John Polich

Updating P300: An Integrative Theory of P3a and P3b

The empirical and theoretical development of the P300 event-related brain potential (ERP) is reviewed by considering factors that contribute to its amplitude, latency, and general characteristics. The neuropsychological origins of the P3a and P3b subcomponents are detailed, and how target/standard discrimination difficulty modulates scalp topography is discussed. The neural loci of P3a and P3b generation are outlined, and a cognitive model is proffered: P3a originates from stimulus-driven frontal attention mechanisms during task processing, whereas P3b originates from temporal-parietal activity associated with attention and appears related to subsequent memory processing. Neurotransmitter actions associating P3a to frontal/dopaminergic and P3b to parietal/norepinephrine pathways are highlighted. Neuroinhibition is suggested as an overarching theoretical mechanism for P300, which is elicited when stimulus detection engages memory operations.

Cognitive and biological determinants of P300: An integrative review

The P300 event-related brain potential (ERP) is thought to reflect neuroelectric activity related to cognitive processes such as attention allocation and activation of immediate memory. However, recent studies have provided evidence that the P300 also is influenced by biological processes such as fluctuations in the arousal state of subjects. The effects of natural (circadian, ultradian, seasonal, menstrual) and environmentally induced (exercise, fatigue, drugs) state variables on the P300 are reviewed. The findings suggest that these factors contribute to P300 measures and are discussed in terms of their theoretical and applied implications.

Affective picture processing: An integrative review of ERP findings

The review summarizes and integrates findings from 40 years of event-related potential (ERP) studies using pictures that differ in valence (unpleasant-to-pleasant) and arousal (low-to-high) and that are used to elicit emotional processing. Affective stimulus factors primarily modulate ERP component amplitude, with little change in peak latency observed. Arousal effects are consistently obtained, and generally occur at longer latencies. Valence effects are inconsistently reported at several latency ranges, including very early components. Some affective ERP modulations vary with recording methodology, stimulus factors, as well as task-relevance and emotional state. Affective ERPs have been linked theoretically to attention orientation for unpleasant pictures at earlier components (<300 ms). Enhanced stimulus processing has been associated with memory encoding for arousing pictures of assumed intrinsic motivational relevance, with task-induced differences contributing to emotional reactivity at later components (>300 ms). Theoretical issues, stimulus factors, task demands, and individual differences are discussed.

Event-related potentials in clinical research: Guidelines for eliciting, recording, and quantifying mismatch negativity, P300, and N400

This paper describes recommended methods for the use of event-related brain potentials (ERPs) in clinical research and reviews applications to a variety of psychiatric and neurological disorders. Techniques are presented for eliciting, recording, and quantifying three major cognitive components with confirmed clinical utility: mismatch negativity (MMN), P300, and N400. Also highlighted are applications of each of the components as methods of investigating central nervous system pathology. The guidelines are intended to assist investigators who use ERPs in clinical research, in an effort to provide clear and concise recommendations and thereby to standardize methodology and facilitate comparability of data across laboratories.

Binge drinking in young adults: Data, definitions, and determinants

Binge drinking is an increasingly important topic in alcohol research, but the field lacks empirical cohesion and definitional precision. The present review summarizes findings and viewpoints from the scientific binge-drinking literature. Epidemiological studies quantify the seriousness of alcohol-related problems arising from binge drinking, with a growing incidence reported in college-age men over the last 2 years. Experimental studies have found neurocognitive deficits for frontal lobe processing and working memory operations in binge-drinking compared with nonbinge alcohol drinkers. The findings are organized with the goals of providing a useful binge-drinking definition in the context of the empirical results. Theoretical implications are discussed on how binge drinking may alter neurophysiological and neurocognitive function.

P3a and P3b from typical auditory and visual stimuli

OBJECTIVE Target/standard discrimination difficulty was manipulated systematically to assess how this variable affects target and nontarget P300 scalp distributions for both auditory and visual stimuli. DESIGN AND METHODS A 3-stimulus paradigm (target, standard, nontarget) was employed in which subjects (n = 16) responded only to an infrequently occurring target stimulus. The perceptual discrimination difficulty between the target and more frequently occurring standard stimuli was varied as Easy or Difficult in different conditions, while holding the nontarget stimulus properties constant. RESULTS When target/standard discrimination was Easy, P300 amplitude was larger for the target than the nontarget across all electrode sites, and both demonstrated parietal maximums. In contrast, when target/standard discrimination was Difficult, target amplitude (P3b) was larger parietally and occurred later than nontarget components, whereas nontarget amplitude (P3a) was larger and earlier than the target P300 over the frontal electrode sites. Similar outcomes across task conditions were obtained for both auditory and visual stimuli. CONCLUSIONS The findings suggest that target/standard discrimination difficulty, rather than stimulus novelty, determines P3a generation for both auditory and visual stimulus modalities.

Meta-analysis of P300 amplitude from males at risk for alcoholism.

The P3(00) event-related brain potential (ERP) is used to study the development of alcoholism by comparing males who have a positive family history of alcoholism with control Ss who have no such familial history. Meta-analysis indicated that overall, smaller P3 amplitudes were obtained from males with family histories of alcoholism compared to controls. Moderator analysis indicated that paradigms using difficult visual tasks yielded the most reliable effects. Furthermore, no differences in outcomes were obtained among studies that recruited positive family history Ss exclusively from among individuals whose father had received treatment for alcoholism as compared with other studies. These findings are discussed in the context of using ERPs as an evaluative tool in the study of psychopathology.

P300 as a clinical assay: rationale, evaluation, and findings.

Use of the P300 event-related brain potential (ERP) as a clinical assay is reviewed and assessed by comparing its distribution qualities with normative biomedical testing data from published studies. The coefficient of variation statistic was calculated for P300 data and a variety of clinical testing data. P300 amplitude and latency variability was found to be highly comparable and sometimes superior to routinely employed biomedical assays. These results are discussed in terms of how to control inter-group ERP variability and the application of normative P300 data in clinical settings.

P300 latency reflects the degree of cognitive decline in dementing illness.

An auditory discrimination paradigm was employed to elicit the P3 component of the event-related brain potential (ERP) from 39 demented patients (mean age = 71 years). Component latency was longer in patients who were diagnosed as having primary degenerative dementia and other cognitive impairment disorders compared to age-matched controls. Neurologist ratings of cognitive impairment were significantly correlated with P3 latency values, although no differences in mean latency were obtained between the various categories of dementia. ERP measurement techniques and the interpretation of P3 latency as in index of dementing illness are discussed.

Task difficulty, probability, and inter-stimulus interval as determinants of P300 from auditory stimuli

The P300 event-related potential was elicited with auditory stimuli in 4 experiments which manipulated combinations of stimulus target probability (10% vs. 30%), task difficulty (easy vs. hard), and inter-stimulus interval (5 sec vs. 2 sec). P300 amplitude was smaller and peak latency longer for the more difficult relative to the easier tasks across experiments. Increases in stimulus target probability generally diminished P300 amplitude and shortened peak latency more for the easy relative to difficult task conditions. Increasing the number of non-target stimulus tones decreased P300 amplitude reliably, but increased latency only slightly. Task difficulty did not interact with variations in inter-stimulus interval which produced generally weak effects for both amplitude and latency. These findings suggest that P300 amplitude and latency obtained from auditory discrimination paradigms reflect processing difficulty independently of stimulus target probability unless differences in task requirements affect stimulus encoding.