when one of a kitten's eyes was sewn shut the main changes in the visual system affected the
Monocular deprivation David Hubel and Torsten Wiesel (who won the Nobel prize in Physiology for their elucidation of receptive field properties of cells in primary visual cortex) first performed the technique in felines.[1] Cats (or kittens), although less-closely related evolutionarily to humans even than rodents, have a remarkably similar visual system to humans. They found that ocular dominance columns (the orderly clustering of V1 neurons representing visual input from one or both eyes) were dramatically disrupted when one eye was sewn shut for 2 months. In the normal feline, about 85% of cells are responsive to input to both eyes; in the monocularly-deprived animals, no cells receive input from both eyes.[2]
Optic nerve The optic nerve leaves the orbit (eye socket) via the optic canal, running postero-medially towards the optic chiasm, where there is a partial decussation (crossing) of fibres from the temporal visual fields (the nasal hemi-retina) of both eyes. The proportion of decussating fibers varies between species, and is correlated with the degree of binocular vision enjoyed by a species.[4] Most of the axons of the optic nerve terminate in the lateral geniculate nucleus from where information is relayed to the visual cortex, while other axons terminate in the pretectal nucleus and are involved in reflexive eye movements. Other axons terminate in the suprachiasmatic nucleus and are involved in regulating the sleep-wake cycle. Its diameter increases from about 1.6 mm within the eye to 3.5 mm in the orbit to 4.5 mm within the cranial space. The optic nerve component lengths are 1 mm in the globe, 24 mm in the orbit, 9 mm in the optic canal, and 16 mm in the cranial space before joining the optic chiasm. There, partial decussation occurs, and about 53% of the fibers cross to form the optic tracts. Most of these fibres terminate in the lateral geniculate body.[1]