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Biomedical subjects

D J Sanger

Publications and source records attributed to D J Sanger.

136 records · Page 8Linked to original sources
PubMed1976

Rate-dependent effects of drugs: a review of the literature.

It has been claimed that the effects of amphetamines on schedule-controlled behavior depend to a large extent on the rate of responding in control conditions. A review of the literature shows that there is considerable support for this hypothesis if the behavior is not suppressed by aversive procedures, is not under the control of powerful external stimuli or is not occurring very infrequently. The extension of a rate-dependency hypothesis to the effects of other drugs has less empirical support, however. It is argued that many of the procedures used for studying rate-dependent drug effects do not provide critical tests of the hypothesis. If it is to be shown unequivocally that it is rate of operant responding which determines the behavioral effects of drugs, procedures are needed in which other varibles such as reinforcement frequency are more adequately controlled.

Amphetamines↗
PubMed1976

The effects of d-amphetamine on the temporal control of operant responding in rats during a preshock stimulus.

The operant behavior of six rats was maintained by a random-interval schedule of reinforcement. Three-minute periods of noise were superimposed on this behavior, each period ending with the delivery of an unavoidable shock. Overall rates of responding were generally lower during the periods of noise than in its absence (conditioned suppression). These suppressed response rates also exhibited temporal patterning, with responding becoming less frequent as each noise period progressed. The effects of d-amphetamine on this behavioral baseline were then assessed. In four animals the relative response rates during the noise and in its absence suggested that the drug produced a dose-related decrease in the amount of conditioned suppression. However, this effect was often due to a decrease in the rates of responding in the absence of the preshock stimulus, rather than to an increase in response rates during the stimulus. Temporal patterning in response rates during the preshock stimulus was abolished, an effect that was interpreted in terms of rate-dependent effect of d-amphetamine. This study thus extends rate-dependent analyses of the effects of amphetamines to the patterns of operant behavior that occur during a preshock stimulus, and which have been discussed in terms of the disrupting effects of anxiety on operant behavior.

Acoustic Stimulation↗
PubMed1975

The effects of tranquillizing drugs on timing behaviour in rats.

Timing behaviour was generated in rats by a schedule which required responses to be spaced at least 15 sec apart in order for them to produce food reinforcement (DRL 15 sec). The behaviour maintained by this schedule was then studied after administration of chlordiazepoxide, phenobarbitone and chlorpromazine. Several doses of both chlordiazepoxide and phenobarbitone were found to disrupt timing behaviour by increasing overall response rates although the highest dose of each of these two drugs produced sedative effects. Chlorpromazine produced mainly a decrease in overall response rates. Analysis of performance in terms of interresponse times (IRTs) showed that both chlordiazepoxide and phenobarbitone markedly increased the percentage of IRTs less than 1.5 sec in duration (response bursts). Chlorpromazine had no consistent effect on response bursts. Reduction of the animals' body weights from 85% to 75% of their preexperimental levels had no effect on operant performance, suggesting that the effects of the drugs were probably not due to actions on motivational processes.

Animals↗
PubMed1975

Effects of d-amphetamine on the behavior of pigeons maintained by a second-order schedule of reinforcement.

The effects of various doses of d-amphetamine were studied on the responding of two pigeons exposed to a second-order schedule of reinforcement. With this schedule, food was presented following the completion of a sequence of three 2-minute fixed-interval components. A visual stimulus was presented at the completion of each fixed interval, including the one which was terminated with food. The pigeons' behavior was characterized by a pause immediately after each stimulus presentation followed by a gradual increase in response rate as the interval progressed. d-Amphetamine was found to increase the low rates of responding which occurred early in each interval and to decrease the high rates of responding at the end of each interval. These effects occurred whether responding preceded the presentation of food or the brief stimulus alone.

Animals↗
PubMed1975

Rate-dependent effects of drugs on the variable-interval behavior of rats.

Three rats were exposed to a variable-interval (VI) schedule of food reinforcement and three were exposed to the same VI schedule but with the added constraint that reinforcement could follow only a response which occurred at least 5 seconds after the preceding response. The rats exposed to this pacing requirement responded at considerably lower rates, but obtained only slightly fewer reinforcers than those exposed to the simple VI schedule. The effects of d-amphetamine were found to be dependent on the schedule which maintained behavior. This drug produced a dose-related decrease in rates of responding maintained by the unpaced VI schedule but a dose-related increase in the much lower rates maintained by the paced VI schedule. The effects of chlordiazepoxide were not so clearly schedule-dependent although there were some differences between the effects of this drug on responding maintained by the two schedules. These results support the view that the effects of d-amphetamine depend critically on the rate of the response under investigation, but this does not appear to be the case for chlordiazepoxide.

Animals↗