Cortical substrates of taste aversion learning: Direct amygdalocortical projections to the gustatory neocortex do not mediate conditioned taste aversion learning

Abstract

The gustatory neocortex (GN) receives direct projections from the lateral and basolateral amygdaloid nuclei. Amygdalocortical afferents ascend to the GN via the external capsule and the claustrum. The involvement of these amygdalocortical projections in conditioned taste aversion (CTA) learning was examined by producing lesions within the GN, the amygdaloid complex, or the external capsule and claustrum caudal to the GN. The complete destruction of amygdalocortical projections by lesions of the external capsule was verified following behavioral testing both by anterograde degeneration histology and by retrograde fluorescent transport experiments. Elimination of amygdalocortical input to the GN failed to significantly disrupt CTA acquisition, whereas lesions of the GN or amygdaloid complex produced reliable CTA learning impairments. These results are inconsistent with a current hypothesis which suggests that ascending amygdalocortical projections to the GN may mediate CTA learning.