Functional organization of the rat amygdala with respect to avoidance behavior.

Bilateral electrolytic lesions in the periamygdaloid piriform cortex of female albino rats produced marked disruptive effects on the acquisition of active avoidance responses in a 1-way as well as a 2-way test situation, significantly impaired passive avoidance behavior, and inhibited feeding in a novel environment. Lesions in each of the 6 major subdivisions of the amygdala (cortical, medial, central, intercalated, lateral, and basolateral nuclei) consistently produced facilitatory effects on active avoidance behavior in 1-way as 2-way situations. Passive avoidance behavior was impaired in animals with lesions in the central, intercalated, and basolateral nuclei. Damage to the anterior amygdaloid area or the the nuclei of the lateral olfactory tract did not reliably affect active or passive avoidance behavior.