Individual differences in components of slow cortical potentials: implications for models of information processing

Electrophysiological responses to affective stimuli in Mexican Americans: Relationship to alcohol dependence and personality traits

The relationship between the P450 component elicited by affective stimuli and: a personal history of alcohol dependence, antisocial personality disorder/conduct disorder (ASPD/CD) or affective anxiety disorders (ANYAXAF) was examined in Mexican Americans, a group with high rates of heavy drinking. Data from two hundred and twenty two young adults between the ages of 18 and 30 were used in the analyses. ERPs were collected using a task that required discrimination between faces with neutral, sad and happy facial expressions. DSM-IIIR diagnoses were obtained using a structured interview and personality traits were indexed using the Maudsley personality inventory. Men had significantly diminished P450 responses, when compared to women which were further reduced in men with ASPD/CD; whereas, a significant increase in P450 amplitudes was seen in those participants with ANYAXAF. P450 amplitudes were also significantly increased in men with high extraversion scores and in women with high neuroticism scores. No significant associations were seen between the P450 amplitude and the diagnosis of alcohol dependence. These data suggest that interpretations of P450 responses in Mexican Americans need to take into account the interactions between gender, the affective valence of the eliciting stimuli, as well as psychiatric status.

Habituation of P3a and P3b brain potentials in men engaged in extreme sports

Do person characteristics determine when novel, attention-grabbing stimuli loose their novelty? The aim of the present study was to investigate habituation of the visual event-related potentials (ERP) P3a and P3b in men that (1) were engaged in extreme sports, (2) had extremely high scores on the Impulsivity Sensation Seeking scale of the Zuckerman-Kuhlman Personality Questionnaire (ZKPQ), yet were not engaged in extreme sports, or (3) had extremely low scores on ZKPQ. The results showed that P3a habituated significantly more in extreme sporters than in the other groups. The same was not found in comparison of the high and the low ZKPQ scorers. There were not differences between the groups in overall amplitude. It is concluded that ERP habituation may be more relevant than mere amplitude to the sensation seeking trait in extreme sporters, and that they differ from others in ERPs related to automatic alerting-related processes, not controlled cognitive processing.

The acute effect of cigarette smoking on pattern visual evoked potentials

Reports of tobacco-induced electrocortical activation and decrements in ocular blood flow in the acute phase indicated that this effect is mediated via nicotine's action or neuronal systems. In this study, pattern visual evoked potentials were investigated in a group of male smokers (22 right eyes of 22 subjects) in separate real smoking and sham smoking sessions. On each session, pattern visual evoked potentials were recorded before smoking, immediately after smoking, and five minutes after smoking. Latency and amplitude values for P100 peaks were assessed and analyzed in each smoking condition for both real smoking and sham smoking sessions. Real smoking significantly decreased P100 latency values (p value related to difference between pre-smoking and immediately after smoking conditions is 0.009) and increased P100 amplitude values (p value related to difference between pre-smoking and fifth minute after smoking is 0.039). Statistically no significant difference was observed in sham smoking sessions. Our results are consistent with smoking-induced stimulant effects on pattern visual evoked potentials.

P300 event-related brain potential and personality in depression

P300 is an event-related brain potential (ERP) particularly interesting to the study of cognitive processes in normal subjects and in psychopathology. P300 has been applied in depression with controversial results. A major source for these controversial results could result from the diversity of depressed patients included in the different studies. Supporting this assumption, impulsivity, blunted affect, suicidal behavior and psychotic features significantly influence P300 amplitude. However, no data are available on the possible influences of the personality of depressed patients on P300. Since personality is related to P300 in normal subjects, the aim of the present study is to investigate the relationship between ERPs (P200, N200, and P300) and the Temperament and Character Inventory (TCI) in 54 depressed patients. The main results of the study concern the absence of major correlations between personality dimensions as assessed by the TCI and ERP parameters among depressed patients. Only weak partial positive correlations relate N200 latency with harm avoidance, and P300 amplitude (Pz) with the self-directedness dimension. N200 amplitude is also negatively correlated to persistence. However, the preliminary nature of the presented results with respect to the weak statistical significance should be underlined.

P300 and personality: an investigation with the Cloninger's model

The relationships between P300 and personality have been explored mainly in reference to the model of personality described by Eysenck because of its biological bases. Recently, Cloninger and his colleagues have proposed a model of personality based on four temperaments and three characters. The Temperament and Character Inventory (TCI) is a 226-item self-questionnaire developed to assess these seven dimensions of personality. In the present study, the relationships between these dimensions of personality and P300 have been investigated in 43 normal subjects. The results show that P300 amplitude is positively correlated with the novelty seeking dimension and negatively correlated with the harm avoidance dimension. In contrast, the other dimensions of the TCI were not related to P300 amplitude. Moreover, P300 latency and reaction time were not associated with the TCI dimensions of personality. This study confirms that personality is related to P300.

Time effects on event-related brain potentials and vigilance performance

A review of the literature showed that in vigilance or oddball tasks, changes over time in event-related potentials (ERPs) and performance measures often seem to be unrelated, but a number of studies had some shortcomings. In the present study a visual vigilance experiment was carried out, in which single-trial ERPs and performance data of 40 males were obtained. A relationship between time trends in behavioral and ERP measures was found: an early P3 amplitude and response latency (RT) showed an inversely varying relation over time. Analysis of covariance showed that the two linear trends tap the same aspect of processing: both trends became insignificant when adjusted for common variance. A negative correlation between mean values of P3 amplitude and RT rather than for change scores has been observed in previous studies, but has been ignored in the literature. However, correlations with RT have also been reported for other ERP deflections. Although there were several correlations between mean scores, most time-induced changes in ERP parameters appeared to be unrelated to worsening performance, for which several explanations are advanced. The ERP results do not support the hypothesis that a decrement in performance is caused by increasing difficulty discriminating targets from nontargets. A gradual decline in effort or resources allocated to the task might be an alternative explanation of performance deterioration. However, an effort-hypothesis cannot easily be tested. Effort is often invoked post hoc, and has previously been associated with many ERP components. The relationship between ERPs and the signal detection measures "sensitivity" d' and "response bias" beta is discussed.

P300, probability, and introverted/extroverted personality types

Extreme introverted and extroverted subject groups (n = 24 each) containing equal numbers of male and females were assessed with the P300 (P3) component of the event-related potential (ERP). A two-tone auditory discrimination task in which the probability of the target stimulus varied systematically in different conditions (.20, .40, .60, .80) was used to elicit the ERPs. The P3 amplitude demonstrated a significant interaction between personality type, probability, and subject gender and was generally smaller for introverts than for extroverts. Female subjects tended to have larger overall P3 components than male subjects. P3 latency was not affected by the personality variable. The results support previous findings for ERP differences between introverts and extroverts and suggest that personality type differentially influences target stimulus probability effects. The findings are discussed in terms of individual differences in cortical activity on P3 amplitude and personality measures.

ERP augmenting/reducing and sensation seeking: a critical review

Event-related potentials (ERPs) are generally considered capable of throwing light on the biological basis of personality traits. In particular, the ERP augmenting/reducing (A/R) phenomenon has been consistently associated with personality dimensions such as sensation seeking or impulsivity. However, doubts have been expressed regarding the validity of published evidence that individuals scoring high as sensation seekers are ERP augmenters. Reports of A/R-sensation seeking correlation in the opposite direction (in keeping with Petrie's hypotheses) threaten the construct validity of A/R, and lack of intermodal consistency throws serious doubts upon the existence of the central input-regulating mechanism once thought to be associated with sensation seeking. With the aim of clarification this article reviews the literature on the relationship between ERP A/R and sensation seeking, discusses the chief problems confronted by research in this area, and makes suggestions for future studies. It is concluded that experimental conditions of stimulus intensity and inter-stimulus interval may have played a part in the inconsistencies. The need to use a variety of measures of sensation seeking is stressed, and a number of other recommendations for research in this field are made.

P300 and introverted/extraverted personality types

The P300 component of the event-related potential elicited with a two-tone auditory discrimination task and two-trial block replication procedure was obtained from 16 introverted and 16 extraverted undergraduate students. P300 demonstrated no overall significant effects for either the personality variable or the block variable. However, P300 amplitude to the target stimuli declined significantly between Block 1 and Block 2 for the extraverted subjects, but did not change across trial blocks for the introverted group. Female subjects tended to have larger P3 amplitudes than male subjects, but this factor did not interact with either the personality variable or the trial block variable. The results suggest that P3 amplitude habituates more rapidly for extraverts than for introverts.

Can smoking increase attention in rapid information processing during noise? Electrocortical, physiological and behavioral effects

This study investigated the effects of smoking on subject-paced visual rapid information processing performance (RIP) under the influence of disturbing noise. The RIP task required the subjects to detect triads of even or odd digits within a pseudorandom sequence of single digits presented on a screen. Two groups of 12 female habitual smokers who were not allowed to smoke during the last 10 h preceding the test sessions underwent two test sessions each consisting of two RIP trials separated by a smoking period (habitual cigarette) for one group and by a relaxation period without smoking for the second group. Noise disturbance was presented during the second RIP trial of one of the two sessions only. Smoking increased RIP performance, but noise failed to show any measurable effect. EEG analyzed during RIP revealed the expected noise-induced decrease in alpha power. ERP analyses showed a smoking-induced decrease in the CNV-related negativity but no noise effects. The late positive wave (LP) increased after smoking, but to a lesser extent under the noise condition. The analyses of peripheral physiological measures revealed smoking- and noise-induced heart rate acceleration and cutaneous vasoconstriction. Plasma cortisol, prolactin and HGH were also increased after the noise session. The results indicate therefore that smoking increased RIP, whereas noise failed to affect mental performance, although it produced measurable vegetative stress effects.

Effects of cigarette smoking on resting EEG, visual evoked potentials and photic driving

The effects of smoking a cigarette (1.3 mg nicotine delivery) versus sham smoking were studied using EEG, visual evoked potentials (VEP), photic driving (PD) and heart rate (HR) in thirty young healthy male and female habitual cigarette smokers. Heart rate (HR) and exhaled carbon monoxide (CO) level were significantly increased by real as opposed to sham smoking. Real versus sham smoking significantly increased relative power in the beta bands, reduced alpha and theta activity to a small but significant extent, but had no effect on delta activity. Dominant EEG alpha frequency was significantly increased by real as opposed to sham smoking. Smoking produced no significant mean change in PD or VEP. However, correlational analysis indicated that variables such as basal CO level, residual butt filter nicotine, basal electrocortical response level and personality, predicted to varying degrees the magnitude and direction of the effect of smoking on VEP, PD and EEG.