Habenula

The habenula (diminutive of Latin habena, meaning "rein") is a small bilateral neuronal structure in the brain of vertebrates, that has also been called a microstructure since it is no bigger than a pea. The naming as "little rein" describes its elongated shape in the epithalamus, where it borders the third ventricle, and lies in front of the pineal gland. Although it is a microstructure each habenular nucleus is divided into two distinct regions of nuclei, a medial habenula (MHb), and a lateral habenula (LHb) both having different neuronal populations, inputs, and outputs. The medial habenula can be subdivided into five subnuclei, the lateral habenula into four subnuclei. Research has shown (Wikipedia)