Cortical Brain Activation During Robot‐Assisted Gait in Humans With Acute and Chronic Spinal Cord Injury: A Functional Near‐Infrared Spectroscopy Study

TL;DR

This study uses brain imaging to explore how people with spinal cord injuries use their brain's motor areas during robot-assisted walking, showing brain adaptability.

Contribution

The study demonstrates brain motor cortex plasticity in individuals with spinal cord injury during robotic gait training.

Findings

Chronic SCI patients showed higher brain activity in motor areas compared to acute patients during robotic gait.

Paraplegic individuals exhibited greater motor cortex activation than tetraplegic individuals during the task.

Brain motor areas like SMA and M1 showed increased activity during robotic gait compared to rest.

Abstract

Most treatments being developed to regain motor function following spinal cord injury (SCI) presuppose that brain motor functions remain intact. To examine this assumption, this study aims to analyze residual neurological functions during assisted robotic gait in individuals with SCI comparing blocks (gait × resting), time after SCI (acute × chronic), injury level (paraplegic × tetraplegic), and ASIA scale (ASIA C × D). The hemodynamic functions were analyzed using functional near‐infrared spectroscopy (fNIRS) in 23 individuals (11 acute, 12 chronic; ASIA Impairment Scale grade C: 10, D: 13; paraplegia: 15, tetraplegia: 8) while performing an assisted robotic gait task (Lokomat). Brain areas analyzed included supplementary motor area (SMA), dorsolateral prefrontal cortex (DLPFC), primary motor cortex (M1), and primary somatosensory cortex (S1). Blocks (robotic gait × resting), acute × chronic, paraplegic × tetraplegic, and ASIA C × ASIA D groups were compared. For the block comparison, there was a significant difference in SMA and M1, with higher oxyhemoglobin values in the robotic gait task compared to resting. For the comparison between groups, there was a significant difference in M1, with higher oxyhemoglobin values in the chronic group compared to the acute group. The individuals with paraplegia exhibited greater activity in M1 than those with tetraplegia during the robotic gait task. These results demonstrate the plasticity and adaptability of brain motor cortex areas even during the chronic phase after SCI. The brain motor cortex activity during a walking motor task reinforces the importance of analyzing residual neurological function after SCI.

Panel (A) shows the experimental setup, illustrating the positioning of the individual with spinal cord injury within the robotic gait device. Panel (B) presents the experimental flowchart. Panel (C) shows the mean values (standard deviation) of the hemodynamic response to oxygenated hemoglobin in the supplementary motor area (SMA), dorsolateral prefrontal cortex (DLPFC), primary motor cortex (M1), and primary somatosensory cortex (S1) for the robotic gait (black) and resting (red) blocks.

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