LONG-LATENCY EVENT-RELATED POTENTIALS IN RATS - RESPONSE OF AMYGDALA,NUCLEUS-ACCUMBENS, DORSAL HIPPOCAMPUS AND FRONTAL-CORTEX TO CHANGES IN REWARD CHARACTERISTICS OF CONDITIONED-STIMULI

Circuits involving major afferents to the ventral striatum from the fr ontal cortex, amygdala and hippocampus have been implicated in the sel ective processing of conditioned stimuli predictive of 'important even ts' or reward-related processes. We utilized an animal model of event- related potentials (ERPs) to explore the relationship between these br ain areas during the performance of a conditioning/extinction task. Si gnificant reductions in the N1 component in cortex and P2 component in amygdala of the rat ERP were found as a consequence of removal of the food reward previously associated with the stimuli. Lesions of the nu cleus basalis magnocellularis were without effect on the pattern of ER P morphology changes associated with the removal of the reward. Since the N1 component of the ERP has been linked to attentional processes, these studies suggest that elimination of reward characteristics of co nditioning stimuli can lead to a specific reductions in 'attention' an d or 'sensory reaction' in frontal cortex and amygdala but not to gene ral habituation to these stimuli or in other areas of the CNS. (C) 199 8 Elsevier Science B.V.