Anatomical substrates for neuroleptic-induced reward attenuation and neuroleptic-induced response decrement.
Rats were implanted with bilateral indwelling cannulae, in the nucleus accumbens (NAS), anterodorsal striatum (ADS) or basolateral amygdala (BLA). Administration of sulpiride to the NAS reduced spontaneous locomotion, caused a time-independent suppression of lever pressing on a random-interval 30sec schedule of food reinforcement, and reduced preference for a weak 0.7% sucrose solution over water without affecting the total volume of fluid consumed. Administration of sulpiride to the ADS did not affect spontaneous locomotion, but caused a time-dependent response decrement in both operant behaviour and consumption of 0.7% sucrose. Administration of sulpiride to the BLA had no effect in any of these tests. However, at all three infusion sites, sulpiride increased the consumption of a 34% sucrose solution. The data suggest a preferential involvement of the mesolimbic dopamine system in neurolepticinduced attenuation of reinforcer value, and a primary role of the nigrostriatal dopamine system in neuroleptic-induced time-dependent response decrements.
Department of Psychology, City of London Polytechnic, Old Castle St, London E1 7NT UK.
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Phillips
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Willner
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Muscat