Dry electrodes are becoming popular for both lab‐based and consumer‐level electrophysiological‐recording technologies because they better afford the ability to move traditional lab‐based research ...into the real world. It is unclear, however, how dry electrodes compare in data quality to traditional electrodes. The current study compared three EEG electrode types: (a) passive‐wet electrodes with no onboard amplification, (b) actively amplified, wet electrodes with moderate impedance levels, and low impedance levels, and (c) active‐dry electrodes with very high impedance. Participants completed a classic P3 auditory oddball task to elicit characteristic EEG signatures and event‐related potentials (ERPs). Across the three electrode types, we compared single‐trial noise, average ERPs, scalp topographies, ERP noise, and ERP statistical power as a function of number of trials. We extended past work showing active electrodes’ insensitivity to moderate levels of interelectrode impedance when compared to passive electrodes in the same amplifier. Importantly, the new dry electrode system could reliably measure EEG spectra and ERP components comparable to traditional electrode types. As expected, however, dry active electrodes with very high interelectrode impedance exhibited marked increases in single‐trial and average noise levels, which decreased statistical power, requiring more trials to detect significant effects. This power decrease must be considered as a trade‐off with the ease of application and long‐term use. The current results help set constraints on experimental design with novel dry electrodes, and provide important evidence needed to measure brain activity in novel settings and situations.
Aerobic exercise has been identified as an effective strategy for transiently enhancing inhibitory control, an ability to suppress irrelevant distractors while focusing on relevant information in ...facilitating the implementation of goal‐directed behavior. The purpose of this study was to employ a go/no‐go version of the redundant‐target task and event‐related potential to further determine whether inhibitory control at the perceptual and response levels as well as their underlying processing capacity and neuroelectric alterations are differentially affected by a single bout of aerobic exercise. Twenty‐seven young adults completed the redundant‐target task while electroencephalogram was recorded before and after one 20‐min bout of moderate‐intensity aerobic exercise and a sitting control condition on separate days in counterbalanced order. Although behavioral outcomes of mean‐level performance did not differ between intervention conditions, time‐related decreases in processing capacity for the faster responses were only observed following rest. Aerobic exercise resulted in maintained P3b amplitude from pretest to posttest for all trial types while decreased P3b amplitude from pretest to posttest during single‐target and redundant‐target trials was observed following rest. Further, the time‐related changes in P3b amplitude were positively correlated with improvements in task performance following exercise. These findings suggest that a short bout of aerobic exercise selectively counteracts the time‐related decrements in processing capacity as well as neuroelectric processing of attention and conflict suppression that contribute to behavioral outcomes of inhibitory control.
A single bout of aerobic exercise selectively counteracts time‐related decrements in general information processing efficiency measured by system factorial technology (SFT) as well as neuroelectric correlates (i.e., P3‐ERP) of conflict suppression but not response inhibition when both these processes are required in a novel inhibitory control task. Further, P3b amplitude and task performance changes after exercise are positively correlated. The significance of these findings lies in the identification of conflict suppression as the isolated sub‐process that can transiently benefit from exercise.
Response inhibition deficits in schizophrenia (SZ) are accompanied by reduced neural activities using event‐related potential (ERP) measurements. However, it remains unclear whether the reduction in ...inhibition‐related ERPs in SZ is contingent upon prepotent motor tendencies. This study aimed to examine the relationship between ERP markers of prepotent motor activity (lateralised readiness potential, LRP) and response inhibition (P3) by collecting behavioural and EEG data from healthy control (HC) subjects and SZ patients during a modified Go/No‐Go task. A trial‐averaged analysis revealed that SZ patients made more commission errors in No‐Go trials compared with HC subjects, although there was no significant difference in the inhibition‐related P3 effect (i.e. larger P3 amplitudes in No‐Go compared with Go trials) between the two groups. Subsequently, No‐Go trials were sorted and median‐split into bins of stronger and weaker motor tendencies. Both HC and SZ participants made more commission errors when faced with stronger motor tendencies. The LRP‐sorted P3 data indicated that HC subjects exhibited larger P3 effects in response to stronger motor tendencies, whereas this trial‐by‐trial association between P3 and motor tendencies was absent in SZ patients. Furthermore, SZ patients displayed diminished P3 effects in No‐Go trials with stronger motor tendencies but not in trials with weaker motor tendencies, relative to HC subjects. Taken together, these findings suggest that SZ patients are unable to dynamically adjust inhibition‐related neural activities in response to changing inhibitory control demands and emphasise the importance of considering prepotent motor activity when investigating the neural mechanisms underlying response inhibition deficits in SZ.
Background
Electroencephalography (EEG) and related measures have a long and productive history in child psychopathology research and are currently experiencing a renaissance in interest, ...particularly for use as putative biomarkers.
Method and Scope
First, the recent history leading to the use of EEG measures as endophenotypes and biomarkers for disease and treatment response are reviewed. Two key controversies within the area of noninvasive human electrophysiology research are discussed, and problems that currently either function as barriers or provide gateways to progress. First, the differences between the main types of EEG measurements (event‐related potentials, quantitative EEG, and time–frequency measures) and how they can contribute collectively to better understanding of cortical dynamics underlying cognition and behavior are highlighted. Second, we focus on the ongoing shift in analytic focus to specific cortical sources and source networks whose dynamics are relevant to the clinical and experimental focus of the study, and the effective increase in source signal‐to‐noise ratio (SNR) that may be obtained in the process.
Conclusions
Understanding of these issues informs any discussion of current trends in EEG research. We highlight possible ways to evolve our understanding of brain dynamics beyond the apparent contradictions in understanding and modeling EEG activity highlighted by these controversies. Finally, we summarize some promising future directions of EEG biomarker research in child psychopathology.
In the face of unpredictable threat, rapid processing of external events and behavioral mobilization through early psychophysiological responses are crucial for survival. While unpredictable threat ...generally enhances early processing, it would seem adaptive to particularly increase sensitivity for unexpected events as they may signal danger. To examine this possibility, n = 77 participants performed an auditory oddball paradigm and received unpredictable shocks in threat but not in safe contexts while a stream of frequent (standard) and infrequent (deviant) tones was presented. We assessed event‐related potentials (ERP), heart period (HP), and time‐lagged within‐subject correlations of single‐trial EEG and HP (cardio‐EEG covariance tracing, CECT) time‐locked to the tones. N1 and P2 ERP amplitudes were generally enhanced under threat. The P3 amplitude was enhanced to deviants versus standards and this effect was reduced in the threat condition. Regarding HP, both threat versus safe and unexpected versus expected tones led to stronger cardiac acceleration, suggesting separate effects of threat and stimulus expectancy on HP. Finally, CECTs revealed two correlation clusters, indicating that single‐trial EEG magnitudes in the N1/P2 and P3 time‐windows predicted subsequent cardiac acceleration. The current results show that an unpredictable threat context enhances N1 and P2 amplitudes and cardiac acceleration to benign auditory stimuli. They further suggest separable cortical correlates of different effects on cardiac activity: an early N1/P2 correlate associated with threat‐effects on HP and a later P3 correlate associated with expectedness‐effects. Finally, the results indicate that unpredictable threat attenuates rather than enhances the processing of unexpected benign events during the P3 latency.
Our study shows how the brain may regulate cardiac responses during threat anticipation and processing of unexpected stimuli. Early tone‐evoked frontomedial N1 and P2 responses and subsequent cardiac acceleration are not only enhanced during unpredictable threat but are also functionally coupled as indicated by time‐lagged within‐subject correlations emerging during threat and safety. In addition, P3 and heart period, both sensitive to stimulus expectedness during threat and safe contexts, also appear functionally coupled.
The current study examined patterns of event‐related potential (ERP) responses during a face processing task in groups of preschoolers uniquely impacted by autism spectrum disorder (ASD), including ...(1) children with ASD; (2) children with fragile X syndrome (FXS); (3) children with familial risk for ASD, but without a diagnosis (i.e., ASIBs); and (4) a low‐risk control (LRC) group. Children with FXS have a high incidence of ASD diagnoses, but there have been no studies of the ERP response to faces in children with FXS and little work focused on children with ASD who have cognitive impairment. The current study examined children's ERP responses to faces and houses in four groups: LRC (N = 28, age = 5.2 years), ASIB (N = 23, age = 5.5 years), FXS (N = 19, age = 5.82 years), and ASD (N = 23, age = 5.5 years). The FXS and ASD groups were characterized by the presence of cognitive impairment. Pictures of upright and inverted faces and houses were presented while recording EEG with a 128‐channel system. The N170 occurred at about 200 ms post stimulus onset, was largest on the posterior‐lateral electrodes, and was larger for faces than houses. The P1 and N170 ERP components were larger for the FXS group than for the other three groups. The N170 ERP amplitude for the ASD and ASIB groups was smaller than both the LRC and FXS groups, and the LRC and FXS groups had the largest N170 responses on the right side. No difference was found in N170 latency between groups. The similarity of the ASD and ASIB responses suggest a common genetic or environmental origin of the reduced response. Although children with FXS have a high incidence of ASD outcomes, they differed from ASD and ASIB children in this study. Specifically, the children with FXS were hyperresponsive to all stimulus types while the ASD and ASIB groups showed attenuated responses for specific stimuli.
Lay Summary
Children with fragile X syndrome (FXS) show enhanced brain responses to visual stimuli compared to low‐risk controls, whereas children with autism spectrum disorder (ASD), and non‐ASD siblings of children with ASD (ASIB) show attenuated responses. The similarity of the ASD and ASIB responses suggest a common genetic or environmental origin of the reduced response. The enhanced event‐related‐potential (ERP) in EEG in children with FXS, and in the same group of children when tested as infants, suggests a hyperresponsivity to social and nonsocial stimuli in children with FXS.
The processing of threat‐related emotional body language (EBL) has been shown to engage sensorimotor cortical areas early on and induce freezing in the observers' motor system, particularly when ...observing fearful EBL. To provide insights into the interplay between somatosensory and motor areas during observation of EBL, here, we used high‐density electroencephalography (hd‐EEG) in healthy humans while they observed EBL stimuli involving fearful and neutral expressions. To capture early sensorimotor brain response, we focused on P100 fronto‐central event‐related potentials (ERPs) and event‐related desynchronization/synchronization (ERD/ERS) in the mu‐alpha (8–13 Hz) and lower beta (13–20 Hz) bands over the primary motor (M1) and somatosensory (S1) cortices. Source‐level ERP and ERD/ERS analyses were conducted using eLORETA. Results revealed higher P100 amplitudes in motor and premotor channels for ‘Neutral’ compared with ‘Fear’. Additionally, analysis of ERD/ERS showed increased beta band desynchronization in M1 for ‘Neutral’, and the opposite pattern in S1. Source‐level estimation showed significant differences between conditions mainly observed in the beta band over sensorimotor areas. These findings provide high‐temporal resolution evidence suggesting that seeing fearful EBL induces early activation of somatosensory areas, which in turn could suppress M1 activity. These findings highlight early dynamics within the observer's sensorimotor system and hint at a sensorimotor mechanism supporting freezing during the processing of EBL.
By means of hd‐EEG, we provide high‐temporal resolution evidence that seeing fearful emotional body language (EBL) induces early activation of somatosensory areas, which in turn suppress M1 activity. These findings provide high‐temporal resolution evidence suggesting that seeing fearful EBL induces early activation of somatosensory areas, which in turn could suppress M1 activity.
Current theories of object perception emphasize the automatic nature of perceptual inference. Repetition suppression (RS), the successive decrease of brain responses to repeated stimuli, is thought ...to reflect the optimization of perceptual inference through neural plasticity. While functional imaging studies revealed brain regions that show suppressed responses to the repeated presentation of an object, little is known about the intra‐trial time course of repetition effects to everyday objects. Here, we used event‐related potentials (ERPs) to task‐irrelevant line‐drawn objects, while participants engaged in a distractor task. We quantified changes in ERPs over repetitions using three general linear models that modeled RS by an exponential, linear, or categorical “change detection” function in each subject. Our aim was to select the model with highest evidence and determine the within‐trial time‐course and scalp distribution of repetition effects using that model. Model comparison revealed the superiority of the exponential model indicating that repetition effects are observable for trials beyond the first repetition. Model parameter estimates revealed a sequence of RS effects in three time windows (86–140, 322–360, and 400–446 ms) and with occipital, temporoparietal, and frontotemporal distribution, respectively. An interval of repetition enhancement (RE) was also observed (320–340 ms) over occipitotemporal sensors. Our results show that automatic processing of task‐irrelevant objects involves multiple intervals of RS with distinct scalp topographies. These sequential intervals of RS and RE might reflect the short‐term plasticity required for optimization of perceptual inference and the associated changes in prediction errors and predictions, respectively, over stimulus repetitions during automatic object processing.
We studied the time course of repetition effects on event related potentials (ERP) to objects. Model comparison favored an exponential model of repetition suppression—compared to linear or categorical “change detection”—indicating that repetition effects are observable in trials beyond the first repetition. We found successive intervals of repetition effects with distinct scalp distribution which might reflect the short‐term plasticity required for optimization of perceptual inference.
Substantial studies have investigated the social influence effect; however, how individuals with different social value orientations (SVOs), prosocials and proselfs, respond to different social ...influences remains unknown. This study examines the impact of positive and negative social information on the responses of people with different SVOs. A face‐attractiveness assessment task was employed to investigate the relationships between influence probability, memory, and event‐related potentials of social influence. A significant interactional effect suggested that prosocials and proselfs reacted differently to positive (group rating was more attractive) and negative (group rating was less attractive) social influences. Specifically, proselfs demonstrated significantly higher influence probability, marginally better recall performance, smaller N400, and larger late positive potential on receiving negative influence information than on receiving positive influence information, while prosocials showed no significant differences. Overall, correlations between N400/LPP, influence probability, and recall performance were significant. The above results indicate the modulating role of SVO when responding to social influence. These findings have important implications for understanding how people conform and how prosocial behavior occurs.
SVO modulates conformity and memory preference for positive and negative social influence. The modulating role of SVO on neural responses is reflected by N400 and late positive potential.
The reliability of individual trial event‐related potential (ERP) components extracted from electroencephalogram has been consistently questioned since ERP research began. This ambivalence is based ...on misunderstood assumptions stemming from Cronbach and Classical Test Theory. Contemporary methods allow for the reliability of individual ERP trials to be estimated and for analyses of these trial‐level ERP components to be meaningfully parsed. We illustrate the use of Generalizability Theory procedures in estimating the reliability of trial‐level ERPs using the late positive potential (LPP), a neural measure of motivated attention toward emotionally evocative stimuli. Individuals (N = 88) completed a passive viewing task while continuous EEG was recorded. Variability in trial‐level LPP responses was decomposed into facets corresponding to individual differences, chronological trial within block, stimulus type, their two‐way interactions, and specific stimuli. We estimated various reliability coefficients and found that both overall and category‐specific person‐level LPP estimates have good‐to‐excellent reliability, while the reliability of within‐person differences (i.e., change) between arousal categories was fair for the early LPP. These results were generally consistent across time windows, but were highest early in the LPP time course. We argue that investigating reliability using trial‐level data allows researchers to pursue hypotheses focused on neurophysiological dynamics that unfold over the course of an experiment and not risk false inferences (i.e., ecological fallacy) when using person‐level aggregates to deduce such processes. Moreover, such analyses provide information that allows researchers to optimize their protocols by potentially reducing the number of individual trials, burden on participants, and cost, while retaining sufficient reliability.
We illustrate the use of Generalizability Theory procedures in estimating the reliability of trial‐level ERPs using the late positive potential (LPP). We found that overall and category‐specific person‐level LPP estimates have good‐to‐excellent reliability. Establishing reliability using trial‐level data allows researchers to optimize protocols and pursue hypotheses focused on neurophysiological dynamics.
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