Timing of the Critical Period for Plasticity of Ocular Dominance Columns in Macaque Striate Cortex

Abstract

Visual deprivation induced by monocular eyelid suture, a laboratory model for congenital cataract, results in shrinkage of ocular dominance columns serving the closed eye. We performed monocular suture in macaques at ages 1, 3, 5, 7, and 12 weeks to define the critical period for plasticity of ocular dominance columns. After a minimum survival of 8 months, complete montages of [ 3 H]proline-labeled columns were reconstructed from flat-mounts of striate cortex in both hemispheres. In any given monkey, visual deprivation induced the columns throughout striate cortex (V1) to retract the same distance from their original borders in layer IVc␤. After deprivation, the widest columns remained in the foveal representation and along the V1/V2 border, where columns are widest in control animals. The narrowest deprived columns belonged to the ipsilateral eye, especially along the horizontal meridian and in the periphery, where columns are narrowest in control animals. At the earliest age that we tested (1 week), visual deprivation reduced the columns to fragments. These fragments always coincided with a cytochrome oxidase patch, or a short string of patches, in the upper layers. More severe column shrinkage occurred in layer IVc␤ (parvo) than layer IVc␣ (magno). The geniculate input to the patches in layer III (konio) appeared normal after deprivation, despite loss of CO activity. Surprisingly, the blind spot representation of the open eye was shrunken by monocular deprivation, although binocular competition is absent in this region. Our principal finding was that eyelid suture at age 1 week caused the most severe column shrinkage. With suture at later ages, the degree of column shrinkage showed a progressive decline. Deprivation commencing at age 12 weeks caused no column shrinkage. These results imply that primate visual cortex is most vulnerable to deprivation during the first weeks of life. Our experiments should provide further impetus for the treatment of children with congenital cataract at the earliest possible age.

Large-scale remapping of visual cortex is absent in adult humans with macular degeneration

“…Seminal work on early visual deprivation in animals has shown that visual cortex can develop to devote more of its territory to intact visual input at the expense of its representation of impoverished input [32][33][34][35] . Such reallocation of cortical processing has also been demonstrated when early visual areas remap following congenital retinal lesions in human 6 .…”

Amblyopia after unilateral infantile cataract extraction after six weeks of age

“…The harmful effects of unilateral visual deprivation to genicule-cortical architecture begins in the first week of life, with more severe cortical columns fragmentations in animal models the earlier the deprivation begins (17)(18)(19) .…”

Spinogenesis and Pruning Scales across Functional Hierarchies

“…We used one animal for each age (Table 1). These time points were chosen according to the following rationale: 2D postnatal was the youngest animal we could obtain, 3 weeks of age correlates with the window of the critical period of ocular dominance shift according to Horton and Hocking (1997), 3.5 months of age corresponds to the peak of spine density according to Rakic et al (1986) and the end of the critical period according to Horton and Hocking (1997), 7 months of age corresponds to double this time, and 4.5 years corresponds to young adulthood.…”