The interpeduncular nucleus (IPN) is a phylogenetically conserved area of the brain. Anatomically, the IPN is unique in that it is primarily an unpaired structure, but receives a significant input from a paired structure, the habenula (Hb). Solely based on its anatomical connections it can be concluded that the IPN is an important integrative center for the limbic system. The IPN is highly vascularized and protrudes into the interpeduncular cistern. In some species, IPN cells having morphologic similarities to neurosecretory cells are identified. An important aspect of both the neurochemical and neuroanatomical understanding of the IPN is to determine whether important species differences exist. The observation that the biochemical measurements indicate extremely high concentrations of acetylcholine (ACh) and choline acetyltransferase (CAT) is in agreement with reports that the IPN contains a high concentration of the binding of [3H]ACh as well as other receptor ligands. Metabolic activity in the IPN is spared or increased during anesthesia, suggesting several possible behavioral functions related to sleep, to autonomic functions such as respiration, or to a generalized emotional state.
ASJC Scopus subject areas
- Clinical Neurology
- Cellular and Molecular Neuroscience