Copyofch2Biologyofthemind PDF

Preview

Summary

Download Copyofch2Biologyofthemind PDF

Description

NeuralsandtheHormonalSystem ● ● ● ● ● ● ● ● ●

FranzGall:revealedthatPhrenologys tudyingbumpsontheskullcouldrevealaperson’smental abilitiesandcharactertraits reminderofneedforcriticalthinkingandscientificanalysis focussedattentiononthelocalizationoffunction variousbrainregionshaveparticularfunctions biologicalperspective:linksbetweenbiologyandbehaviour researchersseekingtounderstandthebiologyoftheminddiscoveredthat amongthebody’scellsarenervecellsthattalktooneanotherbysendingchemicalmessengers throughgapthatseparatesthem ouradaptivebrainiswiredbyourexperience weintegrateinformationprocessedinthesedifferentbrainsystemstoconstructourexperienceof sightssoundsmeaningsmemoriespainandpassion

 NeuralCommunication ● humanandanimalsystemsoperatesimilarly ● youcannotdistinguishbetweenbraintissuefromahumanandmonkey ● neurons:nervecells,basicbuildingblockofnervesystem ● neuronsarealldifferentbutareallvariationsofthesametheme ● cellbodyandbranchingfibers ● Dendrite:fibersreceiveinformationandconductittowardthecellbody ● fromtherelengthyaxonfiberpassesthemessagethroughitsterminalbranchestootherneurons ortomusclesorglands ● dendriteslisten,axonsspeak ● dendritescanbeshortwhileaxonsmaybelong ● someaxonsencasedinMyelinSheath ● layeroffattytissuethatinsulatesaxonsandspeedsupimpulsesfromnodetonode ● developstoage25forneuralefficiency,judgement,andselfcontrolgrow ● multiplesclerosisresultsassheathdegrades ● GlialCells:“gluecells”supportnervecells ● cannotsheaththemselves ● providenutrients,insulatemyelin,guideneuralconnectionsandmopupionsand neurotransmitters ● participateintransmissionandmemorythroughchattingwithneurons ● helpwithlearningandthinking ● inmorecomplexbrainstheratioofgliatoneuronsincreases  TheNeuralImpulse ● neuronfiresimpulsecalledactionpotential ● briefelectricchargethattravelsdownitsaxon ● neuronsgenerateenergyfromchemicalevents ● fluidoutsideanaxon’smembranehasmostlypositiveions

● ● ● ● ● ● ● ● ● ● ● ●

axon’sinteriorhasnegativelychargedfluid(potassiumions) abovestatecalledrestingpotential axon’ssurfaceisselectivelypermeable Whenneuronfirestheaxonopensflapgatesandpositivelychargedsodiumionsflowthrough cellmembrane lossofinsideoutsidechargecalledDepolarization causesnextaxonchanneltoopen RefractoryPeriod:restingperiodwhenneuronpumpspositivelychargedsodiumionsback outsidetheaxon sodiumionsrushoutsidethe ifexcitatorysignalsexceedinhibitorysignalsbyaminimumintensitythethresholdwilltrigger anactionpotential increasingthelevelofstimulationabovethethresholdwillnotincreasetheneutralimpulse’s intensity neuron’sreactionisallornoneresponse:theintensityofastimulus strongerstimulustriggersmoreneuronstofirebutdoesnotaffectspeedoftheimpulse

 HowNeuronsCommunicate ● SirCharlesSherrington:noticedthatneuralimpulsesweretakinganunexpectedlylongtimeto traveltoaneuralpathway ● inferredbriefinterruptionintransmission ● meetingpointnamedsynapse ● SantiagoRamonyCajal:marvelledatneuronsmakingprotoplasmickisses ● axonsanddendritesdonttouch ● Neurotransmitters:chemicalmessengersthatcrossthesynapticgapsbetweenneurons ● bindtoreceivingneuronwhereatomsflowinandexciteorinhibitneuron ● excessneurotransmittersdriftawayandbrokendownbyenzymesorreabsorbedbysending neuron:Reuptake  HowNeurotransmittersInfluenceUs ● aparticularbrainpathwaymayuseoneortwoneurotransmitters ● particularneurotransmittersmayaffectspecificbehavioursandemotions ● neurotransmittersinteractandtheireffectsvaryonthereceptorstheystimulate ● Acetylcholinep laysaroleinlearningandmemory ● makesourmusclescontractwhenreleasedtomusclecellreceptors ● CandacePertandSolomonSnydermadeanexcitingdiscoverywhentheyattacheda radioactivetracertomorphineandobservedwhereitwastakenupinananimal’sbrain ● morphineisanopiatedrugthatelevatesmoodandeasespain ● boundtoreceptorslinkedtomoodandpainsensations ● brainproducesitsownnaturallyoccurringopiates ● ourbodyreleasesseveraltypesofneurotransmittermoleculessimilartomorphine ● Endorphinsexplaingoodfeelingslikerunner’shighorindifferencetopaininseverelyinjured people

● ● ● ● ● ● ● ●

whenfloodedwithopiatedrugssuchasheroinandmorphinethebrainmightstopproducing naturalopiates whenthebrainbecomesdeprivedoftheopiatedrugsdiscomfortresults Agonist:Moleculesthatincreaseaneurotransmitter’saction mayincreasetheproductionorreleaseofneurotransmittersorblockreuptakeinasynapse otheragonistsmaybesimilarandbindtoneurotransmittersmimicingtheinhiborexhibaffects otheragonistsprovideatemporaryhighandamplifynormalsensationsthrougharousalor pleasure Antagonists:decreaseaneurotransmitter’sactionbyblockingproductionorrelease botulinisusedinbotoxbuthighamountscancauseparalyzation

 TheNervousSystem ● Thebody’selectrochemicalcommunicationnetworkconsistingofallthenervecellsofthe peripheralandcentralnervoussystems ● Nerves:bundledaxonsthatformneuralcablesconnectingthecentralnervoussystemwith muscles,glandsandsenseorgans ● Sensoryneurons:carrymessagesfromthebody’stissuesandsensoryreceptorsinwardtothe brainandspinalcordAfferent ● MotorNeurons:carrymessagesfromCNStobody’smusclesandglands ● Betweensensoryandmotoroutput,infoisprocessedviainterneurons  ThePeripheralNervousSystem ● Somaticnervoussystem:enablesvoluntarycontrolofourskeletalmuscles ● autonomicnervoussystem:controlsourglandsandinternalorganmuscles ● influencesglandularactivity,heartbeatanddigestion ● ServesSympatheticNervousSystem:arousesandexpandsenergy ● fastenedheartbeat,sweat,raisedbloodpressure ● ParasympatheticNervousSystem:Whenstressisover,willconserveenergyandcalmyou ● bothsystemsworktogethertokeephomeostasis  TheCentralNervousSystem ● thebrain’sneuronclustersworktogetherinneuronclusters ● neuronsthatfiretogetherwiretogether ● thespinalcordisatwowayinformationhighwaythatconnectstheperipheralnervoussystemand thebrain ● ascendingneuronfiberssendupinfotobrainandbrainsendsbackdescendinginformationback asmotorcontrolinformation ● theneuralpathwaysgovernourreflexes(automaticresponsetostimuli) ● asimplespinalreflexpathwayiscomposedofasensoryneuronandamotorneuronthatoften communicatethroughtheinterneuron  TheEndocrineSystem ● glandssecreteaformofchemicalmessengers

● ● ● ● ● ● ● ● ● ● ● ● ● ●

hormones:chemicalmessengersthattravelthroughthebloodstreamandaffectothertissues bothendocrineandnervoussystemsproducechemicalsthatactonreceptorselsewhere endocrinemessagesoutlastnervouseffectsofneuralmessages InamomentofdangertheANSsystemtriggerstheadrenalglandsadrenalineornoradrenaline increaseheartrate,bloodpressureandbloodsugar PituitaryGland:Peasizedstructurelocatedincoreofbrain controlledbyhypothalamus releasesgrowthhormoneandoxytocin Pituitaryglandsalsoenableendocrineglandstoreleasehormones masterofthehypothalamus eg:triggersbraintoreleasesexhormonesthatinfluencebrainandbehaviour stressfuleventcauseshypothalamustoinstructpituitaryglandtoreleasecortisolfromtheadrenal glands? Brain→Pituitary→otherglands→Hormones→bodyandbrain nervoussystemdirectsendocrinesystemtosecretematerialthataffectsnervoussystem

 

ToolsofDiscoveryandOlderBrainStructures ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Brain+body=Mind scientistscanselectivelylesiontinyclustersofbraincellsleavingthesurroundingtissue unharmed microelectrodescannowdetectexactlywheretheinformationgoesinacat’sbrain Electroencephalogram(EEG)isanamplifiedreadoutofneuronwavesthatsweepthebrain’s surface stimulusisshownandbrainactivityisrecorded PET(Positionemissiontomography)scan:depictsbrainactivitybyshowingeachbrainarea’s consumptionofitschemicalfuel,glucose ourbrainconsumes20%ofourcalorieintake MRI(Magneticresonanceimaging)brainscanstheperson’sheadisputinastrongmagnetic field,whichalignsthespinningatomsofbrainmolecules radiowavethenmomentarilydisorientsatoms whenatomsreturntonormalspintheyemitsignalsthatprovidedetailedpictureofsofttissue fMRI:canrevealthebrain’sfunctioningaswellasitsstructures wherethebrainisespeciallyactive,bloodgoes inprimitiveanimalstheprimaryregulatesbasicsurvivalfunctions:breathing,restingandfeeding lowermammalsbrainamorecomplexbrainenablesemotionandgreatermemory inadvancedmammalsabrainthatprocessesmoreinformationenablesincreasedforesightaswell arisesfromnewbrainsystemsbuiltonold

 TheBrainstem ● Thebrain’soldestandinnermostregion ● beginswherespinalcordswellsafterenteringtheskull

● ● ● ●

Medulla:theslightswellingthatcontrolsbreathingandheartbeat justabovethemedullasitsthepons helpcoordinatemovementsandcontrolsleep thebrainstemisacrossoverpointwheremostnervestoandfromeachsideofthebrainconnect withthebody’soppositeside

 TheThalamus ● sitsatopofthebrainstem ● pairofeggshapedstructuresthatactasthebrain’ssensorycontrolcenter ● receivesinformationfromallsensesexceptsmellandroutesittohigherbrainregionsthatdeal withseeing,hearing,smelling,touching ● alsoreceiveshigherbrainrepliesthatitdirectstothemedullaandcerebellum ● hubthroughwhichtrafficpowers  TheReticularFormation ● inthebrainstembehindyourears ● neuronnetworkextendingfromspinalcordrightupthroughthalamus ● filtersincomingstimuli,relaysimportantinformationtootherbrainareasandcontrolsarousal ● 1949GiuseppeMoruzziandHoraceMagoundiscoveredthatelectricallystimulatingasleeping cat’sreticularformationalmostinstantlyproducedawake  TheCerebellum ● extendingfromtherearofthebrainstembaseballsized ● involvedinmotormovementwiththebasalganglia ● enablesnonverballearningandskillmemory ● helpsusjudgetime,modulateouremotionsanddiscriminatesoundsandtextures ● withhelpofPonscoordinatesvoluntarymovement ● ifyouinjuredyourcerebellumyou’dhavedifficultywalking,keepingbalanceorshakinghands ● alloccurwithoutanyconsciousbraineffort  TheLimbicSystem ● brain’snewestandhighestregionscalledcerebralhemispheres ● limbicsystemliesbetweennewandoldareasofthebrain ● containstheamygdala,hypothalamusandhippocampus ● Hippocampus:processesconscious,explicitmemories ● animalsthatlosethehippocampusduetosurgerylosetheirabilitytoformnewmemoriesoffacts andevents ● linkstoemotionsfoodangerandarousal ● Amygdala:twolimabeansizedneuralclustersthat ● linkedtoaggressionandfear ● HeinrichKluverandPaulBucysurgicallyremovedarhesusmonkey’samygdalaturningthe mostilltemperedanimaltoamellowcreature

● ● ● ● ● ● ● ● ● ●

thosewithlesionamygdalalesionsoftendisplayreducedarousaltofearandangerarousing stimuli Hypothalamus:importantlinkinthecommandchaingoverningbodilymaintenance someneuralclustersinfluencehunger,othersregulatethirst,bodytempandsecualbehaviour monitorsyourstateofbody picksupsignalsfrombrain’scortexesandthensecreteshormonesthattriggerpituitaryglandto secretehormonesthatinfluenceglands otherlimbicrewardcentersnucleusaccumbensi nfrontofthehypothalamus researchrevealsthatstimulatingthebrain’shedonichotspotsp roducemoredesirethanenjoyment dopaminereleaseenablesustoget“chills’whenwehearasongwelike addictivedisordersmaystemfrombrainmalfunctions peoplepredisposedtorewarddeficiencysyndromemaycravewhateverpossibletoprovide missingpleasureorrelievenegativefeelings



TheCerebralCortexandDividedBrain ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

newernetworksofourbrainwithinthecerebrumenableperceiving,thinkingandspeaking CerebralCortex:athinsurfacelayerofinterconnectedneuralcells brain’sthinkingcrownandbody’sultimatecontrolandinformationprocessor largerthecortexthemorefunctionsandabilitiestheanimalshave thebrain’sleftandrighthemispheresaremainlyfilledwithaxonsconnectingthecortextothe brain’sotherregions eachcerebralcortexissubdividedintofourlobes: Frontallobe:liesjustbehindtheforeheadinvolvedinspeaking,musclemovements,making plansandjudgement ParietalLobes:Topofheadtowardsrearthatreceivessensoryinputfortouchandbodyposition Occipitallobes:atbackofheadthatreceiveinfofromvisionaryfields Temporallobes:lyingabovetheearsthatincludesauditoryareas,eachreceivesinformation fromtheoppositeear Motorcortex:areaatrearoffrontallobesthatcontrolsvoluntarymovements GustavFritschandEduardHitzigdiscoveredthatmildstimulationstopartsofananimal’s cortexmadepartsofitsbodymove discoveredthemotorcortex thebrainhasnosensoryreceptors OtfridFoersterandWilderPenfieldmappedthemotorcortexsofwideawakepatientsand observedresponsesbystimulatingdifferentcorticalareas discoveredthatthebodyareasrequiringprecisecontroloccupythegreatestamountofcortical space JoseDelgadostimulatedaspotofhispatient’sleftmotorcortextofindtherighthandstimulated

 SensoryFunctions ● Penfielddiscoveredacorticalareaatthefrontofparietallobesparalleltoandjustbehindthe motorcortex

● ● ● ● ● ● ● ● ● ●

Somatosensorycortex:specializesinreceivingareainformationfrominfofromskinsensesand movementfrombodyparts themoresensitivethebodyregion,thelargerthesomatosensorycortexareadevotedtoit prefrontalcortexenablesjudgement,planning,andprocessingofnewmemories peoplewithdamagedfrontallobeshavehighintelligencebutarenotabletoplanahead frontallobedamagecanalsoaffectone’spersonalityandinhibitions moraljudgementsareunrestrainedbynormalemotions undersideofrighttemporallobeallowsustorecognizefaces damageofthisareacausesyoutostillretainmemoriesofone’sfeaturesbutnotidentifythem personally complexmentalfunctionsdonotresideinoneplace memorylanguageandattentionresideresultfromsynchronizedactivityfromdistinctbrainareas andneuralnetworks

 Handedness ● almostallrighthandersspeechprimarilyinthelefthemisphere ● lefthandersaremorediverse ● genesorsomeparietalfactorsaffecthandedness ● lefthandersaremorenumerousthanusualamongthosewithreadingdisabilities,allergiesand migraineheadaches ● lefthandedinmusiciansand,mathematics,professionalbaseballandcricket,architectsand artists.  ChapterSummary ● everythingpsychologicalissimultaneouslybiological      ...