Modulationofspinalreflexesbyaversiveandsexually appetitivestimuli STEPHANIEBOTH,WALTEREVERAERD, AND ELLENLAAN DepartmentofClinicalPsychology,FacultyofSocialandBehaviouralSciences,UniversityofAmsterdam,Amsterdam, TheNetherlands Abstract In this study, modulation of spinal tendinous (T) reflexes by sexual stimulation was investigated. Treflexes are augmentedinstatesofappetitiveanddefensiveactionandmodifiedbydifferencesinarousalintensity.Reflexeswere expectedtobefacilitatedbybothpleasant(sexual)andunpleasant(anxiety)stimuli.Subjectswereexposedtoasexual, an anxiety-inducing, a sexually threatening, and a neutral film excerpt. Genital arousal, emotional experience, subjectiveactiontendencies,andTreflexesweremonitored.Self-reportandgenitaldataconfirmedtheaffectivestates as intended. Treflex amplitude significantly increased during viewing of emotionally arousing film excerpts as comparedwithaneutralfilmexcerpt.Treflexeswerefacilitatedbythesexstimulustothesameextentasbytheanxiety andsexualthreatstimuli.Theresultssupporttheviewofsexualarousalasanemotionalstate,generatingsex-specific autonomicandgeneralsomaticmotorsystemresponses,whichpreparetheorganismforaction. Descriptors: Emotion,Motivation,Sexualarousal,Anxiety,Treflex,Reflexmodulation Foralongtimeithasbeenknownthatreflexesaremodifiedby cognitiveandaffectivevariables.Lang,Bradley,andCuthbert (1990) proposed that affective modification of the startle response reflects motivational priming, in which a defensive reflexsuchastheeyeblinkispotentiatedwhenelicitedinthe contextofanongoingaversivestate,andinhibitedwhenelicited inanonprimedcontextthatinvolvesapproachbehavior.Langet al.showedthatthehumanstartlereflexisindeedfacilitatedby aversivestimulianddiminishedbypositivestimuli.Incontrastto startlereflexes,tendonreflexesarenotsensitivetothevalenceof theaffectivestate.Theyareaugmentedinstatesofaction,and they are modified by differences in arousal (Bonnet, Bradley, Lang,&Requin,1995;Brunia&Boelhouwer,1988).Therefore, investigationoftendonreflexmodulationoffersawindowonthe generation of action. In this experiment, we investigated modulation of spinal tendinous reflexes by emotional arousal, specificallysexualarousalandanxiety. Emotioncanbeviewedasfundamentallyanactiondisposi- tion,atendencytodosomething(Frijda,1986;Lang,1993).In thisview,emotionsservethesatisfactionofgoalsandgenerate relevant action (fight–flight or approach). For example, when afraid,youmayfeelastrongurgetorunaway,andwhensexually attractedyoufeelastrongdesiretobeasclosetotheattractive personasyoupossiblycan.AccordingtoLang,emotionsare driven by two primary motive systems: the appetitive system, prototypically expressed by behavioral approach, and the aversivesystem,expressedbybehavioralescapeandavoidance (Lang et al., 1990). There is, therefore, a strong resemblance between emotion and motivation; both are fundamentally relatedtoaction.Bindra(1974)alreadynotedthat‘‘motivational state’’and‘‘emotionalstate’’areinterchangeableterms.Emo- tionsmovetheorganismtowardsorawayfromobjectsinthe environment. Sexualexcitement,inthisrespect,doesnotdeviatefromother emotions: Sexual excitement serves to satisfy concerns, and generatesanactiontendencyforsexualbehavior(tocontinue,or search for, sexual stimulation; Everaerd, Laan, & Spiering, 2000).Incentivemotivationtheoriesstatethatmotivationisthe resultoftheinteractionofhomeostaticdrivesandenvironmental stimulithathaverewardingproperties(incentives).Incentivesare supposed to guide response selection through excitatory or priminginfluenceofthecentralmotivestateonsomatovisceral reactions,consummatoryorrejectionalacts,andlocomotorand skilled actions (Bindra, 1974). Following incentive motivation models,sexualmotivationisanemergingproperty,theoutcome oftheprocessingofinternalorexternalsexualstimuli(Everaerd, Laan,Both,&Spiering,2001;Singer&Toates,1987).Hence, sexual motivation can be investigated best by studying the processofactiongeneration.Thisprocesscanbestudiedthrough the monitoring of responses within various response systems involved in general motivated behavior and specific sexual behavior. Appetitivebehaviorincludeslocomotorapproachresponses tothegoalorexploratorybehavior,andoccursinparallelwith WethankLarsvanDalen,JanineHooijboer,andPeter-PaulMantjes fortheirassistanceinthedatacollectionanddatareduction. Addressreprintrequeststo:StephanieBoth,DepartmentofClinical Psychology,FacultyofSocialandBehaviouralSciences,Universityof Amsterdam,Roetersstraat15,1018WBAmsterdam,TheNetherlands. E-mail:kp_both@macmail.psy.uva.nl. Psychophysiology,40 (2003),174–183.BlackwellPublishingInc.PrintedintheUSA. Copyright r 2003SocietyforPsychophysiologicalResearch 174