3.4-3.5 General Principles of Sensory Systems.pdf

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1、3.4-3.5GeneralPrinciplesofSensorySystemsIntroduction1.OverviewofsensoryandmotorsystemsA.neuronalpathways1.seriesofneuronsthattransmitinformationfromonelocation(e.g.,sensorysurface)toadistanttarget(e.g.,cerebralcortex)2.pathwaysmaygoineitherdirection;i.e.,ascendingfromperiphery“

2、inwards”(e.g.,towardscortex;typicalofsensorypathways)ordescendingfromcortex“outwards”(e.g.,towardsspinalcord;typicalofmotorpathways)3.nomenclatureforneuronsinapathwaya.firstorder(primary)neuronsb.secondorder(secondary)neuronsc.thirdorder(tertiary)neuronsB.allmajorsensoryandmoto

3、rpathwayshavemidlinecrossings(=decussations)1.althoughtheevolutionaryperspectiveonpathwaydecussationsremainsopaque,animportantprincipleofbrainfunctionisthateachcerebralhemispherereceivessensoryinformationfromtheoppositesideofthebody2.therefore,eachascending(anddescending)pathwa

4、ymustdecussate交叉成X型3.butstaytuned…inaforthcomingtutorial,youwilllearnthatcerebellarrepresentationisipsilateral!身体同侧的C.sensorytransduction1.sensorytransduction:conversionofthephysical(orchemical)energystimulusintoanelectricalsignalinasensoryneuron2.inthesomaticsensorysystem(seeF

5、igure9.22):A.applicationofastimulusdeformstheskinandthesensoryreceptorsembeddedwithinitB.physicaldeformation(mechanicalforces)ofreceptormembranesopenionschannels,andsodiumions(current)flowsintoreceptorendingPaciniancorpuscle:环层小体C.currentdepolarizesreceptormembraneproducingarec

6、eptor(orgenerator)potentialD.informationcoding1.thequalityofastimulusisencodedbytheidentityoftheactivatedperipheralreceptor(“labeledline”codingscheme)a.differentaxonalendingsrespondtorestrictedsetsofsensorystimulii.selectivityisexplainedby:-morphologicalspecializationsofrecepto

7、rendings-propertiesoftheionotropicchannelsinreceptormembranesii.selectivityisconveyedandpreservedinparallelpathwaysintheCNS分区01.大脑科学的第1页-morphologicalspecializationsofreceptorendings-propertiesoftheionotropicchannelsinreceptormembranesii.selectivityisconveyedandpreservedinparal

8、lelpathwaysintheCNSMeissnercorpuscle:触觉小体Sensitivetoli