title: The clitoral photoplethysmograph: a new way of assessing genital arousal in women.
abstract: BACKGROUND
  In the present study, we introduce clitoral photoplethysmography as an instrument to assess clitoral blood volume (CBV). In research on female sexual functioning, vaginal pulse amplitude (VPA), as measured using vaginal photoplethysmography, has been used extensively as a measure of vaginal vasocongestion. Measurement of clitoral blood flow has thus far been problematic, mainly because of methodological constraints.
  
  
  OBJECTIVE
  To demonstrate that CBV is a valuable, easy to use complementary measure for the female sexual response, offering additional information to the VPA.
  
  
  METHODS
  Thirty women with and without female sexual dysfunction (FSD) watched neutral and erotic film clips. At the end of the erotic clip, the session was interrupted to induce inhibition of the sexual response. Another neutral clip followed the interruption. VPA and CBV were measured simultaneously, as well as skin conductance levels (SCLs), to assess the amount of sympathetic activity.
  
  
  METHODS
  VPA, CBV, SCL.
  
  
  RESULTS
  For both FSD and non-FSD women, VPA and CBV increased when sexually explicit material was presented. Changes in skin conductance significantly predicted changes in CBV (b = -0.61, t[27] = -3.88, P < 0.001), but not in VPA. A large increase in sympathetic activity was accompanied by a large decrease in CBV. Furthermore, a large increase in CBV at the end of the erotic film clip presentation, as compared with the neutral clip, was accompanied by a relatively small increase in VPA (b = -0.39, t[29] = -2.25, P < 0.033).
  
  
  CONCLUSIONS
  CBV is a valid and sensitive tool to measure the female genital response. In the present study, it was particularly useful in investigating sexual inhibition, when used in combination with SCL. Furthermore, high CBV appeared to inhibit VPA, suggesting that VPA reflects an automatic preparatory response rather than genital arousal per se.
authors.affiliation: Emotional Brain BV-R&D FSD, Almere, the Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Gerritsen
authors.affiliation: Emotional Brain BV-R&D FSD, Almere, the Netherlands; Department of Gynecology and Obstetrics, Flevoziekenhuis, Almere, the Netherlands.
authors.forename: Flip
authors.initials: F
authors.lastname: Van Der Made
authors.affiliation: Emotional Brain BV-R&D FSD, Almere, the Netherlands.
authors.forename: Jos
authors.initials: J
authors.lastname: Bloemers
authors.affiliation: Emotional Brain BV-R&D FSD, Almere, the Netherlands.
authors.forename: Diana
authors.initials: D
authors.lastname: Van Ham
authors.affiliation: Department of Gynecology and Obstetrics, Flevoziekenhuis, Almere, the Netherlands.
authors.forename: Gunilla
authors.initials: G
authors.lastname: Kleiverda
authors.affiliation: Department of Social Sciences, Clinical Psychology, University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Walter
authors.initials: W
authors.lastname: Everaerd
authors.affiliation: Department of Psychopharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, the Netherlands; Rudolf Magnus Institute of Neuroscience, Utrecht University, Utrecht, the Netherlands; Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA.
authors.forename: Berend
authors.initials: B
authors.lastname: Olivier
authors.affiliation: Sexual Physiology Laboratory, Porterbrook Clinic, Sheffield, Yorkshire, England.
authors.forename: Roy
authors.initials: R
authors.lastname: Levin
authors.affiliation: Emotional Brain BV-R&D FSD, Almere, the Netherlands; Department of Gynecology and Obstetrics, Flevoziekenhuis, Almere, the Netherlands; Department of Psychopharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, the Netherlands. Electronic address: a.tuiten@emotionalbrain.nl.
authors.forename: Adriaan
authors.initials: A
authors.lastname: Tuiten
mesh_terms: D000328:Adult; D002987:Clitoris / Q000033:anatomy & histology* / Q000502:physiology; D005260:Female; D005836:Genitalia, Female / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D017156:Photoplethysmography / Q000379:methods*; D020018:Sexual Dysfunctions, Psychological / Q000175:diagnosis*