Event-related Brain Potentials Effects Research Articles

Exceptions and anomalies: An ERP study on context sensitivity in autism

Several studies have demonstrated that people with ASD and intact language skills still have problems processing linguistic information in context. Given this evidence for reduced sensitivity to linguistic context, the question arises how contextual information is actually processed by people with ASD. In this study, we used event-related brain potentials (ERPs) to examine context sensitivity in high-functioning adults with autistic disorder (HFA) and Asperger syndrome at two levels: at the level of sentence processing and at the level of solving reasoning problems. We found that sentence context as well as reasoning context had an immediate ERP effect in adults with Asperger syndrome, as in matched controls. Both groups showed a typical N400 effect and a late positive component for the sentence conditions, and a sustained negativity for the reasoning conditions. In contrast, the HFA group demonstrated neither an N400 effect nor a sustained negativity. However, the HFA group showed a late positive component which was larger for semantically anomalous sentences than congruent sentences. Because sentence context had a modulating effect in a later phase, semantic integration is perhaps less automatic in HFA, and presumably more elaborate processes are needed to arrive at a sentence interpretation.

How personal earthquake experience impacts on the Stroop interference effect: An event-related potential study

Event-related brain potentials (ERPs) were measured when 24 Chinese subjects performed the classical Stroop task. All of subjects had experienced the great Sichuan earthquake (5/12), with 12 people in each of the Far (Chengdu city) and the Close (Deyang city) earthquake experience groups. The behavioral data showed that the Stroop task yielded a robust Stroop interference effect as indexed by longer RT for incongruent than congruent color words in both the Chengdu and Deyang groups. Scalp ERP data showed that incongruent stimuli elicited a more negative ERP deflection (N400-600; Stroop interference effect) than did congruent stimuli between 400-600 ms in the Chengdu group, while the Stroop interference ERP effect was not found in the Deyang group. Dipole source analysis localized the generator of the N400-600 in the right prefrontal cortex (PFC) and was possibly related to conflict monitoring and cognitive control.

Stimulus and response conflict in the color–word Stroop task: A combined electro-myography and event-related potential study

We aimed to separate stimulus and response conflict in a manual color–word Stroop task by combining electro-myography (EMG) and event-related brain potentials (ERPs). EMG served as a measure of response conflict by detecting incorrect response hand activation in correctly responded trials. Response conflict was enhanced in both the incongruent and congruent conditions relative to neutral conditions. This suggests that the Stroop conflict (incongruent vs. congruent condition) could be explained by stimulus conflict in our study and that response conflict was not restricted to the incongruent condition of the Stroop task. Incorrect response activity was detected in a neutral condition using words but not in a neutral condition with non-words. This suggests that the mere presence of task-irrelevant stimuli semantically related to task-relevant stimuli can prime incorrect response activity. The above factors are important to consider in studies which do not have any explicit measure of response conflict. We have detected a robust marker of Stroop conflict, the N450 ERP effect, which has been related to ACC activity. The N450 was probably affected by stimulus conflict in our study and it may be a marker of general conflict processing.

Re-evaluating the Time Course of Gender and Phonological Encoding During Silent Monitoring Tasks Estimated by ERP: Serial or Parallel Processing?

Neurolinguistic and psycholinguistic studies suggest that grammatical (gender) and phonological information are retrieved independently and that gender can be accessed before phonological information. This study investigated the relative time courses of gender and phonological encoding using topographic evoked potentials mapping methods. Event-related brain potentials (ERPs) were recorded using a high resolution electroencephalogram (EEG) system (128 channels) during gender and phoneme monitoring in silent picture naming. Behavioural results showed similar reaction times (RT) between gender and word onset (first phoneme) monitoring, and longer RT when monitoring the second syllable onset. Temporal segmentation analysis (defining dominant map topographies using cluster analysis) revealed no timing difference between gender monitoring and word onset monitoring: both effects fall within the same time window at about 270-290 ms after picture presentation. Monitoring a second syllable onset generated a later effect at about 480 ms. Direct comparison between gender and first phoneme monitoring revealed a difference of only 10 ms between tasks at approximately 200 ms. Taken together, these results suggest that lemma retrieval and phonological encoding may proceed in parallel or overlap. Word onset is retrieved simultaneously with gender, while the longer RT and the later ERP effect for second syllable onset reflect that segmental encoding continues incrementally to the following phonemes.

Cortical Information Processing in Coma

To evaluate cortical information processing (particularly, semantic processing) in acute nontraumatic coma by means of event-related brain potentials (ERPs). The tests included measures of obligatory auditory processing (N100), automatic (Mismatch Negativity) and controlled (P300) detection of stimulus deviance, and semantic processing (ERP effects in word pairs and sentences). The tests were presented to 20 healthy participants and 42 coma patients with Glasgow Coma Scale <9. Responders (ie, patients whose ERP data indicate that their brain was able to process the corresponding stimuli) were found in each ERP test, and their distribution was statistically different from that expected by chance. Particularly, 7 responders were found in the word pair paradigm and 3 responders in the sentence paradigm. The P300 responsiveness highly correlated with other ERP responses, with Glasgow Coma Scale and with the future development of coma (ie, P300 on day 4 was related to the clinical state on day 20). Results suggest a wide range of cortical information processing in coma, including semantic processing. The question is discussed of whether, and to what extent, these processing operations are related to conscious awareness of stimuli.

Time course and task dependence of emotion effects in word processing

The emotional content of stimuli influences cognitive performance. In two experiments, we investigated the time course and mechanisms of emotional influences on visual word processing in various tasks by recording event-related brain potentials (ERPs). The stimuli were verbs of positive, negative, and neutral valence. In Experiment 1, where lexical decisions had to be performed on single verbs, both positive and negative verbs were processed more quickly than neutral verbs and elicited a distinct ERP component, starting around 370 msec. In Experiment 2, the verbs were embedded in a semantic context provided by single nouns. Likewise, structural, lexical, and semantic decisions for positive verbs were accelerated, and an ERP effect with a scalp distribution comparable to that in Experiment 1 now started about 200 msec earlier. These effects may signal an automatic allocation of attentional resources to emotionally arousing words, since they were not modulated by different task demands. In contrast, a later ERP effect of emotion was restricted to lexical and semantic decisions and, thus, appears to indicate more elaborated, task-dependent processing of emotional words.

Effects of intermodal attention on the auditory steady‐state response and the event‐related potential

The aim of the present study was to simultaneously measure and compare intermodal attention effects in event-related brain potentials (ERPs) and auditory steady-state responses (ASSRs). For this purpose, 40-Hz amplitude modulated tones and a visual fixation cross were presented concurrently. By means of target detection tasks either on the sounds or on the fixation cross, participants' attention was directed to the respective modality. Attended sounds elicited a negative difference (Nd) in the ERP relative to unattended sounds. Nd was divided into an early and a late part as often observed for intramodal attention. Moreover, attention to the sounds led to a significant enhancement of the ASSR. This modulation of the ASSR by intermodal attention is demonstrated for the first time in the EEG. The present data suggest that ASSRs could provide a useful tool for the investigation of the neural dynamics of intermodal attentional processes.

Neural correlates of cued recall in young and older adults: an event-related potential study

This experiment investigated age differences in electrophysiological correlates of retrieval success in a word-stem cued recall task. Young adults (M+/-SD: 21.4 years+/-1.9) performed this memory task more accurately than older participants (M+/-SD: 65.1 years+/-3.3). Robust event-related brain potential (ERP) old/new effects were identified in both age groups. The main age differences were observed in latency and lateralization of ERP effects. Young adults exhibited a parietal effect that became focused over left parietal electrodes, whereas no asymmetry was observed in older adults. Moreover, ERP effects were more delayed in the older group. Overall, these findings provide some evidence of the reduction of processing speed during aging and suggest that young and older adults may recruit distinct cerebral patterns during episodic cued recall.

It all sounds the same to me: Sequential ERP and behavioral effects during pitch and harmonicity judgments

The representation of complex sounds was examined by comparing both behavioral and event-related brain potentials (ERPs) to the change or repetition of fundamental frequency (f0) and harmonicity. In the pitch task, participants were asked to categorize the incoming stimulus as either low or high, regardless of harmonicity, and in the harmonicity task, participants indicated whether the stimulus was tuned or mistuned, regardless of pitch. Over three experiments, participants were faster in responding to pitch than to harmonicity. As a result of this asymmetry, behavioral and ERP data showed that irrelevant changes in harmonicity had little impact on performance during the pitch task, whereas harmonicity judgments were impeded by irrelevant changes in f0. These data are consistent with both general horse-race accounts of processing and specific accounts of mistuning detection that posit prior f0 registration. In addition, ERP components N2 and P3 were modulated by both intertrial contingency and task instructions, revealing the further influence of top-down mechanisms on concurrent sound segregation.

Speeding Up Syntax: On the Relative Timing and Automaticity of Local Phrase Structure and Morphosyntactic Processing as Reflected in Event-related Brain Potentials

Neurolinguistic research utilizing event-related brain potentials (ERPs) typically relates syntactic phrase structure processing to an early automatic processing stage around 150 to 200 msec, whereas morphosyntactic processing is associated with a later and somewhat more attention-dependent processing stage between 300 and 500 msec. However, recent studies have challenged this position by reporting highly automatic ERP effects for morphosyntax in the 100 to 200 msec time range. The present study aimed at determining the factors that could contribute to such shifts in latency and automaticity. In two experiments varying the degree of attention, German phrase structure and morphosyntactic violations were compared in conditions in which the locality of the violated syntactic relation, as well as the violation point and the acoustic properties of the speech stimuli, were strictly controlled for. A negativity between 100 and 300 msec after the violation point occurred in response to both types of syntactic violations and independently of the allocation of attentional resources. These findings suggest that the timing and automaticity of ERP effects reflecting specific syntactic subprocesses are influenced to a larger degree by methodological than by linguistic factors, and thus, need to be regarded as relative rather than fixed to temporally successive processing stages.

The appraisal of facial beauty is rapid but not mandatory

Facial attractiveness is an important source of social affective information. Here, we studied the time course and task dependence of evaluating attractive faces from a viewer's perspective. Event-related brain potentials (ERPs) were recorded while participants classified color portraits of unfamiliar persons according to gender and facial attractiveness. During attractiveness classification, enhanced ERP amplitudes for attractive and nonattractive faces relative to faces of intermediate attractiveness were found for an early component around 150 msec and for the late positive complex (LPC). Whereas LPC enhancement conforms to previous studies employing various types of affective stimuli, the finding of an early effect extends earlier research on rapid emotion processing to the dimension of facial attractiveness. Dipole source localization of this early ERP effect revealed a scalp distribution suggesting activation of posterior extrastriate areas. Importantly, attractiveness-related modulations of brain responses were only marginal during the gender decision task, arguing against the automaticity of attractiveness appraisal.

Perceptual and motor conflict in the Stroop effect: Event-related brain potential and electromyography studies

Event Abstract Back to Event Perceptual and motor conflict in the Stroop effect: Event-related brain potential and electromyography studies Denes Szűcs1, 2*, F. Soltész1 and S. White1 1 University of Cambridge, United Kingdom 2 Hungarian Academy of Sciences, Hungary In a series of event-related brain potential (ERP) and electromyography (EMG) studies [Szűcs et al., 2007, Behav Brain Funct; Szűcs & Soltész, 2007 Neuropsychologia; Szűcs & Soltész, 2008, Brain Res; Szűcs, Soltész & White, submitted] we investigated the role of perceptual and motor conflict in the Stroop effect. We used the numerical Stroop paradigm where participants had to judge which of the two simultaneously presented numbers was larger physically or numerically. The physical-size comparison task is analogous to the classical color-word Stroop paradigm in that the irrelevant numerical meaning of numbers affects physical magnitude judgments. The lateralized readiness potential (LRP) was used to guide the separation of perceptual and motor conflict. In the first three studies, there were two major findings. First, between 150-250 ms we found early ERP markers of perceptual conflict. Second, at around 400 ms, after the onset of the LRP, we found late conflict-related ERP amplitude effects. We hypothesized that these late effects may be related to resolving motor response competition, or to slow, context-related stimulus-conflict detection. In a fourth study we used EMG electrodes placed on response hands to directly investigate the presence of motor conflict at the level of effectors in the Stroop paradigm. Incorrect response activation detected by EMG was temporally contingent with late ERP effects identified by our previous studies. Hence, we conclude that late ERP effects in the Stroop paradigm are at least partially related to motor response competition. Altogether our studies establish reliable ERP markers of perceptual and motor conflict in the Stroop effect. Conference: 10th International Conference on Cognitive Neuroscience, Bodrum, Turkey, 1 Sep - 5 Sep, 2008. Presentation Type: Poster Presentation Topic: Decision Making and Response Selection Citation: Szűcs D, Soltész F and White S (2008). Perceptual and motor conflict in the Stroop effect: Event-related brain potential and electromyography studies. Conference Abstract: 10th International Conference on Cognitive Neuroscience. doi: 10.3389/conf.neuro.09.2009.01.211 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: 08 Dec 2008; Published Online: 08 Dec 2008. * Correspondence: Denes Szűcs, University of Cambridge, Cambridge, United Kingdom, ds377@cam.ac.uk 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 Denes Szűcs F. Soltész S. White Google Denes Szűcs F. Soltész S. White Google Scholar Denes Szűcs F. Soltész S. White PubMed Denes Szűcs F. Soltész S. White 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 fractionation of spoken language understanding by measuring electrical and magnetic brain signals.

This paper focuses on what electrical and magnetic recordings of human brain activity reveal about spoken language understanding. Based on the high temporal resolution of these recordings, a fine-grained temporal profile of different aspects of spoken language comprehension can be obtained. Crucial aspects of speech comprehension are lexical access, selection and semantic integration. Results show that for words spoken in context, there is no 'magic moment' when lexical selection ends and semantic integration begins. Irrespective of whether words have early or late recognition points, semantic integration processing is initiated before words can be identified on the basis of the acoustic information alone. Moreover, for one particular event-related brain potential (ERP) component (the N400), equivalent impact of sentence- and discourse-semantic contexts is observed. This indicates that in comprehension, a spoken word is immediately evaluated relative to the widest interpretive domain available. In addition, this happens very quickly. Findings are discussed that show that often an unfolding word can be mapped onto discourse-level representations well before the end of the word. Overall, the time course of the ERP effects is compatible with the view that the different information types (lexical, syntactic, phonological, pragmatic) are processed in parallel and influence the interpretation process incrementally, that is as soon as the relevant pieces of information are available. This is referred to as the immediacy principle.

The effects of cortisol administration on approach–avoidance behavior: An event-related potential study

We investigated the effects of cortisol administration (50mg) on approach and avoidance tendencies in low and high trait avoidant healthy young men. Event-related brain potentials (ERPs) were measured during a reaction time task, in which participants evaluated the emotional expression of photographs of happy and angry faces by making an approaching (flexion) or avoiding (extension) arm movement. The task consisted of an affect-congruent (approach happy faces and avoid angry faces) and an affect-incongruent (reversed instruction) condition. Behavioral and ERP analyses showed that cortisol enhanced congruency effects for angry faces in highly avoidant individuals only. The ERP effects involved an increase of both early (P150) and late (P3) positive amplitudes, indicative of increased processing of the angry faces in high avoidant subjects after cortisol administration. Together, these results suggest a context-specific effect of cortisol on processing of, and adaptive responses to, motivationally significant threat stimuli, particularly in participants highly sensitive to threat signals.

Neurophysiological Evidence for the Time Course of Activation of Global Shape, Part, and Local Contour Representations during Visual Object Categorization and Memory

Categorization of visual objects entails matching a percept to long-term representations of structural knowledge. This object model selection is central to theories of human visual cognition, but the representational format(s) is largely unknown. To characterize these neural representations, event-related brain potentials (ERPs) to fragmented objects during an indirect memory test were compared when only local contour features, but not global shapes of the object and its parts, differed between encoding and retrieval experiences. The ERP effects revealed that the format of object representations varies across time according to the particular neural processing and memory system currently engaged. An occipito-temporal P2(00) showed implicit memory modulation to items that repeatedly engaged similar perceptual grouping processes but not items that merely reinstantiated visual features. After 500 msec, memory modulation of a late positive complex, indexing secondary categorization and/or explicit recollection processes, was sensitive to local contour changes. In between, a frontocentral N350, indexing the model selection and an implicit perceptual memory system, showed reactivation of object representations whenever the same global shapes were reactivated, despite local feature differences. These and prior N350 findings provide direct neurophysiological evidence that the neural representations supporting object categorization include knowledge beyond local contours and about higher-order perceptual structures, such as the global shapes of the object and its parts, that can differ between object views. The N350 is proposed to index a second state of interactive, recurrent, and feedback processing in occipital and ventral temporal neocortex supporting higher-order cognitive abilities and phenomenological awareness with objects.

Untangling syntactic and sensory processing: An ERP study of music perception

The present study investigated music-syntactic processing with chord sequences that ended on either regular or irregular chord functions. Sequences were composed such that perceived differences in the cognitive processing between syntactically regular and irregular chords could not be due to the sensory processing of acoustic factors like pitch repetition, pitch commonality (the major component of "sensory dissonance"), or roughness. Three experiments with independent groups of subjects were conducted: a behavioral experiment and two experiments using electroencephalography. Irregular chords elicited an early right anterior negativity (ERAN) in the event-related brain potentials (ERPs) under both task-relevant and task-irrelevant conditions. Behaviorally, participants detected around 75% of the irregular chords, indicating that these chords were only moderately salient. Nevertheless, the irregular chords reliably elicited clear ERP effects. Amateur musicians were slightly more sensitive to musical irregularities than nonmusicians, supporting previous studies demonstrating effects of musical training on music-syntactic processing. The findings indicate that the ERAN is an index of music-syntactic processing and that the ERAN can be elicited even when irregular chords are not detectable based on acoustical factors such as pitch repetition, sensory dissonance, or roughness.

Who are You Talking About? Tracking Discourse-level Referential Processing with Event-related Brain Potentials

In this event-related brain potentials (ERPs) study, we explored the possibility to selectively track referential ambiguity during spoken discourse comprehension. Earlier ERP research has shown that referentially ambiguous nouns (e.g., "the girl" in a two-girl context) elicit a frontal, sustained negative shift relative to unambiguous control words. In the current study, we examined whether this ERP effect reflects "deep" situation model ambiguity or "superficial" textbase ambiguity. We contrasted these different interpretations by investigating whether a discourse-level semantic manipulation that prevents referential ambiguity also averts the elicitation of a referentially induced ERP effect. We compared ERPs elicited by nouns that were referentially nonambiguous but were associated with two discourse entities (e.g., "the girl" with two girls introduced in the context, but one of which has died or left the scene), with referentially ambiguous and nonambiguous control words. Although temporally referentially ambiguous nouns elicited a frontal negative shift compared to control words, the "double bound" but referentially nonambiguous nouns did not. These results suggest that it is possible to selectively track referential ambiguity with ERPs at the level that is most relevant to discourse comprehension, the situation model.

Altered tactile spatial attention in the early blind

To investigate whether superior tactile acuity in the blind is due to alterations of attentional selection mechanisms, event-related brain potentials (ERPs) were measured in a group of early blind and a group of sighted individuals who performed a difficult tactile spatial selection task. We found systematic differences in the attentional processing of tactile events between early blind and sighted individuals. The blind not only responded faster to tactile targets, but also showed attentional modulations of early somatosensory ERP components (P100 and N140). In contrast, ERP effects of spatial attention in the sighted only emerged at longer-latencies (about 200 ms post-stimulus). Our findings suggest that increased use of one sense due to sensory deprivation, such as touch in blind people, leads to alterations of attentional selection mechanism within modality-specific cortex.

The t-CWT: A new ERP detection and quantification method based on the continuous wavelet transform and Student’s t-statistics

Objective This study was aimed at developing a method for extraction and assessment of event-related brain potentials (ERP) from single-trials. This method should be applicable in the assessment of single persons’ ERPs and should be able to handle both single ERP components and whole waveforms. Methods We adopted a recently developed ERP feature extraction method, the t-CWT, for the purposes of hypothesis testing in the statistical assessment of ERPs. The t-CWT is based on the continuous wavelet transform (CWT) and Student’s t-statistics. The method was tested in two ERP paradigms, oddball and semantic priming, by assessing individual-participant data on a single-trial basis, and testing the significance of selected ERP components, P300 and N400, as well as of whole ERP waveforms. The t-CWT was also compared to other univariate and multivariate ERP assessment methods: peak picking, area computation, discrete wavelet transform (DWT) and principal component analysis (PCA). Results The t-CWT produced better results than all of the other assessment methods it was compared with. Conclusions The t-CWT can be used as a reliable and powerful method for ERP-component detection and testing of statistical hypotheses concerning both single ERP components and whole waveforms extracted from either single persons’ or group data. Significance The t-CWT is the first such method based explicitly on the criteria of maximal statistical difference between two average ERPs in the time–frequency domain and is particularly suitable for ERP assessment of individual data (e.g. in clinical settings), but also for the investigation of small and/or novel ERP effects from group data.

Processing focus structure and implicit prosody during reading: Differential ERP effects

Several recent studies have shown that focus structural representations influence syntactic processing during reading, while other studies have shown that implicit prosody plays an important role in the understanding of written language. Up until now, the relationship between these two processes has been mostly disregarded. The present study disentangles the roles of focus structure and accent placement in reading by reporting event-related brain potential (ERP) data on the processing of contrastive ellipses. The results reveal a positive-going waveform (350–1300 ms) that correlates with focus structural processing and a negativity (450–650 ms) interpreted as the correlate of implicit prosodic processing. The results suggest that the assignment of focus as well as accent placement are obligatory processes during reading.