Abstract: The habenula is an important connecting node between forebrain and midbrain in mammals. This evolutionarily old brain structure is getting increased attention for its role in depression. This review describes the neuroanatomy of the habenular complex, and discusses its involvement in stress induced behavioral responses. A growing body of animal and clinical researche has focused on the influence of habenula on the monoamine systems. Recent discoveries indicate that habenula activation plays a prominent role in inhibiting serotonergic and dopaminergic neurons, which possibly leads to the depressive-like behaviors in animals under stress. They provide new insights into the study and treatment of depression. The interactions between habenular dysfunction and the HPA axis as well as the neuroimmune system in general worths further investigations in the future.

Key words: Habenula, depression, stress, 5-HT, dopamine