THE ROLE OF 2 MAJOR CHOLINERGIC SYSTEMS IN MEMORY ACQUISITION AND RETENTION IN THE 8-ARM RADIAL MAZE

The role of the nucleus basalis magnocellularis (NBM) and the medial septum (MS) in postoperative memory acquisition and postoperative memory retention was assessed in the eight-arm radial maze task (Olton). NBM lesions and MS lesion significantly decreased choline acetyltransferase (CAT) activity in the innervated areas. Animals with MS lesions, but not NBM lesions, showed significant impairment of memory acquisition. NBM lesions induced a unique strategic pattern, but the development of strategic pattern with training was comparable to the sham-injected group. Animals with MS lesion did not develop strategic pattern with training. NBM and MS lesions did not influence either memory retention or developed strategic pattern. These results suggest that (1) MS contributes to the radial maze task; (2) the two systems have qualitatively different contributions in the radial maze task; (3) the two systems do not contribute to memory retention; (4) the two major cholinergic systems have different functions in the pathophysiology of Alzheimer's disease.