Damage to the lateral and central, but not other, amygdaloid nuclei prevents the acquisition of auditory fear conditioning

It is well established that the amygdala plays an essential role in Pavlovi an fear conditioning, with the lateral nucleus serving as the interface wit h sensory systems that transmit the conditioned stimulus and the central nu cleus as the link with motor regions that control conditioned fear response s. The lateral nucleus connects with the central nucleus directly and by wa y of several other amygdala regions, including the basal, accessory basal, and medial nuclei. To determine which of these regions is necessary, and th us whether conditioning requires the direct or one of the indirect intra-am ygdala pathways, we made lesions in rats of the lateral, central, basal, ac cessory basal, and medial nuclei, as well as combined lesions of the basal and accessory basal nuclei and of the entire amygdala. Animals subsequently underwent fear conditioning trials in which an auditory conditioned stimul us was paired with a footshock unconditioned stimulus. Animals that receive d lesions of the lateral or central nucleus, or of the entire amygdala, wer e dramatically impaired, whereas the other lesions had Little effect. These findings show that only the lateral and central nuclei are necessary for t he acquisition of conditioned fear response to an auditory conditioned stim ulus.