Keating E G, Gooley S G
Department of Anatomy and Cell Biology, SUNY-Health Science Center, Syracuse 13210.
Exp Brain Res. 1988;70(2):385-98. doi: 10.1007/BF00248363.
The experiment explored the networks through which signals arising from visual areas of cortex control saccadic eye movements. Electrical stimulation of the inferior parietal and the occipital cortex (here termed the "posterior eye fields") normally evokes saccadic eye movements. We replicated previous reports that these evoked eye movements ceased after large tectal ablations. This initial finding suggested that the "posterior eye fields" depended on a single route of access to the saccade generator, one descending through the superior colliculus (SC). On closer examination, the critical lesion appeared to be one which removed the SC and cut efferents from the frontal eye field (FEF) coursing nearby. Subsequently we confirmed that eye movements evoked from the posterior eye fields ceased after cooling the SC, or cutting its efferents- but only when one of these procedures was combined with FEF ablation. Thus, visual signals from the occipital and inferior parietal cortex have more than one, but perhaps only two routes of access to the oculomotor system. One passes through the superior colliculus, the other through the frontal eye field. Ancillary experiments revealed that inferior parietal and FEF ablations, alone or combined, do not disrupt saccades evoked from the occipital lobe. Striate and prestriate areas can therefore use their own direct input to the SC or to the basal ganglia to drive saccadic eye movements.
该实验探究了皮质视觉区域产生的信号控制眼球跳动的神经网络。对顶下叶和枕叶皮质（此处称为“后眼区”）进行电刺激通常会诱发眼球跳动。我们重复了之前的报告，即这些诱发的眼球运动在进行大面积顶盖切除术后会停止。这一初步发现表明，“后眼区”依赖于一条通向眼球运动发生器的单一通路，即一条通过上丘（SC）下行的通路。进一步检查发现，关键损伤似乎是切除了上丘并切断了附近额叶眼区（FEF）的传出纤维。随后我们证实，冷却上丘或切断其传出纤维后，后眼区诱发的眼球运动停止了——但只有当这些操作之一与额叶眼区切除相结合时才会如此。因此，来自枕叶和顶下叶皮质的视觉信号有不止一条，也许只有两条通向动眼系统的通路。一条通过上丘，另一条通过额叶眼区。辅助实验表明，单独或联合切除顶下叶和额叶眼区不会干扰从枕叶诱发的眼球跳动。因此，纹状区和纹前区可以利用它们自己对上丘或基底神经节的直接输入来驱动眼球跳动。
