Vision influences paw-preference in mice

We studied the influence of vision on the expression of handedness in mice. In one experiment we submitted adult mice that had an opaque scleral contact lens fitted to one eye, to a paw-preference testing procedure. When the eye was occluded before training, the animals showed a clear preference for the paw ipsilateral to the open eye; however, we could not induce a shift in a previously determined, natural, paw-preference when the lens was placed over the eye ipsilateral to the spontaneously preferred paw; these results indicate that vision plays a role in the animal's choice of a paw during the learning phase of the paw-preference test. In a second experiment adult mice that had been subjected to unilateral eye removal at birth, underwent the same test. The enucleation did not appear to influence handedness with respect to both direction and strength. The latter result--we propose--reflects a reorganization of the visual system induced by neonatal enucleation.