Figure 6.

Decreased Counts of Specific Neuronal Populations in the Frontal Cortex upon Aging

(A) An image of one NeuN-stained FCTX section, with re-defined tiles demonstrated by black rectangles (file size = 37.4 GB).

(B) (i) Enlargement of a single tile of 10,000 × 10,000 pixels (size = 225 MB). (ii) Enlargement of a 2,500 × 2,500 pixel section. (iii) Three cells as observed in the red channel (top, shown in light blue) and blue channel (middle), and intersection of the two channels (bottom) differentiates between neuronal cells (stained by NeuN in brown on the original slides) and other cells (stained by Heamotoxylin in blue in the middle plot). (iv) The x axis represents the color frequency distribution of the red and blue channels across an intensity range of 256 gray levels, while the y axis represents the frequency of pixel intensity in the image tile depicted in (iii).

(C) Examples of detected neurons that contain small, medium, medium to large (E), or large cell body (F) with size given in pixels. Underneath each image is the histogram 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). The histogram shows the null distribution of t values, calculated using two-tailed Student’s t test over slide counts using 100,000 random permutations from the entire population of the six samples (black bars), while the mean of the true-label t statistics is depicted with a red bar. The right graph shows the cell counts in samples from old (red) and young (blue) groups, with significance calculated with t statistics based on 10,000 random permutations. The star marks bars with a p value < 0.05, and the mean t statistics, p value, and SD of the permutation test are reported on top of the graphs.