The term area PGs refers to a cortical structure located in the posterior half of inferior parietal cortex, a region that is much expanded in humans relative to macaques and chimpanzees. It is bounded rostrally by area PFm, caudally by area PGp, dorsally by area IP1, and ventrally by area PGi. Defined by multiple criteria, it is a major node in the default network. Other authors have referred to the same topological area as PGa, 39, PG, or 90 ( Glasser-2016 ).