Figure 2

Spontaneous activity observed in whisker-innervating region of neonatal TG. (a) Experimental schematic for performing calcium imaging in a mouse TG ex vivo. See “Methods” for details. (b) A representative raw image frame of ex vivo calcium imaging from a total of 600 frames recorded over a period of 10 min (Image 3). The red circles indicate ten exemplary regions of interest (ROIs) of spontaneously firing neurons. (c) Standard deviation image of all 600 frames recorded as indicated in (b). The red circles indicate the same ROIs labelled in (b). d) Background subtracted (f − fo) images of the red square shown in (b) and (c) at six different timepoints taken at 50 s interval (350th–599th frame). (e) Calcium transients of the ten example ROIs in the 10 min duration. The blue rectangle indicates the range of the timepoints shown in (d) (350th–599th frame). (f) Binary raster plot for the ten example ROIs. Only the calcium transients exceeding the threshold are counted as firing. (Firing threshold: Mean + Std. Dev.). (g) Same image as (b) revealing the ROIs of all the detected spontaneously firing neurons in the 10 min duration. The yellow circles mark individual ROIs. (Total: 73 ROIs). (h) Representative correlation matrix calculated from the fluorescent signals of all the ROI pairs shown in (g) (Firing threshold: Mean + Std Dev). The black squares outline exemplary ROI pairs 23–63 and 49–59, respectively. (i) Fluorescence signals of two example ROI pairs having high correlation (> 0.5). The pair shown above (ROIs 23 and 63) are located far (339.3 µm) from each other and the pair shown below (ROIs 49 and 59) are located close (76.4 µm) to each other (see (g)). Correlation matrix of these exemplary ROIs is shown. (j) The plot compares the Pearson’s correlation coefficients of all ROI pairs with the distance between them. Each circle represents an individual ROI pair. The dashed vertical line separates the non-correlated ROI pairs (correlation coefficient ≤ 0.5) from correlated ones. (N = 4 animals). (k) Violin plot showing the distribution of all the correlated and non-correlated ROI pairs based on their inter-ROI distance. The dashed horizontal line represents the median, and the two dotted lines represent the quartiles. Two-tailed Mann–Whitney test was performed to check for significance (p value < 0.0001) (Total non-correlated ROI pairs = 6547, Total correlated ROI pairs = 129, N = 4 animals).