Bourrelly Clara, Quinet Julie, Goffart Laurent
Institut de Neurosciences de la Timone, UMR 7289 Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France.
Laboratoire Psychologie de la Perception, UMR 8242 Centre National de la Recherche Scientifique, Université Paris Descartes, Paris, France.
J Neurophysiol. 2018 Oct 1;120(4):1640-1654. doi: 10.1152/jn.00278.2018. Epub 2018 Jul 11.
The caudal fastigial nuclei (cFN) are the output nuclei by which the medio-posterior cerebellum influences the production of saccadic and pursuit eye movements. We investigated the consequences of unilateral inactivation on the pursuit eye movement made immediately after an interceptive saccade toward a centrifugal target. We describe here the effects when the target moved along the horizontal meridian with a 10 or 20°/s speed. After muscimol injection, the monkeys were unable to track the present location of the moving target. During contralesional tracking, the velocity of postsaccadic pursuit was reduced. This slowing was associated with a hypometria of interceptive saccades such that gaze direction always lagged behind the moving target. No correlation was found between the sizes of saccade undershoot and the decreases in pursuit speed. During ipsilesional tracking, the effects on postsaccadic pursuit were variable across the injection sessions, whereas the interceptive saccades were consistently hypermetric. Here also, the ipsilesional pursuit disorder was not correlated with the saccade hypermetria either. The lack of correlation between the sizes of saccade dysmetria and changes of postsaccadic pursuit speed suggests that cFN activity exerts independent influences on the neural processes generating the saccadic and slow eye movements. It also suggests that the cFN is one locus where the synergy between the two motor categories develops in the context of tracking a moving visual target. We explain how the different fastigial output channels can account for these oculomotor tracking disorders. NEW & NOTEWORTHY Inactivation of the caudal fastigial nucleus impairs the ability to track a moving target. The accuracy of interceptive saccades and the velocity of postsaccadic pursuit movements are both altered, but these changes are not correlated. This absence of correlation is not compatible with an impaired common command feeding the circuits producing saccadic and pursuit eye movements. However, it suggests an involvement of caudal fastigial nuclei in their synergy to accurately track a moving target.
尾侧顶核（cFN）是中后小脑影响扫视和追踪眼球运动产生的输出核团。我们研究了单侧失活对向离心目标进行拦截性扫视后立即进行的追踪眼球运动的影响。在此，我们描述了目标以10或20°/秒的速度沿水平子午线移动时的效果。注射蝇蕈醇后，猴子无法追踪移动目标的当前位置。在对侧追踪期间，扫视后追踪的速度降低。这种减慢与拦截性扫视的运动范围减小有关，使得注视方向总是落后于移动目标。未发现扫视欠冲的大小与追踪速度降低之间存在相关性。在同侧追踪期间，各注射时段对扫视后追踪的影响各不相同，而拦截性扫视始终是超运动范围的。同样，同侧追踪障碍也与扫视超运动范围无关。扫视测量误差的大小与扫视后追踪速度变化之间缺乏相关性，这表明cFN活动对产生扫视和缓慢眼球运动的神经过程施加独立影响。这也表明cFN是在追踪移动视觉目标的背景下两种运动类别之间协同作用发展的一个位点。我们解释了不同的顶核输出通道如何解释这些眼球运动追踪障碍。新发现与值得注意之处尾侧顶核失活会损害追踪移动目标的能力。拦截性扫视的准确性和扫视后追踪运动的速度均发生改变，但这些变化并无相关性。这种缺乏相关性与为产生扫视和追踪眼球运动的回路提供指令受损不相符。然而，这表明尾侧顶核参与了它们的协同作用以准确追踪移动目标。
