Event-related Potential Effects Research Articles

Language ERPs reflect learning through prediction error propagation

Event-related potentials (ERPs) provide a window into how the brain is processing language. Here, we propose a theory that argues that ERPs such as the N400 and P600 arise as side effects of an error-based learning mechanism that explains linguistic adaptation and language learning. We instantiated this theory in a connectionist model that can simulate data from three studies on the N400 (amplitude modulation by expectancy, contextual constraint, and sentence position), five studies on the P600 (agreement, tense, word category, subcategorization and garden-path sentences), and a study on the semantic P600 in role reversal anomalies. Since ERPs are learning signals, this account explains adaptation of ERP amplitude to within-experiment frequency manipulations and the way ERP effects are shaped by word predictability in earlier sentences. Moreover, it predicts that ERPs can change over language development. The model provides an account of the sensitivity of ERPs to expectation mismatch, the relative timing of the N400 and P600, the semantic nature of the N400, the syntactic nature of the P600, and the fact that ERPs can change with experience. This approach suggests that comprehension ERPs are related to sentence production and language acquisition mechanisms.

Potential Mechanisms for the Ketamine-Induced Reduction of P3b Amplitudes.

In specific dosages, the N-methyl-D-aspartate receptor (NMDA) antagonist ketamine can be used to model transient psychotic symptoms in healthy individuals that resemble those of schizophrenia. Ketamine administration also temporarily impairs cognitive functions, which can be studied by event-related potentials (ERPs). ERPs also allow dissecting what stages of information processing are affected by ketamine and what stages remain functional. For tasks requiring the differentiation of targets and non-targets, it has repeatedly been shown that ketamine administration in healthy individuals leads to decreased amplitudes of the ERP component P3b in response to target stimuli. However, it could be argued that this ketamine-induced P3b reduction is the consequence of an increased difficulty to differentiate targets from non-targets, primarily mediated by ketamine's psychotomimetic rather than pharmacological effects. The current review of ERP studies seeks to clarify the issue whether P3b effects of ketamine may indeed be explained as the consequence of an experienced increase in task difficulty or whether alternative mechanisms are perhaps more plausible. The review first summarizes the effects of task difficulty on ERP components related to intentional stimulus categorization (P3b), involuntary attention switches to distractors (P3a), as well as sensory processing (P1, N1). Secondly, the ERP effects of task difficulty are contrasted with those observed in ketamine studies in healthy individuals. Findings show that P3b amplitudes are consistently diminished by an increased task difficulty, as well as after ketamine administration. In contrast and as most important difference, increased task difficulty leads to increased P3a amplitudes to distractors presented in same modality as targets, whereas ketamine leads to reduced P3a amplitudes for such distractors. This dissociation indicates that the decreased P3b amplitudes after ketamine cannot be explained by a drug-induced increase in task difficulty. The conjoint reductions of P3a and P3b amplitudes instead suggest that working memory operations, in particular working memory updating are impaired after ketamine, which is in line with previous behavioral findings.

Money or smiles: Independent ERP effects of associated monetary reward and happy faces.

In comparison to neutral faces, facial expressions of emotion are known to gain attentional prioritization, mainly demonstrated by means of event-related potentials (ERPs). Recent evidence indicated that such a preferential processing can also be elicited by neutral faces when associated with increased motivational salience via reward. It remains, however, an open question whether impacts of inherent emotional salience and associated motivational salience might be integrated. To this aim, expressions and monetary outcomes were orthogonally combined. Participants (N = 42) learned to explicitly categorize happy and neutral faces as either reward- or zero-outcome-related via an associative learning paradigm. ERP components (P1, N170, EPN, and LPC) were measured throughout the experiment, and separately analyzed before (learning phase) and after (consolidation phase) reaching a pre-defined learning criterion. Happy facial expressions boosted early processing stages, as reflected in enhanced amplitudes of the N170 and EPN, both during learning and consolidation. In contrast, effects of monetary reward became evident only after successful learning and in form of enlarged amplitudes of the LPC, a component linked to higher-order evaluations. Interactions between expressions and associated outcome were absent in all ERP components of interest. The present study provides novel evidence that acquired salience impacts stimulus processing but independent of the effects driven by happy facial expressions.

Associated valence impacts early visual processing of letter strings: Evidence from ERPs in a cross-modal learning paradigm.

Emotion effects in event-related potentials (ERPs) during reading have been observed at very short latencies of around 100 to 200 ms after word onset. The nature of these effects remains a matter of debate: First, it is possible that they reflect semantic access, which might thus occur much faster than proposed by most reading models. Second, it is possible that associative learning of a word's shape might contribute to the emergence of emotion effects during visual processing. The present study addressed this question by employing an associative learning paradigm on pronounceable letter strings (pseudowords). In a learning session, letter strings were associated with positive, neutral, or negative valence by means of monetary gain, loss, or zero outcome. Crucially, half of the stimuli were learned in the visual modality, while the other half was presented acoustically, allowing for experimental separation of associated valence and physical percept. In a test session one or two days later, acquired letter strings were presented in an old/new decision task while we recorded ERPs. Behavioural data showed an advantage for gain-associated stimuli both during learning and in the delayed old/new task. Early emotion effects in ERPs were limited to visually acquired letter strings, but absent for acoustically acquired letter strings. These results imply that associative learning of a word's visual features might play an important role in the emergence of emotion effects at the stage of perceptual processing.

Dissociating predictability, plausibility and possibility of sentence continuations in reading: evidence from late-positivity ERPs.

Late positive event-related potential (ERP) components occurring after the N400, traditionally linked to reanalysis due to syntactic incongruence, are increasingly considered to also reflect reanalysis and repair due to semantic difficulty. Semantic problems can have different origins, such as a mismatch of specific predictions based on the context, low plausibility, or even semantic impossibility of a word in the given context. DeLong, Quante & Kutas (2014) provided the first direct evidence for topographically different late positivities for prediction mismatch (left frontal late positivity for plausible but unexpected words) and plausibility violation (posterior-parietal late positivity for implausible, incongruent words). The aim of the current study is twofold: (1) to replicate this dissociation of ERP effects for plausibility violations and prediction mismatch in a different language, and (2) to test an additional contrast within implausible words, comparing impossible and possible sentence continuations. Our results replicate DeLong, Quante & Kutas (2014) with different materials in a different language, showing graded effects for predictability and plausibility at the level of the N400, a dissociation of plausible and implausible, anomalous continuations in posterior late positivities and an effect of prediction mismatch on late positivities at left-frontal sites. In addition, we found some evidence for a dissociation, at these left-frontal sites, between implausible words that were fully incompatible with the preceding discourse and those for which an interpretation is possible.

Influence of lag length on repetition priming in emotional stimuli: ERP evidence.

Previous studies have demonstrated both behavioral and neural evidence for the potential mediations of lag length and pre-existing memory representation on repetition priming. However, such mediations on emotional stimuli have not been described. The current experiment intended to disentangle lag length from pre-existing memory representation. A lexical decision task was performed, in which different emotional characters (either normal or transposed) were re-presented either immediately or delayed. In immediate repetition, one early and two late (ie, N400 and late positive complex) repetition-related event-related potential (ERP) effects were elicited, but these were not sensitive to pre-existing memory representation. The delayed repetition case merely observed the N400. These results suggest that the repetition-related priming effect is neutrally sensitive to lag length. Emotional information potentially exerts early and later influences in the processing underlying stimuli memory.

Atypical predictive processing during visual statistical learning in children with developmental dyslexia: an event-related potential study.

Previous research suggests that individuals with developmental dyslexia perform below typical readers on non-linguistic cognitive tasks involving the learning and encoding of statistical-sequential patterns. However, the neural mechanisms underlying such a deficit have not been well examined. The aim of the present study was to investigate the event-related potential (ERP) correlates of sequence processing in a sample of children diagnosed with dyslexia using a non-linguistic visual statistical learning paradigm. Whereas the response time data suggested that both typical and atypical readers learned the statistical patterns embedded in the task, the ERP data suggested otherwise. Specifically, ERPs of the typically developing children (n = 12) showed a P300-like response indicative of learning, whereas the children diagnosed with a reading disorder (n = 8) showed no such ERP effects. These results may be due to intact implicit motor learning in the children with dyslexia but delayed attention-dependent predictive processing. These findings are consistent with other evidence suggesting that differences in statistical learning ability might underlie some of the reading deficits observed in developmental dyslexia.

Neurophysiological indices of the effect of cognates on vowel perception in late Spanish-English bilinguals

It is well established that acquiring a second language (L2) later in life results in less accurate production and perception of speech sounds in the L2. An interesting question is to what extent phonological similarity of translation equivalents across the first language (L1) and L2 affects speech-sound processing and lexical access in an L2.The present study examined this question by comparing processing of Spanish-English translation equivalents that either were phonologically similar (cognates) or dissimilar (non-cognates) in fifteen monolingual English-speakers and 15 late Spanish-English bilinguals. Event related potentials (ERP) were used to examine whether late L2-learners had more difficulty discriminating mispronunciations of vowels in English words that have Spanish cognates compared to words that do not have cognates. Behavioral results indicated effects of language background and cognate status on discrimination, with bilinguals showing poorer discrimination of English vowel mispronunciations than the American-English monolingual control group. ERP results revealed that cognate words facilitated L2 phonological processing as evidenced by a larger frontal positive component (P400) ERP effect, similar in amplitude to the P400 from monolinguals. Results suggest that cognate words facilitate speech processing in adult L2 learners, and, thus, may also be useful as a tool for perceptual learning of L2 phonology.

Subject preference emerges as cross-modal strategy for linguistic processing

Research on spoken languages has identified a “subject preference” processing strategy for tackling input that is syntactically ambiguous as to whether a sentence-initial NP is a subject or object. The present study documents that the “subject preference” strategy is also seen in the processing of a sign language, supporting the hypothesis that the “subject”-first strategy is universal and not dependent on the language modality (spoken vs. signed). Deaf signers of Austrian Sign Language (ÖGS) were shown videos of locally ambiguous signed sentences in SOV and OSV word orders. Electroencephalogram (EEG) data indicated higher cognitive load in response to OSV stimuli (i.e. a negativity for OSV compared to SOV), indicative of syntactic reanalysis cost. A finding that is specific to the visual modality is that the ERP (event-related potential) effect reflecting linguistic reanalysis occurred earlier than might have been expected, that is, before the time point when the path movement of the disambiguating sign was visible. We suggest that in the visual modality, transitional movement of the articulators prior to the disambiguating verb position or co-occurring non-manual (face/body) markings were used in resolving the local ambiguity in ÖGS. Thus, whereas the processing strategy of “subject preference” is cross-modal at the linguistic level, the cues that enable the processor to apply that strategy differ in signing as compared to speech.

Electrophysiological Responses to Expectancy Violations in Semantic and Gambling Tasks: A Comparison of Different EEG Reference Approaches.

Dynamically evaluating the outcomes of our actions and thoughts is a fundamental cognitive ability. Given its excellent temporal resolution, the event-related potential (ERP) technology has been used to address this issue. The feedback-related negativity (FRN) component of ERPs has been studied intensively with the averaged linked mastoid reference method (LM). However, it is unknown whether FRN can be induced by an expectancy violation in an antonym relations context and whether LM is the most suitable reference approach. To address these issues, the current research directly compared the ERP components induced by expectancy violations in antonym expectation and gambling tasks with a within-subjects design and investigated the effect of the reference approach on the experimental effects. Specifically, we systematically compared the influence of the LM, reference electrode standardization technique (REST) and average reference (AVE) approaches on the amplitude, scalp distribution and magnitude of ERP effects as a function of expectancy violation type. The expectancy deviation in the antonym expectation task elicited an N400 effect that differed from the FRN effect induced in the gambling task; this difference was confirmed by all the three reference methods. Both the amplitudes of the ERP effects (N400 and FRN) and the magnitude as the expectancy violation increased were greater under the LM approach than those under the REST approach, followed by those under the AVE approach. Based on the statistical results, the electrode sites that showed the N400 and FRN effects critically depended on the reference method, and the results of the REST analysis were consistent with previous ERP studies. Combined with evidence from simulation studies, we suggest that REST is an optional reference method to be used in future ERP data analysis.

Event-Related Potential Responses to Task Switching Are Sensitive to Choice of Spatial Filter.

Event-related potential (ERP) studies using the task-switching paradigm show that multiple ERP components are modulated by activation of proactive control processes involved in preparing to repeat or switch task and reactive control processes involved in implementation of the current or new task. Our understanding of the functional significance of these ERP components has been hampered by variability in their robustness, as well as their temporal and scalp distribution across studies. The aim of this study is to examine the effect of choice of reference electrode or spatial filter on the number, timing and scalp distribution of ERP elicited during task-switching. We compared four configurations, including the two most common (i.e., average mastoid reference and common average reference) and two novel ones that aim to reduce volume conduction (i.e., reference electrode standardization technique (REST) and surface Laplacian) on mixing cost and switch cost effects in cue-locked and target-locked ERP waveforms in 201 healthy participants. All four spatial filters showed the same well-characterized ERP components that are typically seen in task-switching paradigms: the cue-locked switch positivity and target-locked N2/P3 effect. However, both the number of ERP effects associated with mixing and switch cost, and their temporal and spatial resolution were greater with the surface Laplacian transformation which revealed rapid temporal adjustments that were not identifiable with other spatial filters. We conclude that the surface Laplacian transformation may be more suited to characterize EEG signatures of complex spatiotemporal networks involved in cognitive control.

Individual differences in verbal working memory underlie a tradeoff between semantic and structural processing difficulty during language comprehension: An ERP investigation.

This study investigated the processes reflected in the widely observed N400 and P600 event-related potential (ERP) effects and tested the hypothesis that the N400 and P600 effects are functionally linked in a tradeoff relationship, constrained in part by individual differences in cognitive ability. Sixty participants read sentences, and ERP effects of semantic anomaly, relative to plausible words, were calculated for each participant. Results suggested qualitatively different ERP patterns across participants: Some individuals generated N400-dominated effects, whereas others generated P600-dominated effects, for the same stimuli. To specify the sources of individual differences in brain responses, we also derived aggregate scores for verbal working memory (WM), nonverbal WM, and language experience/knowledge, based on 6 behavioral measures administered to each participant. Multiple regression analysis pitting these 3 constructs against each other showed that a larger verbal WM capacity was significantly associated with larger P600 and smaller N400 effect amplitudes across individuals, whereas the other constructs did not predict the ERP effects. The results suggest that N400 and P600 brain responses, which may be attributable to semantic integration difficulty and structural processing, respectively, vie for expression when comprehenders encounter semantically unexpected words and that which option wins out is constrained in part by each comprehender's verbal WM capacity. (PsycINFO Database Record

On the processing of pragmatic information: ERP effects of emphasis processing

ABSTRACTThis study investigates the pragmatic processing of emphasis using the event-related potential (ERP) technique. Participant reads one-character and two-character mini-discourses, wherein the target name is either emphasised or not. Firstly, results show that the emphasised name elicited a larger P2 than the non-emphasised name, which suggests that emphasis modulates the attention of readers. Secondly, the emphasised name elicited a larger P300 than the non-emphasised name, which suggests that emphasis enhances online discourse integration. The emphasised condition on the sentence-final word elicited a smaller P300 than the non-emphasised condition in the two-character discourse, but not in the one-character discourse. This result suggests that the integration of emphasis information is facilitated by a contrastive character. Thus, the effect of emphasis may occur after the onset of the target word and end late with the integration of discourse information on the sentence-final words, which suggests that pragmatic processing is flexible.

Quantitative EEG and event-related potential P300 analysis oxiracetam injection curative effect in the treatment of delayed encephalopathy after acutecarbon monoxide poisoning

Objective: oevaluateclinical curative effect of oxiracetam injection in the treatment of delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) . Methods: Methods 52 patients with DEACMP were randomly divided into the observation group and the control group, 27 cases in the observation group and 25 cases in the control group. The 2 groups were adopted the treatment to improve the cerebral microcirculation and other symptomatic, the observation group on the basis of treatment for the treatment of oxiracetam Injection. Quantitative electroencephalogram (QEEG) and event-related potential P300 were used to evaluate the therapeutic effects of the 2 groups before and after treatment. Results: After treatment, QEEG value and event related potential P300 in observation group were decreased with statistically significant, respectively (P<0.05) , compared with the control group after treatment, the observation group excepted the occipital lobe, left parietal lobe, left around central and other indicators, QEEG and P300 oflatent period was shortened while the bank widens with statistical significance (P<0.05) . Conclusion: Olathe injection of DEACMP patients recovery have certain curative effect.

Individual differences in the processing of referential dependencies: Evidence from event-related potentials

The present study examines the processing of referential ambiguity and referential failure using event-related potentials (ERPs). Participants read sentences with pronouns (he, she) which contained either one, two, or no potential gender-matching antecedents. Participants also took tests of working memory (Count Span/Reading Span) and attentional control (Number Stroop). In contexts of referential ambiguity with two potential gender-matching antecedents, two different responder types emerged, with some participants yielding a sustained negativity (Nref) and others a sustained positivity. For individuals who elicited Nref, the size of the effect was related to working memory such that higher Count Span scores were related to a larger Nref. For individuals who elicited a positivity, the effect was marginally related to attentional control such that better performance on the Stroop was related to a less positive, or increasingly negative-going ERP effect. Contexts of referential failure, with no gender-matching antecedents, yielded P600 for all participants, suggesting that participants may treat the failure of the pronoun to agree in gender with the antecedents as a violation despite the absence of an explicit acceptability judgment task.

An ERP study of multidimensional source retrieval in depression

We collected event-related potentials (ERPs) from 24 unmedicated adults with Major Depressive Disorder (MDD) and 24 controls during source memory retrieval. Words were encoded on the left or right during animacy and mobility judgments. Mobility judgments were slower than animacy judgments, suggesting deeper encoding. Participants then recalled the encoding judgment (Question cue) and position (Side cue) for each word. Depressed adults, but not controls, showed better accuracy for words from the mobility task presented under the Question vs. Side Cue. Furthermore, depressed adults showed larger left parietal ERPs to words from the mobility task presented under the Question vs. the Side Cue from 400 to 800 ms and 800–1400 ms. This ERP effect was negatively correlated with sleep quality. Thus, deep encoding followed by retrieval of the encoding judgment supported memory in MDD and augmented left parietal ERPs that have been linked to recollection and that appear sensitive to sleep disturbance.

Neural mechanisms underlying successful and deficient multi-component behavior in early adolescent ADHD.

Attention Deficit Hyperactivity Disorder (ADHD) is a disorder affecting cognitive control. These functions are important to achieve goals when different actions need to be executed in close succession. This type of multi-component behavior, which often further requires the processing of information from different modalities, is important for everyday activities. Yet, possible changes in neurophysiological mechanisms have not been investigated in adolescent ADHD. We examined N = 31 adolescent ADHD patients and N = 35 healthy controls (HC) in two Stop-Change experiments using either uni-modal or bi-modal stimuli to trigger stop and change processes. These stimuli were either presented together (SCD0) or in close succession of 300 milliseconds (SCD300). Using event-related potentials (ERP), EEG data decomposition and source localization we analyzed neural processes and functional neuroanatomical correlates of multicomponent behavior. Compared to HCs, ADHD patients had longer reaction times and higher error rates when Stop and Change stimuli were presented in close succession (SCD300), but not when presented together (SCD0). This effect was evident in the uni-modal and bi-modal experiment and is reflected by neurophysiological processes reflecting response selection mechanisms in the inferior parietal cortex (BA40). These processes were only detectable after accounting for intra-individual variability in neurophysiological data; i.e. there were no effects in standard ERPs. Multi-component behavior is not always deficient in ADHD. Rather, modulations in multi-component behavior depend on a critical temporal integration window during response selection which is associated with functioning of the inferior parietal cortex. This window is smaller than in HCs and independent of the complexity of sensory input.

Processing of emotional information in written language

Language conveys both semantic and emotional information. Emotional processing in language could not be easily explained by the current word recognition model, sentence processing model and discourse comprehension model. In order to uncover the characteristics of emotional processing in written language, the present review attempted to integrate findings from behavioral, event-related potential (ERP), and functional magnetic resonance imagining (fMRI) studies on emotional processing at multiple scales, such as words, sentences and discourses levels. First, previous studies have shown both automatic and controlled processes at different stages of emotional words processing. Some early ERP effects (before 300 ms: such as N1/P1, P2, EPN) as well as the activation of subcortical region (such as amygdala) have been taken as evidences for the rapid and automatic emotional processing. Some late ERP effects (such as late positive component after 500 ms) and the recruitment of higher-order brain areas (such as medial prefrontal cortex and cingulate cortex) have been suggested to reflect the controlled processing of the emotion words. In addition, emotional connotation could enhance cortical responses at all stages of visual word processing such as the assembly of visual word form (up to 200 ms), semantic access (around 200 ms), allocation of attentional resources (around 300 ms), contextual analysis (around 400 ms), and sustained processing (around 500 ms). Moreover, the network of word reading is influenced by the emotional network as manifested by the enhanced engagement of lexical-semantic network when processing emotional words compared to neutral words. However, it remains unclear regarding the time locus of emotional effect with respect to the lexical access. Another important finding is that emotional words obtained prioritized processing no matter when they were presented in isolation or shown in contexts. The salience of emotion information could override detailed semantic analysis, as indicated by the lack of semantic violation effect when the violations occurred to emotion words. Also, the emotional dimension of sentences was prioritized when the emotional words were embedded in sentences, as indicated by the N400 effect to emotion words following neutral congruent contexts. Moreover, the influence of emotional word on sentence processing was sustained, as suggested by its influence on the processing of its following words in sentences. Finally, we showed that emotion can be induced directly by emotional words or implied by a series of neutral words (for example, ″The boy fell asleep and never woke up again″). Both types of emotional sentences activated emotional brain network (such as amygdala, insula, medial prefrontal cortex), which in turn enhanced the involvement of language network (such as inferior frontal gyrus, middle temporal gyrus) compared to neutral sentences. Therefore, the language and emotional networks are highly interactive. Overall, the current review summarized main findings regarding emotional processing in written language. We have shown that the study of emotional processing in language has significant importance for psycholinguistics and affective neuroscience. We proposed that it might be a useful approach to investigate emotional language processing from an embodiment perspective. Future studies could further investigate the functional connectivity of the emotional and language networks.

Taking off the training wheels: Measuring auditory P3 during outdoor cycling using an active wet EEG system

Mobile EEG allows the investigation of brain activity in increasingly complex environments. In this study, EEG equipment was adapted for use and transportation in a backpack while cycling. Participants performed an auditory oddball task while cycling outside and sitting in an isolated chamber inside the lab. Cycling increased EEG noise and marginally diminished alpha amplitude. However, this increased noise did not influence the ability to measure reliable event related potentials (ERP). The P3 was similar in topography, and morphology when outside on the bike, with a lower amplitude in the outside cycling condition. There was only a minor decrease in the statistical power to measure reliable ERP effects. Unexpectedly, when biking outside significantly decreased P2 and increased N1 amplitude were observed when evoked by both standards and targets compared with sitting in the lab. This may be due to attentional processes filtering the overlapping sounds between the tones used and similar environmental frequencies. This study established methods for mobile recording of ERP signals. Future directions include investigating auditory P2 filtering inside the laboratory.

Investigating the Functional Utility of the Left Parietal ERP Old/New Effect: Brain Activity Predicts within But Not between Participant Variance in Episodic Recollection.

A success story within neuroimaging has been the discovery of distinct neural correlates of episodic retrieval, providing insight into the processes that support memory for past life events. Here we focus on one commonly reported neural correlate, the left parietal old/new effect, a positive going modulation seen in event-related potential (ERP) data that is widely considered to index episodic recollection. Substantial evidence links changes in the size of the left parietal effect to changes in remembering, but the precise functional utility of the effect remains unclear. Here, using forced choice recognition of verbal stimuli, we present a novel population level test of the hypothesis that the magnitude of the left parietal effect correlates with memory performance. We recorded ERPs during old/new recognition, source accuracy and Remember/Know/Guess tasks in two large samples of healthy young adults, and successfully replicated existing within participant modulations of the magnitude of the left parietal effect with recollection. Critically, however, both datasets also show that across participants the magnitude of the left parietal effect does not correlate with behavioral measures of memory – including both subjective and objective estimates of recollection. We conclude that in these tasks, and across this healthy young adult population, the generators of the left parietal ERP effect do not index performance as expected. Taken together, these novel findings provide important constraints on the functional interpretation of the left parietal effect, suggesting that between group differences in the magnitude of old/new effects cannot always safely be used to infer differences in recollection.