Effects of hippocampal microinjections of D-amphetamine and scopolamine on active avoidance behavior in rats

Rats received bilateral injections of 20 or 40 mug. of d-amphetamine or scopolamine into the dorsal or ventral hippocampus prior to each of 8 daily training sessions in a discriminated Y-maze active avoidance task. Scopolamine, but not d-amphetamine, facilitated avoidance responding in both sites, with the effect being greatest following administration of 20 mug. into the dorsal hippocampus. On Days 9 and 10, all animals received saline injections and were tested for transfer of responding to the nondrug state. A decrement of performance occurred irrespective of whether the drug had facilitated avoidance responding. The performance changes were greater following termination of scopolamine than d-amphetamine injections, and in no case were so great as those previously reported following peripheral injections of the drugs.