Cerebral Mechanism of Visually Guided Eye Movements

我们试图揭示前额眼场（FEF）在视觉引导下猕猴眼球运动产生中的作用。我们首先将FEF的范围定位为皮层区域，在该区域中，皮层内微刺激引发了跳眼运动。发现该区域局限于弓状沟的前侧壁，向前延伸到皮质暴露表面。在这样定义的FEF中，关于电诱发的眼跳的振幅存在地形组织。我们在皮质位点的所有深度都获得了相似的幅度和方向的扫视。当刺激不同的位点时，眼动向量的性质发生了系统的变化。在FEF的外侧部分有一个小的扫视，在内侧部分有一个大的扫视。我们还通过记录视觉神经元来研究FEF的视觉输入。它们在FEF中广泛存在，并且它们再次被地形组织起来。在外侧部分，神经元在凝视中心附近有小的接受野。内侧部分的神经元在周围视野中具有较大的感受野。然后，我们进一步研究了视觉输入和每个位点的运动输出之间的关系。扫视将视线带入刺激前视觉感受野所占据的区域，说明视觉输入促进了扫视的产生。考虑到这些结果以及传入和传出神经结构的差异，我们假设FEF在视觉物体触发的扫视产生中起重要作用。

We tried to reveal the role of the frontal eye field (FEF) in the generation of visually guided eye movements using alert macaque monkeys. We first localized the extent of the FEF as the cortical area in which intracortical microstimulation elicites saccadic eye movements. The area was found to be restricted in the anterior bank of the arcuate sulcus extending anteriorly to the cortical exposed surface. In thus defined FEF, there was topographic organization regarding the amplitude of the electrically elicited saccade. We obtained saccades with similar amplitude and direction in all depth of a cortical locus. When stimulating different loci, saccade vector properties changed systematically. A small saccade was elicited in the lateral portion of FEF, and a large one was in the medial portion. We also investigated the visual input to the FEF by recording visual neurons. They were diffusely present in the FEF, and they were again topographically organized. In the lateral portion, neurons had small receptive fields near the center of gaze. Neurons in the medial portion had large receptive fields in the peripheral visual field. Then, we further examined the relation between the visual input and the motor (saccadic) output in each locus. The saccade brought the visual line into a part where the visual receptive field had occupied before the stimulation, suggesting that the visual input facilitates the saccade generation. Considering these results together with differentiation in the afferent and efferent neural structures, we postulated that the FEF plays an important role in the generation of saccades triggered by a visual object.