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bioRxiv · 10.1101/2024.12.09.627519

Soleus H-Reflex Up-Conditioning during Sciatic Nerve Regeneration in Rats Improves Recovery of Locomotion

Chen, Y.·Wang, Y.·Chen, L.·Yang, X.·Gemoets, D. E.·Chen, X. Y.·Wolpaw, J. R.
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Abstract

Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, induces plasticity in the brain and spinal cord that increases (up-conditioning) or decreases (down-conditioning) the reflex elicited by primary afferent input to the spinal motoneuron. In rats in which the sciatic nerve is transected and repaired, soleus (SOL) H-reflex up-conditioning during regeneration strengthens primary afferent reinnervation of SOL motoneurons and improves recovery of the SOL H-reflex. This suggests that H-reflex up-conditioning could improve functional recovery after nerve injury and repair. To explore this possibility, we examined the impact of SOL H-reflex up- or down-conditioning during sciatic regeneration on recovery of locomotor symmetry. Sprague-Dawley rats were implanted with EMG electrodes in right SOL and a stimulating cuff on right posterior tibial nerve. After control data collection, right sciatic nerve was transected and repaired. Control EMG and H-reflex data collection continued for 20 more days. The rat was then exposed for 100 days to either: continued control data collection; SOL H-reflex up-conditioning; or SOL H-reflex down-conditioning. Locomotor EMG, H-reflex, and kinematics were assessed before nerve transection and 120 days after transection. H-reflex up-conditioning improved H-reflex recovery and also restored right/left step symmetry. H-reflex down-conditioning did not worsen H-reflex recovery or right/left step asymmetry. These results suggest that H-reflex up-conditioning might enhance functional recovery after nerve injury in humans. They also confirm previous results indicating that compensatory plasticity prevents inappropriate H-reflex conditioning (i.e., down-conditioning) from further impairing function.

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Chen, Y., Wang, Y., Chen, L., Yang, X., Gemoets, D. E., Chen, X. Y., Wolpaw, J. R.. 2024-12-15. Soleus H-Reflex Up-Conditioning during Sciatic Nerve Regeneration in Rats Improves Recovery of Locomotion. https://doi.org/10.1101/2024.12.09.627519

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