Post-training reversible inactivation of the rat's basolateral amygdala interferes with hippocampus-dependent place avoidance memory in a time-dependent manner

In this study, tetrodotoxin (TTX) inactivation was employed to evaluate the involvement of the rat's basolateral amygdala (BLA) in hippocampus-dependent spatial memory using a place avoidance learning task. Rats were trained in single 30 min session to avoid a 60° segment of the stable circular (80-cm diameter) arena, entering which was punished by a mild shock. Bilateral injections of TTX or saline were made either immediately, 1 or 2 h after training. Retention was tested 24 h later in a 30 min extinction session. Retention was impaired when both BLA inactivated immediately or 1 h after training, but not 2 h after training. These data indicate that activity in the BLA, at least 60 min after training, is necessary for the post-training processing of a hippocampus-dependent place avoidance memory.