Developmental trajectory of the prefrontal operculum and the consequences of premature birth

Comparative and paleo-neurological evidence suggests that the prefrontal operculum (PFO) plays a pivotal role in the emergence of speech abilities in the genus Homo. Using a new release of the developing Human Connectome Project, we examine cortical development in in utero fetuses (21-36 gestational weeks, gw), preterm (26-36 gw) and full-term neonates (37-44 gw). Guided by Evo-Devo principles, we hypothesize that brain regions that evolved most recently (such as the PFO) should also mature latest during ontogeny and be especially vulnerable to premature birth. Our study provides a fine-grained timeline of macroscale sulcal organization and shows that the PFO emerges only at the very end of gestation (41 gw). Prematurity is associated with a one-week delay in global sulcal formation but, paradoxically, with acceleration of PFO emergence by approximately three weeks. These findings refine the normative timeline of cortical folding and offer a framework for identifying atypical PFO organization and potential links with developmental speech-related deficits.