Differential involvement of the right and left amygdalae in expression of memory for aversively motivated training.

The present study investigated possible lateralization of amygdala involvement in memory for aversively motivated training. Rats with bilateral cannulae aimed at the amygdalae were trained in a one-trial inhibitory avoidance task. Twenty-four h or 10 days later, animals received bilateral pre-test microinjections of either vehicle, 2% lidocaine, or unilateral infusions of each simultaneously. Five min after the infusions, retention was tested. Retention latencies of rats given bilateral lidocaine or unilateral lidocaine into only the right amygdala were significantly lower than controls. These results suggest that the right and left amygdalae may make differential contributions to the expression of memory, and that the contribution of the right amygdala may be more important to the expression of memory for aversively motivated training.