Abstract
Control of voluntary limb movement is predominantly attributed to the contralateral motor cortex. Nevertheless, increasing evidence suggests the involvement of ipsilateral cortical networks in this process. Ipsilateral control particularly emerges in motor tasks requiring bilateral coordination, which is an essential characteristic of locomotion. Here, we combined a unilateral thoracic spinal cord injury (SCI) with a cortical neuroprosthetic intervention that uncovered a functional role of the ipsilateral cortex in rat movement. In all rats, after SCI, ipsilesional cortex excitation promoted a bilateral synergy, whereby the elevation of the contralateral foot was complemented by ipsilateral hindlimb extension. In two animals, we found that stimulation of a medial cortical sub-region modulated ipsilateral hindlimb flexion. Ipsilateral cortical stimulation delivered after SCI alleviated multiple locomotor and postural deficits. These results establish a causal link between cortical activation and a remarkably fine and proportional ipsilateral control of hindlimb movement, a potential target for future neuroprosthetic technology.
Competing Interest Statement
M.B. and M.M. submitted an international patent application (PCT/CA2020/051047) covering a device allowing performing coherent cortical stimulation during locomotion. They are founders of a company developing a stimulation-based therapy to restore movement after SCI.
Footnotes
I initially forgot to upload the supplementary videos. I only upload these in the revised version.
