Short-term locomotor adaptation to a robotic ankle exoskeleton does not alter soleus Hoffmann reflex amplitude.
Short-term locomotor adaptation to a robotic ankle exoskeleton does not alter soleus Hoffmann reflex amplitude.
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DOI：
10.1186/1743-0003-7-33
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发表时间：
2010-07-26
影响因子：
5.1
通讯作者：
Ferris DP
中科院分区：
文献类型：
--
作者：
Kao PC;Lewis CL;Ferris DP
为了改善步态康复机器人下肢外骨骼的设计，关键是要确定神经机制，支配运动适应机器人的援助。以前，我们证明了比目鱼肌招募减少了约35%，当步行时，与动力踝关节外骨骼提供足底屈肌扭矩下比目鱼肌比例肌电控制。由于在行走期间比目鱼肌激活的相当大的部分是由牵张反射引起的，因此增加的反射抑制是用于在利用外骨骼辅助行走时减少比目鱼肌募集的一种潜在机制。这是临床相关的，因为许多神经功能受损的人群具有过度活跃的牵张反射，并且减少反射的训练可能导致其运动能力的实质性改善。本研究的目的是量化比目鱼肌霍夫曼（H-）反射反应，在动力与无动力行走。我们测试了比目鱼肌H-反射反应在神经系统完好的受试者（n=8），训练与比目鱼肌控制的机器人踝关节外骨骼行走。在站立中期和后期测试比目鱼H反射，同时受试者在跑步机上以1.25 m/s的速度用外骨骼行走，首先无动力（第一次无动力），然后有动力（有动力），最后再次无动力（第二次无动力）。我们还收集了关节运动学和肌电图。当提供机器人足底屈肌扭矩时，与第一次无动力条件相比，受试者以较低的比目鱼肌肌电图（EMG）激活（27-48%）行走，并伴随H反射振幅降低（12-24%）。在动力行走过程中，H反射幅度与背景比目鱼肌肌电图的比例与两种无动力条件下没有显着差异。这些发现表明，神经系统不会抑制比目鱼肌H反射，以响应对外骨骼辅助的短期适应。未来的研究应该确定这些发现是否也适用于对外骨骼的长期适应。
To improve design of robotic lower limb exoskeletons for gait rehabilitation, it is critical to identify neural mechanisms that govern locomotor adaptation to robotic assistance. Previously, we demonstrated soleus muscle recruitment decreased by ~35% when walking with a pneumatically-powered ankle exoskeleton providing plantar flexor torque under soleus proportional myoelectric control. Since a substantial portion of soleus activation during walking results from the stretch reflex, increased reflex inhibition is one potential mechanism for reducing soleus recruitment when walking with exoskeleton assistance. This is clinically relevant because many neurologically impaired populations have hyperactive stretch reflexes and training to reduce the reflexes could lead to substantial improvements in their motor ability. The purpose of this study was to quantify soleus Hoffmann (H-) reflex responses during powered versus unpowered walking. We tested soleus H-reflex responses in neurologically intact subjects (n=8) that had trained walking with the soleus controlled robotic ankle exoskeleton. Soleus H-reflex was tested at the mid and late stance while subjects walked with the exoskeleton on the treadmill at 1.25 m/s, first without power (first unpowered), then with power (powered), and finally without power again (second unpowered). We also collected joint kinematics and electromyography. When the robotic plantar flexor torque was provided, subjects walked with lower soleus electromyographic (EMG) activation (27-48%) and had concomitant reductions in H-reflex amplitude (12-24%) compared to the first unpowered condition. The H-reflex amplitude in proportion to the background soleus EMG during powered walking was not significantly different from the two unpowered conditions. These findings suggest that the nervous system does not inhibit the soleus H-reflex in response to short-term adaption to exoskeleton assistance. Future studies should determine if the findings also apply to long-term adaption to the exoskeleton.
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影响因子：
2.4
作者：
Gordon, Keith E.;Sawicki, Gregory S.;Ferris, Daniel P.
通讯作者：
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