Approach and Avoidance Processing: Investigating a Rostrocaudal Gradient in the Nucleus Accumbens Core

The nucleus accumbens is a site of integration of positively and negatively valenced information. While a rostrocaudal topographical gradient in valence processing has been found in the accumbens shell, a potential gradient has not fully been explored in the core in relation to its role in motivation in response to conditioned cues. In the current study, rats were trained to associate visual cues with appetitive, aversive and neutral outcomes. In a test of motivational bias, the aversive and appetitive cues were superimposed in a maze arm and rats' exploratory bias was measured for this arm vs. a neutral cued arm. Animals receiving GABA receptor agonists in the caudal region displayed a bias in the direction of aversion, whereas those undergoing inactivation of the rostral core displayed an ambivalence similar to controls, with an additional behavioural difference of augmented chewing. This suggests a rostrocaudal differentiation in valence processing in the core.M.A