Dopamice

 

Much of what we know about the effects of dopamine comes from studies on rodents. Exposure to chronic mild stress leads to an "animal model of depression" characterized by decreased responsiveness to rewards and reduced sexual and aggressive behaviors. "Learned helplessness," the "forced swim test," and "effort expenditure" effectively brow-beat the little guys into a "what’s the use in trying" state, easily observable by decreased locomotion or lack of effort in going after rewards.