Human Microsaccade-Related Visual Brain Responses
Human Microsaccade-Related Visual Brain Responses
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DOI：
10.1523/jneurosci.0911-09.2009
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发表时间：
2009-09-30
影响因子：
5.3
通讯作者：
Kliegl, Reinhold
中科院分区：
文献类型：
--
作者：
Dimigen, Olaf;Valsecchi, Matteo;Kliegl, Reinhold
微扫视是一种非常小的、不自觉的眼球运动，在试图注视时平均每秒发生一到两次。微眼跳会引起肌电图的眼球肌肉尖峰，这会扭曲头皮脑电图的频谱，并模拟伽马波段功率的增加。在这里，我们证明了微跳也伴随着真正的和相当大的皮层活动，在脑电图中表现出来。在三个实验中，高分辨率的眼球运动与脑电图同步记录：在持续注视棋盘和面部刺激时，以及在需要计数目标刺激的标准视觉怪球任务中。结果表明，小至0.15度的微眼跳在运动开始后100-140 ms在枕皮质和头皮中央区产生场电位，这与较大的自发性眼跳引起的视觉lambda反应相似。这挑战了人脑成像研究的标准假设，即眼珠相关的大脑活动被固定排除，即使完全符合。相反，在86%的古怪任务试验中，微跳产生的额外皮层电位存在，其振幅与刺激开始时的视觉反应相似。此外，微跳概率会根据古怪任务中目标刺激的比例发生系统变化，从而导致刺激锁定事件相关电位（ERP）成分的调节。微跳呈现出一种未被识别的视觉脑信号来源，这是视觉研究的兴趣所在，可能影响了许多ERP和神经影像学研究的数据。
Microsaccades are very small, involuntary flicks in eye position that occur on average once or twice per second during attempted visual fixation. Microsaccades give rise to EMG eye muscle spikes that can distort the spectrum of the scalp EEG and mimic increases in gamma band power. Here we demonstrate that microsaccades are also accompanied by genuine and sizeable cortical activity, manifested in the EEG. In three experiments, high-resolution eye movements were corecorded with the EEG: during sustained fixation of checkerboard and face stimuli and in a standard visual oddball task that required the counting of target stimuli. Results show that microsaccades as small as 0.15 degrees generate a field potential over occipital cortex and midcentral scalp sites 100-140 ms after movement onset, which resembles the visual lambda response evoked by larger voluntary saccades. This challenges the standard assumption of human brain imaging studies that saccade-related brain activity is precluded by fixation, even when fully complied with. Instead, additional cortical potentials from microsaccades were present in 86% of the oddball task trials and of similar amplitude as the visual response to stimulus onset. Furthermore, microsaccade probability varied systematically according to the proportion of target stimuli in the oddball task, causing modulations of late stimulus-locked event-related potential (ERP) components. Microsaccades present an unrecognized source of visual brain signal that is of interest for vision research and may have influenced the data of many ERP and neuroimaging studies.