Klier Eliana M, Meng Hui, Angelaki Dora E
Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Neurosci. 2006 Mar 8;26(10):2732-7. doi: 10.1523/JNEUROSCI.3610-05.2006.
Motor systems often require that superfluous degrees of freedom be constrained. For the oculomotor system, a redundancy in the degrees of freedom occurs during visually guided eye movements and is solved by implementing Listing's law and the half-angle rule, kinematic constraints that limit the range of eye positions and angular velocities used by the eyes. These constraints have been attributed either to neurally generated commands or to the physical mechanics of the eye and its surrounding muscles and tissues (i.e., the ocular plant). To directly test whether the ocular plant implements the half-angle rule, critical to the maintenance of Listing's law, we microstimulated the abducens nerve with the eye at different initial vertical eye positions. We report that the electrically evoked eye velocity exhibits the same eye position dependence as seen in visually guided smooth-pursuit eye movements. These results support an important role for the ocular plant in providing a solution to the degrees-of-freedom problem during eye movements.
运动系统常常需要对多余的自由度加以限制。对于动眼系统而言，在视觉引导的眼球运动过程中会出现自由度冗余的情况，而这一问题通过实施利斯廷定律和半角规则得以解决，这两个运动学约束限制了眼睛所使用的眼位范围和角速度。这些约束要么归因于神经产生的指令，要么归因于眼睛及其周围肌肉和组织（即眼球运动装置）的物理力学特性。为了直接测试眼球运动装置是否实施了对半角规则（这对利斯廷定律的维持至关重要），我们在眼睛处于不同初始垂直眼位时对展神经进行了微刺激。我们报告称，电诱发的眼速度表现出与视觉引导的平稳跟踪眼球运动中所见相同的眼位依赖性。这些结果支持了眼球运动装置在为眼球运动过程中的自由度问题提供解决方案方面发挥重要作用。
