The brain is capable of integrating signals from multiple sensory modalities. Such multisensory integration can occur in areas that are commonly considered unisensory, such as planum temporale (PT) representing the auditory association cortex. However, the roles of different afferents (feedforward vs. feedback) to PT in multisensory processing are not well understood. Our study aims to understand that by examining laminar activity patterns in different topographical subfields of human PT under unimodal and multisensory stimuli. To this end, we adopted an advanced mesoscopic (sub-millimeter) fMRI methodology at 7 T by acquiring BOLD (blood-oxygen-level-dependent contrast, which has higher sensitivity) and VAPER (integrated blood volume and perfusion contrast, which has superior laminar specificity) signal concurrently, and performed all analyses in native fMRI space benefiting from an identical acquisition between functional and anatomical images. We found a division of function between visual and auditory processing in PT and distinct feedback mechanisms in different subareas. Specifically, anterior PT was activated more by auditory inputs and received feedback modulation in superficial layers. This feedback depended on task performance and likely arose from top-down influences from higher-order multimodal areas. In contrast, posterior PT was preferentially activated by visual inputs and received visual feedback in both superficial and deep layers, which is likely projected directly from the early visual cortex. Together, these findings provide novel insights into the mechanism of multisensory interaction in human PT at the mesoscopic spatial scale.

大脑能够整合来自多种感觉方式的信号。这种多感觉整合可以发生在通常被认为是非感觉的区域，例如代表听觉关联皮层的颞平面 (PT)。然而，不同传入（前馈与反馈）对 PT 在多感官处理中的作用尚不清楚。我们的研究旨在通过在单峰和多感觉刺激下检查人类 PT 不同地形子域的层流活动模式来理解这一点。为此，我们在 7 T 下采用了先进的介观（亚毫米）功能磁共振成像方法，通过获取 BOLD（血氧水平依赖性对比，具有更高的灵敏度）和 VAPER（综合血容量和灌注对比，具有优越的层流特异性）信号同时，并受益于功能图像和解剖图像之间的相同采集，在原生 fMRI 空间中进行了所有分析。我们发现 PT 中视觉和听觉处理之间的功能划分以及不同子区域中不同的反馈机制。具体来说，前部 PT 更多地由听觉输入激活，并在表层接受反馈调制。这种反馈取决于任务绩效，并且可能来自高阶多模式区域的自上而下的影响。相比之下，后部 PT 优先由视觉输入激活，并在浅层和深层接收视觉反馈，这可能直接从早期视觉皮层投射。总之，这些发现为在介观空间尺度上人类 PT 的多感官相互作用机制提供了新的见解。