{{Short description|Region of the brain}} {{Infobox brain | Name = Interpeduncular nucleus | Latin = nucleus interpeduncularis | IsPartOf = | Components = Apical subnucleus (IPA), Central subnucleus (IPC), Dorsolateral subnucleus (IPDL)x2, Dorsomedial subnucleus (IPDM)x2, Intermediate subnucleus (IPI)x2, Lateral subnucleus (IPL)x2, Rostral subnucleus (IPR) | Artery = | Vein = }} The '''interpeduncular nucleus''' ('''IPN''') is an unpaired, ovoid group of neurons at the base of the midbrain tegmentum. In the midbrain it lies below the interpeduncular fossa. As the name suggests, the interpeduncular nucleus lies ''in between'' the cerebral peduncles.
==Composition== The Interpeduncular nucleus is primarily GABAergic and contains at least two neuron clusters of different morphologies.<ref name="Gioia">{{citation| author=Gioia, Magda |title=A cluster analysis of the neurons of the rat interpeduncular nucleus |journal=Journal of Anatomy |location=University of Milan, Italy |publisher=Wiley-Blackwell |year=1994|volume=185 ( Pt 3) |issue=Pt 3 |pages=459–464 |pmid=7649781 |pmc=1166650 }}</ref> The region is divided into 7 paired and unpaired subnuclei
===Subdivisions=== The presence of non-homologous subdivisions of the Interpeduncular nucleus was first noticed by Cajal over a hundred years ago.<ref>{{cite book|last=Ramón y Cajal|first=Santiago|title=Histologie du Système Nerveux de l'Homme et des Vertébrés, L. Azoulay, trans. Paris: Maloine. Translated into English as Histology of the Nervous System of Man and Vertebrates (1995)|publisher=Oxford University Press|year=1909|location=New York}}</ref> The currently recognized standard subdivision notation was mostly established by Hammill and Lenn in 1984 by combining the work and notations of four groups.<ref name="lenn">{{cite journal|last=Lenn|first=NJ|author2=Hamill, GS|title=Subdivisions of the interpeduncular nucleus: a proposed nomenclature.|journal=Brain Research Bulletin|date=July 1984|volume=13|issue=1|pages=203–4|pmid=6478267|doi=10.1016/0361-9230(84)90023-6}}</ref> Although most of their proposed convention stuck, at some point the proposed "rostral lateral" sub-nucleus was renamed "dorsomedial" and became immortalized in brain atlases. * '''Apical sub-nucleus (IPA)''' Unpaired sub-nucleus. Former names include: "caudal dorsal", "dorsal", and "pars dorsalis magnocellularis".<ref name="lenn" /> * '''Central sub-nucleus (IPC)''' Unpaired sub-nucleus. Former names include: "rostral ventral", "caudal central", "posterior inter", and "pars medianus".<ref name="lenn" /> * '''Dorsolateral sub-nucleus (IPDL)''' Paired sub-nucleus. * '''Dorsomedial sub-nucleus (IPDM)''' Paired sub-nucleus. Former names include: "rostral lateral" and "interstitial".<ref name="lenn" /> * '''Intermediate sub-nucleus (IPI)''' Paired sub-nucleus. Former names include: "caudal intermediate", "posterior inner" and "pars medianus".<ref name="lenn" /> * '''Lateral sub-nucleus (IPL)''' Paired sub-nucleus. Former names include: "caudal lateral", "paramedian" and "pars lateralis".<ref name="lenn" /> * '''Rostral sub-nucleus (IPR)''' Unpaired sub-nucleus. Former names include: "central" and "pars dorsalis".<ref name="lenn" />
==Inputs== The major input to the IPN arrives via the fasciculus retroflex from the medial habenula. This pathway presents the IPN with several excitatory neurotransmitters including ACh and Substance P. Other brain regions that project to the Interpeduncular nucleus include: the Nucleus of diagonal band, the dorsal Tegmentum, the Raphe nuclei, the Central grey, and the Locus coeruleus.<ref name=morley>{{cite book|last=Morley|first=BJ|chapter=The Interpeduncular Nucleus |title=International Review of Neurobiology Volume 28|year=1986|volume=28|pages=157–82|pmid=2433243|doi=10.1016/s0074-7742(08)60108-7|isbn=9780123668288}}</ref>
==Outputs== The major output pathways are inhibitory and project to the dorsal Tegmental area, the Periaqueductal gray and also the Raphe nuclei. In addition, output is sent to the following: the mediodorsal nucleus of the Thalamus, the lateral Habenula, the Septal nuclei, the anterior Mammillary nuclei, the Nucleus of diagonal band, the Preoptic area, the Ventral tegmental area, and in some species the dorsal and/or lateral Hypothalamus.<ref name="morley" />
==Function== The Interpeduncular nucleus is thought to have a broad inhibitory effects on many other brain regions. IPN activity is linked with decreased dopamine release and utilization from dopamine producing regions.<ref>{{cite journal|last=Nishikawa|first=T|author2=Fage, D |author3=Scatton, B |title=Evidence for, and nature of, the tonic inhibitory influence of habenulointerpeduncular pathways upon cerebral dopaminergic transmission in the rat.|journal=Brain Research|date=May 14, 1986|volume=373|issue=1–2|pages=324–36|pmid=2424555|doi=10.1016/0006-8993(86)90347-1}}</ref> The Interpeduncular nucleus is implicated with a role in the regulation of Rapid eye movement sleep.<ref name="Funato">{{citation| author=Funato, Hiromasa |title=Loss of Goosecoid-like and DiGeorge syndrome critical region 14 in interpeduncular nucleus results in altered regulation of rapid eye movement sleep |location=University of Texas Southwestern Medical Center, Dallas |publisher=PNAS |year=2010}}</ref> Activation of the GAD2 expressing sub-population of the IPN produced the physical symptoms of nicotine withdrawal suggesting that the misfunction of this region may be an active component of withdrawal.<ref>{{cite journal|last=Zhao-Shea|first=R|author2=Liu, L |author3=Pang, X |author4=Gardner, PD |author5= Tapper, AR |title=Activation of GABAergic Neurons in the Interpeduncular Nucleus Triggers Physical Nicotine Withdrawal Symptoms.|journal=Current Biology|date=Nov 13, 2013|pmid=24239118 |doi=10.1016/j.cub.2013.09.041 |volume=23 |issue=23 |pages=2327–35 |pmc=3855889|bibcode=2013CBio...23.2327Z}}</ref>
==See also== * Regions in the human brain
==References== {{Reflist}}
==External links== * [http://www.mondofacto.com/facts/dictionary?interpeduncular+nucleus Dictionary definition from Mondofacto.com]
{{Mesencephalon}} {{Authority control}}
Category:Midbrain Category:Brainstem nuclei