Noth J, Matthews H R, Friedemann H H
Exp Brain Res. 1984;55(2):317-24. doi: 10.1007/BF00237282.
Reflex stiffness of the flexing human index finger was studied using sinusoidal movements at 3-16 Hz. The Nyquist stiffness diagram indicates the presence of a 'presonance' at around 4 Hz, its 'C' shape after correction for the mechanical properties of the relaxed finger is consistent with the involvement of a stretch reflex in its generation. This contention was supported by the presence of negative friction around 4 Hz and the disappearance of the modulation of the stiffness curve after afferent ischaemic block. Correction for the mechanical properties of active muscle, measured after afferent block, permitted the isolation of the reflex component of stiffness. The circular form of the Nyquist diagram indicates a relatively flat frequency response for the reflex over the range tested, and its radius gives a measure of reflex gain. The low value of the frequency at which the frictional force is minimal, suggests the involvement of a reflex of longer than spinal latency. This is discussed in relation to mechanisms of tremor genesis and the interaction of spinal and long latency reflexes in distal hand muscles.
利用3至16赫兹的正弦运动研究了人类弯曲食指的反射刚度。奈奎斯特刚度图表明在约4赫兹处存在“预共振”，校正放松手指的机械性能后其“C”形与牵张反射参与其产生一致。4赫兹左右存在负摩擦力以及传入性缺血性阻断后刚度曲线调制消失支持了这一论点。校正传入性阻断后测量的主动肌机械性能，使得能够分离出刚度的反射成分。奈奎斯特图的圆形表明在所测试范围内反射具有相对平坦的频率响应，其半径给出了反射增益的度量。摩擦力最小的频率值较低，表明涉及潜伏期长于脊髓潜伏期的反射。这与震颤发生机制以及手部远端肌肉中脊髓反射和长潜伏期反射的相互作用有关进行了讨论。
