Sailer Uta, Eggert Thomas, Straube Andreas
Section for Physiology, Department of Integrative Medical Biology, Umeå University, SE-90187 Umeå, Sweden.
Behav Brain Res. 2005 May 7;160(1):72-87. doi: 10.1016/j.bbr.2004.11.020. Epub 2004 Dec 21.
This study investigated the effect of cerebellar lesions on temporal prediction and coordination in eye and hand movements. Nine patients with cerebellar lesions were compared to controls while they made saccades with and without simultaneous pointing movements towards a target that was either temporally predictable or non-predictable. The direction and amplitude of the target step was always predictable. Patients made much more early and late saccades than controls, but an equal amount of visually triggered saccades. This suggests that inappropriate saccades could be suppressed during the preparation of a goal-directed saccade. Hand movement frequency did not differ between both groups. Thus, cerebellar lesions can induce inappropriate saccades more easily than inappropriate hand movements. Controls, but not patients, generated visually triggered saccades of shorter latencies when the target was temporally predictable. Thus, the patients could not use information about target timing to synchronise visually triggered saccades with the target. They could, however, use this information to improve the suppression of inappropriate saccades. Regarding coordination, patients showed impairments in synchronising saccades with hand movements. Nevertheless, hand movements led to an enhancement of anticipatory saccades in patients as in controls. Moreover, hand movements and temporal predictability affected saccadic accuracy in both groups similarly. These results suggest that cerebellar lesions do not generally prevent access to temporal information on the rhythm of a target sequence or the timing of a planned hand movement. More specifically, the cerebellum seems to be crucial for synchronizing saccades with such learned or planned temporal events.
本研究调查了小脑损伤对眼动和手动的时间预测及协调能力的影响。研究人员将9名小脑损伤患者与对照组进行比较，让他们在进行眼球快速运动（扫视）时，同时对一个时间上可预测或不可预测的目标进行指向运动，或者只进行扫视。目标步骤的方向和幅度始终是可预测的。与对照组相比，患者出现的早发和迟发扫视更多，但视觉触发的扫视数量相同。这表明在准备目标导向的扫视过程中，不适当的扫视可以被抑制。两组之间的手部运动频率没有差异。因此，小脑损伤比不适当的手部运动更容易诱发不适当的扫视。当目标在时间上可预测时，对照组（而非患者组）产生的视觉触发扫视潜伏期更短。因此，患者无法利用目标时间信息来使视觉触发的扫视与目标同步。然而，他们可以利用这些信息来更好地抑制不适当的扫视。在协调方面，患者在使扫视与手部运动同步方面存在障碍。尽管如此，与对照组一样，手部运动在患者中也会增强预期性扫视。此外，手部运动和时间可预测性对两组扫视准确性的影响相似。这些结果表明，小脑损伤一般不会妨碍获取关于目标序列节奏或计划手部运动时间的时间信息。更具体地说，小脑似乎对于使扫视与这种学习到的或计划好的时间事件同步至关重要。
