Heide W, Binkofski F, Seitz R J, Posse S, Nitschke M F, Freund H J, Kömpf D
Department of Neurology, Medical University at Lübeck, D-23538 Lübeck, Germany.
Eur J Neurosci. 2001 Mar;13(6):1177-89. doi: 10.1046/j.0953-816x.2001.01472.x.
To determine the cortical areas controlling memory-guided sequences of saccadic eye movements, we performed functional magnetic resonance imaging (fMRI) in six healthy adults. Subjects had to perform a memorized sequence of three saccades in darkness, after a triple-step stimulus of successively flashed laser targets. To assess the differential contribution of saccadic subfunctions, we applied several control conditions, such as central fixation with or without triple-step visual stimulation, self-paced saccades in darkness, visually guided saccades and single memory-guided saccades. Triple-step saccades strongly activated the regions of the frontal eye fields, the adjacent ventral premotor cortex, the supplementary eye fields, the anterior cingulate cortex and several posterior parietal foci in the superior parietal lobule, the precuneus, and the middle and posterior portion of the intraparietal sulcus, the probable location of the human parietal eye field. Comparison with the control conditions showed that the right intraparietal sulcus and parts of the frontal and supplementary eye fields are more involved in the execution of triple-step saccades than in the other saccade tasks. In accordance with evidence from clinical lesion studies, we propose that the supplementary eye field essentially controls the triggering of memorized saccadic sequences, whereas activation near the middle portion of the right intraparietal sulcus appears to reflect the necessary spatial computations, including the use of extraretinal information (efference copy) about a saccadic eye displacement for updating the spatial representation of the second or third target of the triple-step sequence.
为了确定控制记忆引导的扫视眼动序列的皮质区域，我们对6名健康成年人进行了功能磁共振成像（fMRI）。在连续闪烁激光靶点的三步刺激后，受试者必须在黑暗中执行一个由三个扫视组成的记忆序列。为了评估扫视子功能的不同贡献，我们应用了几种对照条件，例如有或没有三步视觉刺激的中央注视、黑暗中自主节奏的扫视、视觉引导的扫视和单个记忆引导的扫视。三步扫视强烈激活了额叶眼区、相邻的腹侧运动前皮质、辅助眼区、前扣带回皮质以及顶上小叶、楔前叶和顶内沟中、后部的几个后顶叶焦点区域，这些区域可能是人顶叶眼区的位置。与对照条件的比较表明，右侧顶内沟以及额叶和辅助眼区的部分区域在执行三步扫视时比在其他扫视任务中参与度更高。根据临床病变研究的证据，我们提出辅助眼区主要控制记忆扫视序列的触发，而右侧顶内沟中部附近的激活似乎反映了必要的空间计算，包括利用关于扫视眼位移的视网膜外信息（传出副本）来更新三步序列中第二个或第三个目标的空间表征。
