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 4,687 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

"Component" notions inherently used with measurement approaches, raw peak determination, PCA and generator approaches are discussed. By combining aspects of them all, a new model of ERP decomposition is established; quite profitable and surprising mathematical properties are illustrated and discussed.
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PMID:Decomposing event-related potentials: a new topographic components model. 320 83

Although female/male cognitive differences have been studied for some time, little is known about such differences relative to music. Highly-trained musicians (15 females and 15 males) performed a memory task for musical timbre modeled after the missing-displaced visual object test known to favor female performance. Subjects were tested on memory for a timbre missing from a previously presented set of synthesized instrumental timbres, and a control series of white noise bursts at two different intensity levels. Subjects were given the missing-displaced visual object test and ERPs were recorded from three midline sites and two lateral sites. Waveforms were subjected to a principal component analysis and analysis of variance. Females and males performed equally well on both of the auditory series and the visual object test. Both auditory series elicited several ERP components: a strong early peak to the white noise, and both early (P3a) and late (P3b) peaks to the timbre series. PCA factor, maximum at 675 ms (P3b), showed a main effect for sex across both series with males > females. PCA factor, maximum at 336 ms (P3a), showed larger Fz to Pz differential for females than males for both auditory series. Females show a greater differentiation between targets and nontargets in the white noise series, suggesting greater sensitivity to changes in intensity. Interactions involving absolute pitch also appeared in the sensory processing time frames. Although the behavioral measures did not show significant sex differences, the ERP measures did show reliable task-related sex differences.
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PMID:Sex differences in memory for timbre: an event-related potential study. 891 17

Falkenstein, Hohnsbein, and Hoorman (1994) suggested that common measures of P300 latency confound a "P-SR" component whose latency corresponds to stimulus evaluation time and a "P-CR" component whose latency varies with response-selection time, thus casting doubt on work in mental chronometry that relies on P300 latency. We report here a replication and extension of Falkenstein et al. (1994) using a high-density 129-electrode montage with 11 subjects. Spatiotemporal PCA was used to extract the components of the ERP. A centroid measure is also introduced for detecting waveform-timing changes beyond just peak latency. In terms of componentry, we argue that the P-SR and the P-CR, correspond to the P3a/Novelty P3 and the P300, respectively. Conceptually, we dispute the proposed distinction between stimulus evaluation and response selection. We suggest a four-stage ERP model of information processing and place the P3a and the P300 in this framework.
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PMID:Parsing the late positive complex: mental chronometry and the ERP components that inhabit the neighborhood of the P300. 1531 73

To disentangle subprocesses of verbal working memory deficits in schizophrenia, long EEG epochs (>10 s) were recorded from 13 patients and 17 healthy adults during a visual word serial position test. ERP generator patterns were summarized by temporal PCA from reference-free current source density (CSD) waveforms to sharpen 31-channel topographies. Patients showed poorer performance and reduced left inferior parietotemporal P3 source. Build-up of mid-frontal negative slow wave (SW) in controls during item encoding, integration, and active maintenance was absent in patients, whereas a sustained mid-frontal SW sink during the retention interval was comparable across groups. Mid-frontal SW sinks (encoding and retention periods) and posterior SW sinks and sources (encoding only) were related to performance in controls only. Data suggest disturbed processes in a frontal-parietotemporal network in schizophrenia, affecting encoding and early item storage.
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PMID:ERP/CSD indices of impaired verbal working memory subprocesses in schizophrenia. 1680 62

To clarify polarity, topography, and time course of recognition memory ERP old/new effects during matched visual and auditory continuous word recognition tasks, unrestricted temporal PCA jointly analyzed stimulus- and response-locked, reference-free current source densities (31-channel, N=40). Randomization tests provided unbiased statistics for complete factor topographies. Old/new left parietal source effects were complemented by lateral frontocentral sink effects in both modalities, overlapping modality-specific P3 sources 160 ms preresponse. A mid-frontal sink 45 ms postresponse terminated the frontoparietal generator pattern, showed old/new effects consistent with bilateral activation of anterior cingulate and SMA, and preceded similar activity extending posteriorly along the longitudinal fissure. These methods separated old/new stimulus source (preresponse) and response sink (postresponse) effects from motor and modality-specific ERPs.
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PMID:Reference-independent ERP old/new effects of auditory and visual word recognition memory: Joint extraction of stimulus- and response-locked neuronal generator patterns. 1764 Feb 66

Event-related potentials (31-channel ERPs) were recorded from 38 depressed, unmedicated outpatients and 26 healthy adults (all right-handed) in tonal and phonetic oddball tasks developed to exploit the perceptual challenge of a dichotic stimulation. Tonal nontargets were pairs of complex tones (corresponding to musical notes G and B above middle C) presented simultaneously to each ear (L/R) in an alternating series (G/B or B/G; 2-s fixed SOA). A target tone (note A) replaced one of the pair on 20% of the trials (A/B, G/A, B/A, A/G). Phonetic nontargets were L/R pairs of syllables (/ba/, /da/) with a short voice onset time (VOT), and targets contained a syllable (/ta/) with a long VOT. Subjects responded with a left or right button press to targets (counterbalanced across blocks). Target detection was poorer in patients than controls and for tones than syllables. Reference-free current source densities (CSDs; spherical spline Laplacian) derived from ERP waveforms were simplified and measured using temporal, covariance-based PCA followed by unrestricted Varimax rotation. Target-related N2 sinks and mid-parietal P3 sources were represented by CSD factors peaking at 245 and 440 ms. The P3 source topography included a secondary, left-lateralized temporal lobe maximum for both targets and nontargets. However, a subsequent hemispheric spatiotemporal PCA disentangled temporal lobe N1 and P3 sources as distinct factors. P3 sources were reduced in patients compared with controls, even after using performance as a covariate. Results are consistent with prior reports of P3 reduction in depression and implicate distinct parietal and temporal generators of P3 when using a dichotic oddball paradigm.
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PMID:Hemispatial PCA dissociates temporal from parietal ERP generator patterns: CSD components in healthy adults and depressed patients during a dichotic oddball task. 1796 12

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.
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PMID:The ERP PCA Toolkit: an open source program for advanced statistical analysis of event-related potential data. 2003 87

Dimensionality reduction and feature selection is an important aspect of electroencephalography based event related potential detection systems such as brain computer interfaces. In our study, a predefined sequence of letters was presented to subjects in a Rapid Serial Visual Presentation (RSVP) paradigm. EEG data were collected and analyzed offline. A linear discriminant analysis (LDA) classifier was designed as the ERP (Event Related Potential) detector for its simplicity. Different dimensionality reduction and feature selection methods were applied and compared in a greedy wrapper framework. Experimental results showed that PCA with the first 10 principal components for each channel performed best and could be used in both online and offline systems.
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PMID:A comparison of different dimensionality reduction and feature selection methods for single trial ERP detection. 2109 71

The current study investigated the association between neural engagement with task-irrelevant images and subsequent interference with target processing using the Emotional Interrupt paradigm [Mitchell, D., Richell, R., Leonard, A., & Blair, R. Emotion at the expense of cognition: Psychopathic individuals outperform controls on an operant response task. Journal of Abnormal Psychology, 115, 559, 2006]. Consistent with previous studies, PCA-derived factors corresponding to the early posterior negativity, P300, and late positive potential (LPP) were enhanced for emotional (i.e., both unpleasant and pleasant) compared with neutral distracters, and the P300 elicited by targets was smaller following emotional compared with neutral pictures. In addition, RTs were increased to targets that followed emotional pictures. Within-subject analyses demonstrated that slow trials were characterized by a smaller P300 and were preceded by pictures with a larger LPP. Additionally, between-subject analyses indicate that individuals with a larger LPP also demonstrated slower RTs to targets and reduced target-elicited P300s. All results were specific to the LPP and were not observed for either the early posterior negativity or the P300 elicited by task-irrelevant pictures. By relating the LPP to subsequent behavioral and ERP interference in both within- and between-subject analyses, the current study provides direct support for the notion that LPP indexes attentional engagement with visual stimuli that is uniquely associated with subsequent interference in terms of both RT slowing and P300 reduction to targets.
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PMID:The late positive potential predicts subsequent interference with target processing. 2126 68

According to the reinforcement learning account of the error-related negativity (ERN), the ERN is a manifestation of a signal generated in ACC as a consequence of a phasic decrease in the activity of the mesencephalic dopamine system occurring when the monitoring system evaluates events as worse than expected. This signal is also hypothesized to be used to modify behavior to ascertain that future events will have better outcomes. It is therefore expected that this signal be correlated with learning outcomes. We report a study designed to examine the extent to which the ERN is related to learning outcomes within a paired-associates learning task. The feedback-related negativity (FRN) elicited by stimuli that indicated to the participants whether their response was correct or not was examined both according the degree to which the associates were learned in the session and according to whether participants recalled the associations on the next day. The results of the spatio-temporal PCA indicate that, whereas the process giving rise to the negative feedback elicited a FRN whose amplitude was not correlated with long-term learning outcomes, positive feedback was associated with a FRN-like activity, which was correlated with the learning outcomes. Another ERP component that follows the FRN temporally and shares its spatial distribution was found associated with long-term learning outcomes. Our findings shed light on the functional significance of the feedback-related ERP components and are discussed within the framework of the reinforcement learning ERN hypothesis.
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PMID:The good, the bad, or the useful? The examination of the relationship between the feedback-related negativity (FRN) and long-term learning outcomes. 2348 47


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