Extended Data Fig. 5: Spatial scale of local events in apical tuft dendrites.

a, Two separate ROIs were drawn over each dendritic segment where events were identified. One “mask” ROI encapsulated the entire branch with its spines, and the other “line” ROI traced a single pixel wide line along the branch itself. b, Fluorescence measured in each pixel in the mask ROI was averaged into the nearest pixel of the line ROI, along with all other mask ROI pixels for which that line ROI pixel was the nearest. The geodesic distance between each line ROI pixel and the most proximal line ROI pixel was measured. c, Fluorescence over time and geodesic distance along an example dendrite. The mean fluorescence in each resulting geodesic distance pixel was smoothed with a 4 s moving average and then converted to (F-F₀)/F₀, where F₀ was assigned as the 10^th percentile of the fluorescence in a running window 45 s wide. We then normalized this ΔF/F by the standard deviation of the whole trace to facilitate comparisons across experiments. d, The spatial profile of fluorescence over geodesic distance averaged over the frames identified with red band in c. e, As in c for another example neuron. f, As in d for another example neuron. g, The spatial profile of all identified events, aligned by their peak location and normalized to that value in grey, their average in blue. h, Same data as in g, average ± s.d. i, Average spatial profile is well fit by a 3-term Gaussian with full-width at half-maximum of 11.2 μm.