Experience-dependent regulation of NMDAR composition is reversible. (Left) Brief light exposure (2 hr) of DR animals induced a significant increase in NR2A protein that could be reversed by 72 to 96 hr of subsequent visual deprivation [one-way ANOVA, F (3, 18) = 13.14, P = 0.0004. Asterisks (*) denote significant difference vs. dark-reared controls in Student–Newman–Keuls posthoc comparison, P < 0.05)]. (Right) Placing LR animals in the dark for 72 to 96 hr, but not 24 hr, induced a decrease in the level of NR2A protein [one-way ANOVA, F (3, 24) = 6.49, P = 0.0023; asterisks (*) denote significant difference vs. light-reared controls in Student–Newman–Keuls posthoc comparison, P < 0.05)].