Washington University School of Medicine, Department of Anatomy and Neurobiology, Box 8108, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
J Neurophysiol. 2011 Feb;105(2):640-9. doi: 10.1152/jn.00737.2010. Epub 2010 Nov 24.
Retinal information is two-dimensional, whereas eye movements are three-dimensional. The oculomotor system solves this degrees-of-freedom problem by constraining eye positions to zero torsion (Listing's law) and determining how eye velocities change with eye position (half-angle rule). Here we test whether the oculomotor plant, in the absence of well-defined neural commands, can implement these constrains mechanically, not just in a primary position but for all eye and head orientations. We stimulated the abducens nerve at tertiary eye positions and when ocular counterroll was induced at tilted head orientations. Stimulation-induced eye velocities follow the half-angle rule, even for tertiary eye positions, and microstimulation at tilted head orientations elicits eye positions that adhere to torsionally shifted planes, similar to naturally occurring eye movements. These results support the notion that oculomotor plant can continuously apply these three-dimensional rules correctly and appropriately for all eye and head orientations that obey Listing's law, demonstrating a major role of peripheral biomechanics in motor control.
视网膜信息是二维的，而眼球运动是三维的。眼动系统通过将眼球位置约束为零扭转（ Listing 定律）并确定眼球速度随眼球位置的变化（半角法则）来解决自由度问题。在这里，我们测试了在没有明确的神经指令的情况下，眼动系统是否可以机械地实现这些约束，不仅在主要位置，而且在所有眼睛和头部的方位。我们在第三眼位置刺激展神经，并在倾斜头部位置诱导眼对抗滚动时进行刺激。刺激诱导的眼球速度遵循半角法则，即使在第三眼位置也是如此，在倾斜头部位置的微刺激会引起眼球位置，这些位置符合扭转移位的平面，类似于自然发生的眼球运动。这些结果支持了这样一种观点，即眼动系统可以连续地正确地应用这些三维规则，适用于所有遵循 Listing 定律的眼睛和头部方位，这表明外围生物力学在运动控制中起着重要作用。
