Showing papers by "Trevor W. Robbins published in 1985"
TL;DR: Two lines of evidence are presented that show that unilateral striatal DA depletion in the rat does not affect sensory attention to visual signals of reward, but rather impairs the initiation (though not the completion) of contralateral motor acts.
Abstract: Although Parkinson's disease has traditionally been considered as a motor disorder1,2, there has been much recent interest in the nature and the neural substrates of parkinsonian dementia3,4 and cognitive dysfunction4. These disabilities, which can induce visuospatial impairment5 and visual ‘neglect’6, may also have a bearing on the controversy about the normal functions of the nigrostriatal dopamine (DA) projection and the basal ganglia2,7–9. The observations that neurones in both substantia nigra and striatum respond to sensory events in terms of neuronal firing10,11 or DA release12,13, also suggest a role for striatum in sensorimotor integration. An important behavioural correlate of this integration is the ‘sensorimotor neglect’ syndrome14 in animals with unilateral lesions of the nigrostriatal projection who fail to orient to contralateral sensory events. However, this neglect may arise not from contralateral sensory inattention14,15, but from an inability to express this sensory selection via motor output. We present here two lines of evidence that unilateral striatal DA depletion in the rat does not affect sensory attention to visual signals of reward, but rather impairs the initiation (though not the completion) of contralateral motor acts. These results not only help to clarify the function of the nigrostriatal DA projection, but also show that depletion in this system is linked specifically to a process of response initiation, which may be the fundamental impairment in Parkinson's disease.
287 citations
TL;DR: The diverse pattern of results produced by lesions induced by 6-hydroxydopamine on a variety of tasks are integrated to achieve a tentative hypothesis of coeruleocortical noradrenergic function.
Abstract: The behavioral function of the coeruleocortical system and the hypotheses implicating its role in mediating selective attention and behavioral inhibition to anxiogenic cues are evaluated. The diverse pattern of results produced by lesions induced by 6-hydroxydopamine on a variety of tasks (appetitive conditional discrimination, nonreversal shift, blocking, latent inhibition, distraction, taste aversion, neophobia, and conditioned emotional response) are integrated to achieve a tentative hypothesis of coeruleocortical noradrenergic function.
62 citations
TL;DR: It seems unlikely that the reductions in exploration previously reported after lesions of the mesolimbicocortical dopamine system at the level of anterolateral hypothalamus induced by 6-OHDA are either behaviourally specific or result solely from depletion of dopamine with the nucleus accumbens and frontal cortex.
56 citations
TL;DR: Results are interpreted as showing that d-amphetamine facilitates tracking performance as a result of its action of enhancing response switching, and supporting the hypothesis that facilitation of performance by amphetamine-like drugs depends on the effect of the drug on response output coinciding with task requirements.
Abstract: Rats were trained to respond to one of two levers under a random ratio schedule of food reinforcement. Which of the levers was correct was redetermined before each response and signalled by a light. The effects of d-amphetamine (0.2–3.2 mg/kg), chlordiazepoxide (1–8 mg/kg), and the neuroleptic alpha-flupenthixol (0.03–0.33 mg/kg) on the efficiency of rats tracking this visual cue were examined. d-Amphetamine increased the proportion of responses made on the correct lever at low and intermediate doses, but reduced the proportion at 3.2 mg/kg. At the highest dose, chlordiazepoxide produced a small increase in this measure, together with a reduction in response rate, but alpha-flupenthixol had no effect, even at a dose reducing response rate. Low doses of amphetamine also increased switching between the levers, producing a proportionately greater increase in switching from the correct lever to the incorrect lever than vice versa. The results are interpreted as showing that d-amphetamine facilitates tracking performance as a result of its action of enhancing response switching, and supporting the hypothesis that facilitation of performance by amphetamine-like drugs depends on the effect of the drug on response output coinciding with task requirements.
39 citations