title: Pre-movement modulation of tibial nerve SEPs caused by a self-initiated dorsiflexion.
abstract: OBJECTIVE
  To investigate the centrifugal effect on somatosensory evoked potentials (SEPs), we recorded the pre-movement modulation of SEPs following stimulation of the tibial nerve caused by a self-initiated dorsiflexion.
  
  
  METHODS
  SEPs following stimulation of the right tibial nerve at the popliteal fossa were recorded during self-initiated dorsiflexion of the right ankle every 5-7s. Based on the onset of Bereitschaftspotential and negative slope, the preparatory period before dorsiflexion was divided into four sub-periods (pre-BP, BP1a, BP1b and BP2 sub-period), and SEPs in each sub-period were averaged. SEPs were also recorded in a stationary condition.
  
  
  RESULTS
  P30, N40, P50 and N70 were identified at Cz in all subjects. The amplitude of P30 was significantly smaller in the BP2 sub-period than in the pre-BP sub-period. The N40 amplitude was significantly attenuated in the BP2 sub-period compared with the stationary condition, the pre-BP sub-period, the BP1a sub-period and the BP1b sub-period.
  
  
  CONCLUSIONS
  These results suggested that the motor-related areas involved in generating negative slope modulated the tibial nerve SEPs preceding a self-initiated contraction of the agonist muscle.
  
  
  CONCLUSIONS
  The centrifugal gating effect on SEPs extends to the somatosensory information from the antagonistic body part.
authors.affiliation: Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8585, Japan. wasaka@nips.ac.jp
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Wasaka
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kida
authors.forename: Hiroki
authors.initials: H
authors.lastname: Nakata
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Kakigi
mesh_terms: D000328:Adult; D000842:Ankle / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D004569:Electroencephalography; D004576:Electromyography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology*; D013979:Tibial Nerve / Q000502:physiology*; D014836:Volition / Q000502:physiology*