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Biomedical subjects

J C Leslie

Publications and source records attributed to J C Leslie.

6 recordsLinked to original sources
PubMed1995

Interference with olfactory memory by visual and verbal tasks.

It has been claimed that olfactory memory is distinct from memory in other modalities. This study investigated the effectiveness of visual and verbal tasks in interfering with olfactory memory and included methodological changes from other recent studies. Subjects were allocated to one of four experimental conditions involving interference tasks [no interference task; visual task; verbal task; visual-plus-verbal task] and presented 15 target odours. Either recognition of the odours or free recall of the odour names was tested on one occasion, either within 15 minutes of presentation or one week later. Recognition and recall performance both showed effects of interference of visual and verbal tasks but there was no effect for time of testing. While the results may be accommodated within a dual coding framework, further work is indicated to resolve theoretical issues relating to task complexity.

Adolescent↗
PubMed1991

Effects of chlordiazepoxide and putative anxiogenics on conditioned suppression in rats.

This paper reports two experiments. In Experiment 1, the effects of chlordiazepoxide alone and in combination with a series of putative antagonists at various sites on the GABA/benzodiazepine receptor complex on conditioned suppression of operant behavior in rats were assessed. Response rates during presentation of a stimulus associated with shock (CS responding) and when only positive reinforcement is effective (pre-CS responding) were analysed. Chlordiazepoxide (10 mg/kg) significantly increased CS responding. This effect was significantly antagonised by Ro15-1788 (10 mg/kg) and by picrotoxin (1.5 mg/kg), but not by bicuculline (1.5 mg/kg) or by delta-amino-n-valeric acid (10 or 20 mg/kg). Chlordiazepoxide also significantly, albeit more slightly, increased pre-CS responding and none of the other drugs tested significantly antagonised this action, though Ro15-1788 plus chlordiazepoxide resulted in pre-CS response rates not significantly different from either chlordiazepoxide alone or control. These interactions are discussed in the context of the proposed GABA/benzodiazepine receptor complex with the conclusion that drug effects at the benzodiazepine- and picrotoxin-sensitive channel sites have an important role in mediating anxiolytic action. However, behavioral evidence of an important role for GABAa or GABAb receptors remains very limited. The second experiment studied the intrinsic actions of bicuculline, picrotoxin, and Ro15-1788 on conditioned suppression. Responding during a conditioned stimulus associated with a mild (0.125 to 0.15 mA) electric shock (CS responding) and a control rate of responding (pre-CS responding) were recorded. Bicuculline (1.5 mg/kg) and Ro15-1788 (10 mg/kg) did not significantly affect either response rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1990

Effects of agonists and antagonists at the GABA/benzodiazepine receptor on conditioned suppression in rats.

Certain drugs generally regarded as GABA agonists, such as valproate and combinations of muscimol and baclofen, have been reported to produce apparent anxiolytic effects in various animal behavioral tests. The present paper reports two experiments on the effects of these agents on conditioned suppression in rats. In the first study, muscimol (0, 1.25 micrograms/kg or 1 mg/kg), baclofen (0, 1 mg/kg) and combinations of these treatments failed to alleviate conditioned suppression. Experiment Two showed that valproate (200 mg/kg) did attenuate conditioned suppression, and that its effects were antagonised by picrotoxin (1.5 mg/kg), but not by bicuculline (1.5 mg/kg), Ro 15-1788 (10 mg/kg) or by delta-amino-n-valeric acid (10 mg/kg). The findings are discussed in the context of the proposed GABA/benzodiazepine receptor complex, with the conclusion that there is little evidence for a mediating role of GABAa or GABAb receptors in such drug actions, and that the site of valproate action is probably the chloride ion channel associated with the receptor complex.

Animals↗
PubMed1986

Molecular analyses of the effects of d-amphetamine on fixed-interval schedule performances of rats.

A series of doses (0.5 to 2.0 mg/kg) of d-amphetamine was administered to rats whose lever pressing was maintained by fixed-interval 30-s, 60-s, or 120-s schedules of reinforcement by sucrose delivery. Under both saline and d-amphetamine conditions, molecular features of responding were reliably described in terms of the distribution of postreinforcement pauses and local response rate following the onset of responding. Postreinforcement pause always varied from interval to interval but, on average, shortened under the drug. Local response rate (response rate exclusive of pause time) tended to decrease under the drug, and where acceleration occurred within runs of responses, it was reduced by the drug. All of these effects were dose-related. These findings suggest that fixed-interval behavior can be analyzed effectively at a molecular level, and that the effects of d-amphetamine are best described as disruption of temporal discrimination.

Animals↗