Fig. 7: Spatial patterns of axonal varicosities distribution at various scales.

A Varicosity types and key features. B Heatmap showing the percentage of varicosities as a function of the distance to the soma. The right panel shows the quartile distribution of varicosities. The distances for each type are normalized independently by the maximal distance among all varicosities for the corresponding type. Labels specify the corresponding brain areas. C Within the dashed line frame: the left side shows representative neurons with somas (black) and varicosities (yellow) connected by a minimum spanning tree (MST). The right-side radar charts illustrating the average of six varicosity features, calculated as mean values after min-max normalized to a 0-100 scale. Right, analogous radar charts for each of the s-types within the analyzed brain areas. D–F Spatial preference of varicosities at various sub-neuronal scales. D Density plots of three morphological features between varicosity branches (red, branches containing varicosities) and null branches (gray, branches without varicosities). The feature “length” refers to the path length of a branch, while “curviness” represents the curviness of the branch. The colored numbers are the mean values of the corresponding categories. E Top, schematic drawing of three bifurcation types defined according to the presence of varicosities in the two child branches. The parent and child branches are topologically connected, with the parent branches being closer to the soma. Bottom, bar plot of the proportions of the three types of bifurcations in each analyzed brain area. F Top, schematic drawing of the length quartiles of a varicosity branch. Bottom, line plot of the ratio of varicosities distributed at quartiles of a varicosity branch. The horizontal dashed line represents the expected distribution if varicosities were uniformly spaced. Source data are provided as a Source Data file.