an experimental paradigm in which an animal is raised from birth with vision restricted to one eye by suturing the eyelids closed or by inserting an opaque contact lens in one eye. Monocular rearing during the critical period has profound structural and functional consequences for the developing visual system, including a shift in the ocular dominance of cortical neurons to favor the nonoccluded eye and a broadening of the ocular dominance columns corresponding to the open eye.