CORTICAL CONTROL OF DOUBLE-STEP SACCADES - IMPLICATIONS FOR SPATIAL ORIENTATION
CORTICAL CONTROL OF DOUBLE-STEP SACCADES - IMPLICATIONS FOR SPATIAL ORIENTATION
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DOI：
10.1002/ana.410380508
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发表时间：
1995-11-01
影响因子：
11.2
通讯作者：
KOMPF, D
中科院分区：
文献类型：
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作者：
HEIDE, W;BLANKENBURG, M;KOMPF, D
为了准确地定位空间中的视觉目标，尽管眼睛运动引起其视网膜图像的移位，大脑必须考虑其视网膜位置和关于当前眼睛位置或至少先前眼睛位移的信息。我们研究了这种能力与扫视眼球运动通过应用“双步”刺激，其中两个连续闪烁的目标灯的位置必须固定在两个连续的扫视后，他们的消失。由于第二次眼跳不会从看到第二个目标的空间位置开始，因此其视网膜坐标与所需第二次眼跳的运动坐标之间会出现不协调。然而，这些扫视是由32名健康的成年人相当准确地进行的。为了研究大脑皮层的贡献，我们记录了35例单侧半球局灶性病变患者的水平双步扫视。而额叶病变损害的时间属性，后顶叶病变引起空间辨距障碍或失败，甚至同向性第二眼扫视后，逆向第一眼扫视。这反映了无法补偿视网膜空间失调，通过使用非视网膜信息（必然放电）与以前的扫视到对侧半野的眼睛位移。总之，顶叶皮层是至关重要的空间恒定性扫视。
To accurately localize a visual target in space despite eye movement-induced shifts of its retinal image, the brain must take into account both its retinal location and information about current eye position or at least the preceding eye displacement. We examined this ability with respect to saccadic eye movements by applying ''double-step'' stimuli, where the locations of two sequentially flashed target lights have to be fixated by two successive saccades performed after their disappearance. As the 2nd saccade will not start at the spatial location from which the 2nd target was seen, a dissonance arises between its retinal coordinates and the motor coordinates of the required 2nd saccade. Nevertheless, these saccades were performed quite accurately by 32 healthy human adults. To investigate the contribution of the cerebral cortex, we recorded horizontal double-step saccades in 35 patients with focal unilateral hemispheric lesions. Whereas frontal lesions impaired temporal properties, posterior parietal lesions caused spatial dysmetria or failure of even ipsiversive 2nd saccades following contraversive 1st saccades. This reflects an inability to compensate for retino-spatial dissonance by using nonretinal information (corollary discharge) about eye displacement associated with a previous saccade into the contralesional hemifield. In conclusion, the parietal cortex is crucial for spatial constancy across saccades.