Cortical neuroprosthesis-mediated functional ipsilateral control of locomotion in rats with spinal cord hemisection

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.

Spinal Cord Injury-Induced Changes in Encoding and Decoding of Bipedal Walking by Motor Cortical Ensembles

“…The function and the role of the unilateral motor cortex for contralateral and ipsilesional limbs in the motor recovery after SCI remain controversial [28][29][30][31][32][33]. Although cortical stimulation predominantly recruits contralateral muscle contraction, there is limited evidence showing that cortical stimulation could also mediate ipsilateral muscle contraction after SCI [34]. More, there are numerous neuroengineering studies using the unilateral cortical response to predict bilateral hindlimb movements, such as kinematic parameters and various EMGs signals [23,35,36].…”