Reversible inactivation of the medial septum or nucleus basalis impairs working memory in rats: A dissociation of memory and performance

Lidocaine-induced inactivation of the medial septum immediately after training or prior to testing in a delay radial-arm maze task produced deficits in spatial working memory that reflected impaired acquisition of the task. Injection of lidocaine into the nucleus basalis magnocellular's produced a profile of behavioral changes that indicated that temporary inactivation of this structure impaired the behavioral expression of information already stored in working memory. This appears to reflect an impairment in processes that are required for performance (i.e., attention, motivation, sensorimotor function) of the task but not for retrieval of stored information. Site-specific inactivation of the basal forebrain should help to reveal the involvement of its component structures in different aspects of cognitive function.