Abstract
Human object recognition is supported by a robust representation of shape that is tolerant to variations in an object's appearance. Such 'global' shape representations are achieved by describing objects via the spatial arrangement of their local features, or structure, rather than by the appearance of the features themselves. Yet, despite its importance for object recognition, the neural mechanisms that support such robust representations of shape remain poorly understood. Here, I will present evidence that the dorsal visual pathway – the primary substrate underlying visuospatial processing and action – plays a crucial role in computing shape information for object recognition. Using fMRI, we find that the dorsal pathway contains regions selective for global shape, which are independent of regions that compute other properties represented by the dorsal pathway (e.g., allocentric relations). Moreover, the multivariate response within dorsal regions is sufficient to both categorize objects at levels comparable to the ventral pathway, as well as mediate representations of shape in the ventral pathway. These results are consistent with an emerging view of object processing, in which complete object representations are formed through the interactions of dorsal and ventral pathways. In this updated view, the ventral pathway is best described as a basis set of local image features, and shape information is, instead, computed by the dorsal pathway. In the final portion of the talk, I will review evidence for this new framework by drawing on neuroimaging data from different levels-of-analysis (single-unit, population-coding level), as well as data from neuropsychology patients.