(A) Experimental strategy and timeline for histology. Tam = tamoxifen. (B) Quantification and (E) example images of ASPA+ mature oligodendrocytes in the visual cortex at P28 and P60 in CreER− (CTL) and CreER+ (cKO) mice. (C) Quantification and (F) example images of PDGFRα+ OPCs in visual cortex. (D) Example images of myelin in visual cortex. (G) Experimental strategy and timeline for intrinsic signal imaging (ISI). MD = monocular deprivation. (H) Example images from ISI. MD 4/8d = after 4 or 8 days of monocular deprivation. (I) Amplitude of ISI responses and (L) ocular dominance in binocular visual cortex at baseline. Contra = ISI response to contralateral eye stimulation, ipsi = ISI response to ipsilateral eye stimulation. ODI = ocular dominance index, defined as (contra – ipsi ISI responses) / (contra + ipsi). (J) Change in binocular visual cortex ISI responses in adult control mice following four (MD4) or eight (MD8) days of MD. (K) Change in ISI responses in adult cKO mice. (M) Change in contralateral visual cortex ISI responses following MD and recovery (Rec). (N) Change in ipsilateral visual cortex ISI responses. Statistical details in Table S1. **p<0.01, ***p<0.001, ****p<0.0001, ns = not significant.