title: Global motion coherence can influence the representation of ambiguous local motion.
abstract: Early cortical responses to visual motion are inherently ambiguous as to underlying motion in the world. This ambiguity derives from the fact that directionally selective cells in early visual areas, such as V1, can predominantly signal only 1D motion orthogonal to image contours spanning their small, spatially localized, receptive fields. One way in which local ambiguity could be overcome is by integrating motion signals over orientation and space. Here, we show that the direction of an aftereffect produced by ambiguous local motion signals is modified to be more consistent with the global motion of which the local signals were part. This suggests an architecture whereby directionally selective cells in early cortical areas both project to and receive feedback from cells with large receptive fields that integrate local motion signals to respond to global "object" motion. This type of architecture could satisfy the competing needs to integrate information to resolve ambiguity but, at the same time, maintain the local spatial precision required to represent motion boundaries and features. The perceived direction of motion is therefore an adaptive interplay between both the measurable local signal and its inferred cause.
authors: Department of Cognitive, Perceptual and Brain Sciences, University College London, UK. p.scarfe@ucl.ac.uk
authors: Peter
authors: P
authors: Scarfe
authors: Alan
authors: A
authors: Johnston
mesh_terms: D005556:Form Perception / Q000502:physiology*; D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D009949:Orientation; D010775:Photic Stimulation / Q000379:methods; D014793:Visual Cortex / Q000502:physiology*