Frequency Entrainment Research Articles

A combined EEG-fMRI investigation of ?rhythmic? versus ?vigilant? processing I: neural dynamics

Event Abstract Back to Event A combined EEG-fMRI investigation of “rhythmic” versus “vigilant” processing I: neural dynamics Gabriella Musacchia1*, Nienke Van Atteveldt2, 3, Pejman Sehatpour1, Elana Zion-Golumbic3, Peter Lakatos1, Pablo A. Gaspar3, Charles E. Schroeder3 and Dan Javitt3 1 Nathan S. Kline Institute for Psychiatric Research, United States 2 Maastricht University, Netherlands 3 Nathan S. Kline Institute for Psychiatric Research, Columbia University, United States Prior findings show that low frequency oscillatory entrainment to an attended rhythmic stream facilitates processing by aligning high-excitability oscillation phases to the events in the stream, but with attention to random events, low frequency activity is suppressed, while high frequency (gamma) activity is enhanced. We test the hypothesis that auditory processing switches between “random” (continuous gamma) and “rhythmic” (low frequency entrainment) modes depending on the rhythmicity of attended stimuli. We recorded simultaneous fMRI and EEG during perfectly regular and random (jittered) tone sequences while subjects performed an oddball task. We characterized faster dynamics by analyzing EEG activity in low and high frequency bands. We examined networks and slow dynamics using fMRI (van Atteveldt et al., accompanying abstract). We also correlated EEG power fluctuations in different bands with fMRI time-courses. Subjects were faster at detecting oddball targets during rhythmic blocks. Attended rhythmic stimuli elicited enhanced low frequency power (~1-2 Hz) including the band corresponding to entrainment at the rate of stimulation. Attended random stimuli induced higher power in the gamma band, indicating more continuous excitability. Combined EEG-fMRI analysis in the driving frequency showed correlations in a widespread cortical network, including auditory, motor and superior temporal cortices whereas correlations of high frequency power and fMRI activity was concentrated in auditory cortex. These results support the idea that distinct neural dynamics and brain regions are involved during rhythmic vs. random processing, with the former engaged during perception of predictable patterns, and the latter dominant in situations where the sound timing is unpredictable. Funding: Supported by R37MH049334. Keywords: EEG, fMRI, Perception Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Neurophysiology of Sensation and Perception Citation: Musacchia G, Van Atteveldt N, Sehatpour P, Zion-Golumbic E, Lakatos P, Gaspar PA, Schroeder CE and Javitt D (2011). A combined EEG-fMRI investigation of “rhythmic” versus “vigilant” processing I: neural dynamics. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00342 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Gabriella Musacchia, Nathan S. Kline Institute for Psychiatric Research, New York, United States, gmusacchia@pacific.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Gabriella Musacchia Nienke Van Atteveldt Pejman Sehatpour Elana Zion-Golumbic Peter Lakatos Pablo A Gaspar Charles E Schroeder Dan Javitt Google Gabriella Musacchia Nienke Van Atteveldt Pejman Sehatpour Elana Zion-Golumbic Peter Lakatos Pablo A Gaspar Charles E Schroeder Dan Javitt Google Scholar Gabriella Musacchia Nienke Van Atteveldt Pejman Sehatpour Elana Zion-Golumbic Peter Lakatos Pablo A Gaspar Charles E Schroeder Dan Javitt PubMed Gabriella Musacchia Nienke Van Atteveldt Pejman Sehatpour Elana Zion-Golumbic Peter Lakatos Pablo A Gaspar Charles E Schroeder Dan Javitt Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Dynamics of an excitable glow-discharge plasma under external forcing

Glow discharge plasma in the excitable regime shows rich dynamical behavior under external forcing. By perturbing the plasma with a subthreshold sawtooth periodic signal, we obtained small subthreshold oscillations that showed resonance with the perturbation frequency. The resonance phenomenon can be useful to estimate characteristic of an excitable system. However, for suprathreshold perturbation, frequency entrainment was observed. In this case, the system showed harmonic frequency entrainment for the perturbation frequencies greater than the characteristic frequency of the system and the excitable behavior for the perturbation frequencies well below the characteristic frequency. The experiments were performed in a glow-discharge plasma where excitability was achieved at a suitable discharge voltage and gas pressure.

Analysis of Spatio-temporal Pattern Formation in a PEM Fuel Cell with Pt ∕ Ru Anode Exposed to H2 ∕ CO Mixtures

In 2005 Zhang and Datta published a model for describing autonomous potential oscillations in a -catalyst-polymer electrolyte membrane (PEM) fuel cell operated with CO rich reformate [ J. X. Zhang and R. Datta , J. Electrochem. Soc. , 152 , A1180 (2005) ]. In the present contribution, we simplify a spatially extended version of this model in order to relate appearing pattern formation to electrochemical coupling mechanisms described by Krischer [ K. Krischer , in Advances in Electrochemical Science and Engineering, Wiley (2003) ]. It is concluded that mean-field- and migration-coupling are the fundamental mechanisms dictating pattern formation in the studied system. By artificially separating the electrical coupling terms it is found that large mean-field-coupling leads to a frequency entrainment and migration-coupling to a spatio-temporal intermittency scenario. It is argued that each of the situations can be found under realistic conditions, depending on the membrane conductivity and the system dimensions.

Bond Graph Modeling of an Internally Damped Nonideal Flexible Spinning Shaft

The rotating internal damping or nonconservative circulatory force in a rotor shaft system causes instability beyond a certain threshold rotor spinning speed. However, if the source loading of the drive is considered, then the rotor spin is entrained at the stability threshold and a stable whirl orbit is observed about the unstable equilibrium. As we move toward the use of more and more lightweight rotor dynamic components such as the shaft and the motor, overlooking this frequency entrainment phenomenon while sizing the actuator in the design stage may lead to undesirable performance. This applies to many emerging areas of strategic importance such as in vivo medical robots where flexible probes are used and space robotics applications involving rotating tools. We analyze this spin entrainment phenomenon in a distributed parameter model of a spinning shaft, which is driven by a nonideal dc motor. A drive whose dynamics is influenced by the dynamics of the driven system is called a nonideal source and the whole system is referred to as a nonideal system. In particular, we show the advantages of representing such nonideal drive-system interactions in a modular manner through bond graph modeling as compared to standard equation models where the energetic couplings between dynamic variables are not explicitly shown. The developed modular bond graph model can be extended to include rotor disks and bearings placed at different locations on the shaft. Moreover, the power conserving property of the junction structure of the bond graph model is exploited to derive the source loading expressions, which are then used to analytically derive the steady-state spinning frequency and whirl orbit amplitude as functions of the drive and the rotor system parameters. We show that the higher transverse modes may become unstable before the lower ones under certain parametric conditions. The shaft spinning speed is entrained at the lowest stability threshold among all transverse modes. The bond graph model is used for numerical simulation of the system to validate the steady-state results obtained from the theoretical study.

Initiating inspiration outside the medulla does produce eupneic breathing

ARTERIAL PCO2 IS DICTATED by the ratio between the level of pulmonary gas exchange and alveolar ventilation (VA), not minute ventilation. If so, how could isocapnia be maintained if only the magnitude (tidal volume, VT) and duration (TI and TTOT) of the neural output produced by the central pattern generator of breathing (CPG) can be altered? In other words, what is the strategy used by the respiratory control system to match its output to the level of pulmonary gas exchange to keep arterial blood gas homeostasis if this neural output con- tributes to dead space ventilation? In this Viewpoint, we will show that when the spontaneous breathing is replaced by a cortically triggered breathing pattern at various breathing frequencies (we will name this new rhythm an "ecto-rhythm"), the relationship between TTOT and VT has a positive intercept that averages the pulmonary dead space. As a result, the coupling between ventilation and the pulmonary gas exchange becomes possible (17). We will present the idea that whenever isocapnia is maintained during spontaneous or automatic breathing, the magnitude and dura- tion of breath cycles must display the same relationship as during an ecto-rhythm (15). Conversely, we will discuss the implications of the observation that breathing can display the same essential regulatory properties whether generated outside or within the pontomedullary CPG area (7). Ecto-rhythm, breathing pattern, and gas exchange: the re-

Synchronization of oscillators with long-range power law interactions

We present analytical calculations and numerical simulations for the synchronization of oscillators interacting via a long-range power law interaction on a one-dimensional lattice. We have identified the critical value of the power law exponent α(c) across which a transition from a synchronized to an unsynchronized state takes place for a sufficiently strong but finite coupling strength in the large system limit. We find α(c)=3/2. Frequency entrainment and phase ordering are discussed as a function of α≥1 . The calculations are performed using an expansion about the aligned phase state (spin-wave approximation) and a coarse graining approach. We also generalize the spin-wave results to the d -dimensional problem.

Periodically forced neural mass model: entrainment and complex behavior

Neural mass models (NMM) provide a parsimonious, yet biophysically plausible, way to model mass action in the nervous system [1]. It has been demonstrated that, even in the absence of any time-variant input, they are capable of producing a number of biologically relevant behavior [2]. Moreover, by slowly traversing the parameter space, they can serve as generative models for ordered sequences of oscillatory regimes observed in EEG or MEG data [2]. In the brain, neural circuits are embedded in global networks and may experience high amplitude input from other areas. Such input is very often periodic. Here, we systematically investigate the behavior of a NMM of a cortical area, comprising three neural masses for pyramidal cells and inhibitory and excitatory interneurons, in response to periodic input, as a function of input amplitude and frequency. In our previous work we studied the system with constant input [2]. Two mechanisms for oscillations could be identified: homoclinic and Hopf cycles. Here, we extend our study by considering periodic pulse-like input and systematically vary amplitude and frequency of the input for the widely used parameter set proposed by Jansen and Rit [1]. The input frequency ranges between 4 Hz and 19 Hz including the intrinsic frequency (correponding to the Hopf cycle), and the amplitude values are 1/3, 2/3, 1, 4/3 and 5/3 of amplitude of the Hopf cycle in the unperturbed system. We study the phase space orbits and the time evolution of all variables. The largest Lyapunov exponents and the spectra of the time series are calculated. For studying the relationship of system input and response we compute the frequency-detuning curves, i.e., the frequency difference of response and input plotted against the input frequency. For slight perturbation we found frequency entrainment meaning that the cortical area responds with the stimulus frequency instead of the intrinsic frequency. Away from the entrainment chaotic behavior could be observed, indicated by broadband frequencies in the spectra and positive Lyapunov exponents, whose value in our example is 0.153 (see Figure ​Figure1).1). We also found quasi-periodic and multi-periodic behavior (high-dimensional tori), where the corresponding spectra are discrete with multiple frequency components. Figure 1 Chaotic behavior in neural mass models represented in A time series, B power spectrum, C phase space.

2A2-E18 引き込みを利用した周期入力による三次元受動歩行ロボットの安定化制御

2A2-E18 引き込みを利用した周期入力による三次元受動歩行ロボットの安定化制御

引き込みを利用した周期入力による二足受動歩行ロボットの安定化制御(機械力学,計測,自動制御)

It is difficult to stabilize the three dimensional biped passive walker in various environments because the range of the initial conditions for stable walk is narrow. In this study, a three dimensional biped passive walker was newly designed as a passive walk platform in order to make the success rate of the passive walk high. A new control method that would be able to stabilize the passive walker by using a mechanical oscillator was examined. The target path of the oscillator was generated by utilizing the frequency entrainment in order to synchronize the oscillator movement with the changing motion of the stance leg in the frontal plane. Stability of this passive walker was analytically examined by limit cycle of the frontal movement. A period of the changing motion of the stance leg was synchronized with the period of the swing leg by periodic input generated by the mechanical oscillator. It was demonstrated that the passive walker was stabilized when a frontal motion period was synchronized with a swing leg period in various slope angles. Consequently, it was experimentally examined that the passive walker could be stabilized on various slopes and flat floor.

High frequency entrainment of thalamic neurons by basal ganglia output in the singing bird

High frequency entrainment of thalamic neurons by basal ganglia output in the singing bird

Dynamics of oscillating pulse edges in two-dimensional switch lines

The oscillating motions of a wavefront on a two- dimensional (2D) switch line, i.e., a transmission line periodically loaded with electronic switches (the switch is open for voltages greater than a fixed threshold and closed otherwise), are discussed. In a two-dimensional switch line, the amplitude of the wavefront decays more rapidly than in a one-dimensional switch line, and the oscillation frequency depends on the propagation orientation. The rapid decay of the wavefront, supported by inherent frequency entrainment, is useful for generating high-frequency voltage waves.

Increased phase synchronization and decreased cerebral autoregulation during fainting in the young

Vasovagal syncope may be due to a transient cerebral hypoperfusion that accompanies frequency entrainment between arterial pressure (AP) and cerebral blood flow velocity (CBFV). We hypothesized that cerebral autoregulation fails during fainting; a phase synchronization index (PhSI) between AP and CBFV was used as a nonlinear, nonstationary, time-dependent measurement of cerebral autoregulation. Twelve healthy control subjects and twelve subjects with a history of vasovagal syncope underwent 10-min tilt table testing with the continuous measurement of AP, CBFV, heart rate (HR), end-tidal CO2 (ETCO2), and respiratory frequency. Time intervals were defined to compare physiologically equivalent periods in fainters and control subjects. A PhSI value of 0 corresponds to an absence of phase synchronization and efficient cerebral autoregulation, whereas a PhSI value of 1 corresponds to complete phase synchronization and inefficient cerebral autoregulation. During supine baseline conditions, both control and syncope groups demonstrated similar oscillatory changes in phase, with mean PhSI values of 0.58+/-0.04 and 0.54+/-0.02, respectively. Throughout tilt, control subjects demonstrated similar PhSI values compared with supine conditions. Approximately 2 min before fainting, syncopal subjects demonstrated a sharp decrease in PhSI (0.23+/-0.06), representing efficient cerebral autoregulation. Immediately after this period, PhSI increased sharply, suggesting inefficient cerebral autoregulation, and remained elevated at the time of faint (0.92+/-0.02) and during the early recovery period (0.79+/-0.04) immediately after the return to the supine position. Our data demonstrate rapid, biphasic changes in cerebral autoregulation, which are temporally related to vasovagal syncope. Thus, a sudden period of highly efficient cerebral autoregulation precedes the virtual loss of autoregulation, which continued during and after the faint.

Preliminary evaluation of electroencephalographic entrainment using thalamocortical modelling

Abstract: The concept of linked oscillators in biological control systems has long been established. Frequency entrainment is a predominant explanation behind many biological rhythms. In this paper a preliminary examination of electroencephalographic entrainment is made to survey the possibility and methods of achieving signal entrainment at the highest level of neurological organization and function. A model of the thalamocortical system is employed to generate simulated electroencephalographic signals and is tested in various configurations in the search for entrainment under very simple conditions. Additionally, an analysis of the coupled Van der Pol model of the circadian rhythm controller is performed to identify the possibility of affecting that system with a drastically different coupling input signal. We were able to conclude that overall signal shape can have a significant impact on the entrainment characteristics of the system. Due to the nature of the underlying mathematical structure of the model, by examining the circadian rhythm controller, we found that it is unsuitable for entrainment to an incident entraining signal of much higher frequency.

The forced van der Pol equation

We report on a study of the forced van der Pol equation by solving numerically the differential equation for a variety of values of the parameters ϵ,F and ω. In doing so, many striking and interesting trajectories can be discovered and phenomena such as frequency entrainment, almost periodic solutions, space filling trajectories and seemingly chaotic behaviour are explored. These examples naturally give rise to computer laboratory problems suitable for student research and small group projects.

Forced periodic expression of G 1 cyclins phase-locks the budding yeast cell cycle

Phase-locking (frequency entrainment) of an oscillator, in which a periodic extrinsic signal drives oscillations at a frequency different from the unperturbed frequency, is a useful property for study of oscillator stability and structure. The cell cycle is frequently described as a biochemical oscillator; however, because this oscillator is tied to key biological events such as DNA replication and segregation, and to cell growth (cell mass increase), it is unclear whether phase locking is possible for the cell cycle oscillator. We found that forced periodic expression of the G(1) cyclin CLN2 phase locks the cell cycle of budding yeast over a range of extrinsic periods in an exponentially growing monolayer culture. We characterize the behavior of cells in a pedigree using a return map to determine the efficiency of entrainment to the externally controlled pulse. We quantify differences between mothers and daughters and how synchronization of an expanding population differs from synchronization of a single oscillator. Mothers only lock intermittently whereas daughters lock completely and in a different period range than mothers. We can explain quantitative features of phase locking in both cell types with an analytically solvable model based on cell size control and how mass is partitioned between mother and daughter cells. A key prediction of this model is that size control can occur not only in G(1), but also later in the cell cycle under the appropriate conditions; this prediction is confirmed in our experimental data. Our results provide quantitative insight into how cell size is integrated with the cell cycle oscillator.

Pacific Climate Change and ENSO Activity in the Mid-Holocene

Abstract The authors argue that a reduction to the stochastic forcing of the El Niño–Southern Oscillation (ENSO) wrought by Pacific-wide climate changes in response to mid-Holocene (6000 BP) orbital forcing is a viable hypothesis for the observed reduction of ENSO activity during that time. This conclusion is based on comprehensive analysis of an intermediate coupled model that achieves significant reduction to ENSO variance in response to mid-Holocene orbital forcing. The model’s excellent simulation of the tropical Pacific interannual variability lends credibility to the results. Idealized simulations demonstrate that the mid-Holocene influence is communicated to the tropical Pacific largely via climate changes outside of the tropical Pacific, rather than from insolation changes directly on the tropical Pacific. This is particularly true for changes to the ENSO, but also with changes to the cold tongue annual cycle. Previously proposed mechanisms for teleconnected mid-Holocene ENSO changes, including forcing of ENSO by a strengthened Asian summer monsoon and an increase in the annual cycle forcing on the tropical Pacific leading to a reduction in ENSO activity by frequency entrainment, do not appear to occur in these simulations. Rather, the authors show that the modeled mid-Holocene climate exhibits a pronounced reduction in Pacific meridional mode activity that has been recently shown to be a forcing on ENSO, though the reasons for this reduction are still to be explained. The contrasting nature of the results compared to previous studies highlights the effect of the prevailing ENSO paradigm on this problem. By showing that an externally forced ENSO model is equally capable of explaining mid-Holocene ENSO reduction as its nonlinear, weakly chaotic counterpart, it is demonstrated that the mid-Holocene ENSO data point cannot yet discriminate between these two paradigms of ENSO.

Synchronization of modulated traveling baroclinic waves in a periodically forced, rotating fluid annulus

Frequency entrainment and nonlinear synchronization are commonly observed between simple oscillatory systems, but their occurrence and behavior in continuum fluid systems are much less well understood. Motivated by possible applications to geophysical fluid systems, such as in atmospheric circulation and climate dynamics, we have carried out an experimental study of the interaction of fully developed baroclinic instability in a differentially heated, rotating fluid annulus with an externally imposed periodic modulation of the thermal boundary conditions. In quasiperiodic and chaotic amplitude-modulated traveling wave regimes, the results demonstrate a strong interaction between the natural periodic modulation of the wave amplitude and the externally imposed forcing. This leads to partial or complete phase synchronization. Synchronization effects were observed even with very weak amplitudes of forcing, and were found with both 1:1 and 1:2 frequency ratios between forcing and natural oscillations.

CLIVAR-PAGES-WCRP summer school on El Niño

the role of equatorial waves in the ENSO recharge mechanism. In carrying out these research projects students applied the concepts taught during the lectures, such as the recharge oscillator paradigm, ENSO frequency entrainment, equatorial waves, basin modes, teleconnection patterns and multiplicative noise. Understanding ENSO's past requires an in-depth understanding of the coupled instability mechanisms that underlie ENSO and the annual cycle in the eastern equatorial Pacific. Oversimplified concepts, such as the dynamical thermostat, can mislead paleo-proxy interpretations, and a thorough heat-budget analysis of corresponding model simulations is usually needed to understand ENSO changes that occurred with past climate forcings, such as orbitally induced variations in solar insolation. Numerous coupled general circulation model studies have demonstrated that for certain ENSO regimes a weaker (stronger) annual cycle corresponds to stronger (weaker) ENSO variability. Testing these model-derived relations with paleo-proxy data, such as corals, lake records, speleothems, mollusks, and tree rings, would be an important contribution towards a better understanding of ENSO forcing mechanisms in the past.

SYNCHRONIZATION OF MULTISTABLE SYSTEMS

We present the detailed study of synchronization of two unidirectionally coupled identical systems with coexisting chaotic attractors and analyze system dynamics observed on the route from asynchronous behavior to complete synchronization when the coupling strength is increased. We distinguish three stages of synchronization depending on the coupling strength which can be conventionally divided into three intervals. A relatively weak coupling induces asynchronous intermittent jumps between coexisting attractors and anticipating phase synchronization within windows where the systems stay in similar attractors; an intermediate coupling creates combined attractors that give rise to generalized synchronization in the form of subharmonic frequency entrainment; and a strong coupling results in complete synchronization. The results of numerical simulations are in good agreement with experiments carried out with piecewise-linear Rössler-like electronic circuits.

Frequency-Entrainment Measures in Coupled-Oscillator Systems

We study the frequency entrainment behavior in systems of coupled oscillators. In particular, we pay attention to the measures for detecting the frequency entrainment. We consider a system of coupled oscillators in three dimensions (3D) as one example. Whereas the system does not exhibit the phase synchrony at any nite coupling strength in the thermodynamic limit, the frequencies of the oscillators are known to be entrained in 3D. We illustrate several measures that have been used in the previous studies to detect the frequency entrainment and compare their scaling behaviors near criticality. Via a nite-size scaling analysis combined with the recently reported critical exponents = 0 and = 2 in 3D, we reveal that the Edward-Anderson-type order parameter popularly used in the spin glass systems can, indeed, be used as one good order parameter to detect frequency entrainment.