title: Increased gamma-range activity in human sensorimotor cortex during performance of visuomotor tasks.
abstract: OBJECTIVE
  We documented changes in spectral power of human electrocorticograms (ECoG) during performance of sensorimotor tasks.
  
  
  METHODS
  In 6 human subjects, ECoGs were recorded simultaneously from 14 subdural cortical sites in forearm sensorimotor cortex. The subjects performed 3 visuomotor tasks: tracking a moving visual target with a joystick-controlled cursor, threading pieces of tubing, and pinching the fingers sequentially against the thumb. Control conditions consisted of passive resting and active extension of the wrist. For each site the spectral power of the ECoG during these behaviors was computed for 5 10 Hz ranges between 10 and 60 Hz.
  
  
  RESULTS
  All subjects showed power decreases in the range of 11-20 Hz and power increases in the 31-60 Hz range during performance of the visuomotor tasks, at sites in forearm sensorimotor cortex and adjacent areas. Simple wrist movements often produced little change in power. Three subjects showed episodes of explicit gamma oscillations during the visuomotor tasks. Different sites showed increases in gamma-range power for different tasks, indicating that the spatial distribution of the gamma activity is specific to the tasks. Cross-spectra showed that gamma activity could become synchronized between separate sites during particular tasks.
  
  
  CONCLUSIONS
  Synchronized gamma-range activity in human sensorimotor cortex increases with performance of manipulative visuomotor tasks, supporting the hypothesis that coherent gamma oscillations may play a role in sensorimotor integration or attention.
authors.affiliation: Department of Physiology and Biophysics, University of Washington, Seattle 98195, USA.
authors.forename: F
authors.initials: F
authors.lastname: Aoki
authors.forename: E E
authors.initials: EE
authors.lastname: Fetz
authors.forename: L
authors.initials: L
authors.lastname: Shupe
authors.forename: E
authors.initials: E
authors.lastname: Lettich
authors.forename: G A
authors.initials: GA
authors.lastname: Ojemann
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002648:Child; D004569:Electroencephalography / Q000379:methods; D004827:Epilepsy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D013003:Somatosensory Cortex / Q000503:physiopathology*; D013647:Task Performance and Analysis