Integrating information across different senses is a central feature of human perception. Previous research suggests that multisensory integration is shaped by a context-dependent and largely adaptive interplay between stimulus-driven bottom-up and top-down endogenous influences. One critical question concerns the extent to which this interplay is sensitive to the amount of available cognitive resources. In the present study, we investigated the influence of limited cognitive resources on audiovisual integration by measuring high-density electroencephalography (EEG) in healthy participants performing the sound-induced flash illusion (SIFI) and a verbal n-back task (0-back, low load and 2-back, high load) in a dual-task design. In the SIFI, the integration of a flash with two rapid beeps can induce the illusory perception of two flashes. We found that high compared with low load increased illusion susceptibility and modulated neural oscillations underlying illusion-related crossmodal interactions. Illusion perception under high load was associated with reduced early β power (18–26 Hz, ~70 ms) in auditory and motor areas, presumably reflecting an early mismatch signal and subsequent top-down influences including increased frontal power (7–9 Hz, ~120 ms) in mid-anterior cingulate cortex (ACC) and a later β power suppression (13–22 Hz, ~350 ms) in prefrontal and auditory cortex. Our study demonstrates that integrative crossmodal interactions underlying the SIFI are sensitive to the amount of available cognitive resources and that multisensory integration engages top-down and β oscillations when cognitive resources are scarce.

SIGNIFICANCE STATEMENT The integration of information across multiple senses, a remarkable ability of our perceptual system, is influenced by multiple context-related factors, the role of which is highly debated. It is, for instance, poorly understood how available cognitive resources influence crossmodal interactions during multisensory integration. We addressed this question using the sound-induced flash illusion (SIFI), a phenomenon in which the integration of two rapid beeps together with a flash induces the illusion of a second flash. Replicating our previous work, we demonstrate that depletion of cognitive resources through a working memory (WM) task increases the perception of the illusion. With respect to the underlying neural processes, we show that when available resources are limited, multisensory integration engages top-down and β oscillations.

整合不同感官的信息是人类感知的一个核心特征。先前的研究表明，多感官整合是由刺激驱动的自下而上和自上而下的内源性影响之间的上下文相关且很大程度上自适应的相互作用形成的。一个关键问题涉及这种相互作用对可用认知资源数量的敏感程度。在本研究中，我们通过测量执行声音诱发的闪光错觉 (SIFI) 和言语n 的健康参与者的高密度脑电图 (EEG) 来研究有限的认知资源对视听整合的影响。双任务设计中的 -back 任务（0-back，低负载和 2-back，高负载）。在 SIFI 中，一个闪光与两个快速哔哔声的结合可以诱发两个闪光的幻觉。我们发现，与低负载相比，高负载增加了错觉敏感性并调节了错觉相关交叉模式交互的潜在神经振荡。高负荷下的错觉与听觉和运动区域的早期β功率（18-26 Hz，~70 ms）降低有关，大概反映了早期不匹配信号和随后的自上而下的影响，包括增加的额叶功率（7-9 Hz， ~120 ms) 在中前扣带回皮层 (ACC) 和后来的 β 功率抑制 (13–22 Hz, ~350 ms) 在前额叶和听觉皮层。

意义声明跨多种感官的信息整合是我们感知系统的一项非凡能力，它受到多种与上下文相关的因素的影响，其作用备受争议。例如，人们对可用的认知资源如何影响多感官整合过程中的跨模式交互知之甚少。我们使用声音引起的闪光错觉 (SIFI) 解决了这个问题，这是一种将两次快速哔哔声与一次闪光结合在一起会诱发第二次闪光的错觉的现象。复制我们以前的工作，我们证明通过工作记忆 (WM) 任务消耗认知资源会增加对错觉的感知。关于潜在的神经过程，我们表明，当可用资源有限时，多感官整合参与自上而下和 β 振荡。