Corticifugal influences on reticular formation evoked activity in cats

EXPERIMENTALNEUROLOGY

34,511-521(1972)

Corticifugal Influences on ReticularFormation EvokedActivityinCats D .F .LINDSLEY,S

.K .RANF,ANDR

.J .BARTON'

DepartmentofPhysiology,UniversityofSouthernCaliforniaMedicalSchool, LosAngeles,California90033 ReceivedNovember17,1971

Corticifugalinfluencesdescendingthroughthesubthalamushavebeenpostulated toberesponsibleforitsroleindeterminingtheexcitabilityofthereticularformation(RF)andmaintainingtheattentive,affectiveandmotorbehaviorofthe animal .Supportforthisconceptcomesfromacuteexperimentsinvolvingcooling ofthesecondarysomatosensorycortex(SSII)inunanesthetized,immobilizedcats

.

BilateralcoolingofSSIIreducedtheamplitudeofsciaticevokedpotentials(EP) alongthelengthofthebrainstemRF,thoughreductionsinEPofmidbrainRF weremoreconsistentthanthoseinthemedullaryRF .SciaticEPinsensoryand motorareasatcomparablelevelsoftheneuraxis,includingventralisposteriorlateralis,showedlittleornochange .Theseresultssuggestthatthecortexcanexert tonicfacilitatoryinfluencesontheRF .CoolingofSSIIalsodecreasedtheamount ofinhibitoryinteractionbetweenpairedsciaticEPintheRFwhichimpliesan interferencewithphasic,inhibitoryinfluences .ExtirpationofSSIIhadmuch thesameeffectascoolinginreducingsciaticEPintheRF .Unilateralremovalof SSIIproducedasignificantdecreaseinsciaticEP

;subsequentremovalofcon-

tralateralSSIIresultedinstillmorereductionimplyingthatthesecorticifugal influencesoriginatebilaterally,thoughtheipsilateralprojectionmaybemorepronounced .PersistenceofsciaticEPintheRFafterbilateralextirpationorprolongedcoolingofSSIIsuggeststhatotherareasofthecortexarealsoinvolved indeterminingtheexcitabilityoftheRFtoenteringsensoryinput .

Introduction Theroleofcorticifugalinfluencesinsensory,motorandbehavioral mechanismsisanareaofcontinuingresearchinterest

.Inparticulartheir

relationshiptothereticularformation(RF)hasbeenthesubjectofnumerousanatomical(8,14,13,24)andphysiologicalstudies(4,3

.10-13 .21) .

TheimportanceofthesecorticifugalsystemsforthemaintenanceofsubcorticalactivityhasbeenillustratedbyspreadingcorticaldepressionexperimentswhichproduceseveredepressionofthethalamicandmidbrainRF 'TheresearchwassupportedbygrantsNS07865fromtheNationalInstitutesof HealthandGB-31540fromtheNationalScienceFoundation .Theauthorsgratefully acknowledgethehistologicalassistanceofMrs HigginsandthetechnicalassistanceofMissMarjorieJ 511 ©1972byAcademicPress,lnc

.

.JudithBeckmanandMrs .Sherwood .

.Joan



5 12

LINDSLEY,RANFANDBARTON

andthehypothalamus (28,29) . Recentlyexperimentsinvolvingcooling andstimulationofthecortexhaveindicatedthatcorticifugalinfluencesare essentialforthedevelopmentofsensoryevokedpotentials(EP)(22,23) .Alsosurgical andunitactivity(7,31)inreticularandmidbrainregions isolationofthemidbrainindicatesthatthebackgroundEEGactivityofthe RF"isdominatedalmostexclusivelybyinputfromtheipsilateralforebrain" (30) . Onthebasisofsubthalamiclesionexperiments,corticifugalinfluences passingthroughthesubthalamushavebeenpostulatedtoplayanimportant roleindeterminingtheexcitabilityoftheRFtoenteringsensoryinputand inmaintainingattentive,affectiveandmotorbehavioroftheanimal(1,3, 17-19) . Rabin(23)proposedthatthereisselectivecorticalcontrolof reticularevokedactivityandconcludedthat"thesecondsomatosensory zoneofthecortexcontrolsresponsesoftheso-callednonspecificstructures ofthebrain ."Thepresentexperimentsweredesignedtostudytheprojectionsofthesecondarysomatosensorycortex(SSII)atthoselevelsofthe . RFwhichhavebeenshowntoreceivesubthalamicfacilitatoryinfluences Methods Theresultswereobtainedinacuteexperimentson17cats .Allsurgical maneuverswereperformedunderetheranesthesia,afterwhichtheanimals 0 .13 nag/ wereimmobilizedwithgallaminetriethiodide(Flaxedil,about min),andallsurgicalincisionsandpressurepointswereinfiltratedwith procaineinpeanutoil(Zyljectin,Abbott) .Norecordingsweretakenforat .Allsubcorticalreleast2hraftertheconclusionoftheetheranesthesia cordingsweremadewithbipolar,stainlesssteel,concentricelectrodeswith asheathdiameterof0 .5mmandacentralconductor0 .2mmindiameter whichprojectedabout0 .5mmbeyondtheshoulderofthesheath .Sciatic stimuliasusedinthisexperiment (2-3 v,1msec,onceper 30 sec ;orinthe inhibitoryinteractionexperimentspairedsciaticshocksatintervalsof5017) . 100msecgivenonceper 30 sec)donotevokepainfulresponses(16, Thebodytemperaturewasmaintainedat38Cbyusinganinfantheating blanket.CoolingofSSIIwasperformedbilaterallybyplacingphysiological salineiceslushovertheintactduramater ;thecortexwaskeptwarmbefore coolingandrewarmedbyapplicationofphysiologicalsalinesolutionatbody temperature .Inexperimentsinvolvingremovalofthecortexsuctionwas used ; theduramaterinthesecaseshadbeenremovedduringtheinitial surgery .Allelectrodeplacementswereverifiedhistologicallyinfrozen sectionsstainedbytheNisslmethod . Results Effects of Cooling the Secondary Sonmatosensorv Cortex on Sciatic EvokedPotentialsintheBrainSteinReticularFormation . Sciaticevoked



513

RETICULARFORMATION

potentialsatalllevelsoftheRF(anterior-posteriorlevelsA5toP13accordingtothestereotaxicatlasofSniderandNiemer,25)werereduced bybilateralcoolingofSSII(Fig .1) .SciaticEPintheanteriormidbrain RFweremoreconsistentlyaffectedthanthoseintheposteriormidbrain RF(uppertraces,Fig .1) .TheywerealsodecreasedinthemedullaryRF (P13 ;lowertraces,Fig .1),butthereductionwasmorevariablethanin themidbrainRF .UsuallythemajorreductionsinsciaticEPappeared withinthefirst1-5minofcooling,andprolongationofthecooling periodforeven10-20minproducednofurthersignificantchanges aslongastheanimalpreparationremainedingoodcondition .Inmostexperiments,bilateralrewarmingofthecortexrestoredtheEPwithin5-15 min,thoughsometimestherewereminorchangesinthelatencyandshape oftheresponseascomparedtocontrolresponses .Unliketheamplitude changes,theredidnotappeartobeanystrikingalterationsinthelatencies ofthesciaticEPfollowingcorticalcooling . EffectsofExtirpationofSecondarySontatosensoryCortexonSciatic EvokedPotentialsintheMidbrainReticularFormation . Sinceprolonged

coolingdidnotabolishsciaticEPintheRF,extirpationofthecortexwas

CONTROL

COOL

REWARM

I

AO

MBRF

I

A4

t

MEDRF

I

MBRF J I

t

_

FIG .1 . Effectsofbilateralcoolingofthesecondarysomatosensorycortexonsciatic evokedpotentialsinthemidbrainandmedullaryreticularformation .Theupperthree photographsshowtheeffectsofcoolingonsciaticEPintheposteriormidbrainRF (AO)andtheanteriormidbrainRF (A4) . Thelowersetofphotographsrepresents themedullaryRFandthemidbrainRF .NotethatcoolingdecreasedsciaticEPalong thelengthoftheRF .Abbreviationsinallfigures : MBRF,midbrainreticular formation ;MEDRF,medullaryreticularformation ;SSII,secondarysomatosensory cortex ;VPL,ventralisposteriorlateralisofthethalamus .Lettersandnumbersunder abbreviationsofbrainregionsrefertodifferentanterior-posteriorlevels .Inall figuresarrowsindicateonsetofstimulus .Allverticalcalibrationsare50rvandall horizontalrepresent20msec .



514

LINDSLEY,RANFANDBARTON

attempted .However,removalofSSII,likecooling,producedaconsiderable ( Fig.2) . reductioninsciaticEPbutdidnotleadtotheircompleteabolition Intheseextirpationexperimentsitwaspossibletoassessthecontribution ofthetwosidesofthebrain .EvokedpotentialswererecordedinthemidbrainRFtostimulationofthecontralateralsciaticnerve .RemovalofSSII ipsilateraltothemidbrainrecordingelectrodescausedalargereductionof sciaticEP .Subsequentremovalofthecontralateralcortexresultedinstill furtherdecrease,particularlyintheanteriormidbrainRF .TheseEPreductionsfollowingtwo-stagelesionssuggestthatcorticifugalinfluences originatebilaterally,thoughtheipsilateralprojectionmaybemorepronounced .PersistenceofsciaticEPfollowingbilateralcorticalextirpation, aswasthecaseafterprolongedcooling,pointstotheinvolvementofother corticalareasbesidesSSIIindeterminingtheexcitabilityoftheRFto enteringsensoryinput . EffectsofCoolingSecondarySomatosensoryCortexonSciaticEvoked . InthreeexperiPotentialsintheNucleusVentralisPosteriorLateralis mentselectrodeswereplacedintheRFandinVPL,inordertodetermine ifcoolingofSSIIalsoaffectedsomatosensoryEP .Figure3indicatesthat, thoughEPofmedullaryRFtosciaticstimulationweregreatlyreduced bybilateralcoolingofSSII,sciaticEPinVPLshowedlittleornochange . InFig .4,Exp .1showsessentiallythesameresult ;thestippledarea representsthedegreeofinhibitoryinteractioninVPLforpairedsciatic stimulispaced100cosecapart .Thereislittleinhibitoryinteractionduring eitherthecontrolperiodorduringcooling, i .e ., thesciaticEPinVPL changedlittleinamplitudewithpairingofsciaticstimuliorcoolingof SSII .Thusitappearsthatthecorticifugalinfluencesdemonstratedinthese experimentsbycoolingofSSIImainlyalterreticularexcitabilityandhave muchlesseffectonthedorsalcolumn-mediallemniscussystem . CONTROL

REMOVER .SSII

REMOVEL .SSII

R .MBRF A4

FIG. 2.Effectsoftwo-stageextirpationofthesecondarysomatosensorycortexon .NotethatipsilateralremovalofSSII sciaticevokedpotentialsinthemidbrainRF producesalargereductionofsciaticEP,andsubsequentremovalofcontralateral .Alsoobservethatevenafterbilateralremovalthere SSIIledtoafurtherdecrease arestillsciaticEP .



515

RETICULAFOMN

CONTROL

COOL

REWARM

MEDRF

VPL

1

1

1

FIG . 3 .Efectsolinghecdarysomtncrexosiatvkd

.Coling

potenialshmduryeticlafomndvetralispo teralis ofSIcausednirbluctonfsiaEPthemdularyRFbite changeofsitEPVL

.

EfectsoClingSdaryoztsenCrxoPaiedSct StimulsIneracoithRularFomtin

.

Thexprimntsdcbe .Therfo,ts

aboveinldusfgetimlohscanerv decrasintulEPcasedbyoingfSIcabeosidrt

.Useof

repsntifcewhtoni,xaryfluencstohRE .4,isamenofurg

pairedsct muli,a strednFig inhbtoryeacin

.Theriscondabltercionwpared ; bilatercongf

sciatEPnhemdbriRungcotlperids SIreducthisnboryeactin

.InExp

.1atsimulnervof

10msecinhbtory acinthemdbrRFcasefom40t 27°%o

andrewmigtudhelvo39%

.InExp

anotheriml wasenhibtory acnimorepst midbranRFplcethinExp teracionfm2719%at

.1,butsilcongredui-

50

thelvo

cosepaingdrwm ceasd

32% . Thus,colingtyreduchampliteof

firstEPohepa wniFgs

.1-3,whicanbetrud

toimparenfc,xitaory cfuglines,btcolinga resultdinagecoEPthanxped

.Thisdecranbitoy

interacoup lingsetharwsimpentofhac, inhbtoryfluecs

.

ComparisnftheEcoClingSedaryomtsnCrex onSciatEvkedPnialsVrouDencphalidBrStem Regions .

Table1prsntumayofheistlgcayvrfiedlto

placemntsih17alnvoedithsclngudie,SatcEP inthebrasmREoinegrlatdoheRE,suctzona incerta,showdm niterducosaeltfcingoSH thanEPioerlctns notperfmd REplacemnts,uh oryandmt])iseloc,hwdite

; howevr,asytmicehofbranws .Evokedptnialsveofthnuraxiscmpbletoh

.2involg



5 16

LINDSEY,RAFBTON

ornchagewit lcong RFwermocnsitlyadevrfcthanEPiepostr midbranRFtheularyRF,thogcmparisnthebof onlythremduaRFplcentsidful intmaelyr dothRFalswedcng therwfouinsacewhtrasnice atEP duringcol dtwoinhezacrt comprisetal cngeofthalumbrteionsbrvd todrawnyefivcolusn,btheymarsulfoipment tonic,rfugalnhibtoryfuecs examplsofuchinbtryfluecswnotd

.Evokedptnialsferomdbain

.Thezonicrtawhs .Table1indctsh .Thesincra EP

.Therisnoxplatwhymre .Thus,tedafrom

50-

CONTRL EWAM

CONTRL EWAM EXPRIMNT1

FTC .4

.

interacofpdsiatcevokpnialsthemdbrn ventralispo teralis interacodminbysutracg sciatEPofehprmtiscaEPndivgbytheamplud oftheirscaEP shown ; inExp thesimulnrvae50msc interacoVPL thaerisnomuchbtry andcoligfSIhastleconhitra inhbtoryeacinthRFdurgcolpeids, byilatercongfSI

Effects of colingthe

EXPRIMNT2

cortex on theinbory reticulafomnd

secondarymts . Theordinatps

theprcnagofibtry second

theavrgofmplitudeh oftwexprimnsdfetaimls

.Thersult .1thescia mulre

are .2

spaced10m rtniExp .ThestipldbarnEx

.1repsntihbory

;theblankrsmueofticlarn o

. Note period,

interacoVPLduingthecorl . Howevr,thiscndeabl andthisercodu .



517

RETICULAFOMN

Table1indcthSIplaysnimort lehcnroftiula excitablynderswipanfluecsovrthngfeicular core. Discussion Theprsntulidcaehtorifugalnecs,prtiulayfom SI,havenimport ldemingthrspovenfthRF toenrigs yput

.AdeyanLisl(1)potuaedhcrifugal

fiberspangthouesbalmpyignfcatregulin thexciablyoftheRFndmai gthenivbaorfthe animal .AlsoRabin(23)reptdhaSIconrlseyvkdrticularctivy RFcomesfrth nwokfOstrichadPle(2)woshd thedpncofvkedrspnithudl RFjunctiohef nalstoSIdanthemibrRF unitsdeofBr,RichadnLesop(7)Zilv Thefindgstpreudyinvolgc fSIaresimlto thefcsoubalmieons ryEPitheRF(1,9) Corticfugale sdmontraebyhcilong(Tabe1)d subthalmiceons(19)arditbuelongh tfebrainsm RF,thougerapstobdifernalsucptibyvarousle

.Furthespof imrtanceof iuglnptohe .)rainpequdctlgray(31) . : (a)

TABLE1 COMPARISNFTHE ONSCIATEVKDPNIALSVROUDENCPHALIBRSTEMGION

EFCTSOLING

THESCONDARYMESCORTX

1

T

-

RF

J

T

VPL ;OTHERBAINSM A .MBRF

6

P.MBRF

6

MED .RF

3

THAL.&SUBTHAL

VPL

2

CUNEAT

.

2

.

INF .OLIVE

1

1 1

CERE.PED 1

.

3

INF .COL,

.

ZONAICERT P .THAL

1

1

3 1

REDNUC

4

.

2 1

Thistablerpnsumayoftheilgcayvrfiedltopacmens inthescolgudi suchatezonir,shwedmocnitreduoshanEPieryo motrlciapbevlsofthnuraxicldg midbranetculfomin VPL,ventralispo teralis cerbalpdun

.NotehasciEPnteRForgislatedohRF,

;INF

; MED RF,medulary ;INF . OLIVE, inferolv

;P .COL

.,inferoclus .

VPL_ Abbreviations :MBRF, .Thai .,posterihalmu ;CER .PED

; .,



5 18 oftheRETmidbranFsoevlyafctdboinga lesionthamdulryRF,anteiomdbrngshowmre consitealronhmepstriodbanegs(Fi Unilaterco mval(Fig wasnotefcivabltersion work(Fig .2)andthofers(7,23)thaemosprnucd cortifugale srxtdonhemibraspon ilterah cortexldan rtelohsmaictul cortialemv(Fg efctivhanulersio atdifernlvsothRFadeirbltognsuethacorifugaliberscnxthfecsovrwidpatonsfheRF (c)Thersultofica ngromtheps udy(Fig Table1),thosfrmOicandPolster lesionxprmt(1)idcaehortifugalnecsrmuho efctivonhRFaprimysotenrlcisuhaVPL ThescortifugalnpsotheRF,wxamindorespcfalyuing pairedsct muli(Fg studies (1), consitf exaoryndphsicbtorynfluecs Therfo,tsimlayofhersutmcoial ngdfrom subthalmiceonsudmplietha somfthedcnig influecspagthrouesalmtkorignfSI Themainpotfdrecbwnthsulrepodhan thosefRabin(23)thdegrowicSIxersontlvhe responfticulareonsmticulaon "insomexprthsoneiRFwalmostcpey supred,"aniFg RFdisaper ."Suchfindgslemtocudhaivtyne RFtocnralesmticnrv ulao,"depnsirctlyohe functioalsehcondmatserycox,"andltepros tha,"escondmt rycoexntlshrpoeftRE"In theprsnudymajorchngesitularEPweobsvdithn thefirs5mn,adpolgecinfr10-2madevnxtirpof SI(Fig .2)dinotablshciEPongastheimlrnd ingodct .Thesrultg haoersftnocex, suchateprimyosnrctex,adhlimbcsyteao playroeindtmghexciabltyofhRFenrigsoy input .ThercntwokfOsihadPlter(2)incasht,loug colingfSIausedmor ctinfadlervEPinthmdba periaqudctlgy-RFjniothadclngfST,oibth togehrpduc geatr s ventralgmu(editohrnuclesadvtroheculmr

LINDSEY,RAFBTON

.1)

.(b)

.2)orunilatesbhmiclon(1) .Italsoperfmhsnt

.Howevr,bilat .2)orbilatesuhmiclon(1)wasre .Thus,tevidncfortugalinfecs . .3and (22), andthosefrmubalic .(d) .4),asprevioulyhwnsbtamicleon .

.

.Heobsrvdtha, .3ofhispaertd,"hesponit

.TheyalsobrvdtEPinhe

519

RETICULAR FORMATION

.Thisdfernc

nuclei) showednigfcatlerionsdugcl inresultmaybdohefctaOsrindPolte(2)rcd EPfromthedialRF(bu0 presntudivolemrat iculregons(abt3mfr themidln) therisnoxpla frthedi ncasuhmedilrtcapnetionswerpfmdintherswok diferncs,thudiofOrchanPlste(2)dhcolingexprmentsrpodhugestawidr ofthecxmayinvoled incotrlgeuaxcitblyhnia dctebyRin Othervidncosupthinclsomefrthwko Adey,SgunoaLivst(2)whoedatsimulonfheppocamlgyrsudinfecotnalghericuo exprimntsofLdley,ZarndMot(19)emnsradth reductions aEPcresdwith zofesubthalmicons, implyngthafuecsromwidathenorsictedaof cortexaimpnregulati crextabily ofBuser,RichadnLop(7)Zilv31showtaclingd stimulaonfSTrespctivlyoudnfecthaivyofRFneurs Finaly,thebvorwkfAdeyanLisl(1)vongubthalmicesondfSprague indcateh ivbaorndtheiml'sponvetsry inputcabemrdylsionveacdrblxtenofhdicephalondmibr fromvaiusnectladimbres tibudowespra regionsfthRFadreimpont righexctabliyofhe RFtodiferns yput possible, asBter,undSiberg(6)anR 23hvesown, forctiugalnfecstoxrmdaliy-specf tonricula regions .Alsocrtifuganhborystemavbnrpoted(9,1 20) : intheprs udyoviencft hbionwasfud,t phasicnbtoryfluecswobrvd ofinvlemtdfrncoiugalfencstypariulme, whetrinboyfaclitr,ndhea(s)ofcrtxmwhi theyaris,pobldensthiraconfvusbraiytemnd thebaviorls ftheanim

.5mfrotheidln),wrasthe .Exceptforhusni oxdethrpimns .Thus,aprtfome

(23) .

.The

.Alsotheudi . etal

. (26,7)withlaermdbnsio

.Takentoghrsudiegthanfluecs

.Withnsgeralcm,howveits

.Thus,itaper hdg

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. FIFKOVA . 1961 . Bioelctravyinhetlamusdypo.,andE thalmusofrdingctalspredingEGso Neurophysiol . 13 : 734-744 . 30 . ZERNICKI, B .,R . W . DOTY, andG . SANTIBANEZ-H . 1970. Isolatedmibrncs Electroenceph .Clin .Neurophvsil . 28 : 221-235. 31 . ZILOV, V . G . 1970. Corticalndhyp micfluensog rnf

Bohenzoslov . 10 : 109-

29 . WEis,T

mesncphalirtufomain from Fi.iolgcheskZurnalSRie1 1969.

. Neurosc .Transltio13 .31.Sechnova

. Electroenceph .Clin

. .

: 75-83. Translated 55 : 1326-1333,