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Effects of H-reflex conditioning upon the contralateral alpha motoneuron pool
Electroencephalography and Clinical Neurophysiology
|January 1, 1979
Summary
This study found that stimulating one leg's tibial nerve can facilitate the H-reflex in the other leg's soleus muscle, suggesting bilateral reflex pathways. This bilateral facilitation is likely due to stimulus-evoked inputs, not muscle twitches.
Area of Science:
- Neuroscience
- Motor Control
- Human Physiology
Background:
- The H-reflex is a measure of spinal cord reflex excitability.
- Previous studies suggest long-loop reflexes may have bilateral influences.
- Understanding motoneuron pool excitability is crucial for motor control research.
Purpose of the Study:
- To investigate the bilateral nature of H-reflex recovery curves.
- To determine the origin of late facilitation in the soleus motoneuron pool.
- To explore the role of stimulus-evoked versus twitch-evoked inputs in reflex modulation.
Main Methods:
- Eliciting H-reflex recovery curves using subliminal conditioning stimuli.
- Stimulation of ipsilateral and contralateral posterior tibial nerves.
- Recruitment of 10 healthy female subjects for the study.
Main Results:
- A distinct period of facilitation was observed in the ipsilateral soleus motoneuron pool.
- This facilitation occurred 75-250 msec after conditioning stimulus application.
- Evidence suggests the facilitation is bilateral and likely stimulus-evoked.
Conclusions:
- The study provides evidence for bilateral facilitation of the soleus motoneuron pool.
- Results support the hypothesis of stimulus-evoked inputs, potentially from descending long-loop reflexes.
- Further research is needed to definitively rule out cutaneous afferent involvement in late facilitation.