Development of visual cortical orientation specificity after dark-rearing: role of extraocular proprioception

Six-week-old dark reared kittens exposed to light for 6 h: (1) with head and body tightly cast into plaster; or (2) free to move around in the animal room. A few days before the visual experience, the ophthalmic branch of the 5th nerve was severed bilaterally in experimental kittens, in order to suppress most of the proprioceptive afferents from extraocular muscles. Electrophysiological analysis of the properties of the receptive fields of visual cortical cells shows that only 6% (group 1) and 11% (group 2) of the cells were selective to orientation as opposed to 67% (group 1) or 32% (group 2) observed in the non-operated kittens.