title: Differential modulation of the short- and long-latency somatosensory evoked potentials in a forewarned reaction time task.
abstract: OBJECTIVE
  We investigated modulation of the short- and long-latency somatosensory evoked potentials (SEPs) in a forewarned reaction time task.
  
  
  METHODS
  A pair of warning (auditory) and imperative stimuli (somatosensory) was presented with a 2 s interstimulus interval. In movement condition, subjects responded by grip movement with the ipsilateral hand to the somatosensory stimulation when the imperative stimulus was presented. In counting condition, they silently counted the number of imperative stimuli. The SEPs in response to the imperative stimuli were recorded.
  
  
  RESULTS
  Frontal N30 and central N60 amplitudes were significantly smaller in the movement than in the counting or rest conditions. None of the short-latency components differed between the counting and rest conditions. In contrast to the short-latency components, P80 was significantly larger in the counting than in the rest condition, and showed a further increase from the counting to the movement condition. The N140 amplitude was significantly larger in the movement than the rest condition, but was not changed between the counting and the rest conditions.
  
  
  CONCLUSIONS
  The attenuation of the frontal N30 and central N60, and the enhancement of the P80 and possibly the N140 resulted from the centrifugal mechanism. The present findings may show the different effects of voluntary movement on the early and subsequent cortical processing of the relevant somatosensory information requiring a behavioral response.
  
  
  CONCLUSIONS
  The present study demonstrated the differential modulation of short- and long-latency components of SEPs in a forewarned reaction time task.
authors.affiliation: Doctoral program in Health and Sports Sciences, University of Tsukuba, Tsukuba, Japan. nikita@seiri.taiiku.tsukuba.ac.jp
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kida
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Nishihira
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Wasaka
authors.forename: Yukie
authors.initials: Y
authors.lastname: Sakajiri
authors.forename: Toshiki
authors.initials: T
authors.lastname: Tazoe
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D003463:Cues; D004558:Electric Stimulation; D004569:Electroencephalography; D004576:Electromyography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*