COMBINED SEROTONERGIC-CHOLINERGIC LESIONS DO NOT DISRUPT MEMORY IN RATS

Rats were trained on a delayed nonmatching to position task, divided i nto four groups and given the following lesions: (a) SHAM (vehicle inj ection into nucleus basalis magnocellularis (NBM) and raphe nuclei (RN ), (b) RN (5,7-dihydroxytryptamine lesions of raphe, vehicle into NBM) , (c) NBM (quisqualic acid lesion of NBM, vehicle into RN), and (d) CO MB (lesions of both RN and NBM). RN lesions had no effect on performan ce measures including accuracy (percent correct), errors of omission, bias, latencies, and magazine response rate. NBM lesions produced dela y-independent (nonmnemonic) disruptions, but performance improved over the 20 days' test. The effects of COMB lesions were no worse than NBM lesions alone. The results suggest that (a) the serotonergic system i s not essential for performance in this task, (b) NBM lesions transien tly impair nonmnemonic aspects of performance, and (c) serotonergic-ch olinergic interactions may not be essential for some cognitive process es.