Abstract
Both eyes were closed in 12 kittens soon after birth, and one eye was reopened at 23 days. From 14 to 26 days later, the cells in the monocular segment of the LGN connected to the open eye became significantly larger than the corresponding cells on the other side of the brain that were connected to the eye that was still closed. Up to 26 days after eye opening, the response of the monocular segment was similar to that of the binocular segment, so the latter may not be dependent on mutual inhibition or competition between sets of cells connected to each eye. From 30 to 60 days after eye opening, however, there were no differences between the monocular segments, but marked differences between the binocular A laminae where mutual inhibition and competition can occur.
In seven more kittens both eyes were untouched until 23 days, when one eye was closed. Between 3 and 31 days later the deprived cells in the monocular segment of the LGN were not more than 8% smaller than those on the other side of the brain, and the measurements were not significantly different in any one cat. Within the binocular part of lamina A, cell growth is retarded by eye closure in two phases. Neither the early phase from 4โ6 days nor the later phase from 21 days onwards occurred in the monocular segment, so both may be dependent on mutual inhibition or competition between the sets of cells connected to each eye.
Two possible explanations of this difference between the effects of eye opening and eye closing are discussed.