Schäfer S S
Abteilung Neurophysiologie, Medizinische Hochschule Hannover, Germany.
Exp Brain Res. 1996 Mar;108(2):297-304. doi: 10.1007/BF00228102.
The discharge patterns of primary muscle spindle afferents from the tibial anterior muscle of the cat were recorded under a ramp-and-hold stretch of constant amplitude (7 mm) and stretch rates varying between 1 and 50 mm/s. With seven Ia fibers, the discharge patterns were recorded under various dynamic gamma stimulation frequencies of between 10 and 120 stimuli per second. With 26 passive spindle fibers of the type known as bag1 Ia fibers, the discharge patterns were obtained under progressively increasing prestretch of the muscle. From each discharge pattern the following discharge frequencies were read: the initial activity (the discharge frequency before the start of ramp stretching), the peak dynamic discharge (the discharge frequency at the end of the dynamic phase of stretching), the maximum static value (MSt; the discharge frequency at the beginning of the static phase of stretching), and the final static value (the discharge frequency at the end of the 3rd s of the plateau phase). These four discharge frequency values were plotted against MSt, in separate diagrams for the Ia fibers under dynamic gamma stimulation and for the bag1 Ia fibers. The relationship between the four discharge frequency values and the MSt turned out to be the same-or much the same-for both groups of Ia fibers. This means that the two groups of Ia fibers produced (more or less) identical discharge patterns in response to the ramp-and-hold stretch. In addition, where Ia fibers of the two groups had the same MSt, their dynamic and static responses were determined. Under these circumstances no difference was found in respect to their stretch properties between Ia fibers of dynamically gamma-activated spindles and bag1 Ia fibers of passive spindles. In the Discussion, the high degree of similarity in the behavior of the two groups of Ia fibers is explained in terms of the mechanical properties of intrafusal bag1 fibers, which render it likely that in passive intrafusal bag1 fibers stretch activation will evoke the same mechanical behavior as dynamic gamma activation.
在对猫的胫骨前肌施加恒定幅度（7毫米）的斜坡-保持拉伸且拉伸速率在1至50毫米/秒之间变化的情况下，记录了初级肌梭传入纤维的放电模式。对于7条Ia纤维，在每秒10至120次刺激的各种动态γ刺激频率下记录放电模式。对于26条被称为袋1 Ia纤维类型的被动梭内纤维，在肌肉预拉伸逐渐增加的情况下获得放电模式。从每个放电模式中读取以下放电频率：初始活动（斜坡拉伸开始前的放电频率）、峰值动态放电（拉伸动态阶段结束时的放电频率）、最大静态值（MSt；拉伸静态阶段开始时的放电频率）和最终静态值（平台期第3秒结束时的放电频率）。将这四个放电频率值相对于MSt进行绘制，分别绘制动态γ刺激下Ia纤维和袋1 Ia纤维的图表。结果发现，两组Ia纤维的四个放电频率值与MSt之间的关系相同或非常相似。这意味着两组Ia纤维在响应斜坡-保持拉伸时产生（或多或少）相同的放电模式。此外，当两组Ia纤维具有相同的MSt时，确定它们的动态和静态反应。在这些情况下，动态γ激活梭的Ia纤维和被动梭的袋1 Ia纤维在拉伸特性方面没有发现差异。在讨论中，根据梭内袋1纤维的力学特性解释了两组Ia纤维行为的高度相似性，这使得被动梭内袋1纤维的拉伸激活可能引发与动态γ激活相同的力学行为。
