State time courses data shown in S1 Fig.

Why do we sometimes perceive a faint stimulus but miss it at other times? One explanation is that fluctuations in the brain’s internal state result in variability in perception. Ongoing neural oscillations in the alpha band (8–13 Hz), crucial in setting the internal state of the brain, have been shown as a key contributor to such perceptual variability. However, findings on how alpha oscillations modulate perceptual variability have been mixed. Some studies suggested alpha modulates perceptual criterion (c), shifting the threshold for interpreting sensory information; while others suggested alpha modulates sensitivity (d′), changing the precision of sensory encoding. Moreover, most studies have focused solely on overall alpha activity—whether within a region of interest or across the whole brain—and overlooked the coexistence of multiple distinct alpha networks, leaving it unclear whether different alpha networks contribute differently to perception. Here, to characterize how different alpha networks influence perceptual decision-making, we analyzed magnetoencephalography (MEG) data recorded while human participants performed a visual detection task with threshold-level stimuli. We found that while the visual alpha network modulates sensitivity, the sensorimotor alpha network modulates criterion in perceptual decision-making. These findings reconcile previous conflicting results and highlight the functional diversity of alpha networks in shaping perception.

为何我们有时能感知到微弱刺激，有时却会错过它？对此的一种解释是，大脑内部状态的波动会导致感知的变异性。对大脑内部状态调控至关重要的持续性α频段（alpha band，8–13 Hz）神经振荡，已被证实是这类感知变异性的关键诱因。然而，关于α频段神经振荡如何调控感知变异性的研究结论却存在分歧：部分研究指出α振荡调控感知判别标准（c），即改变解读感官信息的阈值；而另一些研究则认为α振荡调控感知灵敏度（d′），即改变感官编码的精度。此外，绝大多数研究仅关注整体α活动——无论是特定脑区还是全脑范围——却忽略了多个不同α网络的共存性，因此无法明确不同α网络对感知的贡献是否存在差异。本研究为阐明不同α网络如何影响感知决策，分析了人类被试完成阈值级视觉检测任务时记录的脑磁图（magnetoencephalography，MEG）数据。我们发现，视觉α网络调控感知灵敏度，而感觉运动α网络则调控感知决策中的判别标准。本研究结果调和了此前的矛盾结论，并凸显了α网络在塑造感知过程中的功能多样性。