AMYGDALA-PREFRONTAL INTERACTIONS AND CONDITIONED BRADYCARDIA IN THE RABBIT

Damage to the amygdala or medial prefrontal cortex (mPFC) produces def icits in learned autonomic adjustments. Whether connections between th ese 2 structures are necessary for acquiring classically conditioned h eart rate (HR) decelerations was studied. Connections between them wer e interrupted by unilateral lesions of the mPFC and amygdala, but on o pposite sides of the brain. One experiment focused on the mPFC and amy gdala central nucleus and a second on the mPFC and amygdala basolatera l complex. Bilateral lesions of either structure disrupted the HR cond itioned response. The response of the 2, crossed lesioned groups also was smaller than that of the sham-operated and unilateral lesioned gro ups, but significant conditioned stimulus-evoked bradycardia occurred in both, suggesting that although interactions between the amygdala an d mPFC may normally occur during associative emotional responding, the se connections are not necessary for the acquisition of conditioned br adycardia.