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. 2020 Jun 10;40(24):4622–4643. doi: 10.1523/JNEUROSCI.2339-19.2020

Figure 7.

Figure 7.

Microglial cell/neuron ratio varies uniformly with neuronal density but not with structure mass across brain structures and mammalian species. Microglial cell/neuron ratio is plotted as a function of the brain structure mass (A), neuronal density (B), or non-neuronal cell/neuron ratio (C). A, p values for Spearman correlations when all structures are analyzed together, except for Primata, Cx only, fall below p < 0.01 for all clades together and individually, except for Carnivora (p = 0.0483; not significant), Primata (p = 0.3851), and Artiodactyla (p = 0.2453). Spearman p values when Cb is analyzed individually are nonsignificant, except when all clades are analyzed together (p = 0.0006). Spearman p values when Cx is analyzed individually are nonsignificant, except when all clades are analyzed together (p = 0. 0015) and for Afrotheria (p < 0.0001). Spearman p values when RoB is analyzed individually are nonsignificant, except when all clades are analyzed together (p < 0.0001). B, p values for Spearman correlations when all structures are analyzed together, except for Primata, Cx only, fall below p < 0.01 for all clades together and individually, except for Primata (p = 0.1600) and Artiodactyla (p = 0.0016). The power function plotted in B has an exponent of −0.973 ± 0.029 (p < 0.0001; r2 = 0.936) and applies to all mammalian species and brain structures. Exponents and p values for each clade individually are listed in Table 5. C, p values for Spearman correlations when all structures are analyzed together, except for Primata, Cx only, fall all below 0.01, except for Primata (p = 0.4198). The power function plotted in C has an exponent of 1.020 ± 0.031 (p < 0.0001; r2 = 0.932) and applies to all brain structures and mammalian species. All clades have a significant relationship, except Primata (p = 0.2252). Each data point represents the values found per brain structure examined for each species colored by clade as in the key. Filled circles represent the Cx, including the hippocampus. Squares represent the Cb. Triangles represent the RoB. B, C, Values are exponent ± SE.