title: Regulation of motor representation by phase-amplitude coupling in the sensorimotor cortex.
abstract: High-γ amplitude (80-150 Hz) represents motor information, such as movement types, on the sensorimotor cortex. In several cortical areas, high-γ amplitudes are coupled with low-frequency phases, e.g., α and θ (phase-amplitude coupling, PAC). However, such coupling has not been studied in the sensorimotor cortex; thus, its potential functional role has yet to be explored. We investigated PAC of high-γ amplitude in the sensorimotor cortex during waiting for and the execution of movements using electrocorticographic (ECoG) recordings in humans. ECoG signals were recorded from the sensorimotor cortices of 4 epilepsy patients while they performed three different hand movements. A subset of electrodes showed high-γ activity selective to movement type around the timing of motor execution, while the same electrodes showed nonselective high-γ activity during the waiting period (>2 s before execution). Cross frequency coupling analysis revealed that the high-γ amplitude during waiting was strongly coupled with the α phase (10-14 Hz) at the electrodes with movement-selective high-γ amplitudes during execution. This coupling constituted the high-γ amplitude peaking around the trough of the α oscillation, and its strength and phase were not predictive of movement type. As the coupling attenuated toward the timing of motor execution, the high-γ amplitude appeared to be released from the α phase to build a motor representation with phase-independent activity. Our results suggest that PAC modulates motor representation in the sensorimotor cortex by holding and releasing high-γ activity in movement-selective cortical regions.
authors.affiliation: Department of Neurosurgery, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.
authors.forename: Takufumi
authors.initials: T
authors.lastname: Yanagisawa
authors.forename: Okito
authors.initials: O
authors.lastname: Yamashita
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hirata
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Kishima
authors.forename: Youichi
authors.initials: Y
authors.lastname: Saitoh
authors.forename: Tetsu
authors.initials: T
authors.lastname: Goto
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yoshimine
authors.forename: Yukiyasu
authors.initials: Y
authors.lastname: Kamitani
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D003627:Data Interpretation, Statistical; D004562:Electrocardiography; D004827:Epilepsy / Q000503:physiopathology; D005260:Female; D006225:Hand / Q000502:physiology; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology*; D055815:Young Adult