title: Habituation to experimentally induced electrical pain during voluntary-breathing controlled electrical stimulation (BreEStim).
abstract: OBJECTIVE
  Painful peripheral electrical stimulation to acupuncture points was found to cause sensitization if delivered randomly (EStim), but induced habituation if triggered by voluntary breathing (BreEStim). The objective was to systematically compare the effectiveness of BreEStim and EStim and to investigate the possible mechanisms mediating the habituation effect of BreEStim.
  
  
  METHODS
  Eleven pain-free, healthy subjects (6 males, 5 females) participated in the study. Each subject received the BreEStim and EStim treatments in a random order at least three days apart. Both treatments consisted of 120 painful but tolerable stimuli to the ulnar nerve at the elbow on the dominant arm. BreEStim was triggered by voluntary breathing while EStim was delivered randomly. Electrical sensation threshold (EST) and electrical pain threshold (EPT) were measured from the thenar and hypothenar eminences on both hands at pre-intervention and 10-minutes post-intervention.
  
  
  RESULTS
  There was no difference in the pre-intervention baseline measurement of EST and EPT between BreEStim and EStim. BreEStim increased EPT in all tested sites on both hands, while EStim increased EPT in the dominant hypothenar eminence distal to the stimulating site and had no effect on EPT in other sites. There was no difference in the intensity of electrical stimulation between EStim and BreEStim.
  
  
  CONCLUSIONS
  Our findings support the important role human voluntary breathing plays in the systemic habituation effect of BreEStim to peripheral painful electrical stimulation.
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, Houston, Texas, United States of America; Neurorehabilitation Research Laboratory TIRR Memorial Hermann Research Center, Houston, Texas, United States of America.
authors.forename: Shengai
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, Houston, Texas, United States of America; Neurorehabilitation Research Laboratory TIRR Memorial Hermann Research Center, Houston, Texas, United States of America.
authors.forename: Tracy
authors.initials: T
authors.lastname: Hu
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, Houston, Texas, United States of America; Neurorehabilitation Research Laboratory TIRR Memorial Hermann Research Center, Houston, Texas, United States of America.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Beran
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, Houston, Texas, United States of America; Neurorehabilitation Research Laboratory TIRR Memorial Hermann Research Center, Houston, Texas, United States of America.
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
mesh_terms: D015669:Acupuncture Points; D000328:Adult; D004558:Electric Stimulation; D005260:Female; D006185:Habituation, Psychophysiologic; D006801:Humans; D008297:Male; D010146:Pain; D017288:Pain Threshold; D012119:Respiration