CA3 and dementia: We found that the dementia-associated patches contain substantially more oligodendrocytes (1.63x enrichment, P<1e-4 by donor-level permutation test) and fewer L6 IT Car3 neurons (0.15x depletion, P<1e-4 by donor-level permutation test) than the other layer 6 patches (Fig. 4D and Supplementary Table 3).