IMPLANTATION OF ARTIFICIAL WHISKERS ON THE EARS OF NEWBORN MICE INDUCES VISUAL RE-MAPPING IN THE SUPERIOR COLLICULUS

In newborn mice, we modified the body scheme by implanting artificial whiskers (pig hair) on the ears, which are located in the superior and temporal portions of the visual field. In normal mice, multisensory n eurons in the deep layers of the superior colliculus receiving somatos ensory input from the ears showed visual receptive fields in the super ior and temporal portions of visual space. By contrast, in the implant ed mice, there was a modification of the visual receptive fields stric tly related to the direction of the artificial whiskers. If these were directed toward the nose, visual receptive fields expanded in the nas al direction. If the whiskers were directed downward, visual receptive fields expanded downward. These results show that an interaction betw een visual and somatosensory inputs occurs in the superior colliculus during development, and that the collicular visual topography undergoe s a re-mapping on the basis of the altered tactile experience.