THE ROLE OF THE AMYGDALA AND DORSAL RAPHE NUCLEUS IN MEDIATING THE BEHAVIORAL CONSEQUENCES OF INESCAPABLE SHOCK

It has been argued that exposure to inescapable shock produces later b ehavioral changes such as poor shuttle box escape learning because it leads to the conditioning of intense fear, which later transfers to th e shuttle box test situation and interferes with escape. Both fear, as assessed by freezing, and escape were measured in Sprague-Dawley rats 24 hr after exposure to inescapable shock. Lesions of the basolateral region and central nucleus of the amygdala eliminated the fear that t ransfers to the shuttle box after inescapable shock, as well as the fe ar conditioned in the shuttle box by the shuttle box shocks. However, the amygdala lesions did not reduce the escape learning deficit produc ed by inescapable shock. In contrast, dorsal raphe nucleus lesions did not reduce the fear that transfers to the shuttle box after inescapab le shock, but eliminated the enhanced fear conditioning in the shuttle box as well as the escape deficit. The implications of these results for the role of fear and anxiety in mediating inescapable shock effect s are discussed.