INHIBITION OF INTERMEDIATE-TERM MEMORY FOLLOWING PASSIVE-AVOIDANCE TRAINING IN NEONATE CHICKS BY A PRESYNAPTIC CHOLINERGIC BLOCKER

The effects of a specific presynaptic cholinergic antagonist, toosenda nin, on memory formation following a passive avoidance training experi ence in day-old chicks was investigated. Bilateral injection of toosen danin into the neostriatal/hyperstriatal region of the chick forebrain produced memory impairment in a dose-dependent manner. Retention defi cits were apparent from 20 min following training in chicks treated wi th toosendanin, regardless of the injection time relative to training. Chicks that received injections of the drug at corresponding times pr ior to retention tests showed normal retention levels, suggesting that toosendanin has no effect on performance and memory retrieval. These results indicate an involvement of cholinergic transmission during an early stage of memory formation. (C) 1997 Academic Press.