The development of orientation and direction selectivity in the rabbit visual cortex.

The postnatal development of orientation and direction selectivity of single cells was examined in the primary visual cortex of rabbits. The percentage of cells which were orientation-selective reached adult levels by day 30, whereas the proportion of cells which were direction-selective did not reach adult levels until day 60. Differences in the time course of development of orientation and direction selectivity, together with data previously reported on differences in the effects of deprivation on orientation and direction selectivity, suggest that (1) different mechanisms underly the organization of orientation and direction selectivity and (2) the critical periods for the effects of deprivation on orientation and direction selectivity reflect the different time course of the normal development of these two response properties.