Multisensory integration, which enhances stimulus saliency at the early stage of the processing hierarchy, has been recently shown to produce a larger pupil size than its unisensory constituents. Theoretically, any modulation on pupil size ought to be associated with the sympathetic and parasympathetic pathways that are sensitive to light. But it remains poorly understood how the pupillary light reflex is changed in a multisensory context. The present study evoked an oscillation of the pupillary light reflex by periodically changing the luminance of a visual stimulus at 1.25 Hz. It was found that such induced pupil size oscillation was substantially attenuated when the bright but not the dark phase of the visual flicker was periodically and synchronously presented with a burst of tones. This inhibition effect persisted when the visual flicker was task-irrelevant and out of attentional focus, but disappeared when the visual flicker was moved from the central field to the periphery. These findings not only offer a comprehensive characterization of the multisensory impact on pupil response to light, but also provide valuable clues about the individual contributions of the sympathetic and parasympathetic pathways to multisensory modulation of pupil size.

中文翻译：

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多感觉信号抑制瞳孔对光反射：来自瞳孔振荡的证据

多感官整合在处理层次结构的早期阶段增强了刺激的显着性，最近显示出比其非感官成分产生更大的瞳孔大小。从理论上讲，对瞳孔大小的任何调节都应该与对光敏感的交感神经和副交感神经通路有关。但在多感官环境中，瞳孔对光反射是如何改变的仍然知之甚少。本研究通过周期性地改变 1.25 Hz 的视觉刺激的亮度来引起瞳孔光反射的振荡。发现当视觉闪烁的亮而非暗阶段周期性地和同步地呈现与突发的音调时，这种诱导的瞳孔大小振荡显着减弱。当视觉闪烁与任务无关且注意力不集中时，这种抑制作用持续存在，但当视觉闪烁从中心区域移动到外围时，这种抑制作用就会消失。这些发现不仅提供了多感官对瞳孔对光反应的影响的全面表征，而且还提供了关于交感神经和副交感神经通路对瞳孔大小的多感官调节的个体贡献的有价值的线索。