Traverse Elodie, Brun Clémentine, Harnois Émilie, Mercier Catherine
Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS), Quebec City, QC, Canada.
Faculty of Medicine, Laval University, Québec, QC, Canada.
Neural Plast. 2020 Jul 31;2020:8864407. doi: 10.1155/2020/8864407. eCollection 2020.
Movement is altered by pain, but the underlying mechanisms remain unclear. Assessing corrective muscle responses following mechanical perturbations can help clarify these underlying mechanisms, as these responses involve spinal (short-latency response, 20-50 ms), transcortical (long-latency response, 50-100 ms), and cortical (early voluntary response, 100-150 ms) mechanisms. Pairing mechanical (proprioceptive) perturbations with different conditions of visual feedback can also offer insight into how pain impacts on sensorimotor integration. The general aim of this study was to examine the impact of experimental tonic pain on corrective muscle responses evoked by mechanical and/or visual perturbations in healthy adults. Two sessions (Pain (induced with capsaicin) and No pain) were performed using a robotic exoskeleton combined with a 2D virtual environment. Participants were instructed to maintain their index in a target despite the application of perturbations under four conditions of sensory feedback: (1) proprioceptive only, (2) visuoproprioceptive congruent, (3) visuoproprioceptive incongruent, and (4) visual only. Perturbations were induced in either flexion or extension, with an amplitude of 2 or 3 Nm. Surface electromyography was recorded from Biceps and Triceps muscles. Results demonstrated no significant effect of the type of sensory feedback on corrective muscle responses, no matter whether pain was present or not. When looking at the effect of pain on corrective responses across muscles, a significant interaction was found, but for the early voluntary responses only. These results suggest that the effect of cutaneous tonic pain on motor control arises mainly at the cortical (rather than spinal) level and that proprioception dominates vision for responses to perturbations, even in the presence of pain. The observation of a muscle-specific modulation using a cutaneous pain model highlights the fact that the impacts of pain on the motor system are not only driven by the need to unload structures from which the nociceptive signal is arising.
疼痛会改变运动，但其潜在机制仍不清楚。评估机械扰动后的纠正性肌肉反应有助于阐明这些潜在机制，因为这些反应涉及脊髓（短潜伏期反应，20 - 50毫秒）、经皮质（长潜伏期反应，50 - 100毫秒）和皮质（早期自主反应，100 - 150毫秒）机制。将机械（本体感觉）扰动与不同视觉反馈条件相结合，也能深入了解疼痛如何影响感觉运动整合。本研究的总体目标是检验实验性持续性疼痛对健康成年人中由机械和/或视觉扰动诱发的纠正性肌肉反应的影响。使用机器人外骨骼结合二维虚拟环境进行了两个阶段（疼痛（用辣椒素诱发）和无疼痛）的实验。参与者被要求在四种感觉反馈条件下，尽管受到扰动，仍要将食指保持在目标位置：（1）仅本体感觉，（2）视觉 - 本体感觉一致，（3）视觉 - 本体感觉不一致，（4）仅视觉。在屈曲或伸展方向诱发扰动，幅度为2或3牛米。从肱二头肌和肱三头肌记录表面肌电图。结果表明，无论是否存在疼痛，感觉反馈类型对纠正性肌肉反应均无显著影响。在观察疼痛对不同肌肉纠正反应的影响时，发现了显著的交互作用，但仅针对早期自主反应。这些结果表明，皮肤持续性疼痛对运动控制的影响主要出现在皮质（而非脊髓）水平，并且即使在存在疼痛的情况下，本体感觉在对扰动的反应中也主导着视觉。使用皮肤疼痛模型观察到的肌肉特异性调制突出了这样一个事实，即疼痛对运动系统的影响不仅是由卸载产生伤害性信号的结构的需求所驱动的。
