A functional role of the amygdala in rats living in a semi-naturalistic risky environment

Abstract

There is considerable evidence that the amygdala is involved in the processing and expression of emotions, particularly fear. It would therefore be plausible to expect that amygdala-coded fear would also influence voluntary decisions on feeding and foraging in animals living in dangerous environments. The studies presented in this dissertation explore a functional role of the amygdala in rats living in a semi-naturalistic "closed economy" setting where all nutritional resources are procured at the risk of receiving random shocks in a foraging area. The first study revealed that amygdala-coded fear influences the animal's voluntary feeding behavior, but the amygdala is not necessary for the animal's voluntary avoidance of the foraging area. The second study showed that the amygdala is not necessary for either feeding or foraging behavior when the danger is signaled by a cue (predictable fear environment). The final study explores how amygdala-coded fear influences circadian rhythms in rats and how the amygdala interacts with the superchiasmatic nucleus to anticipate times of danger and safety.