Vercher J L, Gauthier G M
Université de Provence, Département de Psychophysiologie, Marseille, France.
Exp Brain Res. 1988;73(1):155-66. doi: 10.1007/BF00279669.
When the hand of the observer is used as a visual target, oculomotor performance evaluated in terms of tracking accuracy, delay and maximal ocular velocity is higher than when the subject tracks a visual target presented on a screen. The coordination control exerted by the motor system of the arm on the oculomotor system has two sources: the transfer of kinaesthetic information originating in the arm which increases the mutual coupling between the arm and the eyes and information from the arm movement efferent copy which synchronizes the motor activities of both subsystems (Gauthier et al. 1988; Gauthier and Mussa-Ivaldi 1988). We investigated the involvement of the cerebellum in coordination control during a visuo-oculo-manual tracking task. Experiments were conducted on baboons trained to track visual targets with the eyes and/or the hand. The role of the cerebellum was determined by comparing tracking performance defined in terms of delay, accuracy (position or velocity tracking errors) and maximal velocity, before and after lesioning the cerebellar dentate nucleus. Results showed that in the intact animal, ocular tracking was more saccadic when the monkey followed an external target than when it moved the target with its hand. After lesioning, eye-alone tracking of a visual target as well as eye-and-hand-tracking with the hand contralateral to the lesion was little if at all affected. Conversely, ocular tracking of the hand ipsilateral to the lesion side became more saccadic and the correlation between eye and hand movement decreased considerably while the delay between target and eyes increased. In normal animals, the delay between the eyes and the hand was close to zero, and maximal smooth pursuit velocity was around 100 degrees per second with close to unity gain; in eye-alone tracking the delay and maximal smooth pursuit velocity were 200 ms and 50 deg per second, respectively. After lesioning, delay and maximum velocity were respectively around 210 ms and 40 deg per second, that is close to the values measured in eye-alone tracking. Thus, after dentate lesioning, the oculomotor system was unable to use information from the motor system of the arm to enhance its performance. We conclude that the cerebellum is involved in the "coordination control" between the oculomotor and manual motor systems in visuo-oculo-manual tracking tasks.
当观察者的手作为视觉目标时，根据跟踪准确性、延迟和最大眼球速度评估的动眼神经性能要高于受试者跟踪屏幕上呈现的视觉目标时的情况。手臂运动系统对动眼神经系统施加的协调控制有两个来源：源自手臂的动觉信息的传递，这增加了手臂和眼睛之间的相互耦合；以及来自手臂运动传出副本的信息，它使两个子系统的运动活动同步（高蒂尔等人，1988年；高蒂尔和穆萨-伊瓦尔迪，1988年）。我们研究了小脑在视觉-动眼-手动跟踪任务中的协调控制作用。实验是在经过训练能用眼睛和/或手跟踪视觉目标的狒狒身上进行的。通过比较小脑齿状核损伤前后以延迟、准确性（位置或速度跟踪误差）和最大速度定义的跟踪性能，来确定小脑的作用。结果表明，在完整动物中，猴子跟踪外部目标时的眼球跟踪比用手移动目标时更多地表现为扫视。损伤后，单独用眼睛跟踪视觉目标以及用与损伤对侧的手进行眼手跟踪几乎没有受到影响。相反，损伤侧同侧手的眼球跟踪变得更多地表现为扫视，眼睛和手运动之间的相关性显著降低，而目标与眼睛之间的延迟增加。在正常动物中，眼睛和手之间的延迟接近零，最大平稳跟踪速度约为每秒100度，增益接近1；在单独眼睛跟踪中，延迟和最大平稳跟踪速度分别为200毫秒和每秒50度。损伤后，延迟和最大速度分别约为210毫秒和每秒40度，这接近单独眼睛跟踪中测得的值。因此，齿状核损伤后，动眼神经系统无法利用来自手臂运动系统的信息来提高其性能。我们得出结论，小脑参与了视觉-动眼-手动跟踪任务中动眼神经和手动运动系统之间的“协调控制”。
