title: Somatosensory evoked high frequency oscillations recorded from subdural electrodes.
abstract: OBJECTIVE
  To examine high frequency oscillations (HFOs) of somatosensory evoked potentials (SEPs) recorded directly from subdural electrodes to investigate the relationship between the primary somatosensory cortex and HFOs.
  
  
  METHODS
  SEPs were recorded directly from subdural electrodes previously implanted in 3 patients for clinical evaluation prior to surgical treatment of intractable epilepsy.
  
  
  RESULTS
  The primary sensory cortex (area 3b) was proposed as the source of somatosensory HFOs, because the distribution of HFOs recorded from the subdural electrodes agreed with the distribution of the N20-P20 components of the somatosensory evoked potential. The somatosensory HFOs showed a strictly somatotopic source arrangement. There was a polarity inversion of the prophase component and also the N20-P20 component of HFOs across the central sulcus. However, the phase was synchronized in the latter part of the HFOs.
  
  
  CONCLUSIONS
  We propose that the origins of the early and latter parts of HFOs are different, and that there was a clear somatotopy.
authors.affiliation: Department of Neurology, School of Medicine, University of Occupational and Environmental Health, City 807-8555, Kitakyusyu, Japan. yukiyuki@xf6.so-net.ne.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Kojima
authors.forename: T
authors.initials: T
authors.lastname: Uozumi
authors.forename: N
authors.initials: N
authors.lastname: Akamatsu
authors.forename: K
authors.initials: K
authors.lastname: Matsunaga
authors.forename: E
authors.initials: E
authors.lastname: Urasaki
authors.forename: S
authors.initials: S
authors.lastname: Tsuji
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D017029:Epilepsy, Complex Partial / Q000503:physiopathology*; D005073:Evoked Potentials, Somatosensory; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D009044:Motor Cortex / Q000503:physiopathology; D009991:Oscillometry; D011930:Reaction Time; D013003:Somatosensory Cortex / Q000503:physiopathology; D013355:Subdural Space / Q000503:physiopathology*; D014459:Ulnar Nerve / Q000503:physiopathology