No oculomotor plant, no final common path.
No oculomotor plant, no final common path.
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没有动眼植物，没有最终的共同路径。
DOI：
10.1076/stra.11.4.205.24308
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发表时间：
2003
期刊：
影响因子：
0.9
通讯作者：
Miller,Joel
中科院分区：
文献类型：
--
作者：
Miller,Joel
脑干记录研究推翻了存在动眼植物（运动神经元放电率和眼睛位置之间存在固定关系）的假设，该研究表明这种关系取决于哪个超核子系统决定放电率。但仍有可能存在最终的共同路径（FCP），即放电频率和肌肉力量之间的固定关系。但是，脑干记录研究预测，对于给定的眼睛位置，会聚凝视时的外直肌 (LR) 力（也可能还有内直肌 (MR) 力）会高于非会聚凝视时的力。我们最近测量了这些力，发现它们的收敛性稍低，从而反驳了 FCP 假设。因此，甚至运动神经元放电率和肌肉力量之间的关系也在超核控制之下。哪些外周动眼神经关节可以改变放电速率与肌肉力量的关系？：（1）可主动移动的 EOM 滑轮可以通过改变肌肉长度来改变给定动眼神经支配的动眼肌肉力量。 (2)“外部”运动神经元可以与栅栏末端和非抽搐整体 EOM 纤维一起充当伽马传出神经。 (3) 并行和串联连接的肌纤维之间可能会出现复杂的非线性相互作用。
The assumption that there is an oculomotor plant, a fixed relationship between motoneuron firing rate and eye position, is disproved by brainstem recording studies showing that this relationship depends on which supernuclear subsystem determines firing rate. But it remains possible that there is a final common path (FCP), a fixed relationship between firing rate and muscle force. But then, brainstem recording studies predict that lateral rectus (LR) forces (and probably medial rectus (MR) forces, as well) will be higher in converged than in unconverged gaze for a given eye position. We recently measured these forces and found that they are slightly lower in convergence, disproving the FCP hypothesis. Thus, even the relationship between motoneuron firing rate and muscle force is under supernuclear control. What peripheral oculomotor articulations could vary the relationship of firing rate to muscle force?: (1) Actively movable EOM pulleys could alter oculorotary muscle force for a given oculorotory innervation by altering muscle lengths. (2) ‘Outer’ motoneurons may function as gamma efferents in conjunction with palisade endings and non-twitch global EOM fibers. (3) Complex nonlinear interactions likely arise among both parallel and serially connected muscle fibers.