Autonomic responses accompanying conditioned and unconditioned alimentary reactions in amygdalo-hypothalamically lesioned dogs.

Lesions in the amygdalo-hypothalamic system decreased conditioned and unconditioned alimentary responses in five dogs. During three postoperative months no improvement was observed. The introduction of the new food reward (chosen for each dog as the most preferred) produced a sudden or progressive increase of conditioned and unconditioned alimentary performance. In the cardiac responses accompanying postoperative conditioned and unconditioned alimentary reactions, the lack or diminution of the decelerative response during food .consumption and a less pronounced postoperative acceleration of heart rate during conditioned stimuli were observed. Conditioned and unconditioned salivary responses decreased postoperatively and the pattern of the salivary responses varied individually. The results support the hypothesis that damage of amygdalo-hypothalamic system produces a decrease of the hedonic values of the usually used food rewards. Decrease or lack of the decelerative cardiac response during eating may reflect this ahedonic state.