Dynamic representations of visual space for perception and action

Abstract

The division of labor in visual processing between two anatomically relatively separate cortical pathways, a ventral and a dorsal stream, has been hotly debated in the last decades. One influential model is the What & How pathway model, suggesting that the separation is along ventral perception versus dorsal action, although the degree of functional separation between the two streams is controversial. An implication of this model is that perception and memory-guided movements are highly sensitive to visual contextual illusions, whereas visually-guided movements are largely immune to them. Here, we summarize our recent behavioral and imaging data obtained in single and double saccade paradigms that test this proposal, with a focus on the role of time in visuomotor processing and updating. We describe results showing that presentation time of the illusion affects both saccade amplitude and perceptual judgments in a similar way. We also discuss behavioral findings showing that visuomotor updating is affected by illusory context. Complementary neuroimaging data suggest a neural correlate of these findings in dorsal stream areas. Taken together, these results are suggestive of a dynamic, common visual representation that drives both perception and action, or - at least - that there is no absolute functional specialization of the two visual processing streams.

Keywords: Illusions; Parietal; Saccades; Spatial updating; fMRI.