Differences In Event-related Potentials Research Articles

Targets and non-targets in the aging brain: A go/nogo event-related potential study

This study tested whether older adults show enhanced suppression of inappropriate processing of non-target information, as marked with the nogo-P3 event-related potential (ERP). Healthy younger and older adults were tested on a simple go/nogo task with visually presented numbers. Unlike in most of the previous studies, go and nogo stimuli were matched for frequency and conflict level in order to minimize the impact of task difficulty, probability monitoring, or conflict detection and resolution on the age-related ERP differences. Older adults showed slower go responses but a comparable accuracy to younger controls. The parietal go-P3 latency was also delayed with aging, while the central nogo-P3 was more pronounced in older adults than in younger controls. The amplitude of this component negatively correlated with go-RTs. In line with previous studies, this suggests that a partial response preparation to nogo events is strongly suppressed in older adults, especially faster ones.

Developmental gender differences in the synchronization of auditory event-related oscillations

Objectives The aim of the present study was to explore the neurophysiologic origins of gender differences in auditory processing mechanisms of 7–10 year-old children by means of event-related oscillations. It was tested if the developmental changes in synchronization and magnitude of oscillations in different processing conditions depended on gender. Methods Eighteen girls and 18 boys aged 7–10 years were pair wise matched for age and were divided into two age groups. Auditory event-related potentials (ERPs) were recorded in passive, sensorimotor and working memory conditions. Phase-locking and single-trial magnitude of ERPs were analyzed in the delta (0.5–4 Hz), theta (4–7 Hz), slow (7–10 Hz), and fast (10–14 Hz) alpha frequency bands to test the effects of gender, age, and processing condition. Results The phase-locking of auditory delta, theta, and slow alpha oscillations increased with development only in girls, independently of task processing. Only for the theta phase-locking was this effect additionally affected by the motor-related task. No changes in the magnitude of oscillations accompanied these gender differences in synchronization except for parietal delta responses that also increased with development only in girls. Conclusions The results demonstrate that gender differences in auditory ERPs basically originate from a stronger functional synchronization of oscillatory responses generated during stimulus processing. Significance The study provides evidence that the functional maturation of oscillatory auditory networks reflected by a progressive developmental increase of synchronization, is accelerated in girls relative to boys between 7 and 10 years of age.

Newborn brain event-related potentials revealing atypical processing of sound frequency and the subsequent association with later literacy skills in children with familial dyslexia

The role played by an auditory-processing deficit in dyslexia has been debated for several decades. In a longitudinal study using brain event-related potentials (ERPs) we investigated 1) whether dyslexic children with familial risk background would show atypical pitch processing from birth and 2) how these newborn ERPs later relate to these same children’s pre-reading cognitive skills and literacy outcomes. Auditory ERPs were measured at birth for tones varying in pitch and presented in an oddball paradigm (1100Hz, 12%, and 1000Hz, 88%). The brain responses of the typically reading control group children (TRC group, N=25) showed clear differentiation between the frequencies, while those of the group of reading disability with familial risk (RDFR, 8 children) and the group of typical readers with familial risk (TRFR, 14 children) did not differentiate between the tones. The ERPs of the latter two groups differed from those of the TRC group. However, the two risk groups also showed a differential hemispheric ERP pattern. Furthermore, newborn ERPs reflecting passive change detection were associated with phonological skills and letter knowledge prior to school age and with phoneme duration perception, reading speed (RS) and spelling accuracy in the 2nd grade of school. The early obligatory response was associated with more general pre-school language skills, as well as with RS and reading accuracy (RA). Results suggest that a proportion of dyslexic readers with familial risk background are affected by atypical auditory processing. This is already present at birth and also relates to pre-reading phonological processing and speech perception. These early differences in auditory processing could later affect phonological representations and reading development. However, atypical auditory processing is unlikely to suffice as a sole explanation for dyslexia but rather as one risk factor, dependent on the genetic profile of the child.

Inhibition dysfunction in depression: Event-related potentials during negative affective priming

The study aimed to investigate whether depressed patients show impairment of valence-dependent inhibition and its neurophysiological correlates. Event-related potentials (ERPs) were collected from 18 patients with unipolar depression and 18 normal controls during an affective negative priming task. A less effective inhibition in patients was specific for negative information. These behavioral effects were paralleled by ERP differences. In addition to the overall reduced P2 amplitude for negative trials and the overall reduced late positive component (LPC) amplitude for positive and negative trials in patients, ERP differences in different conditions for each group were also found. The patients showed reduced central-parietal P2 amplitude and shorter LPC latency in response to negative experimental targets, whereas the controls showed larger left central P2 amplitude and delayed LPC latency in response to negative experimental targets. No such effects were found for positive targets. These results suggest that the inhibition dysfunction of negative affect influences the earlier attention allocation stage and the later evaluation stage in depressed patients.

ERP differences of pre-lexical processing between dyslexic and non-dyslexic children

The present Event-Related Potential (ERP) study aimed to investigate group differences in the early processing stages of 36 dyslexic and 24 non-dyslexic 8–12 year old children performing a lexical decision (word/pseudoword judgment) task. Our data showed larger amplitudes of negative-going waveforms in non-dyslexic children than dyslexic children over occipital/occipitotemporal electrodes at about 220 ms after stimulus onset. This electrophysiological response has previously been identified in adult readers and labeled as the N170 component. Notably, as reflected by the topographic maps children irrespective of group processed the linguistic stimuli bilaterally and we did not observe any differences in ERP parameters in words and pseudowords within groups. Contrarily, behavioral responses indicate that words were more quickly recognized than pseudowords irrespective of group. By applying post-hoc ROI analyses based on a source estimation approach (sLORETA) we observed that non-dyslexic participants, when compared to dyslexic children, demonstrated significantly stronger current density over the left hemispheric inferior temporal lobe when processing pseudowords. We concluded that impaired reading is reflected by the decreased amplitude of the early lexical component N170. The lack of a left hemispheric processing preference in both groups and similar activation for words and pseudowords can be considered a lack of reading experience and less established reading system in children. Our results indicate that dyslexic children commit fewer specialized neuronal circuits for processing print and confirm the reasoning that acquiring reading skills requires cortical reorganization over occipitotemporal regions.

A high-density ERP study reveals latency, amplitude, and topographical differences in multiple sclerosis patients versus controls

To quantify latency, amplitude and topographical differences in event-related potential (ERP) components between multiple sclerosis (MS) patients and controls and to compare ERP findings with results from the paced auditory serial addition test (PASAT). Fifty-four subjects (17 relapsing remitting (RRMS) patients, 16 secondary progressive (SPMS) patients, and 21 controls) completed visual and auditory oddball tasks while data were recorded from 134 EEG channels. Latency and amplitude differences, calculated using composite mean amplitude measures, were tested using an ANOVA. Topographical differences were tested using statistical parametric mapping (SPM). In the visual modality, P2, P3 amplitudes and N2 latency were significantly different across groups. In the auditory modality, P2, N2, and P3 latencies and N1 amplitude were significantly different across groups. There were no significant differences between RRMS and SPMS patients on any ERP component. There were topographical differences between MS patients and controls for both early and late components for the visual modality, but only in the early components for the auditory modality. PASAT score correlated significantly with auditory P3 latency for MS patients. There were significant ERP differences between MS patients and controls. The present study indicated that both early sensory and later cognitive ERP components are impaired in MS patients relative to controls.

Temporal Dynamics of Memory-Related Effects in Older and Young Adults: An Event-Related Potential Study

Priming effects on the identification process were examined in young and older adults by using event-related potentials (ERPs). Animals and artifacts were presented in an ascending sequence of filtered images, half of which had been shown in their complete versions in a previous study phase. Each stimulus was represented by a progressively less filtered image (i.e., more complete) until the whole version was revealed in a sequence of frames. Such a paradigm allowed us to record ERPs prior to, and during, the identification of stimuli. Results showed a dynamic interplay between memory, category, and aging effects. At the moment of identification, young adults elicited larger positivity at parietal sites for previously studied stimuli and this effect was not observed for older adults. For stimuli previously studied, a striking effect was observed in both groups at the level just prior to overt identification. In addition, a frontally distributed priming effect was evident in the elderly. Category-related ERP differences emerged between the two age groups. In particular, younger participants elicited an early positive activation at anterior sites upon seeing stimuli of animals. These results are discussed in relation to current models of recognition memory, categorization, and age-related cognitive decline.

The time course of novelty processing in sensation seeking: An ERP study

Novelty processing is critical for human survival in a rapidly changing environment. However, how and when the orientation attention reflected by novelty processing is modulated by personality elements such as sensation seeking is still opened. The present study investigated the time course of novelty processing in sensation seeking by recording the event-related potentials (ERPs) in a visual novelty oddball task. High and low sensation seekers performed a visual oddball task, in which participants were instructed to detect an inverted triangle (target) and ignore both upright triangle (standard) and unrepeated line drawings of pseudo-objects deviant from participants' long-term memory (novelty). While there were no group differences in ERPs to standard and target stimuli, ERPs to novel stimuli showed a strong modulation by sensation seeking trait. The low sensation seekers, compared with the high sensation seekers, exhibited an increased N2 to novel stimuli at frontal sites. Moreover, the Pd3 component reflecting purely novelty processing was enhanced and less habituated in the high sensation seeking participants. The current findings implicated that low sensation seekers showed sensitivity to novelty detection, whereas high sensation seekers displayed stronger and more sustained novelty appraisal.

Should I Stay or Should I Go? Neural Basis of Between-Trial Adjustments in the Stop-signal Task

Event Abstract Back to Event Should I Stay or Should I Go? Neural Basis of Between-Trial Adjustments in the Stop-signal Task R T Knight1, 2, U M Krämer1, 3* and T F Münte3, 4 1 University of California, Helen Wills Neuroscience Institute, United States 2 University of California, Department of Psychology, United States 3 Otto-von-Guericke-University, Dept. of Neuropsychology, Germany 4 Center for Behavioral Brain Sciences, Germany The ability to adjust behavior after errors is an essential cognitive control mechanism, which has traditionally been assigned to prefrontal cortical regions. Yet, we still know little about the neurophysiological dynamics of these control mechanisms. Previous research suggested inhibitory processes as underlying mechanism of post-error slowing. Here, we studied between-trial adjustments in the stop-signal task by means of event-related potentials (ERPs) and oscillatory brain activity. In the stop-signal task, participants perform in a choice reaction time task and are asked to suppress any response whenever a stop-signal is presented shortly after the target stimulus. We looked at the time-course of neural activity during sequences of successful or errorful stop-trials and the following go-trials. We were especially interested in the N2 as index of response inhibition and in oscillatory dynamics, particularly in the motor-related alpha and beta bands. On the behavioral level, we observed slower reaction times both after successful and unsuccessful inhibitions. Neurophysiological correlates of these behavioral adjustments were apparent both before onset of the next target stimulus and during response preparation in the following go-trial. Moreover, ERP differences between post-error and post-inhibition trials were suggestive of distinct neural processes underlying the behavioral adaptations in these trials. Conference: The 20th Annual Rotman Research Institute Conference, The frontal lobes, Toronto, Canada, 22 Mar - 26 Mar, 2010. Presentation Type: Poster Presentation Topic: Cognitive Neuroscience Citation: Knight R, Krämer U and Münte T (2010). Should I Stay or Should I Go? Neural Basis of Between-Trial Adjustments in the Stop-signal Task. Conference Abstract: The 20th Annual Rotman Research Institute Conference, The frontal lobes. doi: 10.3389/conf.fnins.2010.14.00112 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 29 Jun 2010; Published Online: 29 Jun 2010. * Correspondence: U M Krämer, University of California, Helen Wills Neuroscience Institute, Berkeley, United States, ukraemer@berkeley.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers R T Knight U M Krämer T F Münte Google R T Knight U M Krämer T F Münte Google Scholar R T Knight U M Krämer T F Münte PubMed R T Knight U M Krämer T F Münte Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Neurophysiological evidence for the influence of past experience on figure–ground perception

A fundamental aspect of perceptual organization entails segregating visual input into shaped figures presented against shapeless backgrounds; an outcome termed "figure-ground perception" or "shape assignment." The present study examined how early in processing past experience exerts an influence on shape assignment. Event-related potential (ERP) measures of brain activity were recorded while observers viewed silhouettes of novel objects that differed in whether or not a familiar shape was suggested on the outside-the groundside-of their bounding edges (experimental versus control silhouettes, respectively). Observers perceived both types of silhouettes as novel shapes and were unaware of the familiar shape suggested on the groundside of experimental silhouettes. Nevertheless, we expected that the familiar shape would be implicitly identified early in processing and would compete for figural status with the novel shape on the inside. Early (106-156 ms) ERPs were larger for experimental silhouettes than for control silhouettes lacking familiarity cues. The early ERP difference occurred during a time interval within which edge-segmentation-dependent response differences have been observed in previous neurophysiological investigations of figure-ground perception. These results provide the first neurophysiological evidence for an influence of past experience during the earliest stages of shape assignment.

Are Females More Responsive to Emotional Stimuli? A Neurophysiological Study Across Arousal and Valence Dimensions

Men and women seem to process emotions and react to them differently. Yet, few neurophysiological studies have systematically investigated gender differences in emotional processing. Here, we studied gender differences using Event Related Potentials (ERPs) and Skin Conductance Responses (SCR) recorded from participants who passively viewed emotional pictures selected from the International Affective Picture System (IAPS). The arousal and valence dimension of the stimuli were manipulated orthogonally. The peak amplitude and peak latency of ERP components and SCR were analyzed separately, and the scalp topographies of significant ERP differences were documented. Females responded with enhanced negative components (N100 and N200), in comparison to males, especially to the unpleasant visual stimuli, whereas both genders responded faster to high arousing or unpleasant stimuli. Scalp topographies revealed more pronounced gender differences on central and left hemisphere areas. Our results suggest a difference in the way emotional stimuli are processed by genders: unpleasant and high arousing stimuli evoke greater ERP amplitudes in women relatively to men. It also seems that unpleasant or high arousing stimuli are temporally prioritized during visual processing by both genders.

Visual mismatch negativity to irrelevant changes is sensitive to task-relevant changes

Event-related potentials (ERPs) were measured in response to frequent (standard) and infrequent (deviant) task-irrelevant bar patterns. The constituent bars of the deviant patterns had either different orientation or different color than the bars of the standard. The task was the detection of either the orientation or the color change of a centrally presented shape. The deviant minus the standard ERP difference produced posterior negativity and was identified as visual mismatch negativity (vMMN). On the one hand, vMMN to orientation deviancy had smaller amplitude in the task demanding detection of the orientation change, and vMMN to color deviancy had smaller amplitude in the task demanding the color change. On the other hand, irrelevant deviancy influenced the task-performance. Reaction time (RT) to the orientation change of the target shape was longer in sequences with orientation change in the background, whereas RT to color change was longer in sequences with color change in the background. This interaction suggested that there was competition between the processing of irrelevant stimuli that share characteristics of task-related changes and target-related processing.

Newborn Event-Related Potentials Predict Poorer Pre-Reading Skills in Children at Risk for Dyslexia

Earlier results from the Jyväskylä Longitudinal Study of Dyslexia showed that newborn event-related potentials (ERPs) of children with and without familial risk for dyslexia were associated with receptive language and verbal memory skills between 2.5 and 5 years of age. We further examined whether these ERPs (responses to synthetic consonant-vowel syllables /ba/, /da/, /ga/; presented equiprobably with 3,910—7,285 ms interstimulus intervals) predict later pre-reading skills measured before the onset of school (6.5 years of age). In line with our earlier results, the at-risk children (N = 11) with atypical speech processing in the right hemisphere (a slower shift in polarity from positivity to negativity in responses to /ga/ at 540—630 ms) scored significantly lower in phonological skills, rapid naming, and letter knowledge than the control children (N = 10) without enhanced right hemispheric speech processing. These results further extend our earlier findings of newborn ERPs in predicting poorer language skills. These consistent differences in ERPs to speech sounds may have applications in the future for the early identification of children at risk for developmental language problems. This would facilitate well-directed intervention even before reading problems are typically diagnosed.

Individual differences in ERPs during mental rotation of characters: Lateralization, and performance level

The cognitive process of imaging an object turning around is called mental rotation. Many studies have been put forward analyzing mental rotation by means of event-related potentials (ERPs). Event-related potentials (ERPs) were measured during mental rotation of characters in a sample ( N = 82) with a sufficient size to obtain even small effects. A bilateral ERP amplitude modulation as a function of angular displacement was observed at parietal leads without any lateralization. Sex had no effect on mental rotation of characters, neither with respect to performance nor with respect to brain potentials. When the sample was split into groups of high- and low-performers, however, the results indicated (a) in line with the idea of neural efficiency substantially larger amplitudes for low-performers; (b) that the smaller amplitudes of the high-performers involved larger parietal networks; and (c) a left-parietal disengagement of neural activity for high-performers but a right-parietal disengagement for low-performers. The latter finding became evident through an analysis of internal consistencies of ERP amplitudes across conditions and performance levels, showing that internal consistencies were reduced at all three leads in the high-performance group for the biggest rotation angle, relative the other conditions and the low-performing group.

The relation between race-related implicit associations and scalp-recorded neural activity evoked by faces from different races

The neural correlates of the perception of faces from different races were investigated. White participants performed a gender identification task in which Asian, Black, and White faces were presented while event-related potentials (ERPs) were recorded. Participants also completed an implicit association task for Black (IAT-Black) and Asian (IAT-Asian) faces. ERPs evoked by Black and White faces differed, with Black faces evoking a larger positive ERP that peaked at 168 ms over the frontal scalp, and White faces evoking a larger negative ERP that peaked at 244 ms. These Black/White ERP differences significantly correlated with participants’ scores on the IAT-Black. ERPs also differentiated White from Asian faces and a significant correlation was obtained between the White-Asian ERP difference waves at ~500 ms and the IAT-Asian. A positive ERP at 116 ms over occipital scalp differentiated all three races, but was not correlated with either IAT. In addition, a late positive component (around 592 ms) was greater for the same race compared to either other race faces, suggesting potentially more extended or deeper processing of the same race faces. Taken together, the ERP/IAT correlations observed for both other races indicate the influence of a race-sensitive evaluative process that may include early more automatic and/or implicit processes and relatively later more controlled processes.

Human brain responsivity to different intensities of masked fearful eye whites: An ERP study

Previous studies have shown differential event-related potentials (ERPs) to intensities of fearful facial expressions. There are indications that the eyes may be particularly relevant for the recognition of fearful expressions, even the amount of white sclera exposed above and on sides of the dark pupil could activate the amygdala response. To investigate whether the ERP differences between intensities of fearful expressions are driven by the differential salience of the eyes in the fearful faces, ERPs were measured within a backward masking paradigm, where observers were asked to do a gender-decision task with male and female neutral faces. The emotional stimuli used were low-intensity (50%), prototypical (100%), and caricatured (150%) fearful eye whites that were derived from corresponding intensities of fearful faces respectively. Three groups of white squares that have the same pixels as the eye whites were created as control conditions. Analysis of the ERP data showed a linear increase in amplitudes of the parietal–occipital P120 by three intensities of fearful eye whites. These ERP effects were proved sensitive to intensities of negative emotions but not to the simple physical features as the same patterns of differences were not observed on white squares. Larger parietal–occipital P250 amplitudes were observed for caricatured 150% than low-intensity 50% fearful eye whites. It might reflect the subcortical pathway of emotion-specific, fearful processing. The results demonstrate that the human brain is sensitive to intensities of fear, even if just shown intensities of fearful eye white in the absence of awareness.

Neural correlates of affective picture processing — A depth ERP study

Using functional neuroimaging techniques (PET and fMRI), various cortical, limbic, and paralimbic structures have been identified in the last decade as neural substrates of human emotion. In this study we used a novel approach (intracerebral recordings of event-related potentials) to add to our knowledge of specific brain regions involved in affective picture processing. Ten intractable epileptic patients undergoing pre-surgical depth electrode recording viewed pleasant, neutral, and unpleasant pictures and intracerebral event-related potentials (ERPs) were recorded. A total of 752 cortical and subcortical sites were investigated. Significant differences in ERPs to unpleasant as compared to neutral or pleasant pictures were frequently and consistently observed in recordings from various brain areas – the mesial temporal cortex (the amygdala, the hippocampus, the temporal pole), the lateral temporal cortex, the mesial prefrontal cortex (ACC and the medial frontal gyrus), and the lateral prefrontal cortex. Interestingly, the mean latencies of responses to emotional stimuli were somewhat shorter in the frontal lobe structures (with evidently earlier activation within lateral prefrontal areas when compared to mesial prefrontal cortex) and longer in the temporal lobe regions. These differences, however, were not significant. Additional clearly positive findings were observed in some rarely investigated regions – in the posterior parietal cortex, the precuneus, and the insula. An approximately equivalent number of positive findings was revealed in the left and right hemisphere structures. These results are in agreement with a multisystem model of human emotion, distributed far beyond the typical limbic system and substantially comprising lateral aspects of both frontal lobes as well.

Priming and Backward Influences in the Human Brain: Processing Interactions during the Stroop Interference Effect

This study investigated neural processing interactions during Stroop interference by varying the temporal separation of relevant and irrelevant features of congruent, neutral, and incongruent colored-bar/color-word stimulus components. High-density event-related potentials (ERPs) and behavioral performance were measured as participants reported the bar color as quickly as possible, while ignoring the color words. The task-irrelevant color words could appear at 1 of 5 stimulus onset asynchronies (SOAs) relative to the task-relevant bar-color occurrence: -200 or -100 ms before, +100 or +200 ms after, or simultaneously. Incongruent relative to congruent presentations elicited slower reaction times and higher error rates (with neutral in between), and ERP difference waves containing both an early, negative-polarity, central-parietal deflection, and a later, more left-sided, positive-polarity component. These congruency-related differences interacted with SOA, showing the greatest behavioral and electrophysiological effects when irrelevant stimulus information preceded the task-relevant target and reduced effects when the irrelevant information followed the relevant target. We interpret these data as reflecting 2 separate processes: 1) a 'priming influence' that enhances the magnitude of conflict-related facilitation and conflict-related interference when a task-relevant target is preceded by an irrelevant distractor; and 2) a reduced 'backward influence' of stimulus conflict when the irrelevant distractor information follows the task-relevant target.

Dysfunctional response preparation and inhibition during a visual Go/Nogo task in children with two subtypes of attention-deficit hyperactivity disorder

While a response inhibition problem is well-established in children with attention-deficit/hyperactivity disorder of the combined subtype (AD/HDcom), the predominantly inattentive subtype (AD/HDin) has not been investigated previously. This study examined control versus subtype differences in visually evoked response inhibition using task performance and event-related potential (ERP) measures. Children with AD/HDcom ( n = 15) and AD/HDin ( n = 15) and age-matched controls ( n = 15) performed a cued visual Go/Nogo task requiring either activation or inhibition (30%) of a button-press response to the S2 (Go or Nogo stimulus) following the S1 (warning stimulus), presented 1380 ms earlier. Task performance and ERP indices of Warning, Go and Nogo stimulus processing, as well as preparation during the S1–S2 interval, were examined for group differences. Behavioural results indicated a response inhibition deficit in children with AD/HDcom and AD/HDin, with additional response activation problems in AD/HDcom. Topographic ERP differences between controls and both clinical groups suggested atypical (a) preparation for S2 as indexed by the late CNV, (b) early sensory/attentional processing of both S1 and S2, and (c) response inhibition as indexed by N2 and P3. In addition to replicating previous AD/HDcom findings, these results indicate that children with AD/HDin differ from controls in response preparation and inhibition during a cued visual Go/Nogo task.

A Polymorphism of the MAOA Gene is Associated with Emotional Brain Markers and Personality Traits on an Antisocial Index

Association studies suggest that the low activity variant of the monoamine oxidase A (MAOA)-uVNTR polymorphism confers risk for emotional disturbances associated with antisocial traits, particularly in males. Here, we assessed the low (MAOA-L) activity variant in relation to both brain function and a behavioral index of antisocial traits. From an initial sample of 290 healthy participants, 210 had low (MAOA-L) or high (MAOA-H) activity variants. Participants underwent a brief assessment of personality traits and event-related potential (ERP) recording during an emotion-processing task. Genotype differences in ERPs were localized using LORETA. The MAOA-L genotype was distinguished by elevated scores on the index of antisocial traits. These traits were related to altered ERPs elicited 120-280ms post-stimulus, particularly for negative emotion. Altered neural processing of anger in MAOA-L genotypes was localized to medial frontal, parietal, and superior temporo-occipital regions in males, but only to the superior occipital cortex in females. The MAOA low activity variant may increase susceptibility to antisocial traits through alterations to the neural systems for processing threat-related emotion, especially for males. Monoamines such as noradrenalin and serotonin may modulate these relationships, given that their metabolism varies according to MAOA variants, and that they modulate both emotional brain systems and antisocial aggression.