Dorsal tegmental nucleus

The dorsal tegmental nucleus is located in the brain stem near the midline. Two nuclei exist in both hemispheres. The DTN is generally subdivided into four parts called partes centralis, ventromedialis, anterior, and posterior.{{cite journal|vauthors=Herkenham M, Nauta WJ| title=Efferent connections of the habenular nuclei in the rat. | journal=J Comp Neurol | year= 1979 | volume= 187 | issue= 1 | pages= 19–47 | pmid=226566 | doi=10.1002/cne.901870103 | s2cid=25866654 | url=https://pubmed.ncbi.nlm.nih.gov/226566 }}

DTN contains a dense population of GABAergic cells.{{cite journal|vauthors=Allen GV, Hopkins DA| title=Mamillary body in the rat: topography and synaptology of projections from the subicular complex, prefrontal cortex, and midbrain tegmentum. | journal=J Comp Neurol | year= 1989 | volume= 286 | issue= 3 | pages= 311–36 | pmid=2504784 | doi=10.1002/cne.902860303 | s2cid=29423728 | url=https://pubmed.ncbi.nlm.nih.gov/2504784 }} {{cite journal|vauthors=Wirtshafter D, Stratford TR| title=Evidence for GABAergic projections from the tegmental nuclei of Gudden to the mammillary body in the rat. | journal=Brain Res | year= 1993 | volume= 630 | issue= 1–2 | pages= 188–94 | pmid=8118685 | doi= 10.1016/0006-8993(93)90656-8| s2cid=25282593 | url=https://pubmed.ncbi.nlm.nih.gov/8118685 }} In the rat, few also express calbindin (CB) or calretinin (CR). Many of the DTN GABAergic cells do express parvalbumin (PV) with the densest expression in the pars ventralis portion.{{cite journal|vauthors=Dillingham CM, Holmes JD, Wright NF, Erichsen JT, Aggleton JP, Vann SD| title=Calcium-binding protein immunoreactivity in Gudden's tegmental nuclei and the hippocampal formation: differential co-localization in neurons projecting to the mammillary bodies. | journal=Front Neuroanat | year= 2015 | volume= 9 | pages= 103 | pmid=26300741 | doi=10.3389/fnana.2015.00103 | pmc=4523888 | doi-access=free }} {{cite journal|vauthors=Saunders RC, Vann SD, Aggleton JP| title=Projections from Gudden's tegmental nuclei to the mammillary body region in the cynomolgus monkey (Macaca fascicularis). | journal=J Comp Neurol | year= 2012 | volume= 520 | issue= 6 | pages= 1128–45 | pmid=21830220 | doi=10.1002/cne.22740 | pmc=3909929 }} DTN neurons in rats contain small number of neuropeptide Y positive (NPY) neurons implicating a role in hunger and feeding. In rats, the DTN contains a small number of enkephalin, substance p, and glutamatergic neurons which project to mammillary.{{cite journal|vauthors=Gonzalo-Ruiz A, Romero JC, Sanz JM, Morte L| title=Localization of amino acids, neuropeptides and cholinergic neurotransmitter markers in identified projections from the mesencephalic tegmentum to the mammillary nuclei of the rat. | journal=J Chem Neuroanat | year= 1999 | volume= 16 | issue= 2 | pages= 117–33 | pmid=10223311 | doi= 10.1016/s0891-0618(98)00063-5| s2cid=916774 | url=https://pubmed.ncbi.nlm.nih.gov/10223311 }}

As part of the Papez circuit, the DTN receives input from habenula neurons {{cite journal|vauthors=Herkenham M, Nauta WJ| title=Efferent connections of the habenular nuclei in the rat. | journal=J Comp Neurol | year= 1979 | volume= 187 | issue= 1 | pages= 19–47 | pmid=226566 | doi=10.1002/cne.901870103 | s2cid=25866654 | url=https://pubmed.ncbi.nlm.nih.gov/226566 }} and lateral mammillary neurons.{{cite journal|vauthors=Hayakawa T, Zyo K| title=Quantitative and ultrastructural study of ascending projections to the medial mammillary nucleus in the rat. | journal=Anat Embryol (Berl) | year= 1991 | volume= 184 | issue= 6 | pages= 611–22 | pmid=1776707 | doi= 10.1007/bf00942583| s2cid=7753831 | url=https://pubmed.ncbi.nlm.nih.gov/1776707 }} DTN especially the central part of the DTN receives projections from the G-protein coupled receptor GPR151 containing habenula neurons.{{cite journal|vauthors=Broms J, Antolin-Fontes B, Tingström A, Ibañez-Tallon I| title=Conserved expression of the GPR151 receptor in habenular axonal projections of vertebrates. | journal=J Comp Neurol | year= 2015 | volume= 523 | issue= 3 | pages= 359–80 | pmid=25116430 | doi=10.1002/cne.23664 | pmc=4270839 }}

The pars centralis of the DTN receives input from the prepositus hypoglossi and the supragenualis nucleus.{{cite journal|vauthors=Liu R, Chang L, Wickern G| title=The dorsal tegmental nucleus: an axoplasmic transport study. | journal=Brain Res | year= 1984 | volume= 310 | issue= 1 | pages= 123–32 | pmid=6434154 | doi= 10.1016/0006-8993(84)90015-5| s2cid=21439514 | url=https://pubmed.ncbi.nlm.nih.gov/6434154 }}

Pars ventromedialis of the DTN receives inputs from

• the septal nuclei,
• diagonal band of Broca,
• preoptic area,
• anterior and lateral hypothalamus,
• lateral and medial habenular nuclei,
• medial mammillary nucleus and
• brainstem reticular formation {{cite journal|vauthors=Liu R, Chang L, Wickern G| title=The dorsal tegmental nucleus: an axoplasmic transport study. | journal=Brain Res | year= 1984 | volume= 310 | issue= 1 | pages= 123–32 | pmid=6434154 | doi= 10.1016/0006-8993(84)90015-5| s2cid=21439514 | url=https://pubmed.ncbi.nlm.nih.gov/6434154 }}

Dorsal tegmental fibres project to

• lateral mammillary neurons (LMN) {{cite journal|vauthors=Dillingham CM, Holmes JD, Wright NF, Erichsen JT, Aggleton JP, Vann SD| title=Calcium-binding protein immunoreactivity in Gudden's tegmental nuclei and the hippocampal formation: differential co-localization in neurons projecting to the mammillary bodies. | journal=Front Neuroanat | year= 2015 | volume= 9 | pages= 103 | pmid=26300741 | doi=10.3389/fnana.2015.00103 | pmc=4523888 | doi-access=free }} {{cite journal|vauthors=Allen GV, Hopkins DA| title=Mamillary body in the rat: topography and synaptology of projections from the subicular complex, prefrontal cortex, and midbrain tegmentum. | journal=J Comp Neurol | year= 1989 | volume= 286 | issue= 3 | pages= 311–36 | pmid=2504784 | doi=10.1002/cne.902860303 | s2cid=29423728 | url=https://pubmed.ncbi.nlm.nih.gov/2504784 }} {{cite journal|vauthors=Wirtshafter D, Stratford TR| title=Evidence for GABAergic projections from the tegmental nuclei of Gudden to the mammillary body in the rat. | journal=Brain Res | year= 1993 | volume= 630 | issue= 1–2 | pages= 188–94 | pmid=8118685 | doi= 10.1016/0006-8993(93)90656-8| s2cid=25282593 | url=https://pubmed.ncbi.nlm.nih.gov/8118685 }} {{cite journal|vauthors=Saunders RC, Vann SD, Aggleton JP| title=Projections from Gudden's tegmental nuclei to the mammillary body region in the cynomolgus monkey (Macaca fascicularis). | journal=J Comp Neurol | year= 2012 | volume= 520 | issue= 6 | pages= 1128–45 | pmid=21830220 | doi=10.1002/cne.22740 | pmc=3909929 }}
• dorsal noradrenergic bundle {{cite journal|vauthors=Faiers AA, Mogenson GJ| title=Electrophysiological identification of neurons in locus coeruleus. | journal=Exp Neurol | year= 1976 | volume= 53 | issue= 1 | pages= 254–66 | pmid=964341 | doi= 10.1016/0014-4886(76)90295-8| s2cid=35982595 | url=https://pubmed.ncbi.nlm.nih.gov/964341 }}
• nuclei medialis profundus
• centralis superior,
• the tegmental reticular nucleus,
• the ventral tegmental area of Tsai, and
• the posterior hypothalamic nucleus. The nucleus is a major synaptic station for the pathways of the dorsal longitudinal fasciculus between the diencephalon and lower brain stem {{cite journal| author=MOREST DK| title=Connexions of the dorsal tegmental nucleus in rat and rabbit. | journal=J Anat | year= 1961 | volume= 95 | issue=Pt 2 | pages= 229–46 | pmid=13772534 | pmc=1244467 }}

DTN is a major source of fibers in the mammillary peduncle. Rostral DTN cells that project to the LMN are localized within pars dorsalis and caudal cells that project to the LMN are located in the pars ventralis.

== Function ==

This nucleus is involved in landmark and directional navigation.{{cite journal|vauthors=Clark BJ, Rice JP, Akers KG, Candelaria-Cook FT, Taube JS, Hamilton DA| title=Lesions of the dorsal tegmental nuclei disrupt control of navigation by distal landmarks in cued, directional, and place variants of the Morris water task. | journal=Behav Neurosci | year= 2013 | volume= 127 | issue= 4 | pages= 566–81 | pmid=23731069 | doi=10.1037/a0033087 | pmc=3997071 }} Subpopulations of DTN neurons respond differently to changes in angular head velocity (AHV) and head direction (HD).{{cite journal|vauthors=Bassett JP, Taube JS| title=Neural correlates for angular head velocity in the rat dorsal tegmental nucleus. | journal=J Neurosci | year= 2001 | volume= 21 | issue= 15 | pages= 5740–51 | pmid=11466446 | pmc=6762668 | doi= 10.1523/jneurosci.21-15-05740.2001| doi-access= free }} {{cite journal|vauthors=Sharp PE, Tinkelman A, Cho J| title=Angular velocity and head direction signals recorded from the dorsal tegmental nucleus of gudden in the rat: implications for path integration in the head direction cell circuit. | journal=Behav Neurosci | year= 2001 | volume= 115 | issue= 3 | pages= 571–88 | pmid=11439447 | doi= 10.1037/0735-7044.115.3.571| url=https://pubmed.ncbi.nlm.nih.gov/11439447 }} {{cite journal| author=Taube JS| title=The head direction signal: origins and sensory-motor integration. | journal=Annu Rev Neurosci | year= 2007 | volume= 30 | pages= 181–207 | pmid=17341158 | doi=10.1146/annurev.neuro.29.051605.112854 | url=https://pubmed.ncbi.nlm.nih.gov/17341158 }} {{cite journal|vauthors=Bassett JP, Tullman ML, Taube JS| title=Lesions of the tegmentomammillary circuit in the head direction system disrupt the head direction signal in the anterior thalamus. | journal=J Neurosci | year= 2007 | volume= 27 | issue= 28 | pages= 7564–77 | pmid=17626218 | pmc=6672597|doi=10.1523/JNEUROSCI.0268-07.2007 | doi-access=free }} Some cells respond to changes in head movement in specific directions such as to the left, right, or both. The firing activity of these cells are also affected by the speed of the movement of the head as well. DTN lesions permanently impaired landmark navigation, but only transiently impaired directional navigation.

Category:Brainstem

Category:Neuroanatomy