DISSOCIATING THE ANTI-FEAR EFFECTS OF SEPTAL AND AMYGDALOID-LESIONS USING 2 PHARMACOLOGICALLY VALIDATED MODELS OF RAT ANXIETY

Effects of septal and amygdaloid lesions were compared in 2 models of rat ''anxiety.'' Septal lesions decreased burying behavior in the ''sh ock-probe burying test'' and increased open-arm exploration in the ''e levated plus-maze test,'' whereas amygdaloid lesions produced neither of these anxiolytic effects. However, amygdaloid lesions increased rat s' contacts of the electrified probe, an anxiolytic effect not produce d by septal lesions. Each of these distinct, anxiolytic effects of sep tal or amygdaloid lesions were displayed together in animals with lesi ons of both structures. Furthermore, the magnitude of these anxiolytic effects after combined lesions was comparable to their magnitude afte r individual lesions. Taken together, these results suggest the amygda la and the septum independently control the expression of different fe ar-related behaviors.