Neuroscience Institute and Psychology Department, Carnegie Mellon University, Pittsburgh, PA 15213
J Neurosci. 2022 Jun 8;42(23):4693-4710. doi: 10.1523/JNEUROSCI.2257-21.2022. Epub 2022 May 4.
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. 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.
尽管越来越多的证据表明，来自背侧视觉通路的输入对腹侧通路中的物体加工至关重要，但背侧皮层对这些过程的具体功能贡献仍知之甚少。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，这是形成整体形状感知的关键过程，并将此信息传递到腹侧通路以支持物体分类。我们使用功能磁共振成像技术（fMRI）对人类参与者（女性和男性）进行了研究，发现了顶内沟（IPS）中的区域，这些区域专门参与计算以物体为中心的部分关系。这些区域与腹侧皮层表现出任务相关的功能和有效连接，并且与其他背侧区域（例如代表非定向关系、3D 形状和工具的区域）不同。在随后的实验中，我们发现，基于部分关系定义的后顶内沟（pIPS）的多元响应可以用于解码与腹侧物体区域相当的物体类别。此外，中介和多元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，我们的研究结果强调了背侧视觉通路对物体识别的特定贡献。我们认为，背侧皮层是腹侧通路的重要输入源，可能支持基于整体形状对物体进行分类的能力。人类可以快速而轻松地对新物体进行分类。这种分类是通过表示物体的整体形状结构，即物体各部分之间的关系来实现的。然而，尽管它们很重要，但神经如何表示部分关系尚不清楚。在这里，我们假设以物体为中心的部分关系可能由背侧视觉通路计算，该通路通常与视空间处理有关。使用 fMRI，我们确定了背侧皮层中对部分关系具有选择性的区域。我们发现，这些区域可以支持物体分类，甚至可以介导腹侧通路中部分关系的表示，腹侧通路通常被认为支持物体分类。这些发现共同揭示了支持物体分类的更广泛的大脑区域网络。
