Fujii N, Mushiake H, Tanji J
Department of Physiology, Tohoku University School of Medicine, Sendai 980, Japan.
J Neurophysiol. 1998 Apr;79(4):2240-4. doi: 10.1152/jn.1998.79.4.2240.
We trained two monkeys to perform a fixation task. Intracortical microstimulation (ICMS) was applied to the monkey frontal eye field (FEF) while monkeys were fixating on one of five fixation LEDs. The ICMS was applied in two different manners. Under the single stimulation condition, ICMS was delivered to either right or left FEF. Under the paired stimulation condition, bilateral FEF were successively stimulated with an interval of 30-250 ms. The single stimulation elicited contraversive saccades. As reported previously, these saccades were not much affected by initial eye positions, maintaining the same vector. In contrast, the paired stimulation elicited double-step saccades. The first of the paired stimulation elicited constant vector saccades, but the second of the paired stimulation evoked saccades whose vector varied greatly depending on the eye position at the start of individual saccades. The second saccades, starting from various initial positions, were directed to the endpoint of saccades that were elicited from the same FEF site under the single stimulation condition. Endpoints of second saccades varied little despite variations of intervals of the stimulation pairs, ranging from 60 to 150 ms. On the basis of these observations, we propose a novel view that the FEF is involved in directing saccades to an internally referenced visual target.
我们训练了两只猴子执行注视任务。当猴子注视五个注视发光二极管中的一个时，对猴子的额叶眼区（FEF）进行皮层内微刺激（ICMS）。ICMS以两种不同方式施加。在单次刺激条件下，ICMS被施加到右侧或左侧FEF。在配对刺激条件下，双侧FEF以30 - 250毫秒的间隔相继受到刺激。单次刺激引发对侧性扫视。如先前报道，这些扫视受初始眼位影响不大，保持相同向量。相比之下，配对刺激引发双步扫视。配对刺激中的第一次引发恒定向量扫视，但配对刺激中的第二次引发的扫视其向量根据各个扫视开始时的眼位有很大变化。从不同初始位置开始的第二次扫视指向在单次刺激条件下从相同FEF位点引发的扫视的终点。尽管刺激对的间隔在60到150毫秒之间变化，但第二次扫视的终点变化很小。基于这些观察结果，我们提出一种新观点，即FEF参与将扫视导向内部参考视觉目标。
