Fig. 3: Spatiotemporal analysis of PC dendritic voltage responses distinguishes synaptically-driven and regenerative Ca2+ events.
From: All-optical voltage interrogation for probing synaptic plasticity in vivo
a Multiple PC dendrites are often recorded in the same FOV (top), revealing correlated CF activity (bottom) in the fluorescent traces (brown). b Cross-correlogram between PCs 2 and 3 shown in (a), overlaid with a Gaussian fit (green) indicating PC2 and PC3 are from the same microzone. Inset: cross-correlogram between PCs 1 and 3 showing no correlation, indicating they are from different microzones. c The magnitude of average optically evoked IPSP amplitude is plotted for all pairs of PCs (i,j) in the same FOV, showing highly correlated IPSP amplitudes between neighboring PCs (R = 0.807, p = 1.90 × 10−10 (fitted by linear regression and tested via a two-sided Wald test); n = 23 FOVs across four mice), which lies in the 99th percentile of correlation coefficients compared with a within-mouse shuffle (shaded area represents 95% confidence interval). d Each dendrite is segmented into ~5 µm sections (top), which reveals variations in responses across the dendrite (bottom, average of n = 380 spikes blue, gray ± 1 std). e Features are extracted from the fluorescence traces on a trial-by-trial basis. f The normalized response of these features is then compared across the length of the dendrite (left), and the coefficient of variation (CV) is calculated for each feature of each cell (right). g The CV is compared for spontaneous complex spike (CS) and sensory-evoked CS (left). On average, spontaneous CS have a moderate, yet significantly larger CV than evoked responses, showing that the evoked responses have more uniform amplitudes (one-sided Wilcoxon signed-rank test, p = 0.037; n = 40 cells across four mice). h The CV is compared for optically evoked IPSPs and spontaneous CS. On average, IPSPs have a significantly larger CV, meaning IPSP responses are more localized than regenerative CS events (one-sided Wilcoxon signed-rank test, p = 8.14 × 10−3; n = 40 cells across four mice). Red point marks the PC shown in (f).
