RECRUITMENT ORDER OF MOTONEURONS IN STRETCH REFLEXES IS HIGHLY CORRELATED WITH THEIR AXONAL CONDUCTION-VELOCITY
RECRUITMENT ORDER OF MOTONEURONS IN STRETCH REFLEXES IS HIGHLY CORRELATED WITH THEIR AXONAL CONDUCTION-VELOCITY
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DOI：
10.1152/jn.1984.52.3.410
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发表时间：
1984-01-01
影响因子：
2.5
通讯作者：
HENNEMAN, E
中科院分区：
文献类型：
--
作者：
BAWA, P;BINDER, MD;HENNEMAN, E
在去大脑猫的牵张反射过程中，对比目鱼肌和内侧腓肠肌（MG）的运动单位进行了成对的研究，以确定它们的募集顺序和轴突传导速度之间的关系。在 97% 的比目鱼肌对中，轴突传导速度较低的运动单位首先被招募。由于比目鱼肌是猫的同质肌肉，运动单位类型的差异并不是有序募集的必要条件，在同质运动单位群体中募集也不是随机的。在内侧腓肠肌（一种异质性肌肉）中，观察到募集序列和传导速度之间具有相同的高度相关性（97%）。因此，决定异质肌肉募集顺序的因素与轴突直径密切相关，就像它们在同质肌肉中一样。将 MG 单元样本中的轴突传导速度与其他研究者研究的 3 个类型识别的 MG 单元样本中的轴突传导速度进行比较表明，运动单元类型并不是控制异质肌肉激活顺序的关键因素。显然，决定牵张反射期间运动神经元放电敏感性的所有突触前和突触后因素的综合作用与其轴突传导速度严格相关。
Motor units of soleus and medial gastrocnemius (MG) muscles were studied in pairs during stretch reflexes in the decerebrate cat to determine the relation between their recruitment orders and axonal conduction velocities. In 97% of soleus pairs, the motor unit with the lower axonal conduction velocity was recruited first. Since the soleus is a homogeneous muscle in the cat, differences in motor-unit type are not a sine qua non for orderly recruitment nor is recruitment random within homogeneous populations of motor units. In the medial gastrocnemius, a heterogeneous muscle, the same high correlation (97%) between recruitment sequence and conduction velocity was observed. Thus, the factors that determine recruitment order in heterogeneous muscles are as closely correlated with axonal diameter as they are in homogeneous muscles. Comparison of axonal conduction velocities in the sample of MG units with those in 3 samples of type-identified MG units studied by other investigators suggests that motor-unit type is not the critical fctor controlling the sequence of activation in heterogeneous muscles. Evidently, the combined effects of all presynaptic and postsynaptic factors that determine susceptibility to discharge in motoneurons during stretch reflexes are strictly correlated with their axonal conduction velocities.