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Biomedical subjects

J Kaiser

Publications and source records attributed to J Kaiser.

At least 163 records · Page 9Linked to original sources
PubMed1997

Hypnosis and event-related potential correlates of error processing in a stroop-type paradigm: a test of the frontal hypothesis.

A model of frontal inhibition in hypnosis was elucidated by examining with cortical evoked potentials error negativity and positivity in 23 low versus medium/high hypnotisables during a perceptual task which included trials with conflicting stimulus information. In susceptible subjects the number of correct responses was found to be smaller for trials with incongruent stimulus information with hypnosis when compared with baseline. While the early negative wave to incorrect responses tended to be higher in susceptible subjects, this wave was no longer followed by a late positivity, posited to reflect a failure to process further the error-related information. The results with hypnosis are interpreted as a failure of context updating without a global deficit in supervisory attention.

Adult↗
PubMed1996

Syndromes of schizotypy and timing of puberty.

Development regressive events such as pruning of synapses are implicated in schizophrenia with both over- and under-connectivity models proposed (Randall, Feinberg, Hoffman). Saugstad theorized that extremes of normal variation in age at puberty distinguish affective psychoses (early maturation) from schizophrenia (late maturation). In normal students we have found a three-factor structure of schizotypy traits (Active, Withdrawn and Unreality) which may parallel three-syndrome models of schizophrenia. Here, in a sample of 161 students we examined relations between schizotypy and extremes in the timing of puberty. Relations were almost exclusively syndromal. Unreality was associated with both extremes when compared with a group of normal maturers. Comparing early with late maturers, early maturing females were found to be Withdrawn, with features of social withdrawal and anhedonia. In contrast, Withdrawn males were late maturers, with features of social withdrawal and social anxiety. In females it was the Active syndrome (odd speech, impulsivity and activity) that was associated with late maturation. The results have relevance for both neurophysiological and social theories of personality, sex differences and psychopathology.

Adolescent↗
PubMed1996

The evoked cardiac response as a function of cognitive load in subjects differing on the individual difference variable of reaction time.

We report research on different phasic evoked cardiac responses associated with differences in cognitive activity. These were examined in relation to a stable individual difference variable, mean simple reaction time (RT). Individual means on RT were found to be sufficiently stable over a 10 month period to consider them as individual functional characteristics. Subjects were divided into two subgroups on the basis of the first measure of their individual mean RT (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 defined by instructions allowing them to ignore (irrelevant condition), or requiring them to count the stimuli (relevant condition). A main effect of instruction 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. Short-RT subjects had smaller heart rate changes to the irrelevant stimuli. The data are discussed in terms of the intensity of stimulus processing (both physical and cognitive) as a factor which may be related fundamentally to stable individual differences in RT.

Adult↗