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Nat Neurosci. 2000 Jan;3(1):74-9.

Different lateral amygdala outputs mediate reactions and actions elicited by a fear-arousing stimulus.

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Center for Neural Science, New York University, New York, New York 10003, USA.


Fear-arousing stimuli elicit innate reactions and can reinforce acquisition of new responses. We tested whether mechanisms mediating these conditioned stimulus (CS) properties were isomorphic or dissociable within the amygdala. Rats trained on a fear-conditioning task (CS paired with footshock) were then trained on an escape-from-fear task (EFF) in which the CS reinforced a locomotor response terminating the CS. Lateral nucleus (LA) lesions blocked acquisition of both conditioned freezing responses and the CS's reinforcement of a new response in the EFF task. Central nucleus (CE) lesions blocked conditioned freezing but not the EFF, whereas basal nucleus (B) lesions blocked the EFF but not conditioned freezing. Thus, activation of the LA by a CS seems to trigger conditioned reactions via CE and conditioned aversion via B activation, reduction of which reinforces new actions.

[Indexed for MEDLINE]

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