The central nucleus of the amygdala appears to play an important role in the expression of emotional behavior, including both somatic and autonomic components. For example, stimulation of the central nucleus produces the classic defense response in cats while lesions of this nucleus result in deficits in defensively conditioned cardiovascular changes in rabbits. Using autoradiographic and horseradish peroxidase techniques we propose to examine a projection of the central nucleus in the rabbit that may be an important substrate for the autonomic component of such emotional responding: a direct projection to the region of the visceral portion of the nucleus of the solitary tract and the dorsal motor nucleus of the vagus nerve. We will also examine the reciprocal pathways from the nucleus of the vagus nerve. We will also examine the reciprocal pathways from the nucleus of the solitary tract to the central nucleus. It is predicted that the results of the proposed experiments will clarify the organization of the central nucleus for the autonomic component of emotional expression and yield important data concerning the influence of the amygdala on cardiovascular regulation.