Perceptual rivalry of ambiguous stimuli reflects the interaction of neural activity among multiple cortical regions. However, it remains unclear what drives a spontaneous perceptual alteration. We hypothesized that increased fluctuations in spontaneous neural activity due to arousal reduction drive the perceptual switch. Here, we show that the pupils shrank a few seconds prior to the onset of the spontaneous perceptual switch. Such pupil constriction was not observed before the exogenous perceptual switch. Pharmacological experiments confirmed that the pupil constriction disappeared when the peripheral parasympathetic pathway (pupil sphincter muscle) was blocked, but it remained intact when the peripheral sympathetic pathway (pupil dilator muscle) was manipulated. Furthermore, rapid pupil dilations with behavioral response are also mediated by the peripheral parasympathetic pathway. The present findings suggested that transient arousal drops, as denoted by the autonomic nervous modulation of pupil size, are involved in inducing the spontaneous perceptual switch of bistable stimuli.

模糊刺激的感知竞争反映了多个皮层区域之间神经活动的相互作用。然而，目前尚不清楚是什么驱动了自发的感知改变。我们假设由于唤醒减少导致自发神经活动的波动增加驱动了知觉转换。在这里，我们表明学生在自发感知转换开始前几秒钟缩小了。在外源性知觉转换之前没有观察到这种瞳孔收缩。药理实验证实，当外周副交感神经通路（瞳孔括约肌）被阻断时，瞳孔收缩消失，但当外周交感神经通路（瞳孔扩张肌）被操纵时，瞳孔收缩保持完整。此外，伴随行为反应的快速瞳孔扩张也由外周副交感神经通路介导。目前的研究结果表明，短暂的觉醒下降，如瞳孔大小的自主神经调制所表示的，参与诱导双稳态刺激的自发感知转换。