Event-related Brain Potentials Effects Research Articles

Endogenous Covert Spatial Orienting in Audition Cost-Benefit Analyses of Reaction Times and Event related Potentials

The present study examines mechanisms of endogenous covert spatial orienting in audition as revealed by event-related brain potentials (ERPs) and reaction times (RTs). In one experimental condition, subjects were instructed to respond to any target tone irrespective of whether it was presented in a valid (spatially predictive cue), neutral (uninformative cue), or invalid (misleading cue) trial. In another experimental condition, only target tones presented at a cued position required a response—that is, subjects could completely ignore tones presented at the uncued ear. Cue validity had an effect on RT, which consisted in benefits for valid trials and in costs for invalid trials relative to the RTs in neutral trials. There were also distinct ERP effects of cue validity in the 100–300 msec time range. These ERP effects were enlarged in the condition in which uncued tones could be ignored. The effects of cue validity on RTs and ERPs demonstrated covert orienting in audition both for stimuli requiring an overt response and also for stimuli that did not require a behavioural response. It is argued that this attentional selection is located at intermediate stages of information processing, rather than at peripheral stages such as basic sensory-specific processing or response selection.

An event-related potential study of retroactive interference in memory.

Neural activity associated with overcoming retroactive interference in episodic memory was investigated with event-related brain potentials (ERPs). ERPs were recorded during a combined recognition/associative recall memory test in which subjects were required to identify previous studied words and recall their study associates. A retroactive interference condition (A-B, A-C, A-?) was compared with two control conditions A-B, C-D, A-? and A-B, A-B, A-?). No ERP effect specific to the interference condition was identified. ERPs to all three classes of old word differed however from those to new words. These differences involved two effects, one with a left parietal maximum that has been described before, and a left frontal effect of earlier onset which has not been reported previously. This latter effect may indicate a role for the left prefrontal cortex in associative retrieval.

Modulation of Event-Related Potentials by Semantic Priming: Effects of Color-Cued Selective Attention

The processing nature of N400, an event-related brain potential (ERP) component associated with semantic processing, was investigated in a paradigm combining a semantic priming lexical decision task and color-cued selective attention. Semantic priming effects on ERPs and reaction time (RT) were examined when targets and preceding semantically related primes were either both attended or both unattended, and when only either the prime or target was the focus of attention. Priming effects were determined by comparing semantically primed target ERPs (and RTs when appropriate) to their prime (in those conditions where the prime and target had the same attentional status) and/or to an unprimed control target matched to the attentional status of the primed target. Control stimuli were examined for ERP effects of color-cued selective attention unconfounded by priming factors. Experiment 1 required overt responses to words and nonwords in a binary choice task, while Experiment 2 required response only to nonwords. RTs in Experiment 1 indicated facilitatory priming effects to all semantically primed attended targets. In Experiments 1 and 2 ERPs to primes and controls were consistently more negative than the primed target trace in the N400 latency range in conditions with attended primes, suggesting priming effects on N400 are contingent on attentional processing of the prime. Removal of the attention manipulation (Experiment 3) resulted in an N400 component with a well-defined peak not evident in the first two experiments, indicating modulation of N400 by overlapping effects of attention.

Temporal structure of syntactic parsing: early and late event-related brain potential effects.

Event-related brain potentials (ERPs) were recorded from participants listening to or reading sentences that were correct, contained a violation of the required syntactic category, or contained a syntactic-category ambiguity. When sentences were presented auditorily (Experiment 1), there was an early left anterior negativity for syntactic-category violations, but not for syntactic-category ambiguities. Both anomaly types elicited a late centroparietally distributed positivity. When sentences were presented visually word by word (Experiment 2), again an early left anterior negativity was found only for syntactic-category violations, and both types of anomalies elicited a late positivity. The combined data are taken to be consistent with a 2-stage model of parsing, including a 1st stage, during which an initial phrase structure is built and a 2nd stage, during which thematic role assignment and, if necessary, reanalysis takes place. Disruptions to the 1st stage of syntactic parsing appear to be correlated with an early left anterior negativity, whereas disruptions to the 2nd stage might be correlated with a late posterior distributed positivity.

Temporal structure of syntactic parsing: Early and late event-related brain potential effects.

Temporal structure of syntactic parsing: Early and late event-related brain potential effects.

Metamemory, distinctiveness, and event-related potentials in recognition memory for faces.

A neglected topic in metamemory research is the ability of subjects to predict their own recognition performance for faces. We investigated whether subjects can make such judgments of learning (JOL) for unfamiliar faces and whether JOLs relate to facial distinctiveness, a powerful determinant of face recognition. One group of subjects made JOLs, and a second group rated the same faces for distinctiveness; subsequently, both groups tried to recognize these faces among new faces. There was significant prospective metamemory for faces that appeared to be based on facial distinctiveness. Both prospective metamemory and distinctiveness ratings related to long-lasting effects in event-related brain potentials (ERPs), closely resembling an ERP component that predicted face recognition. Therefore, the brain processes underlying JOLs, distinctiveness, and recognition memory for faces appear to be intimately related.

Neurophysiological Manifestations of Phonological Processing: Latency Variation of a Negative ERP Component Timelocked to Phonological Mismatch

Abstract Two experiments examined phonological priming effects on reaction times, error rates, and event-related brain potential (ERP) measures in an auditory lexical decision task. In Experiment 1 related prime-target pairs rhymed, and in Experiment 2 they alliterated (i.e., shared the consonantal onset and vowel). Event-related potentials were recorded in a delayed response task. Reaction times and error rates were obtained both for the delayed and an immediate response task. The behavioral data of Experiment 1 provided evidence for phonological facilitation of word, but not of nonword decisions. The brain potentials were more negative to unrelated than to rhyming word-word pairs between 450 and 700 rnsec after target onset. This negative enhancement was not present for word-nonword pairs. Thus, the ERP results match the behavioral data. The behavioral data of Experiment 2 provided no evidence for phonological Facilitation. However, between 250 and 450 msec after target onset, i.e., considerably earlier than in Experiment 1, brain potentials were more negative for unrelated than for alliterating Word-word and word-nonword pairs. It is argued that the ERP effects in the two experiments could be modulations of the same underlying component, possibly the N400. The difference in the timing of the effects is likely to be due to the fact that the shared segments in related stimulus pairs appeared in different word positions in the two experiments.

Effects of isolated and combined exposures to whole-body vibration and noise on auditory-event related brain potentials and psychophysical assessment.

Auditory event-related brain potentials (ERP) in response to two different tone stimuli (1.1 kHz or 1 kHz, 80 dB, 50 ms; given by headphones at a regular interstimulus interval of 5 s with a probability distribution of 70:30) were recorded from 12 healthy male subjects (Ss) during four different conditions with two repetitions: A-60 dBA white noise (wN), no whole-body vibration (WBV); B-60 dBA wN plus sinusoidal WBV in the az-direction with a frequency of 2.01 Hz and acceleration of 2 m.s-2 root mean square; C-80 dBA wN, no WBV; D-80 dBA wN plus WBV. Each condition consisted of two runs of about 11 min interrupted by a break of 4 min. During the break with continuing exposure, but without auditory stimuli, Ss judged the difficulty of the tone-detection task and intensity of noise by means of cross-modality matching (CMM). Vibration-synchronous activity in the electrocardiogram was eliminated by a subtraction-technique. Noise caused an attenuation of the N1 and P2 amplitudes and prolongation of P3 latencies. The WBV did not cause systematic ERP effects. Condition B was associated with higher N1 and smaller P3 amplitudes. The factor "condition" had a significant effect on the peak latencies of P3 to target stimuli and the task difficulty judged by CMM. Both effects exhibited significant linear increases in the sequence of conditions A, B, C, D. For the evaluation of exposure conditions at work, it can be suggested that noise has a strong systematic effect which can be enhanced by WBV.(ABSTRACT TRUNCATED AT 250 WORDS)

Short-term memory storage and retention: an event-related brain potential study

This experiment was concerned with event-related brain potential (ERP) activity related to short-term storage and retention of information in working memory. Our approach was to record the ERPs elicited by a stimulus that had to be memorized while varying the number of items (1, 3 or 6) in the task stimulus. In order to distinguish between ERP effects associated with perceptual complexity and retention of information, there was a second condition in which subjects were required to search the task stimulus for a match with a previously presented item. Thus, in the search condition subjects only had to remember one item (match or mismatch). ERP activity was recorded for 2450 msec after task stimulus offset. Two long-duration components varied as a function of task and memory load: a posterior positive wave and a frontal negative wave. Posterior positive wave amplitude was directly related to information load in the memory task but was negligible in the search task. Following the posterior positive wave was a frontal negative wave which occurred at the highest load level in the memory task but was totally absent in the search task. A P3b was elicited in both tasks. P3b was sensitive to information acquisition processes, but it did not distinguish between memory retention and visual search processes. While P3b amplitude did not vary with task or load, its latency increased with load in both tasks.

Event-related brain potentials to semantically inappropriate and surprisingly large words

Event-related brain potentials (ERPs) were recorded from young adult subjects as they silently read 160 different seven-word sentences, presented one work at a time. The sentences either ended normally or were completed by unexpected words that were either semantically inappropriate, physically deviant or both. These two types of deviations were associated with distinctly different ERP components - a late negative wave (N400) for semantic deviations and a late positive complex for physical deviations. A deviation along either one or these dimensions (semantic or physical) did not appear to alter the ERP effect of a concurrent deviation along the other. In addition, it was found that the ERPs elicited by the words during the reading condition were characterized by a left-greater-than-right asymmetry in a slow, positive component. This asymmetrical scalp distribution was most pronounced for right-handed subjects having not left-handers in their immediate family.