Figure 8. Comparison of the innervation patterns of CCKBCs and PVBCs at single-cell and population levels.

(A) Kv2.1 immunostaining (blue) was used to label the perisomatic region of cells in slices where BC-PN pairs were visualized (biocytin in BC (magenta), and Alexa 488 in PN (green)). Contact sites from the same BC were identified on the intracellularly-labeled PN (green arrows) and on Kv2.1-expressing profiles (white arrows), enabling the investigation of the innervation pattern at both single-cell and population levels. (B) Analysis of the bouton distribution of a representative biocytin-labeled BC (shown in panel A) on 17 Kv2.1-labeled PNs. Data are arranged based on the number of biocytin-filled boutons contacting their perisomatic region (circles). For comparison, the number of the contacts formed on the intracellularly labeled postsynaptic PN is shown with a red triangle. (C and D) Summary data of the innervation patterns of 21 BCs showing that the number of the established contacts at the single-cell level (on the biocytin-filled postsynaptic PN) is independent of the average number of the contacts determined at population levels (i.e., on multiple Kv2.1-labeled PNs). (D) Data in C is arranged as a function of increasing contact number obtained in the pairs. (E) Target distribution analysis of CCKBCs and PVBCs at the population level obtained with Kv2.1 staining: ratio of contacts on the soma, proximal dendrites belonging to the perisomatic region and distal dendrites. Average perisomatic target ratio is shown with red dots. Data is arranged as a function of increasing ratio of contacts on the perisomatic region. Scale: 10 µm. For additional analysis see Figure 8—figure supplement 1.

DOI: http://dx.doi.org/10.7554/eLife.20721.017

Figure 8—figure supplement 1. Possible innervation pattern strategies for PVBCs and CCKBCs.

(A) The ratio of perisomatic contacts at single-cell and population levels shows no correlation. (B) Schematics of two different possible innervation pattern strategies. In pattern A, BCs with high perisomatic target ratio (PTR) innervate more PNs than those BCs having low PTR. In pattern B, BCs with high PTR innervate the same amount of PNs than BCs with low PTR, but with more contacts on the perisomatic region. This implies a higher inhibitory efficacy on those PNs. (C) The hypothetical correlation between the number of the perisomatic contacts and average perisomatic target ratio in pattern A (red) and B (purple). (D) Correlation between the number of the perisomatic contacts and average perisomatic target ratio in the experimental dataset. This plot suggests that BCs in the BA might follow innervation pattern ‘B’, implying that those BCs which target the perisomatic region with high ratio at the population level, tend to form more contacts on the perisomatic region of individual PNs, therefore having a more powerful controlling effect on the postsynaptic neuron activity.

DOI: http://dx.doi.org/10.7554/eLife.20721.018