In our natural environment the senses are continuously flooded with a myriad of signals. To form a coherent representation of the world, the brain needs to integrate sensory signals arising from a common cause and segregate signals coming from separate causes. An unresolved question is how the brain solves this binding or causal inference problem and determines the causal structure of the sensory signals. In this functional magnetic resonance imaging (fMRI) study human observers (female and male) were presented with synchronous auditory and visual signals at the same location (i.e., common cause) or different locations (i.e., separate causes). On each trial, observers decided whether signals come from common or separate sources(i.e., "causal decisions"). To dissociate participants' causal inference from the spatial correspondence cues we adjusted the audiovisual disparity of the signals individually for each participant to threshold accuracy. Multivariate fMRI pattern analysis revealed the lateral prefrontal cortex as the only region that encodes predominantly the outcome of observers' causal inference (i.e., common vs separate causes). By contrast, the frontal eye field (FEF) and the intraparietal sulcus (IPS0–4) form a circuitry that concurrently encodes spatial (auditory and visual stimulus locations), decisional (causal inference), and motor response dimensions. These results suggest that the lateral prefrontal cortex plays a key role in inferring and making explicit decisions about the causal structure that generates sensory signals in our environment. By contrast, informed by observers' inferred causal structure, the FEF–IPS circuitry integrates auditory and visual spatial signals into representations that guide motor responses.

SIGNIFICANCE STATEMENT In our natural environment, our senses are continuously flooded with a myriad of signals. Transforming this barrage of sensory signals into a coherent percept of the world relies inherently on solving the causal inference problem, deciding whether sensory signals arise from a common cause and should hence be integrated or else be segregated. This functional magnetic resonance imaging study shows that the lateral prefrontal cortex plays a key role in inferring the causal structure of the environment. Crucially, informed by the spatial correspondence cues and the inferred causal structure the frontal eye field and the intraparietal sulcus form a circuitry that integrates auditory and visual spatial signals into representations that guide motor responses.

在我们的自然环境中，感官不断充斥着无数种信号。为了形成一个连贯的世界表示，大脑需要整合起因于共同原因的感觉信号，并分离起因于不同原因的信号。一个尚未解决的问题是大脑如何解决这种约束或因果推理问题，并确定感觉信号的因果结构。在这项功能磁共振成像（fMRI）研究中，人类观察者（女性和男性）在相同位置（即共同原因）或不同位置（即分开的原因）被呈现同步听觉和视觉信号。在每次试验中，观察者都决定信号是来自共同的还是分开的（即“因果关系决定”）。分离参与者的 从空间对应线索的因果推论，我们将每个参与者的信号视听视差分别调整为阈值精度。多元fMRI模式分析显示，外侧额叶前额叶皮层是唯一编码观察者因果推理结果的唯一区域（即常见原因与单独原因）。相比之下，额叶视场（FEF）和顶内沟（IPS0–4）形成了一个电路，该电路同时编码空间（听觉和视觉刺激位置），决定性（因果关系）和运动反应尺寸。这些结果表明，外侧前额叶皮层在推断和做出有关在我们环境中产生感觉信号的因果结构的决策方面起着关键作用。相比之下，由观察员

声明的意义在我们的自然环境，我们的感觉是连续被淹一个信号万千。将这一系列感觉信号转变为一个连贯的世界观，本质上取决于解决因果推理问题，确定感觉信号是否是由共同原因引起的，因此应予以整合或隔离。这项功能性磁共振成像研究表明，外侧前额叶皮层在推断环境的因果结构方面起着关键作用。至关重要的是，根据空间对应线索和推断的因果结构，前眼视野和顶内沟形成了一个电路，该电路将听觉和视觉空间信号整合为引导运动反应的表征。