Department of Neurology, University Hospital, LMU Munich, Germany.
German Center for Vertigo and Balance Disorders, University Hospital, LMU Munich, Germany.
J Neurophysiol. 2020 Feb 1;123(2):571-586. doi: 10.1152/jn.00468.2019. Epub 2019 Dec 25.
The right frontal eye field (rFEF) is associated with visual perception and eye movements. rFEF is activated during optokinetic nystagmus (OKN), a reflex that moves the eye in response to visual motion (optokinetic stimulation, OKS). It remains unclear whether rFEF plays causal perceptual and/or oculomotor roles during OKS and OKN. To test this, participants viewed a leftward-moving visual scene of vertical bars and judged whether a flashed dot was moving. Single pulses of transcranial magnetic stimulation (TMS) were applied to rFEF on half of trials. In half of blocks, to explore oculomotor control, participants performed an OKN in response to the OKS. rFEF TMS, during OKN, made participants more accurate on trials when the dot was still, and it slowed eye movements. In separate blocks, participants fixated during OKS. This not only controlled for eye movements but also allowed the use of EEG to explore the FEF's role in visual motion discrimination. In these blocks, by contrast, leftward dot motion discrimination was impaired, associated with a disruption of the frontal-posterior balance in alpha-band oscillations. None of these effects occurred in a control site (M1) experiment. These results demonstrate multiple related yet dissociable causal roles of the right FEF during optokinetic stimulation. This study demonstrates causal roles of the right frontal eye field (FEF) in motion discrimination and eye movement control during visual scene motion: previous work had only examined other stimuli and eye movements such as saccades. Using combined transcranial magnetic stimulation and EEG and a novel optokinetic stimulation motion-discrimination task, we find evidence for multiple related yet dissociable causal roles within the FEF: perceptual processing during optokinetic stimulation, generation of the optokinetic nystagmus, and the maintenance of alpha oscillations.
右侧额眼区（rFEF）与视觉感知和眼球运动有关。rFEF 在视动性眼球震颤（OKN）期间被激活，这是一种响应视觉运动（视动刺激，OKS）而使眼球运动的反射。目前尚不清楚 rFEF 在 OKS 和 OKN 期间是否发挥因果知觉和/或眼球运动作用。为了测试这一点，参与者观看了一个向左移动的垂直条视觉场景，并判断闪烁的点是否在移动。在一半的试验中，经颅磁刺激（TMS）的单脉冲施加于 rFEF。在一半的块中，为了探索眼球运动控制，参与者对 OKS 做出 OKN 反应。rFEF TMS 在 OKN 期间使参与者在点静止时更准确，并且使眼球运动减慢。在单独的块中，参与者在 OKS 期间注视。这不仅控制了眼球运动，而且还允许使用 EEG 来探索 FEF 在视觉运动辨别中的作用。相比之下，在这些块中，左向点运动辨别受损，与 alpha 波段振荡中的额后平衡破坏有关。在对照部位（M1）实验中未发生这些影响。这些结果表明，在视动刺激期间，右侧 FEF 具有多个相关但可分离的因果作用。本研究表明，右侧额眼区（FEF）在视觉场景运动中的运动辨别和眼球运动控制中具有因果作用：以前的工作仅检查了其他刺激和眼球运动，例如扫视。使用经颅磁刺激和 EEG 的组合以及新颖的视动刺激运动辨别任务，我们发现 FEF 内存在多个相关但可分离的因果作用的证据：视动刺激期间的知觉处理，视动性眼球震颤的产生，以及 alpha 振荡的维持。
