Dept. of Systems Neurophysiology, Graduate School of Medicine, Tokyo Medical and Dental Univ., 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan 113-8519.
J Neurophysiol. 2011 Nov;106(5):2675-87. doi: 10.1152/jn.00182.2011. Epub 2011 Aug 17.
This study was performed to characterize the properties of the suppression of smooth pursuit eye movement induced by electrical stimulation of the frontal eye field (FEF) in trained monkeys. At the stimulation sites tested, we first determined the threshold for generating electrically evoked saccades (Esacs). We then examined the suppressive effects of stimulation on smooth pursuit at intensities that were below the threshold for eliciting Esacs. We observed that FEF stimulation induced a clear deceleration of pursuit at pursuit initiation and also during the maintenance of pursuit at subthreshold intensities. The suppression of pursuit occurred even in the absence of catch-up saccades during pursuit, indicating that suppression influenced pursuit per se. We mapped the FEF area that was associated with the suppressive effect of stimulation on pursuit. In a wide area in the FEF, suppressive effects were observed for ipsiversive, but not contraversive, pursuit. In contrast, we observed the bilateral suppression of both ipsiversive and contraversive pursuit in a localized area in the FEF. This area coincided with the area in which we have previously shown that stimulation suppressed the generation of saccades in bilateral directions and also where fixation neurons that discharged during fixation were concentrated. On the basis of these results, we compared the FEF suppression of pursuit with that of saccades with regard to several physiological properties and then discussed the role of the FEF in the suppression of both pursuit and saccades, and particularly in the maintenance of visual fixation.
本研究旨在描述经额眼区（FEF）电刺激抑制平滑追踪眼动的特性，该研究在训练有素的猴子中进行。在测试的刺激部位，我们首先确定了产生电诱发扫视（Esacs）的阈值。然后，我们在低于诱发 Esacs 的阈值的强度下，检查了刺激对平滑追踪的抑制作用。我们观察到，FEF 刺激在追踪开始时以及在亚阈值强度下维持追踪时，明显地降低了追踪速度。即使在追踪过程中没有进行追迹性扫视，这种抑制作用也会发生，这表明抑制作用本身会影响追踪。我们绘制了与刺激对追踪的抑制作用相关的 FEF 区域图。在 FEF 的一个广泛区域中，抑制作用发生在同侧追踪，但不会发生对侧追踪。相比之下，在 FEF 的一个局部区域中，我们观察到同侧和对侧追踪都受到抑制。这个区域与我们之前已经证明的刺激抑制双侧扫视的区域相吻合，同时也是在固定期间放电的固定神经元集中的区域。基于这些结果，我们比较了 FEF 对追踪和扫视的抑制作用，从几个生理特性方面进行了比较，然后讨论了 FEF 在抑制追踪和扫视方面的作用，特别是在维持视觉固定方面的作用。
