small region of the forebrain in front of the optic lobe; functions with the pineal gland to maintain the body’s endogenous daily (circadian) rhythms and synchronize them with the exogenous rhythms of the Earth; receives and processes information from the exogenous environment and directs the body’s systems to respond appropriately; secretes neurohormones to the pituitary gland to trigger release of hormones for reproduction, growth and development, salt/water balance, and responses to stress