title: Motion along the mental number line reveals shared representations for numerosity and space.
abstract: Perception of number and space are tightly intertwined. It has been proposed that this is due to 'cortical recycling', where numerosity processing takes over circuits originally processing space. Do such 'recycled' circuits retain their original functionality? Here, we investigate interactions between numerosity and motion direction, two functions that both localize to parietal cortex. We describe a new phenomenon in which visual motion direction adapts nonsymbolic numerosity perception, giving rise to a repulsive aftereffect: motion to the left adapts small numbers, leading to overestimation of numerosity, while motion to the right adapts large numbers, resulting in underestimation. The reference frame of this effect is spatiotopic. Together with the tuning properties of the effect this suggests that motion direction-numerosity cross-adaptation may occur in a homolog of area LIP. 'Cortical recycling' thus expands but does not obliterate the functions originally performed by the recycled circuit, allowing for shared computations across domains.
authors.affiliation: Laboratory of Neural Systems, The Rockefeller University, New York, United States.
authors.forename: Caspar M
authors.identifier: http://orcid.org/0000-0003-0661-8859
authors.initials: CM
authors.lastname: Schwiedrzik
authors.affiliation: Department of Psychology, Northwestern University, Evanston, United States.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bernstein
authors.affiliation: Department of Neurophysiology, Max Planck Institute for Brain Research, Frankfurt am Main, Germany.|Department of Neurosurgery, Columbia University College of Physicians and Surgeons, New York, United States.|Department of Neurology, New York University Langone Medical Center, New York, United States.
authors.forename: Lucia
authors.identifier: http://orcid.org/0000-0001-8743-5071
authors.initials: L
authors.lastname: Melloni
mesh_terms: D001931:Brain Mapping; D003071:Cognition; D055641:Mathematical Concepts; D009038:Motion; D010296:Parietal Lobe / Q000502:physiology*; D010775:Photic Stimulation; D013028:Space Perception
keywords: adaptation; cortical recycling; human; neuroscience; numerical cognition; parietal cortex; visual motion