Sex differences in intrinsic functional cortical organization reflect differences in network topology rather than cortical morphometry

Abstract

Brain size robustly differs between sexes. However, the consequences of this anatomical dimorphism on sex differences in intrinsic brain function remain unclear. We investigated the extent to which sex differences in intrinsic cortical functional organization may be explained by differences in cortical morphometry, namely brain size, microstructure, and the geodesic distances of connectivity profiles. For this, we computed a low dimensional representation of functional cortical organization, the sensory-association axis, and identified widespread sex differences. Contrary to our expectations, observed sex differences in functional organization were not fundamentally associated with differences in brain size, microstructural organization, or geodesic distances, despite these morphometric properties beingper seassociated with functional organization and differing between sexes. Instead, functional sex differences in the sensory-association axis were associated with differences in functional connectivity profiles and network topology. Collectively, our findings suggest that sex differences in functional cortical organization extend beyond sex differences in cortical morphometry.TeaserInvestigating sex differences in functional cortical organization and their association to differences in cortical morphometry.

Microstructural asymmetry in the human cortex

“…Looking ahead, the implementation of a normative model could elucidate the developmental trajectory of microstructural asymmetry across the lifespan, facilitating the identification of individual trajectories (Bethlehem et al, 2022). Previous work has also reported marked sex-differences in various indices of cortical structure (DeCasien et al, 2022; Küchenhoff et al, 2023; Liu et al, 2020; Serio et al, 2023), possibly related to differential sex hormonal expression and physiological markers (Wisniewski, 1998). Indeed, in the current work we observed an overall stronger asymmetry in males relative to females.…”