Kloosterman Niels A, Meindertsma Thomas, van Loon Anouk M, Lamme Victor A F, Bonneh Yoram S, Donner Tobias H
Department of Psychology, University of Amsterdam, Weesperplein 4, Amsterdam, 1018XA, the Netherlands; Amsterdam Center for Brain and Cognition, Institute for Interdisciplinary Studies, University of Amsterdam, Amsterdam, the Netherlands.
Eur J Neurosci. 2015 Apr;41(8):1068-78. doi: 10.1111/ejn.12859. Epub 2015 Mar 6.
Changes in pupil size at constant light levels reflect the activity of neuromodulatory brainstem centers that control global brain state. These endogenously driven pupil dynamics can be synchronized with cognitive acts. For example, the pupil dilates during the spontaneous switches of perception of a constant sensory input in bistable perceptual illusions. It is unknown whether this pupil dilation only indicates the occurrence of perceptual switches, or also their content. Here, we measured pupil diameter in human subjects reporting the subjective disappearance and re-appearance of a physically constant visual target surrounded by a moving pattern ('motion-induced blindness' illusion). We show that the pupil dilates during the perceptual switches in the illusion and a stimulus-evoked 'replay' of that illusion. Critically, the switch-related pupil dilation encodes perceptual content, with larger amplitude for disappearance than re-appearance. This difference in pupil response amplitude enables prediction of the type of report (disappearance vs. re-appearance) on individual switches (receiver-operating characteristic: 61%). The amplitude difference is independent of the relative durations of target-visible and target-invisible intervals and subjects' overt behavioral report of the perceptual switches. Further, we show that pupil dilation during the replay also scales with the level of surprise about the timing of switches, but there is no evidence for an interaction between the effects of surprise and perceptual content on the pupil response. Taken together, our results suggest that pupil-linked brain systems track both the content of, and surprise about, perceptual events.
在恒定光照水平下瞳孔大小的变化反映了控制整体脑状态的神经调节脑干中枢的活动。这些内源性驱动的瞳孔动态变化可以与认知行为同步。例如，在双稳态知觉错觉中，当对恒定感觉输入的知觉自发切换时，瞳孔会扩张。目前尚不清楚这种瞳孔扩张仅仅是表明知觉切换的发生，还是也表明其内容。在这里，我们测量了人类受试者的瞳孔直径，这些受试者报告了一个被移动图案包围的物理上恒定的视觉目标（“运动诱导失明”错觉）的主观消失和重新出现。我们发现，在错觉中的知觉切换以及该错觉的刺激诱发“重现”过程中，瞳孔会扩张。至关重要的是，与切换相关的瞳孔扩张对知觉内容进行了编码，消失时的幅度大于重新出现时的幅度。瞳孔反应幅度的这种差异使得能够对个体切换时的报告类型（消失与重新出现）进行预测（接受者操作特征曲线：61%）。幅度差异与目标可见和目标不可见间隔的相对持续时间以及受试者对知觉切换的明显行为报告无关。此外，我们表明，在重现过程中瞳孔扩张也与对切换时间的惊讶程度成比例，但没有证据表明惊讶和知觉内容对瞳孔反应的影响之间存在相互作用。综上所述，我们的结果表明，与瞳孔相关的脑系统跟踪知觉事件的内容以及对这些事件的惊讶程度。
