Figure 5.

Decreased Counts of Oligodendrocytes in the Frontal Cortex upon Aging

Six FCTX brain sections were stained and imaged (from three old and three young post-mortem brain samples). Each sample contains thousands of equal-size slides each 1,600 × 1,200 pixels, as captured by a Zeiss AxioScan slide scanner following staining with the Olig2 antibody.

(A) An example of a BA9-Olig2 slide shown in a full-resolution pyramid, with gradual zooming into two typical cells: one stained brown (OLG cells) and one stained blue (other cells).

(B) General computational pipeline for the analysis of high-resolution immunohistochemical high-dimensional imaging data allowed us to quantify both OLG and other cells in each FCTX slide.

(C) Comparison of OLG counts that asks if the number of cells of interest is different in young samples compared to old (i.e., red bar shifted to the right means increased count in young samples). In each panel, the histogram represents the null distribution of t values calculated using two-tailed Student’s t test over slide cell counts randomly sampled from the entire population of the six samples, using 100 random iterations over 500 permutations where the true-label t statistics is depicted with a red bar, and the remaining distribution was calculated based on shuffled labels. The analysis was done on overall 8,766 young and 10,922 old group slides (left). From a total of 2,612 young and 1,828 old group high-density slides, the 50 slides with the highest density were selected per case for quantification. Similarly, from 1,154 young and 1,277 old group low-density slides, the 50 slides with the lowest density were chosen per sample for quantification.

(D) Cell counts in samples from old (red) and young (blue) groups, with significance calculated with t statistics as described in (C). The star marks bars with a p value < 0.05 and the mean T statistic, p value and SD of the permutation test are reported on top of the graphs.