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T W Robbins

Publications and source records attributed to T W Robbins.

At least 325 records · Page 18Linked to original sources
PubMed1983

Effects of d-amphetamine and apomorphine upon operant behavior and schedule-induced licking in rats with 6-hydroxydopamine-induced lesions of the nucleus accumbens.

After training under a fixed-interval 60 sec schedule of food presentation in the presence of a water tube (to permit schedule-induced licking), groups of rats received either 6-hydroxy-dopamine (6-OHDA)(8 micrograms base/2 microliters) or 0.2% ascorbate-0.9% saline vehicle bilaterally into the nucleus accumbens. 6-OHDA produced greater than 80% depletion of the catecholamines dopamine and norepinephrine and the dopamine metabolite dihydroxyphenylacetic acid in the nucleus accumbens and olfactory tubercle, but nonsignificant depletions in the corpus striatum. The behavior of the groups treated with 6-OHDA ("lesion") and vehicle ("sham") was assessed for up to 58 days postoperatively. In the first few days after 6-OHDA, the lesion group showed reductions in high rates of responding toward the end and in high rates of licking at the beginning of the fixed-interval. However, licking was increased during later portions of the fixed interval in the lesion group. d-Amphetamine (0.25-2.0 mg/kg) increased low rates but decreased high rates of schedule-controlled responding, while generally reducing licking. The lesion group showed attenuated rate-reducing effects of d-amphetamine. In contrast, the lesion group showed enhanced rate-reducing effects of apomorphine (0.025-0.1 mg/kg) on both schedule-controlled responding and schedule-induced licking. In a second determination of the effect of d-amphetamine (0.25-2.0 mg/kg), schedule-induced locomotor activity was recorded and the water tube was removed. The lesion group showed attenuated rate-increasing and rate-decreasing effects of d-amphetamine upon schedule-controlled responding and reductions in the drug-induced increases in locomotor activity. The results are discussed in terms of the functions of dopamine in the control of behavior and in the mediation of the response to d-amphetamine and apomorphine.

Animals↗
PubMed1980

Selective disruption of displacement behaviour by lesions of the mesolimbic dopamine system.

In the wild, organisms generally allocate their time among many behavioural tendencies in response to both current and anticipated motivational requirements. However, activities that are apparently 'irrelevant' often intrude, either during conflict between these behavioural tendencies, or when a strong tendency is thwarted. These 'irrelevant' activities are called displacement behaviours and are widely documented in the ethological literature. We report here that an experimental analogue of displacement behaviour in the rat depends upon the integrity of the mesolimbic dopaminergic projection to the nucleus accumbens septi, olfactory tubercle and associated structures of the forebrain.

Animals↗
PubMed1980

An observational method for quantifying the behavioural effects of dopamine agonists: contrasting effects of d-amphetamine and apomorphine.

A novael means of measuring and analysing behavioural effects of dopamine agonists is described and illustrated by a comparison of the effects of d-amphetamine and apomorphine in the rat. d-Amphetamine (0--15 mg/kg IP) produced significant dose- and time-dependent changes in responses such as locomotion, rearing and sniffing, but not in licking or gnawing. In contrast, apomorphine (0--5 mg/kg SC) produced significant increases in licking and gnawing, as well as in locomotion and sniffing, but no changes in rearing. The results are discussed in comparison with those obtained by other methods, such as photocell beam interruptions or sterotypy rating scales, and may be of importance in elucidating the functions of the forebrain dopamine projections.

Animals↗
PubMed1978

Pipradrol enhances reinforcing properties of stimuli paired with brain stimulation.

The hypothesis that a psychomotor stimulant drug (pipradrol) enhances the reinforcing effects of stimuli paired with reinforcing brain stimulation was tested using a conditioned reinforcement paradigm. Rats were trained to discriminate between two stimuli (S+ and S-) to obtain ICS in the lateral hypothalamus by pushing a panel in the presence of S+. In a subsequent preference test, ICS was no longer available, but responding on one of two novel levers now produced S+, whereas responding on the other lever produced S-. Four groups of four rats received 0, 5, 10 or 15 mg/kg pipradrol. Doses of 5 and 10 mg/kg significantly enhanced the preference for S+ over S-. These doses increased responding for S+, but had no effect on responding for S-. These results support the hypothesis tested, and suggest that pipradrol potentiates the effects of conditioned reinforcement.

Animals↗
PubMed1978

Effects of 6-hydroxydopamine lesions of the nucleus accumbens septi and olfactory tubercle on feeding, locomotor activity, and amphetamine anorexia in the rat.

Bilateral 6-hydroxydopamine lesions of the nucleus accumbens septi (NAS) and olfactory tubercle (OT) caused enhanced intake of wet mash in 23-hr-food-deprived rats tested in photocell activity cages during restricted 30-min sessions. This mild hyperphagia was accompanied by a significant hypoactivity in the group with NAS/OT lesions. No hyperphagia was observed during a prolonged 120-min test session or in free-feeding tests conducted in the home cage. Anorexia induced by d-amphetamine (.5 and 1.5 mg/kg) was unaltered by the lesion, although the locomotor stimulant action of the drug was attenuated. A second experiment showed that the NAS/OT lesion also enhanced food intake in the photocell cages during 30-min sessions with dry food pellets but that food-associated drinking was concomitantly reduced. The results are consistent with the hypothesis that the behavioral changes caused by mesolimbic neuron destruction result in part from an inability to switch from one behavioral activity to another.

Anorexia↗
PubMed1977

Effects of chlordiazepoxide on tail pinch-induced eating in rats.

The effects of 5, 10, and 20 mg/kg chlordiazepoxide on tail pinch (TP)-induced behavior were investigated. Five mg/kg enhanced TP-induced eating in terms of both latency and duration. Twenty mg/kg had decremental effects. All doses of the drug reduced the incidence of clip-directed behavior, but increased locomotor activity during the TP trials in a dose-dependent manner. On control trials, the drug increased locomotor activity at the low dose and eating at the high dose. The results are examined in terms of the various behavioral actions of the minor tranquilizers. The implications for the behavioral and neuropharmacological mechanisms underlying TP-induced and other forms of stimulus-bound behavior are discussed.

Animals↗
PubMed1976

The effects of d-amphetamine on temporal discrimination in the rat.

The effects of d-amphetamine on temporal discrimination in the rat were studied. Rats were trained on a two-manipulandum task involving the discrimination between two tones differing only in duration. d-Amphetamine (0.1 - 1.6 mg/kg) disrupted performance on this task, although not in an obvious dose-related manner. Lever biases were enhanced by the drug, but inconsistenly among rats. Enhanced lever bias did not necessarily correlate with deterioration of performance. The drug lengthened both response latency and the performance of terminal components of the operant chain. However the characteristic pattern of response latencies produced by the two tones was not altered significantly by the drug. The results are discussed in terms of whether the drug disrupts discrimination performance by a direct effect on processes of temporal discrimination or indirectly, by its other effects on behavior.

Animals↗
PubMed1976

Alpha-flupenthixol-induced hyperactivity by chronic dosing in rats.

Socially reared and isolation-reared rats treated chronically since weaning with alpha-flupenthixol showed elevated levels of spontaneous locomotor activity compared with control treated rats. However, chronic apomorphine treatment had no effect on spontaneous locomotor activity. Chronic alpha-flupenthixol treatment enhanced stereotyped behaviour after 1.5 mg/kg d-amphetamine or 0.5 mg/kg apomorphine in the socially reared condition. 'Spontaneous stereotypies' were also observed in the chronic alpha-flupenthixol-treated animals. Chronic apomorphine treatment did not affect stereotyped responding. The results are discussed in terms of 'behavioural supersensitivity'.

Animals↗
PubMed1975

The effects of psychomotor stimulants on stereotypy and locomotor activity in socially-deprived and control rats.

Using measures of locomotor activity and stereotypy, dose-response curves to several psychomotor stimulant drugs were obtained on rats reared in deprived or normal environments. At both 0.5 and 1.5 mg/kg d-amphetamine, the deprived rats exhibited more intense stereotyped behavior than the control rats. At 5.0 mg/kg, both groups showed maximum response. However, there was no significant difference between the two groups in locomotor response. A similar pattern of results was found for pipradrol, cocaine, and apomorphine. The findings show that different social and environmental experience can modify the response to dopaminergic stimulating agents. The results also suggest that stereotyped behavior should not be considered on the same continuum as locomotor activity. These two behaviors may be mediated by different mechanisms.

Amphetamine↗