Reversal of the Effects of Visual Deprivation in Monkeys

Wiesel and Hubel (1963a,b) found that if the lids of one eye of a kitten were sutured closed soon after birth the neurons of the visual cortex, recorded by extracellular microelectrodes some weeks later, responded almost exclusively to the open eye, the deprived eye losing its ability to drive cortical units. This contrasted with normal cats in which some three-fourths of visual cortical cells were influenced binocularly (Hubel and Wiesel, 1963). Another effect of monocular lid suture was that the neurons in the lateral geniculate nucleus (LGN), innervated by the deprived eye failed to grow fully and were smaller than normally innervated cells. Hubel and Wiesel (1970) defined a “critical” or “sensitive” period from about three weeks to three months postnatally during which these effects could be elicited.


The primate visual system has also been studied with similar experimental procedures, and it has been found that monocular deprivation in the monkey also reduces cortical binocularity (Baker et al., 1974; Crawford et al., 1975; Hubel et al., 1977; Blakemore et al., 1978) and prevents normal neuronal growth in the LGN (Headon and Powell, 1973; von Noorden, 1973; Hubel et al., 1977; Vital-Durand et al., 1978).


In order to investigate the extent to which the changes due to monocular deprivation can be reversed, the technique of “reverse-suture” has been used. The animal is monocularly deprived until cortical and thalamic effects would be expected, and then the closed eye is reopened and the other closed. When done before about 6 weeks of age, in the cat, reverse-suture leads to “recapture” of cortical neurons by the initially deprived eye and to a total reversal of ocular dominance within about two weeks (Blakemore and Van Sluyters, 1974; Movshon, 1976). LGN cells, which are, in the cat, 30 to 40% smaller in cross-sectional area in histological sections in deprived laminae than in non-deprived, recover their size, and are as big as normal cells within three days. Within two weeks they are 30% larger than the newly deprived cells (Dürsteier et al., 1976).


We report here similar experiments performed in the monkey.