Figure 4. CCKBCs and PVBCs similarly innervate the soma-dendritic membrane surface of PNs.
(A and B) Neurolucida reconstruction of the postsynaptic PN (same as in Figure 3) and its dendrogram analysis showing the contact sites on the perisomatic region (open magenta dots) and on the dendritic branches (filled magenta dots). Bottom on B: schematic visualization of the innervation pattern compressed along a single horizontal line. Somatic boutons shown in the yellow area, contacts on the perisomatic region are labeled with open dots and dendritic boutons with filled dots along the line indicating their distance from the soma. (C and D) Schematic innervation pattern of the reconstructed 38 CCKBC-PN and 26 PVBC-PN pairs. Bottom: Spatial distribution of the contacts, data from all pairs pooled together. (E) Comparison of the cumulative distribution of the contacts on PNs from the two BC types show no difference in the innervation patterns (p=0.29, K-S test). (F) BCs innervate the whole length of PN dendrites, however, the density of the contacts decreases exponentially towards the end of the dendrites (CCKBCs: r = 0.884, tau: 71.4 ± 8.2 µm; PVBCs: r = 0.557, tau: 79.7 ± 23.4 µm). Boutons contacting the cell bodies were excluded from this analysis. (G–J) Comparison of the total number of boutons (CCKBC: 7.92 ± 0.80, PVBC: 10.73 ± 1.16, p=0.065), the average bouton distance (CCKBC: 59.20 ± 4.80 µm, PVBC: 68.39 ± 5.97, p=0.38), the number of perisomatic boutons (CCKBC: 2.68 ± 0.41, PVBC: 3.53 ± 0.67, p=0.44) and ratio of perisomatic boutons (CCKBC: 0.33 ± 0.04, PVBC: 0.33 ± 0.05, p=0.83) of CCKBC-PN and PVBC-PN connections showed no significant difference (all M-W test, n = 38 CCKBC-PN pairs and n = 26 PVBC-PN pairs). Scale in A: 50 µm.