The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Leon Glass - One of the best experts on this subject based on the ideXlab platform.
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Predicting Perception of the Wagon Wheel Illusion
Physical review letters, 2009Co-Authors: Patrick Martineau, Martin Aguilar, Leon GlassAbstract:Stroboscopic illumination of a rapidly rotating disk with radial spokes leads to a range of different stationary and moving images as the angular rotation frequency of the disk and the strobe frequency are varied. We compare predictions from the standard correlation model of motion perception with a model based on phase locking observed during Periodic Stimulation of an integrate-and-fire nonlinear oscillator. The close agreement between theoretical predictions and experimental observations suggests the possibility that Periodic forcing of nonlinear neural oscillations may play a role in motion perception.
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Dynamics of Parkinsonian tremor during deep brain Stimulation.
Chaos (Woodbury N.Y.), 2001Co-Authors: Michèle S. Titcombe, Leon Glass, Dominique Guehl, Anne BeuterAbstract:The mechanism by which chronic, high frequency, electrical deep brain Stimulation (HF-DBS) suppresses tremor in Parkinson’s disease is unknown. Rest tremor in subjects with Parkinson’s disease receiving HF-DBS was recorded continuously throughout switching the deep brain stimulator on (at an effective frequency) and off. These data suggest that the Stimulation induces a qualitative change in the dynamics, called a Hopf bifurcation, so that the stable oscillations are destabilized. We hypothesize that the Periodic Stimulation modifies a parameter affecting the oscillation in a time dependent way and thereby induces a Hopf bifurcation. We explore this hypothesis using a schematic network model of an oscillator interacting with Periodic Stimulation. The mechanism of time-dependent change of a control parameter in the model captures two aspects of the dynamics observed in the data: (1) a gradual increase in tremor amplitude when the Stimulation is switched off and a gradual decrease in tremor amplitude when the Stimulation is switched on and (2) a time delay in the onset and offset of the oscillations. This mechanism is consistent with these rest tremor transition data and with the idea that HF–DBS acts via the gradual change of a network property.
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Entrainment and annihilation of reentrant excitation in a Periodically stimulated ring of excitable media.
Methods of information in medicine, 1997Co-Authors: Taishin Nomura, Leon GlassAbstract:Excitable media, such as nerve, heart and the Belousov-Zhabotinsky reaction, exhibit a large excursion from equilibrium in response to a small but finite perturbation. Assuming a one-dimensional ring geometry of sufficient length, excitable media support a Periodic wave of circulation. As in the Periodic Stimulation of oscillations in ordinary differential equations, the effects of Periodic stimuli of the Periodically circulating wave can be described by a one-dimensional Poincare map. Depending on the period and intensity of the stimulus as well as its initial phase, either entrainment or termination of the original circulating wave is observed. These phenomena are directly related to clinical observations concerning Periodic Stimulation of a class of cardiac arrhythmias caused by reentrant wave propagation in the human heart.
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Entrainment and termination of reentrant wave propagation in a Periodically stimulated ring of excitable media.
Physical review. E Statistical physics plasmas fluids and related interdisciplinary topics, 1996Co-Authors: Taishin Nomura, Leon GlassAbstract:Excitable media, such as nerve, heart, and the Belousov-Zhabotinsky reaction, exhibit a large excursion from equilibrium in response to a small but finite perturbation. Assuming a one-dimensional ring geometry of sufficient length, excitable media support a Periodic wave of circulation. In analogy with earlier results found from the Periodic Stimulation of oscillations in ordinary differential equations, the effects of Periodic Stimulation of the Periodically circulating wave can be described by a one-dimensional map called the Poincar\'e map. Depending on the period and intensity of the Stimulation as well as its initial phase, either entrainment or termination of the original circulating wave is observed. These phenomena are directly related to clinical observations concerning Periodic Stimulation of a class of cardiac arrhythmias caused by reentrant wave propagation in the human heart. \textcopyright{} 1996 The American Physical Society.
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Evolution of rhythms during Periodic Stimulation of embryonic chick heart cell aggregates.
Circulation research, 1991Co-Authors: Wanzhen Zeng, Leon Glass, Alvin ShrierAbstract:During Periodic Stimulation of spontaneously beating chick heart cell aggregates, there is often an evolution of coupling patterns between the stimulator and the aggregate action potential. For example, at rapid Stimulation frequencies, a rhythm that is initially 1:1 (stimulus frequency:aggregate frequency) can evolve to other rhythms such as 5:4 and 4:3. Time-dependent effects generated during Periodic Stimulation are characterized by three types of experiments to determine 1) the effect of Periodic Stimulation on the intrinsic cardiac beat rate (overdrive suppression), 2) the effect of Periodic Stimulation on the phase resetting properties of the aggregate, and 3) the time-dependent changes in the coupling patterns between the stimulator and the aggregate during Periodic Stimulation. The protocols involved variations in the duration and rate of Periodic Stimulation. A mathematical model is developed in the form of a two-dimensional finite difference equation based on the data from experiments 1 and 2. The model is used to predict the data generated by experiment 3. There is good correspondence with the experiments in that the theory reproduces complex transitions between various rhythms and displays irregular rhythms similar to those observed experimentally. These results have implications for the evolution of cardiac arrhythmias such as atrioventricular heart block and modulated parasystole.
Flavio Frohlich - One of the best experts on this subject based on the ideXlab platform.
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Stochastic resonance mediates the state-dependent effect of Periodic Stimulation on cortical alpha oscillations
eLife, 2017Co-Authors: Jeremie Lefebvre, Axel Hutt, Flavio FrohlichAbstract:Brain Stimulation can be used to engage and modulate rhythmic activity in brain networks. However, the outcomes of brain Stimulation are shaped by behavioral states and endogenous fluctuations in brain activity. To better understand how this intrinsic oscillatory activity controls the susceptibility of the brain to Stimulation, we analyzed a computational model of the thalamo-cortical system in two distinct states (rest and task-engaged) to identify the mechanisms by which endogenous alpha oscillations (8Hz-12Hz) are modulated by Periodic Stimulation. Our analysis shows that the different responses to Stimulation observed experimentally in these brain states can be explained by a passage through a bifurcation combined with stochastic resonance - a mechanism by which irregular fluctuations amplify the response of a nonlinear system to weak Periodic signals. Indeed, our findings suggest that modulation of brain oscillations is best achieved in states of low endogenous rhythmic activity, and that irregular state-dependent fluctuations in thalamic inputs shape the susceptibility of cortical population to Periodic Stimulation.
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stochastic resonance mediates the state dependent effect of Periodic Stimulation on cortical alpha oscillations
bioRxiv, 2017Co-Authors: Jeremie Lefebvre, Axel Hutt, Flavio FrohlichAbstract:ABSTRACT Brain Stimulation can be used to engage and modulate rhythmic activity in cortical networks. However, the outcomes have been shown to be impacted by behavioral states and endogenous brain fluctuations. To better understand how this intrinsic oscillatory activity controls the brain’s susceptibility to Stimulation, we analyzed a computational model of the thalamocortical system in both the rest and task states, to identify the mechanisms by which endogenous alpha oscillations (8Hz-12Hz) are impacted by Periodic Stimulation. Our analysis shows that the differences between different brain states can be explained by a passage through a bifurcation combined to stochastic resonance - a mechanism whereby irregular fluctuations amplify the response of a nonlinear system to weak signals. Indeed, our findings suggest that modulating brain oscillations is best achieved in states of low endogenous rhythmic activity, and that irregular state-dependent fluctuations in thalamic inputs shape the susceptibility of cortical population to Periodic Stimulation.
Jacques Demongeot - One of the best experts on this subject based on the ideXlab platform.
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Entrainment of the Respiratory Rhythm: A New Approach
Journal of theoretical biology, 1993Co-Authors: P.f. Baconnier, Gila Benchetrit, P. Pachot, Jacques DemongeotAbstract:When we Periodically perturbed the central respiratory oscillator with a controlled Periodic Stimulation provided by a mechanical ventilator, an entrainment phenomenon occurred: the actual rhythm of the respiratory centres was phase locked to the Periodic Stimulation. In some experiments, we observed an intermittence phenomenon: the respiratory rhythm successively seemed entrained, departed from this mode for few cycles, returned to the previous pseudo entrainment and so on. From intermittence data, we were able to plot a phase response curve. From literature data on the effects of a single Stimulation applied at various moments in the respiratory cycle, we built up a mathematical model designed to simulate entrainment experiments. This model simulated entrainment phenomenon, but did not satisfactorily accommodate the experimental phase response curve. The section of the simulated phase response curve responsible for discrepancies was the result of the combination of an inspiratory shortening owing to a Stimulation occurring during inspiration, and a positive relationship between inspiratory duration TI and expiratory duration TE. We changed the TE-TI relationship, assuming that the expiratory duration is determined not by the inspiratory duration but rather by the lung volume at the end of inspiration. The revised model was then able to exhibit almost all the qualitative properties previously noted in experiments. The significance in biological terms of the new TE-TI relationship, which is apparently incompatible with almost all previous experimental data, is discussed.
Jeremie Lefebvre - One of the best experts on this subject based on the ideXlab platform.
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Stochastic resonance mediates the state-dependent effect of Periodic Stimulation on cortical alpha oscillations
eLife, 2017Co-Authors: Jeremie Lefebvre, Axel Hutt, Flavio FrohlichAbstract:Brain Stimulation can be used to engage and modulate rhythmic activity in brain networks. However, the outcomes of brain Stimulation are shaped by behavioral states and endogenous fluctuations in brain activity. To better understand how this intrinsic oscillatory activity controls the susceptibility of the brain to Stimulation, we analyzed a computational model of the thalamo-cortical system in two distinct states (rest and task-engaged) to identify the mechanisms by which endogenous alpha oscillations (8Hz-12Hz) are modulated by Periodic Stimulation. Our analysis shows that the different responses to Stimulation observed experimentally in these brain states can be explained by a passage through a bifurcation combined with stochastic resonance - a mechanism by which irregular fluctuations amplify the response of a nonlinear system to weak Periodic signals. Indeed, our findings suggest that modulation of brain oscillations is best achieved in states of low endogenous rhythmic activity, and that irregular state-dependent fluctuations in thalamic inputs shape the susceptibility of cortical population to Periodic Stimulation.
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stochastic resonance mediates the state dependent effect of Periodic Stimulation on cortical alpha oscillations
bioRxiv, 2017Co-Authors: Jeremie Lefebvre, Axel Hutt, Flavio FrohlichAbstract:ABSTRACT Brain Stimulation can be used to engage and modulate rhythmic activity in cortical networks. However, the outcomes have been shown to be impacted by behavioral states and endogenous brain fluctuations. To better understand how this intrinsic oscillatory activity controls the brain’s susceptibility to Stimulation, we analyzed a computational model of the thalamocortical system in both the rest and task states, to identify the mechanisms by which endogenous alpha oscillations (8Hz-12Hz) are impacted by Periodic Stimulation. Our analysis shows that the differences between different brain states can be explained by a passage through a bifurcation combined to stochastic resonance - a mechanism whereby irregular fluctuations amplify the response of a nonlinear system to weak signals. Indeed, our findings suggest that modulating brain oscillations is best achieved in states of low endogenous rhythmic activity, and that irregular state-dependent fluctuations in thalamic inputs shape the susceptibility of cortical population to Periodic Stimulation.
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Shaping Intrinsic Neural Oscillations with Periodic Stimulation.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2016Co-Authors: Christoph Herrmann, Axel Hutt, Micah M. Murray, Silvio Ionta, Jeremie LefebvreAbstract:Rhythmic brain activity plays an important role in neural processing and behavior. Features of these oscillations, including amplitude, phase, and spectrum, can be influenced by internal states (e.g., shifts in arousal, attention or cognitive ability) or external Stimulation. Electromagnetic Stimulation techniques such as transcranial magnetic Stimulation, transcranial direct current Stimulation, and transcranial alternating current Stimulation are used increasingly in both research and clinical settings. Currently, the mechanisms whereby time-dependent external stimuli influence population-scale oscillations remain poorly understood. Here, we provide computational insights regarding the mapping between Periodic pulsatile Stimulation parameters such as amplitude and frequency and the response dynamics of recurrent, nonlinear spiking neural networks. Using a cortical model built of excitatory and inhibitory neurons, we explored a wide range of Stimulation intensities and frequencies systematically. Our results suggest that rhythmic Stimulation can form the basis of a control paradigm in which one can manipulate the intrinsic oscillatory properties of driven networks via a plurality of input-driven mechanisms. Our results show that, in addition to resonance and entrainment, nonlinear acceleration is involved in shaping the rhythmic response of our modeled network. Such nonlinear acceleration of spontaneous and synchronous oscillatory activity in a neural network occurs in regimes of intense, high-frequency rhythmic Stimulation. These results open new perspectives on the manipulation of synchronous neural activity for basic and clinical research. SIGNIFICANCE STATEMENT Oscillatory activity is widely recognized as a core mechanism for information transmission within and between brain circuits. Noninvasive Stimulation methods can shape this activity, something that is increasingly capitalized upon in basic research and clinical practice. Here, we provide computational insights on the mechanistic bases for such effects. Our results show that rhythmic Stimulation forms the basis of a control paradigm in which one can manipulate the intrinsic oscillatory properties of driven networks via a plurality of input-driven mechanisms. In addition to resonance and entrainment, nonlinear acceleration is involved in shaping the rhythmic response of our modeled network, particularly in regimes of high-frequency rhythmic Stimulation. These results open new perspectives on the manipulation of synchronous neural activity for basic and clinical research.
P.f. Baconnier - One of the best experts on this subject based on the ideXlab platform.
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Entrainment of the Respiratory Rhythm: A New Approach
Journal of theoretical biology, 1993Co-Authors: P.f. Baconnier, Gila Benchetrit, P. Pachot, Jacques DemongeotAbstract:When we Periodically perturbed the central respiratory oscillator with a controlled Periodic Stimulation provided by a mechanical ventilator, an entrainment phenomenon occurred: the actual rhythm of the respiratory centres was phase locked to the Periodic Stimulation. In some experiments, we observed an intermittence phenomenon: the respiratory rhythm successively seemed entrained, departed from this mode for few cycles, returned to the previous pseudo entrainment and so on. From intermittence data, we were able to plot a phase response curve. From literature data on the effects of a single Stimulation applied at various moments in the respiratory cycle, we built up a mathematical model designed to simulate entrainment experiments. This model simulated entrainment phenomenon, but did not satisfactorily accommodate the experimental phase response curve. The section of the simulated phase response curve responsible for discrepancies was the result of the combination of an inspiratory shortening owing to a Stimulation occurring during inspiration, and a positive relationship between inspiratory duration TI and expiratory duration TE. We changed the TE-TI relationship, assuming that the expiratory duration is determined not by the inspiratory duration but rather by the lung volume at the end of inspiration. The revised model was then able to exhibit almost all the qualitative properties previously noted in experiments. The significance in biological terms of the new TE-TI relationship, which is apparently incompatible with almost all previous experimental data, is discussed.