Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Life Sciences Core Facilities Department, Weizmann Institute of Science, Rehovot, Israel.
Neuroimage. 2018 May 1;171:84-98. doi: 10.1016/j.neuroimage.2017.12.089. Epub 2017 Dec 30.
In the absence of a task, the human brain enters a mode of slow spontaneous fluctuations. A fundamental, unresolved question is whether these fluctuations are ongoing and thus persist during task engagement, or alternatively, are quenched and replaced by task-related activations. Here, we examined this issue in the human visual cortex, using fMRI. Participants were asked to either perform a recognition task of randomly appearing face and non-face targets (attended condition) or watch them passively (unattended condition). Importantly, in approximately half of the trials, all sensory stimuli were absent. Our results show that even in the absence of stimuli, spontaneous fluctuations were suppressed by attention. The effect occurred in early visual cortex as well as in fronto-parietal attention network regions. During unattended trials, the activity fluctuations were negatively linked to pupil diameter, arguing against attentional fluctuations as underlying the effect. The results demonstrate that spontaneous fluctuations do not remain unchanged with task performance, but are rather modulated according to behavioral and cognitive demands.
在没有任务的情况下，人类大脑会进入一种缓慢的自发波动模式。一个基本的、未解决的问题是，这些波动是持续的，因此在任务参与期间仍然存在，还是被抑制并被与任务相关的激活所取代。在这里，我们使用 fMRI 检查了人类视觉皮层中的这个问题。要求参与者执行一项识别任务，识别随机出现的人脸和非人脸目标（注意条件）或被动观看（不注意条件）。重要的是，在大约一半的试验中，所有的感觉刺激都不存在。我们的结果表明，即使没有刺激，注意力也会抑制自发波动。这种效应发生在早期视觉皮层以及额顶叶注意力网络区域。在不注意的试验中，活动波动与瞳孔直径呈负相关，这表明注意力波动不是该效应的基础。研究结果表明，自发波动不会随着任务表现而保持不变，而是根据行为和认知需求进行调节。
