Event-related Brain Oscillations Research Articles

Event-related brain dynamics during mind wandering in attention-deficit/hyperactivity disorder: An experience-sampling approach

Adults with attention-deficit/hyperactivity disorder (ADHD) report increased spontaneous mind wandering (MW) compared to control adults. Since MW is associated with ADHD severity and functional impairment, elucidating the brain mechanisms underlying MW may inform new interventions targeting MW and point to neural markers to monitor their efficacy. Population-based electroencephalographic (EEG) studies suggest that weaker event-related decreases in occipital alpha power characterise periods of MW, but no study has examined event-related brain oscillations during MW in individuals with ADHD. Using an experience-sampling method, we compared adults with ADHD (N = 23) and controls (N = 25) on event-related EEG measures of power modulations and phase consistency during two tasks with high and low demands on working memory and sustained attention, and during periods of MW and task focus. Compared to controls, individuals with ADHD showed weaker alpha power decreases during high working memory demands and across sustained attention demands, weaker theta power increases and phase consistency across working memory demands and during low sustained attention demands, and weaker beta power decreases during low working memory demands. These EEG patterns suggest broadly deficient attentional and motor response processes in ADHD. During MW episodes, adults with ADHD showed weaker alpha power decreases in the sustained attention task and lower theta phase consistency in the working memory task compared to controls. These findings suggest that atypical EEG patterns thought to reflect reduced inhibition of task-irrelevant processes and inconsistent stimulus processing underlie increased MW in adults with ADHD and may be useful for future real-time monitoring of treatment effects.

Effects of transcutaneous vagus nerve stimulation (tVNS) on beta and gamma brain oscillations

Physiological and behavioral effects induced through transcutaneous vagus nerve stimulation (tVNS) are under scrutiny in a growing number of studies, yet its mechanisms of action remain poorly understood. One candidate mechanism is a modulation of γ-aminobutyric acid (GABA) transmission through tVNS. Two recent behavioral studies suggest that such a GABAergic effect might occur in a lateralized fashion, i.e., the GABA modulation might be stronger in the left than in the right brain hemisphere after tVNS applied to the left ear. Using magnetoencephalography (MEG), we tested for GABA-associated modulations in resting and event-related brain oscillations and for a lateralization of those effects in a sample of 41 healthy young adults. Our data provide substantial evidence against all hypotheses, i.e., we neither find effects of tVNS on oscillatory power nor a lateralization of effects.

Age related differences in the recognition of facial expression: Evidence from EEG event-related brain oscillations

Facial Expression (FE) recognition is a major marker of emotional ability. Behavioral studies show that FE recognition ability decreases with aging. Studying how event-related brain oscillations change with normal aging is important to better understand the underlying mechanisms of emotional processes. The aim of this study is to investigate changes in FE recognition due to normal aging using the EEG-Brain Oscillations approach.Fifteen young and fifteen elderly healthy subjects were included in the study. 15 photographs were used with 5 different FEs (angry, happy, neutral, sad, fearful). After each EEG recording session, subjects were asked to identify the FEs that were presented. Event-related delta, theta and, alpha phase-locking and frequency-band responses were analyzed.In the FE recognition part of the study, young subjects obtained better scores than the elderly subjects. There was a significant result regarding the locationXgroup comparison in the delta response; the young group had a higher delta response than the elderly group over the occipital area. There were significant locationXgroup differences in the theta and alpha phase locking values; the elderly group had higher theta and alpha phase locking values than the young group in the frontal area. Group differences were significant in the theta response and theta phase locking; the elderly individuals' theta response and phase locking values were higher compared to those of the young individuals.In elderly individuals, FE recognition impairment has been observed. It has been shown that the impairment may be characterized by decreased occipital delta responses and phase locking. This can be interpreted to mean that elderly individuals may have developed different brain dynamics as a compensating mechanism since they are not as efficient as young individuals in performing these functions.

Impairment in recognition of emotional facial expressions in Alzheimer's disease is represented by EEG theta and alpha responses.

Behavioral studies have shown that the recognition of facial expressions may be impaired in patients with Alzheimer's disease (AD). The identification and recognition of a facial expression might be represented by event-related brain oscillations. The present study aims to analyze EEG event-related oscillations and determine the electrophysiological indicators of impaired facial expression recognition in AD patients. EEGs of 30 healthy controls and 30 AD patients were recorded during their perception of three different facial expressions (angry, happy, neutral). Event-related power spectrum and phase locking were analyzed in the theta (4-7) and alpha (8-13Hz) frequency bands with the EEGLAB open toolbox. There was a significant facial Expression×Group interaction (p<0.05) for the theta power spectrum; the healthy control group had higher theta power than the AD group during the perception of angry facial expressions (p<0.05). There was a significant hemisphere difference between the two groups (p<0.05). There was a right hemisphere alpha power dominance in healthy subjects. However, AD patients did not have this alpha power asymmetry. The present study, for the first time in the literature, presents the electrophysiological indicators of impaired recognition of facial expression in AD patients. The current study could be a basis for future studies that will analyze emotional processing in different kinds of dementia patients, and this study may have provided indicators of electrophysiological correlates of behavioral problems observed in clinical practice.

Shared and Disorder-Specific Event-Related Brain Oscillatory Markers of Attentional Dysfunction in ADHD and Bipolar Disorder

Attention-deficit/hyperactivity disorder (ADHD) and bipolar disorder (BD) often present with overlapping symptoms and cognitive impairments, such as increased fluctuations in attentional performance measured by increased reaction-time variability (RTV). We previously provided initial evidence of shared and distinct event-related potential (ERP) impairments in ADHD and BD in a direct electrophysiological comparison, but no study to date has compared neural mechanisms underlying attentional impairments with finer-grained brain oscillatory markers. Here, we aimed to compare the neural underpinnings of impaired attentional processes in ADHD and BD, by examining event-related brain oscillations during a reaction-time task under slow-unrewarded baseline and fast-incentive conditions. We measured cognitive performance, ERPs and brain-oscillatory modulations of power and phase variability in 20 women with ADHD, 20 women with BD (currently euthymic) and 20 control women. Compared to controls, both ADHD and BD groups showed increased RTV in the baseline condition and increased RTV, theta phase variability and lower contingent negative variation in the fast-incentive condition. Unlike controls, neither clinical group showed an improvement from the slow-unrewarded baseline to the fast-incentive condition in attentional P3 amplitude or alpha power suppression. Most impairments did not differ between the disorders, as only an adjustment in beta suppression between conditions (lower in the ADHD group) distinguished between the clinical groups. These findings suggest shared impairments in women with ADHD and BD in cognitive and neural variability, preparatory activity and inability to adjust attention allocation and activation. These overlapping impairments may represent shared neurobiological mechanisms of attentional dysfunction in ADHD and BD, and potentially underlie common symptoms in both disorders.

Feasibility of Online Neuromodulation Using Transcranial Alternating Current Stimulation in Schizophrenia

Abnormalities in resting and event-related brain oscillations are known to be associated with cognitive deficits in schizophrenia. Transcranial alternating current stimulation (tACS) modulates these rhythms across the neuronal circuits and could have a potential therapeutic role in psychiatric disorders. In this report, we describe, for the first time, application of online tACS in a schizophrenia patient with working memory deficits. This case report supports the feasibility and potential utility of online tACS in schizophrenia, which needs further systematic research.

Infant Auditory Processing and Event-related Brain Oscillations.

Rapid auditory processing and acoustic change detection abilities play a critical role in allowing human infants to efficiently process the fine spectral and temporal changes that are characteristic of human language. These abilities lay the foundation for effective language acquisition; allowing infants to hone in on the sounds of their native language. Invasive procedures in animals and scalp-recorded potentials from human adults suggest that simultaneous, rhythmic activity (oscillations) between and within brain regions are fundamental to sensory development; determining the resolution with which incoming stimuli are parsed. At this time, little is known about oscillatory dynamics in human infant development. However, animal neurophysiology and adult EEG data provide the basis for a strong hypothesis that rapid auditory processing in infants is mediated by oscillatory synchrony in discrete frequency bands. In order to investigate this, 128-channel, high-density EEG responses of 4-month old infants to frequency change in tone pairs, presented in two rate conditions (Rapid: 70 msec ISI and Control: 300 msec ISI) were examined. To determine the frequency band and magnitude of activity, auditory evoked response averages were first co-registered with age-appropriate brain templates. Next, the principal components of the response were identified and localized using a two-dipole model of brain activity. Single-trial analysis of oscillatory power showed a robust index of frequency change processing in bursts of Theta band (3 - 8 Hz) activity in both right and left auditory cortices, with left activation more prominent in the Rapid condition. These methods have produced data that are not only some of the first reported evoked oscillations analyses in infants, but are also, importantly, the product of a well-established method of recording and analyzing clean, meticulously collected, infant EEG and ERPs. In this article, we describe our method for infant EEG net application, recording, dynamic brain response analysis, and representative results.

Infant Auditory Processing and Event-related Brain Oscillations

Rapid auditory processing and acoustic change detection abilities play a critical role in allowing human infants to efficiently process the fine spectral and temporal changes that are characteristic of human language. These abilities lay the foundation for effective language acquisition; allowing infants to hone in on the sounds of their native language. Invasive procedures in animals and scalp-recorded potentials from human adults suggest that simultaneous, rhythmic activity (oscillations) between and within brain regions are fundamental to sensory development; determining the resolution with which incoming stimuli are parsed. At this time, little is known about oscillatory dynamics in human infant development. However, animal neurophysiology and adult EEG data provide the basis for a strong hypothesis that rapid auditory processing in infants is mediated by oscillatory synchrony in discrete frequency bands. In order to investigate this, 128-channel, high-density EEG responses of 4-month old infants to frequency change in tone pairs, presented in two rate conditions (Rapid: 70 msec ISI and Control: 300 msec ISI) were examined. To determine the frequency band and magnitude of activity, auditory evoked response averages were first co-registered with age-appropriate brain templates. Next, the principal components of the response were identified and localized using a two-dipole model of brain activity. Single-trial analysis of oscillatory power showed a robust index of frequency change processing in bursts of Theta band (3 - 8 Hz) activity in both right and left auditory cortices, with left activation more prominent in the Rapid condition. These methods have produced data that are not only some of the first reported evoked oscillations analyses in infants, but are also, importantly, the product of a well-established method of recording and analyzing clean, meticulously collected, infant EEG and ERPs. In this article, we describe our method for infant EEG net application, recording, dynamic brain response analysis, and representative results.

Impairment of oscillatory activity in survivors of severe sepsis: a magnetoencephalography study

A number of studies suggest that the clinical manifestation of neurological deficits results from pathologically synchronized neuronal oscillations and altered oscillatory coupling in the brain. For example, aberrant neuronal synchronization was already shown in patients diagnosed with liver cirrhosis. Currently, more and more evidence has been given that former critical care patients, especially survivors of severe sepsis, endure long-lasting cognitive impairments. Sepsis survivors are known to frequently develop an encephalopathy, which is commonly considered as reversible, but profound knowledge is still lacking. In this study, 25 cirrhotic patients, 23 normal healthy controls and 26 sepsis survivors were included. Sepsis survivors were included either shortly, 6 or 12 months after ICU discharge. In these three groups, magnetoencephalography (MEG) data were collected at rest and during a visual task employing repetitive flicker stimulation. Resting MEG and evoked responses were analyzed. While normal, healthy controls showed the highest resting frequency, we observed a lower frequency in cirrhotic patients and sepsis survivors. In sepsis survivors, the lowest resting frequency was found at T0. Moreover, cirrhotic patients and sepsis survivors were not able to dynamically adapt to the visual flickering stimulation, i.e. coupling to flickering stimulation was significantly lower in the two patient groups in comparison to normal, healthy controls. Interestingly, coupling improved with the time after ICU discharge in sepsis survivors. These results indicate abnormal ongoing and event-related brain oscillations in HE patients and also in sepsis survivors. The findings analysing coupling to visual stimulation in particular suggest a lack of local cortical synchronization.

Semantic priming increases left hemisphere theta power and intertrial phase synchrony.

Information is stored in distributed cortical networks, but it is unclear how distributed stores are synthesized into a unified percept. Activation of local circuits in the gamma range (30 < < 80 Hz), and distributed stores in the low theta range (3-5 Hz) may underlie perceptual binding. Words have a crucial role in semantic memory. Within memory, the activation of distributed semantic stores is facilitated by conceptually related previous items, termed semantic priming. We sought to detect event-related brain oscillations (EROs) sensitive to semantic activation and priming. Here, we show that low theta evoked power and intertrial phase locking (4-5 Hz) from 250-350 msec over left hemisphere language areas was greater to related than to unrelated words. Theta band event-related oscillations over left hemisphere language areas may provide a brain signature for semantic activation across distributed stores being facilitated by semantic priming.

Genome‐wide association study of theta band event‐related oscillations identifies serotonin receptor gene HTR7 influencing risk of alcohol dependence

Event-related brain oscillations (EROs) represent highly heritable neuroelectrical correlates of human perception and cognitive performance that exhibit marked deficits in patients with various psychiatric disorders. We report the results of the first genome-wide association study (GWAS) of an ERO endophenotype-frontal theta ERO evoked by visual oddball targets during P300 response in 1,064 unrelated individuals drawn from a study of alcohol dependence. Forty-two SNPs of the Illumina HumanHap 1 M microarray were selected from the theta ERO GWAS for replication in family-based samples (N = 1,095), with four markers revealing nominally significant association. The most significant marker from the two-stage study is rs4907240 located within ARID protein 5A gene (ARID5A) on chromosome 2q11 (unadjusted, Fisher's combined P = 3.68 × 10⁻⁶). However, the most intriguing association to emerge is with rs7916403 in serotonin receptor gene HTR7 on chromosome 10q23 (combined P = 1.53 × 10⁻⁴), implicating the serotonergic system in the neurophysiological underpinnings of theta EROs. Moreover, promising SNPs were tested for association with diagnoses of alcohol dependence (DSM-IV), revealing a significant relationship with the HTR7 polymorphism among GWAS case-controls (P = 0.008). Significant recessive genetic effects were also detected for alcohol dependence in both case-control and family-based samples (P = 0.031 and 0.042, respectively), with the HTR7 risk allele corresponding to theta ERO reductions among homozygotes. These results suggest a role of the serotonergic system in the biological basis of alcohol dependence and underscore the utility of analyzing brain oscillations as a powerful approach to understanding complex genetic psychiatric disorders.

Event-Related Brain Oscillations

Neuroelectric oscillations provide important tools to study information processing in the brain. In this paper, major concepts and advantages of event-related oscillations (EROs) are considered, with a focus on their relevance for developmental research. Findings from previous studies in passive and oddball conditions are summarized to demonstrate that the age-dependent power decrease of theta (4–7 Hz) and alpha (8–14 Hz) EROs is accompanied by an increase in the synchronization of these oscillations. New data are presented to test whether this dissociation depends on processing demands in a frequency-specific manner. Results from an auditory serial learning task with working memory activation performed by 70 subjects (children from 6 to 10 years of age and adults) indicate that this effect was observed for theta and slow alpha oscillations, whereas an age-dependent decrease in event-related phase synchronization was found for fast alpha oscillations. It is concluded that phase synchronization of only the major theta and alpha EROs may reflect the neurobiological maturation of neural networks involved in perception. Phase synchronization of EROs, however, especially from faster frequency bands, essentially depends on the mode of network involvement and functional competence, which is associated with cognitive processing abilities or strategies in the course of development.

Alpha Brain Oscillations and Inhibitory Control

A major challenge for developmental cognitive neuroscience is to understand how changes in cognitive functions related to aging are associated with changes in the neuronal information processing architecture. Previous studies on EEG event-related brain oscillations suggest functional changes in alpha-bands with age during sensory and memory tasks. Specifically, the topographical distribution of both single-trial lower and upper alpha magnitude and the corresponding phase coherence is altered in elderly persons. Thus, alpha oscillations, associated not only with sensory, but also with sensorimotor functions, may be altered with age. Compensatory mechanisms, possibly reflected in increased frontal alpha synchronization, may thereby be of profound relevance. The present study investigates age-related differences in the modulation of alpha oscillatory activity related to sensory and sensorimotor functions, including response preparation, execution, and inhibition. EEG was recorded while 10 young and 10 elderly persons performed a visual evoked potential (VEP), a cued stimulus response (S-R), and a cued visual Go&amp;#47;NoGo task. Early event-related synchronization (ERS, 0&amp;#8211;250 ms) and late event-related desynchronization (ERD, 200&amp;#8211;600 ms) of single-trial lower and upper alpha was analyzed using poststimulus amplitude enhancement and intertrial phase coherence measures. The results show comparable modulations of lower (8&amp;#8211;10 Hz) and upper (10&amp;#8211;15 Hz) alpha activity in young and elderly related to the sensory and different forms of motor response processing. Specifically, reduced early lower alpha ERS as well as late upper alpha ERD at central locations characterized response inhibition processing in both age groups. We discuss the counterintuitive hypothesis that reduced efficacy of some basal neural inhibitory mechanisms enables older observers to perform better than or comparable to younger observers on some visual tasks, and conclude that alterations in alpha oscillatory networks with age may depend on the stimuli applied.

Event-Related Oscillations (ERO) and Event-Related Potentials (ERP) in Emotional Face Recognition

The study aims to explore the significance of event-related potentials (ERPs) and event-related brain oscillations (EROs) (delta, theta, and alpha power) in response to emotional face during 180–250 poststimulus time interval. Twenty-one adults looked at emotional (sad, happy, fearful) or neutral faces. The results demonstrated that the emotional face elicited a negative peak at approximately 230 ms (N230). Moreover EEG measures showed that motivational significance of face (stimulus type) can modulate the amplitude of EEG, especially for theta and delta. Regression analysis showed that theta oscillations mainly effect as oscillation activity at the N2 latency. Thus, this frequency band variation could represent a complex set of cognitive processes, whereby selective attention becomes focused on an emotional relevant stimulus.

Event-related brain oscillations associated with color-word interference

Event Abstract Back to Event Event-related brain oscillations associated with color-word interference Mehmet Ergen1*, S. Saban2, E. Kirmizi-Alsan1, Zübeyir Bayraktaroglu1, A. Uslu1, H. Gürvit1 and T. Demiralp1 1 Istanbul University, Turkey 2 Yeditepe University, Turkey Stroop color-word test requires subjects to read (semantic processing) a color word printed in a different ink color. The interference between word meaning and ink color slows down the reactions to incongruent stimuli. EEG was recorded from 23 subjects during a computerized version of Stroop test. The longer reaction time for incongruent condition was replicated. N4 potential was found to be more negative for incongruent condition, which is also in line with the previous findings. The wavelet transforms of the averaged ERP and the single trials were computed to investigate the amplitudes of the evoked (phase-locked) and total (phase-locked + non-phase-locked) oscillatory responses. Evoked delta (250-600 ms) was larger in response to congruent trial (p<0.01), which can be interpreted as somewhat coherent with our earlier studies on oddball experiments. Since the delta response has been related with stimulus evaluation and decision making, a larger delta response for congruent condition which involves a relatively simpler decision process was predicted. The total theta activity (300-700 ms) was significantly increased incongruent trials (p=0.05), and this effect was more prominent over fronto-central region (p<0.05). The late timing and frontal scalp distribution of theta suggest that it could be related to resolution of the conflict in response production stage, due to color-word interference. The evoked alpha response (100-200 ms) in incongruent trials was higher with trend level significance, and this finding leads to the reconsideration of the assumption based on the time-domain analyses that the processes dealing with the color-word interference start around 450 ms. Finally, the results on time-frequency plane, allowed further characterization of the cognitive processes during resolution of Stroop interference. Conference: 10th International Conference on Cognitive Neuroscience, Bodrum, Turkey, 1 Sep - 5 Sep, 2008. Presentation Type: Oral Presentation Topic: Decision Making and Response Selection Citation: Ergen M, Saban S, Kirmizi-Alsan E, Bayraktaroglu Z, Uslu A, Gürvit H and Demiralp T (2008). Event-related brain oscillations associated with color-word interference. Conference Abstract: 10th International Conference on Cognitive Neuroscience. doi: 10.3389/conf.neuro.09.2009.01.181 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: 08 Dec 2008; Published Online: 08 Dec 2008. * Correspondence: Mehmet Ergen, Istanbul University, Istanbul, Turkey, mehmet.ergen@gmail.com 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 Mehmet Ergen S. Saban E. Kirmizi-Alsan Zübeyir Bayraktaroglu A. Uslu H. Gürvit T. Demiralp Google Mehmet Ergen S. Saban E. Kirmizi-Alsan Zübeyir Bayraktaroglu A. Uslu H. Gürvit T. Demiralp Google Scholar Mehmet Ergen S. Saban E. Kirmizi-Alsan Zübeyir Bayraktaroglu A. Uslu H. Gürvit T. Demiralp PubMed Mehmet Ergen S. Saban E. Kirmizi-Alsan Zübeyir Bayraktaroglu A. Uslu H. Gürvit T. Demiralp 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.

Event‐related oscillations (EROs) and event‐related potentials (ERPs) comparison in facial expression recognition

The study aims to explore the significance of event-related potentials (ERPs) and event-related brain oscillations (EROs) (delta, theta, alpha, beta, gamma power) in response to emotional (fear, happiness, sadness) when compared with neutral faces during 180-250 post-stimulus time interval. The ERP results demonstrated that the emotional face elicited a negative peak at approximately 230 ms (N2). Moreover, EEG measures showed that motivational significance of face (emotional vs. neutral) could modulate the amplitude of EROs, but only for some frequency bands (i.e. theta and gamma bands). In a second phase, we considered the resemblance of the two EEG measures by a regression analysis. It revealed that theta and gamma oscillations mainly effect as oscillation activity at the N2 latency. Finally, a posterior increased power of theta was found for emotional faces.