Habenula

In neuroanatomy, the term originally denoted the stalk of the pineal gland (pineal habenula; pedunculus of pineal body), but gradually came to refer to a neighboring group of nerve cells with which the pineal gland was believed to be associated, the habenular nucleus. Currently, the TA term refers exclusively to this circumscript cell mass in the caudal and dorsal aspect of the dorsal thalamus, embedded in the posterior end of the medullary stria from which it receives most of its afferent fibers. By way of the retroflex fasciculus (habenulointerpeduncular tract) it projects to the interpeduncular nucleus and other paramedian cell groups of the midbrain tegmentum. Despite its proximity to the pineal stalk, no habenulopineal fiber connection is known to exist.

The habenula is involved in receiving input from the brain via the stria medullaris thalami and output to many midbrain areas involved in releasing personality-related neuromodulators, such as dopamine, norepinephrine, and serotonin (from the ventral tegmental area, locus ciruleus, and raphe cells, respectively.)