Ordered arrangement of orientation columns in monkeys lacking visual experience

Abstract

The main object of this study was to see whether ordered sequences of orientation columns are present in very young visually naive monkeys. Recordings were made from area 17 in two macaque monkeys three and four weeks of age, whose eyes had been closed near the time of birth. The first monkey was born normally, but one day elapsed before eye closure could be done. The second was delivered by Cesarean section and the lids sutured shut immediately. The results in these two animals were very similar; in both, highly ordered sequences of orientation shifts were present, and were in no obvious way different from those seen in the adult. For example, average values for the size of orientation shifts, for the horizontal component of the distance between shifts, and for the slopes of orientation vs. track distance curves, were all similar to adult values. This indicates that the ordered column system is innately determined and not the result of early visual experience. In these two monkeys and a third one, sutured at two days and examined at 38 days, most of the cells seemed normal by adult standards, with simple, complex or hypercomplex receptive fields, showing about the same range in orientation specificity as is found in adults. About 10–15% of cells showed abnormalities similar to those seen in monkeys binocularly deprived of vision for longer periods. Furthermore, all three deprived monkeys showed a decided lack of cells that could be influenced from both eyes, whereas a normal three‐week‐old control animal seemed similar to the adult, with binocular cells comprising over half of the total population. A monkey deprived by binocular closure from the third to the seventh week also showed a diminution in number of binocularly influenced cells, suggesting that the deprivation from birth resulted in a deterioration of innate connections subserving binocular convergence. To be sure that the abnormalities in the deprived animals represented a deterioration of connections, we recorded from 23 cells in a normal two‐day‐old monkey: here the ocular dominance distribution of cells was about the same as in the adult, and the response characteristics of the cells were normal by adult standards.