Biomedical subjects

P J Corr

Publications and source records attributed to P J Corr.

8 recordsLinked to original sources

PubMed2000

Individual differences in mood reactions to d-amphetamine: a test of three personality factors.

Individual differences in self-reported mood following either 5 mg or 10 mg d-amphetamine challenge were examined in order to test the modifying role of three factors of personality, viz., the Eysencks' psychoticism, Cloninger's novelty seeking, and Depue and Collins' extraversion. In a double-blind study, mood measures (energetic arousal, tense arousal, and hedonic tone) were taken immediately following a single-dose of d-amphetamine and then again after 90 min. The results showed significant psychoticism x d-amphetamine interactions for both drug doses: d-amphetamine increased energetic arousal and hedonic tone, and reduced tense arousal, only in low psychoticism individuals; in high psychoticism individuals, it led to lowered energetic arousal and hedonic tone, and increased tense arousal. Neither novelty seeking nor extraversion modified the effects of d-amphetamine. These data suggest a link between psychoticism and dopaminergic functioning, although they do not rule out the involvement of other transmitter systems (e.g. noradrenergic). In common with other studies, such findings point to the important role that well-established factors of personality play in accounting for individual differences in reactions to psychoactive drugs. It is concluded that the routine inclusion of personality measures in future psychopharmacological studies may help to refine the characterization of drug effects.

Adult↗

PubMed1999

Effects of d-amphetamine and haloperidol on latent inhibition in healthy male volunteers.

Latent inhibition (LI) refers to a retardation of learning about the consequences of a stimulus when that stimulus has been passively presented a number of times without reinforcement. Acute positive-symptom schizophrenics, normal volunteers who score high on questionnaire measures of schizotypy and non-patients or animals treated with dopamine agonists show reduced LI. Neuroleptic drugs, such as haloperidol, administered at low doses, potentiate LI and effectively reverse disruption of LI induced by dopamine agonists in animals. However, a high dose of haloperidol, administered on its own, has been found to reduce LI. We examined the effects on LI of acute oral administration of an indirect dopamine-agonist, d-amphetamine (5 mg), and a nonselective dopamine receptor antagonist, haloperidol (5 mg), in normal male volunteers, using an associative learning task. Replicating previous reports, we found that d-amphetamine reduced LI; haloperidol also reduced LI, but only in subjects who scored low on the Psychoticism scale of the Eysenck Personality Questionnaire. In a subsequent study, no effect was found of 2 mg oral haloperidol administration on LI. The effect of 5 mg haloperidol on LI is interpreted as similar to that observed with a high dose of haloperidol in rats.

Adrenergic Agents↗

PubMed1997

Effects of acute administration of d-amphetamine and haloperidol on procedural learning in man.

The effects of an indirect dopamine-agonist, d-amphetamine, and a non-selective dopamine receptor antagonist, haloperidol, were investigated in normal male volunteers using a between-subjects double-blind design in a procedural learning task, thought mainly to involve unconscious/automatic learning. The results showed: (1) d-amphetamine facilitated response speed, whereas haloperidol inhibited it, in comparison to placebo; (2) the linear increase in procedural learning corresponded with pharmacological manipulation of degree of dopaminergic activity, i.e. subjects given haloperidol showed the least, and subjects given d-amphetamine the greatest, procedural learning. The implications of these findings are discussed in relation to investigation of abnormalities of procedural learning processes in schizophrenia.

Adolescent↗

PubMed1997

Personality, punishment, and procedural learning: a test of J.A. Gray's anxiety theory.

Effects of punishment and personality on a phylogenetically old form of knowledge acquisition, procedural learning, were studied to test J. A. Gray's 1970, 1987, 1991) theory of anxiety. Broad measures of personality (extraversion, E.; neuroticism, N; and psychoticism, P) and specific measures of trait anxiety (Anx) and impulsivity (Imp) were taken. Punishment led to response invigoration, reducing reaction time latency, but this was not related to personality. A negative correlation of P and learning was observed in both punishment and control conditions. In support of Gray's theory, high Anx improved learning under punishment (and impaired learning under control), and low Anx improved learning under control (and impaired learning under punishment). These data are contrasted with H.J. Eysenck's (1967) arousal theory of personality. Results point to a new behavioral tool with which researchers can explore further the interaction of reinforcement, arousal, and personality.

Adult↗

PubMed1997

Hindi translation of the Gray-Wilson Personality Questionnaire: a cross-cultural replication of sex differences.

The Gray-Wilson Personality Questionnaire (GWPQ) was translated into Hindi and administered to 246 male and 191 female university students. It measures six animal-learning paradigms corresponding to Gray's (1987) three-emotion systems model of personality. Sex differences previously reported from the United Kingdom and Japan were replicated: Women scored significantly higher on the Active Avoidance and Flight subscales, men on the Approach subscale. In the Indian sample, women scored higher than men on the Extinction subscale; this difference, although in the same direction, was not significant in the United Kingdom and Japan. In India, as in Japan and the United Kingdom, women were relatively punishment sensitive, and men were relatively reward sensitive. Consistent with Gray's model, scores on Fight and Flight subscales were positively correlated, as were Passive Avoidance and Extinction subscale scores; however, contrary to the model were the negative correlation between subscale scores for Approach and Active Avoidance and the positive correlation between subscale scores for Approach and Passive Avoidance, also observed previously in the United Kingdom and Japan.

Adolescent↗

PubMed1996

Effect of clonidine on the human acoustic startle reflex.

The present study investigated in healthy human volunteers whether clonidine reduced the amplitude of the acoustic startle reflex and whether this effect, if found, was due to an accelerated rate of habituation. Subjects were presented with startle-eliciting noise-bursts after intravenous (iv) infusion of clonidine (1.5 microgram/kg) and saline on separate days. Clonidine significantly reduced the amplitude of the acoustic startle reflex (as indexed by the eyeblink component) relative to the saline treated condition. This effect was neither due to an accelerated rate of habituation of the startle reflex nor to the sedative effect of clonidine. These findings complement an earlier report (Morgan et al. 1993) that yohimbine augments the amplitude of the startle reflex in man. Taken together, the two reports indicate a new model for the clinical investigation of central alpha2 adrenoceptor function in humans.

Acoustic Stimulation↗

PubMed1996

Effects of nicotine and amphetamine on latent inhibition in human subjects.

Latent inhibition (LI) is a phenomenon in which repeated non-reinforced exposure to a stimulus retards subsequent conditioning to that stimulus; it reflects a process whereby irrelevant stimuli become ignored, and has been the subject of study concerning attentional abnormalities in schizophrenia. Low doses of the indirect dopamine (DA) agonists, amphetamine and nicotine, disrupt LI in the rat. These drugs are believed to disrupt LI via DA release in the nucleus accumbens; LI in amphetamine- and nicotine-treated rats is reinstated by administration of the DA antagonist haloperidol. In human subjects, low doses of amphetamine abolish LI, and more recently haloperidol has been shown to potentiate LI. The present study investigated the effects of nicotine on LI in human subjects, and also attempted to replicate the abolition of LI by amphetamine. Nicotine failed to affect LI when administered either subcutaneously or by cigarette smoking. LI was, however, abolished in a group of subjects given 5 mg amphetamine 90 min before testing. Supplementary analyses of the data pooled from all three experiments showed that, in contrast to an earlier report, LI was no weaker in smokers than in nonsmokers.

Adult↗

PubMed1996

Menstrual cycle, arousal-induction, and intelligence test performance.

Regularly menstruating students (aged 19 to 25 yr.) were tested in the morning under high and low arousal-induction conditions (with time-pressure instructions vs without time-pressure instructions) during either midcycle (n = 16 or menstruation phase (n = 16) to study the interactive effects of menstrual phases and time-pressure stress-induced arousal on intelligence test scores on Raven's Standard Progressive Matrices and Hundal's General Mental Ability Test. A crossover interactive effect of menstrual phase and stress-induced arousal was found on performance of the Hundal test, suggesting that performance of subjects who were tested during the midcycle phase (putatively High Basal Arousal) was impaired under the time-pressure instructions condition (High-induced Arousal) as compared to performance under the without time-pressure instructions condition (Low-induced Arousal), with the reverse pattern of effects being true for subjects who were tested during the menstruation phase. Scores on Hundal's test conform to the Yerkes-Dodson (1908) law which relates arousal to task performance and suggests that the menstrual cycle and performance on the intelligence test was arousal-based. No effects, however, were observed for Raven's Matrices, raising the possibility that task characteristics may mediate the relationship between arousal and performance.

Adult↗