Johansson H, Sjölander P, Sojka P
Department of Physiology, University of Umeå, Sweden.
J Physiol (Paris). 1991;85(1):6-19.
The experiments were performed on 21 cats anaesthetized with alpha-chloralose. The aim of the study was to investigate sets of simultaneously recorded spindle afferents (2-4 in each set) from the triceps surae muscle (GS) with respect to the pattern of fusimotor reflex effects evoked by different types of ipsi- and contralateral reflex stimulation. The afferents' responses to sinusoidal stretching of the GS muscle were determined and the fusimotor reflex effects were assessed by comparing the afferent responses (i.e. the mean rate of firing and the depth of modulation) elicited during reflex stimulation with those evoked in absence of any reflex stimulus. Natural of electrical activations of ipsi- and contralateral muscle, skin and joint receptor afferents were used as reflex stimuli. The spindle afferents were influenced by several modalities and from wide areas, with a majority responding to both ipsi- and contralateral stimuli. A particular reflex stimulus often caused different effects on different afferents, and the various reflex stimuli seldom gave similar effects on a particular afferent. Multivariate analysis revealed that the variation in response profiles among simultaneously recorded afferents were as great as between afferents recorded on different occasions. This suggests that the individualized response prifiles, observed in earlier investigations, represent a very diversified reflex control of the spindle primary afferents, and are not a reflection of changes in the setting of the spinal interneuronal network, occurring during the time interval between the recordings of different units. Also, there was no relation between the conduction velocity of the afferents and the reflex profiles of the afferents, but non-linear relations were found between effects elicited by different types of stimuli. Indications were also found that it may be possible to separate the population of GS muscle spindles into subgroups, according to the fusimotor effects exhibited by activation of various categories of ipsi- and contralateral receptor afferents. It is concluded that one possible way of making the very complex reflex system controlling the muscle spindles intelligible may be a combination of multiple simultaneous recordings of spindle afferents and multivariate analysis.
实验在21只用α-氯醛糖麻醉的猫身上进行。本研究的目的是研究从腓肠肌（GS）同时记录的每组2 - 4条梭内传入纤维，观察不同类型同侧和对侧反射刺激所诱发的融合运动反射效应模式。测定传入纤维对GS肌肉正弦拉伸的反应，并通过比较反射刺激期间引发的传入反应（即平均放电频率和调制深度）与无任何反射刺激时诱发的反应来评估融合运动反射效应。同侧和对侧肌肉、皮肤及关节感受器传入纤维的自然或电激活用作反射刺激。梭内传入纤维受到多种方式和广泛区域的影响，大多数对同侧和对侧刺激均有反应。特定的反射刺激通常对不同的传入纤维产生不同的影响，而各种反射刺激很少对特定的传入纤维产生相似的影响。多变量分析显示，同时记录的传入纤维之间反应模式的差异与不同时间记录的传入纤维之间的差异一样大。这表明，早期研究中观察到的个体化反应模式代表了对梭内初级传入纤维非常多样化的反射控制，而不是脊髓中间神经元网络设置在不同单位记录时间间隔内发生变化的反映。此外，传入纤维的传导速度与传入纤维的反射模式之间没有关系，但发现不同类型刺激所引发的效应之间存在非线性关系。还发现有迹象表明，根据不同类别同侧和对侧感受器传入纤维激活所表现出的融合运动效应，有可能将GS肌梭群体分为亚组。得出的结论是，使控制肌梭的非常复杂的反射系统变得易于理解的一种可能方法可能是同时对梭内传入纤维进行多次记录并结合多变量分析。
