Fig. 6: Spatial distribution of optotagged units.

a, Estimated location of units relative to the driving emitter for units that were optotagged by red light (red dots; n = 83 units from 25 sessions) and blue light (blue dots; n = 178 units from 26 sessions). b, Same as a, but for units from the same sessions that were not optotagged (black dots; n = 500 randomly selected units from 40 sessions). For these untagged units, the driving emitter is selected arbitrarily. c, Probability of tagging a unit as a function of distance from the driving emitter along the shank insertion axis. Most tagged units are located below the driving emitter (deeper in the brain). **P < 1 × 10⁻¹⁰ (Wilcoxon two-sided signed-rank test for difference from zero). d–f, Same data as a–c, but plotted relative to the nearest emitter (rather than the driving emitter), showing the probability of being optotagged at any location within 50 μm of an emitter. Bottom: histograms in d,e show the distributions of unit locations orthogonal to the shank insertion axis. *P < 0.01; not significant (NS), P > 0.05 (Kolmogorov–Smirnov test for equality of distributions). Information about cell types and opsins in these experiments is provided in Supplementary Table 1.