Dietz V, Michel J
Spinal Cord Injury Center, Balgrist University Hospital, Zürich, Switzerland.
Brain. 2008 Dec;131(Pt 12):3421-31. doi: 10.1093/brain/awn263. Epub 2008 Oct 17.
Quadrupedal limb coordination during human walking was recently shown to be upregulated during obstacle stepping. An anticipatory activity of coupled cervico-thoraco-lumbar interneuronal circuits is followed by an appropriate executory activation of leg and arm muscles during task performance. This mechanism was studied in subjects with Parkinson's disease and age-matched controls walking on a treadmill with a randomly approaching obstacle. Spinal reflex (SR) responses, evoked by tibial nerve stimulation during mid-stance, were present in all arm and leg muscles investigated. They were larger before execution of obstacle avoidance compared with normal steps in both subject groups. The performance of obstacle stepping was slightly worse in Parkinson's disease than in control subjects. The anticipatory SR in the arm muscles prior to normal and obstacle steps was larger in Parkinson's disease compared with age-matched subjects, but smaller in the tibialis anterior. The arm and leg muscle activation was stronger during obstacle compared with normal swing but did not differ between Parkinson's disease and age-matched subjects. These observations indicate that quadrupedal limb coordination is basically preserved in Parkinson's disease subjects. Our data are consistent with the proposal that in Parkinson's disease subjects the enhanced anticipatory spinal neuronal activity (reflected in the SR) in the arm muscles is required to achieve an appropriate muscle activation for the automatic control of body equilibrium during the performance of the task. In the tibialis anterior the SR is attenuated presumably because of a stronger voluntary (i.e. cortical) control of leg movements.
最近研究表明，人类行走过程中的四足肢体协调性在跨越障碍物时会增强。在执行任务期间，颈胸腰段中间神经元回路的预期活动之后会伴随腿部和手臂肌肉适当的执行性激活。在帕金森病患者和年龄匹配的对照组在跑步机上行走并随机接近障碍物的过程中对这一机制进行了研究。在所有被研究的手臂和腿部肌肉中，均出现了在站立中期由胫神经刺激诱发的脊髓反射（SR）反应。与两个受试组的正常步幅相比，在执行避障动作之前，这些反应更大。帕金森病患者的避障表现略逊于对照组。与年龄匹配的受试者相比，帕金森病患者在正常步幅和避障步幅之前手臂肌肉中的预期SR更大，但在胫前肌中则较小。与正常摆动相比，在跨越障碍物期间手臂和腿部肌肉的激活更强，但在帕金森病患者和年龄匹配的受试者之间没有差异。这些观察结果表明，帕金森病患者基本保留了四足肢体协调性。我们的数据与以下观点一致：在帕金森病患者中，为了在执行任务期间对身体平衡进行自动控制而实现适当的肌肉激活，需要增强手臂肌肉中预期的脊髓神经元活动（反映在SR中）。在胫前肌中，SR减弱可能是因为对腿部运动有更强的自主（即皮层）控制。
