Monocular and binocular deprivation in the monkey: morphological effects and reversibility

Measurements were made of the cross-sectional area of neurons in the lateral geniculate nucleus (LGN) of normal monkeys, and of monkeys subjected to monocular and binocular eyelid suture. Early monocular deprivation caused a failure of normal cell growth in the LGN such that the neurons in the laminae innervated by the deprived eye were, on average, 15% smaller than those innervated by the normal eye. In the first 4 days of life monocular deprivation caused significant retardation of growth. The effect was marked in the first 6 weeks, but was not found in a monkey monocularly deprived from 11-16 months of age nor in an adult deprived for more than 6 months. Binocular deprivation from birth appeared to arrest neuronal growth at the neonatal size. The effect of monocular deprivation could be cancelled by 'reverse-suture' (opening the closed eye and closing the other) during the first 2 months of life. Changes in the size of LGN neurons following monocular deprivation and reverse-suture correlated closely with changes in the relative width of ocular dominance columns in layer IVc of area 17 of the visual cortex, measured physiologically in the same animals.