Department of Systems Neurophysiology, Graduate School of Medicine, Tokyo Medical and Dental University, Yushima, Tokyo, Japan.
J Neurophysiol. 2009 Oct;102(4):2410-22. doi: 10.1152/jn.00234.2009. Epub 2009 Aug 12.
Electrical stimulation of the frontal eye field (FEF) has recently been reported to suppress the generation of saccades, which supports the idea that the FEF plays a role in maintaining attentive fixation. This study analyzed the activity of fixation neurons that discharged during fixation in the FEF in relation to visual fixation and saccades in trained monkeys. The neural activity of fixation neurons increased at the start of fixation and was maintained during fixation. When a fixation spot of light disappeared during steady fixation, different fixation neurons exhibited different categories of response, ranging from a decrease in activity to an increase in activity, indicating that there is a continuum of fixation neurons, from neurons with foveal visual-related activity to neurons with activity that is related to the motor act of fixating. Fixation neurons usually showed a decrease in their firing rate before the onset of visually guided saccades (Vsacs) and memory-guided saccades in any direction. The reduction in activity of fixation neurons nearly coincided with, or occurred slightly before, the increase in the activity of saccade-related movement neurons in the FEF in the same monkey. Although fixation neurons were scattered in the FEF, about two thirds of fixation neurons were concentrated in a localized area in the FEF at which electrical stimulation induced strong suppression of the initiation of Vsacs bilaterally. These results suggest that fixation neurons in the FEF are part of a suppression mechanism that could control the maintenance of fixation and the initiation of saccades.
目前已有研究报道，刺激额眼区（FEF）可抑制眼球运动的产生，这支持了 FEF 在维持注意力注视中的作用的观点。本研究分析了训练有素的猴子在 FEF 中固定时放电的固定神经元的活动与视觉固定和眼球运动的关系。固定神经元的神经活动在固定开始时增加，并在固定期间保持。当稳定固定期间固定光点消失时，不同的固定神经元表现出不同类别的反应，从活动减少到活动增加，这表明存在从具有中央凹视觉相关活动的神经元到与固定运动行为相关的活动的固定神经元的连续体。固定神经元通常在视觉引导的眼球运动（Vsacs）和任何方向的记忆引导的眼球运动之前显示出其放电率的降低。在同一只猴子的 FEF 中，与 Vsacs 相关的运动神经元的活动增加之前，固定神经元的活动减少几乎同时发生，或者略微提前发生。尽管固定神经元在 FEF 中分布广泛，但约三分之二的固定神经元集中在 FEF 的一个局部区域，在该区域，电刺激可双侧强烈抑制 Vsacs 的起始。这些结果表明，FEF 中的固定神经元是一种抑制机制的一部分，该机制可以控制固定的维持和眼球运动的起始。
