title: A transcranial direct current stimulation over the sensorimotor cortex modulates the itch sensation induced by histamine.
abstract: OBJECTIVE
  Itching can be suppressed by scratching. However, scratching may aggravate itch symptoms by damaging the skin. Therefore, identifying an alternative approach to suppress itching is of clinical importance. The aim of the present study was to determine whether a transcranial direct current stimulation (tDCS) was useful for itch relief.
  
  
  METHODS
  The present study was performed on a double-blind, Sham-controlled, and cross-over experimental design. A histamine-induced itch was evoked on the left dorsal forearms of healthy participants, who were asked to report the subjective sensation of itching every 30s for 23 min. tDCS was applied over the sensorimotor cortex (SMC) according to a bi-hemispheric stimulation protocol during the itch stimuli; one electrode was placed over the right SMC, while the other was placed over the left SMC. The peak and lasting sensations of itching were compared between R-A/L-C (anodal electrode placed over the right and cathodal electrode over the left), L-A/R-C (anodal electrode placed over the left and cathodal electrode over the right), and Sham interventions.
  
  
  RESULTS
  The peak and lasting itch sensation were significantly suppressed during the R-A/L-C intervention than during the Sham intervention. On the other hand, the L-A/R-C intervention suppressed the peak itch sensation, but the effects did not last for more than a few minutes.
  
  
  CONCLUSIONS
  These results suggest that a bi-hemispheric tDCS intervention, especially when the anodal electrode was placed over the SMC of the contralateral side, was a potentially useful method for relieving lasting itch sensations.
  
  
  CONCLUSIONS
  The present study demonstrated that a tDCS intervention may be an alternative approach for suppressing unpleasant itch sensations in healthy participants. Since tDCS has some advantages, namely, its easy application and safety in a clinical setting, it may become a useful method for the treatment of itching.
authors.affiliation: Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Nakagawa
authors.affiliation: Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan; Department of Dermatology and Temple Itch Center, Temple University School of Medicine, Philadelphia, PA, USA. Electronic address: Hideki.mochizuki@tuhs.temple.edu.
authors.forename: Hideki
authors.initials: H
authors.lastname: Mochizuki
authors.affiliation: Division of Cerebral Integration, Department of Cerebral Research, National Institute for Physiological Sciences, Okazaki, Japan; Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Koyama
authors.affiliation: Laboratory of Psychology, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Division of Cerebral Integration, Department of Cerebral Research, National Institute for Physiological Sciences, Okazaki, Japan; Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sadato
authors.affiliation: Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan; Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan.
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Kakigi
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006632:Histamine / Q000008:administration & dosage* / Q000633:toxicity*; D006801:Humans; D008297:Male; D011537:Pruritus / Q000139:chemically induced* / Q000503:physiopathology / Q000517:prevention & control*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D066191:Sensorimotor Cortex / Q000187:drug effects / Q000502:physiology*; D065908:Transcranial Direct Current Stimulation / Q000379:methods*; D055815:Young Adult
chemical_list: D006632:Histamine
keywords: Histamine; Itch relief; Sensorimotor cortex; Transcranial direct current stimulation (tDCS)