Thus, nonhuman primate research is essential to understand the neural substrate that links cognition and affect to the function of internal organs. The cognitive and affective networks, present in monkeys, are largely absent in rats. In rats, cortical influences over the adrenal medulla and the kidney originate mainly from 2 motor areas and adjacent somatosensory cortex. Together, the 3 networks can mediate the effects of stress and depression on organ function and provide a concrete neural substrate for some psychosomatic illnesses. They provide a link between how we think and feel and the function of the adrenal medulla. The cognitive and affective networks are located in regions of cingulate cortex. The motor areas provide a link between body movement and the modulation of stress. These motor areas are involved in all aspects of skeletomotor control, from response selection to motor preparation and movement execution. The largest influence originates from a motor network that includes all 7 motor areas in the frontal lobe. Each of these networks has a human equivalent.

In monkeys, the cortical influence over the adrenal medulla originates from 3 distinct networks that are involved in movement, cognition, and affect. In rats, we also examined multisynaptic connections with the kidney. Which regions of the cerebral cortex are the origin of descending commands that influence internal organs? We used transneuronal transport of rabies virus in monkeys and rats to identify regions of cerebral cortex that have multisynaptic connections with a major sympathetic effector, the adrenal medulla.

Adrenal gland cortex and medulla