TMS entrains occipital alpha activity: Individual alpha frequency predicts the strength of entrained phase-locking

2021 ◽  
Author(s):  
Yong-Jun Lin ◽  
Lavanya Shukla ◽  
Laura Dugué ◽  
Antoni Valero-Cabré ◽  
Marisa Carrasco
Keyword(s):  
Cortical Excitability ◽  
Phase Locking ◽  
Time Windows ◽  
Oscillation Amplitude ◽  
Occipital Cortex ◽  
Input Frequency ◽  
Oscillation Phase ◽  
Alpha Frequency ◽  
Frequency Specificity ◽  
Individual Alpha Frequency

Abstract Parieto-occipital alpha rhythms (8–12 Hz) underlie cortical excitability and influence visual performance. Whether the synchrony of intrinsic alpha rhythms in the occipital cortex can be entrained by transcranial magnetic stimulation (TMS) is an open question. We applied 4-pulse, 10-Hz rhythmic TMS to entrain intrinsic alpha oscillators targeting right V1/V2, and tested four predictions with concurrent electroencephalogram (EEG): (1) progressive enhancement of entrainment across time windows, (2) output frequency specificity, (3) dependence on the intrinsic oscillation phase, and (4) input frequency specificity to individual alpha frequency (IAF) in the neural signatures. Two control conditions with an equal number of pulses and duration were arrhythmic-active and rhythmic-sham stimulation. The results confirmed the first three predictions. Rhythmic TMS bursts significantly entrained local neural activity. Near the stimulation site, evoked oscillation amplitude and inter-trial phase coherence (ITPC) were increased for 2 and 3 cycles, respectively, after the last TMS pulse. Critically, ITPC following entrainment positively correlated with IAF rather than with the degree of similarity between IAF and the input frequency (10 Hz). Thus, we entrained alpha-band activity in occipital cortex for ~ 3 cycles (~ 300 ms), and IAF predicts the strength of entrained occipital alpha phase synchrony indexed by ITPC.

scholarly journals Transcranial magnetic stimulation entrains alpha oscillatory activity in occipital cortex

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yong-Jun Lin ◽  
Lavanya Shukla ◽  
Laura Dugué ◽  
Antoni Valero-Cabré ◽  
Marisa Carrasco
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Time Windows ◽  
Oscillation Amplitude ◽  
Occipital Cortex ◽  
Oscillatory Activity ◽  
Input Frequency ◽  
Oscillation Phase ◽  
Frequency Specificity

AbstractParieto-occipital alpha rhythms (8–12 Hz) underlie cortical excitability and influence visual performance. Whether the synchrony of intrinsic alpha rhythms in the occipital cortex can be entrained by transcranial magnetic stimulation (TMS) is an open question. We applied 4-pulse, 10-Hz rhythmic TMS to entrain intrinsic alpha oscillators targeting right V1/V2, and tested four predictions with concurrent electroencephalogram (EEG): (1) progressive enhancement of entrainment across time windows, (2) output frequency specificity, (3) dependence on the intrinsic oscillation phase, and (4) input frequency specificity to individual alpha frequency (IAF) in the neural signatures. Two control conditions with an equal number of pulses and duration were arrhythmic-active and rhythmic-sham stimulation. The results confirmed the first three predictions. Rhythmic TMS bursts significantly entrained local neural activity. Near the stimulation site, evoked oscillation amplitude and inter-trial phase coherence (ITPC) were increased for 2 and 3 cycles, respectively, after the last TMS pulse. Critically, ITPC following entrainment positively correlated with IAF rather than with the degree of similarity between IAF and the input frequency (10 Hz). Thus, we entrained alpha-band activity in occipital cortex for ~ 3 cycles (~ 300 ms), and IAF predicts the strength of entrained occipital alpha phase synchrony indexed by ITPC.

Individual Alpha Frequency Relates to the Sound-Induced Flash Illusion

2017 ◽  
Vol 30 (6) ◽  
pp. 565-578 ◽  
Author(s):  
Julian Keil ◽  
Daniel Senkowski
Keyword(s):  
Cortical Excitability ◽  
Multisensory Processing ◽  
Audiovisual Integration ◽  
Source Analysis ◽  
Neural Oscillations ◽  
Sensory Stimuli ◽  
Alpha Frequency ◽  
The Individual ◽  
Individual Alpha Frequency ◽  
The Relationship

Ongoing neural oscillations reflect fluctuations of cortical excitability. A growing body of research has underlined the role of neural oscillations for stimulus processing. Neural oscillations in the alpha band have gained special interest in electrophysiological research on perception. Recent studies proposed the idea that neural oscillations provide temporal windows in which sensory stimuli can be perceptually integrated. This also includes multisensory integration. In the current high-density EEG-study we examined the relationship between the individual alpha frequency (IAF) and cross-modal audiovisual integration in the sound-induced flash illusion (SIFI). In 26 human volunteers we found a negative correlation between the IAF and the SIFI illusion rate. Individuals with a lower IAF showed higher audiovisual illusions. Source analysis suggested an involvement of the visual cortex, especially the calcarine sulcus, for this relationship. Our findings corroborate the notion that the IAF affects the cross-modal integration of auditory on visual stimuli in the SIFI. We integrate our findings with recent observations on the relationship between audiovisual integration and neural oscillations and suggest a multifaceted influence of neural oscillations on multisensory processing.

scholarly journals Does alpha phase modulate visual target detection? Three experiments with tACS phase-based stimulus presentation

2019 ◽  
Author(s):  
Tom A. de Graaf ◽  
Alix Thomson ◽  
Shanice E.W. Janssens ◽  
Sander van Bree ◽  
Sanne ten Oever ◽  
...  
Keyword(s):  
Visual Processing ◽  
Cortical Excitability ◽  
Reaction Times ◽  
Stimulus Presentation ◽  
Occipital Cortex ◽  
Primary Outcome Measure ◽  
Alpha Phase ◽  
Detection Rates ◽  
Alpha Frequency ◽  
Oscillatory Pattern

AbstractIn recent years the influence of alpha (7-13 Hz) phase on visual processing has received a lot of attention. Magneto-/encephalography (M/EEG) studies showed that alpha phase indexes visual excitability and task performance. If occipital alpha phase is functionally relevant, the phase of occipital alpha-frequency transcranial alternating current stimulation (tACS) could modulate visual processing. Visual stimuli presented at different pre-determined, experimentally controlled, phases of the entraining tACS signal should then result in an oscillatory pattern of visual performance. We studied this in a series of experiments. In experiment one, we applied 10 Hz tACS to right occipital cortex (O2) and used independent psychophysical staircases to obtain contrast thresholds for detection of visual gratings in left or right hemifield, in six equidistant tACS phase conditions. In experiments two and three, tACS was at EEG-based individual peak alpha frequency. In experiment two, we measured detection rates for gratings with (pseudo-)fixed contrast levels. In experiment three, participants detected brief luminance changes in a custom-built LED device, at eight equidistant alpha phases. In none of the experiments did the primary outcome measure over phase conditions consistently reflect a one-cycle sinusoid as predicted. However, post-hoc analyses of reaction times (RT) suggested that tACS alpha phase did modulate RT in both experiments 1 and 2 (not measured in experiment 3). This observation is in line with the idea that alpha phase causally gates visual inputs through cortical excitability modulation.

scholarly journals Volitional Control of Individual Neurons in the Human Brain

2020 ◽  
Author(s):  
Kramay Patel ◽  
Chaim N. Katz ◽  
Suneil K. Kalia ◽  
Milos R. Popovic ◽  
Taufik A. Valiante
Keyword(s):  
Human Brain ◽  
Firing Rate ◽  
Phase Locking ◽  
Brain Structures ◽  
Human Memory ◽  
Skill Learning ◽  
Oscillation Phase ◽  
Improved Performance ◽  
Beta Frequency ◽  
Interconnected Structure

AbstractCan the human brain, a complex interconnected structure of over 80 billion neurons learn to control itself at the most elemental scale – a single neuron. We directly linked the firing rate of a single (direct) neuron to the position of a box on a screen, which participants tried to control. Remarkably, all subjects upregulated the firing rate of the direct neuron in memory structures of their brain. Learning was accompanied by improved performance over trials, simultaneous decorrelation of the direct neuron to local neurons, and direct neuron to beta frequency oscillation phase-locking. Such previously unexplored neuroprosthetic skill learning within memory related brain structures, and associated beta frequency phase-locking implicates the ventral striatum. Our demonstration that humans can volitionally control neuronal activity in mnemonic structures, may provide new ways of probing the function and plasticity of human memory without exogenous stimulation.

scholarly journals Envelope analysis of the human alpha rhythm

2021 ◽  
Author(s):  
Víctor Manuel Hidalgo ◽  
Javier Díaz ◽  
Jorge Mpodozis ◽  
Juan-Carlos Letelier
Keyword(s):  
Gaussian Noise ◽  
Alpha Rhythm ◽  
Phase Locking ◽  
Gaussian White Noise ◽  
Occipital Cortex ◽  
Neural Population ◽  
Envelope Analysis ◽  
Weakly Coupled ◽  
Neural Signal Analysis ◽  
New Interpretation

The origin of the human alpha rhythm has been a matter of debate since Lord Adrian attributed it to synchronous neural populations in the occipital cortex. While some authors have pointed out the Gaussian characteristics of the alpha rhythm, their results have been repeatedly disregarded in favor of Adrian′s interpretation; even though the first EEG Gaussianity reports can be traced back to the origins of EEG. Here we revisit this problem using the envelope analysis — a method that relies on the fact that the coefficient of variation of the envelope (CVE) for continuous-time zero-mean Gaussian white noise (as well as for any filteredsub-band) is equal to √(4−π)/π≈0.523, thus making the CVE a fingerprint for Gaussianity. As a consequence, any significant deviation from Gaussianity is linked to synchronous neural dynamics. Low-CVE signals come from phase-locking dynamics, while mid-CVE signals constitute Gaussian noise. High-CVE signals have been linked to unsteady dynamics in populations of nonlinear oscillators. We analyzed occipital EEG and iEEG data from massive public databases and the order parameter of a population of weakly coupled oscillators using the envelope analysis. Our results showed that the human alpha rhythm can be characterized as a rhythmic, Gaussian, or pulsating signal due to intra- and inter-subject variability. Furthermore, Fourier analysis showed that the canonical spectral peak at≈10[Hz] is present in all three CVE classes, thus demonstrating that this same peak can be produced by rhythms, Gaussian noise, and pulsating ripples. Alpha-like signals obtained from a population of non-linear oscillators showed a different CVE depending only on the coupling constant, suggesting that the same neural population can produce the amplitude modulation patterns observed in experimental data. iEEG data, however, was found to be mostly Gaussian, specially the signals recorded from the calcarine cortex. These results suggest that a new interpretation for EEG event-related synchronization/desynchronization (ERS/ERD) may be needed. Envelope analysis constitutes a novel complement to traditional Fourier-based methods for neural signal analysis relating amplitude modulations (CVE) to signal energy.

scholarly journals TMS-EEG indexes abnormal GABAergic signalling in patients with schizophrenia

BJPsych Open ◽  
2021 ◽  
Vol 7 (S1) ◽  
pp. S52-S52
Author(s):  
Sukhwinder S Shergill ◽  
Viviana Santoro ◽  
Lorenzo Rocchi ◽  
Meng Di Hou ◽  
Isabella Premoli
Keyword(s):  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Time Windows ◽  
Detailed Examination ◽  
Clinical Population ◽  
Gaba A ◽  
Non Invasive ◽  
Resting Motor Threshold ◽  
Gated Channel ◽  
Excitatory Neurotransmission

AimsTranscranial magnetic stimulation (TMS) is a non-invasive brain stimulation tool designed to probe the strength of inhibitory and excitatory neurotransmission in the cortex. Combined with electromyography, paired-pulse TMS paradigms have revealed a deficit in inhibition mediated by GABA-A receptors in patients with schizophrenia. Combined TMS-electroencephalography (TMS-EEG) provides a more detailed examination of cortical excitability and may shed more light into the pathophysiology of schizophrenia. Of the various peaks of the TMS-evoked EEG signal, responses at 45 (N45) and 100 ms (N100) likely reflect GABA-A and GABA-B receptor-mediated inhibition, respectively. Responses at 25 ms (P25) are affected by voltage-gated channel ligands, whereas glutamatergic processes may be related to the P70 component. We here aim to systematically investigate the role of these neural processes in patients with schizophrenia by using TMS-EEG.MethodTMS-evoked EEG potentials (TEPs) were recorded in patients with schizophrenia (n = 19) and in age-matched healthy controls (n = 17). 150 TMS pulses at 90% of resting motor threshold were applied over the left primary motor cortex during EEG recording. Differences in TEPs between the two groups were analysed for all electrodes and for time windows corresponding to each TEP (P25: 0.015-0.035 ms; N45: 0.035-0.06 ms; P70: 0.035-0.06 ms; N100: 0.09-0.14ms) by applying multiple independent sample t-tests. Further, a cluster-based permutation analysis approach was implemented to correct for multiple comparisons.ResultCompared to controls, patients showed amplitude reduction for the P25 (negative and positive cluster; p < 0.001 and p = 0.04, respectively), N45 (negative and positive cluster; p < 0.001 and p = 0.001, respectively) and P70 component (negative and positive cluster; p = 0.04 and p = 0.004, respectively).ConclusionThere results extend on previous literature about impairment of GABA-A receptor mediated inhibition in schizophrenia, as demonstrated by the N45 amplitude reduction, whereas no significant differences in GABA-B index (i.e., N100) were revealed. Our results also showed that, although specific mechanisms underlying P25 and P70 have not been fully elucidated yet, excitatory neurotransmission is altered in this clinical population. To conclude, TMS-EEG may provide a more comprehensive view of the inhibitory and excitatory mechanisms involved in the pathophysiology of schizophrenia.

scholarly journals Modulation of Individual Alpha Frequency with tACS shifts Time Perception

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Giovanna Mioni ◽  
Adam Shelp ◽  
Candice T Stanfield-Wiswell ◽  
Keri A Gladhill ◽  
Farah Bader ◽  
...  
Keyword(s):  
Time Perception ◽  
Human Subjects ◽  
Peak Frequency ◽  
Alpha Oscillations ◽  
Standard Interval ◽  
Alpha Frequency ◽  
Temporal Intervals ◽  
Transcranial Alternating Current Stimulation ◽  
Speed Effect ◽  
Individual Alpha Frequency

Abstract Previous studies have linked brain oscillation and timing, with evidence suggesting that alpha oscillations (10 Hz) may serve as a “sample rate” for the visual system. However, direct manipulation of alpha oscillations and time perception has not yet been demonstrated. To test this, we had 18 human subjects perform a time generalization task with visual stimuli. Additionally, we had previously recorded resting-state EEG from each subject and calculated their individual alpha frequency (IAF), estimated as the peak frequency from the mean spectrum over posterior electrodes between 8 and 13 Hz. Participants first learned a standard interval (600 ms) and were then required to judge if a new set of temporal intervals were equal or different compared with that standard. After learning the standard, participants performed this task while receiving occipital transcranial Alternating Current Stimulation (tACS). Crucially, for each subject, tACS was administered at their IAF or at off-peak alpha frequencies (IAF ± 2 Hz). Results demonstrated a linear shift in the psychometric function indicating a modification of perceived duration, such that progressively “faster” alpha stimulation led to longer perceived intervals. These results provide the first evidence that direct manipulations of alpha oscillations can shift perceived time in a manner consistent with a clock speed effect.

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