For instance, in the rat, neurogenesis has been found to increase in response to chronic treatment with antidepressants.[41] The physiological effects of stress, often characterized by release of glucocorticoids such as cortisol, as well as activation of the sympathetic nervous system (a division of the autonomic nervous system), have been shown to inhibit the process of neurogenesis in primates.[42] Both endogenous and exogenous glucocorticoids are known to cause psychosis and depression,[43] implying that neurogenesis in the dentate gyrus may play an important role in modulating symptoms of stress and depression.[44]