N-methyl-D-aspartate subunit R1 involvement in the postnatal organization of the primary visual cortex of Callithrix...

It has been demonstrated that the primary visual cortex is highly sensitive to manipulations of the visual environment during a specific, early, postdevelopmental period: the critical period. Pharmacological studies have shown that N-methyl-D-aspartate (NMDA) receptors are involved in the plasticity of the visual cortex just as they are involved in the induction of long-term potentiation (LTP), another activity-dependent form of plasticity. The setting up of synaptic connectivity in the neocortex may rely on LTP-like mechanisms. By using immunohistochemistry techniques, we tested the hypothesis of the role of subunit R1 of NMDA (NMDAR1) receptors in the thalamocortical afferent segregation into ocular-dominance columns in the New World monkey, Callithrix jacchus. We employed early and short (2 weeks) monocular-deprivation periods at different ages of postnatal development (17, 46, 67, 107, and 188 postnatal days). We observed heterogeneous distribution of NMDAR1 in the layer IVC receiving the thalamic inputs if the deprivation was realized between the ages of 46 and 107 days. Layers IVCalpha and IVCbeta were involved differently as a function of the deprivation age. The striped pattern lost its differential intensity with the postnatal age. These results are compared with the ocular-dominance pattern evolution described in other works on this primate. They provide evidence of the NMDAR1 role in the modular organization, within time limits, during the postnatal development of the primary visual cortex.