Evidence for a role of calcineurin in the development of retinocollicular fine topography

▶ Calcineurin expression peaks at the time of eye opening (PND14). ▶ Treatment with calcineurin inhibitors disrupts retinotectal topography. ▶ Axons were found at ectopic loci in the superior colliculus. ▶ CaN activity is necessary for use-dependent sharpening of visual connections.