Removal of two, but not one, primary basal dendrites shifts orientation preference. a Z-stacked top view of an example ablated neuron and a neighboring control neuron before (left) and after (right) a single primary basal dendrite ablation. Ablated dendrite is marked with dark-red arrow. b Three examples of peak-normalized orientation-tuning curves before (black) and 5 days after one-basal-dendrite ablation (dark-red). c, d Figures in the same format with a-b for two-basal-dendrite ablation (marked with pink). Error bars are standard error of mean across trials. e Histogram of the absolute-value change in preferred orientation (deg) for control (black, n = 35), one-basal-ablation (dark-red, n = 13), and two-basal-ablation (pink, n = 17) neurons. f–h Mean changes in (f) preferred orientation (absolute-value change, ANOVA: F(2, 62) = 6.29, p = 0.003, Kruskal–Wallis: χ2(2,62) = 7.03, p = 0.029), g tuning width (ANOVA: F(2, 62) = 1.71, p = 0.19, Kruskal–Wallis: χ2(2, 62) = 1.44, p = 0.49), and h orientation selectivity index (OSI, ANOVA: F(2, 62) = 1.03, p = 0.36, Kruskal–Wallis: χ2(2, 62) = 0.59, p = 0.75) from von-Mises fitted tuning curves of each neuron 5 days after ablation. See Supplementary Fig. 8 for a histogram of the distribution of changes in tuning width and OSI. Error bars are standard error of mean. For (f), numbers in white indicate n-number of each condition. **p = 0.003 (control vs two-basal), *p = 0.04 (one-basal vs two-basal), ANOVA with Tukey correction. Scale bars for (b) and (d) are 10 µm.