Event-related Electroencephalography Research Articles

Altered pattern of theta and gamma oscillation to visual stimuli in patients with postconcussion syndrome.

Although many patients with mild traumatic brain injury (mTBI) suffer from postconcussional syndrome (PCS) including abnormal emotional responses, most conventional imaging studies fail to detect any causative brain lesion. We hypothesized that event-related electroencephalography (EEG) recordings with time-frequency analysis would show a distinguishable pattern in patients with mTBI with PCS compared with normal healthy controls. EEG signals were collected from a total of 18 subjects: eight patients with mTBI with PCS and 10 healthy control subjects. The signals were recorded while the subjects were presented with affective visual stimuli, including neutral, pleasant, and unpleasant emotional cues. Event-related spectral perturbation analysis was performed to calculate frontal midline theta activity and posterior midline gamma activity, followed by statistical analysis to identify whether patients with mTBI with PCS have distinct patterns of theta or gamma oscillations in response to affective stimuli. Compared with the healthy control group, patients with mTBI with PCS did not show a significant increase in the power of frontal theta activity in response to the pleasant stimuli, indicating less susceptibility toward pleasant cues. Moreover, the patient group showed attenuated gamma oscillatory activity, with no clear alteration in gamma oscillations in response to either pleasant or unpleasant cues. This study demonstrates that patients with mTBI with PCS exhibited altered patterns of oscillatory activities in the theta and gamma bands in response to affective visual stimuli compared with the normal control group. The current finding implicates that these distinguishable patterns of brain oscillation may represent the mechanism behind various psychiatric symptoms in patients with mTBI.NEW & NOTEWORTHY Patients with mild traumatic brain injury (mTBI) with postconcussional syndrome (PCS) exhibited altered patterns of changes in oscillatory activities in the theta and gamma bands in response to visual affective stimuli. Distinguishable patterns of brain oscillation may represent the mechanism behind various psychiatric symptoms in patients with mTBI.

Beta tACS of varying intensities differentially affect resting-state and movement-related M1-M1 connectivity.

Due to the interconnected nature of the brain, changes in one region are likely to affect other structurally and functionally connected regions. Emerging evidence indicates that single-site transcranial alternating current stimulation (tACS) can modulate functional connectivity between stimulated and interconnected unstimulated brain regions. However, our understanding of the network response to tACS is incomplete. Here, we investigated the effect of beta tACS of different intensities on phase-based connectivity between the left and right primary motor cortices in 21 healthy young adults (13 female; mean age 24.30 ± 4.84 years). Participants underwent four sessions of 20 min of 20 Hz tACS of varying intensities (sham, 0.5 mA, 1.0 mA, or 1.5 mA) applied to the left primary motor cortex at rest. We recorded resting-state and event-related electroencephalography (EEG) before and after tACS, analyzing changes in sensorimotor beta (13-30 Hz) imaginary coherence (ImCoh), an index of functional connectivity. Event-related EEG captured movement-related beta activity as participants performed self-paced button presses using their right index finger. For resting-state connectivity, we observed intensity-dependent changes in beta ImCoh: sham and 0.5 mA stimulation resulted in an increase in beta ImCoh, while 1.0 mA and 1.5 mA stimulation decreased beta ImCoh. For event-related connectivity, 1.5 mA stimulation decreased broadband ImCoh (4-90 Hz) during movement execution. None of the other stimulation intensities significantly modulated event-related ImCoh during movement preparation, execution, or termination. Interestingly, changes in ImCoh during movement preparation following 1.0 mA and 1.5 mA stimulation were significantly associated with participants' pre-tACS peak beta frequency, suggesting that the alignment of stimulation frequency and peak beta frequency affected the extent of neuromodulation. Collectively, these results suggest that beta tACS applied to a single site influences connectivity within the motor network in a manner that depends on the intensity and frequency of stimulation. These findings have significant implications for both research and clinical applications.

Dysfunction of Emotion Regulation in Mild Cognitive Impairment Individuals Combined With Depressive Disorder: A Neural Mechanism Study.

Depression increases the risk of progression from mild cognitive impairment (MCI) to dementia, where impaired emotion regulation is a core symptom of depression. However, the neural mechanisms underlying the decreased emotion regulation in individuals with MCI combined with depressive symptoms are not precise. We assessed the behavioral performance by emotion regulation tasks and recorded event-related electroencephalography (EEG) signals related to emotion regulation tasks simultaneously. EEG analysis, including event-related potential (ERP), event-related spectral perturbation (ERSP), functional connectivity and graph theory, was used to compare the difference between MCI individuals and MCI depressed individuals in behavioral performance, the late positive potential (LPP) amplitudes, neural oscillations and brain networks during the processing of emotional stimuli. We found that MCI depressed individuals have negative preferences and are prone to allocate more attentional resources to negative stimuli. Results suggested that theta and alpha oscillations activity is increased, and gamma oscillations activity is decreased during negative stimulus processing in MCI depressed individuals, thus indicating that the decreased emotion regulation in MCI depressed individuals may be associated with enhanced low-frequency and decreased high-frequency oscillations activity. Functional connectivity analysis revealed a decrease in functional connectivity in the left cerebral hemisphere of the alpha band and an increase in functional connectivity in the right cerebral hemisphere of the alpha band in MCI depressed individuals. Graph theory analysis suggested that global network metrics, including clustering coefficients and disassortative, decreased, while nodal and modular network metrics regarding local nodal efficiency, degree centrality, and betweenness centrality were significantly increased in the frontal lobe and decreased in the parieto-occipital lobe, which was observed in the alpha band, further suggesting that abnormal alpha band network connectivity may be a potential marker of depressive symptoms. Correlational analyses showed that depressive symptoms were closely related to emotion regulation, power oscillations and functional connectivity. In conclusion, the dominant processing of negative stimuli, the increased low-frequency oscillations activity and decreased high-frequency activity, so as the decrease in top-down information processing in the frontal parieto-occipital lobe, results in the abnormality of alpha-band network connectivity. It is suggested that these factors, in turn, contribute to the declined ability of MCI depressed individuals in emotion regulation.

Behavioural and neurophysiological differences in working memory function of depressed patients and healthy controls

ObjectiveMajor depressive disorder (MDD) is associated with deficits in working memory. Several cognitive subprocesses interact to produce working memory, including attention, encoding, maintenance and manipulation. We sought to clarify the contribution of functional deficits in these subprocesses in MDD by varying cognitive load during a working memory task. Methods41 depressed participants and 41 age and gender-matched healthy controls performed the n-back working memory task at three levels of difficulty (0-, 1-, and 2-back) in a pregistered study. We assessed response times, accuracy, and event-related electroencephalography (EEG), including P2 and P3 amplitudes, and frontal theta power (4–8 Hz). ResultsMDD participants had prolonged response times and more positive frontal P3 amplitudes (i.e., Fz) relative to controls, mainly in the most difficult 2-back condition. Working memory accuracy, P2 amplitudes and frontal theta event-related synchronisation did not differ between groups at any level of task difficulty. ConclusionsDepression is associated with generalized psychomotor slowing of working memory processes, and may involve compensatory hyperactivity in frontal and parietal regions. SignificanceThese findings provide insights into MDD working memory deficits, indicating that depressed individuals dedicate greater levels of cortical processing and cognitive resources to achieve comparable working memory performance to controls.

The interplay between emotion, cognition and information recall from websites with relevant and irrelevant images: A Neuro-IS study

Websites are increasingly used for information dissemination and web sites can include cues such as images that stimulate emotional responses in users and aid recall of information that can be utilized in decision making. However, these images may be more or less relevant in the context of the information provided. In such cases there is likely to be a complex interplay between users' emotional and cognitive responses and the degree of information recall. This study used event-related electroencephalography (EEG) to shed light on these inter-relationships. Images providing emotional cues influenced emotions and EEG responses and these responses were in turn related to the degree of information recall. Importantly, the study shows that the neural correlates of emotion vary depending on whether the emotion-inducing image is relevant to the information provided or not and that these correlates are significantly related to recall.

Numerical encoding in early visual cortex

The ability to estimate numerosity in a visual array arose early in evolution, develops early in human development, and is correlated with mathematical ability. Previous work with visually presented arrays indicates that the intraparietal sulcus (IPS) represents number. However, it is not clear if the number signal originates in IPS or is propagated from earlier visual areas. Previous work from our group has demonstrated a rapidly instantiated representation of number in low-level regions of visual cortex using the high temporal resolution of event-related electro-encephalography (EEG). Here, we use a rapid event-related functional magnetic resonance imaging (fMRI) paradigm and find convergent evidence for a number signal in low-level visual cortex (areas V1, V2, and V3). Employing a stringent set of stimulus controls, we demonstrate that this signal cannot be explained by the total extent of the array, the density of the items in the array, the aggregate visual area of the items, the size of individual items, the proportion of the array covered by items, nor the overall scale of the array and items. Our findings thus provide strong support for the hypothesis that number is rapidly and directly encoded early in the visual processing stream.

FUNCTIONAL MARKERS FOR CEREBRAL NOREPINEPHRINE DEFICIENCY IN ALZHEIMER’S DISEASE

The locus coeruleus (LC) as the only source for norepinephrine (NE) in the human brain shows early degeneration in Alzheimer’s disease (AD). The LC-NE system is involved in attentional processes and different behavioral and functional markers (e.g. evoked EEG potentials, BOLD responses, pupillary dilatation) have been identified as potential markers for LC-NE-functionality. Here, we assessed whether these markers are characteristically altered in AD, thus providing potential surrogate markers for interventional trials targeting the LC-NE-system. We aim at including patients (planned: n=30) with cerebrospinal fluid-biomarker evidence for AD and age-matched healthy controls (planned: n=30). We obtain reaction times and accuracy, event-related electroencephalography (EEG) potentials (P300b), task-related pupil dilation and event-related blood oxygen level dependent (BOLD) responses in a stimulus detection task (Oddball-paradigm). Additionally, structural magnetic resonance imaging (MRI) with neuromelanine-sensitive sequences is applied to determine a volumetric measure for the LC. Here, we present preliminary results for 15 subjects with AD and 25 control subjects. On behavioral level AD patients had longer reaction times compared to the control group while accuracies were similar. In controls, the Oddball-paradigm induced a bilateral frontoparietal BOLD response with a strong response in the dorsal pons (LC region). In AD patients the cortical response was less extended and the dorsal pontine response was decreased. The amplitudes of the P300b and the pupil response were reduced in AD patients. Unexpectedly, the P300b in AD subjects had a shorter latency compared to the controls. In pupillometric data, the latency was slightly longer in AD patients. In structural MRI larger LC volumes were observed for the left LC in the control group compared to AD subjects. Our preliminary results show alterations in behavioral and functional parameters in a signal detection task that are consistent with hypothesis (exception: shorter latency of P300b in AD patients). Our results demand confirmation in a larger sample and a demonstration that the parameters are sensitive to pharmacological manipulations of the NE systems. We suggest that these parameters might be suitable surrogate markers for pharmacological interventions targeting the LC-NE-system in AD.

Neural Alterations in Acquired Age-Related Hearing Loss.

Hearing loss is one of the most prevalent chronic health conditions in older adults. Growing evidence suggests that hearing loss is associated with reduced cognitive functioning and incident dementia. In this mini-review, we briefly examine literature on anatomical and functional alterations in the brains of adults with acquired age-associated hearing loss, which may underlie the cognitive consequences observed in this population, focusing on studies that have used structural and functional magnetic resonance imaging, diffusion tensor imaging, and event-related electroencephalography. We discuss structural and functional alterations observed in the temporal and frontal cortices and the limbic system. These neural alterations are discussed in the context of common cause, information-degradation, and sensory-deprivation hypotheses, and we suggest possible rehabilitation strategies. Although, we are beginning to learn more about changes in neural architecture and functionality related to age-associated hearing loss, much work remains to be done. Understanding the neural alterations will provide objective markers for early identification of neural consequences of age-associated hearing loss and for evaluating benefits of intervention approaches.

Implicit perceptual memory modulates early visual processing of ambiguous images.

The way we perceive the present visual environment is influenced by past visual experiences. Here we investigated the neural basis of such experience dependency. We repeatedly presented human observers with an ambiguous visual stimulus (structure-from-motion) that can give rise to two distinct perceptual interpretations. Past visual experience is known to influence the perception of such stimuli. We recorded fast dynamics of neural activity shortly after stimulus onset using event-related electroencephalography. The number of previous occurrences of a certain percept modulated early posterior brain activity starting as early as 50 ms after stimulus onset. This modulation developed across hundreds of percept repetitions, reflecting several minutes of accumulating perceptual experience. Importantly, there was no such modulation when the mere number of previous stimulus presentations was considered regardless of how they were perceived. This indicates that the effect depended on previous perception rather than previous visual input. The short latency and posterior scalp location of the effect suggest that perceptual history modified bottom-up stimulus processing in early visual cortex. We propose that bottom-up neural responses to a given visual presentation are shaped, in part, by feedback modulation that occurred during previous presentations, thus allowing these responses to be biased in light of previous perceptual decisions.

Reward feedback processing in children and adolescents: Medial frontal theta oscillations

We examined event-related electroencephalography (EEG) oscillations, including event-related spectral perturbations (ERSP) and intertrial coherence (ITC), to compare feedback processing during a chance-based reward vs. non-reward task in groups of 10–12-year-old (n=42), 13–14-year-old (n=34) and 15–17-year-olds (n=32). Because few, if any studies have applied these analytic methods to examine feedback processing in children or adolescents, we used a fine-grained approach that explored one half hertz by 16ms increments during feedback (no win vs. win events) in the theta (4–8Hz) frequency band. Complex wavelet frequency decomposition revealed that no win feedback was associated with enhanced theta power and phase coherence. We observed condition and age-based differences for both ERSP and ITC, with stronger effects for ITC. The transition from childhood to early adolescence (13–14yrs.) was a point of increased differentiation of ITC favoring no win vs. wins feedback and also compared to children or older adolescents, a point of heightened ITC for no win feedback (quadratic effect).

Generating predictions: Lesion evidence on the role of left inferior frontal cortex in rapid syntactic analysis

A well-documented phenomenon in event-related electroencephalography (EEG) and magnetoencephalography (MEG) studies on language processing is that syntactic violations of different types elicit negativities as early as 100 msec after the violation point. Recently, these responses have been associated with activations in or very close to sensory cortices, suggesting the involvement of basic sensory mechanisms in the detection of syntactic violations. The present study investigated whether intact auditory cortices and adjacent temporal regions are sufficient to generate early syntactic negativities in the auditory event-related potential (ERP). We tested ten clinically non-aphasic patients with left inferior frontal lesions, but intact temporal cortices in a passive auditory ERP paradigm that had reliably elicited early negativities in response to violations of subject-verb agreement and word category in the past. Subject-verb agreement violations failed to elicit early grammaticality effects in these patients, whereas a group of ten age-matched controls showed a reliable early negativity. This finding supports the idea that sensory aspects of syntactic analysis as reflected in early syntactic negativities critically depend on top-down predictions generated by the left inferior frontal cortex. In contrast, word category violations elicited a small, marginally significant early negativity both in controls and patients, suggesting an additional involvement of temporal regions in early phrase structure processing. In an additional auditory oddball experiment patients showed a regular P300, but no N2b component in response to deviant tones, indicating that their deficit in generating sensory predictions extends beyond the language domain.

A chan dietary intervention enhances executive functions and anterior cingulate activity in autism spectrum disorders: a randomized controlled trial.

Executive dysfunctions have been found to be related to repetitive/disinhibited behaviors and social deficits in autism spectrum disorders (ASDs). This study aims to investigate the potential effect of a Shaolin-medicine-based dietary modification on improving executive functions and behavioral symptoms of ASD and exploring the possible underlying neurophysiological mechanisms. Twenty-four children with ASD were randomly assigned into the experimental (receiving dietary modification for one month) and the control (no modification) groups. Each child was assessed on his/her executive functions, behavioral problems based on parental ratings, and event-related electroencephalography (EEG) activity during a response-monitoring task before and after the one month. The experimental group demonstrated significantly improved mental flexibility and inhibitory control after the diet modification, which continued to have a large effect size within the low-functioning subgroup. Such improvements coincided with positive evaluations by their parents on social communication abilities and flexible inhibitory control of daily behaviors and significantly enhanced event-related EEG activity at the rostral and subgenual anterior cingulate cortex. In contrast, the control group did not show any significant improvements. These positive outcomes of a one-month dietary modification on children with ASD have implicated its potential clinical applicability for patients with executive function deficits.

Event-related brain activity during observation of simple motor behaviour in minimally conscious state (MCS) patients

Event Abstract Back to Event Event-related brain activity during observation of simple motor behaviour in minimally conscious state (MCS) patients Julia Lechinger1*, Nicole Chwala-Schlegel1, Theresa Stemeseder1, Robert Fellinger2 and Manuel Schabus1 1 Lab for Sleep & Consciousness, Univ. of Salzburg, Austria 2 Oscillations, Brain & Thinking Laboratory, Univ. of Salzburg, Austria Estimating cognitive functioning in patients suffering from Disorders of Consciousness (DOC) by use of behavioural measures is often challenging. Therefore it can be highly desirable to identify brain correlates such as event-related electroencephalography (EEG) which can be systematically associated with specific diagnoses. EEG from 10 Vegetative State (VS) and 7 Minimally Conscious State (MCS) patients was recorded while patients were shown 2.5 sec videos displaying a right or left arm grabbing a cup and moving it towards an invisible mouth. At the same time the respective command was presented auditorily (“grab right/left and drink”). Event-related de-/synchronisation (ERD/ERS) was calculated and repeated measures ANOVAS DIAGNOSIS x HEMI were conducted for frequencies theta (4-6 Hz), alpha1 (8-10 Hz) and sensory motor rhythm (SMR, 12-15 Hz) as well as for five poststimulus 500 ms windows. First analysis showed that during watching 2.5 sec videos displaying simple motor behaviour MCS patients showed stronger parieto-occipital alpha1 ERD than VS patients [left arm movement (lARM): 500-1000 ms, F = 6.57, p < .05; right arm movement (rARM): 1500-200 0ms, contralaterally only, F = 5.43, p < .05]. Furthermore SMR ERS was stronger in MCS than VS patients at central sites [lARM:1500-2000, contralaterally stronger, F = 6.05, p < .05; rARM: 1000-1500 ms, F = 8.7, p < .05] as well as at parietal sites [lARM: 1000-1500 ms, F = 11.96, p < .01; rARM: 1000-1500, F = 6.33, p < .05]. Here MCS patients - as compared to VS patients - showed specific brain activation in the alpha and SMR frequency band indicating that they were to some extent able to understand and to mirror a simple reaching movement. Keywords: EEG, Neuropsychiatry Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Neuropsychiatric Applications Citation: Lechinger J, Chwala-Schlegel N, Stemeseder T, Fellinger R and Schabus M (2011). Event-related brain activity during observation of simple motor behaviour in minimally conscious state (MCS) patients. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00237 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: 21 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Julia Lechinger, Lab for Sleep & Consciousness, Univ. of Salzburg, Salzburg, Austria, julia.lechinger@sbg.ac.at 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 Julia Lechinger Nicole Chwala-Schlegel Theresa Stemeseder Robert Fellinger Manuel Schabus Google Julia Lechinger Nicole Chwala-Schlegel Theresa Stemeseder Robert Fellinger Manuel Schabus Google Scholar Julia Lechinger Nicole Chwala-Schlegel Theresa Stemeseder Robert Fellinger Manuel Schabus PubMed Julia Lechinger Nicole Chwala-Schlegel Theresa Stemeseder Robert Fellinger Manuel Schabus 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.

Why is that Hammer in My Coffee? A Multimodal Imaging Investigation of Contextually Based Tool Understanding

Appropriate tool–object pairing is a natural part of our lives. When preparing to stir coffee, we know that a hammer is useful for some tasks but that it is not appropriate in this behavioral context. The neural correlates of this context–tool pairing process remain unclear. In the current work, we used event-related electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to determine neural correlates for differentiating contextually correct and incorrect tool use. Subjects were shown images depicting correct (e.g., spoon used to stir coffee) or incorrect (e.g., hammer used to stir coffee) tool use. We identified distinct regional and temporal activations for identifying incorrect versus correct tool use. The posterior cingulate, insula, and superior temporal gyrus preferentially differentiated incorrect tool–object usage, while occipital, parietal, and frontal areas were active in identifying correct tool use. Source localized EEG analysis confirmed the fMRI data and showed phases of activation, where incorrect tool-use activation (0–200 ms) preceded occipitotemporal activation for correct tool use (300–400 ms). This work extends our previous findings to better identify the neural substrate for contextual evaluation of tool use, and may contribute to our understanding of neurological disorders resulting in tool-use deficits.

Language and Brain: What is Up? What is Coming Up?

The classical aphasiological model of brain/language relationships is nowadays complemented by independent results from functional neuroimaging studies using techniques such as Positron Emission Tomography, functional Magnetic Resonance Imaging, or Event-Related Electro-Encephalography and Magneto-Encephalography mapping. Although brain mapping of language is still hampered by many methodological pitfalls, these methods now appear reliable and provide a renewed description of the temporal spatial dynamics of neural ensembles subserving language functions. Moreover, neuroimaging techniques should also shed a new light on remaining difficult issues such as neural and functional plasticity in developmental or post-lesional contexts.