Extended Data Fig. 6: Relationship between dendrite and long-range axonal projection for IT neurons.
(a) The distributions of axon projection strength to major targets of IT dendrite subtypes with their soma distributions in PFC subregions. Top, hierarchical tree of IT dendrite subtypes based on their soma distribution (Euclidean distance, Ward’s linkage). Middle, dot plot shows the number of neurons (represented by dot size) in PFC subregions. Bottom, violin plot shows the axon projection strength. Colored by dendrite subtypes. (b) Pearson’s correlation between dendrite morphological features and axon projection bias to striatum (STR) or not to STR of L5 IT neurons in ACA/PL. (c) Representative retrosplenial (RSP) area-projecting and STR-projecting IT neurons in PL/ACA regions with distinct dendritic morphology. (d) Soma distributions of the neurons in different L5 IT dendrite subtypes and the gradient of their dendrite morphology/axon projection pattern. Left, soma distributions of L5 IT neurons on the PFC flatmap with dendrite subtypes color-coded. The shaded area denotes the ACA/PL. Middle and right, correlations of the length of basal dendrite between soma position in anterior-posterior axis of ACA/PL or axon projection pattern projecting to STR or not for the L5 IT dendrite subtypes (linear regression, P value and R2 are shown). Shaded areas around the regression line indicate 95% confidence intervals. P values were calculated via two-sided t-test. (e) Axon subtype 21 and 38 are intermixed in the t-SNE plot based on dendrite morphology dissimilarity (top) but are separated in the t-SNE plot based on the dissimilarity of their axon projections (bottom). (f) Representative IT neurons in PL/ACA regions with similar dendritic morphology but distinct axon projection patterns, color-coded by axon subtypes. Red, axon subtype 38 with only ipsilateral caudate putamen (CP) projection. Blue, axon subtype 21 with both ipsilateral and contralateral CP projection. Top, dendrite morphology. Bottom right, axon projection pattern. Bottom left, violin plots show the indistinguishable dendrite morphology of axon subtype 21 and 38 (P values are shown, two-sided Wilcoxon rank sum test). Top right, (g) Representative L4-like spiny stellate neuron and a nearby pyramidal neuron with similar axon projection pattern.
