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

Area of Science:

• Neuroscience
• Motor Control
• Spinal Cord Injury Research

Background:

• Motor recovery after spinal cord injury (SCI) is task-specific.
• Previous research predominantly used quadrupedal locomotion models.
• Bipedal locomotion offers a more human-relevant paradigm for studying SCI recovery.

Purpose of the Study:

• To investigate spontaneous motor recovery after SCI using a bipedal walking task in non-human primates.
• To analyze neural activity in the primary motor cortex (M1) and its role in motor control post-SCI.
• To explore the potential of M1 in regaining bilateral coordination and enhancing brain-machine interfaces.

Main Methods:

• Two monkeys trained on a bipedal walking task before and after T8 spinal cord hemisection.
• Analysis of single-cell activity in the left primary motor cortex (M1) using information theory.
• Assessment of spontaneous neural and motor recovery without pharmacological intervention.

Main Results:

• Locomotor impairment was more severe on the ipsilateral side compared to the contralateral side.
• Neuronal populations in unilateral M1 increasingly encoded bilateral hindlimb muscle activity during bipedal walking post-SCI.
• Expanded neural information in M1 correlated with more accurate muscle activity control and improved motor recovery.

Conclusions:

• The unilateral primary motor cortex can spontaneously regain control of bilateral coordination after SCI.
• Enhanced neural information processing in M1 contributes to motor recovery and functional improvement.
• These findings suggest potential for improved brain-machine interfaces for SCI rehabilitation.