Predictive value of novel stimuli modifies visual event-related potentials and behavior

Decrease in the P2 Amplitude of Object Working Memory after 8 h-Recovery Sleep Following 36 h-Total Sleep Deprivation: An ERP Study

The impact of sleep deprivation on working memory can only be reversed by recovery sleep (RS). However, there are limited electrophysiological studies on the effect of RS on the improvement in working memory after sleep deprivation, and the changes in the early components of event-related potentials (ERPs) before and after RS are still unclear. Therefore, this study aims to explore the effects of RS on the earlier ERP components related to object working memory following 36 h of total sleep deprivation (TSD). Twenty healthy male participants performed an object working memory task after 36 h of TSD and after 8 h of RS. Electroencephalogram data were recorded accordingly while the task was performed. Repeated ANOVA showed that P2 amplitudes related to object working memory decreased significantly after 8 h of RS compared to after a 36 h period of TSD, but there was no significant difference from baseline (BS), which indicates a trend of recovery to the baseline state. An 8 h RS can partially improve impaired object working memory caused by TSD. However, a longer period of RS is needed for the complete recovery of cognitive function after a long period of TSD.

Dysfunction of visual novelty detection in physical but not social anhedonia in a non-clinical sample

Background/objective

Despite its obvious motivational impairment, anhedonia as a transdiagnostic psychopathological construct is accompanied by deficits in attention function. Previous studies have identified voluntary attention anomalies in anhedonia, but its involuntary attention has received less study.

Method

Using a visual novelty oddball task, the current event-related potential study assessed electrophysical correlates underlying mismatch detection in anhedonia with a non-clinical sample. Well-matched healthy control (N = 28; CNT), social anhedonia (N = 27; SA), and physical anhedonia (N = 26; PA) groups were presented standard, target, and perceptually novel stimuli while their EEG was recording.

Results

The PA group relative to the CNT group exhibited a reduced N2 to novel stimuli but not to target stimuli. In contrast, the SA group as compared to the other two groups showed comparable N2 responses to both target and novel stimuli. Control analyses indicated that these patterns were unaffected by depression symptoms.

Conclusions

These findings suggest that anhedonia is a heterogenous construct associated with impairments in early detection of visual novelty in physical but not social anhedonia, highlighting that dysfunction in involuntary attention may play a mediating role in the development, maintenance, and consequences of anhedonia-related psychopathology.

Decline in the integration of top-down and bottom-up attentional control in older adults with mild cognitive impairment

Individuals with mild cognitive impairment (MCI) have deficits in goal-directed top-down and stimulus-driven bottom-up attentional control. However, it remains unclear whether and how the interaction between the two processes is altered in individuals with MCI. We collected electroencephalography (EEG) data from 30 older adults with MCI and 30 demographically matched healthy controls (HCs) when they were performing a perceptual decision-making task, in which we manipulated the cognitive load involved in task-relevant top-down processing and the surprise level involved in task-irrelevant bottom-up processing. We found the significant group difference in the interaction between top-down and bottom-up processes. HCs showed enlarged P3 and strengthened event-related microstate C on high (vs. low) surprise level trials under high cognitive load, while there was no such surprise effect suggesting distraction under low cognitive load. In contrast, participants with MCI showed increased P2 and P3 amplitudes and strengthened microstates C and D on high (vs. low) surprise level trials under low cognitive load yet no surprise effect under high load. These results suggested that participants with MCI were distracted by task-irrelevant information under low cognitive load, while under high load, they might experience a passive inhibition on the task-irrelevant bottom-up processing because of the exhaustion of attentional resources; in addition, this altered interaction observed in the MCI group occurred at the stages of selective attention and uncertainty reduction.

Associations of Hyperactivity and Inattention Scores with Theta and Beta Oscillatory Dynamics of EEG in Stop-Signal Task in Healthy Children 7-10 Years Old

Simple Summary

Most studies on ADHD have been focused on the comparisons between healthy subjects and clinical patients. The dimensional approaches propose that the main pathological behavioral domains are distributed in the normal population and not only in individual categories of people (as assumed in traditional schemes of comparisons between patients and controls). In the current study, we used a similar approach to identify potential markers of ADHD by studying the EEG dynamics of healthy children with a natural variability in hyperactivity and inattention scores during performance of the Stop-Signal task. We found that hyperactivity/inattention scores were positively associated with RT variability. Hyperactivity/inattention scores were negatively associated with an increase in beta spectral power in the first 200 ms and positively associated with an increase in theta rhythm at about 300 ms after presentation of the Go stimulus. It has been hypothesized that such results imply insufficient vigilance in the early stages of perception and subsequent compensatory enhancing of attention to the stimulus in children with higher hyperactivity and inattention scores.

Abstract

In the current study, we aimed to investigate the associations between the natural variability in hyperactivity and inattention scores, as well as their combination with EEG oscillatory responses in the Stop-Signal task in a sample of healthy children. During performance, the Stop-Signal task EEGs were recorded in 94 Caucasian children (40 girls) from 7 to 10 years. Hyperactivity/inattention and inattention scores positively correlated with RT variability. Hyperactivity/inattention and inattention scores negatively correlated with an increase in beta spectral power in the first 200 ms after presentation of the Go stimulus. Such results are in line with the lack of arousal model in ADHD children and can be associated with less sensory arousal in the early stages of perception in children with symptoms of inattention. The subsequent greater increase in theta rhythm at about 300 ms after presentation of the Go stimulus in children with higher inattention scores may be associated with increased attention processes and compensation for insufficient vigilance in the early stages of perception.

Altered Functional Connectivity in Children with ADHD Revealed by Scalp EEG: An ERP Study

Attention deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental brain disorders in childhood. Despite extensive researches, the neurobiological mechanism underlying ADHD is still left unveiled. Since the deficit functions, such as attention, have been demonstrated in ADHD, in our present study, based on the oddball P3 task, the corresponding electroencephalogram (EEG) of both healthy controls (HCs) and ADHD children was first collected. And we then not only focused on the event-related potential (ERP) evoked during tasks but also investigated related brain networks. Although an insignificant difference in behavior was found between the HCs and ADHD children, significant electrophysiological differences were found in both ERPs and brain networks. In detail, the dysfunctional attention occurred during the early stage of the designed task; as compared to HCs, the reduced P2 and N2 amplitudes in ADHD children were found, and the atypical information interaction might further underpin such a deficit. On the one hand, when investigating the cortical activity, HCs recruited much stronger brain activity mainly in the temporal and frontal regions, compared to ADHD children; on the other hand, the brain network showed atypical enhanced long-range connectivity between the frontal and occipital lobes but attenuated connectivity among frontal, parietal, and temporal lobes in ADHD children. We hope that the findings in this study may be instructive for the understanding of cognitive processing in children with ADHD.

Event-related potentials using the auditory novel paradigm in patients with myotonic dystrophy

Many neuropsychological disorders, especially attentional abnormality, are present in patients with myotonic dystrophy type 1 (DM1), but the underlying mechanisms remain unclear. This study aimed to evaluate attention function by auditory event-related potential (ERP) P3a (novelty paradigm) in DM1 patients. A total of 10 young DM1 patients (mean age 30.4 years) and 14 age-matched normal controls participated in this study. ERPs were recorded using an auditory novel paradigm, consisting of three types of stimuli, i.e., standard sound (70%), target sound (20%), and various novel sounds (10%), and participants pressed buttons to the target sounds. ERP components P3b after the target stimuli and P3a following the novel stimuli were analyzed. Correlations of neuropsychological evaluations with the amplitudes and latencies of P3b and P3a were analyzed in DM1 patients. We found that P3a latency was significantly delayed in patients with DM1 compared with normal controls, although the latency and amplitude of P3b in DM1 patients were comparable with those in normal controls. The achievement rates of both the Symbol Digit Modality Test and the Paced Auditory Serial Addition Test were significantly correlated with P3a amplitude, as well as P3b amplitude. These results suggest that ERPs, including P3a and P3b, provide important insights into the physiological basis of neuropsychological abnormalities in patients with DM1, especially from the viewpoint of the frontal lobe and attention function.

N2b Reflects the Cognitive Changes in Executive Functioning After Concussion: A Scoping Review

Objectives: The N2b is an event-related potential (ERP) component thought to index higher-order executive function. While the impact of concussion on executive functioning is frequently discussed in the literature, limited research has been done on the role of N2b in evaluating executive functioning in patients with concussion. The aims of this review are to consolidate an understanding of the cognitive functions reflected by the N2b and to account for discrepancies in literature findings regarding the N2b and concussion.

Methods: A scoping review was conducted on studies that used the N2b to measure cognitive functioning in healthy control populations, as well as in people with concussions.

Results: Sixty-six articles that met inclusion criteria demonstrated that the N2b effectively represents stimulus-response conflict management, response selection, and response inhibition. However, the 19 included articles investigating head injury (using terms such as concussion, mild head injury, and mild traumatic brain injury) found widely varied results: some studies found the amplitude of the N2b to be increased in the concussion group, while others found it to be decreased or unchanged.

Conclusion: Based on the available evidence, differences in the amplitude of the N2b have been linked to response selection, conflict, and inhibition deficits in concussion. However, due to large variations in methodology across studies, findings about the directionality of this effect remain inconclusive. The results of this review suggest that future research should be conducted with greater standardization and consistency.

A newly developed free software tool set for averaging electroencephalogram implemented in the Perl programming language

Background

Considering the need for daily activity analysis of older adults, development of easy-to-use, free electroencephalogram (EEG) analysis tools are desired in order to decrease barriers to accessing this technology and increase the entry of a wide range of new researchers.

New method

We describe a newly developed tool set for EEG analysis, enabling import, average, waveform display and iso-potential scalp topographies, utilizing the programming language Perl.

Results

The basic processing, including average, display waveforms, and isopotential scalp topography was implemented in the current system. The validation was examined by making difference waveforms between the results using the current analysis system and a commercial software.

Comparison with Existing Method(s): The current software tool set consists of free software. The scripts are easily editable by any user and there are no black boxes.

Conclusions

The currently reported procedures provide an easy-to-begin, flexible, readable, easy-to-modify basic tool set for EEG analysis and is expected to recruit new EEG researchers.

Neurophysiological correlates of visuospatial attention and the social dynamics of gaze processing

The reflexive orienting response triggered by nonpredictive gaze cues is thought to be driven by a dedicated social neural network responsible for directing attention toward socially salient information. However, atypical processing of eye gaze using concomitant perceptual features has been proposed to underlie attentional orienting in groups with impairments in social cognition. Here, we examined the neurophysiological indices of visuospatial attention during a spatial cueing task, considering individual variability in social cognition in typically developing individuals, and the relative salience of social gaze and perceptual motion cues. We found enhanced neural activation to incongruent cues, wherein modulation of the N2b serves as a marker of the allocation of attention in the spatial domain. Our findings suggest the social gaze cue is less salient for those with greater autistic traits. An attentional bias toward perceptual motion cues correlated with greater social anxiety and alexithymia, and thus may reflect reduced sensitivity to social stimuli. These results provide evidence for likely neurophysiological mechanisms underlying gaze cueing and offer insight into the use of qualitatively different cognitive mechanisms used to access social information. Such paradigms provide potential insight into normative orienting responses reported in atypical groups and would benefit investigations of gaze following abilities in clinical populations.

The effects of negative air ions on cognitive function: an event-related potential (ERP) study

This study investigated the effects of negative air ions (NAIs) on cognitive function in young male adults, specifically examined whether NAIs could influence the behavioral and neuroelectrical indices of inhibition. Thirty-nine young adults participated in the NAI and the control sessions in a counterbalanced order. A computerized Stroop color-word test was administrated, and N2 of the event-related potential was recorded and then analyzed. The results revealed that participants in the NAI session demonstrated shorter reaction times and higher accuracy for both Stroop congruent and incongruent trials. Larger N2 amplitudes were also observed in the NAI session than in the control session, whereas no alterations in the latencies were found. These findings suggest that NAIs resulted in a general improvement in both basic information processing and inhibition. This facilitation may be related to an enhanced neuronal processing or alertness status reflected by larger amplitudes of the N2 component.

N2 amplitude modulation across the antisocial spectrum: a meta-analysis

Despite the accumulated knowledge on antisocial behavior and the positive event-related potential peaking around 300 ms (P3), less is known about the preceding negative electrophysiological response around 200 ms (N2). A systematic search of the literature was conducted to analyze the N2 modulation across the antisocial spectrum. Thirty-seven studies (n = 1199) were retrieved to the quantitative analysis. Reduced N2 amplitudes were found in the more severe antisocial manifestations (violent behavior and antisocial personality disorder), which is consistent with previous findings on P3 alterations and N2 reduced amplitudes in externalizing disorders. Findings on psychopathy were mixed, also in accordance with previous P3 results. From a dimensional lens, this supports the heterogeneity of the psychopathic personality structure: impulsivity features are a closer attribute of antisocial behavior and thus may be associated with N2 reduction, while adaptive psychopathic traits may be associated with intact (or even increased) N2 amplitude. The increased N2 amplitudes observed in impulsive behavior challenge, however, the previous meta-analytic findings. As most of the studies on impulsivity include subclinical samples, it leads to the hypothesis that some compensatory mechanisms can still occur at a subclinical level, reflecting the need for heightened allocation of brain resources to yield similar performances. Importantly, inhibition was the core deficit to explain N2 blunted amplitudes, alongside with deficits in the frontal brain region. From our findings, the reduction in P3 amplitude across the antisocial spectrum may be detected in the previous N2 time window.

Flanker paradigm contains conflict and distraction factors with distinct neural mechanisms: an ERP analysis in a 2-1 mapping task

Behavioral studies using the flanker 2-1 mapping task suggest that both stimulus and response conflicts contribute to flanker conflict effect. However, both are intertwined with distraction effect. Their underlying neural mechanisms remain unclear. We applied a perceptual flanker 2-1 mapping task to 24 healthy young adults, while the event-related potentials were recorded. The task included stimulus-incongruent (SI), response-incongruent (RI), congruent (CO) and neutral (NE) stimuli. Our reaction time data demonstrated conflict effect, distraction effect and their interaction. Furthermore, the conflict factor successively enhanced the frontal P2 (160-240 ms), the posterior N2pc (200-240 ms), the fronto-central and the right frontal N2b (240-420 ms), and the posterior N2c (320-420 ms). Only the frontal P2 was larger for RI than SI. The distraction factor increased the right N2pc and reduced the left parietal P3b (460-480 ms). Overall, our findings suggested that the flanker conflict involved an early attentional processing of task-relevant and distractive information, and a later processing of conflict evaluation and response inhibition.

FEF Excitability in Attentional Bias: A TMS-EEG Study

The role of distinct cortical regions in guiding social orienting needs further investigation. Our aim was to explore the contribution of the frontal eye field (FEF) in early orienting of attention towards stimuli with social value. We used a TMS-EEG approach to investigate event related potentials (ERPs; no-TMS block) and TMS evoked potentials (TEPs; TMS block) during the cueing phase of a modified version of the dot-probe task, comparing competing (face vs. house) and not competing (house vs. house) conditions. Our results revealed an increased amplitude of ERP components in the competing condition, showing greater posterior N170 and fronto-central vertex positive potential (VPP) and an enhanced frontal negative component at 250-270 ms from cue onset. TMS pulses over the FEF induced similar N170 and VPP amplified components. In addition, in the ERPs, a reduced positivity at 400 ms was shown when the face appeared on the left side vs. the right side of space. In contrast, in the TMS blocks, we found lateralized effects on N170 depending on the side of face presentation. The enhanced cortical excitability induced by TMS over the right FEF significantly correlated with the performance on the behavioral task, suggesting a link between the FEF activity during the cueing phase of the dot-probe task and the subsequent behavioral response times to the targets.

Validation of a multidirectional locomotive dual-task paradigm to evaluate task-related differences in event-related electro-cortical activity

A fundamental aspect of everyday function is the ability to simultaneously execute both cognitive and motor tasks. The ability to perform such tasks is commonly assessed using a dual-task paradigm that has the capacity to manipulate both cognitive and motor components of an action. Dual-task performance provides an opportunity to obtain an insight into how cognitive and motor function are affected during natural tasks (e.g., locomotion). The following study aimed to determine the effectiveness of using a goal-directed multidirectional locomotor task to measure differences in task-related (tasks of increasing difficulty) electro-cortical activity. In the single-task condition participants walked around a grid-based track, performing directional changes at each intersection in response to a sensory stimulus. In the dual-task condition participants performed the same primary task while performing a simultaneous memory recall task. Behavioural differences in trial completion time and electro-cortical activity were identified in relation to the posterior N2 and P3 component mean amplitudes. The results showed that, while performing a higher-level cognitive task during walking (dual-task), interference arises in a shared system that influences neural mechanisms involved in attention and selection for action, and later cognitive processes recruited in working memory and cognitive control. This study extends previous work and shows that performing a more complex cognitive task while walking, elicits interference effects sensitive to higher-level cognitive processes, and takes the next step towards measurement of electro-cortical activity within naturalistic environments.

The N1-N2-LPC Pattern in Processing Advertising Pictorial Metaphors: An ERP Study

We investigated what the temporal processing is of advertising pictorial metaphors. After presenting “a word of product” and “its advertising pictures,” the experiment instructed participants to make a follow-up true–false judgment considering what the picture intended to suggest. A repeated-measures ANOVAs for a 2 (picture type: metaphor, non-metaphor) × 2 (prime–target condition: congruent, incongruent) × 3 (electrode site: Fz, Cz, Pz) experimental condition was conducted on three components, N1 (100–150 ms), N2 (200–300 ms), and LPC (400–600 ms and 600–1,000 ms). The results show that metaphor pictures elicited larger amplitude in N1 (broadly distributed), N2 (frontally biased) and LPC (parietally biased), roughly reflecting an entire process with an initial response to visual onsets, an early recognition of semantic violations and a prolonged reanalysis process of semantic integration. We argue that, different than verbal metaphors, this faster processing occurred due to the involvement of visual pathway.

The Effect of Background Music on Inhibitory Functions: An ERP Study

The influence of background music on cognitive functions is still a matter of debate. In this study, we investigated the influence of background music on executive functions (particularly on inhibitory functions). Participants completed a standardized cued Go/NoGo task during three different conditions while an EEG was recorded (1: with no background music, 2: with relaxing, or 3: with exciting background music). In addition, we collected reaction times, omissions, and commissions in response to the Go and NoGo stimuli. From the EEG data, event-related potentials (ERPs) were calculated for the Go and NoGo trials. From these ERPs, the N2 and P3 components were specifically analyzed since previous studies have shown that these components (and particularly the Go-NoGo difference waves) are strongly associated with inhibitory functions. The N2 and P3 components of the difference waves (N2d and P3d) were used for statistical analyses. The statistical analyses revealed no differences between the three conditions in terms of amplitudes and latencies of the N2d and P3d components. In addition, reaction times, omissions, and commissions were comparable across all conditions. Our results suggest that in the context of this paradigm, music as background acoustic stimulation has no detrimental effects on the performance of a Go/NoGo task and neural underpinnings.

Neural responses to one's own name under mortality threat

Recent behavioral research has shown evidence for greater inclination to avoid symbolic cues of mortality threats in nonbelievers than Christians. However, the neurocognitive mechanisms underlying religious influences on behavioral tendency to avoid mortality threats remain unknown. We tested the hypothesis of distinct arousal/attention-related brain responses to self-related information under mortality in nonbelievers and Christians. We recorded event-related brain potentials (ERPs) from Christians and nonbelievers while they viewed their own names and a stranger's name (i.e., Zuma) that flashed around a cue word (i.e., death, pain or life) located at the center of a screen. While own name vs. a stranger's name induced faster responses and larger P3 amplitudes, the P3 amplitudes to own name showed distinct patterns of modulations by the cue words in nonbelievers and Christians. Specifically, own name elicited larger P3 amplitudes in the death than pain/life cue conditions in nonbelievers but not in Christians. Moreover, the differential P3 amplitude to own names in the death vs. life cue conditions predicted greater inclination to avoid mortality threats in nonbelievers but not in Christians. Our findings provide a neurocognitive account of increased behavioral tendency to avoid mortality threats in nonbelievers than in Christians.

Sequential congruency effects reveal differences in disengagement of attention for monolingual and bilingual young adults

Three studies examined the hypothesis that bilinguals can more rapidly disengage attention from irrelevant information than monolinguals by investigating the impact of previous trial congruency on performance in a simple flanker task. In Study 1, monolingual and bilingual young adults completed two versions of a flanker task. There were no differences between language groups on mean reaction time using standard analyses for congruent or incongruent trials or the size of the flanker effect. Sequential congruency effects (SCEs) however, which account for previous trial congruency, were smaller for bilinguals than for monolinguals. This finding was strongest at the shortest response-to-stimulus interval (RSI). Study 2 replicated this effect using a slightly different flanker task and a shorter RSI than study 1. Study 3 showed that at long RSIs, where behavioral SCE differences between groups disappear because of sufficient time to recover from the previous trial, event-related potentials demonstrated a continued influence of previous trial congruency for monolinguals but not bilinguals at both the N2 and the P3, replicating the reaction time effects in Studies 1 and 2. Together, these studies demonstrate that bilinguals experience less influence from previous trial congruency and have greater ability to disengage attention from the previous trial in order to focus attention on the current trial than is found for monolinguals.

Response inhibition or evaluation of danger? An event-related potential study regarding the origin of the motor interference effect from dangerous objects

Previous studies have identified an interference effect from dangerous objects on prepared responses. However, its origin remains arguable. This study investigated the neural processes of this motor interference effect. The design adopted a motor priming paradigm mixed with a Go/NoGo task. Pictures of a left or right hand were used as primes, and green (Go signal) or red (NoGo signal) circles superimposed on dangerous or safe objects were used as targets. Participants were instructed to prepare the corresponding key press using the hand that was consistent with the handedness of the prime and not to execute until a Go signal appeared. Behavioral results indicated longer reaction times and a trend that participants made more errors for the dangerous condition than for the safe condition in the Go trials. However, the difference between the error rates for the dangerous and safe conditions did not emerge in the NoGo trials. Event-related potential analysis revealed a similar effect on the P3 component, which may reflect an assignment of cognitive resources to evaluate danger. More positive parietal P3 amplitudes were identified in response to the dangerous condition in the Go trials. However, the difference in the P3 amplitudes between the dangerous and safe conditions was not significant in the NoGo trials. Together, the motor interference effect from dangerous objects may originate from the danger evaluations. Furthermore, differences between the dangerous and safe conditions also emerged in the P1, posterior N1, P2, and posterior N2 components; the possible processes that underlie these components were discussed.

Abnormal Neural Basis of Emotional Conflict Control in Treatment-Resistant Depression

Emotional conflict has received increased attention as a research topic. The objective of this study is to confirm that the processing of emotional conflict is impaired in treatment-resistant depression (TRD). We compared the event-related potentials of 17 patients with TRD and 17 healthy controls during the face-word Stroop task, which is an effective way of assessing the effects of emotional conflict directly. Compared with healthy controls, the accuracy scores of the TRD patients were lower in both "congruent stimuli" and "incongruent stimuli" conditions, and their response times were longer. The TRD patients also had larger N2 amplitudes over the frontal region, regardless of stimulus condition, which might reflect that TRD patients pay more attention to emotional information. A larger P3 amplitude over the frontal region for "incongruent stimuli minus congruent stimuli" was also found among patients with TRD, which indicates interference effects in the Stroop task. The results of this study provide novel behavioral and neurophysiological evidence of anomalies in cognitive inhibition among patients with TRD using the word-face task. These findings not only improve our understanding of deficient inhibition in TRD, but also pave the way for a cognitive neuropsychiatric model of depression.

Consonantal overlap effects in a perceptual matching task

This study investigates the processing of letter position coding by exploring whether or not two explicitly presented words that share the same consonants, but that differ in their vowels, exert mutual interference more than two words that do not share their consonants. In an explicit perceptual matching task, word targets were preceded by a word reference that could share all the consonants either at the same position or in a different absolute position (while keeping their relative position intact) or preceded by an unrelated reference. Experiment 1 showed larger discrimination costs for pairs sharing the consonants at the same position than for pairs sharing their consonants in a different position. Experiment 2 investigated when and how the types of overlap influence word target processing by using event-related potential recordings. The ERP results showed a Relatedness effect only for targets that share the consonants at the same position from 120 to 600 ms post-target onset, whereas targets that share their consonants in different positions in the string produced null effects. Altogether, these data suggest that targets containing the same consonants included in the references in the same positions are processed as being highly similar to them, thus distorting target processing. Furthermore, these data suggest possible mechanisms of competition between lexical representations of the reference and target stimuli.

ERPs in an oddball task under vection-inducing visual stimulation

The neural mechanisms underlying the vection illusion are not fully understood. A few studies have analyzed visually evoked potentials or event-related potentials (ERPs) when participants were exposed to vection-inducing stimulation. However, none of them tested how such stimulation influences the brain activity during performance of the simultaneous visual task. In the present study, ERPs were recorded while subjects (N = 19) performed a discrimination oddball task. Two stimuli (O or X) were presented on the background of central and peripheral visual fields consisting of altered black and white vertical stripes that were stationary or moving horizontally. Three different combinations of these fields were created: (1) both center and periphery stationary (control condition), (2) both center and periphery moving, (3) center stationary and periphery moving. Mean reaction times to targets were shortest in the control condition. The amplitudes of P1 and N2 at occipital locations, and the amplitude of P3 at frontal, central, and parietal locations, were attenuated, and the P3 exhibited longer peak latency when both central and peripheral visual fields were moving. These potentials reflect initial sensory processing and the degree of attention required for processing visual stimuli and performing the task. Our findings suggest that the integration of central and peripheral moving visual fields enhances the vection illusion and slows down reaction times to targets in the oddball task and disrupts the magnitude of electrophysiological responses to targets.

ERP Correlates of Proactive and Reactive Cognitive Control in Treatment-Naïve Adult ADHD

This study investigated whether treatment naïve adults with Attention Deficit Hyperactivity Disorder (ADHD; n = 33; 19 female) differed from healthy controls (n = 31; 17 female) in behavioral performance, event-related potential (ERP) indices of preparatory attention (CueP3 and late CNV), and reactive response control (Go P3, NoGo N2, and NoGo P3) derived from a visual cued Go/NoGo task. On several critical measures, Cue P3, late CNV, and NoGo N2, there were no significant differences between the groups. This indicated normal preparatory processes and conflict monitoring in ADHD patients. However, the patients had attenuated Go P3 and NoGoP3 amplitudes relative to controls, suggesting reduced allocation of attentional resources to processes involved in response control. The patients also had a higher rate of Go signal omission errors, but no other performance decrements compared with controls. Reduced Go P3 and NoGo P3 amplitudes were associated with poorer task performance, particularly in the ADHD group. Notably, the ERPs were not associated with self-reported mood or anxiety. The results provide electrophysiological evidence for reduced effortful engagement of attentional resources to both Go and NoGo signals when reactive response control is needed. The absence of group differences in ERP components indexing proactive control points to impairments in specific aspects of cognitive processes in an untreated adult ADHD cohort. The associations between ERPs and task performance provided additional support for the altered electrophysiological responses.

ATTENTION FUNCTIONING IN CHILDREN WITH PRENATAL DRUG EXPOSURE

Children born to drug abusers are exposed to teratogenic influences on intrauterine brain development and undergo postnatal withdrawal. We investigated the interplay of different domains and levels of attention functioning in 24 prenatally exposed and 25 nonexposed children who were 5 to 6 years old. Assessment included parent ratings and neuropsychological and electrophysiological methods. Exposed children had a higher prevalence of attention deficit hyperactivity symptoms, tended to have poorer performance in an attention test battery, and showed EEG alterations in P3 and N2c. Findings suggest long-term effects of prenatal drug exposure on specific domains and on different levels of attention functioning.

Buffering effect of money priming on negative emotions—An ERP study

Recent studies have accumulated evidences that merely reminding people of money could lead to behavioral changes including alleviating both physical pain and social distress. However, the underlying neural mechanism regarding such pain-buffering effect of money is not clear. In this paper, we applied event-related potentials (ERP) to investigate the neural effect of money reminders on induced negative emotions. Subjects were first primed of money images and subsequently viewing unpleasant pictures, while EEG was recorded. Behavioral results suggested a reduced sensitivity to unpleasant pictures after participants being reminded of money. ERP data showed that money priming, compared to neutral priming, generated a larger N2 in frontal and posterior areas, reflecting an endogenous mental conflict and the recruitment of attention resources, and a smaller late positive potential (LPP) in parietal and occipital regions, indicating a regulating process of negative emotions. Additionally, how brain responded to money and neutral stimuli were also examined, indexed by "N170-P2" complex. This study provided additional neurophysiological evidences to support previous behavioral researches on money priming and discussed the two separated neural dynamic stages involved in emotion regulation.

Differentiating the functional contributions of resting connectivity networks to memory decision-making: fMRI support for multistage control processes

Neural substrates of memory control are engaged when participants encounter unexpected mnemonic stimuli (e.g., a new word when told to expect an old word). The present fMRI study (n = 18) employed the likelihood cueing recognition task to elucidate the role of functional connectivity (fcMRI) networks in supporting memory control processes engaged by these unexpected events. Conventional task-evoked BOLD analyses recovered a memory control network similar to that previously reported, comprising medial prefrontal, lateral prefrontal, and inferior parietal regions. These were split by their differential affiliation to distinct fcMRI networks ("conflict detection" and "confirmatory retrieval" networks). Subsequent ROI analyses clarified the functional significance of this connectivity differentiation, with "conflict" network-affiliated regions specifically sensitive to cue strength, but not to response confidence, and "retrieval" network-affiliated regions showing the opposite pattern. BOLD time course analyses corroborated the segregation of memory control regions into "early" conflict detection and "late" retrieval analysis, with both processes underlying the allocation of memory control. Response specificity and time course findings were generalized beyond task-recruited ROIs to clusters within the large-scale fcMRI networks, suggesting that this connectivity architecture could underlie efficient processing of distinct processes within cognitive tasks. The findings raise important parallels between prevailing theories of memory and cognitive control.

Neural correlates of local contextual processing across stimulus modalities and patient populations

The objective of the current review is to integrate information from a series of studies, employing a paradigm that evaluates local contextual processing using electrophysiological measures. Collectively these studies provide an overview of how utilization of predictive context changes as a function of stimulus modality and across different patient populations, as well as the networks that may be critical for this function. The following aspects of local contextual processing will be discussed and reviewed: (i) the correlates associated with contextual processing that have been identified in healthy adults, (ii) stimulus modality effects, (iii) specific alterations and deficits of local contextual processing in aging and across different neurological and psychiatric patient populations, including patients with prefrontal cortex lesions, Parkinson's disease, schizophrenia, and major depressive disorder, (iv) the potential for utilizing the correlates of local context as biomarkers for frontal cognitive dysfunction and (v) the role of frontal networks in the processing of contextual information. Overall findings show that behavioral and neural correlates associated with processing of local context are comparable across stimulus modalities, but show specific alterations in aging and across different neurological and psychiatric disorders.

Local contextual processing in major depressive disorder

OBJECTIVE

The study investigated local contextual processing in patients with major depressive disorder (MDD). This was defined as the ability to utilize predictive contextual information to facilitate detection of predictable versus random targets.

METHOD

We recorded EEG in 15 MDD patients and 14 age-matched controls. Recording blocks consisted of targets preceded by randomized sequences of standards and by sequences of standards that included a predictive sequence signaling the occurrence of a subsequent target event.

RESULTS

Both MDD patients and age-matched controls demonstrated a significant reaction time (RT) and P3b latency differences between predicted and random targets. However, patients demonstrated a specific prolongation of these measures during processing of predicted targets, as well as an attenuation of P3b amplitudes for the predictive sequence. In addition, patients target N1 amplitudes were attenuated compared with controls.

CONCLUSION

MDD patients were able to utilize predictive context in order to facilitate processing of deterministic targets, however, this ability was limited compared to controls, as demonstrated by context-dependent P3b deficits.

SIGNIFICANCE

These findings suggest that patients with major depression have altered processing of local contextual processing.

ERP evidence suggests executive dysfunction in ecstasy polydrug users

BACKGROUND

Deficits in executive functions such as access to semantic/long-term memory have been shown in ecstasy users in previous research. Equally, there have been many reports of equivocal findings in this area. The current study sought to further investigate behavioural and electro-physiological measures of this executive function in ecstasy users.

METHOD

Twenty ecstasy-polydrug users, 20 non-ecstasy-polydrug users and 20 drug-naïve controls were recruited. Participants completed background questionnaires about their drug use, sleep quality, fluid intelligence and mood state. Each individual also completed a semantic retrieval task whilst 64 channel Electroencephalography (EEG) measures were recorded.

RESULTS

Analysis of Variance (ANOVA) revealed no between-group differences in behavioural performance on the task. Mixed ANOVA on event-related potential (ERP) components P2, N2 and P3 revealed significant between-group differences in the N2 component. Subsequent exploratory univariate ANOVAs on the N2 component revealed marginally significant between-group differences, generally showing greater negativity at occipito-parietal electrodes in ecstasy users compared to drug-naïve controls. Despite absence of behavioural differences, differences in N2 magnitude are evidence of abnormal executive functioning in ecstasy-polydrug users.

Human electrophysiological correlates of learned irrelevance: effects of the muscarinic M1 antagonist biperiden

Learned irrelevance (LIrr) refers to a reduction in associative learning after pre-exposure of the conditioned and unconditioned stimulus in a non-contingent fashion. This paradigm might serve as a translational model for (pre)attentive information processing deficits in schizophrenia. This is the first study to investigate the event-related potentials (ERPs) of a within-subject LIrr paradigm in humans. Furthermore, the effects of the muscarinic M1 antagonist biperiden on LIrr were assessed. As expected, LIrr was found to be intact in young healthy volunteers after placebo. Furthermore, in the placebo condition P3b latency was decreased for target stimuli, which were pre-cued. This suggests that the predictability of the occurrence of these stimuli is mainly reflected by this ERP component. Biperiden had no effect on the behavioural LIrr measures, although prolonged reaction times were evident. Biperiden increased the N1 amplitude of the pre-exposed predictor letters, suggesting an effect of this drug on early perceptual processing. In conclusion, the within-subject paradigm used in the current study in combination with electroencephalography can reveal brain mechanisms involved in LIrr. M1 antagonism did not affect LIrr performance but seemed to influence early information processing.

Dynamics of anticipatory mechanisms during predictive context processing

We employed an electroencephalography paradigm manipulating predictive context to dissociate the neural dynamics of anticipatory mechanisms. Subjects either detected random targets or targets preceded by a predictive sequence of three distinct stimuli. The last stimulus in the three-stimulus sequence (decisive stimulus) did not require any motor response but 100% predicted a subsequent target event. We showed that predictive context optimises target processing via the deployment of distinct anticipatory mechanisms at different times of the predictive sequence. Prior to the occurrence of the decisive stimulus, enhanced attentional preparation was manifested by reductions in the alpha oscillatory activities over the visual cortices, resulting in facilitation of processing of the decisive stimulus. Conversely, the subsequent 100% predictable target event did not reveal the deployment of attentional preparation in the visual cortices, but elicited enhanced motor preparation mechanisms, indexed by an increased contingent negative variation and reduced mu oscillatory activities over the motor cortices before movement onset. The present results provide evidence that anticipation operates via different attentional and motor preparation mechanisms by selectively pre-activating task-dependent brain areas as the predictability gradually increases.

Alexithymia and the processing of emotional facial expressions (EFEs): systematic review, unanswered questions and further perspectives

Alexithymia is characterized by difficulties in identifying, differentiating and describing feelings. A high prevalence of alexithymia has often been observed in clinical disorders characterized by low social functioning. This review aims to assess the association between alexithymia and the ability to decode emotional facial expressions (EFEs) within clinical and healthy populations. More precisely, this review has four main objectives: (1) to assess if alexithymia is a better predictor of the ability to decode EFEs than the diagnosis of clinical disorder; (2) to assess the influence of comorbid factors (depression and anxiety disorder) on the ability to decode EFE; (3) to investigate if deficits in decoding EFEs are specific to some levels of processing or task types; (4) to investigate if the deficits are specific to particular EFEs. Twenty four studies (behavioural and neuroimaging) were identified through a computerized literature search of Psycinfo, PubMed, and Web of Science databases from 1990 to 2010. Data on methodology, clinical characteristics, and possible confounds were analyzed. The review revealed that: (1) alexithymia is associated with deficits in labelling EFEs among clinical disorders, (2) the level of depression and anxiety partially account for the decoding deficits, (3) alexithymia is associated with reduced perceptual abilities, and is likely to be associated with impaired semantic representations of emotional concepts, and (4) alexithymia is associated with neither specific EFEs nor a specific valence. These studies are discussed with respect to processes involved in the recognition of EFEs. Future directions for research on emotion perception are also discussed.

P3a from white noise

P3a and P3b event-related brain potentials (ERPs) were elicited with an auditory three-stimulus (target, distracter, and standard) discrimination task in which subjects responded only to the target. Distracter stimuli consisted of white noise or novel sounds with stimulus characteristics perceptually matched. Target/standard discrimination difficulty was manipulated by varying target/standard pitch differences to produce relatively easy, medium, and hard tasks. Error rate and response time increased with increases in task difficulty. P3a was larger for the white noise compared to novel sounds, maximum over the central/parietal recording sites, and did not differ in size across difficulty levels. P3b was unaffected by distracter type, decreased as task difficulty increased, and maximum over the parietal recording sites. The findings indicate that P3a from white noise is robust and should be useful for applied studies as it removes stimulus novelty variability. Theoretical perspectives are discussed.

Effect of complete stimulus predictability on P3 and N2 components: an electroencephalographic study

In everyday life one may encounter both unpredictable and self-initiated, hence anticipated, events. Here, we analyzed the effects of self-initiated auditory stimulus presentation on P3 and N2 components in an oddball paradigm. If the stimulus sequence was fully self-determined, both components were attenuated in comparison with computer-controlled representation. In contrast, both components were increased when only the stimulus onset was self-initiated, yet the forthcoming stimulus type was unknown. We hypothesize that predictive forward models offer an unifying explanation for the modulation of both P3 and N2 through: (a) attenuation of neuronal responses to anticipated stimuli contingent on one's own motor action and (b) enhancement of responses in case of incongruity between an anticipated action effect and the actual perceptual consequences.

Neural correlates of local contextual processing deficits in schizophrenic patients

Deficits in processing contextual information are one of the main features of cognitive dysfunction in schizophrenia, but the neurophysiologic substrate underlying this dysfunction is poorly understood. We used ERPs to investigate local contextual processing in schizophrenic patients. Local context was defined as the occurrence of a short predictive series of stimuli occurring before delivery of a target event. Response times of predicted targets were faster in controls compared to patients. Schizophrenia patients failed to generate the P3b latency shift between predicted and random targets that was observed in controls and demonstrated a prominent reduction of the peak of an early latency context dependent positivity. The current study provides evidence of contextual processing deficits in schizophrenia patients by demonstrating alteration in the behavioral and neural correlates of local contextual processing.