Analysis Of Event-related Potentials Data Research Articles

Exploring Attention Bias Mechanisms in Sub-Threshold Depression: ERP Insights into Biased Orientation and Disengagement

Individuals with depression may have alterations in attention that begin at the sub-threshold stage. This study explored attention bias from the perspectives of early attention orientation and late attention disengagement in individuals with sub-threshold depression (SD) and healthy control (HC) individuals using a cue-target paradigm and event-related potentials (ERPs). The study enrolled 46 participants, comprising 23 males and 23 females, with 25 individuals in the SD group and 21 in the HC group, exceeding the calculated sample size requirement. The data were analyzed from two aspects. Behavioral data showed that SD individuals had difficulty in attention disengagement and that the time of attention transfer was delayed. Analysis of ERP data revealed that, regardless of the attributes of the emotional stimulus, the cue information promoted participants’ response to the target stimulus. While SD individuals did show directional acceleration of attention to the emotional stimulus, no significant negative attention bias was observed. Taken together, these findings suggest that SD individuals do not show specific directional acceleration of attention to negative stimuli in the early stage of attention processing, although there may be attention avoidance.

Using event-related potentials to identify user's moods induced by product color stimuli with different attributes

Color is an important factor affecting users’ moods. Exploring the effect of product colors on users’ moods is key for improving users’ mood experience. Here, Electroencephalogram (EEG) technology was used to study the relationship between users’ moods and product colors. Participants evaluated color images of electric hand drills, and the effect of color system and hue relationship was studied. The mood perception states were obtained based on the participants’ subjective assessment; the results of time–frequency analysis and event-related potentials (ERPs) based on synchronously collected EEG signals were also obtained. Mood data sets related to product color attributes were obtained through analysis of behavioral data and ERPs data. Results of the behavioral experiment showed that the participants were more sensitive to color system than hue relationship. Warm color systems and identity hue relationships elicited more positive moods; the mood’s directions of participants for neutral color systems, similarity and gray color hue relationships were ambiguous, and reaction times were longer. The results of the time–frequency analysis showed that there were obvious ERPs between 100 and 400 ms after stimuli appeared. The results of the ERPs analysis showed that negative stimuli caused significant changes in the amplitude of components N2 and P3, positive stimuli caused it in the amplitude of P3, and neutral stimuli caused it in the amplitude of N400. The results of our study provide accurate quantitative data that can be used to understand the relationship between users’ moods and product colors; these data will aid future product color design research.

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.

Electrophysiological Correlates of Change Detection during Delayed Matching Task: A Comparison of Different References.

Detecting the changed information between memory representation and incoming sensory inputs is a fundamental cognitive ability. By offering the promise of excellent temporal resolution, event-related potential (ERP) technique has served as a primary tool for studying this process with reference of the linked mastoid (LM). However, given that LM may distort the ERP signals, it is still undetermined whether LM is the best reference choice. The goal of the current study was to systematically compare LM, reference electrode standardization technique (REST) and average reference (AR) for assessing the ERP correlates of change detection during a delayed matching task. Colored shapes were adopted as materials while both the task-relevant shape feature and -irrelevant color feature could be changed. The results of the ERP amplitude showed that both of the task-relevant and -conjunction feature changes elicited significantly more positive posterior P2 in REST and AR, but not in LM. Besides, significantly increased N270 was observed in task-relevant and -conjunction feature changes in both the REST and LM, but in the conjunction feature change in AR. Only the REST-obtained N270 revealed a significant increment in task-irrelevant feature change, which was compatible with the delayed behavioral performance. Statistical parametric scalp mapping (SPSM) results showed a left posterior distribution for AR, an anterior distribution for LM, and both the anterior and left posterior distributions for REST. These results indicate that different types of references may provide distinct cognitive interpretations. Interestingly, only the SPSM of REST was consistent with previous fMRI findings. Combined with the evidence of simulation studies and the current observations, we take the REST-based results as the objective one, and recommend using REST technology in the future ERP data analysis.

Neural dynamics of cognitive flexibility: spatiotemporal analysis of event-related potentials

To explore the neural dynamics during alternating task switching. In an alternating-runs paradigm, 23 healthy volunteers were asked to categorize Arabic numerals displayed on the screen into either even or odd numbers or judge if the number was greater than 5 according its color cues. The color of the numerals were regularly switched every three trials (switch, nested and pre-switch trials). ANOVA of repeated-measure and paired t-test were used for analysis of the behavioral performance and event-related potential (ERP) data of 19 channels, and statistical parametric mapping of F and t values was used to reveal the spatiotemporal patterns of ERP. Significant switch costs (switch versus nested trial) were found in the mean reaction time (123.61∓83.84 ms, P<0.05) and the mean accuracy [(1.24∓3.30)%, P<0.05]. Statistical parametric mapping of t value of ERP suggested that the switch effects appeared in the right frontal-parietal network and then in the left one. The preparation effects appeared in the right frontal pole followed by the left one, both accompanied by the activation of the posterior regions. Cognitive flexibility depends on the dynamic activation of the fronto-parietal network. The frontal poles are involved in the pre-switch preparatory process, the dorsal frontal areas are related with the actual switch process, and the left and right frontal regions play different roles.

A Comparative Study of Average, Linked Mastoid, and REST References for ERP Components Acquired during fMRI.

In simultaneous electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) studies, average reference (AR), and digitally linked mastoid (LM) are popular re-referencing techniques in event-related potential (ERP) analyses. However, they may introduce their own physiological signals and alter the EEG/ERP outcome. A reference electrode standardization technique (REST) that calculated a reference point at infinity was proposed to solve this problem. To confirm the advantage of REST in ERP analyses of synchronous EEG-fMRI studies, we compared the reference effect of AR, LM, and REST on task-related ERP results of a working memory task during an fMRI scan. As we hypothesized, we found that the adopted reference did not change the topography map of ERP components (N1 and P300 in the present study), but it did alter the task-related effect on ERP components. LM decreased or eliminated the visual working memory (VWM) load effect on P300, and the AR distorted the distribution of VWM location-related effect at left posterior electrodes as shown in the statistical parametric scalp mapping (SPSM) of N1. ERP cortical source estimates, which are independent of the EEG reference choice, were used as the golden standard to infer the relative utility of different references on the ERP task-related effect. By comparison, REST reference provided a more integrated and reasonable result. These results were further confirmed by the results of fMRI activations and a corresponding EEG-only study. Thus, we recommend the REST, especially with a realistic head model, as the optimal reference method for ERP data analysis in simultaneous EEG-fMRI studies.

Behavioral and Electrophysiological Correlates of Memory Binding Deficits in Patients at Different Risk Levels for Alzheimer's Disease.

Deficits in visual short-term memory (VSTM) binding have been proposed as an early and specific marker for Alzheimer's disease (AD). However, no studies have explored the neural correlates of this domain in clinical categories involving prodromal stages with different risk levels of conversion to AD. We assessed underlying electrophysiological modulations in patients with mild cognitive impairment (MCI), patients in the MCI stages of familial AD carrying the mutation E280A of the presenilin-1 gene (MCI-FAD), and healthy controls. Moreover, we compared the behavioral performance and neural correlates of both patient groups. Participants completed a change-detection VSTM task assessing recognition of changes between shapes or shape-color bindings, presented in two consecutive arrays (i.e., study and test) while event related potentials (ERPs) were recorded. Changes always occurred in the test array and consisted of new features replacing studied features (shape-only) or features swapping across items (shape-color binding). Both MCI and MCI-FAD patients performed worse than controls in the shape-color binding condition. Early electrophysiological activity (100-250 ms) was significantly reduced in both clinical groups, particularly over fronto-central and parieto-occipital regions. However, shape-color binding performance and their reduced neural correlates were similar between MCI and MCI-FAD. Our results support the validity of the VSTM binding test and their neural correlates in the early detection of AD and highlight the importance of studies comparing samples at different risk for AD conversion. The combined analysis of behavioral and ERP data gleaned with the VSTM binding task can offer a valuable memory biomarker for AD.

Spatio-temporal common pattern: A companion method for ERP analysis in the time domain

BackgroundAlready used at the incept of research on event-related potentials (ERP) over half a century ago, the arithmetic mean is still the benchmark for ERP estimation. Such estimation, however, requires a large number of sweeps and/or a careful rejection of artifacts affecting the electroencephalographic recording. New methodIn this article we propose a method for estimating ERPs as they are naturally contaminated by biological and instrumental artifacts. The proposed estimator makes use of multivariate spatio-temporal filtering to increase the signal-to-noise ratio. This approach integrates a number of relevant advances in ERP data analysis, such as single-sweep adaptive estimation of amplitude and latency and the use of multivariate regression to account for ERP overlapping in time. ResultsWe illustrate the effectiveness of the proposed estimator analyzing a dataset comprising 24 subjects involving a visual odd-ball paradigm, without performing any artifact rejection. Comparison with existing method(s)As compared to the arithmetic average, a lower number of sweeps is needed. Furthermore, artifact rejection can be performed roughly using permissive automatic procedures. ConclusionThe proposed ensemble average estimator yields a reference companion to the arithmetic ensemble average estimation, suitable both in clinical and research settings. The method can be applied equally to event related fields (ERF) recorded by means of magnetoencephalography. In this article we describe all necessary methodological details to promote testing and comparison of this proposed method by peers. Furthermore, we release a MATLAB toolbox, a plug-in for the EEGLAB software suite and a stand-alone executable application.

Contingent negative variation (CNV) associated with sensorimotor timing error correction

IntroductionDetection and subsequent correction of sensorimotor timing errors are fundamental to adaptive behavior. Using scalp-recorded event-related potentials (ERPs), we sought to find ERP components that are predictive of error correction performance during rhythmic movements. MethodHealthy right-handed participants were asked to synchronize their finger taps to a regular tone sequence (every 600ms), while EEG data were continuously recorded. Data from 15 participants were analyzed. Occasional irregularities were built into stimulus presentation timing: 90ms before (advances: negative shift) or after (delays: positive shift) the expected time point. A tapping condition alternated with a listening condition in which identical stimulus sequence was presented but participants did not tap. ResultsBehavioral error correction was observed immediately following a shift, with a degree of over-correction with positive shifts. Our stimulus-locked ERP data analysis revealed, 1) increased auditory N1 amplitude for the positive shift condition and decreased auditory N1 modulation for the negative shift condition; and 2) a second enhanced negativity (N2) in the tapping positive condition, compared with the tapping negative condition. In response-locked epochs, we observed a CNV (contingent negative variation)-like negativity with earlier latency in the tapping negative condition compared with the tapping positive condition. This CNV-like negativity peaked at around the onset of subsequent tapping, with the earlier the peak, the better the error correction performance with the negative shifts while the later the peak, the better the error correction performance with the positive shifts. DiscussionThis study showed that the CNV-like negativity was associated with the error correction performance during our sensorimotor synchronization study. Auditory N1 and N2 were differentially involved in negative vs. positive error correction. However, we did not find evidence for their involvement in behavioral error correction. Overall, our study provides the basis from which further research on the role of the CNV in perceptual and motor timing can be developed.

Method for exploratory cluster analysis and visualisation of single-trial ERP ensembles

BackgroundThe validity of ensemble averaging on event-related potential (ERP) data has been questioned, due to its assumption that the ERP is identical across trials. Thus, there is a need for preliminary testing for cluster structure in the data. New methodWe propose a complete pipeline for the cluster analysis of ERP data. To increase the signal-to-noise (SNR) ratio of the raw single-trials, we used a denoising method based on Empirical Mode Decomposition (EMD). Next, we used a bootstrap-based method to determine the number of clusters, through a measure called the Stability Index (SI). We then used a clustering algorithm based on a Genetic Algorithm (GA) to define initial cluster centroids for subsequent k-means clustering. Finally, we visualised the clustering results through a scheme based on Principal Component Analysis (PCA). ResultsAfter validating the pipeline on simulated data, we tested it on data from two experiments – a P300 speller paradigm on a single subject and a language processing study on 25 subjects. Results revealed evidence for the existence of 6 clusters in one experimental condition from the language processing study. Further, a two-way chi-square test revealed an influence of subject on cluster membership. Comparison with existing method(s)Our analysis operates on denoised single-trials, the number of clusters are determined in a principled manner and the results are presented through an intuitive visualisation. ConclusionsGiven the cluster structure in some experimental conditions, we suggest application of cluster analysis as a preliminary step before ensemble averaging.

Study on Game Theory and Model of ERP based on EEG

Decision-making process refers in a particular situation, and choosing from several existing optional strategy evaluation process of certain strategy, however, in a complex environment, individual decisions tend to be affected by other individuals and random change of strategy, thus it is difficult to make a best decision. Although game theory provides a variety of decision-making plan, but it is not clear how the decision is influenced by the experience. The best decision-making behaviors need flexible adjustment strategy accord to the recent gains. In order to explore the nature of the human decision-making process USES the zero-sum game COINS of the positive and negative game, assuming that flexibility was produced in the process of reinforcement learning and a reinforcement learning model is established. In addition, the entire record the event related potential in the process of the subjects in the experiment. Analysis of ERP (Event Related Potential) data mainly focus on feedback related negative wave, which was considered to reflect the error signal and benefit related to the brain potential. Results show that after the loss to the other party of the event related potential amplitude suggested that participants would change the policy of pushing in the subsequent regulations, and the result was satisfied.

Neural effects of cognitive control load on auditory selective attention

Whether and how working memory disrupts or alters auditory selective attention is unclear. We compared simultaneous event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) responses associated with task-irrelevant sounds across high and low working memory load in a dichotic-listening paradigm. Participants performed n-back tasks (1-back, 2-back) in one ear (Attend ear) while ignoring task-irrelevant speech sounds in the other ear (Ignore ear). The effects of working memory load on selective attention were observed at 130–210ms, with higher load resulting in greater irrelevant syllable-related activation in localizer-defined regions in auditory cortex. The interaction between memory load and presence of irrelevant information revealed stronger activations primarily in frontal and parietal areas due to presence of irrelevant information in the higher memory load. Joint independent component analysis of ERP and fMRI data revealed that the ERP component in the N1 time-range is associated with activity in superior temporal gyrus and medial prefrontal cortex. These results demonstrate a dynamic relationship between working memory load and auditory selective attention, in agreement with the load model of attention and the idea of common neural resources for memory and attention.

The neurophysiological performance of visuospatial working memory in children with developmental coordination disorder

The objective of this study was to investigate the mechanisms underlying the deficit in visuospatial working memory (VSWM) seen in children with developmental coordination disorder (DCD) and to compare brain activity while performing a VSWM task in children with DCD and typically developing children. Behavioural performance and event-related potentials (ERPs) were recorded in 24 children (12 males, 12 females; mean age 139 mo, SD 4 mo) with DCD (as determined by a score <5th centile on the Movement Assessment Battery for Children - Second Edition) and in 30 age- and sex-matched typically developing children (15 males; 15 females; mean age 140 mo, SD 5 mo) recruited from local schools, while performing one spatial non-delay and two time-delayed spatial memory tasks. Compared with typically developing children, children with DCD exhibited longer reaction times (p = 0.022; partial η(2) =0.10) and lower accuracy rates (p < 0.001; partial η(2) = 0.35) on the two spatial memory tasks. Electrophysiological indices also showed distinct modulatory effects, with children with DCD exhibiting smaller P3 (p < 0.001; partial η(2) = 0.26) and positive slow wave (pSW; p = 0.003; partial η(2) = 0.16) amplitude and a smaller area under the curve of P3 and pSW components (p = 0.002; partial η(2) = 0.17). The combined analysis of behavioural performance and ERP data suggests that children with DCD have deficits of visuospatial working memory owing to fewer resources being allocated to comparison of spatial locations, less effort allotted to the response selection, and less neural processing employed during the retrieval process phase.

A factor-adjusted multiple testing procedure for ERP data analysis

Event-related potentials (ERPs) are now widely collected in psychological research to determine the time courses of mental events. When event-related potentials from treatment conditions are compared, often there is no a priori information on when or how long the differences should occur. Testing simultaneously for differences over the entire set of time points creates a serious multiple comparison problem in which the probability of false positive errors must be controlled, while maintaining reasonable power for correct detection. In this work, we extend the factor-adjusted multiple testing procedure developed by Friguet, Kloareg, and Causeur (Journal of the American Statistical Association, 104, 1406-1415, 2009) to manage the multiplicity problem in ERP data analysis and compare its performance with that of the Benjamini and Hochberg (Journal of the Royal Statistical Society B, 57, 289-300, 1995) false discovery rate procedure, using simulations. The proposed procedure outperformed the latter in detecting more truly significant time points, in addition to reducing the variability of the false discovery rate, suggesting that corrections for mass multiple testings of ERPs can be much improved by modeling the strong local temporal dependencies.

Electrocortical correlates of intra-subject variability in reaction times: Average and single-trial analyses

Intra-subject variability of reaction times (ISV), generally considered secondary to measures of central tendency, has become increasingly important for cognitive neuroscience. Event-related potential (ERP) research suggests an inverse relationship between ISV and P3b amplitude; however ERP methods’ reliance on averaged waveforms may be unsuitable for studying ISV due to potentially distorting effects of latency jitter. The present study investigates the neural bases of ISV through single-trial analysis of P3bs in groups with low and high ISV, using Infomax-rotated principal components analysis of ERP data. Results indicate that while latency jitter contributes to the reduced P3b amplitude seen in average ERPs of high ISV participants, group differences in amplitude survive the use of single-trial methods that are robust to such distortions. A decoupling of P3b and RT was also seen in the high ISV group. The results are discussed in the context of the P3b's dimensionality, and its possible catecholaminergic underpinnings.

Electrophysiological correlates of retrieval orientation in reality monitoring

Retrieval orientation describes the modulation in the processing of retrieval cues by the nature of the targeted material in memory. Retrieval orientation is usually investigated by analyzing the cortical responses to new (unstudied) material when different memory contents are targeted. This approach avoids confounding effects of retrieval success. We investigated the neural correlates of retrieval orientation in reality monitoring with event-related potentials (ERPs) and assessed the impact of retrieval accuracy on obtained ERP measures. Thirty-two subjects studied visually presented object names that were followed either by a picture of that object (perceived condition) or by the instruction to mentally generate such a picture (imagine condition). Subsequently, subjects had to identify object names of one study condition and reject object names of the second study condition together with newly presented object names. The data analysis showed that object names were more accurately identified when they had been presented in the perceived condition. Two topographically distinct ERP effects of retrieval orientation were revealed: From 600 to 1100ms after stimulus representation, ERPs were more positive at frontal electrode sites when object names from the imagine condition were targeted. The analysis of response-locked ERP data revealed an additional effect at posterior electrode sites, with more negative ERPs shortly after response onset when items from the imagine condition were targeted. The ERP effect at frontal electrode sites, but not at posterior electrode sites was modulated by relative memory accuracy, with stronger effects in subjects who had lower memory accuracy for items of the imagine condition. The findings are suggestive for a contribution of frontal brain areas to retrieval orientation processes in reality monitoring and indicate that neural correlates of retrieval orientation can be modulated by retrieval effort, with stronger activation of these correlates with increasing task demands.

Neural signs of flexible categorization: Evidence from the flexibility of inclusion of humans in animal/non-animal categorization

The temporal course of the human brain dealing with flexible categorization was analyzed by using an event-related potential (ERP) technique in an animal/non-animal categorization task in two parallel experiments. Participants shown animal, person, mixed and non-animal images were asked if they saw ‘animals’ after being instructed to exclude humans in the category of ‘animals’ in Experiment 1, while they were told to define humans as animals in Experiment 2. The ERP data analysis showed that targets elicited larger P150 amplitudes than non-targets, which may reflect early perceptual detection and selection. Images including humans (person and mixed images) elicited larger anterior N2 amplitudes than animal images, regardless of the polysemy of the animal category, which may reflect an extra load on attention and monitoring processes in flexible categorization. Compared to non-targets, targets elicited larger P3 amplitudes, which may be associated with the categorical decision process.

The ERP PCA Toolkit: An open source program for advanced statistical analysis of event-related potential data

This article presents an open source Matlab program, the ERP PCA (EP) Toolkit, for facilitating the multivariate decomposition and analysis of event-related potential data. This program is intended to supplement existing ERP analysis programs by providing functions for conducting artifact correction, robust averaging, referencing and baseline correction, data editing and visualization, principal components analysis, and robust inferential statistical analysis. This program subserves three major goals: (1) optimizing analysis of noisy data, such as clinical or developmental; (2) facilitating the multivariate decomposition of ERP data into its constituent components; (3) increasing the transparency of analysis operations by providing direct visualization of the corresponding waveforms.

False discovery rate and permutation test: An evaluation in ERP data analysis

Current analysis of event-related potentials (ERP) data is usually based on the a priori selection of channels and time windows of interest for studying the differences between experimental conditions in the spatio-temporal domain. In this work we put forward a new strategy designed for situations when there is not a priori information about 'when' and 'where' these differences appear in the spatio-temporal domain, simultaneously testing numerous hypotheses, which increase the risk of false positives. This issue is known as the problem of multiple comparisons and has been managed with methods that control the false discovery rate (FDR), such as permutation test and FDR methods. Although the former has been previously applied, to our knowledge, the FDR methods have not been introduced in the ERP data analysis. Here we compare the performance (on simulated and real data) of permutation test and two FDR methods (Benjamini and Hochberg (BH) and local-fdr, by Efron). All these methods have been shown to be valid for dealing with the problem of multiple comparisons in the ERP analysis, avoiding the ad hoc selection of channels and/or time windows. FDR methods are a good alternative to the common and computationally more expensive permutation test. The BH method for independent tests gave the best overall performance regarding the balance between type I and type II errors. The local-fdr method is preferable for high dimensional (multichannel) problems where most of the tests conform to the empirical null hypothesis. Differences among the methods according to assumptions, null distributions and dimensionality of the problem are also discussed.

Mechanisms of deficit of visuospatial attention shift in children with developmental coordination disorder: A neurophysiological measure of the endogenous Posner paradigm

The purpose of this study was to investigate and compare the mechanisms of brain activity, as revealed by a combination of the visuospatial attention shifting paradigm and event-related potentials (ERP) in children with developmental coordination disorder (DCD) and typically developing children. Twenty-eight DCD children and 26 typically developing children were recorded with regard to their behavioral performance and ERP measures during a variant of the endogenous Posner paradigm, in which they should react to visual targets preceded by spatial cues or presented uncued. Children with DCD showed longer reaction time and a deficit in inhibitory response capacity when compared to typically developing children. The electrophysiological characteristics also showed distinct modulatory effects upon attentional orienting, anticipatory mechanisms, and cognitive-to-motor transfer in children with DCD: longer cue-P3 and target-N1 latency, smaller target-P3 amplitude, an elongated interval between N2 and the motor response (N2-RT), and small areas on contingent negative variation (CNV). The combined analysis of behavioral performance and ERP data suggested that children with DCD had deficits of slower target identification (N1), less ability in interhemispheric (P3) and cognitive-to-motor transfer speed (N2-RT), as well as a less mature anticipatory and executive process (CNV).