Electrical stimulation for inducing muscle contraction can be divided into peripheral nerve stimulation (PNS) and motor point stimulation (MPS). Although the neural pathways activated by PNS have been well studied, those by MPS are still unclear. Here we investigated whether MPS activates Ia-sensory nerves and induces antidromic firing of motor nerves. Ten able-bodied males and females participated in this study. We confirmed that soleus MPS did not induce the H-reflex while soleus PNS did. Furthermore, MPS of the tibialis anterior muscle did not induce the reciprocal inhibition of soleus muscle while PNS did. For testing the effect of MPS on motor neuron excitability, we examined the H-reflex modulation by soleus MPS. When the conditioning and test interval was under 100-ms and the conditioning stimulus intensity was above 30-mA, soleus MPS induced the H-reflex inhibition. This suggests that soleus MPS produces antidromic firing that can induce after-hyperpolarization. These results suggest that MPS predominantly activates the motor nerve without depolarizing the Ia-sensory nerve. Since MPS is applicable to larger number of muscles compared to PNS, utilizing MPS can lead to more versatile neuromodulation of the spinal cord.

诱导肌肉收缩的电刺激可分为周围神经刺激（PNS）和运动点刺激（MPS）。尽管已经对PNS激活的神经通路进行了深入研究，但MPS激活的神经通路仍不清楚。在这里，我们研究了MPS是否激活Ia感觉神经并诱导运动神经的反刺激放电。十名身体强壮的男性和女性参加了这项研究。我们确认比目鱼眼神经系统并没有诱导比目鱼眼神经系统的H反射。此外，胫前肌的MPS不会引起比目鱼肌的相互抑制，而PNS却会。为了测试MPS对运动神经元兴奋性的影响，我们检查了比目鱼MPS对H-反射的调节作用。当调节和测试间隔低于100毫秒且调节刺激强度高于30毫安时，比目鱼MPS诱导H反射抑制。这表明比目鱼MPS产生了反皮肤的放电，可以诱发超极化后。这些结果表明，MPS主要激活运动神经而不会使Ia感觉神经消极化。与PNS相比，由于MPS适用于更多的肌肉，因此利用MPS可以导致脊髓更广泛的神经调节。