A subcortical oscillatory network contributes to recovery of hand dexterity after spinal cord injury.
Recent studies have shown that after partial spinal-cord lesion at the mid-cervical segment, the remaining pathways compensate for restoring finger dexterity; however, how they control hand/arm muscles has remained unclear. To elucidate the changes in dynamic properties of neural circuits connecting the motor cortex and hand/arm muscles, we investigated the cortico- and inter-muscular couplings of activities throughout the recovery period after the spinal-cord lesion. Activities of antagonist muscle pairs showed co-activation and oscillated coherently at frequencies of 30-46 Hz (gamma-band) by 1-month post-lesion. Such gamma-band inter-muscular coupling was not observed pre-lesion, but emerged and was strengthened and distributed over a wide range of hand/arm muscles along with the recovery. Neither the beta-band (14-30 Hz) cortico-muscular coupling observed pre-lesion nor a gamma-band oscillation was observed in the motor cortex post-lesion. We propose that a subcortical oscillator commonly recruits hand/arm muscles, via remaining pathways such as reticulospinal and/or propriospinal tracts, independent of cortical oscillation, and contributes to functional recovery.
Nishimura
Yukio
Y
Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Japan. yukio@u.washington.edu
Morichika
Yosuke
Y
Isa
Tadashi
T
D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D002540:Cerebral Cortex / Q000503:physiopathology; D004576:Electromyography / Q000379:methods; D005385:Fingers / Q000503:physiopathology; D006225:Hand / Q000503:physiopathology*; D008253:Macaca mulatta; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology; D009434:Neural Pathways / Q000503:physiopathology; D011597:Psychomotor Performance / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000473:pathology / Q000503:physiopathology*