Leigh R J, Huebner W P, Gordon J L
Department of Neurology, Veterans Affairs Medical Center, Cleveland, Ohio.
J Vestib Res. 1994 Sep-Oct;4(5):347-53.
In studies over the past 30 years, D. A. Robinson and colleagues established that the dynamic characteristics of smooth pursuit eye movements (SP) are different at the onset from those at the cessation of the response. They proposed that cessation of SP was due to a separate fixation system. During head movements, both fixation and SP may contribute to gaze stabilization. We investigated the relative contributions of fixation and SP to the "visually enhanced" vestibulo-ocular reflex (VVOR) using a paradigm requiring a transition from VVOR to combined eye-head tracking (CEHT). We found, in four normal subjects, that ringing typical of SP generally did not occur during VVOR, but that it often appeared after the transition to CEHT. The findings were different in two patients with absent peripheral vestibular function; ringing typical of SP occurred always during VVOR but disappeared during the onset of CEHT. These results can be explained by a model in which an internal representation of target velocity serves as input to parallel SP and fixation systems, and as the determinant of which of the two systems will provide the command signal. Interpretation of our data using this model indicates that either fixation or SP systems may "visually enhance" the VOR, depending on the magnitude of retinal error velocity that remains after vestibular eye movements have been generated.
在过去30年的研究中，D. A. 罗宾逊及其同事证实，平稳跟踪眼动（SP）的动态特征在反应开始时与结束时有所不同。他们提出，SP的停止是由于一个独立的注视系统。在头部运动期间，注视和SP都可能有助于注视稳定。我们使用一种需要从视前庭眼反射（VVOR）过渡到联合眼-头跟踪（CEHT）的范式，研究了注视和SP对“视觉增强”视前庭眼反射（VVOR）的相对贡献。我们发现，在四名正常受试者中，典型的SP震颤在VVOR期间通常不会出现，但在过渡到CEHT后经常出现。在两名外周前庭功能缺失的患者中，结果有所不同；典型的SP震颤在VVOR期间总是出现，但在CEHT开始时消失。这些结果可以用一个模型来解释，在该模型中，目标速度的内部表征作为并行的SP和注视系统的输入，并作为决定两个系统中哪个将提供命令信号的因素。使用该模型对我们的数据进行解释表明，取决于在前庭眼动产生后残留的视网膜误差速度的大小，注视或SP系统都可能“视觉增强”VOR。
