Figure 4

Neurite size and node type features. a. Example morphologies along with node-type proportions (%C) illustrate how difficult it is to estimate topological patterns by visual inspection of full morphologies [65-67]. b. Percent C distributions of axons (magenta) and dendrites (blue) overlap but are clearly distinct. Inset: Pyramidal cell basal apical dendrites (green) fall between basal dendrites and axons, which respectively are similarly distributed to the (non-apical) dendrites and axons of all (non-pyramidal) neurons. Biased terminal (dark gray) and segmental (light gray) growth bound the neurite populations, with the unbiased distribution of tree shapes (black) falling in between. c. Schematics of terminal (top) and interstitial (bottom) growth starting from a representative seed tree shape with sequence CCT. Colored dots represent potential bifurcation points given the growth mechanism, with their respective resulting branches seen in the trees surrounding the initial tree. Segmentally grown trees contain more C bifurcations than terminally grown trees on average, though the percentages stabilize at lower values (seen in panel b) at around 15 bifurcations. d. Percent C versus sequence length for axons and dendrites compared to the tree shapes baseline, segmentally grown trees, and terminally grown trees with low-order bias. Axons fall in between segmental and terminal growth while the bulk of dendrites display terminal growth followed by a possibly segmental growth-based rise in %C with larger sequence lengths. Below: Distribution of sequence lengths for axons and dendrites. e. Percent C as a function of relative position within sequences for dendrites of several sequence size groups along with segmental and terminal growth. The increase in %C with sequence length is sequence-wide and not specific to distal portions of trees. The initially low %C and rise to stability is similar to that displayed by terminally grown trees.