Fig. 7.

Schematic representation of the proposed model of the modulation of learning processes exerted by the basal forebrain (NBM), according to which this regulation can be redundantly performed by both the basocortical, and basoamygdaloid interaction. BLA, IC, andGS represent the basolateral amygdala, insular cortex, and gustative stimulus, respectively. A, Effective modulation of taste aversion learning (CTA) after a strong reduction of basocortical cholinergic input. B,CTA is still acquired after BLA excitotoxic lesions and the subsequent disruption of the NBM–BLA–IC circuit. C,Defective basal forebrain modulation of CTA learning caused by excitotoxic lesioning of the NBM and subsequent simultaneous (although partial) deafferentation of both the cortex and BLA. D,Combination of A and B conditions resulting in the functional inactivation of both modulatory pathways.