Abstract
AbstractRecent studies in monkeys showed that when the direct cortico-motoneuronal connection was transected at mid-cervical segments, remaining, indirect cortico-motoneuronal pathways compensated for finger dexterity within one to three months. To elucidate the changes in dynamic properties of neural circuits during the recovery, we investigated the cortico-muscular and inter-muscular couplings of activities throughout the recovery course. Activities of antagonist muscle pairs showed co-activation during the second postoperative week, and oscillated coherently at frequencies of 30-46 Hz (gamma-band) by one month postoperatively. Such gamma-band inter-muscular coherence was not observed preoperatively, but became prominent and distributed widely over proximal and distal muscles with the recovery. Neither the gamma-band cortico-muscular coupling (14-30 Hz) observed before lesion, nor a gamma-band oscillation was observed in bilateral motor cortex after lesion. Thus, we propose that an unknown, subcortical oscillator, independent of cortical oscillation, commonly recruits hand/arm muscles and may underlie functional recovery of dexterous finger movements.
Highlights
Understanding the neural mechanisms of functional recovery after partial lesion of the central nervous system will contribute to establishing a roadmap of neuro-rehabilitational therapy for patients with brain damage or spinal cord injury
We demonstrated a time-dependent change in activation of cortical networks during the functional recovery of finger dexterity after lesion of the l-CST3
It was proposed that such cortico-muscular coupling is mediated by the monosynaptic CM pathway, which has a pronounced influence over distal limb function[9,10]
Summary
Understanding the neural mechanisms of functional recovery after partial lesion of the central nervous system will contribute to establishing a roadmap of neuro-rehabilitational therapy for patients with brain damage or spinal cord injury. The macaque monkey models of brain/spinal cord injury are valuable because the structures of the macaque CNS and motor apparatus are similar to those of human[1] In these monkeys, the dexterity of finger movements, such as precision grip and independency of individual fingers, recovers within one to three months after lesion of the lateral corticospinal tract (l-CST) at the C4/C5 cervical spinal segments[2,3]. The dexterity of finger movements, such as precision grip and independency of individual fingers, recovers within one to three months after lesion of the lateral corticospinal tract (l-CST) at the C4/C5 cervical spinal segments[2,3] Based on this finding, it was postulated that functions of the direct cortico-motoneuronal (CM) pathway might be taken over by remaining neuronal pathways, presumably mediated by propriospinal and/or reticulospinal neurons[2,3,4,5,6]. To characterize changes in the dynamic properties of neural networks connecting the motor cortices and hand/arm muscles, we simultaneously recorded local field potentials (LFPs) in bilateral M1 and electromyography (EMG) of various hand/arm muscles in two monkeys, and analyzed the cortico-muscular and inter-muscular couplings during a force tracking, precision grip task both before spinal cord lesion and during the recovery course
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
