Clair J M, Okuma Y, Misiaszek J E, Collins D F
Human Neurophysiology Laboratory, Faculty of Physical Education and Recreation, Centre for Neuroscience, University of Alberta, E-488 Van Vliet Centre, AB, Canada.
Exp Brain Res. 2009 Jun;196(2):217-27. doi: 10.1007/s00221-009-1849-7. Epub 2009 May 30.
Reflex pathways connect all four limbs in humans. Presently, we tested the hypothesis that reflexes also link sensory receptors in the lower leg with muscles of the lower back (erector spinae; ES). Taps were applied to the right Achilles' tendon and electromyographic activity was recorded from the right soleus and bilaterally from ES. Reflexes were compared between sitting and standing and between standing with the eyes open versus closed. Reflexes were evoked bilaterally in ES and consisted of an early latency excitation, a medium latency inhibition, and a longer latency excitation. During sitting but not standing, the early excitation was larger in the ES muscle ipsilateral to the stimulation (iES) than in the contralateral ES (cES). During standing but not sitting, the longer latency excitation in cES was larger than in iES. This response in cES was also larger during standing compared to sitting. Responses were not significantly different between the eyes open and eyes closed conditions. Taps applied to the lateral calcaneus (heel taps) evoked responses in ES that were not significantly different in amplitude or latency than those evoked by tendon taps, despite a 75-94% reduction in the amplitude of the soleus stretch reflex evoked by the heel taps. Electrical stimulation of the sural nerve, a purely cutaneous nerve at the ankle, evoked ES reflexes that were not significantly different in amplitude but had significantly longer latencies than those evoked by the tendon and heel taps. These results support the hypothesis that reflex pathways connect receptors in the lower leg with muscles of the lower back and show that that the amplitude of these reflexes is modulated by task. Responses evoked by stimulation of the sural nerve establish that reflex pathways connect the ES muscles with cutaneous receptors of the foot. In contrast, the large volley in muscle spindle afferents induced by the tendon taps compared to the heel taps did not alter the ES responses, suggesting that the reflex connection between triceps surae muscle spindles and the ES muscles may be relatively weak. These heteronymous reflexes may play a role in stabilizing the trunk for maintaining posture and balance.
反射通路连接人类的四肢。目前，我们检验了这样一个假设：反射也将小腿的感觉感受器与下背部肌肉（竖脊肌；ES）联系起来。轻敲右侧跟腱，并记录右侧比目鱼肌和双侧竖脊肌的肌电图活动。比较了坐姿和站姿之间以及睁眼站立与闭眼站立之间的反射情况。双侧竖脊肌均诱发了反射，包括早期潜伏期兴奋、中期潜伏期抑制和较长潜伏期兴奋。在坐姿而非站姿时，刺激同侧竖脊肌（iES）的早期兴奋大于对侧竖脊肌（cES）。在站姿而非坐姿时，cES中较长潜伏期兴奋大于iES。与坐姿相比，站立时cES中的这种反应也更大。睁眼和闭眼条件下的反应无显著差异。轻敲跟骨外侧（足跟敲击）在竖脊肌中诱发的反应，其幅度和潜伏期与肌腱敲击诱发的反应无显著差异，尽管足跟敲击诱发的比目鱼肌牵张反射幅度降低了75 - 94%。电刺激腓肠神经（踝关节处的纯皮神经）诱发的竖脊肌反射，其幅度无显著差异，但潜伏期明显长于肌腱和足跟敲击诱发的反射。这些结果支持了反射通路将小腿的感受器与下背部肌肉联系起来的假设，并表明这些反射的幅度受任务调制。刺激腓肠神经诱发的反应表明反射通路将竖脊肌与足部的皮肤感受器联系起来。相比之下，与足跟敲击相比，肌腱敲击诱发的肌梭传入纤维的大量放电并未改变竖脊肌的反应，这表明腓肠肌肌梭与竖脊肌之间的反射联系可能相对较弱。这些异源反射可能在稳定躯干以维持姿势和平衡方面发挥作用。
