Innate and conditioned reactions to threat in rats with amygdaloid lesions.

Abstract

Gave 8 male albino rats control operations and 10 Ss large radio-frequency lesions of the amygdaloid area. Lesioned Ss showed reduced freezing to an immobile cat or to previously neutral stimuli associated with footshock. These Ss also failed to avoid either the immobile cat or an approaching shock prod. In a 2nd experiment with 16 Ss, smaller electrolytic lesions, largely involving the corticomedial amygdaloid nuclei, produced similar results. This pattern of alterations of reactivity to unconditioned and conditioned threat stimuli suggests that the amygdaloid area has a central role in the regulation of defensive reactions. (PsycINFO Database Record (c) 2006 APA, all rights reserved)