Event-related Potential Results Research Articles

Brain responses to case-marking violations in German preschool children

The processing of case-marking and argument structures was investigated in children at the age of 3 years, 4 years and 6 months, and 6 years. Two event-related potential (ERP) experiments were conducted in a case-marked language, i.e. German, comparing the processing of (a) double-nominative violations with subject-initial structures and (b) double-accusative violations with object-initial structures. It is known that for both violation types, adults display a biphasic N400/P600 ERP response, reflecting thematic-semantic, and syntactic processes. For double-nominative violations, 3-year-old children already show an adult-like processing pattern revealing their abilities to repair the tested structure. For double-accusative violations, ERP results indicate developmental processing differences with even 6-year-old children not showing an adult pattern. This suggests a late development of the complete function of the accusative case.

Age related effects on working memory: event-related potential differences between high and low performing old and young adults

Event Abstract Back to Event Age related effects on working memory: event-related potential differences between high and low performing old and young adults Emi Saliasi1*, Linda Geerligs2, Monicque M. Lorist2 and Natasha M. Maurits3 1 University Medical Center Groningen, Netherlands 2 Experimental Psychology, University of Groningen, Netherlands 3 Department of Neurology, University Medical Center Groningen, Netherlands Most studies on age-related changes in cognition focused on differences between groups of young and old adults and did not study variability within groups. However, some old adults show lower performance during cognitive tasks, others achieve performance comparable to young adults. To examine whether age-related effects on behavioral and event related potential (ERP) measures depend on performance level, we recorded an electroencephalogram from 37 young (18-26 years) and 36 old (60-74 years) healthy adults, during an n-back task with two loads (0- and 1-back) and two versions (identity and integrated). Participants were split in high and low performers. As expected, we found that high performing elderly (HPE) were faster and more accurate than low performing elderly (LPE). This variability in performance was reflected in higher P3 amplitude for high performing young, followed by low performing young, LPE and the lowest P3 amplitude for HPE. Moreover, brain activity in elderly was characterized by frontal hyperactivity and parietal hypoactivity, lasting from 100 ms until 900 ms post-stimulus. Other ERP differences related to task load and version, age and performance level, started at early visual encoding stages and persisted. We thus found that age related effects on ERP measures differed between high and low performers. The frontal hyperactivity and lower P3 amplitude might indicate that elderly perceive the task as more demanding and engage more effort to maintain performance. In HPE this indeed resulted in adequate performance levels. Although LPE also devoted effort to the task as reflected in the ERP results, this did not improve their performance. These results might suggest that the elderly differ in efficiency with which age related decline can be compensated. Keywords: Aging, ERP Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Cognitive Aging Citation: Saliasi E, Geerligs L, Lorist MM and Maurits NM (2011). Age related effects on working memory: event-related potential differences between high and low performing old and young adults. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00615 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: 15 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Emi Saliasi, University Medical Center Groningen, Groningen, Netherlands, e.saliasi@neuro.umcg.nl 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 Emi Saliasi Linda Geerligs Monicque M Lorist Natasha M Maurits Google Emi Saliasi Linda Geerligs Monicque M Lorist Natasha M Maurits Google Scholar Emi Saliasi Linda Geerligs Monicque M Lorist Natasha M Maurits PubMed Emi Saliasi Linda Geerligs Monicque M Lorist Natasha M Maurits 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.

The development of inhibitory control: An averaged and single-trial Lateralized Readiness Potential study

Inhibitory control (IC) is an important contributor to educational performance, and undergoes rapid development in childhood. Age-related changes in IC were assessed using an in-depth analysis of reaction time, the Lateralized Readiness Potential (LRP), and other event-related potential (ERP) measures to control for speed of processing. Five-year-olds, 8-year-olds and adults completed an adapted Stroop task. Both reaction time and ERP results suggest that IC does develop in this age range, over and above changes in speed of processing. The LRP identified two processes that contribute to IC. These processes develop at different rates--an early process, involving how the conflict is initially responded to is mature by age 5, while a later process, involving how the conflict is overcome is still developing after 8 years of age. We propose that these early and late processes reflect interference suppression and response inhibition, respectively. Further, a single-trial analysis of the LRP in the incongruent condition provides evidence that the LRP is consistent across trials and functionally similar in each age group. These results corroborate previous findings regarding the development of IC, and present a new and useful tool for assessing IC across development.

Learning of musical and linguistic structures: comparing event-related potentials and behavior

To learn a new language, it is necessary for the learner to succeed in segmenting the continuous stream of sounds into significant units. Previous behavioral studies have shown that it is possible to segment a language or musical stream based only on probabilities of occurrence between adjacent syllables/tones. Here we used a sung language and tested participants' learning of both linguistic and musical structures while recording electroencephalography. Although behavioral results showed learning of the linguistic structure only, event-related potential results for both dimensions showed a negative component sensitive to the degree of familiarity of items. We discuss this component as an index of lexical search, also pointing to the greater sensitivity of the event-related potentials compared to the behavioral responses.

Automatic Attention Orienting By Eye-gazed Cues In Children With Dcd: A Cognitive Psycho-physiological Study

The theories of the cognitive anatomy of attention may be a simple and clinically feasible method to gain insight into the mechanisms of the potential neuropathology underlying the coordination deficit in children with developmental coordination disorder (DCD). However, there have been no preceding studies comparing the inhibitory control and event-related potential results to an identical eye-gazed cues reaction task with bilateral lower extremities in children with DCD and typically developing children. PURPOSE: To investigate and compare the behavioral performance and event-related potentials (ERPs) measures in children with DCD and typically developing (TD) children when performing a visuospatial attention task with automatic (exogenous) orienting. METHODS: Twenty-four children with DCD and 24 TD children were recruited and presented with central eye-gazed cues directing them to attend covertly to the right or left field location, or straight away. All participants should detect and respond to laterally presented reaction signals via stepping pedals with their bilateral lower limbs when performing the task while recorded brain ERPs simultaneously. RESULTS: Behavioral data showed that children with DCD responded slowly (F 1,46 = 61.72, p < 0.001, partial h2 = 0.57) and exhibited a deficit in the disengage operation of directing covert operation as compared to TD children (F1,46 = 9.09, p = 0.004, partial h2 = 0.17). In terms of electrophysiological characteristics, children with DCD also showed distinct effects upon longer N2 (F1,46 = 9.05, p = 0.004, partial h2 = 0.16) and P3 latencies (F1,46 = 8.83, p = 0.005, partial h2 = 0.16), smaller P3 amplitude (F1,46 = 6.58, p = 0.014, partial h2 = 0.13), an elongated interval between N2 and the motor response (F1,46 = 42.53, p < 0.001, partial h2 = 0.48), and small areas on contingent negative variation (F1,46 = 8.55, p =.005, partial h2 = 0.16). CONCLUSIONS: Children with DCD showed a deficit in the automatic attention orienting, probably owing to slower response inhibitory process and stimulus classification speed, less ability in interhemispheric and cognitive-to-motor transfer speed, and less mature abilities on anticipatorily executive process and motor preparatory.

Broca 영역에서의 뇌파 변화에 기반한 뇌-컴퓨터 인터페이스

In this paper, we measured EEG signals on frontal and Broca`s area when subjects imagine to speak A or B or C or D. These signals were analyzed by Event-Related Spectral Perturbation (ERSP), Inter-Trial Coherence (ITC) and Event Related Potential (ERP) methods. As a result, high coherences were showed at 113Hz during 0300ms after the stimuli of each character and P300 was seen clearly and there are several differences between the ERP results. However, unlike the motivation of this study to classify the characters, it is impossible that we can classify each intention or each character cause these differences. Nevertheless, this paper suggest an application system using this results so BCI can provide various services.

Attention rivalry under irrelevant audiovisual stimulation

Audiovisual integration has been known to enhance perception; nevertheless, another fundamental audiovisual interaction, i.e. attention rivalry, has not been well investigated. This paper studied the attention rivalry under irrelevant audiovisual stimulation using event-related potential (ERP) and behavioral analysis, and tested the existence of a vision dominated rivalry model. Participants need respond to the target in a bi- or unimodal audiovisual stimulation paradigm. The enhanced amplitude of central P300 under visual target bimodal stimulus indicated that vision demanded more cognitive resources, and the significant amplitude of frontal P200 under bimodal stimulus with non-target auditory stimulus implied that the brain mostly restrained the process of the non-target auditory information. ERP results, together with the analysis of the behavioral data and the subtraction waves, indicated a vision dominated attention rivalry model involved in audiovisual interaction. Furthermore, the latencies of P200 and P300 components implied that audiovisual attention rivalry occurred within the first 300ms after stimulus onset, i.e. significant differences were found in P200 latencies among three target bimodal stimuli, while no difference existed in P300 latencies. Attention shifting and re-directing might be the cause of such early audiovisual rivalry.

The Neural Integration of Speaker and Message

When do listeners take into account who the speaker is? We asked people to listen to utterances whose content sometimes did not match inferences based on the identity of the speaker (e.g., "If only I looked like Britney Spears" in a male voice, or "I have a large tattoo on my back" spoken with an upper-class accent). Event-related brain responses revealed that the speaker's identity is taken into account as early as 200-300 msec after the beginning of a spoken word, and is processed by the same early interpretation mechanism that constructs sentence meaning based on just the words. This finding is difficult to reconcile with standard "Gricean" models of sentence interpretation in which comprehenders initially compute a local, context-independent meaning for the sentence ("semantics") before working out what it really means given the wider communicative context and the particular speaker ("pragmatics"). Because the observed brain response hinges on voice-based and usually stereotype-dependent inferences about the speaker, it also shows that listeners rapidly classify speakers on the basis of their voices and bring the associated social stereotypes to bear on what is being said. According to our event-related potential results, language comprehension takes very rapid account of the social context, and the construction of meaning based on language alone cannot be separated from the social aspects of language use. The linguistic brain relates the message to the speaker immediately.

Functional Plasticity in Ventral Temporal Cortex following Cognitive Rehabilitation of a Congenital Prosopagnosic

We used functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) to measure neural changes associated with training configural processing in congenital prosopagnosia, a condition in which face identification abilities are not properly developed in the absence of brain injury or visual problems. We designed a task that required discriminating faces by their spatial configuration and, after extensive training, prosopagnosic MZ significantly improved at face identification. Event-related potential results revealed that although the N170 was not selective for faces before training, its selectivity after training was normal. fMRI demonstrated increased functional connectivity between ventral occipital temporal face-selective regions (right occipital face area and right fusiform face area) that accompanied improvement in face recognition. Several other regions showed fMRI activity changes with training; the majority of these regions increased connectivity with face-selective regions. Together, the neural mechanisms associated with face recognition improvements involved strengthening early face-selective mechanisms and increased coordination between face-selective and nonselective regions, particularly in the right hemisphere.

Performance monitoring, error processing, and evaluative control following severe TBI

Patients with severe traumatic brain injury (TBI) often demonstrate impairments in performance monitoring--an evaluative control process that can be measured using the error-negativity/error-related negativity (Ne/ERN) and post-error positivity (Pe). The Ne/ERN and Pe are event-related potential (ERP) components generated following errors, with current theories suggesting the Ne/ERN reflects automatic performance monitoring and the Pe reflects error processing and awareness. To elucidate the electrophysiological mechanisms of performance monitoring deficits following severe TBI, behavioral and ERP measurements were obtained, whereas participants with severe TBI and neurologically-healthy comparison participants performed a modified color-naming version of the Stroop task. Behaviorally, both groups demonstrated robust response-time (RT) and error-rate interference. Participants with TBI exhibited generalized RT slowing; no significant between-groups interactions were present for RTs or error rates. ERP results indicate Ne/ERN amplitude was attenuated in participants with TBI, whereas the pattern of Pe amplitude did not clearly differentiate groups. Findings suggest the Ne/ERN as a potential electrophysiological marker of evaluative control/performance monitoring impairment following TBI. Implications for future research and potential clinical application as well as potential limitations in conducting electrophysiological research in neurologically-impaired populations are discussed.

The temporal dynamics of selective attention of the visual periphery as measured by classification images

This study estimates the temporal dynamics of selective attention with classification images, a technique assessing observer information use by tracking how responses are correlated with external noise added to the stimulus. Three observers performed a yes/no discrimination of a Gaussian signal that could appear at one of eight locations (eccentricity-4.6 degrees ). During the stimulus duration (300 ms), a peripheral cue indicated the potential signal location with 100% validity, and stimuli were presented in frames (37.5 ms/frame) of independently sampled Gaussian luminance image noise. Stimuli were presented either with or without a succeeding masking display (100 ms) of high-contrast image noise, with mask presence having little effect. The results from the classification images suggest that observers were able to use information at the cued location selectively (relative to the uncued locations), starting within the first (0-37.5 ms) or second (37.5-75 ms) frame. This suggests a selective attention effect earlier than those found in previous behavioral and event-related potential (ERP) studies, which generally have estimated the latency for selective attention effects to be 75-100 ms. We present a deconvolution method using the known temporal impulse response of early vision that indicates how the classification image results might relate to previous behavioral and ERP results. Applying the model to the classification images suggests that accounting for the known temporal dynamics could explain at least part of the difference in results between classification images and the previous studies.

The self in conflict: The role of executive processes during truthful and deceptive responses about attitudes

This study sought to extend previous results regarding deceptions about specific memories by investigating the role of executive processes in deceptions about evaluative judgments. In addition, given that previous studies of deception have not included valence manipulations, we also wanted to determine whether the goodness/badness aspect of the items would affect the processes used during deception. Thus, we compared behavioral and event-related potential (ERP) activity while participants made truthful and directed lie (i.e., press opposite of the truth) responses about attitude items with which they either strongly agreed or disagreed. Consistent with previous results, deceptive responses required greater cognitive control as indicated by slower RTs, larger medial frontal negativities (MFN) and smaller late positive components than truthful responses. Furthermore, the magnitude of these deception-related effects was dependent on the valence that participants assigned to the items (i.e., agree/disagree). Directed lie responses about attitudes also resulted in greatly reduced pre-response positivities, an indication that participants strategically monitored their responses even in the absence of explicit task demands. Item valence also differentially affected the amplitude of three ERP components in a 650 ms pre-response interval, independently of whether truthful or deceptive responses were made. Analyses using dipole locations based on results from fMRI studies of evaluative judgments and deception indicated a high degree of overlap between the ERP and fMRI results and revealed the possible temporal characteristics of the hemodynamic activations.

Self-face recognition in attended and unattended conditions: an event-related brain potential study

This study investigated whether neural mechanisms of self-face recognition are modulated by attention by recording event-related brain potentials associated with self-face recognition. Participants identified head orientations of self-faces and familiar or unfamiliar other faces presented briefly at the center of the visual field. Event-related brain potentials to self-faces and other faces were recorded when self-faces and familiar or unfamiliar other faces were either task relevant (attended) or irrelevant (unattended) in separate blocks of trials. We found that early face-specific event-related brain potential components such as the N170 and vertex positive potential did not differ between self-faces and other faces. Relative to familiar faces, however, self-faces induced an increased positivity over the frontocentral area at 220-700 ms. The increased positivity to self-faces relative to familiar faces between 500 and 700 ms was reduced in the attended relative to the unattended conditions, which arose from the fact that the amplitude to familiar faces during this time window was increased in the attended relative to the unattended conditions, whereas the event-related brain potential amplitude to self-faces was not influenced by attention. The event-related brain potential results suggest an automatic process of self-face recognition in human brains that occurs after face structure encoding and is independent of task relevance.

Cognitive inhibition of number/length interference in a Piaget-like task in young adults: evidence from ERPs and fMRI.

We sought to determine whether the neural traces of a previous cognitive developmental stage could be evidenced in young adults. In order to do so, 12 young adults underwent two functional imaging acquisitions (EEG then fMRI). During each session, two experimental conditions were applied: a Piaget-like task with number/length interference (INT), and a reference task with number/length covariation (COV). To succeed at Piaget's numerical task, which children under the age of 7 years usually fail, the subjects had to inhibit a misleading strategy, namely, the visuospatial length-equals-number bias, a quantification heuristic that is often relevant and that continues to be used through adulthood. Behavioral data confirmed that although there was an automation in the young adult subjects as assessed by the very high number of accurate responses (>97%), the inhibition of the "length equals number strategy" had a cognitive cost, as the reaction times were significantly higher in INT than in COV (with a difference of 230 ms). The event-related potential results acquired during the first session showed electrophysiological markers of the cognitive inhibition of the number/length interference. Indeed, the frontal N2 was greater during INT than during COV, and a P3(late)/P6 was detected only during INT. During the fMRI session, a greater activation of unimodal areas (the right middle and superior occipital cortex) and in the ventral route (the left inferior temporal cortex) was observed in INT than in COV. These results seem to indicate that when fully automated in adults, inhibition processes might take place in unimodal areas.

Attending to visual or auditory motion affects perception within and across modalities: An event-related potential study

The present event-related potential (ERP) study examined the role of dynamic features in multisensory binding. It was tested whether endogenous attention to the direction of motion affects processing of visual and auditory stimuli within and across modalities. Human participants perceived horizontally moving dot patterns and sounds that were presented either continuously (standards) or briefly interrupted (infrequent deviants). Their task was to detect deviants moving in a particular direction within a primary modality, but to detect all deviants irrespective of their motion direction within the secondary modality. Attending to the direction of visual motion resulted in a broad selection negativity (SN) starting at about 200 ms post-stimulus onset, and attending to the direction of auditory motion resulted in a positive difference wave at 150 ms that was followed by a broad negativity starting at about 200 ms (unimodal effects). Moreover, dot patterns moving in a direction that was attended within audition were detected faster and more accurately than oppositely moving stimuli and elicited a cross-modal SN wave. Corresponding cross-modal behavioural and ERP results were obtained for sounds moving in a direction that was attended within vision. Unimodal and cross-modal ERP attention effects partially differed in their scalp topography. The present study shows that dynamic features (direction of motion) may be used to link input across modalities and demonstrates for the first time that these multisensory interactions take place as early as about 200 ms after stimulus onset.

Neural mechanisms of attentional modulation of perceptual grouping by collinearity

Psychophysical research showed that detection of an oriented visual target is facilitated when the target is grouped with collinear visual flankers. However, this collinear grouping effect is evident only when the flankers are attended. This study examined neural mechanisms underlying the interaction between attention and grouping by collinearity. Event-related potentials were recorded from study participants who judged whether oriented Gabor patches (i.e. visual elements consisting of a sinusoidal contrast modulation convolved with a Gaussian function) along the cued orientation were collinear or orthogonal. Event-related potentials showed an enhanced negativity over the posterior occipital cortex at 48-72 ms when collinear patches were congruent rather than incongruent with the cued orientation. A negative shift between 260 and 380 ms was observed over the occipital-parietal areas in the congruent rather than incongruent conditions. The long-latency effect, however, was evident only when the collinear patches were allocated along 45 degrees . The event-related potential results suggest that the interaction between attention and collinear grouping may take place as early as in the primary visual cortex and is independent of global orientations of perceptual groups.

Dynamics of task sets: Evidence from dense-array event-related potentials

Prior research suggests that task sets facilitate coherent, goal-directed behavior by providing an internal, contextual frame that biases selection toward context-relevant stimulus attributes and responses. Questions about how task sets are engaged, maintained, and shifted have recently become a major focus of research on executive control processes. We employed dense-array (128-channel) event-related potential (ERP) methodology to examine the dynamics of brain systems engaged during the preparation and implementation of task switching. The EEG was recorded while participants performed letter and digit judgments to pseudorandomly-ordered, univalent (#3, A%) and bivalent (G5) stimulus trials, with the appropriate task cued by a colored rectangle presented 450 ms before target onset. Results revealed spatial and temporal variations in brain activity that could be related to preparatory processes common to both switch and repeat trials, switch-specific control processes engaged to reconfigure and maintain task set under conflict, and visual priming benefits of task repetition. Despite extensive practice and improvement, both behavioral and ERP results indicated that subjects maintained high levels of executive control processing with extended task engagement. The patterns of ERP activity obtained in the present study fit well with functional neuroanatomical models of self-regulation of action. The frontopolar and right-lateralized frontal switch effects obtained in the present study are consistent with the role of these regions in adapting to changing contextual contingencies. In contrast, the centroparietal P3b and N384 effects related to the contextual ambiguity of bivalent trials are consistent with the context monitoring and updating functions associated with the posterior cingulate learning circuit.

Attending to visual or auditory motion affects perception within and across modalities: an event‐related potential study

The present event-related potential (ERP) study examined the role of dynamic features in multisensory binding. It was tested whether endogenous attention to the direction of motion affects processing of visual and auditory stimuli within and across modalities. Human participants perceived horizontally moving dot patterns and sounds that were presented either continuously (standards) or briefly interrupted (infrequent deviants). Their task was to detect deviants moving in a particular direction within a primary modality, but to detect all deviants irrespective of their motion direction within the secondary modality. Attending to the direction of visual motion resulted in a broad selection negativity (SN) starting at about 200 ms post-stimulus onset, and attending to the direction of auditory motion resulted in a positive difference wave at 150 ms that was followed by a broad negativity starting at about 200 ms (unimodal effects). Moreover, dot patterns moving in a direction that was attended within audition were detected faster and more accurately than oppositely moving stimuli and elicited a cross-modal SN wave. Corresponding cross-modal behavioural and ERP results were obtained for sounds moving in a direction that was attended within vision. Unimodal and cross-modal ERP attention effects partially differed in their scalp topography. The present study shows that dynamic features (direction of motion) may be used to link input across modalities and demonstrates for the first time that these multisensory interactions take place as early as about 200 ms after stimulus onset.

Differential Contribution of Frontal and Temporal Cortices to Auditory Change Detection: fMRI and ERP Results

The present study addresses the functional role of the temporal and frontal lobes in auditory change detection. Prior event-related potential (ERP) research suggested that the mismatch negativity (MMN) reflects the involvement of a temporofrontal network subserving auditory change detection processes and the initiation of an involuntary attention switch. In the present study participants were presented with repetitive spectrally rich sounds. Infrequent changes of either small (10% change), medium (30% change), or large (100% change) magnitude were embedded in the stimulus train. ERPs and fMRI measures were obtained in the same subjects in subsequent sessions. Significant hemodynamic activation in the superior temporal gyri (STG) bilaterally and the opercular part of the right inferior frontal gyrus was observed for large and medium deviants only. ERPs showed that small deviants elicited MMN when presented in silence but not when presented with recorded MR background noise, indicating that small deviants were hardly detected under fMRI conditions. The MR signal change in temporal lobe regions was larger for large than for medium deviants. For the right fronto-opercular cortex the opposite pattern was observed. The strength of the temporal activation correlated with the amplitude of the change-related ERP at around 110 ms from stimulus onset while the frontal activation correlated with the change-related ERP at around 150 ms. These results suggest that the right fronto-opercular cortex is part of the neural network generating the MMN. Three alternative explanations of these findings are discussed.

The effect of immediate and delayed word repetition on event-related potential in a continuous recognition task

The dissociation of immediate and delayed word repetition was studied using a continuous recognition memory task and event-related potential (ERP). Among 240 stimulus words, 40 words were not repeated, 100 were immediately repeated and 100 were repeated after 5 intervening words. Words presented only once during the experiment were referred to as new words. Subjects responded faster and more accurately to words repeated immediately than to new words and to words repeated after a delay. In terms of ERP results, immediate repetition was associated with large P300 amplitude, early P300 latency and the absence of N400, while delayed repetition was associated with small P300 amplitude, late P300 latency and the presence of N400. N400 was elicited only to new words and to those repeated after intervening words. The general morphology of the waveforms was similar for two repetition conditions until around 310 ms after the onset of stimulus. These results indicate that distinct neural systems subserve the immediate and delayed repetition effect, and that the difference between the two emerges around 310 ms poststimulus. Immediate and delayed word repetition are considered in terms of template matching and memory searching, and are possibly mediated by the parietal and left medial temporal lobes, respectively.