Contributors: Eugene Grichuk, Margarita Kuzmina, Eduard Manykin

Date: 2010-09-26

qubit simulates the behavior of electric field of polarized light beam...qubit model has been designed as a stochastic oscillator formed by a pair...qubits that is exploited as a computation resource in one-way quantum ...oscillators is proposed for modeling of a cluster of entangled qubits ...oscillators with chaotically modulated limit cycle radii and frequencies...one-qubit gates are suggested. Changing of cluster entanglement degree...qubit cluster, is designed, and system of equations for network dynamics...oscillators...qubit model has been designed as a stochastic oscillator formed by a pair ... A network of coupled stochastic oscillators is proposed for modeling of a cluster of entangled qubits that is exploited as a computation resource in one-way quantum computation schemes. A qubit model has been designed as a stochastic oscillator formed by a pair of coupled limit cycle oscillators with chaotically modulated limit cycle radii and frequencies. The qubit simulates the behavior of electric field of polarized light beam and adequately imitates the states of two-level quantum system. A cluster of entangled qubits can be associated with a beam of polarized light, light polarization degree being directly related to cluster entanglement degree. Oscillatory network, imitating qubit cluster, is designed, and system of equations for network dynamics has been written. The constructions of one-qubit gates are suggested. Changing of cluster entanglement degree caused by measurements can be exactly calculated.

Contributors: Howan Leung, Cannon X.L. Zhu, Danny T.M. Chan, Wai S. Poon, Lin Shi, Vincent C.T. Mok, Lawrence K.S. Wong

Date: 2015-01-01

High-frequency oscillations...frequency ictal patterns, ictal high-frequency oscillations, hyperexcitability...frequency oscillations, CFIP=conventional frequency ictal patterns. ...High-frequency oscillations (HFOs, 80–500Hz) from intracranial electroencephalography ... High-frequency oscillations (HFOs, 80–500Hz) from intracranial electroencephalography (EEG) may represent a biomarker of epileptogenicity for epilepsy. We explored the relationship between ictal HFOs and hyperexcitability with a view to improving surgical outcome.

Contributors: Eric Maris, Marieke van Vugt, Michael Kahana

Date: 2011-01-15

frequency spectra of a coupling oscillation and the associated phase-coupled...high-frequency bursts that are coupled to a common low-frequency oscillation...frequency spectra produced by the tensor decomposition. All identified...oscillation. This mechanism requires multiple physiologically different...frequency spectrum. We showed that, with this source definition, the array...frequency spectra (both real-valued), which is exactly the structure that...high-frequency oscillations that are phase-coupled to a low-frequency ...high-frequency oscillations. Using human intracranial EEG (iEEG) data,...oscillation. In panel d, with green and index f, we show the frequency...low-frequency coupling oscillation and the others generating phase-coupled...frequencies of the coupling oscillations (vertical axis). The central ...frequency spectrum) and in terms of the neuronal network that generates...frequency spectra, then they can be extracted by means of tensor decomposition...oscillations are much more widespread than the ones for the associated...frequency of the coupling oscillation), respectively, y-axes (showing ... Spatially distributed coherent oscillations provide temporal windows of excitability that allow for interactions between distinct neuronal groups. It has been hypothesized that this mechanism for neuronal communication is realized by bursts of high-frequency oscillations that are phase-coupled to a low-frequency spatially distributed coupling oscillation. This mechanism requires multiple physiologically different interacting sources, one generating the low-frequency coupling oscillation and the others generating phase-coupled high-frequency oscillations. Using human intracranial EEG (iEEG) data, we provide evidence for multiple oscillatory patterns, as characterized on the basis of their spatial maps (topographies) and their frequency spectra. In fact, we show that the spatial maps for the coupling oscillations are much more widespread than the ones for the associated phase-coupled bursts. Second, in the majority of the patterns of phase-amplitude coupling (PAC), phase-coupled bursts of high-frequency activity are synchronized across brain areas. Third and last, working memory operations affect the PAC strength in a heterogeneous way: in some PAC patterns, working memory operations increase their strength, whereas in others they decrease it.

Contributors: Li Wang, Qingmei Kong, Ke Li, Yunai Su, Yawei Zeng, Qinge Zhang, Wenji Dai, Mingrui Xia, Gang Wang, Zhen Jin

Date: 2016-02-12

Frequency main effects on ALFF. Hot colors represent increased ALFF in...frequency (slow-4 and slow-5) interaction effects on ALFF. The regions...low-frequency oscillation (LFO) of major depressive disorder (MDD) patients...frequency (slow-4 and slow-5) interaction effects on ALFF. ...frequency dependent....Low-frequency oscillation...Frequency dependence...frequency interaction effects on ALFF (hot colors): the left ventromedial...frequency on ALFF. (a) The group main effects on ALFF. Hot colors represent ... We conducted this fMRI study to examine whether the alterations in amplitudes of low-frequency oscillation (LFO) of major depressive disorder (MDD) patients were frequency dependent.

Contributors: Iori Ito, Maxim Bazhenov, Rose Chik-ying Ong, Baranidharan Raman, Mark Stopfer

Date: 2009-12-10

frequency was typically limited to the LFP frequency. (E) Frequency of...Oscillation Coherence, Not Frequency (A) EAG traces revealed total ORN...frequency of fast oscillation changed not at all or only slightly across...oscillation frequency. However, changing the concentration of the odor...Frequency of MB-LFP oscillations changed in parallel to the odor input...frequency (compare B and the Figure 1C) we observed in vivo. ...oscillations suddenly slowed as net olfactory receptor neuron (ORN) output...oscillations? In the olfactory system of the moth, we found that odors...frequency. Our recordings in vivo and computational models based on these...oscillation frequency is set by the adaptation and saturation of this ... In many species, sensory stimuli elicit the oscillatory synchronization of groups of neurons. What determines the properties of these oscillations? In the olfactory system of the moth, we found that odors elicited oscillatory synchronization through a neural mechanism like that described in locust and Drosophila. During responses to long odor pulses, oscillations suddenly slowed as net olfactory receptor neuron (ORN) output decreased; thus, stimulus intensity appeared to determine oscillation frequency. However, changing the concentration of the odor had little effect upon oscillatory frequency. Our recordings in vivo and computational models based on these results suggested that the main effect of increasing odor concentration was to recruit additional, less well-tuned ORNs whose firing rates were tightly constrained by adaptation and saturation. Thus, in the periphery, concentration is encoded mainly by the size of the responsive ORN population, and oscillation frequency is set by the adaptation and saturation of this response.

Contributors: Abdul-Niby, M., Alameen, M., Baitie, H.

Date: 2016-12-18

frequency synthesis, quadrature signal generation and phase locked loops...oscillator (ILO) of 35MHz frequency. Phase shifters at high frequencies...oscillator...Oscillating systems, locking of the oscillators can take place for injected...frequency to nth harmonics of the free-running frequency. In this paper ... In Self Oscillating systems, locking of the oscillators can take place for injected signals close in frequency to nth harmonics of the free-running frequency. In this paper, we present a simple design for digital phase shift control by using a harmonically injection locked oscillator (ILO) of 35MHz frequency. Phase shifters at high frequencies are essential in many communication system applications such as frequency synthesis, quadrature signal generation and phase locked loops (PLLs).

Contributors: George M. Ibrahim, Simeon M. Wong, Ryan A. Anderson, Gabrielle Singh-Cadieux, Tomoyuki Akiyama, Ayako Ochi, Hiroshi Otsubo, Tohru Okanishi, Taufik A. Valiante, Elizabeth Donner

Date: 2014-01-01

frequency oscillations at which pHFO amplitudes were maximal was inconsistent...oscillations (p<0.01). These results suggest that increased CFC between...frequency oscillations (pHFOs) have been proposed to be robust markers...oscillations, whereas pathological ripple amplitudes preferentially occurred...frequency amplitude by low-frequency phase. In the seizure-onset zone,...oscillations is observed. There is also less cross-frequency coupling ...frequency range has been shown to be modulated by phase of lower frequency...oscillations during the ictal period. In the interictal period, no specific...frequency oscillations...Cross-frequency coupling...frequency phase, we measured the preferred slow oscillatory phase at which...frequencies (x-axis) by the phases of other narrow-band frequencies (y-axis...oscillations (p=0.14 and p=0.68, respectively). At seizure termination...frequency oscillations, sorted by concurrent low-frequency phase into ...oscillations. Here, we tested the hypothesis that dynamic cross-frequency ... Pathological high frequency oscillations (pHFOs) have been proposed to be robust markers of epileptic cortex. Oscillatory activity below this frequency range has been shown to be modulated by phase of lower frequency oscillations. Here, we tested the hypothesis that dynamic cross-frequency interactions involving pHFOs are concentrated within the epileptogenic cortex. Intracranial electroencephalographic recordings from 17 children with medically-intractable epilepsy secondary to focal cortical dysplasia were obtained. A time-resolved analysis was performed to determine topographic concentrations and dynamic changes in cross-frequency amplitude-to-phase coupling (CFC). CFC between pHFOs and the phase of theta and alpha rhythms was found to be significantly elevated in the seizure-onset zone compared to non-epileptic regions (p<0.01). Data simulations showed that elevated CFC could not be attributed to the presence of sharp transients or other signal properties. The phase of low frequency oscillations at which pHFO amplitudes were maximal was inconsistent at seizure initiation, yet consistently at the trough of the low frequency rhythm at seizure termination. Amplitudes of pHFOs were most significantly modulated by the phase of alpha-band oscillations (p<0.01). These results suggest that increased CFC between pHFO amplitude and alpha phase may constitute a marker of epileptogenic brain areas and may be relevant for understanding seizure dynamics.

Contributors: Jiwoo Hong, Young Kwon Kim, Kwan Hyoung Kang, Joonwon Kim, Sang Joon Lee

Date: 2014-01-01

oscillation dynamics of a sessile drop, such as resonance frequency and...frequencies (frequency range of 20–110Hz in which the first and second...oscillation. ...frequency, but strongly affects the oscillation amplitude and peak width...oscillation amplitude, in response to different AC voltages (80 and 100Vrms...frequency...oscillating drops with different viscosities along with AC frequency at...frequency. ...oscillating drops with different viscosities for different frequencies...frequency. In addition, drop oscillation in the resonance mode is no longer...oscillation...Frequency response at harmonic and subharmonic frequencies. ... The effects of drop viscosity on oscillation dynamics of a sessile drop, such as resonance frequency and oscillation amplitude, in response to different AC voltages (80 and 100Vrms, corresponding to the electrowetting number η of 0.25 and 0.39, respectively) and frequencies (frequency range of 20–110Hz in which the first and second resonance frequencies exist) were investigated, based on both experiments and theoretical modeling. The results show that drop viscosity rarely affects resonance frequency, but strongly affects the oscillation amplitude and peak width of the resonance frequency. In addition, drop oscillation in the resonance mode is no longer observed, when the drop viscosity is over the critical value, which increases with applied AC voltage. A theoretical model predicts the oscillation dynamics of sessile drops within the error level of ±5%, except for the drop with high viscosity (60mPas). Moreover, the friction coefficient obtained by fitting the theoretical models is nearly proportional to the drop viscosity. Finally, an empirical relationship, in which the maximum amplitude is inversely proportional to the drop viscosity, is obtained.

Contributors: Kenji Kirihara, Anthony J. Rissling, Neal R. Swerdlow, David L. Braff, Gregory A. Light

Date: 2012-05-15

time-frequency points at p < .01. ...cross-frequency coupling...cross-frequency coupling of gamma and theta oscillations in response to...oscillations (black line). Note that excitatory and inhibitory phase may...oscillations is modulated by the phase of ongoing theta oscillations. ...oscillations in the gamma frequency range (∼40 Hz) is associated with ...oscillations...cross-frequency coupling. Gamma oscillations (red and blue lines) are ...Oscillations ...oscillations are modulated by the phase of theta waves, and this cross-frequency...gamma-frequency steady-state stimulation and if abnormal neural oscillatory ... Schizophrenia patients have deficits across a broad range of important cognitive and clinical domains. Synchronization of oscillations in the gamma frequency range (∼40 Hz) is associated with many normal cognitive functions and underlies at least some of the deficits observed in schizophrenia patients. Recent studies have demonstrated that gamma oscillations are modulated by the phase of theta waves, and this cross-frequency coupling indicates that a complex and hierarchical organization governs neural oscillatory dynamics. The aims of the present study were to determine if schizophrenia patients have abnormalities in the amplitude, synchrony, and cross-frequency coupling of gamma and theta oscillations in response to gamma-frequency steady-state stimulation and if abnormal neural oscillatory dynamics are associated with cognitive deficits in schizophrenia.

Contributors: Bassam V. Atallah, Massimo Scanziani

Date: 2009-05-28

frequencies. The amplitude and frequency of these oscillations are continuously...Frequency in Simple Model of CA3 Circuit (A) Average excitatory (gE, red...Oscillation Amplitude Predicts Latency to Next Oscillation Cycle (A) (...frequencies. Summary of peak coherence frequency (bottom) and peak coherence...oscillation cycle recorded in the LFP, i.e., oscillation triggered average...oscillation cycle independent of oscillation amplitude. ...oscillation frequency. So, by rapidly balancing excitation with inhibition...oscillation predicts the interval to the next. Using in vivo and in vitro...oscillation amplitude and frequency vary rapidly, from one cycle to the...oscillations over a wide band of frequencies. ... Neurons recruited for local computations exhibit rhythmic activity at gamma frequencies. The amplitude and frequency of these oscillations are continuously modulated depending on stimulus and behavioral state. This modulation is believed to crucially control information flow across cortical areas. Here we report that in the rat hippocampus gamma oscillation amplitude and frequency vary rapidly, from one cycle to the next. Strikingly, the amplitude of one oscillation predicts the interval to the next. Using in vivo and in vitro whole-cell recordings, we identify the underlying mechanism. We show that cycle-by-cycle fluctuations in amplitude reflect changes in synaptic excitation spanning over an order of magnitude. Despite these rapid variations, synaptic excitation is immediately and proportionally counterbalanced by inhibition. These rapid adjustments in inhibition instantaneously modulate oscillation frequency. So, by rapidly balancing excitation with inhibition, the hippocampal network is able to swiftly modulate gamma oscillations over a wide band of frequencies.