NUCLEUS BASALIS LESIONS - IMPLICATION OF BASOAMYGDALOID CHOLINERGIC PATHWAYS IN MEMORY

Previous studies have shown a lack of association between cortical cho line acetyltransferase (ChAT) activity and severity of memory impairme nt following excitotoxic lesions of the nucleus basalis magnocellulari s (NBM). It recently has been proposed that the differential effects o f NBM injections of various excitotoxins on amygdaloid and cortical Ch AT may explain this result. The present study evaluated the mnemonic e ffect of unilateral intra-NBM infusions of the excitotoxins phthalic a cid and quisqualic acid, which decrease ChAT activity primarily in the amygdala and cortex, respectively. Rats were trained in a double Y-ma ze, lesioned, and allowed to recover for 1 week prior to memory assess ment. Behavioral results showed impaired working but not reference mem ory following phthalic acid lesions, and no significant effect followi ng quisqualic acid lesions. Biochemical analysis in a second group of subjects confirmed that phthalic acid lesions produced a large decreas e in basolateral amygdaloid ChAT, but had little effect on cortical Ch AT activity. Conversely, quisqualic acid lesions produced a large decr ease in cortical, but not basolateral amygdaloid, ChAT activity. These results suggest that the NBM amygdalopetal cholinergic pathways play a role in mnemonic functioning.