Limbic cortical-ventral striatal systems underlying appetitive conditioning

Abstract

Publisher Summary This chapter describes the results of the experiments involving excitotoxic lesions of different nodes of circuit, in an attempt to understand the functions of corticostriatal loops, involving the nucleus accumbens (NAcc) and associated limbic circuitry that are implicated in reward and motivational processes. In the studies, the chapter investigated the effects of manipulations to the NAcc core and shell and anterior cingulate cortex, as well as the central nucleus and basolateral area of the amygdala and the dorsal and ventral subiculum, on a number of theoretically well understood animal learning paradigms. It is found that NAcc as a critical site for the arousing, or modulatory, influence of Pavlovian appetitive conditioned stimuli on ongoing motor performance, including instrumental behavior and locomotor approach. This has been demonstrated clearly by Pavlovian-to-instrumental transfer (PIT) experiments. If an animal is trained to press a lever for food and subsequently tested in extinction, presentation of a Pavlovian conditioned stimulus (CS) that predicts the same food increases the rate of lever-pressing. Lesions of the NAcc core impair the basic PIT effect, as does systemic treatment with the dopamine receptor antagonist pimozide, leading one to speculate that the ability of an appetitive Pavlovian CS to potentiate instrumental behavior depends on the mesolimbic dopamine system.