Hsu Tzu-Yu, Hsu Yu-Fan, Wang Hsin-Yi, Wang Chin-An
Graduate Institute of Mind, Brain, and Consciousness (GIMBC), Taipei Medical University, Taipei, Taiwan.
Brain and Consciousness Research Center (BCRC), TMU-Shuang Ho Hospital, New Taipei City, Taiwan.
Eur J Neurosci. 2021 Apr 26. doi: 10.1111/ejn.15253.
The appearance of a salient stimulus evokes a series of orienting responses including saccades and pupil size to prepare the body for appropriate action. The midbrain superior colliculus (SC) that receives critical control signals from the frontal eye field (FEF) is hypothesized to coordinate all components of orienting. It has shown recently that the FEF, together with the SC, is also importantly involved in the control of pupil size, in addition to its well-documented role in eye movements. Although the role of the FEF in pupil size is demonstrated in monkeys, its role in human pupil responses and the coordination between pupil size and saccades remains to be established. Through applying continuous theta-burst stimulation over the right FEF and vertex, we investigated the role of the FEF in human pupil and saccade responses evoked by a salient stimulus, and the coordination between pupil size and saccades. Our results showed that neither saccade reaction times (SRT) nor pupil responses evoked by salient stimuli were modulated by FEF stimulation. In contrast, the correlation between pupil size and SRTs in the contralateral stimulus condition was diminished with FEF stimulation, but intact with vertex stimulation. Moreover, FEF stimulation effects between saccade and pupil responses associated with salient stimuli correlated across participants. This is the first transcranial magnetic stimulation (TMS) study on the pupil orienting response, and our findings suggest that human FEF was involved in coordinating pupil size and saccades, but not involved in the control of pupil orienting responses.
显著刺激的出现会引发一系列定向反应，包括扫视和瞳孔大小变化，从而使身体为适当行动做好准备。从中脑上丘（SC）接收来自额叶眼区（FEF）关键控制信号的情况来看，推测它能协调定向的所有组成部分。最近研究表明，FEF除了在眼动中发挥的作用已得到充分证明外，它与SC一起在瞳孔大小控制方面也起着重要作用。尽管FEF在瞳孔大小方面的作用已在猴子身上得到证实，但其在人类瞳孔反应以及瞳孔大小与扫视之间的协调作用仍有待确定。通过在右侧FEF和头顶施加连续的theta波爆发刺激，我们研究了FEF在由显著刺激诱发的人类瞳孔和扫视反应中的作用，以及瞳孔大小与扫视之间的协调。我们的结果表明，无论是扫视反应时间（SRT）还是由显著刺激诱发的瞳孔反应都不受FEF刺激的调节。相反，在对侧刺激条件下，FEF刺激会减弱瞳孔大小与SRT之间的相关性，但头顶刺激时相关性保持不变。此外，与显著刺激相关的扫视和瞳孔反应之间的FEF刺激效应在不同参与者之间具有相关性。这是第一项关于瞳孔定向反应的经颅磁刺激（TMS）研究，我们的研究结果表明，人类FEF参与协调瞳孔大小和扫视，但不参与瞳孔定向反应的控制。
