Dissociable roles of the central and basolateral amygdala in appetitive emotional learning

The amygdala is considered to be a core component of the brain's fear syste m. Data from neuroimaging studies of normal volunteers and brain-damaged pa tients perceiving emotional facial expressions, and studies of conditioned freezing in rats, all suggest a specific role for the amygdala in aversive motivation. However, the amygdala may also be critical for emotional proces sing in positive or appetitive settings. Using an appetitive Pavlovian appr oach procedure we show a theoretically important dissociation in the effect s of excitotoxic lesions of the central nucleus and basolateral area of the amygdala, in the rat, Whilst central nucleus lesions impair appetitive Pav lovian conditioning, basolateral lesions do not, Together with other data, these results not only support the hypothesis that the amygdala is critical for appetitive as well as aversive learning, but are also consistent with amygdala subsystems subserving distinct aspects of emotional learning. Lesi ons of the dorsal or ventral subiculum were without effect on autoshaping, indicating the lack of involvement of hippocampal processing in this form o f emotional behaviour and emphasizing further the neural specificity of the effects seen following central amygdala lesions.