Know Your Brain: Diencephalon - Neuroscientifically ...

The diencephalon is a small part of the brain that is mostly hidden from view when you are looking at the outside of the brain. NEUROSCIENTIFICALLYCHALLENGEDNEUROSCIENCEMADESIMPLERSubscribeKnowYourBrain:DiencephalonWhereisthediencephalon?Thediencephalonisasmallpartofthebrainthatismostlyhiddenfromviewwhenyouarelookingattheoutsideofthebrain.Itisdividedintofourparts:theepithalamus,thalamus,subthalamus,andhypothalamus.Thediencephaloncanbefoundjustabovethebrainstembetweenthecerebralhemispheres;itformsthewallsofthethirdventricle. Theonlypartofthediencephalonthatcanbeseenwithouttakingacross-sectionofthebrainisthebottom-mostportionofthehypothalamus.Whatisthediencephalonandwhatdoesitdo?Despitebeingarelativelysmallpartofthecentralnervoussystemintermsofmass,thediencephalonplaysanumberofcriticalrolesinhealthybrainandbodilyfunction.Becauseitconsistsofacollectionofstructures,though,itwouldnotmakesensetotrytodefinethefunctionsofthediencephalonwithonesummary.Instead,I'llbrieflytouchontherolesofeachofitssub-components,althoughit'simportanttorealizethateventhesesummarieswill(bynecessity) besimplified.EpithalamusTheepithalamuscircledinred.Theepithalamusconsistsprimarilyofthepinealglandandthehabenulae.Thepinealglandisanendocrineglandthatsecretesthehormonemelatonin,whichisthoughttoplayanimportantroleintheregulationofcircadianrhythms.Tolearnmoreaboutthepinealgland,readthisKnowYourBrainarticle.Thehabenulae(moreoftenreferredtowiththesingular:habenula)aretwosmallareasnearthepinealgland.Thefunctionsofthehabenulaarepoorlyunderstood,butitisthoughttopotentiallybeinvolvedwithrewardprocessingandhasbeenimplicatedindepression.Additionally,thereissomeevidencethatthehabenulaalsoproducesmelatonin,andthatitmightbeinvolvedwithsleepregulation.Tolearnmoreaboutthehabenula,readthisKnowYourBrainarticle.SubthalamusApproximateareaofthesubthalamuscircledinred.Aportionofthesubthalamusismadeupoftissuefromthemidbrainextendingintothediencephalon.Thus,partsofmidbrainregionslikethesubstantianigraandrednucleusarefoundinthediencephalon.Thesubthalamusisalsohometothesubthalamicnucleusandthezonaincerta.Thesubthalamicnucleusisdenselyinterconnectedwiththebasalganglia,andplaysaroleinmodulatingmovement.Thezonaincertahasmanyconnectionsthroughoutthecortexandspinalcord,butitsfunctionisstillnotdetermined. Severalcollectionsofimportantfibers(e.g.somatosensoryfibers)alsopassthroughthesubthalamus.ThalamusThethalamusiscoloredinred.Therearetwoofthesestructures(side-by-side)inanintactbrain.Thethalami(morefrequentlyreferredtowiththesingular: thalamus) consistoftwoovalcollectionsofnucleithatmakeupmostofthemassofthediencephalon.Thethalamusisoftendescribedasarelaystationbecausealmostallsensoryinformation(withtheexceptionofsmell)thatproceedstothecortexfirststopsinthethalamusbeforebeingsentontoitsdestination.Thestructureissubdividedintoanumberofnucleithatpossessfunctionalspecializationsfordealingwithparticulartypesofinformation.Sensoryinformationthustravelstothethalamusandisroutedtoanucleustailoredtodealingwiththattypeofsensorydata.Then,theinformationissentfromthatnucleustotheappropriateareainthecortexwhereitisfurtherprocessed.Thethalamusdoesn'tdealjustwithsensoryinformation,however.Italsoreceivesagreatdealofinformationfromthecerebralcortex,anditisinvolvedwithprocessingthatinformationandsendingitbacktootherareasofthebrain.Duetoitsinvolvementinthesecomplexnetworks,thethalamusplaysaroleinanumberofimportantfunctionsrangingfromsleeptoconsciousness.Tolearnmoreaboutthethalamus,readthisKnowYourBrainarticle. HypothalamusHypothalamuscoloredinred.Thehypothalamusisasmall(aboutthesizeofanalmond)regionlocateddirectlyabovethebrainstem. Italsoismadeupofacollectionofnucleithatareinvolvedinavarietyoffunctions.Thehypothalamusisoftenlinked,however,totwomainroles:maintaininghomeostasisandregulatinghormonerelease.Homeostasisisthemaintenanceofequilibriuminasystemlikethehumanbody.Optimalbiologicalfunctionisfacilitatedbykeepingthingslikebodytemperature,bloodpressure,andcaloricintake/expenditureatafairlyconstantlevel.Thehypothalamusreceivesasteadystreamofinformationaboutthesetypesoffactors.Whenitrecognizesanunanticipatedimbalance,itenactsamechanismtorectifythatdisparity.Thehypothalamusactstomaintainhomeostasis---andinfluencesbehavioringeneral---byregulatinghormonesecretion.Thisisprimarilydonethroughthecontrolofhormonereleasefromthepituitarygland.Throughthismechanism,thehypothalamushaswidespreadeffectsonthebodyandbehavior. ItisoftensaidthatthehypothalamusisresponsibleforthefourFs:fighting,fleeing,feeding,andfornication.Clearly,duetothefrequencyandsignificanceofthesebehaviors,thehypothalamusisextremelyimportantineverydaylife.Tolearnmoreaboutthehypothalamus,readthisKnowYourBrainarticle.References:VanderahTW,GouldDJ.Nolte'sTheHumanBrain.7thed.Philadelphia,PA:Elsevier;2016.ReceiveNewContentbyEmail:OrderNowYOURBRAIN,EXPLAINEDSleep.Memory.Pleasure.Fear.Language.Weexperiencethesethingseveryday,buthowdoourbrainscreatethem?YourBrain,Explainedisapersonaltouraroundyourgraymatter.BuildingonneuroscientistMarcDingman’spopularYouTubeseries,2-MinuteNeuroscience,thisisafriendly,engagingintroductiontothehumanbrainanditsquirksusingreal-lifeexamplesandDingman’sown,hand-drawnillustrations.PreviousSlideNextSlideReadinglikeacollectionofdetectivestories,YourBrain,Explainedcombinesclassiccasesinthehistoryofneurologywithfindingsstemmingfromthelatesttechniquesusedtoprobethebrain’ssecrets.-StanleyFinger,PhD,ProfessorEmeritusofPsychological&BrainSciences,WashingtonUniversity(St.Louis),author,OriginsofNeuroscienceDingmanweavesclassicstudieswithmodernresearchintoeasilydigestiblesections,toprovideanexcellentprimerontherapidlyadvancingfieldofneuroscience.-MohebCostandi,author,Neuroplasticityand50HumanBrainIdeasYouReallyNeedtoKnow...ahighlyreadableandaccessibleintroductiontotheoperationofthebrainandcurrentissuesinneuroscience...awonderfulintroductiontothefield.-FrankAmthor,PhD,ProfessorofPsychology,TheUniversityofAlabamaatBirmingham,author,NeuroscienceforDummiesAninformative,accessibleandengagingbookforanyonewhohaseventheslightestinterestinhowthebrainworks,butdoesn’tknowwheretobegin.-DeanBurnett,PhD,author,HappyBrainandIdiotBrainOrderNow