The blueprint of the vertebrate forebrain - With special reference to the habenulae.

The medial and lateral habenulae are conserved throughout vertebrate evolution, and form an integrated part in the forebrain control of behavior together with the basal ganglia, the dopamine and serotonin systems and cortex. The lateral habenula plays a role in the control of dopamine activity in the context of aversive behavior and the converse, a reward situation. These circuits are important for a value-based evaluation of the success of prior actions. The medial habenula is involved in mediating escape and freezing behavior. These structures are reviewed with a focus on the lamprey, belonging to the oldest group of now living vertebrate, showing that most aspects of the habenular structure and function have been conserved throughout vertebrate phylogeny.