Neurotoxic damage to the dorsomedial striatum exaggerates the behavioral influence of a context-specific inhibitory association mediated by the ventral hippocampus.

This study investigated the role of the dorsomedial striatum (DMS) on the acquisition of a context-specific inhibitory association acquired during training on a simple visual discrimination task. The authors have previously shown that this inhibitory association depends on the circuitry of the ventral hippocampus. The authors were interested in the anatomical and functional relationship between the hippocampus and DMS and the potential contribution the DMS makes to this inhibitory behavior. Rats with neurotoxic lesions of the DMS, or shams, were assessed on the acquisition of a visual discrimination task. Following asymptotic performance, they were given reversal training in the same or different context from the original training. The results indicated that the rats with DMS damage showed an exaggerated context-specific inhibition effect. The rats with DMS damage were also impaired on a simultaneously trained tactile/spatial discrimination, a functional effect linked to a neural circuit that includes the dorsal hippocampus. A discussion of potential pathways and mechanisms for these different effects is presented. Copyright (c) 2008 APA, all rights reserved.