Does action make the link between number and space representation? Visuo-manual adaptation improves number bisection...

If the visual world is artificially shifted by only 10 degrees, people initially experience difficulty in directing their actions toward visual goals, but then rapidly compensate the visual distortion. The consequence of such adaptation can be measured as visual and proprioceptive aftereffects, as well as by performance on pointing tasks without visual feedback. Recent work has shown that more cognitive deficits can be improved following prism adaptation in patients with unilateral neglect. Here we show that a short visuo-manual adaptation to prisms improves performance on a mental number-bisection task recently shown to be impaired in unilateral neglect. The association previously found between space and number representation (the mental number line) may thus be grounded in common action principles. Our results suggest that visuo-motor plasticity functionally links parietal areas involved in space and number representation.