Dopamine and depression: a review of recent evidence. II. Theoretical approaches.

This paper discusses 3 behavioural approaches to depression, 'learned helplessness', reward system dysfunction and reduced responsiveness to the environment, and the role of dopamine (DA) in their related animal models. The meso-limbic and nigrostriatal DA system appears to be related primarily to responsiveness to the environment. This conclusion is discussed in relation to the clinical symptomatology of depression.