Examined Event-related Potentials Research Articles

Reduced P3b brain response during sustained visual attention is associated with remote blast mTBI and current PTSD in U.S. military veterans

Approximately 275,000 American service members deployed to Iraq or Afghanistan have sustained a mild traumatic brain injury (mTBI), with 75% of these incidents involving an explosive blast. Combat-related mTBI is frequently associated with comorbid mental health disorders, especially posttraumatic stress disorder (PTSD). Attention problems, including sustained attention, are common cognitive complaints of veterans with TBI and PTSD. The present study sought to examine neural correlates of sustained attention in veterans with blast mTBI and/or current PTSD. In 124 veterans of Operations Enduring and Iraqi Freedom (OEF/OIF), we examined event-related potentials (ERPs) elicited by targets and non-targets during performance of a degraded-stimulus continuous performance task (DS-CPT). Four groups, consisting of veterans with blast-related mTBI only, current PTSD only, both blast mTBI and PTSD, and a control group, were studied. Compared to all other groups, blast mTBI only participants were more likely to respond regardless of stimulus type during the DS-CPT. During target detection, the three mTBI/PTSD groups showed reduced amplitude of the P3b (i.e., P300) ERP at Pz compared to the control group. P3b of the three affected groups did not differ from each other. These results suggest that parietal P3b amplitude reduction during target detection in the DS-CPT task may be an index of brain pathology after combat trauma, yet the diminished brain response fails to differentiate independent effects of blast-related mTBI or severity of PTSD symptomatology.

Enhanced auditory spatial performance using individualized head-related transfer functions: An event-related potential study.

This study examined event-related potential (ERP) correlates of auditory spatial benefits gained from rendering sounds with individualized head-related transfer functions (HRTFs). Noise bursts with identical virtual elevations (0°-90°) were presented back-to-back in 5-10 burst "runs" in a roving oddball paradigm. Detection of a run's start (i.e., elevation change detection) was enhanced when bursts were rendered with an individualized compared to a non-individualized HRTF. ERPs showed increased P3 amplitudes to first bursts of a run in the individualized HRTF condition. Condition differences in P3 amplitudes and behavior were positively correlated. Data suggests that part of the individualization benefit reflects post-sensory processes.

Electrophysiological correlates of the cognitive control processes underpinning mixing and switching costs

Typically, in task-switching contexts individuals are slower and less accurate when repeating a task in mixed blocks compared to single-task blocks (mixing cost) and when switching to a new task compared to repeating a previous one (switch cost). Previous research has shown that distinct electrophysiological correlates underlie these two phenomena. However, this evidence is not a consistent result. The goal of this study was to better characterize differences between the control processes involved in mixing and switch costs. To this aim, we examined event-related potentials (ERPs) evoked during a cued task-switching experiment. In order to minimize the confounding effects of cognitive demands unrelated to task-switching, we asked participants to shift between two simple tasks (a letter identity task and a letter position task). The mixing cost was defined, in terms of ERPs, by contrasting repeat and single-task trials, whereas the ERP switch cost was obtained from the comparison of switch and repeat trials. Cue-locked ERPs showed that the mixing cost was mediated by two sustained components, an early posterior positivity and a late anterior negativity. On the other hand, the switch cost was associated with two early phasic positive components, one principally distributed over centro-parietal sites and the other located over left posterior sites. In target-locked ERPs the mixing cost was expressed by a frontal positivity, whereas the switch cost was expressed by a reduced parietal P3b. Overall, the results extend previous findings by providing elucidating ERP evidence on distinct proactive and reactive control processes involved in mixing and switch costs.

Principal components of electrocortical activity during self-evaluation indicate depressive symptom severity.

Negative self-evaluation is an important psychological characteristic of depression. In order to study the underlying neural mechanisms, we examined event-related potentials (ERPs) during a self-evaluation task in a community sample (N = 150) of adults reporting a range of depressive symptoms. Principal components analysis (PCA) was used to separate processes that overlap in the average ERP, and neural source analysis was applied to localize the ERP components, with a particular focus on the frontal networks that are thought to be critical to affective self-regulation in depression. Consistent with previous research, individuals reporting greater depression showed enhanced negativity over medial frontal regions as well as attenuation of the late positive potential over parietal regions. Examining loadings of frontal sources on the ERP components showed that activity in the right inferior frontal region may be particularly important for depressed individuals: activity in this region declined as symptoms became more severe. Characterizing brain mechanisms of self-evaluation on the timescale of cognitive events may provide insight into the neural mechanisms of self-regulation that are important in cognitive therapy, and that could be made more amenable to change through increasing neuroplasticity with targeted non-invasive neuromodulation.

Enhanced Early Posterior Negativity to Fearful Faces in Patients with Anxiety Disorder.

Patients with anxiety disorders (AnDs) have distinct patterns of threat-related emotional processing compared to healthy controls (HCs). The current study investigated the temporal course of emotional processing in AnDs by examining Event-related potential (ERP) components. Twenty-three AnDs and twenty-four age- and gender-matched HCs viewed emotional (fearful, happy) and neutral faces while their electroencephalograms were recorded. Early (P100, N170), middle (early posterior negativity; EPN), and late ERP components late positive potential were analyzed. To localize ERP source activity, standardized low-resolution brain electromagnetic tomography (sLORETA) was used. AnDs displayed significantly enhanced mean amplitude of the EPN compared to HCs when fearful faces were presented. In addition, the EPN's mean amplitude elicited by fearful faces was more pronounced than for happy and neutral faces in AnDs, whereas in HCs the EPN elicited by fearful faces was only augmented compared to neutral faces. Finally, sLORETA analysis revealed that the source activity of the EPN (fearful minus happy face condition) was increased in the cuneus and precuneus in AnDs compared to HCs. Our results indicate that the EPN is a distinct ERP component modulated by facial emotional processing in AnDs. Furthermore, the results show that anxiety symptoms enhance selective attention for fearful faces. Finally, it revealed that the cuneus and precuneus are involved in fearful face processing in AnDs.

Chronic cannabis use and ERP correlates of visual selective attention during the performance of a flanker go/nogo task

The aim of the study was to investigate the relationship between chronic cannabis use and visual selective attention by examining event-related potentials (ERPs) during the performance of a flanker go/nogo task. Male participants were 15 chronic cannabis users (minimum two years use, at least once per week) and 15 drug naive controls. Cannabis users showed longer reaction times compared to controls with equivalent accuracy. Cannabis users also showed a reduction in the N2 ‘nogo effect’ at frontal sites, particularly for incongruent stimuli, and particularly in the right hemisphere. This suggests differences between chronic cannabis users and controls in terms of inhibitory processing within the executive control network, and may implicate the right inferior frontal cortex. There was also preliminary evidence for differences in early selective attention, with controls but not cannabis users showing modulation of N1 amplitude by flanker congruency. Further investigation is required to examine the potential reversibility of these residual effects after long-term abstinence and to examine the role of early selective attention mechanisms in more detail.

Do classifiers make the syntactic count/mass distinction? Insights from ERPs in classifier processing in Japanese

Abstract It has long been assumed that classifier languages lack syntactic distinctions of objects and substances (i.e., count/mass distinction; Allan, 1977; Chierchia, 1998; Krifka, 1995; Lucy, 1992; Quine, 1969). Several linguists, however, claimed that classifier languages also make the syntactic count/mass distinction through the selective use of count classifiers (i.e., sortal classifiers) and mass classifiers (e.g., Cheng & Sybesma, 1998, 1999). The present study examined whether Japanese speakers make a syntactic count/mass distinction using the classifier system. The electroencephalogram (EEG) was recorded while Japanese speakers read word pairs (Experiment 1) or sentences (Experiment 2) in which noun–classifier agreement relations were manipulated. We examined event-related potentials (ERPs) elicited by the within-count/mass-category violation (e.g., an object name accompanied by a classifier for other objects) and the across-count/mass-category violation (e.g., an object name accompanied by a classifier for substances). In both experiments, the violation of the noun–classifier agreements elicited the N400, regardless of whether the noun–classifier disagreement was made within or across the ontological object/substance boundary. The across-count/mass-category violation did not recruit a syntactic process in the brain, suggesting that the Japanese classifier system does not highlight the distinction between objects and substances. The results also indicated that the processing of Japanese numeral classifiers is primarily semantic-based.

Altered Neural Activity during Semantic Object Memory Retrieval in Amnestic Mild Cognitive Impairment as Measured by Event-Related Potentials.

Deficits in semantic memory in individuals with amnestic mild cognitive impairment (aMCI) have been previously reported, but the underlying neurobiological mechanisms remain to be clarified. We examined event-related potentials (ERPs) associated with semantic memory retrieval in 16 individuals with aMCI as compared to 17 normal controls using the Semantic Object Retrieval Task (EEG SORT). In this task, subjects judged whether pairs of words (object features) elicited retrieval of an object (retrieval trials) or not (non-retrieval trials). Behavioral findings revealed that aMCI subjects had lower accuracy scores and marginally longer reaction time compared to controls. We used a multivariate analytical technique (STAT-PCA) to investigate similarities and differences in ERPs between aMCI and control groups. STAT-PCA revealed a left fronto-temporal component starting at around 750 ms post-stimulus in both groups. However, unlike controls, aMCI subjects showed an increase in the frontal-parietal scalp potential that distinguished retrieval from non-retrieval trials between 950 and 1050 ms post-stimulus negatively correlated with the performance on the logical memory subtest of the Wechsler Memory Scale-III. Thus, individuals with aMCI were not only impaired in their behavioral performance on SORT relative to controls, but also displayed alteration in the corresponding ERPs. The altered neural activity in aMCI compared to controls suggests a more sustained and effortful search during object memory retrieval, which may be a potential marker indicating disease processes at the pre-dementia stage.

Electrophysiology of facilitation priming in obsessive–compulsive and panic disorders

ObjectiveRepeated experience with stimuli often primes faster, more efficient neuronal and behavioural responses. Exaggerated repetition priming effects have previously been reported in obsessive–compulsive disorder (OCD), however little is known of their underlying neurobiology or disorder-specificity, hence we investigated these factors. MethodsWe examined event-related potentials (ERPs) and behaviour while participants with OCD, panic disorder and healthy controls (20 per group) performed a Go/NoGo task which manipulated target repetition sequences. ResultsBoth clinical groups showed stronger reaction time (RT) priming than HCs, which in OCD was greater in a checking, than washing, subgroup. Both clinical groups had similar RT deficits and ERP anomalies across several components, which correlated with psychopathology and RT priming. In OCD alone, N1 latency tended to increase to repeated stimuli, correlated with O–C symptoms, whereas it decreased in other groups. OCD-checkers had smaller target P2 amplitude than all other groups. ConclusionsEnhanced neural priming is not unique to OCD and may contribute to salient sensory-cognitive experiences in anxiety generally. These effects are related to symptom severity and occur to neutral stimuli and in the context of overall RT impairment, suggesting they may be clinically relevant and pervasive. The results indicate overlapping information-processing and neurobiological factors across disorders, with indications of OCD-specific trends and subgroup differences. SignificanceThis first electrophysiological investigation of OCD priming in OCD to include anxious controls and OCD subgroups allows for differentiation between overlapping and OCD-specific phenomena, to advance neurobiological models of OCD.

The Effect of Emotional Conflict on Attention Allocation: An Event-Related Potential Study

Attention allocation research frequently focuses on the valence of emotion. However, there is increasing evidence to indicate that arousal may be more relevant at some stages of affective processing. The present study employed a combined priming and cue-target paradigm and examined event-related potentials (ERPs) in order to explore the effects of emotional conflict of arousal on attention allocation. The background context of arousal was manipulated (using photos of facial expressions) while subjects performed a cognitive task in which a central arrow cue indicated the location of a peripheric target square, and a response was made according to the direction of the square. There was no main effect between incongruent emotion and congruent emotion in the response time, which means the resolution of the emotional conflict facilitate the participant behavioral response. There was a main effect of different emotional states on ERP component. In the present study, incongruent arousal also triggered greater positive potential compared with congruent arousal.

At will or not at will: Electrophysiological correlates of preparation for voluntary and instructed task-switching paradigms.

The present study investigated whether the advanced reconfiguration processes of the voluntary switching (VTS) paradigm were different from those of the instructed task switching (ITS) paradigm by examining event-related potentials (ERPs) in a within-subjects design. Of importance, given that effector-to-task mapping might lead to differential preparatory strategies, two effector-to-task mapping groups were studied: the hand-to-task (HAND) and finger-to-task (FINGER) groups. Intriguingly, we found the increased posterior negativity for voluntary switch (and/or increased posterior positivity for voluntary repeat) was exclusive to the HAND group, whereas the increased switch-related late posterior positivity in the ITS paradigm was independent of the effector manipulation. Moreover, the lateralized readiness potentials (LRP) and the mu and beta motor-related amplitude asymmetries indicated that the differential switch-related modulations were not the byproduct of hand-specific preparation. The advanced preparatory strategies in the VTS and ITS paradigms are discussed.

Examining Event-Related Potential (ERP) correlates of decision bias in recognition memory judgments.

Memory judgments can be based on accurate memory information or on decision bias (the tendency to report that an event is part of episodic memory when one is in fact unsure). Event related potentials (ERP) correlates are important research tools for elucidating the dynamics underlying memory judgments but so far have been established only for investigations of accurate old/new discrimination. To identify the ERP correlates of bias, and observe how these interact with ERP correlates of memory, we conducted three experiments that manipulated decision bias within participants via instructions during recognition memory tests while their ERPs were recorded. In Experiment 1, the bias manipulation was performed between blocks of trials (automatized bias) and compared to trial-by-trial shifts of bias in accord with an external cue (flexibly controlled bias). In Experiment 2, the bias manipulation was performed at two different levels of accurate old/new discrimination as the memory strength of old (studied) items was varied. In Experiment 3, the bias manipulation was added to another, bottom-up driven manipulation of bias induced via familiarity. In the first two Experiments, and in the low familiarity condition of Experiment 3, we found evidence of an early frontocentral ERP component at 320 ms poststimulus (the FN320) that was sensitive to the manipulation of bias via instruction, with more negative amplitudes indexing more liberal bias. By contrast, later during the trial (500–700 ms poststimulus), bias effects interacted with old/new effects across all three experiments. Results suggest that the decision criterion is typically activated early during recognition memory trials, and is integrated with retrieved memory signals and task-specific processing demands later during the trial. More generally, the findings demonstrate how ERPs can help to specify the dynamics of recognition memory processes under top-down and bottom-up controlled retrieval conditions.

Late, not early mismatch responses to changes in frequency are reduced or deviant in children with dyslexia: an event-related potential study.

BackgroundDevelopmental disorders of oral and written language have been linked to deficits in the processing of auditory information. However, findings have been inconsistent, both for behavioural and electrophysiological measures.MethodsIn this study, we examined event-related potentials (ERPs) in 20 6- to 14-year-old children with developmental dyslexia and 20 age-matched controls, divided into younger (6–11 years, n = 10) and older (11–14 years, n = 10) age bands. We focused on early (mismatch negativity; MMN) and late (late discriminative negativity; LDN) conventional mismatch responses and associated measures derived from time-frequency analysis (inter-trial coherence and event-related spectral perturbation). Responses were elicited using an auditory oddball task, whereby a stream of 1000-Hz standards was interspersed with rare large (1,200 Hz) and small (1,030 Hz) frequency deviants.ResultsConventional analyses revealed no significant differences between groups in the size of the MMN to either large or small frequency deviants. However, the younger age band of children with dyslexia showed an enhanced inter-trial coherence in the theta frequency band over the time window corresponding to the MMN to small deviants. By contrast, these same children showed a reduced-amplitude LDN for the small deviants relative to their age-matched controls, whilst the older children with dyslexia showed a shorter and less intense period of event-related desynchronization over this time window.ConclusionsInitial detection and discrimination of auditory frequency change appears normal or even enhanced in children with dyslexia. Rather, deficits in late-stage auditory processing appear to be a feature of this population.

Culture Modulates Perceptual Attention: An Event-Related Potential Study

Previous work shows that European Americans are more likely than Asians to focus their attention on a central object. The authors investigated the time course of this cultural difference by examining event-related potentials (ERPs) as participants tried to detect a low-frequency target (an image of a coffee mug) embedded in a series of standard stimuli (animal images). The authors identified a reliable cultural difference as early as 200 ms posttarget, with a significantly larger negativity at the frontal region of the brain (called N2; indicative of early orienting) for European Americans than for Asian Americans. Furthermore, a slow wave component starting around 700 ms posttarget (indicative of elaborative processing) was also larger for European Americans than for Asian Americans. Together, the current evidence suggests that as compared to Asians, European Americans allocate more attention to a goal-relevant object from the very beginning of stimulus processing. Implications for social vision are disc...

Neurocognitive, psychological and behavioral correlates of binge drinking and use of alcohol with caffeinated beverages in college-aged adults

Background: We examined event-related potential (ERP), behavioral and psychological correlates of binge drinking and the use of alcohol mixed with caffeinated beverages (AmCBs) in college-aged (18–26 years) adults. Objective: Our objective was to delineate the neurocognitive correlates of different patterns of risky alcohol use in this population. Methods: We collected ERP data while an initial sample of 60 participants completed visual oddball and go/no-go tasks. We also collected self-report data measuring levels of sensation seeking, impulsivity, and drinking-induced disinhibition. In our primary analyses between binge drinker (N = 17) and comparison participants (N = 29), we used analysis of covariance (ANCOVA) to control for monthly marijuana usage and excluded participants who reported using other illicit drugs. As separate, exploratory analyses, we compared participants who reported using AmCBs (n = 14) and those who did not (n = 46), co-varying for monthly marijuana and recreational drug use. Results: We found that binge drinkers and AmCB users reported significantly higher levels of sensation seeking and drinking-induced disinhibition. In addition, we found that binge drinkers exhibited greater P3a/b amplitudes in the oddball task. In contrast, AmCB users exhibited significantly attenuated P3a amplitudes to distracter stimuli in the oddball task. However, we found no statistically significant differences in the amplitudes of P2(00) or N2(00) components between binge drinkers and comparison participants or between AmCB users and nonusers. Conclusions: Overall, these data suggest that binge drinking and AmCB use are associated with P3 alterations, but the specific effects may differ for individuals with different patterns of risky alcohol use.

Aberrant N400 responses to phonological overlap during rhyme judgements in children at risk for dyslexia

It is widely accepted that dyslexia is associated with difficulties in phonological awareness and that rhyme awareness in young children can predict later reading success. However, little is known regarding the underlying phonological mechanisms of rhyme awareness in dyslexia, as rhyme awareness is typically assessed using explicit behavioural measures that represent only the endpoint of processing and often lack phonological distracters. We examined event-related potentials (ERPs) in response to auditory word pairs that differed in phonological overlap during a rhyme judgement task given to 6-year-old beginning readers who were at risk for dyslexia (n=30) and typical-reading age-matched controls (n=29). ERPs were recorded in response to word pairs with various types of phonological overlap, including rhyming (e.g., wall-ball), non-rhyming overlapping (e.g., bell-ball) and non-rhyming unrelated (e.g., sock-ball) word pairs. Both groups of participants exhibited N400 responses for basic rhyme judgements vs. unrelated targets. In the typical-reading controls, the neural responses also differed between the rhyming targets and the non-rhyming overlapping targets, whereas neural responses to these targets were similar in the group of children at risk for dyslexia, indicating difficulties in their ability to process similar-sounding, non-rhyming targets. These findings suggest that typical-reading children solve the rhyme judgement task using a more analytical approach, whereas children who are at risk for dyslexia base their judgments on a comparison of overall sound similarity.

Event-related potential index of age-related differences in memory processes in adults with Down syndrome

A major goal of aging research is to identify early markers of age-related cognitive decline. Persons with Down syndrome (DS) experience accelerated aging and high risks for dementia, making them a valuable albeit understudied model for testing such markers. This study examined event-related potential (ERP) indices of visual memory in younger (19–25 years) and older (35–40 years) adults with DS using a passive viewing paradigm that did not require memorization or behavioral responses. ERPs were recorded in response to unfamiliar urban and nature scenes, with some images presented once and others repeated multiple times. Within 600 to 900 milliseconds after stimulus onset, repeated stimuli elicited more positive amplitudes in younger participants, indicating stimilus recognition. ERPs of older adults did not show such increases, suggesting reduced memory functioning. ERP indices were unrelated to participants' intellectual functioning, but did correlate with age and caregiver-reported lethargy/withdrawal behaviors. Passive ERP measures of memory processes are sensitive to early stages of cognitive decline in DS and are promising markers of cognitive risk for future aging studies.

Neural processing stages during object-substitution masking and their relationship to perceptual awareness

The extent of visual perceptual processing that occurs in the absence of awareness is as yet unclear. Here we examined event-related-potential (ERP) indices of visual and cognitive processes as awareness was manipulated through object-substitution masking (OSM), an awareness-disrupting effect that has been hypothesized to result from the disruption of reentrant signaling to low-level visual cortical areas. In OSM, a visual stimulus array is briefly presented that includes a parafoveal visual target denoted by a cue, typically consisting of several surrounding dots. When the offset of the target-surrounding cue dots is delayed relative to the rest of the array, a striking reduction in the perception of the target image surrounded by the dots is observed. Using faces and houses as the target stimuli, we found that successful OSM reduced or eliminated all the measured electrophysiological indices of visual processing stages after 130ms post-stimulus. More specifically, when targets were missed within the masked condition (i.e., on trials with effective OSM that disrupted awareness), we observed fully intact early feed-forward processing up through the visual extrastriate P1 ERP component peaking at 100ms, followed by reduced low-level activity over the occipital pole 130–170ms post-stimulus, reduced ERP indices of lateralized shifts of attention toward the parafoveal target, reduced object-generic visual processing, abolished object-category-specific (face-specific) processing, and reduced late visual short-term-memory processing activity. The results provide a comprehensive electrophysiological account of the neurocognitive underpinnings of effective OSM of visual-object images, including evidence for central roles of early reentrant signal disruption and insufficient visual attentional deployment.

An ERP study of structural anomalies in native and semantic free artificial grammar: Evidence for shared processing mechanisms

Artificial grammars have been widely applied to the study of sequential learning in language, but few studies have directly compared the neural correlates of artificial and native grammar processing. In this study, we examined Event Related Potentials (ERPs) elicited by structural anomalies in semantic-free artificial grammar sequences and sentences in the subjects’ native language (Spanish). Although ERPs differed during early stages, we observed similar posterior negativities (N400) and P600 effects in a late stage. We interpret these results as evidence of at least partially shared neural mechanisms for processing of language and artificial grammars. We suggest that in both the natural and artificial grammars, the N400 and P600 components we observed can be explained as the result of unfulfilled predictions about incoming stimuli.

Global visual processing decreases with autistic‐like traits: A study of early lateralized potentials with spatial attention

AbstractExtensive research suggests that autistic individuals have deficits in global visual processing that may cause an attentional bias toward local details. This tendency has also been noted in nonclinical samples with high autistic‐like traits, as measured using the autism‐spectrum quotient (AQ). However, as top‐down attention as an executive control can modulate early visual processing, it is still unclear whether this local processing bias is due to atypicality in bottom‐up processing or a top‐down attentional set. The present study explored this issue by examining event‐related potentials (ERPs) in a sustained focal‐attention task that involved bilateral stimulus arrays. In this task, a P1 spatial attention effect (at approximately 100–150 ms post‐stimulus) reflects top‐down attentional modulation of incoming sensory processing, and an N1 attention effect (150–200 ms) reflects obligatory attention‐spreading based on perceptual grouping. The results showed that AQ scores were negatively correlated with the N1 attention effects for conditions in which bilateral stimuli were grouped with feature similarity and amodal completion. This finding supports the view that bottom‐up processing in perceptual organization varies with autism spectrum.