IOS responses expand into deprived barrel columns. Estimation of the expansion of spared whisker representations into deprived barrel columns. A, B, Schematic illustrating the transformation of individual IOS response areas into a common coordinate system. The max response of whiskers C1 ([x_c1,y_c1], dark blue) and C2 ([x_c2,y_c2], light blue) were used to calculate the angle θ between them (A, B₁). The IOS response areas were rotated by this angle (B₂) using the equations x′ and y′ shown in the inset. Subsequently the response areas were translated to the origin by subtracting their max responses (x″ and y″). The position of the D and E row (deprived) barrels was now constant for all whiskers and animals (B₃). C, D, To visualize the extent of whisker response expansions over time, we plotted histograms displaying the spatial response probability distribution for the C1 and C2 whiskers at the start (A_start) and the end of the experiment (A_end). Pixels that were present in all responses have a probability of 1.0. At the start, the probability distribution of IOS responses was similar between control and lesioned animals (C, D, left panels). At the end of the experiment, this probability distribution was different (D, right panel). E, Statistical comparison of the response area expansion in control and lesioned animals at the start (left panel) and the end (right panel) of the experiment. We used a set of thresholds along the ordinate axis to quantify the expansions toward the deprived cortex for each whisker. At the start of the experiment both groups showed similar areas crossing each of the thresholds. After FR animals displayed significantly larger average areas beyond the thresholds compared with controls. **p < 0.01 Mann–Whitney.