Motor Recovery after Spinal Cord Injury Enhanced by Strengthening Corticospinal Synaptic Transmission

Curr Biol, 2012 · DOI: 10.1016/j.cub.2012.10.046 · Published: December 18, 2012

Spinal Cord Injury Neurology Rehabilitation

Simple Explanation

This study explores a way to improve hand motor function in people with spinal cord injuries (SCI). They focused on strengthening the connections between the brain and spinal cord using a technique called spike timing-dependent plasticity (STDP). By precisely timing the stimulation of brain and peripheral nerves, the researchers were able to enhance the communication between the brain and hand muscles. This improved the voluntary motor output of the hand. The technique involves stimulating the brain (corticospinal volleys) slightly before stimulating the peripheral nerves. This specific timing helps to strengthen the connection between the brain and the muscles, leading to improved hand function.

Study Duration

Not specified

Participants

19 participants with cervical SCI and 14 age-matched healthy controls

Evidence Level

Not specified

Key Findings

1
The study found that when presynaptic volleys arrived before motoneuron discharge, corticospinal transmission and hand voluntary motor output were enhanced in individuals with SCI.
2
Manual dexterity, as measured by the nine-hole peg test, improved after the STDP protocol in participants with SCI.
3
The changes in corticospinal transmission were positively correlated with enhancements in voluntary motor output, suggesting a link between motor output and the induced plasticity.

Research Summary

This study demonstrates spike timing-dependent plasticity of residual corticospinal-motoneuronal synapses in humans with chronic incomplete SCI and shows the functional consequences. The researchers found that specific timing of brain and nerve stimulation enhanced corticospinal transmission, index finger force, and EMG activity in participants with SCI and healthy controls. The study suggests that residual corticospinal-motoneuronal synapses are a potential therapeutic target for enhancing voluntary motor function after SCI.

Practical Implications

Therapeutic Target

Residual corticospinal-motoneuronal synapses can be targeted to enhance voluntary motor function in SCI.

Rehabilitation Strategy

STDP protocols can be developed to improve motor recovery after spinal cord injury.

Clinical Translation

Modulation of corticospinal transmission may be a novel therapeutic avenue for motor disorders.

Study Limitations

1
The study did not record directly at the synapse, relying on electrophysiological measurements to estimate the timing of action potentials.
2
Axonal loss and demyelination after SCI may affect the temporal dispersion of descending volleys.
3
The study acknowledges that other descending or sensory pathways might contribute to the observed results.

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