Uncovering the nature of object representations in the human dorsal visual cortex

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The human visual system enables us to recognize objects (e.g., this is a cup) and act upon them (e.g., grasp the cup) with astonishing ease and accuracy. For decades, it was widely accepted that these different functions rely on separated cortical pathways. In particular, the ventral pathway subserves object recognition, while the dorsal pathway subserves visually guided actions. However, recent evidence challenges this binary distinction and suggests that regions in the dorsal “action” pathway also derive shape representations that play a role in object perception. ******Despite this recent progress, the nature of shape representations derived by the dorsal pathway is still unclear. One major challenge in elucidating these representations is that they are modulated by a variety of factors, such as (a) the inputs from other brain regions, (b) task demands and (c) the physical features of the stimulus. Thus, the overarching goal of this research program is to shed light on the nature of dorsal shape representations by contemplating the extent to which different factors modulate these representations. In two complementary projects, we will address these questions, by utilizing a variety of state-of-the-art behavioural and neuroimaging techniques.*The first project will examine whether independent shape representations are computed by the dorsal pathway, even when inputs from the ventral pathway are minimized. To this end, we will utilize experimental techniques which are designed explicitly to bias shape processing to the dorsal pathway. The main prediction is that despite the interconnections between the two pathways, the dorsal pathway derives independent shape representations.******The second project will probe the degree to which task demands modulate dorsal shape representations. To that purpose, a variety of tasks, which require the processing of different shape attributes, will be employed, while the visual input will be kept constant. We predict that despite an automatic sensitivity of the dorsal pathway to shape information, dorsal representations will be modulated by task demands, particularly for tasks that involve spatial processing. ******Together, this research program has the potential to elucidate the neural underpinnings of shape perception, a fundamental perceptual ability. Moreover, these insights might shed light on the underlying mechanisms of congenital and acquired disorders in which visual perception is impaired.