Table 2.

Correlation between local GI and other parameters along the AP axis.

Spearman correlation coefficients for GI and each of the parameters indicated. Correlations exclude the prefrontal, temporal, and occipital poles. ns, not significant at the p < 0.05 level. a, average fiber caliber in the white matter; n, estimated fraction of gray matter neurons connected through the white matter; n.a, product that, multiplied by N_G, defines A_W according to our model (Mota and Herculano-Houzel, 2012); n.N, estimate proportional to the total number of fibers in the white matter that are connected to the gray matter; n.N.a, estimate of the surface area of the gray/white matter interface, A_W; n.N.a/A_E, estimate of the degree of folding of the gray/white matter interface.