Miles F A
Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Eur J Neurosci. 1998 Mar;10(3):811-22. doi: 10.1046/j.1460-9568.1998.00112.x.
Primates have several reflexes that generate eye movements to compensate for bodily movements that would otherwise disturb their gaze and undermine their ability to process visual information. Two vestibulo-ocular reflexes compensate selectively for rotational and translational disturbances of the head, and each has visual backups that operate as negative feedback tracking mechanisms to deal with any residual disturbances of gaze. Of particular interest here are three recently discovered visual tracking mechanisms that specifically address translational disturbances and operate in machine-like fashion with ultra-short latencies (< 60 ms in monkeys, < 85 ms in humans). These visual reflexes deal with motions in all three dimensions and operate as automatic servos, using preattentive parallel processing to provide signals that initiate eye movements before the observer is even aware that there has been a disturbance. This processing is accomplished by visual filters each tuned to a different feature of the binocular images located in the immediate vicinity of the plane of fixation. Two of the reflexes use binocular stereo cues and the third is tuned to particular patterns of optic flow associated with the observer's forward motion. Some stereoanomalous subjects show tracking deficits that can be attributed to a lack of just one subtype of cortical cell encoding motion in one particular direction in a narrow depth plane centred on fixation. Despite their rapid, reflex nature, all three mechanisms rely on cortical processing and evidence from monkeys supports the hypothesis that all are mediated by the medial superior temporal (MST) area of cortex. Remarkably, MST seems to represent the first stage in cortical motion processing at which the visual error signals driving each of the three reflexes are fully elaborated at the level of individual cells.
灵长类动物有几种反射，可产生眼球运动以补偿身体运动，否则这些运动会干扰它们的视线并削弱其处理视觉信息的能力。两种前庭眼反射分别选择性地补偿头部的旋转和平移干扰，并且每种反射都有视觉备份，作为负反馈跟踪机制来处理任何残留的视线干扰。这里特别有趣的是最近发现的三种视觉跟踪机制，它们专门处理平移干扰，并以类似机器的方式运行，具有极短的延迟（猴子中<60毫秒，人类中<85毫秒）。这些视觉反射处理所有三个维度的运动，并作为自动伺服系统运行，使用前注意并行处理来提供信号，在观察者甚至还未意识到有干扰之前就启动眼球运动。这种处理是通过视觉滤波器完成的，每个滤波器都调谐到位于注视平面紧邻区域的双目图像的不同特征。其中两种反射使用双目立体线索，第三种则调谐到与观察者向前运动相关的特定光流模式。一些立体视觉异常的受试者表现出跟踪缺陷，这可归因于在以注视为中心的狭窄深度平面中，仅缺少一种编码特定方向运动的皮质细胞亚型。尽管它们具有快速的反射性质，但所有这三种机制都依赖于皮质处理，来自猴子的证据支持这样的假设，即所有这些机制都是由皮质的内侧颞上区（MST）介导的。值得注意的是，MST似乎代表了皮质运动处理的第一阶段，在这个阶段，驱动这三种反射的视觉误差信号在单个细胞水平上得到充分阐述。
