The How and What of Object Knowledge in the Human Brain

Humans recognize, grasp, and manipulate objects on a daily basis. Critical to those behaviors is the ability to integrate information about visual structure, object function, and object-associated manipulation. This chapter reviews several lines of evidence that have documented a dissociation between representations of object function and representations of object manipulation. Drawing on a prior suggestion by Rothi, Heilman, and colleagues, the authors argue that this distinction runs parallel to a distinction made in the context of language processing, between abstract semantic representations of words and modality-specific representations of word forms. The studies that are reviewed in the chapter use a range of methods, including transcranial magnetic stimulation (TMS), functional magnetic resonance imaging (fMRI), and cognitive neuropsychological investigations of patients with brain injuries. The chapter also reviews studies on the functional and structural connectivity between temporal and parietal areas that are implicated in processing function and manipulation knowledge, respectively. It concludes by outlining key issues that lie ahead, emphasizing the role that connectivity-based measures will likely play in developing an explicit model of how the brain deploys the right actions to the right objects. The authors suggest that there are further lessons to be learned from models of lexical access in developing a computationally explicit model of object-directed action.