We have continued to study the interactions between cortical and subcortical catecholamine systems. In particular we have investigated the altered response of subcortical dopamine systems to stress in animals with impairment of medial prefrontal cortex and hippocampus. Deefferenation of the medial prefrontal cortex results in (1) supersensitivity to DA agonists, (2) subsensitivity to DA antagonists, (3) altered subcortical DA response to stress, (4) enduring indices of DA dysregulation following a period of experiential stress. Such effects are not seen after lesions of dorsal hippocampus. Lesions of ventral hippocampus produce yet a different effect profile-enhanced exploration and amphetamine-induced locomotion, subsensitivity to DA agonists and antagonists, increased limbic DA concentration. In conclusion, the prefrontal cortex appears to play a unique role in modulating the acute response stress, and is critical in the coping response to chronic stress.
