Identifying spinal tracts transmitting distant effects of trans-spinal magnetic stimulation.
Identifying spinal tracts transmitting distant effects of trans-spinal magnetic stimulation.
复制标题
识别传输跨脊髓磁刺激的远距离效应的脊髓束。
DOI：
10.1152/jn.00202.2023
复制
发表时间：
2023
影响因子：
2.5
通讯作者：
Dhaher,YasinY
中科院分区：
文献类型：
--
作者：
Chung,Yu-Chen;Shemmell,Jonathan;Kumala,Caitlin;Soedirdjo,SubaryaniDH;Dhaher,YasinY
估计脊髓运动神经元的特定束输入的状态对于理解神经损伤引起的运动缺陷和潜在的恢复途径至关重要，但对人类来说仍然具有挑战性。在这项研究中，我们探讨了经脊柱磁刺激（TSMS）调节年轻人远端反射回路的能力。 TSMS 应用于胸椎，以调节涉及骶骨水平运动神经元的比目鱼肌 H 反射。相对于周围神经刺激 (PNS)，在 2 至 20 毫秒之间的刺激间隔 (ISI) 处应用低于运动阈值的三个 TSMS 强度。尽管低强度 TSMS 不会对 ISI 中的 H 反射产生任何变化，但两种较高的刺激强度会产生两个阶段的 H 反射抑制：2 至 9 毫秒 ISI 的相对较长持续期，以及 11 至 12 毫秒 ISI 的短相。 2 毫秒 ISI 时的 H 反射抑制独特地依赖于 TSMS 强度。为了确定有助于 H 反射抑制的候选神经通路，我们构建了一个特定束传导时间估计模型。根据我们的模型，11 至 12 毫秒 ISI 时的 H 反射抑制可能是沿外侧网状脊髓束顺向传播的表现。相反，2 毫秒 ISI 的抑制可能反映了沿着感觉纤维的顺向传递，激活到达大脑，然后沿着运动束下降。多种途径可能有助于 4 毫秒和 9 毫秒 ISI 之间的 H 反射调制、沿感觉运动束的顺向传递以及多个运动束的逆向传递。我们的研究结果表明，无创 TSMS 可以影响远端节段的运动神经元兴奋性，并且特定束对运动神经元兴奋性的贡献可以根据传导速度进行区分。新的和值得注意的这项研究探讨了胸椎经脊柱磁刺激 (TSMS) 调节年轻人远端反射回路（涉及骶骨水平运动神经元的 H 反射）的能力。 TSMS 在刺激间期 (ISI) 上诱导 H 反射的两个抑制阶段：2 至 9 毫秒 ISI 的持续时间相对较长，以及 11 至 12 毫秒 ISI 的短阶段。根据特定束传导速度构建的估计概率模型可以识别导致运动神经元兴奋性变化的潜在脊髓束。
Estimating the state of tract-specific inputs to spinal motoneurons is critical to understanding movement deficits induced by neurological injury and potential pathways to recovery but remains challenging in humans. In this study, we explored the capability of trans-spinal magnetic stimulation (TSMS) to modulate distal reflex circuits in young adults. TSMS was applied over the thoracic spine to condition soleus H-reflexes involving sacral-level motoneurons. Three TSMS intensities below the motor threshold were applied at interstimulus intervals (ISIs) between 2 and 20 ms relative to peripheral nerve stimulation (PNS). Although low-intensity TSMS yielded no changes in H-reflexes across ISIs, the two higher stimulus intensities yielded two phases of H-reflex inhibition: a relatively long-lasting period at 2- to 9-ms ISIs, and a short phase at 11- to 12-ms ISIs. H-reflex inhibition at 2-ms ISI was uniquely dependent on TSMS intensity. To identify the candidate neural pathways contributing to H-reflex suppression, we constructed a tract-specific conduction time estimation model. Based upon our model, H-reflex inhibition at 11- to 12-ms ISIs is likely a manifestation of orthodromic transmission along the lateral reticulospinal tract. In contrast, the inhibition at 2-ms ISI likely reflects orthodromic transmission along sensory fibers with activation reaching the brain, before descending along motor tracts. Multiple pathways may contribute to H-reflex modulation between 4- and 9-ms ISIs, orthodromic transmission along sensorimotor tracts, and antidromic transmission of multiple motor tracts. Our findings suggest that noninvasive TSMS can influence motoneuron excitability at distal segments and that the contribution of specific tracts to motoneuron excitability may be distinguishable based on conduction velocities.NEW & NOTEWORTHYThis study explored the capability of trans-spinal magnetic stimulation (TSMS) over the thoracic spine to modulate distal reflex circuits, H-reflexes involving sacral-level motoneurons, in young adults. TSMS induced two inhibition phases of H-reflex across interstimulus intervals (ISIs): a relatively long-lasting period at 2- to 9-ms ISIs, and a short phase at 11- to 12-ms ISIs. An estimated probability model constructed from tract-specific conduction velocities allowed the identification of potential spinal tracts contributing to the changes in motoneuron excitability.