The lateral amygdaloid nucleus: sensory interface of the amygdala in fear conditioning

TLDR

Projections from the acoustic thalamus to the amygdala are known to mediate classical conditioning of emotional responses to auditory stimuli. The study aimed to test whether the lateral amygdaloid nucleus serves as the sensory interface of the amygdala during emotional conditioning. The authors lesioned the lateral amygdaloid nucleus in rats and assessed the resulting effects on emotional conditioning. Lesions of the lateral amygdaloid nucleus disrupted emotional conditioning while leaving nonassociative responses intact, demonstrating its essential role as the sensory interface for auditory emotional learning.

Abstract

Previous work has implicated projections from the acoustic thalamus to the amygdala in the classical conditioning of emotional responses to auditory stimuli. The purpose of the present studies was to determine whether the lateral amygdaloid nucleus (AL), which is a major subcortical target of projections from the acoustic thalamus, might be the sensory interface of the amygdala in emotional conditioning. Lesions were placed in AL of rats and the effects on emotional conditioning were examined. Lesions of AL, but not lesions of the striatum above or the cortex adjacent to the AL, interfered with emotional conditioning. Lesions that only partially destroyed AL or lesions placed too ventrally that completely missed AL had no effect. AL lesions did not affect the responses elicited following nonassociative (random) training. AL is thus an essential link in the circuitry through which auditory stimuli are endowed with affective properties and may function as the sensory interface of the amygdala during emotional learning.