Koç University, School of Medicine, 34450 Sariyer, Istanbul, Turkey.
Koç University, School of Medicine, 34450 Sariyer, Istanbul, Turkey.
J Electromyogr Kinesiol. 2020 Oct;54:102460. doi: 10.1016/j.jelekin.2020.102460. Epub 2020 Aug 29.
Amplitude variation of Hoffmann Reflex (H-reflex) was used as a tool to investigate many neuronal networks. However, H-reflex itself is a subject to intrinsic changes including post-activation depression (P-AD). We aimed to investigate P-AD and its implication on motor control in humans. Upon tibial nerve stimulation in 23 healthy participants, peak-to-peak amplitude change of H-reflex was investigated using surface electromyography (SEMG) of soleus muscle. Variety of stimulus intensities, interstimulus intervals (ISIs), voluntary contraction levels/types and force recording were used to investigate the nature of P-AD. We have shown that P-AD was significantly stronger in the shorter ISIs. The only exception was the ISI of 200 msecs which had a weaker P-AD than some of the longer ISIs. Sudden muscle relaxation, on the other hand, further increased the effectiveness of the ongoing P-AD. Moreover, P-AD displayed its full effect with the first stimulus when there was no muscle contraction and was efficient to reduce the muscle force output by about 30%. These findings provide insight about the variations and mechanism of P-AD and could lead to improvements in diagnostic tools in neurological diseases.
Hoffmann 反射（H 反射）的幅度变化被用作研究许多神经元网络的工具。然而，H 反射本身也会受到内在变化的影响，包括后激活抑制（P-AD）。我们旨在研究 P-AD 及其对人类运动控制的影响。在 23 名健康参与者的胫神经刺激中，使用比目鱼肌的表面肌电图（SEMG）研究 H 反射的峰值到峰值幅度变化。使用各种刺激强度、刺激间隔（ISIs）、自愿收缩水平/类型和力记录来研究 P-AD 的性质。我们已经表明，在较短的 ISIs 中，P-AD 更强。唯一的例外是 200 毫秒的 ISI，它的 P-AD 比一些较长的 ISI 弱。另一方面，肌肉突然放松进一步增加了正在进行的 P-AD 的效果。此外，当没有肌肉收缩时，P-AD 会在第一刺激时发挥其全部作用，并有效地将肌肉力量输出降低约 30%。这些发现提供了关于 P-AD 的变化和机制的深入了解，并可能导致神经疾病诊断工具的改进。
