Jan Kaiser

Psychometric intelligence and P3 of the event-related potentials studied with a 3-stimulus auditory oddball task

Relationship between psychometric intelligence measured with Ravens Advanced Progressive Matrices (RAPM) and event-related potentials (ERP) was examined using 3-stimulus oddball task. Subjects who had scored higher on RAPM exhibited larger amplitude of P3a component. Additional analysis using the Standardized Low Resolution Electromagnetic Tomography (sLORETA) revealed that this effect corresponds with stronger activity within the frontal cortex and the cingulate gyrus. High intelligence can also be linked with greater P3b response and stronger activity within the parietal cortex and the posterior cingulate gyrus. It may be concluded that the processes related to the initial stage of attention engagement as indexed by P3a, as well as the later stimulus evaluation and classification reflected in P3b, are more intense in subjects scoring higher on RAPM. The quality of mental abilities can therefore be related to differences of the activity in frontal and parietal brain regions.

The evoked cardiac response as a function of cognitive load differs between subjects separated on the main personality dimensions

Abstract We report research on different phasic evoked cardiac responses associated with differences in personality. Heart rate changes were examined in relation to the stable individual difference variables of psychoticism, neuroticism and extraversion. Subjects were divided into different pairs of subgroups on the basis of the measure of their personality dimension scores (above and below the group median). Each subject received 10 innocuous auditory stimuli with randomly varying interstimulus intervals. Stimuli were presented in one of two conditions. In the irrelevant condition there was no task, while in the relevant condition, subjects were required to count the number of stimuli presented. A main effect of condition was obtained in the evoked cardiac response. The initial heart rate deceleration was significantly larger in the irrelevant condition and a later acceleration was significantly larger in the relevant condition. High psychoticism subjects had smaller heart rate changes to the irrelevant stimuli and smaller differences between the relevant and irrelevant conditions than did low psychoticism subjects. High neuroticism subjects, compared with low neuroticism subjects, showed some enhanced cardiac responding to relevant stimuli, but there were no effects of differences in extraversion. The data are discussed in terms of the intensity of stimulus processing (both physical and cognitive) as a factor that may be related fundamentally to stable individual differences in personality.

Influence of diazepam and buspirone on human heart rate and the evoked cardiac response under varying cognitive load

The influence of two anxiolytics on basal heart rate and on the evoked cardiac response elicited by auditory stimuli, was studied in humans. Diazepam (Valium) (7.5 mg) and buspirone (Buspar) (7.5 mg), which differ in their psycho-pharmacological profiles, were used. Prestimulus vigilance and cognitive load were manipulated by instructions allowing the subjects to ignore the stimuli, or requiring them to count the tones. Drug effects were obtained in subjective alertness, basal heart rate level, and the evoked cardiac response. Diazepam reduced subjective alertness, while buspirone did not. Diazepam apparently increased heart rate levels relative to placebo, in contrast to buspirone, which produced an apparent decrease in heart rate. These drug-induced prestimulus heart rate level effects were associated with differential decelerations immediately following stimulus onset and appear to reflect differences in prestimulus vigilance. Opposite effects of the drugs were also observed in the second, acceleratory, component of the of the evoked cardiac response, and these were found to be independent of the prestimulus drug effects. Compared with placebo, buspirone appeared to enhance the acceleratory component in the count condition, while diazepam led to an apparent reduction of this component. Enhancement of this acceleration after buspirone may reflect an increase in cognitive effort directed to the performance of task-relevant behaviour, while the reduction of this component after diazepam can be regarded as a cognitive-motivational neutralisation of signal value. The differential effects of the two anxiolytics support the separation of the evoked cardiac response into different components and may also have implications for the clinical use of the drugs.

Evoked cardiac response correlates of cognitive processing and dimensions of personality: Eysenck’s concept of psychoticism revisited

Abstract The effects of agreeableness (A) and conscientiousness (C), as defined in the NEO-FFI scale, were examined in two components of the evoked cardiac response (ECR) elicited in response to innocuous auditory stimuli presented under IRRELEVANT and RELEVANT cognitive task conditions. The IRRELEVANT condition produced a simple cardiac deceleration, ECR1, while the RELEVANT condition produced a biphasic response dominated by a secondary cardiac acceleration. The difference in response, ECR2, is associated with differential cognitive processing. Our previous work noted differences as a function of Eysenck’s P scale, and this was used as a criterion to evaluate the A and C effects. Differences in levels of A were found to affect ECR1, while differences in C affected ECR2. The finding that the physiological correlates of A and C were different from each other is interpreted in terms of different mechanisms underlying these two big factors.

Covariation of EEG synchronization and emotional state as modified by anxiolytics

Summary: The relationships between subjective estimation of emotional state and synchronization patterns in cortical emotional systems were investigated. The emotional state varied between groups using diazepam, buspirone, and placebo. The University of Wales Institute of Science and Technology Mood Adjective Checklist was used for the assessment of emotional state in the drug condition, yielding three estimates of emotional state: Energetic Arousal, Tension Arousal, and Hedonic Tone. These measures were correlated with the Synchronization Likelihood index of the resting EEG. Increased affective valence and arousal were related to an increased level of synchronization between frontal and right temporoparietal emotional areas. Two identified centers of synchronization, localized in the temporal and centroparietal regions, appeared to be functionally distinct. Stable relationships between subjective emotional state measures and cortical EEG synchronization patterns were confirmed, especially for the valence and energetic arousal estimation. A higher synchronization is associated with increased emotional valence and arousal, and this can thus be seen as a neural correlate of emotional experiences.

The influence of context on the processing of emotional and neutral adjectives – An ERP study

The study investigated brain responses to emotional and neutral adjectives within contexts of varying emotional valence. Participants were randomly assigned to 3 context groups where they viewed random sequences of emotional and neutral adjectives intermixed with: emotional pictures (emotional context), neutral pictures (neutral context) and blank screens (zero context). Within the emotional context group the P3 potential was more pronounced in response to positive than either negative or neutral adjectives, and positive picture context impacted positive and negative adjectives differently. In the neutral context group the P2 and P3 potentials were greater in response to the positive adjectives as compared to the neutral ones. There was also a greater negativity of the N400 potential in response to the neutral adjectives. Within the zero context group only the N400 effect was visible. The seeming preference for positive words can be explained in terms of the specific positivity offset phenomenon.

The Influence of Emotionally Relevant Context on the Evoked Cardiac Response Triggered by an Irrelevant Stimulus

The effect of stimulus valence was examined in the evoked cardiac response (ECR) elicited by the exposition of neutral and negative slides as well as by an innocuous auditory stimulus presented on the affective foregrounds generated by the slides. The exposition of the aversive slide produced prolonged cardiac deceleration in comparison with the neutral slide. Similar prolonged deceleration accompanied exposition of the neutral auditory stimulus on the negative visual foreground in comparison with the neutral foreground. We interpret these results as an autonomic correlate of extended stimulus processing associated with the affective stimulus. The initial deceleration response, covering two or three slower heart beats, may be prolonged for several seconds before HR reaches the baseline level again. In such a case the evoked cardiac deceleration can be functionally divided into two parts: the reflexive bradycardia (ECR1) elicited by neutral stimuli and a late decelerative component (LDC). We can speculate that the latter is associated with an additional voluntary continuation of processing of the stimulus. This must involve some cognitive aspect different from the mental task performance which leads to the accelerative ECR2, and we suggest that processing of a stimulus with negative valence is involved in generating the LDC.

Influence of diazepam on prospective time estimation

24 students, after intake of diazepam or placebo, performed a psychomotor test of finger tapping as a prospective time-estimation task. The task was less overestimated by those who were under the influence of the drug than by the 12 subjects to whom the placebo was given.