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 neurons in the deep layers of the superior colliculus receiving somatosensory input from the ears showed visual receptive fields in the superior and temporal portions of visual space. By contrast, in the implanted mice, there was a modification of the visual receptive fields strictly related to the direction of the artificial whiskers. If these were directed toward the nose, visual receptive fields expanded in the nasal direction. If the whiskers were directed downward, visual receptive fields expanded downward. These results show that an interaction between visual and somatosensory inputs occurs in the superior colliculus during development, and that the collicular visual topography undergoes a re-mapping on the basis of the altered tactile experience.