EFFECTS OF MUSCIMOL APPLIED TO THE BASOLATERAL AMYGDALA ON ACQUISITION AND EXPRESSION OF CONTEXTUAL FEAR CONDITIONING IN RATS

The amygdala is known to be important for normal aversive Pavlovian le arning in the rat. The relative contribution of the amygdala to the le arning vs. performance of conditional fear with the GABA(a) agonist mu scimol was assessed. Rats were prepared with cannulas aimed at the bas olateral amygdala and trained in a contextual fear conditioning paradi gm in which each subject received a series of footshocks in a distinct ive observation chamber. Conditional responses evoked after exposure t o the observation chamber were assessed 24 hr later. Rats that were pr etreated with muscimol before performance showed a significantly atten uated fear response, and injections made before acquisition resulted i n a much smaller decrement in conditional fear measured 24 hr after tr aining. These results indicate that acquisition-related processes that may be occurring within the amygdala are more difficult to disrupt th an those associated with performance.