Novel and Direct Access to the Human Locomotor Spinal Circuitry

The Journal of Neuroscience, 2010 · DOI: 10.1523/JNEUROSCI.4751-09.2010 · Published: March 10, 2010

Spinal Cord Injury Neurology Rehabilitation

Simple Explanation

This study explores whether spinal electromagnetic stimulation (SEMS) can activate the spinal locomotor circuitry in humans, potentially helping individuals recover locomotion after spinal cord injury. The researchers found that SEMS at specific frequencies and intensities induced involuntary, rhythmic leg movements in participants placed in a gravity-neutral position, suggesting direct activation of spinal cord circuitry. Combining SEMS with muscle vibration further enhanced locomotor-like activity, indicating a potential synergistic effect for rehabilitation purposes.

Study Duration

Not specified

Participants

65 students

Evidence Level

Not specified

Key Findings

1
SEMS at the T11-T12 vertebrae induced involuntary bilateral locomotor-like movements in the legs of individuals.
2
The latency of locomotor-like activity during SEMS was rapid (0.68 ± 0.1 s), suggesting direct activation of spinal circuitry.
3
Combining SEMS with vibration of leg muscles was more effective in facilitating locomotor-like activity than SEMS alone.

Research Summary

This study demonstrates the feasibility of using SEMS to induce locomotor-like movements in non-injured individuals, providing a novel noninvasive approach to access the human locomotor spinal circuitry. SEMS appears to directly activate the spinal locomotor circuitry, as indicated by the immediate response and the absence of strictly time-linked responses within the EMG bursts. The combination of SEMS and muscle vibration synergistically enhances locomotor-like activity, suggesting a potential strategy for improving rehabilitation outcomes.

Practical Implications

Rehabilitation Tool

SEMS could be developed as a noninvasive clinical tool to rehabilitate individuals with spinal cord injuries.

Diagnostic Tool

SEMS can potentially assess the potential of an individual to recover locomotion after a spinal cord injury.

Understanding Locomotion

The study provides insights into the neural mechanisms underlying human locomotion and the role of spinal circuitry.

Study Limitations

1
Subject selectivity in locomotor responses to SEMS or vibration was observed, which could be due to different levels of supraspinally mediated inhibition of the spinal circuitry from subject to subject.
2
The study did not fully explore the mechanistic differences in stimulation frequency responses between SEMS and epidural stimulation.
3
The experiments were not designed to definitively address the presence of central pattern generation in the human spinal cord.

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