Interaction between raphe dorsalis and nucleus basalis magnocellularis in spatial learning.

We compared the effects on spatial learning of an ibotenic acid lesion of the nucleus basalis magnocellularis (NBM), a 5, 7-dihydroxytryptamine lesion of the raphe dorsalis (RD) and a combined NBM and RD lesion. The RD lesion reduced serotonin levels, and the NBM lesion reduced cholineacetyltransferase (ChAT) activity in the cortex. Although RD lesions alone did not affect spatial learning in the water-maze, the lesion aggravated the spatial navigation deficit produced by NMB lesioning. The current results suggest a functional interaction between the RD and NBM in spatial navigation.