Although there is mounting evidence that input from the dorsal visual pathway is crucial for object processes in the ventral pathway, the specific functional contributions of dorsal cortex to these processes remain poorly understood. Here, we hypothesized that dorsal cortex computes the spatial relations among an object's parts, a process crucial for forming global shape percepts, and transmits this information to the ventral pathway to support object categorization. Using fMRI with human participants (females and males), we discovered regions in the intraparietal sulcus (IPS) that were selectively involved in computing object-centered part relations. These regions exhibited task-dependent functional and effective connectivity with ventral cortex, and were distinct from other dorsal regions, such as those representing allocentric relations, 3D shape, and tools. In a subsequent experiment, we found that the multivariate response of posterior (p)IPS, defined on the basis of part-relations, could be used to decode object category at levels comparable to ventral object regions. Moreover, mediation and multivariate effective connectivity analyses further suggested that IPS may account for representations of part relations in the ventral pathway. Together, our results highlight specific contributions of the dorsal visual pathway to object recognition. We suggest that dorsal cortex is a crucial source of input to the ventral pathway and may support the ability to categorize objects on the basis of global shape.

SIGNIFICANCE STATEMENT Humans categorize novel objects rapidly and effortlessly. Such categorization is achieved by representing an object's global shape structure, that is, the relations among object parts. Yet, despite their importance, it is unclear how part relations are represented neurally. Here, we hypothesized that object-centered part relations may be computed by the dorsal visual pathway, which is typically implicated in visuospatial processing. Using fMRI, we identified regions selective for the part relations in dorsal cortex. We found that these regions can support object categorization, and even mediate representations of part relations in the ventral pathway, the region typically thought to support object categorization. Together, these findings shed light on the broader network of brain regions that support object categorization.

尽管有越来越多的证据表明背侧视觉通路的输入对于腹侧通路中的物体过程至关重要，但背侧皮层对这些过程的具体功能贡献仍然知之甚少。在这里，我们假设背侧皮层计算物体各部分之间的空间关系，这是形成全局形状感知的关键过程，并将这些信息传输到腹侧通路以支持物体分类。通过对人类参与者（女性和男性）进行功能磁共振成像，我们发现顶内沟 (IPS) 中的区域选择性地参与计算以对象为中心的部分关系。这些区域表现出与腹侧皮层的任务依赖性功能和有效连接，并且与其他背侧区域不同，例如代表同种中心关系、3D 形状和工具的区域。在随后的实验中，我们发现基于部分关系定义的后部 (p)IPS 的多元响应可用于解码与腹侧物体区域相当的水平上的物体类别。此外，中介和多变量有效连接分析进一步表明 IPS 可能解释了腹侧通路中部分关系的表示。总之，我们的结果强调了背侧视觉通路对物体识别的具体贡献。我们认为背侧皮层是腹侧通路输入的重要来源，并且可能支持根据整体形状对物体进行分类的能力。

意义陈述人类可以快速、毫不费力地对新事物进行分类。这种分类是通过表示对象的全局形状结构（即对象各部分之间的关​​系）来实现的。然而，尽管它们很重要，但目前尚不清楚部分关系如何在神经上表示。在这里，我们假设以对象为中心的部分关系可以通过背侧视觉通路来计算，这通常涉及视觉空间处理。使用功能磁共振成像，我们确定了背侧皮质中对部分关系具有选择性的区域。我们发现这些区域可以支持对象分类，甚至可以调解腹侧通路中部分关系的表示，该区域通常被认为支持对象分类。总之，这些发现揭示了支持物体分类的更广泛的大脑区域网络。