Representative examples of optically recorded activity and polar maps in V1 of both vehicle-treated mice (control, A, C) and animals treated with the MMP-inhibitor GM6001 (GM6001, B, D), before (no MD, A, B) and after monocular deprivation (7 days MD, C, D). V1-maps after visual stimulation of the contra- (contra) and ipsilateral (ipsi) eye in the binocular region of V1. Top panels (A–D) display grayscale-coded response magnitude maps (V1-activation) and their quantification on the right: histogram of (C-I)/(C+I). V1-activation is illustrated as fractional change in reflection ×10-4. Average V1-activation is illustrated as a number at the lower right corner of each magnitude map; the average OD-index (ODI) as a number in the upper right corner of the histograms. Bottom panels represent color-coded polar maps of retinotopy, and the color-coded OD-map. In both control and GM6001-treated mice without MD, V1-activity was dominated by input from the contralateral eye: activity patches after contralateral eye stimulation were darker than after ipsilateral eye stimulation, the average ODI was positive, and warm colors prevailed in the OD-map, illustrating contralateral dominance. After 7 days of MD, OD-plasticity occurred only in control (C) but not in GM6001-treated mice (D): in control mice, both eyes activated V1 rather equally strong, the OD-histogram was shifted to the left (blue arrow in C), and colder colors appeared in the OD-map. In contrast, in GM6001-treated mice, the deprived (contralateral) eye continued to dominate V1, the ODI was not reduced and warm colors still dominated the OD-map. Scale bar: 1mm.