Effects of lesions in the central nucleus and lateral nucleus of the amygdala on fear conditioning with a visual conditioned stimulus in rats

Abstract

Lesions in the central nucleus or lateral nucleus of the amygdala have been known to interfere with the acquisition of fear conditioning when a sound is used as a conditioned stimulus (CS) . The present study examined whether or not a similar interference would occur with a visual CS. Seven rats with lesions in the central nucleus (AMY-C group), 8 with lesions in the lateral nucleus (AMY-L group), and 16 unoperated control rats were trained using a visual CS (25 W light, 3.7s duration) paired with footshock (1.0 mA, 0.5s). The behavioral index of fear conditioning was a potentiation of startle reflex in the presence of CS. All control rats and AMY-L group showed the potentiation, but AMY-C group did not. These results suggest that the lateral nucleus of the amygdala may not be involved in fear conditioning to a visual CS. It is possible that each modality of CS has a specific pathway to the central nucleus of the amygdala to mediate fear conditioning.