Grasping at the organization of object knowledge: testing different object–related dimensions as organizational principles of ventral temporal cortex

In our daily lives we encounter a myriad of things with which we interact when navigating our environment. Mental representations of these things are computed and stored in our brains to be manipulated in support of cognition. Several proposals have been put forth on how such representations are organized in the brain – and specifically within ventral temporal cortex (VTC), which is thought to support object recognition. Some propose that the organization of mental representations tracks the animacy status of target stimuli in a continuous way: high–animacy stimuli (e.g., chimps) are represented farther from artifacts (e.g., hammers) than low–animacy stimuli (e.g., lobsters). Others emphasize the role of different dimensions in the organization of mental representations, including real–object size, shape, texture and material properties, and graspability. Here we used functional magnetic resonance imaging (fMRI) and multivariate approaches to test the role of these dimensions as organizing principles of object information in VTC. We show that pattern discriminability between different categories of objects does not seem to follow differences in animacy status in any continuous way. Moreover, graspability and haptic texture properties are better predictors of representational content within VTC than animacy and real–object size. Our results align with evidence that object processing depends on bidirectional functional coupling between parietal regions involved in manipulation and grasping and VTC regions involved in material/texture processing. This supports a multidimensional account of object representations in VTC, where action–relevant and haptic/material properties contribute strongly to representational structure, potentially through interactions with distal regions involved in object–directed action.