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Download Heading: Sensory Deprivation in Humans, Mice, and History Caleb B. Carson Running Head: Sensory Deprivation
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Running Head: Sensory Deprivation 1 Heading:SensoryDeprivationinHumans,Mice,andHistory CalebB.Carson Running Head: Sensory Deprivation 2 Abstract Thispaperwillhighlightastudydoneinlabmice,toobservetheeffectsofsensory deprivationonspinaldendrites.Lightwillbegiventothehistoryofsensorydeprivation chambers,focusingonJohnC.Lillyandhiswork,aswellashisfindingsintheeffectsof thesechambersonpeople.Thewriter’sowntheorywillbeproposed,basedoffofan analyzedcasestudy,centeredaroundthehearinglossofanolderwoman.Thiscasestudy involvestheobservationandtreatmentofawomanwhoclaimedtohearvoicesafter hearinglossduetoacaraccident.Timeisgiventodefiningtheuseandstructureof vibrissae,inordertohighlighttheirimportanceinthespinaldendritestudy. Running Head: Sensory Deprivation 3 HistoryofSensoryDeprivationChambers Littlewasdoneinthestudyofsensorydeprivation,throughthemeansofactual testsinhumansubjects,untilameansinwhichtotestpeople,andtheories,wasdeveloped byJohnCLilly.Foralongtime,peopletheorisedoutlandishpossibilitiesofwhatwould happenwhensomeonewasdeprivedofnearlyalltheirsenses.Somebelievedyoucould contactotherworlds,whilemoregroundedthinkersassumedyouwouldsimplybeputinto ahigherstateofconcentration,abletotheorize,think,andpondermoreefficiently.Many peopleweretested,andwhilefewspokeoftravelingtootherworlds,moststated experiencingwhatmanyknowasan,“outofbodyexperience”.Feelingdisconnectedfrom theirbodiesduetoanabsenceofsensoryinputtoletthebrainknowweareevenstillalive, webegintofeeldetached.StudiesdonebyLillyresultedinfindingsthatshowedjust15 minutesofnear-totalsensorydeprivationwasenoughtotriggervividhallucinationsin manyofitstestsubjects. "Somewhere,deepwithinthebrain,wasamechanismcapableofgeneratinginternal experiencescompletelyindependentoftheoutsideworld,andthissettledtheissueofwhat happensinprofoundphysicalisolation.Theminddoesnotpassintounconsciousness,the braindoesnotshutdown.Instead,itconstructsexperienceoutofstoredimpressionsand memories.Theisolatedmindbecomeshighlyactiveandcreative.Thiswastheprincipal discoverythatDr.Lillyreportedinhisfirstthreescientificpapersontheisolationtank research,publishedin1956,1957,and1958." . Running Head: Sensory Deprivation 4 DefiningSensorydeprivation Itisnecessary,thatwhendiscussingorreadingatopicofinterest,apersonshould beginwithabasicandconcreteunderstandingregardingthefoundationsofthesubject matter.SensorydeprivationisdefinedbyDictionairy.comas,“Theexperimentalornatural reductionofenvironmentalstimuli,asbyphysicalisolationorlossofeyesight,often leadingtocognitive,perceptual,orbehavioralchanges,asdisorientation,delusions,or panic.”Thisdefinitionwouldnotbefoundtobeallinclusive,however,onewoulddowell touseitasacornerstonefromwhichtobuildoff.Firstly,whenreconstructingthis definitionforpurposesofapplication,Iwouldliketostartoffontheabsenceofrecognition inregardstoauditorydeprivation.Inthispaperyouwilllearnaboutawomanwho experiencedsomeeffectsofwhatispresumedtobesensorydeprivation,duetothelossof herhearing. Followingthissamepathofdefinitoryreasoning,theothersensesneedtobe includedinafullyworkingdefinitionaswell,asthisis“sensory”deprivation;sensorybeing anallinclusiveword.Inastudythatwillbeincludedinthispaper,andwillcomprisean extensiveamountofthiswriting,micewereforcedintoaformofsensorydeprivationby theremovingoftheirwhiskersor,“feelers.”Withthisinmind,thedefinitionshouldalsobe suretoinclude,whetherdirectlyorindirectly,thelossoftactilesensory. TheVibrissae Theaforementionedwhiskersarealsoknownas“vibrissae”,andareatypeof mammalianhairthataretypicallycharacterisedanatomically,bytheirlargesize,asawell- Running Head: Sensory Deprivation 5 innervatedhairfollicle,andbyhavinganidentifiablerepresentationinthesomatosensory cortexofthebrain. Theyarespecializedfortactilesensingactingmuchlikeskinorfeelers.What howevermakesthemdifferentfromotherhairsandaretheydifferentatall?Thereare numerousdifferences.Thevibrissalhairisusuallythickerandstifferthanothertypesof pelagichair,but,likeotherhairs,theshaftconsistsofaninertmaterialcalledkeratin,and containsnonerves.Contrastly,ifthesevibrissaehavenonerves,howcantheybeusedfor tactilesensory?Theansweristhattheygrowfromaspecialhairfollicle,incorporatinga capsuleofbloodcalleda“bloodsinus,”whichisheavilyinnervatedbysensorynerves. VibrissaeinApplicationStudies. Nowthatweknowtheirfunction,letuslookatwhythesewhiskersaresopivotal.It isfoundthatratsandmicehaveapproximately30macrovibrissaeoneachsideoftheface, withwhiskerlengthsuptoaround50mminlaboratoryrats,30mminlaboratorymice. Thus,anestimateforthetotalnumberofsensorynervecellsservingthemystacialvibrissal arrayonthefaceofaratormousemightbe25,000.Thisnumberinrelationtothenumber ofsensoryneuronsinthebodyofamouseorratisastonishing.Inordertobetter understandtheextentofthedeprivationthemicewereputunder,youcanimaginethisas theequivalenttocuttingoffbothofyourhands.Nowwithamorecomprehensiveand operationalunderstandingofthepremiseoftheresearchportrayedthroughthismedium ofwriting,wewillbeginlookingdeeperintosensorydeprivationinlabratsandmice,and eventually,inpeople. Running Head: Sensory Deprivation 6 PreventionofDendriticSpineLossinMiceviaSensoryDeprivation Tobegin,anunderstandingmustbehadofthespinaldendrite,andtherebytheloss ofsynapsesthatisexperiencedbymiceastheyage.Experienceplaysakeyroleinthe modificationofsynapticactivity,however,itisnotcurrentlyunderstoodhowitrelatesto thenearlylifelongsynapselossinmice(thecontinuedlossofsynapsesoccurringnaturally throughouttheagingprocess.).Whatisknownforsurebyscientistshowever,isthat synapticlossisapparentthroughoutthelifeoflaboratorymice.Ithasbeendiscoveredthat sensorydeprivationthroughthemediumofwhiskertrimming,decreasesthenumberof synapseslostthroughoutthelifeofthemouse,aninquisitiveandseeminglycontradictory discovery. Thetypicalpercentageofspinalsynapseslostinhumansandmostmammalsison average50%,andtakesplacethroughouttheentirelifespanoftheanimal,primaryinthe adolescentstages.Whenthevibrissaearetrimmed,causingnearcompletetactilesense deprivation,thelossofsynapsesisgreatlydecreased,almosttoastop.However,ifamouse isputthroughadolescenceinadeprivedstate,andthenhasitssensesrestoredin adulthood,thesynapticlossisspedupincredibly.Thisindicatesthattheroleofexperience insynapselossisoneofimportance,butnotyetclearlydefined.Itisalsofoundthat Piaget'sideaoflearningreboundisfoundtobepresent,andseeminglyrelatedtothe occurrenceofarapidlossindendriticspines,soonaftersensoryrecover. Running Head: Sensory Deprivation 7 ExperimentResultsandFindings Itisfoundintheexperiment,Long-termsensorydeprivationpreventsdendriticspine lossinprimarysomatosensorycortex,incontrolmiceonemonthofage,thatthenumberof spineseliminatedoveratwoweekperiodwassignificantlyhigherthanthepercentage formed.Todeterminetheeffectsofthesensorydeprivationonthisspinaldendriteloss rate,micefromfourweeksofagetosixweeksofagehadtheirwhiskerstrimmedonone sideofthefacialpad.Thenumberofspinesgeneratedandeliminatedcomparedtothe “non-deprivedconstantgrowthvs,non-depriveddendritelossratio”,wasfardifferent;not speedingupthegrowth,butsimplyslowingtheloss.Therewasnosignificantchangeinthe numberofspinesformed.Asmentionedpreviously,onceadulthoodisreached,(whichin thiscaseisdefinedas4monthsandbeyond),thelossofdendriticspinesissignificantly reduced.However,whentestsonadultswentfromonlytwoweekswithlittleresultsand werebumpedupto2months,asignificantreductioninspinereductionwasfound. Todeterminewhetherspinelosswouldreboundafterreintroductiontotactile sensory,whiskersoftwomontholdmiceweretrimmedfortwoweeks,andallowedto regrowthenexttwoweeks.Itwasfoundthatduringthesetwoweeks,dendriticspineloss exceededthatofthecontrolgrouprate(naturalspinallossrate).Similarresultswere foundwhentrimmingwaslengthenedtofourweeks,andgrownandtestedoverthenext two. -Belowarethreecharts,twoconcerningtheeliminationoftheFilopodia,whichwill notbeincludedinthispaper,whilethefirstshowstheratiobetweensensorydeprived miceandnon-deprived,andtheirpercentageofspineloss. Running Head: Sensory Deprivation 8 EffectsofSensoryDeprivationinHumans TheCase A63yearoldwomancomplainedthatshewashearingvoicesforthepast11⁄2,to 2years,andthatthepresenceofvoiceshavebeenincreasingrecently,especiallyatnight. Initially,thevoicesfrightenedher,andshethoughtshewasgoingmad;thensherealized theywerenotreal.Shehadhearinglossinherleftearfollowingacaraccident5yearsago, anditwasrecommendedthatsheuseahearingaid.Duetothefactthattheaiddisturbed herear,sheuseditirregularlyfor3yearsandnotatallthereafter. Fivetosixmonthslater,shestartedtohearvoices.Everythingwasnormalinthe patient'spsychiatricexaminationexceptforauditoryhallucinationsandanxiousmood. Therewasnosubstanceuseorpsychiatricillnessinherhistory,andacompleteblood count,biochemicaltests,thyroidfunctiontest,EEG,cranialcomputedtomographyscan, Running Head: Sensory Deprivation 9 andneurologicalexaminationsofthepatientwereallnormal.The,“MinnesotaMultiphasic PersonalityInventoryandBeierSentenceCompletion”testswereevaluatedasnormal. TreatmentandProcedure “Treatmentwasstartedwitholanzapine10mgdailyanddiazepam10mgdaily. Later,diazepamwasstoppedandcontinuedbyolanzapine5mgdailyonly.Onthetenth dayoftreatment,theauditoryhallucinationsdisappeared.Thepatientwasobservedfor10 monthsatregularintervals;shetookolanzapine5mgdailyandusedahearingaidfor7 months.Duringthistime,nopsychopathologyhadbeendetected.”(CanadianJournalof Psychiatrypg.3) PhantomExtremityPhenomenon Animportantquestionmustbeaskedhere.Howdoesalossofhearinginonlyone ear,createsuchacaseashearingvoices?Therehavebeencountlesscaseslikethisone,and themajoritydonotleadtosomethingasfantasylikeashearingvoices.Thereishowever, anotherphenomenoninconcurrencewithsensorydeprivation,andthatisknownasthe, “PhantomExtremityPhenomenon.”Manyhaveheardofphantompains,leftbehindwith thelossofalimbeitherthroughamputationorothermeans.Damagetothesensorynerve canaffectreuptake,andothercomponentsofthesensoryneurons,creatingafeelingthat thelimbisstillthere,throbbinginpain.Thisoperationissimilartowhatishappeningin thiscaseoflostsenseofhearinginoneear.Inbothcasesthestimuligoingtothecortexis Running Head: Sensory Deprivation 10 blocked,butitisstillunknownastohowthisperceptualdisorderoccurs.Thereisatheory thatthisiscausedbyreceptorhypersensitivity. “Thiscouldbeexplainedbyexaminingtheeffectivemechanismsofhallucinogens andatypicalantipsychotics.Hallucinogensandserotonin-dopamineantagonists(SDAs)act throughthesamereceptorsbutcreatedifferenteffects.Hallucinogensactivate5HT^sub 2A^,5HT^sub2C^,and5HT^sub6^receptorsandcausehallucinations.Incontrast,SDAs blockthesereceptorsandpreventtheformationofhallucinations.”Theparametersforthe CharlesBonnetSyndromeareallmetwiththisspecificcasestudy.However,itwasinitially discardedasapossibleanswer,simplybecauseCBSdeals,orhasonlydealtinthepast, withvisualhallucinations,notauditory.However,becauseitwasproventhroughmultiple teststhatthewomanwaspsychologicallysound,carriednodisorders,andrecognizedthe hallucinationsasimaginaryamongotherpivotalcriteria,thecasemayprovetobewhatis neededtoexpandtheworkingdefinitionofCBS,toincludeauditoryhallucinationsaswell, andpotentiallyevenothersensicallybasedhallucinations. Running Head: Sensory Deprivation 11 BringingitBacktoLilly Whenwelookatthiscase,aswelookedattheresultsproducedfromsensory deprivationchambertestsdonebyLilly,wecanbegintotheoriseonourown,usingLillys dataasabasis.Itcanbereasonablyinferred,thoughnotscientificallyprove,thatperhaps thecauseofthewoman'simaginaryvoiceswasmuchlikethehallucinationshavingbeen reportedinS.D.Ctests.Duetoalackofsensoryinputtothecortexforanextendedlengthof timefromthedamagedear,thebraincreatedit’sownsensoryinputinanattempttofillthe void.Muchlikehallucinationscausedinthedeprivationchambers,broughtonbyalackof sensorystimulus,themindcouldthencreateitsownstimulus,causingvoicestobe, “heard,”inthedamagedear, Itisisscientificknowledgethatthebrainisthecontrolcenterofthebody,making sureallsystemsoperateefficiently,andevensacrificingorganstosaveitself.Thebraincan becalledacontrolfreak,asitdominatesallotherorgans,assuringthebodyrunstheway thebrainintendsitto;mendingerrorswhenneeded,andmaintaininghomeostasis.For thesereasons,inanattemptto,“restorebalance”tothewoman'sdamagedbody,thebrain createdauditorystimulusthatseemedtocomefromthedamagedear,inorderto,as stated,“fillthevoid”. Thisis,ofcourse,merelyapersonalhypothesisonlylooselysupportedbycasestudy evidence.However,onecouldfindtheretobemerittothistheory,andtheremayalready beresearchavailabletosubstantiatethisclaim.Manyopposingfactsarepresent,oneofthe mostloomingbeingcasesoftheblind.Ifthereweretobeacaseofhallucinationduetothe sensorydeprived,itcertainlywouldhavebeenheardmoreofinthosewhoareblind.This Running Head: Sensory Deprivation 12 howeverdoesnotincludethosebornblind,norperhapseventhosewhowentblindata youngageasthespinalstudyinmicemaysupport;butthosewholosttheireyesightlater intheirlifewillbeaninterestingplacetostartinsearchforvalidation,ordestructionof saidtheory. Running Head: Sensory Deprivation 13 References AnnalsoftheNewYorkAcademyofSciences,1225:110–118,April2011. ElaineWen-Biao,GanGuangKwon,Zuo,YiYang,(2005)Long-termsensorydeprivation preventsdendriticspinelossinprimarysomatosensorycortex,NewYorkUniversity SchoolofMedicine. Keck,T.,Scheuss,V.,Jacobsen,R.I.,Wierenga,C.J.,Eysel,U.T.,Bonhoeffer,T.,&Hübener,M. (2011).Lossofsensoryinputcausesrapidstructuralchangesofinhibitoryneuronsin adultmousevisualcortex.Neuron. MasonOJ,BradyF,Thepsychotomimeticeffectsofshort-termsensorydeprivation.(2009) DepartmentofClinical,Educational,andHealthPsychology,UniversityCollege London. RobbieGonzales,EverythingYouEverWantedToKnowAboutSensoryDeprivationTanks, (2011),Gizmodo/Io9 Yuksel,F.V.,M.D.,Kisa,C.,M.D.,Aydemir,C.,M.D.,&Goka,E.,M.D.(2004).Sensory deprivationanddisordersofperception.CanadianJournalofPsychiatry.