Modeling spectral changes following stimulation: Is there an event-related shift in 1/f activity?

Neural activity contains oscillatory components (i.e., narrowband oscillations) and non-oscillatory components (e.g., event-related potentials [ERPs] and 1/f-like background activity). Here, surface-level EEG data was analyzed to investigate how the spectral content of neural activity below 25 Hz changes from before to after an event. We focused on changes in non-oscillatory background activity, a spectral component often assumed to be static across time in time-frequency analyses. During a simple auditory perception task (n = 46) and an auditory oddball task (n = 23), we found an apparent increase in the offset and a decrease in the slope of 1/f activity from before to after a tone. Importantly, however, these changes in non-oscillatory background activity were almost completely accounted for by the emergence of ERPs in response to the stimulus in frequencies below the alpha range (8-12 Hz). Our findings suggest that post-event spectral changes below 25 Hz can be modelled as the sum of pre-event non-oscillatory activity, the spectrum of the ERP, and an independent alpha component that is modulated in amplitude, but not elicited, by the event. Theta activity (4-8 Hz), however, was not present before the event and appeared to be phase-locked to it. The theoretical and methodological implications of our findings regarding the nature and origin of 1/f activity, and the interpretation of low-frequency activity in the time-frequency domain are discussed.

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Stereotactic electroencephalography in humans reveals multisensory signal in early visual and auditory cortices

10.1101/549733 ◽

2019 ◽

Cited By ~ 2

Author(s):

Stefania Ferraro ◽

Markus J. Van Ackeren ◽

Roberto Mai ◽

Laura Tassi ◽

Francesco Cardinale ◽

...

Keyword(s):

Visual Cortex ◽

Auditory Cortex ◽

Auditory Processing ◽

Multisensory Processing ◽

Low Frequency ◽

Event Related Potentials ◽

Stimulus Onset ◽

Oscillatory Activity ◽

Visual Responses ◽

Related Potentials

AbstractUnequivocally demonstrating the presence of multisensory signals at the earliest stages of cortical processing remains challenging in humans. In our study, we relied on the unique spatio-temporal resolution provided by intracranial stereotactic electroencephalographic (SEEG) recordings in patients with drug-resistant epilepsy to characterize the signal extracted from early visual (calcarine and pericalcarine) and auditory (Heschl’s gyrus and planum temporale) regions during a simple audio-visual oddball task. We provide evidences that both cross-modal responses (visual responses in auditory cortex or the reverse) and multisensory processing (alteration of the unimodal responses during bimodal stimulation) can be observed in intracranial event-related potentials (iERPs) and in power modulations of oscillatory activity at different temporal scales within the first 150 ms after stimulus onset. The temporal profiles of the iERPs are compatible with the hypothesis that MSI occurs by means of direct pathways linking early visual and auditory regions. Our data indicate, moreover, that MSI mainly relies on modulations of the low-frequency bands (foremost the theta band in the auditory cortex and the alpha band in the visual cortex), suggesting the involvement of feedback pathways between the two sensory regions. Remarkably, we also observed high-gamma power modulations by sounds in the early visual cortex, thus suggesting the presence of neuronal populations involved in auditory processing in the calcarine and pericalcarine region in humans.

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In search for the most optimal EEG method: A practical evaluation of a water-based electrode EEG system

10.1101/2021.04.28.441825 ◽

2021 ◽

Author(s):

M. Topor ◽

B. Opitz ◽

P. J. A. Dean

Keyword(s):

Signal To Noise Ratio ◽

Flanker Task ◽

Low Frequency ◽

Event Related Potentials ◽

Event Related Potential ◽

Specific System ◽

Time Frequency ◽

Beta Power ◽

Water Based ◽

Related Potentials

AbstractThe study assessed a new mobile electroencephalography (EEG) system with water-based electrodes for its applicability in time-frequency and event related potential research. It was compared to a standard gel-based wired system. EEG was recorded on two occasions as participants completed the flanker task, first with the gel-based system followed by the water-based system. Technical and practical considerations for the application of the new water-based system are reported based on the participant and experimenter experiences. Empirical comparisons focused on EEG data noise levels, frequency power across four bands including theta, alpha, low beta and high beta and P300 and ERN event related potential components. The water-based system registered more noise compared to the gel-based system which resulted in increased loss of data during artefact rejection. Signal to noise ratio was significantly lower for the water-based system in the parietal channels which impacted the observed parietal beta power. It also led to a shift in topography of the maximal P300 activity from parietal to frontal regions. It is also evident, that the water-based system may be prone to slow drift noise which may affect the reliability and consistency of low frequency band analyses. Considerations for the use of this specific system for time-frequency and event related potentials are discussed.

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Electrophysiological mechanisms underlying ERP amplitude reduction in patients with schizophrenia: A time-frequency analysis

European Psychiatry ◽

10.1016/j.eurpsy.2016.01.085 ◽

2016 ◽

Vol 33 (S1) ◽

pp. S104-S104

Author(s):

D.D. Marasco ◽

A. Vignapiano ◽

G. Di Lorenzo ◽

A. Mucci ◽

M. Altamura ◽

...

Keyword(s):

Phase Locking ◽

Event Related Potentials ◽

Time Frequency ◽

Auditory Oddball ◽

Relative Contribution ◽

Power Increase ◽

Delta Band ◽

Related Potentials ◽

Competing Interest ◽

Trial Phase

BackgroundIt is hypothesized that the event-related potentials are generated by different electrophysiological mechanisms, i.e., event-related power increase and enhanced degree of phase-locking over trial. The study aimed to characterize the relative contribution of these mechanisms to the ERP in patients with schizophrenia (SCZ).Materials and methodsOne hundred and fifteen chronic stabilized SCZ and 62 healthy controls (HC) recruited to the study of the Italian Network for Research on Psychoses were included. Scalp potentials were recorded during a standard auditory oddball task. Stimulus-locked segments were extracted for all standard trials and correctly hit target trials. Trials contaminated by other artifacts were rejected. For each subject and stimulus type the event-related spectral perturbation (ERSP) and the inter-trial-coherence (ITC) were computed to assess event-related power increase and inter-trial phase-locking. The two groups were compared using Student's t-test followed by Bonferroni correction for multiple comparisons.ResultsSCZ presented a reduced amplitude of both N100 and P3b. For both standard and target stimuli, at Cz and Pz, ERSP was reduced in SCZ in the delta-theta band (from 0 up to 400 ms). The ITC index, at the same channels, was reduced in SCZ in the delta band for standard stimuli (from 0 to 300 ms), and in both delta and theta bands for target stimuli (from 300 to 400 ms).ConclusionsOur results indicate that alterations of both mechanisms are involved in N100 and P3b amplitude reduction observed in SCZ. Inter-trial phase-locking abnormalities for N100 were limited to the delta band, while for P3b involved delta and theta frequencies.Disclosure of interestThe authors have not supplied their declaration of competing interest.

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P300 and Heart Rate Variability Recorded Simultaneously in Meditation

Clinical EEG and Neuroscience ◽

10.1177/1550059418790717 ◽

2018 ◽

Vol 50 (3) ◽

pp. 161-171 ◽

Cited By ~ 2

Author(s):

Shirley Telles ◽

Deepeshwar Singh ◽

K. V. Naveen ◽

Subramanya Pailoor ◽

Nilkamal Singh ◽

...

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Repeated Measures ◽

Sympathetic Activity ◽

Low Frequency ◽

Event Related Potentials ◽

Mental States ◽

Average Heart Rate ◽

Auditory Oddball ◽

Related Potentials

Sympathetic activation is required for attention. Separate studies have shown that meditation ( a) improves attention and ( b) reduces sympathetic activity. The present study assessed attention with the P300 and sympathetic activity with heart rate variability (HRV). Forty-seven male subjects (group mean age ± SD, 21.6 ± 3.4 years) were assessed in 4 mental states: ( a) random thinking, ( b) nonmeditative focusing, ( c) meditative focusing, and ( d) defocused meditation. These were recorded on 4 consecutive days. HRV, respiration, and P300 event-related potentials (ERPs) were recorded before and after the sessions. Data were analyzed with repeated-measures analysis of variance followed by post hoc analysis. HRV showed a significant increase in low-frequency (LF) power, decrease in high-frequency (HF) power and an increase in average heart rate based on the average R-R interval after meditative focusing, compared with before. In contrast, the average heart rate decreased after defocused meditation compared with before. There was a significant increase in the P300 peak amplitude after meditative focusing and defocused meditation, with a reduction in peak latency after defocused meditation. These results suggest that after meditation with focusing, there was sympathetic arousal whereas after defocused meditation, there was a decrease in the average heart rate while participants carried out the P300 auditory oddball task sooner.

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Neurophysiological correlates of abnormal auditory processing in episodic migraine during the interictal period

Cephalalgia ◽

10.1177/0333102420951509 ◽

2020 ◽

pp. 033310242095150

Author(s):

Adrià Vilà-Balló ◽

Angela Marti-Marca ◽

Marta Torres-Ferrús ◽

Alicia Alpuente ◽

Victor José Gallardo ◽

...

Keyword(s):

Time Course ◽

Phase Synchronization ◽

Spectral Power ◽

Event Related Potentials ◽

Episodic Migraine ◽

Oscillatory Activity ◽

Oddball Paradigm ◽

Main Task ◽

Time Frequency ◽

Related Potentials

Background The characteristics of the hypersensitivity to auditory stimuli during the interictal period in episodic migraine are discussed. The combined use of event-related potentials, time-frequency power and phase-synchronization can provide relevant information about the time-course of sensory-attentional processing in migraine and its underlying mechanisms. Objective The aim of this nested case-control study was to examine these processes in young, female, episodic migraine patients interictally and compare them to controls using an active auditory oddball task. Method We recorded, using 20 channels, the electrophysiological brain activity of 21 women with episodic migraine without aura and 21 healthy matched controls without family history of migraine, during a novelty oddball paradigm. We collected sociodemographic and clinical data as well as scores related to disability, quality of life, anxiety and depression. We calculated behavioural measures including reaction times, hit rates and false alarms. Spectral power and phase-synchronization of oscillatory activity as well as event-related potentials were obtained for standard stimuli. For target and novel stimuli, event-related potentials were acquired. Results There were no significant differences at the behavioural level. In migraine patients, we found an increased phase-synchronization at the theta frequency range and a higher N1 response to standard trials. No differences were observed in spectral power. No evidence for a lack of habituation in any of the measures was seen between migraine patients and controls. The Reorienting Negativity was reduced in migraine patients as compared to controls on novel but not on target trials. Conclusion Our findings suggest that migraine patients process stimuli as more salient, seem to allocate more of their attentional resources to their surrounding environment, and have less available resources to reorient attention back to the main task.

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Frequency Sensitivity of Neural Responses to English Verb Argument Structure Violations

Collabra Psychology ◽

10.1525/collabra.87 ◽

2018 ◽

Vol 4 (1) ◽

Author(s):

Jona Sassenhagen ◽

Ryan Blything ◽

Elena V. M. Lieven ◽

Ben Ambridge

Keyword(s):

Statistical Learning ◽

High Frequency ◽

Argument Structure ◽

Low Frequency ◽

Event Related Potentials ◽

Neural Responses ◽

Online Processing ◽

Verb Argument Structure ◽

Related Potentials ◽

Intransitive Verbs

How are verb-argument structure preferences acquired? Children typically receive very little negative evidence, raising the question of how they come to understand the restrictions on grammatical constructions. Statistical learning theories propose stochastic patterns in the input contain sufficient clues. For example, if a verb is very common, but never observed in transitive constructions, this would indicate that transitive usage of that verb is illegal. Ambridge et al. (2008) have shown that in offline grammaticality judgements of intransitive verbs used in transitive constructions, low-frequency verbs elicit higher acceptability ratings than high-frequency verbs, as predicted if relative frequency is a cue during statistical learning. Here, we investigate if the same pattern also emerges in on-line processing of English sentences. EEG was recorded while healthy adults listened to sentences featuring transitive uses of semantically matched verb pairs of differing frequencies. We replicate the finding of higher acceptabilities of transitive uses of low- vs. high-frequency intransitive verbs. Event-Related Potentials indicate a similar result: early electrophysiological signals distinguish between misuse of high- vs low-frequency verbs. This indicates online processing shows a similar sensitivity to frequency as off-line judgements, consistent with a parser that reflects an original acquisition of grammatical constructions via statistical cues. However, the nature of the observed neural responses was not of the expected, or an easily interpretable, form, motivating further work into neural correlates of online processing of syntactic constructions.

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Brain Responses to World Knowledge Violations: A Comparison of Stimulus- and Fixation-triggered Event-related Potentials and Neural Oscillations

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00731 ◽

2015 ◽

Vol 27 (5) ◽

pp. 1017-1028 ◽

Cited By ~ 15

Author(s):

Paul Metzner ◽

Titus von der Malsburg ◽

Shravan Vasishth ◽

Frank Rösler

Keyword(s):

Word Meaning ◽

Event Related Potentials ◽

Visual Presentation ◽

World Knowledge ◽

N400 Effect ◽

Brain Potentials ◽

Time Frequency ◽

Gamma Range ◽

Brain Responses ◽

Related Potentials

Recent research has shown that brain potentials time-locked to fixations in natural reading can be similar to brain potentials recorded during rapid serial visual presentation (RSVP). We attempted two replications of Hagoort, Hald, Bastiaansen, and Petersson [Hagoort, P., Hald, L., Bastiaansen, M., & Petersson, K. M. Integration of word meaning and world knowledge in language comprehension. Science, 304, 438–441, 2004] to determine whether this correspondence also holds for oscillatory brain responses. Hagoort et al. reported an N400 effect and synchronization in the theta and gamma range following world knowledge violations. Our first experiment (n = 32) used RSVP and replicated both the N400 effect in the ERPs and the power increase in the theta range in the time–frequency domain. In the second experiment (n = 49), participants read the same materials freely while their eye movements and their EEG were monitored. First fixation durations, gaze durations, and regression rates were increased, and the ERP showed an N400 effect. An analysis of time–frequency representations showed synchronization in the delta range (1–3 Hz) and desynchronization in the upper alpha range (11–13 Hz) but no theta or gamma effects. The results suggest that oscillatory EEG changes elicited by world knowledge violations are different in natural reading and RSVP. This may reflect differences in how representations are constructed and retrieved from memory in the two presentation modes.

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Monitoring Migraine Cycle Dynamics with an Easy-to-Use Electrophysiological Marker—A Pilot Study

Sensors ◽

10.3390/s18113918 ◽

2018 ◽

Vol 18 (11) ◽

pp. 3918 ◽

Cited By ~ 7

Author(s):

Goded Shahaf ◽

Pora Kuperman ◽

Yuval Bloch ◽

Shahak Yariv ◽

Yelena Granovsky

Keyword(s):

Pilot Study ◽

Stress Level ◽

Event Related Potentials ◽

Healthy Controls ◽

Preliminary Results ◽

Auditory Oddball ◽

Control Subjects ◽

Related Potentials ◽

Auditory Oddball Task ◽

The Brain

Migraine attacks can cause significant discomfort and reduced functioning for days at a time, including the pre-ictal and post-ictal periods. During the inter-ictsal period, however, migraineurs seem to function normally. It is puzzling, therefore, that event-related potentials of migraine patients often differ in the asymptomatic and inter-ictal period. Part of the electrophysiological dynamics demonstrated in the migraine cycle are attention related. In this pilot study we evaluated an easy-to-use new marker, the Brain Engagement Index (BEI), for attention monitoring during the migraine cycle. We sampled 12 migraine patients for 20 days within one calendar month. Each session consisted of subjects’ reports of stress level and migraine-related symptoms, and a 5 min EEG recording, with a 2-electrode EEG device, during an auditory oddball task. The first minute of the EEG sample was analyzed. Repetitive samples were also obtained from 10 healthy controls. The brain engagement index increased significantly during the pre-ictal (p ≈ 0.001) and the ictal (p ≈ 0.020) periods compared with the inter-ictal period. No difference was observed between the pre-ictal and ictal periods. Control subjects demonstrated intermediate Brain Engagement Index values, that is, higher than inter-ictal, yet lower than pre-ictal. Our preliminary results demonstrate the potential advantage of the use of a simple EEG system for improved prediction of migraine attacks. Further study is required to evaluate the efficacy of the Brain Engagement Index in monitoring the migraine cycle and the possible effects of interventions.

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