title: Unmyelinated tactile cutaneous nerves signal erotic sensations.
abstract: BACKGROUND
  Intrapersonal touch is a powerful tool for communicating emotions and can among many things evoke feelings of eroticism and sexual arousal. The peripheral neural mechanisms of erotic touch signaling have been less studied. C tactile afferents (unmyelinated low-threshold mechanoreceptors), known to underpin pleasant aspects of touch processing, have been posited to play an important role.
  
  
  METHODS
  In two studies, we investigated the relationship between C tactile activation and the perception of erotic and pleasant touch, using tactile brushing stimulation. In total, 66 healthy subjects (37 women, age range 19-51 years) were examined. In study 1 (n = 20), five different stroking velocities were applied to the forearm and the inner thigh. The participants answered questions about partnership, mood, and touch. In study 2 (n = 46), the same five stroking velocities were applied to the forearm. The participants answered questions about partnership, touch, and sexuality.
  
  
  RESULTS
  Both touch eroticism and pleasantness were rated significantly higher for C tactile optimal velocities compared with suboptimal velocities. No difference was found between the ratings of the thigh and the forearm. The velocity-dependent rating curves of pleasantness, intensity, and eroticism differed from each other. Pleasantness was best explained by a quadratic fit, intensity by a linear fit, and eroticism by both. A linear transformation of pleasantness and intensity predicted the observed eroticism ratings reliably. Eroticism ratings were negatively correlated with length of relationship.
  
  
  CONCLUSIONS
  Touch was rated most erotic when perceived as pleasant and weak. In human hairy skin, perception of pleasantness is correlated with the firing rate of C tactile afferents, and perception of intensity is correlated with the firing rate of Aβ afferents. Accordingly, eroticism may be perceived most readily for touch stimuli that induce high activity in C tactile fibers and low activity in Aβ fibers.
authors.affiliation: Department of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Emma H
authors.initials: EH
authors.lastname: Jönsson
authors.affiliation: Department of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Backlund Wasling
authors.affiliation: Department of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Vicktoria
authors.initials: V
authors.lastname: Wagnbeck
authors.affiliation: Department of Neuroscience, Section Anatomy, University Medical Center Groningen, Groningen, the Netherlands.
authors.forename: Menelaos
authors.initials: M
authors.lastname: Dimitriadis
authors.affiliation: Department of Neuroscience, Section Anatomy, University Medical Center Groningen, Groningen, the Netherlands.
authors.forename: Janniko R
authors.initials: JR
authors.lastname: Georgiadis
authors.affiliation: Department of Clinical and Experimental Medicine, IKE, Linköping University, Linköping, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Olausson
authors.affiliation: Department of Clinical and Experimental Medicine, IKE, Linköping University, Linköping, Sweden.|Department for Psychotherapy and Psychosomatic Medicine, Dresden University Hospital, Technische Universität Dresden, Dresden, Germany.
authors.forename: Ilona
authors.initials: I
authors.lastname: Croy
mesh_terms: D000328:Adult; D000339:Affect; D001143:Arousal / Q000502:physiology*; D004644:Emotions; D005260:Female; D005542:Forearm / Q000294:innervation; D006801:Humans; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D008875:Middle Aged; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology*; D010812:Physical Stimulation / Q000379:methods*; D012867:Skin / Q000294:innervation*; D011795:Surveys and Questionnaires; D013848:Thigh / Q000294:innervation; D014110:Touch / Q000502:physiology*
keywords: C Tactile; Erotic; Periphery; Pleasantness; Somatosensory; Touch