A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, ...BrainFromWikipedia,thefreeencyclopediaJumptonavigationJumptosearchOrganthatcontrolsthenervoussysteminvertebratesandmostinvertebratesThisarticleisaboutthebrainsofalltypesofanimals,includinghumans.Forinformationspecifictothehumanbrain,seeHumanbrain.Forotheruses,seeBrain(disambiguation)andBrains(disambiguation).BrainAcommonchimpanzeebrainIdentifiersMeSHD001921NeuroNames21TA98A14.1.03.001TA25415Anatomicalterminology[editonWikidata]Abrainisanorganthatservesasthecenterofthenervoussysteminallvertebrateandmostinvertebrateanimals.Itislocatedinthehead,usuallyclosetothesensoryorgansforsensessuchasvision.Itisthemostcomplexorganinavertebrate'sbody.Inahuman,thecerebralcortexcontainsapproximately14–16billionneurons,[1]andtheestimatednumberofneuronsinthecerebellumis55–70billion.[2]Eachneuronisconnectedbysynapsestoseveralthousandotherneurons.Theseneuronstypicallycommunicatewithoneanotherbymeansoflongfiberscalledaxons,whichcarrytrainsofsignalpulsescalledactionpotentialstodistantpartsofthebrainorbodytargetingspecificrecipientcells.Physiologically,brainsexertcentralizedcontroloverabody'sotherorgans.Theyactontherestofthebodybothbygeneratingpatternsofmuscleactivityandbydrivingthesecretionofchemicalscalledhormones.Thiscentralizedcontrolallowsrapidandcoordinatedresponsestochangesintheenvironment.Somebasictypesofresponsivenesssuchasreflexescanbemediatedbythespinalcordorperipheralganglia,butsophisticatedpurposefulcontrolofbehaviorbasedoncomplexsensoryinputrequirestheinformationintegratingcapabilitiesofacentralizedbrain.Theoperationsofindividualbraincellsarenowunderstoodinconsiderabledetailbutthewaytheycooperateinensemblesofmillionsisyettobesolved.[3]Recentmodelsinmodernneurosciencetreatthebrainasabiologicalcomputer,verydifferentinmechanismfromanelectroniccomputer,butsimilarinthesensethatitacquiresinformationfromthesurroundingworld,storesit,andproc