The neural response to graspable food items in tool-selective visual cortex

Human occipitotemporal cortex is well-known to exhibit marked selectivity in neural response for several stimulus types including faces, bodies, places, tools, and words, each of which has a clear ecological importance for interacting with the world. Given this connection between visual category-selectivity and ecological importance, it is striking that no similarly unique selectivity has been reported in occipitotemporal cortex for visually-presented food, which is also thought to play an important role in survival. We hypothesized that this absence may be because food items are defined more by function (i.e., nutrition) than visual form. However, food items are often graspable and share many properties in common with tools, which are also defined primarily by function and used in stereotypical forms of action. In which case, differential neural responses to appropriately selected food items may be discernable in tool-selective cortex. To explore this hypothesis, we selected images of graspable food items (e.g., pizza slice, ice cream cone) and several tools, non-tool manipulable objects, and animals that were matched in global shape. An odd-one-out similarity judgment task revealed that the food items were indeed treated as distinct from the other stimulus types in our stimulus set. Yet, across several rating tasks (excluding animal images) related to the form and familiarity of action with the objects, we found that subjects considered food items more similar to tools than manipulable objects. Furthermore, using human fMRI, we found that a food > animal contrast revealed similar loci of activity to the standard tool > animal contrast in left lateral occipitotemporal cortex and that univariate and multivariate neural responses for food items in tool-selective cortex was again more similar to tools than manipulable objects. These results provide support for the hypothesis that visual cortex similarly represents tools and graspable food items.