Abstract
In the present study the size of large samples of cells and the relative frequency of Y‐cells were measured in the lateral geniculate nucleus of monocularly‐deprived and reverse‐sutured cats. Due to deprivation large cells shrink more than smaller cells. This shrinkage is irreversible even over two years of reverse suture although over the same time the animals showed a remarkable pattern discrimination ability, which, in these animals, depends on the integrity of the geniculo‐cortical system. Physiologically, a significant increase in the probability of recording Y‐cells in the early‐deprived laminae of the LGNd was found after a reverse suture. The relative frequency of Y‐cells in the earlydeprived layers and in the late‐deprived layers was almost equal and not different from normal, although after the early deprivation by itself only 20% Y‐cells were found in the deprived layers. The latter results confirm our previous observation (Sherman et al., '72). The increase in the number of recorded Y‐cells following a reverse suture after monocular deprivation is accompanied by only small changes in the distribution of cell sizes in the LGNd. The number of very large cells in the early‐deprived layers was increased but the mean cell size remained unaltered after long forced usage of the deprived eye.