The neuronal composition of the insula in primates displays a gradient, transitioning from
granular neocortex in the posterior-dorsal insula to agranular neocortex in the anterior-
ventral insula with an intermediate zone of dysgranularity. Additionally, apes and humans
exhibit a distinctive subdomain in the agranular insula, the frontoinsular cortex (FI), defined
by the presence of clusters of von Economo neurons (VENs). Studies in humans indicate
that the ventral anterior insula, including agranular insular cortex and FI, is involved in social …