Fig. 5.

Determination of the average GCaMP6f-mediated ΔF/F response produced by a single activated PF in order to calculate the areal density of functional PFs. (A) (Left) Transmitted light image of a superfused sagittal cerebellar slice showing the position of a stimulation electrode in the granular layer relative to the field of view in the molecular layer for which the ΔF/F image following stimulation in the granular layer is displayed (Right). In the presence of 50 µM 4AP to enhance the ΔF/F responses (see SI Appendix, data). (B) Zoom of the part of the ML delimited by a dotted square in A, Right, with a ΔF/F scale enabling unambiguous detection of spot-like ΔF/F responses (not present in the absence of stimulation: Right). (C) Thresholding for identification of spot-like ΔF/F responses (6 responses on this image). Their peak values (${\mathrm{\Phi }}_{1PF, in 4AP}$) were determined as detailed in SI Appendix, Fig. S7. (D) Distribution of ${\mathrm{\Phi }}_{1PF, in 4AP}$ for data from Y and A mice (data from individual groups, with spot-like ΔF/F responses attributed to U or L loci according to their distance from the PC soma closest to the stimulating electrode, are shown in Table 1). (E) Average $\overline{\mathrm{\Sigma }{\mathrm{\Phi }}_{1PF}}$ values calculated from ${\mathrm{\Phi }}_{1PF, in 4AP}$ values (see SI Appendix, Supplementary Information Text) for the four groups of data. (F) Average $\alpha ·d_{PF}$ (areal density of functional PFs) calculated from $\overline{\mathrm{\Sigma }{\mathrm{\Phi }}_{1PF}}$ and ${\mathrm{\Phi }}_{\mathit{max}}$ according to Eq. 5. Calculations with error propagation.