title: Decoupling the cortical power spectrum reveals real-time representation of individual finger movements in humans.
abstract: During active movement the electric potentials measured from the surface of the motor cortex exhibit consistent modulation, revealing two distinguishable processes in the power spectrum. At frequencies <40 Hz, narrow-band power decreases occur with movement over widely distributed cortical areas, while at higher frequencies there are spatially more focal power increases. These high-frequency changes have commonly been assumed to reflect synchronous rhythms, analogous to lower-frequency phenomena, but it has recently been proposed that they reflect a broad-band spectral change across the entire spectrum, which could be obscured by synchronous rhythms at low frequencies. In 10 human subjects performing a finger movement task, we demonstrate that a principal component type of decomposition can naively separate low-frequency narrow-band rhythms from an asynchronous, broad-spectral, change at all frequencies between 5 and 200 Hz. This broad-spectral change exhibited spatially discrete representation for individual fingers and reproduced the temporal movement trajectories of different individual fingers.
authors.affiliation: Department of Physics, Seattle Children's Research Institute and Department of Neurological Surgery, University of Washington, Seattle, Washington 98195, USA. kjmiller@u.washington.edu
authors.forename: K J
authors.initials: KJ
authors.lastname: Miller
authors.forename: S
authors.initials: S
authors.lastname: Zanos
authors.forename: E E
authors.initials: EE
authors.lastname: Fetz
authors.forename: M
authors.initials: M
authors.lastname: den Nijs
authors.forename: J G
authors.initials: JG
authors.lastname: Ojemann
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000502:physiology; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D005385:Fingers / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology; D013997:Time Factors; D055815:Young Adult