title: The effect of water immersion on short-latency somatosensory evoked potentials in human.
abstract: BACKGROUND
  Water immersion therapy is used to treat a variety of cardiovascular, respiratory, and orthopedic conditions. It can also benefit some neurological patients, although little is known about the effects of water immersion on neural activity, including somatosensory processing. To this end, we examined the effect of water immersion on short-latency somatosensory evoked potentials (SEPs) elicited by median nerve stimuli. Short-latency SEP recordings were obtained for ten healthy male volunteers at rest in or out of water at 30 °C. Recordings were obtained from nine scalp electrodes according to the 10-20 system. The right median nerve at the wrist was electrically stimulated with the stimulus duration of 0.2 ms at 3 Hz. The intensity of the stimulus was fixed at approximately three times the sensory threshold.
  
  
  RESULTS
  Water immersion significantly reduced the amplitudes of the short-latency SEP components P25 and P45 measured from electrodes over the parietal region and the P45 measured by central region.
  
  
  CONCLUSIONS
  Water immersion reduced short-latency SEP components known to originate in several cortical areas. Attenuation of short-latency SEPs suggests that water immersion influences the cortical processing of somatosensory inputs. Modulation of cortical processing may contribute to the beneficial effects of aquatic therapy.
  
  
  BACKGROUND
  UMIN-CTR (UMIN000006492).
authors.affiliation: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Shimami- cho 1398, kita-ku, Niigata city, Japan. daisuke@nuhw.ac.jp
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sato
authors.forename: Koya
authors.initials: K
authors.lastname: Yamashiro
authors.forename: Hideaki
authors.initials: H
authors.lastname: Onishi
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Shimoyama
authors.forename: Takuya
authors.initials: T
authors.lastname: Yoshida
authors.forename: Atsuo
authors.initials: A
authors.lastname: Maruyama
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004558:Electric Stimulation; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D006801:Humans; D007101:Immersion; D008297:Male; D008475:Median Nerve / Q000502:physiology; D010812:Physical Stimulation; D011930:Reaction Time / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology*; D014867:Water; D055815:Young Adult
chemical_list: D014867:Water