Stressor Controllability
Pairs of rats were housed together in cages with dividers down the middle. One of the rats in each pair had access to an OFF lever, but the other did not. Each time the cage was electrified, the rat in control turned off the shock for both. Though the 2 rodents received identical shocks, only the yoked rat showed signs of chronic stress: weight loss, ulcers, and increased susceptibility to cancer. (”Stressor controllability modulates stress-induced dopamine and serotonin efflux and morphine-induced serotonin efflux in the medial prefrontal cortex.”) The beneficial physiological and mental effects of controlling a stressor appear to come from dopamine. Individuals with high pain thresholds have more dopamine in their accumbens.