Abstract
When we perceive an object (e.g., a hammer), much information about the object is processed (e.g., its shape, kind, or function). How are the different aspects of information processed in the distributed category-selective networks? While tool-selective regions in the occipitotemporal cortex primarily contain categorical information about tools, compared with visual information (e.g., shape or spatial frequency, He et al., 2020), here we used fMRI to examine 1) how category and visual information may be represented in the parietal cortex, and 2) whether regions with increased similarity in the representational content are also more strongly connected functionally. Tool-selective regions in left superior and inferior parietal lobules (SPL/IPL) were first defined with images of animals and tools with naturally varied image statistics. We then tested the nature of representations in these regions with images of animals and tools that were either round or elongated, and either in low or high spatial frequencies (LSF/HSF). Importantly, these images shared comparable gist statistics, minimizing low- or mid-level visual differences across the categories. Using representational similarity analysis, we found that tool category and HSF information were independently represented in SPL, whereas elongation and HSF information interacted in IPL. Interestingly, functional connectivity analysis suggested that the tool category representation in SPL might be related to the stronger connectivity between tool-selective left medial fusiform gyrus and SPL, compared with IPL, and that the elongation representation in IPL might be related to the stronger connectivity between tool-selective left premotor region and IPL, compared with SPL. Together, these results showed that the complementary approaches of functional connectivity and representational similarity analyses can provide useful insights on the respective roles and interactions among regions in category-selective networks, such as how different aspects of tool information are represented in various regions in the tool-selective network to support recognition and potential action planning.