:16436483

Lepecq, Jean-Claude; De Waele, Catherine; Mertz-Josse, Sophie; Teyssèdre, Claudine; Huy, Patrice Tran Ba; Baudonnière, Pierre-Marie; Vidal, Pierre-Paul

2006-01-25

409

Vestibular evoked potentials in response to direct unilateral mechanical stimulation.  

PubMed

Evoked potentials produced by direct unilateral mechanical stimulation of the cannulated horizontal semicircular canal were investigated parametrically in anesthetized adult cats (40 mg/kg pentobarbital). Stimuli were fluid pressure pulses in a closed hydraulic system (no net flow), which was coupled to the lateral semicircular canal near the ampulla. Hydraulic waveform output and fluid pressure was monitored in situ via a parallel hydraulic circuit during experiments. Maximum fluid displacement at the level of the horizontal canal was 0.025 microliters. The intensity, duration, and presentation rate of the stimulus were varied during experiments. Field potentials were recorded differentially using subdermal electrodes, with the active lead in the region of the mastoid referenced to a distant nasal site. A total of 256 trials was accumulated for each run using an averaging computer. Evoked responses were physiologically vulnerable and reproducible, with little variance among animals. Response amplitude increased monotonically until saturation was noted and responses followed the temporal structure of the pressure wave. Polarity reversal with differing electrode placement suggests that the generator site lies within the mastoid. Further, intense broad-band acoustic stimuli and eighth nerve sectioning did not affect the vestibular evoked potentials, but could be shown to abolish the auditory evoked potentials. Results of these experiments support the notion that vestibular evoked potentials are related to the first derivative of the pressure pulse waveforms. Future experiments will be directed toward the assessment of vestibular physiology and pharmacology with this evoked response method. PMID:2496377

Coale, F S; Walsh, E J; McGee, J; Konrad, H R

1989-03-01

410

Effects of betahistine on vestibular receptors of the frog.  

PubMed

Betahistine is widely used in the symptomatic treatment of peripheral and central vestibular disorders. However, its remains unknown whether the drug can act directly on inner ear sensory organs. To this end, the effects of betahistine (10(-7)-10(-2) M) were examined on isolated preparations of frog semicircular canal mounted in a double-celled bath which allowed drug administration both in the endolymphatic and in the perilymphatic fluid. The effects of betahistine were evaluated by recording ampullar receptor potentials and nerve firing rate both at rest and during mechanical stimulation of the isolated preparation. The results demonstrated that endolymphatic administration of betahistine had no effect, whereas its perilymphatic administration could reduce greatly ampullar receptor resting discharge but had little effect on mechanically evoked responses. This observation may explain the anti-vertigo effects of betahistine. Vertigo is normally due to uncontrolled changes in vestibular receptor resting discharge. It is therefore probable that any factor able to reduce the resting firing rate of vestibular receptors and, in consequence, its variations, may have an anti-vertigo action. PMID:9726676

Botta, L; Mira, E; Valli, S; Perin, P; Zucca, G; Valli, P

1998-07-01

411

Stochastic phase synchronization in the crayfish mechanoreceptor/photoreceptor system  

NASA Astrophysics Data System (ADS)

The two light-sensitive neurons in the crayfish's abdominal sixth ganglion (``caudal photoreceptors,'' or CPRs), are both primary light sensors and secondary neurons in a mechanosensory pathway. Pei et al. (1996) demonstrated that light enhances the transduction of weak, periodic hydrodynamic stimuli (measured as an increase in the signal-to-noise ratio at the stimulus frequency in the power spectrum of the recorded neural spikes). This has been interpreted as a stochastic resonance effect, in which added light increases the noise intensity of the input to the photoreceptor (possibly through fluctuations in membrane potential), leading to an enhancement of the signal-to-noise ratio (SNR). Here, we discuss the recent demonstration (Bahar et al., 2002) of the correlation between a stochastic-resonance-like effect and an increase in stochastic phase synchronization between the neural response and a periodic mechanical stimulus. We also discuss a novel effect (Bahar et al., 2002) in which light increases the SNR of the second higher harmonic of a periodic input signal, effectively rectifying the input signal. This ``second harmonic effect'' can also be interpreted in terms of stochastic phase synchronization (Bahar et al., 2002). We review other recent results on the role of stochastic phase synchronization in mediating sensory responses in the crayfish nervous system.

Bahar, S.; Moss, F.

2003-03-01

412

Stochastic perturbations of the five-component Benard system  

NASA Astrophysics Data System (ADS)

The effect of added white noise on the dynamical system of a two-dimensional fluid layer heated from below with periodic free stress boundary conditions is investigated analytically. The exit integrations are estimated asymptotically, and the results are compared with those obtained by numerical integration in graphs. The stochastic resonance mechanism is discussed, and it is found that the effect of stochastic perturbations at large values of the aspect ratio (Gamma) is amplified by a factor proportional to Gamma squared. It is argued that such a mechanism could explain the experimental observations of Ahlers and Walden (1980) and Libchaber (1983).

Benzi, R.; Sutera, A.

1984-08-01

413

Recovery of Vestibular-Evoked Myogenic Potential: Relationship to Other Neural Disorders in Two Patients with Acute Sensorineural Hearing Loss  

Microsoft Academic Search

We report the recovery of the inferior vestibular neural system disorder by monitoring the vestibular-evoked myogenic potential (VEMP) in two patients suffering from acute sensorineural hearing loss with vertigo. Patients presented absent VEMP, canal paresis, and severe hearing disorder. After 10 months, the function of the inferior vestibular neural system was recovered in both cases while that of the superior

Kentaro Ochi; Toru Ohashi

2002-01-01

414

Convergence of vestibular and visual self-motion signals in an area of the posterior sylvian fissure  

PubMed Central

Convergence of visual motion information (optic flow) and vestibular signals is important for self-motion perception, and such convergence has been observed in the dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas. In contrast, the parieto-insular vestibular cortex (PIVC), a cortical vestibular area in the sylvian fissure, is not responsive to optic flow. Here we explore optic flow and vestibular convergence in the visual posterior sylvian area (VPS) of macaque monkeys. This area is located at the posterior end of the sylvian fissure, is strongly interconnected with PIVC, and receives projections from MSTd. We found robust optic flow and vestibular tuning in more than one-third of VPS cells, with all motion directions being represented uniformly. However, visual and vestibular direction preferences for translation were mostly opposite, unlike in area MSTd where roughly equal proportions of neurons have visual/vestibular heading preferences that are congruent or opposite. Overall, optic flow responses in VPS were weaker than those in MSTd, whereas vestibular responses were stronger in VPS than in MSTd. When visual and vestibular stimuli were presented together, VPS responses were dominated by vestibular signals, in contrast to MSTd, where optic flow tuning typically dominates. These findings suggest that VPS is proximal to MSTd in terms of vestibular processing, but distal to MSTd in terms of optic flow processing. Given the preponderance of neurons with opposite visual/vestibular heading preferences in VPS, this area may not play a major role in multisensory heading perception.

Chen, Aihua; DeAngelis, Gregory C.; Angelaki, Dora E.

2011-01-01

415

STOCHASTIC COOLING FOR RHIC.  

SciTech Connect

Emittance growth due to Intra-Beam Scattering significantly reduces the heavy ion luminosity lifetime in RHIC. Stochastic cooling of the stored beam could improve things considerably by counteracting IBS and preventing particles from escaping the rf bucket [1]. High frequency bunched-beam stochastic cooling is especially challenging but observations of Schottky signals in the 4-8 GHz band indicate that conditions are favorable in RHIC [2]. We report here on measurements of the longitudinal beam transfer function carried out with a pickup kicker pair on loan from FNAL TEVATRON. Results imply that for ions a coasting beam description is applicable and we outline some general features of a viable momentum cooling system for RHIC.

BLASKIEWICZ,M.BRENNAN,J.M.CAMERON,P.WEI,J.

2003-05-12

416

Stochastic stacking without filters  

SciTech Connect

The rate of accumulation of antiprotons is a critical factor in the design of p anti p colliders. A design of a system to accumulate higher anti p fluxes is presented here which is an alternative to the schemes used at the CERN AA and in the Fermilab Tevatron I design. Contrary to these stacking schemes, which use a system of notch filters to protect the dense core of antiprotons from the high power of the stack tail stochastic cooling, an eddy current shutter is used to protect the core in the region of the stack tail cooling kicker. Without filters one can have larger cooling bandwidths, better mixing for stochastic cooling, and easier operational criteria for the power amplifiers. In the case considered here a flux of 1.4 x 10/sup 8/ per sec is achieved with a 4 to 8 GHz bandwidth.

Johnson, R.P.; Marriner, J.

1982-12-01

417

Stochastic flights of propellers  

NASA Astrophysics Data System (ADS)

Kilometre-sized moonlets in Saturn's A ring create S-shaped wakes called 'propellers' in surrounding material. The Cassini spacecraft has tracked the motions of propellers for several years and finds that they deviate from Keplerian orbits with constant semimajor axes. The inferred orbital migration is known to switch sign. We show using a statistical test that the time series of orbital longitudes of the propeller Blériot is consistent with that of a time-integrated Gaussian random walk. That is, Blériot's observed migration pattern is consistent with being stochastic. We further show, using a combination of analytic estimates and collisional N-body simulations, that stochastic migration of the right magnitude to explain the Cassini observations can be driven by encounters with ring particles 10-20 m in radius. That the local ring mass is concentrated in decametre-sized particles is supported on independent grounds by occultation analyses.

Pan, Margaret; Rein, Hanno; Chiang, Eugene; Evans, Steven N.

2012-12-01

418

VAWT stochastic wind simulator  

SciTech Connect

A stochastic wind simulation for VAWTs (VSTOC) has been developed which yields turbulent wind-velocity fluctuations for rotationally sampled points. This allows three-component wind-velocity fluctuations to be simulated at specified nodal points on the wind-turbine rotor. A first-order convection scheme is used which accounts for the decrease in streamwise velocity as the flow passes through the wind-turbine rotor. The VSTOC simulation is independent of the particular analytical technique used to predict the aerodynamic and performance characteristics of the turbine. The VSTOC subroutine may be used simply as a subroutine in a particular VAWT prediction code or it may be used as a subroutine in an independent processor. The independent processor is used to interact with a version of the VAWT prediction code which is segmented into deterministic and stochastic modules. Using VSTOC in this fashion is very efficient with regard to decreasing computer time for the overall calculation process.

Strickland, J.H.

1987-04-01

419

STOCHASTIC COOLING POWER REQUIREMENTS.  

SciTech Connect

A practical obstacle for stochastic cooling in high-energy colliders like RHIC is the large amount of power needed for the cooling system. Based on the coasting-beam Fokker-Planck (F-P) equation, we analytically derived the optimum cooling rate and cooling power for a beam of uniform distribution and a cooling system of linear gain function. The results indicate that the usual back-of-envelope formula over-estimated the cooling power by a factor of the mixing factor M. On the other hand, the scaling laws derived from the coasting-beam Fokker-Planck approach agree with those derived from the bunched-beam Fokker-Planck approach if the peak beam intensity is used as the effective coasting-beam intensity. A longitudinal stochastic cooling system of 4-8 GHz bandwidth in RHIC can effectively counteract intrabeam scattering, preventing the beam from escaping the RF bucket becoming debunched around the ring.

WEI,J.BLASKIEWICZ,M.BRENNAN,M.

2004-07-05

420

About stochastization of motion of charged particles in geomagnetic field and in the field of a wave packet  

Microsoft Academic Search

The mechanism of stochastic acceleration of the particles in magnetic field and in the field of a wave packet in the conditions of geomagnetic trap is considered. A short survey of the latest works on the problem of stochastic heating of the particles and their resonance interaction with a wave packet in constant magnetic field is given. The simple conclusion

I. V. Amirkhanov; E. P. Zhidkov; V. V. Ignatov; A. N. Ilina; I. V. Ilin

1992-01-01

421

On Nonterminating Stochastic Games  

Microsoft Academic Search

A stochastic game is played in a sequence of steps; at each step the play is said to be in some state i, chosen from a finite collection of states. If the play is in state i, the first player chooses move k and the second player chooses move l, then the first player receives a reward akl<\\/sup>i<\\/sub>, and, with

A. J. Hoffman; R. M. Karp

1966-01-01

422

Disruption, Succession and Stochasticity  

Microsoft Academic Search

\\u000a Disruptions interfere with the orderly course of a process. Ecological disturbances, physical processes that remove living\\u000a biomass from an ecosystem, are common disruptions that are frequently observed in the marine benthos. Although often associated\\u000a with climatic or geological events, some disturbances arise from biological activity. Disturbances are often pulsed, stochastic\\u000a events at a local scale. At larger spatial and temporal

J. Timothy Wootton; Mathieu Cusson; Sergio Navarrete; Peter S. Petraitis

423

Entropy of stochastic flows  

SciTech Connect

For sets in a Hilbert space the concept of quadratic entropy is introduced. It is shown that this entropy is finite for the range of a stochastic flow of Brownian particles on R. This implies, in particular, the fact that the total time of the free travel in the Arratia flow of all particles that started from a bounded interval is finite. Bibliography: 10 titles.

Dorogovtsev, Andrei A [Institute of Mathematics of Ukrainian National Academy of Sciences, Kiev (Ukraine)

2010-06-29

424

VAWT stochastic wind simulator  

Microsoft Academic Search

A stochastic wind simulation for VAWTs (VSTOC) has been developed which yields turbulent wind-velocity fluctuations for rotationally sampled points. This allows three-component wind-velocity fluctuations to be simulated at specified nodal points on the wind-turbine rotor. A first-order convection scheme is used which accounts for the decrease in streamwise velocity as the flow passes through the wind-turbine rotor. The VSTOC simulation

Strickland

1987-01-01

425

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

PubMed

Autonomic manifestations of vestibular dysfunction and motion sickness are well established in the clinical literature. Recent studies of 'vestibular autonomic regulation' have focused predominantly on autonomic responses to stimulation of the vestibular sense organs in the inner ear. These studies have shown that autonomic responses to vestibular stimulation are regionally selective and have defined a 'vestibulosympathetic reflex' in animal experiments. Outside the realm of experimental preparations, however, the importance of vestibular inputs in autonomic regulation is unclear because controls for secondary factors, such as affective/emotional responses and cardiovascular responses elicited by muscle contraction and regional blood pooling, have been inadequate. Anatomic and physiologic evidence of an extensive convergence of vestibular and autonomic information in the brainstem suggests though that there may be an integrated representation of gravitoinertial acceleration from vestibular, somatic, and visceral receptors for somatic and visceral motor control. In the case of vestibular dysfunction or motion sickness, the unpleasant visceral manifestations (e.g. epigastric discomfort, nausea or vomiting) may contribute to conditioned situational avoidance and the development of agoraphobia. PMID:10097881

Balaban, C D

1999-02-01

426

Magnitude effects of galvanic vestibular stimulation on the trajectory of human gait  

Microsoft Academic Search

This study examines the contribution of the vestibular system during different magnitudes of galvanic vestibular stimulation (GVS) during human walking. Anodal threshold levels of GVS were determined for right and left sides for each subject. Seven conditions were tested (no stimulation, left and right anode stimulation) at one, two and three times threshold. GVS was delivered to the mastoid processes

Leah R Bent; Bradford J McFadyen; Veronique French Merkley; Paul M Kennedy; J. Timothy Inglis

2000-01-01

427

EMG responses in the soleus muscles evoked by unipolar galvanic vestibular stimulation  

Microsoft Academic Search

This study compared the effects of transmastoid galvanic stimulation with unilateral galvanic stimulation of vestibular afferents. We recorded the effects on soleus EMG occurring at short (SL) and medium (ML) latency, both in normal subjects and in patients with previous unilateral vestibular neurectomy. Unipolar cathodal and anodal stimulation on the same side produced opposite effects for both SL and ML

S. R. D Watson; J. G Colebatch

1997-01-01

428

Effects of Vestibular Rotatory Accelerations on Covert Attentional Orienting in Vision and Touch  

Microsoft Academic Search

Peripheral vestibular organs feed the central nervous system with inputs favoring the correct perception of space during head and body motion. Applying temporal order judgments (TOJs) to pairs of simultaneous or asynchronous stimuli presented in the left and right egocentric space, we evaluated the influence of leftward and rightward vestibular rotatory accelerations given around the vertical head-body axis on covert

Francesca Figliozzi; Paola Guariglia; Massimo Silvetti; Isabelle Siegler; Fabrizio Doricchi

2005-01-01

429

Gender differences in vestibular modulation of body mass in altered force environments  

Microsoft Academic Search

Body mass regulation is affected by the gravitational environment. Gravitational and linear acceleration information is transduced by the vestibular macular receptors. In addition, there are gender differences in the regulation of body mass and composition. This study therefore investigated the role of the vestibular system in the regulation of body mass in age-matched male and female rats. Four groups of

Charles Fuller; Patrick Fuller; Tana Hoban-Higgins

2008-01-01

430

Prenatal development of the vestibular ganglion and vestibulocerebellar fibres in the rat  

Microsoft Academic Search

We have used carbocyanine dye tracing techniques in conjunction with photoconversion and electronmicroscopy to examine the prenatal development of the central and peripheral processes of those vestibular ganglion cells projecting to the cerebellum. Developmental changes in the number of vestibular ganglion cells were assessed in paraffin-embedded material by nucleolar counting. In agreement with the results of parvalbumin staining, afferents to

K. W. S. Ashwell; Luan-ling Zhang

1998-01-01

431

Multisensory origin of the subjective first-person perspective: visual, tactile, and vestibular mechanisms.  

PubMed

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

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

2013-04-22

432

Vestibular-evoked myogenic potentials in two patients with Ramsay Hunt syndrome  

Microsoft Academic Search

We report on the function of the inferior vestibular nerve, as monitored by the vestibular-evoked myogenic potentials (VEMP), in two patients suffering from Ramsay Hunt syndrome. Both the patients presented canal paresis (CP) and hearing loss, but in one patient normal VEMP was recorded while the other presented vagus nerve paralysis plus no VEMP response at the highest stimulus intensity

Susumu Saito; Kentaro Ochi; Takehiko Kobayashi; Natsuki Sugiura; Yasushi Komatsuzaki; Toru Ohashi

2003-01-01

433

Could vestibular evoked myogenic potentials (VEMPs) also be useful in the diagnosis of perilymphatic fistula?  

Microsoft Academic Search

The role of vestibular evoked myogenic potentials (VEMPs) is at this time indisputable in the study of vestibular disorders. Furthermore, VEMPs are widely accepted as a diagnostic tool when a superior semicircular canal dehiscence (SCD) is suspected, presenting in such cases a lowering of threshold values able to raise a recordable response due to increased inner ear immittance. According to

Giovanni Carlo Modugno; Giorgio Magnani; Cristina Brandolini; Gabriella Savastio; Antonio Pirodda

2006-01-01

434

Ocular vestibular evoked myogenic potentials (OVEMPs) produced by impulsive transmastoid accelerations  

Microsoft Academic Search

ObjectiveRecent work has demonstrated the existence of ocular vestibular evoked myogenic potentials (OVEMPs), which likely reflect projections underlying the translational vestibular ocular reflex (TVOR). We examined extraocular muscle activity associated with impulsive acceleration of the head in the transmastoid plane.

Neil P. M. Todd; Sally M. Rosengren; James G. Colebatch

2008-01-01

435

Effect of gender on ocular vestibular-evoked myogenic potentials via various stimulation modes  

Microsoft Academic Search

ObjectiveThis study compared the characteristic parameters of ocular vestibular-evoked myogenic potentials (oVEMPs) via air-conducted sound (ACS), bone-conducted vibration (BCV), and galvanic vestibular stimulation (GVS) modes between male and female adults to determine whether gender affects oVEMPs.

Po-Hsien Sung; Po-Wen Cheng; Yi-Ho Young

2011-01-01

436

Acoustic, mechanical and galvanic stimulation modes elicit ocular vestibular-evoked myogenic potentials  

Microsoft Academic Search

ObjectiveThis study compared the characteristic parameters of ocular vestibular-evoked myogenic potentials (oVEMPs) elicited by the air-conducted sound (ACS) and bone-conducted vibration (BCV) stimulation modes as well as the galvanic vestibular stimulation (GVS) mode.

Po-Wen Cheng; Chien-Cheng Chen; Shou-Jen Wang; Yi-Ho Young

2009-01-01

437

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

Microsoft Academic Search

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

Güzin Akkuzu; Babur Akkuzu; Levent N. Ozluoglu

2006-01-01

438

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

ERIC Educational Resources Information Center

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

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

2011-01-01

439

Postural Control after Vestibular Schwannoma Resection Measured with Visual Feedback Posturography  

Microsoft Academic Search

Background: Vestibular symptoms after surgery diminish rapidly, but the simultaneous progress in active postural control has not been fully addressed. Objectives: The aim was to evaluate the progress in postural control in operated vestibular schwannoma (VS) patients with visual feedback posturography (VFP). Methods: 36 consecutive patients with unilateral VS were studied with the VFP pre-operatively, 1 month and 3 months

Meeli Hirvonen; Heikki Aalto; Timo P. Hirvonen

2005-01-01

440

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

PubMed Central

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

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

2013-01-01

441

Sympathetic Arousal to a Vestibular Stressor in High and Low Hostile Men  

ERIC Educational Resources Information Center

|The aim of the present experiment was to extend the literature on hostility and a cerebral systems based model of sympathetic arousal to a vestibular-based stress. Several authors have concluded that autonomic stress reactivity in high hostile individuals must be interpersonally based, whereas healthy vestibular system functioning does not depend…

Carmona, Joseph E.; Holland, Alissa K.; Stratton, Harrison J.; Harrison, David W.

2008-01-01

442

Responses to a Virtual Reality Grocery Store in Persons with and without Vestibular Dysfunction  

Microsoft Academic Search

People with vestibular dysfunction often complain of having difficulty walking in visually complex environments. Virtual reality may serve as a useful therapeutic tool for providing physical therapy to these people. The purpose of this pilot project was to explore the ability of people with and without vestibular dysfunction to use and tolerate virtual environments that can be used in physical

Susan L. Whitney; Patrick J. Sparto; Larry F. Hodges; Sabarish V. Babu; Joseph M. Furman; Mark S. Redfern

2006-01-01

443

The effects of response contingent vestibular stimulation on the behavior of autistic and retarded children  

Microsoft Academic Search

The purpose of the present experiment was to examine the reinforcing effects of repetitive vestibular stimulation. While both autistic and retarded children would push a button for vestibular stimulation, frequency of stimulation was an important parameter for autistics but not for retardates. These results were interpreted as evidence for central rather than peripheral locus of control of motility disturbances in

B. J. Freeman; Fred Frankel; E. R. Ritvo

1976-01-01

444

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

ERIC Educational Resources Information Center

|In order to better understand the role of the vestibular system in postural adjustments on unstable surfaces, we analyzed the effects of galvanic vestibular stimulation (GVS) on the pattern of muscle activity and joint displacements (ankle kne