Habenular nuclei

Habenular nuclei
Mesal aspect of a brain sectioned in the median sagittal plane. The habenular nuclei are not labeled directly, but after expanding, look to region with 'habenular commissure', 'pineal body', and 'posterior commissure'
Details
Identifiers
Latin	nucleus habenularis lateralis, nucleus habenularis medialis
TA	A14.1.08.503 A14.1.08.504
FMA	62372
Anatomical terms of neuroanatomy []

The Habenular nuclei, Latin for "little rein," acts as a regulator of key central nervous system neurotransmitters, connecting the forebrain and midbrain within the epithalamus. Although predominantly studied for its demonstration of asymmetrical brain development and function, in recent years many scientists have begun to examine the Habenular nuclei's role in motivation and behavior as it relates to an understanding of the physiology of addiction.

The habenular nuclei comprise a small group of nuclei that are part of the epithalamus of the diencephalon, and is located just above the thalamus and is divided into two asymmetric halves, the medial habenula (MHb) and the lateral habenula (LHb) that regulate monamines, such as dopamine and serotonin. Information from the posterior septum and a portion of Broca's area feeds into the MHb, and a region of the hypothalamus, nucleus accumbens, ventral pallidum, globus pallidus, and a portion of Broca's area all feed into the LHb. As a whole, this complexly interconnected region is part of the dorsal diencephalic conduction (DDC) system, responsible for relaying information from the limbic system to the midbrain, hindbrain, and medial forebrain.

Habenula Nuclear divisions:

The pineal gland is attached to the brain in this region.

Nerve impulses from the habenular nuclei are transmitted to the septal nuclei via the stria medullaris, which is found on the medial surface of the thalamus.

Recent exploration of the Habenular nuclei has begun to associate the structure with an organism's current mood, feeling of motivation, and reward recognition. Previously, the LHb has been identified as an "anti-reward" signal, but recent research suggests that the LHb helps identify preference, helping the brain to discriminate between potential actions and subsequent motivation decisions. In a study using a Pavlovian conditioning model, results showed an increase in the habenula response. This increase coincided with conditioned stimuli associated with more aversive punishments (ie. electric shock). Therefore, researchers speculate that inhibition or damage to the LHb resulting in a failure to process such information may lead to random motivation behavior.