Effects of desipramine and fluvoxamine on timing behaviour investigated with the fixed-interval peak procedure and the interval bisection task (original) (raw)
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The effects of tranquillizing drugs on timing behaviour in rats
Psychopharmacologia, 1975
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, suggest...
Behavioural Processes, 2014
The goal of our study was to characterize the relationship between intertemporal choice and interval timing, including determining how drugs that modulate brain serotonin and dopamine levels influence these two processes. In Experiment 1, rats were tested on a standard 40-s peak-interval procedure following administration of fluoxetine (3, 5, or 8 mg/kg) or vehicle to assess basic effects on interval timing. In Experiment 2, rats were tested in a novel behavioral paradigm intended to simultaneously examine interval timing and impulsivity. Rats performed a variant of the bi-peak procedure using 10-s and 40-s target durations with an additional "defection" lever that provided the possibility of a small, immediate reward. Timing functions remained relatively intact, and 'patience' across subjects correlated with peak times, indicating a negative relationship between 'patience' and clock speed. We next examined the effects of fluoxetine (5 mg/kg), cocaine (15 mg/kg), or methamphetamine (1 mg/kg) on task performance. Fluoxetine reduced impulsivity as measured by defection time without corresponding changes in clock speed. In contrast, cocaine and methamphetamine both increased impulsivity and clock speed. Thus, variations in timing may mediate intertemporal choice via dopaminergic inputs. However, a separate, serotonergic system can affect intertemporal choice without affecting interval timing directly.
Pharmacology Biochemistry and Behavior, 1980
A comparison of the effects of d-amphetamine, cocaine, irnipramine and pentobarbital on local and overall rates of responding maintained under a four-component multiple fixed-interval schedule. PHARMAC. BIOCHEM. BEHAV. 12(6) 899-907, 1980.-Key pecking of pigeons was maintained under a four-component multiple fixed-interval schedule with values of 1-min, 3-min, 5-min and 10-min. Each schedule value was correlated with a different key color, each of which controlled distinctively different performances. This schedule generated a range of response rates both within and across the different interval components that permitted a direct comparison of drug effects on local and overall rates of responding, d-Amphetamine, cocaine, imipramine and pentobarbital all increased low local response rates at doses that did not affect or decreased higher rates within each fixed interval. Similar effects were obtained when different overall rates of responding were analyzed except that imipramine and pentobarbital also increased the highest overall rates occurring under the l-rain schedule. d-Amphetamine Cocaine Imipramine Pentobarbital Operant behavior Rate-dependency Pigeons Schedules of reinforcement
Psychopharmacology, 1976
The lever-pressing behaviour of three rats was maintained by a schedule in which food reinforcement was obtained by any response which was emitted at least 15 s after the previous response (DRL 15s). When performance on this schedule had stabilised, the animals were presented intermittently with 1-min periods of a white noise stimulus, the termination of which was accompanied by the delivery of a mild electric footshock. This procedure let to reliable increases in response rates furing the stimulus although responding at other times continued to be appropriate to the DRL 15-s schedule. Administration of the benzodiazepine chlordiazepoxide (1, 3, 10, 17 and 30 mg/kg) and of ripazepam (1, 3, 10, 30 and 56 mg/kg), a non-benzodiazepine reported to have anxiolytic properties, increased response rates on the DRL baseline while decreasing the acceleration of responding produced by the preshock stimulus. Baseline response rates were also increased by d-amphetamine (0.25, 0.5, 1.0 and 2.0 mg/kg) and at the higher doses this drug completely abolished the accelerated responding during the preshock stimulus. Although the effects of chlordiazepoxide and ripazepam are consistent with the suggestion that these drugs may attenuate the behavioural effects of aversive stimuli, in this experiment the behavioural effects of d-amphetamine were similar in many respects.
The Psychological Record, 2007
Response variability, a fundamental characteristic of behavior, may be in some cases an induced effect of reinforcement schedules. Research on schedule-induced response variability has shown that continuous reinforcement results in less variability than intermittent reinforcement schedules. Studies on the effects of intermittency of reinforcement, periodicity of reinforcement, and type of schedule have resulted in mixed findings. Contingencies have also been arranged to directly influence operant response variability. These include lag reinforcement schedules, differential reinforcement of novel behavior, differential reinforcement of less frequent behavior, and percentile reinforcement schedules. These procedures are discussed in terms of practicality and implications for use in applied settings. Contingencies and treatment packages that indirectly influence response variability are addressed in terms of response allocation, response generalization, and response covariation. Studies on the effects of a variety of other variables on response variability are also reported, such as levels of food deprivation and drugs. Finally, directions for applied research in response variability are suggested.
Effects of methylphenidate and d-amphetamine on timing in the rat?
Pharmacology Biochemistry and Behavior, 1987
Rats were trained to press a lever for food pellets prowded according to a fixed interval 60-sec schedule of reinforcement Probe trials (peak trials) assessed responding over two-mm periods with no pellet dehvered The low rates of responding found early and late in probe trials were increased by methylphemdate and 1 0 mg/kg d-amphetamine (rate-dependent effect) Further, the mean ume of responding (peak time) was shortened for both drugs (timing effect) Temporal discrimination Rate-dependent effect Psychoactive stimulant Rat Methylphenldate Amphetamine
Psychopharmacology, 2000
Previous studies have shown that d-amphetamine, a dopamine (DA) indirect agonist, alters operant responding with respect to the behavior maintained on a differential reinforcement of low-rate (DRL) schedule of reinforcement. These behavioral changes have been presumed to result from drug-induced hyperdopaminergia that leads to activation of DA receptors. This study investigated the acute dose effects of DA receptor subtype-selective agonists on the performance of DRL 10-sec behavior by rats. SKF38393 (a D1 receptor agonist) and quinpirole (a D2/D3 receptor agonist) were able to dose-dependently disrupt DRL 10-sec behavior by decreasing the total responses, the non-reinforced responses, and the peak rate of response. Bromocriptine (a D2/D3 receptor agonist) produced a significantly different pattern of behavioral changes when examined during two distinct time phases (15 min and 3 hr after the drug injection). DRL responding was only altered at higher doses of bromocriptine in the second phase as indicated by decreasing reinforced responses and peak rate, together with an increase of burst responses. In contrast to the D1 and D2/D3 receptor agonists, PD168077 (a D4 receptor agonist) did not affect DRL 10-sec behavior. None of these tested drugs affected DRL 10-sec behavior in a manner similar to that of d-amphetamine. These findings show that there are differential effects on the performance of DRL 10-sec behavior when drugs are able to preferentially activate D1, D2/D3 and D4 receptors, supporting the assertion that there is functional heterogeneity of the DA receptor subtypes.
Psychopharmacology, 1994
The effects of four serotonin (5-HT)-IA compounds (buspirone, gepirone, ipsapirone and zalospirone) were compared with 5-hydroxytryptophan (5-HTP) [a 5-HT precursor with antidepressant (AD) efficacy], and diazepam (a benzodiazepine anxiolytic), on a differential-reinforcement-of-low-rate 72-s (DRL 72-s) schedule. Past research has shown that AD and anxiolytic compounds each have distinct effects on the DRL 72-s interresponse time (IRT) distribution profile. In the present paper, the profile of the IRT distribution was quantitatively characterized by three metrics: burst ratio, peak location and peak area. 5-HTP shifted the IRT distribution peak toward longer IRT durations, increased reinforcement rate and decreased response rate. The profile of the IRT distribution was not disrupted by 5-HTP. Diazepam disrupted the IRT distribution and increased bursting. In general, the arylpiperazine, 5-HT1A compounds increased reinforcement rate, decreased response rate and disrupted the profile of the IRT distribution. The effects of the four arylpiperazine 5-HT1A compounds on the IRT distribution profile were different from the AD profile of 5-HTP and the benzodiazepine anxiolytic profile of diazepam. Disruption of the IRT distribution by buspirone, gepirone, ipsapirone and zalospirone may result from decreased 5-HT transmission mediated by the presynaptic, somatodendritic 5-HT1A receptor.
Behavioural Processes, 2007
Previous research indicates that dopamine controls both the speed of an internal clock and sharing of resources between the timer and other cognitive processes . For example, dopamine agonist methamphetamine increases the speed of an internal clock and resets timing after a gap, while dopamine antagonist haloperidol decreases the speed of an internal clock and stops timing during a gap . Using a 20-s peak-interval procedure with gaps we examined the acute effects of clozapine (2.0 mg/kg i.p.), which exerts differential effects on dopamine and serotonin in the cortex and striatum, two brain areas involved in interval timing and working memory. Relative to saline, clozapine injections shifted the response functions leftward both in trials with and without gaps, suggesting that clozapine increased the speed of an internal clock and facilitated the maintenance of the pre-gap interval in working memory. These results suggest that clozapine exerts effects in different brain areas in a manner that allows for the pharmacological separation of clock speed and working memory as a function of peak trials without and with gaps.