Extended Data Fig. 8: Modulation of global events in apical dendrites relative to basal dendrites by visual stimuli.

a, Receptive field mapping with sparse noise stimuli and example receptive field. b, Left, schematic with volume imaging planes. Right, example neuron showing ultra-sparse expression. Isolated somata were identified, their receptive fields mapped, and apical dendrites traced. Visual stimuli (same as in Fig. 3) were then positioned relative to the receptive field. c, Traces from different dendritic locations. Arrows highlight events with variable ratio of apical to basal fluorescence. d, Top left, apical dendritic responses to inverse and full field stimuli. Bottom left, basal dendritic responses to same stimuli. Top right, apical dendritic responses to Gabor stimuli. Bottom right, basal dendritic responses to same stimuli. Each trace shows one trial, with fluorescence from all apical and all basal ROIs averaged to get one trace per compartment. e, Same data as in d, averaged across trials (mean ± s.e.m.) with responses to Gabor stimuli in blue and responses to inverse and full field stimuli in red, separately for apical (top) and basal dendrites (bottom). f, Top, distribution of apical-to-basal fluorescence ratios across trials for the two stimulus classes for one cell. Bottom, same data, comparing the real difference between the apical-to-basal fluorescence ratios (difference of means of histograms above) to the shuffling stimulus ID for the same trials. g, Top, apical-to-basal ratio differences for 26 recordings. Significantly modulated neurons shown in dark grey. Dashed line shows mean of all cells. Bottom, for the five significantly positively modulated neurons recorded, the apical-to-basal ratio was computed individually for each apical ROI against the average of all basal ROIs. The correlation between the apical-to-basal ratios across apical ROIs, with correlation of trunk and tuft ROIs in red and the correlation of tuft ROIs in blue.