Bergeron André, Matsuo Satoshi, Guitton Daniel
Department of Neurology and Neurosurgery and Montreal Neurological Institute, McGill University, 3801 University St., Montreal, Quebec H3A2B4, Canada.
Nat Neurosci. 2003 Apr;6(4):404-13. doi: 10.1038/nn1027.
The superior colliculus (SC) is important for generating coordinated eye-head gaze saccades. Its deeper layers contain a retinotopically organized motor map in which each site is thought to encode a specific gaze saccade vector. Here we show that this fundamental assumption in current models of collicular function does not hold true during horizontal multi-step gaze shifts in darkness that are directed to a goal and composed of a sequence of gaze saccades separated by periods of steady fixation. At the start of a multi-step gaze shift in cats, neural activity on the SC's map was located caudally to encode the overall amplitude of the gaze displacement, not the first saccade in the sequence. As the gaze shift progressed, the locus of activity moved to encode the error between the goal and the current gaze position. Contrary to common belief, the locus of activity never encoded gaze saccade amplitude, except for the last saccade in the sequence.
上丘（SC）对于产生协调的眼-头凝视扫视很重要。其深层包含一个视网膜拓扑组织的运动图谱，其中每个位点被认为编码一个特定的凝视扫视向量。在这里，我们表明，在黑暗中指向目标且由一系列被稳定注视期隔开的凝视扫视组成的水平多步凝视转移过程中，当前丘功能模型中的这一基本假设并不成立。在猫的多步凝视转移开始时，上丘图谱上的神经活动位于尾侧，以编码凝视位移的总体幅度，而不是序列中的第一个扫视。随着凝视转移的进行，活动位点移动以编码目标与当前凝视位置之间的误差。与普遍看法相反，活动位点从未编码过凝视扫视幅度，序列中的最后一个扫视除外。
