Related Experiment Videos
Long-loop reflex from arm afferents to remote muscles in normal man
Yasuhiro Kagamihara1, Akito Hayashi, Yoshihisa Masakado
1Department of Neurology, Tokyo Metropolitan Neurological Hospital, Musashidai 2-6-1, Fuchu City, 183-0042, Tokyo, Japan. ykagami@tmnh.fuchu.tokyo.jp
Experimental Brain Research
|May 14, 2003
Summary
Median nerve stimulation influences remote muscles through long-loop reflexes, not spinal pathways. Soleus H-reflex facilitation is linked to reduced presynaptic inhibition.
Area of Science:
- Neuroscience
- Motor Control
Background:
- Understanding how neural pathways mediate responses in remote muscles is crucial for motor control research.
- The role of the median nerve in modulating spinal motoneurones in distant muscles requires further investigation.
Purpose of the Study:
- To investigate the effects of median nerve stimulation on motoneurones of remote muscles in healthy subjects.
- To differentiate between spinal and supraspinal pathways involved in median nerve-induced reflexes.
Main Methods:
- Utilized H-reflex, averaged electromyography (EMG), and post-stimulus time histogram (PSTH) techniques.
- Applied median nerve stimulation and recorded responses in various muscles, including soleus, masseter, and limb muscles.
Main Results:
- Median nerve stimulation facilitated the soleus H-reflex, peaking at 100 ms, mediated by cutaneous afferents.
- Inhibition, rather than facilitation, was observed in most remote muscles, with latency varying by muscle location (rostral to caudal).
- Facilitation of the soleus H-reflex was primarily attributed to decreased presynaptic inhibition.
Conclusions:
- Median nerve stimulation elicits long-loop reflexes, ascending to the brainstem and descending, rather than purely propriospinal interlimb reflexes.
- The observed inhibition patterns suggest a supraspinal pathway, potentially involving the pons.
- Differential effects on H-reflex and motor units highlight the complexity of median nerve's influence on motoneurones.