Operant Conditioning of a Spinal Reflex Can Improve Locomotion after Spinal Cord Injury in Humans

The Journal of Neuroscience, 2013 · DOI: 10.1523/JNEUROSCI.3968-12.2013 · Published: February 6, 2013

Spinal Cord Injury Neurology Rehabilitation

Simple Explanation

This study explores whether people with spinal cord injuries can improve their walking by learning to control a specific spinal reflex (the soleus H-reflex). Participants tried to decrease the size of their H-reflex through training. Some participants received feedback to help them control the reflex, while others did not. Researchers then measured changes in walking speed, symmetry, and muscle activity. The results suggest that people with SCI can learn to control this spinal reflex, and that doing so can lead to improvements in walking ability.

Study Duration

3 Months

Participants

13 ambulatory subjects with SCI

Evidence Level

Level 2; Experimental study

Key Findings

1
People with incomplete SCI can learn to decrease the size of their soleus H-reflex through operant conditioning.
2
Decreasing the H-reflex was associated with faster and more symmetrical walking in the participants.
3
Participants who successfully decreased their H-reflex also showed improved muscle activity patterns during walking and reported feeling improvements in their daily lives.

Research Summary

The study investigated the effect of operant conditioning of the soleus H-reflex on locomotion in individuals with chronic incomplete spinal cord injury. Participants were divided into down-conditioning (DC) and unconditioned (UC) groups. The DC group underwent 30 sessions of H-reflex down-conditioning, while the UC group had their H-reflex simply measured. Locomotion was assessed before and after the sessions. The results showed that successful H-reflex down-conditioning was associated with improvements in walking speed, symmetry, and muscle activity modulation, suggesting that this approach could enhance recovery of function after SCI.

Practical Implications

Targeted Rehabilitation

Reflex-conditioning protocols can be designed to address each individual’s particular deficits by targeting specific spinal pathways.

Complementary Therapy

Reflex-conditioning protocols might supplement therapies that involve repetition of complex behaviors, such as treadmill training.

Broader Applications

Reflex conditioning may also prove useful for disorders in which the CST is not affected, such as peripheral nerve injuries.

Study Limitations

1
The study population was limited to individuals with incomplete SCI (AIS C or D).
2
The dependence of reflex conditioning on the CST may affect its efficacy in people with more severe impairments.
3
Further research is needed to determine the long-term effects of H-reflex conditioning.

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