3.2-3.3 Overview of Cortex and Cortical Circuits.pdf

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1、3.2-3.3OverviewofCortexandCorticalCircuits2015年5月6日Introduction1.EmbryologicaloriginofthecerebralcortexCortex=Barkthebarkonthetree/theouterrindoftissueA.generationanddifferentiationofneuronsandglia1.nearlyallneuronsaregeneratedbythemiddleofthesecondtrimester;thereafter,onlyveryfewneuronsareeverg

2、eneratedintheCNS!2.neuronalandglialgenesisoccursintheventricularzoneofthedevelopingforebrain:thetelencephalon,whichisderivedfromtheprosencephalon(seeFigure22.32)a.celldivisionoccursagainstthewalloftheventricleswhereprecursorcellsdivideandproduceotherstemcellsformanymitotic有丝分裂cycles(seeFigure22.

3、7)b.somearedestinedtodifferentiateintoaglialprecursorsandothersintoneuronalprecursors,calledneuroblasts神经干细胞Progenitor：祖细胞3.aftermanycyclesofmitoticactivity,somepostmitoticneuroblastsmigrateawayfromtheventricularzonetowardthedevelopingcerebralcortex,calledthecorticalplatea.manyneuronsintheCNSare

4、guidedtofinaldestinationsbyglialcellsthatspanthedistancebetweentheventricularzoneandthepiamaterb.forthedevelopingcorticalplate,neuroblastsmigratealongradialglialcells(seeFigure22.12)4.consequently,thecorticalplatematuresintothecerebralcortexineachhemisphere,whichremainsacontinuous“sheet”ofneural

5、tissuethatbecomesincreasinglyfoldedintotheoutersurfaceoftheforebrain分区02.大脑科学的第1页2.AnatomicalorganizationofthecorticalmicrocircuitA.thecontinuous“sheet”ofneuraltissueineachhemisphereisactuallymulti-layered,withdifferentlayersofneuronsandintrinsicconnectionsservingsomewhatdifferentpurposesB.the“c

6、anonical”corticalmicrocircuit1.thalamusprojectsto(granular)layer4a.called“granular”becauseofthenumeroussmallstellateneuronsthatarefoundinabundanceinthislayer(seeFigure26.2A)b.atlowmagnification,thislayerlookslikegrainsofsand(hencetheterm“granular”)PialsurfaceLayer1:theouterlayer,whichhaswholebun

7、chofaxonsandmyelinatedaxonsLayer4:Thalamicrecipientzone/Granularlayerthetargetoffistorderthalamicnucleithatsendingsignalsintothiscorticalnetwork.IntheNissl,smallercellsLayer5:Pyramidalcells,synapticconnectivity2.layer4projec