Females exhibit smaller volumes of brain activation and lower inter-subject variability during motor tasks

Past work has shown that there are both structural and functional differences in the brains of females versus males (Ritchie et al., 2018). Specifically, males have larger cortical and sub-cortical volume and surface area (both total and subregional), while females have greater cortical thickness in most brain regions. Given these differences it is possible that males may show larger volumes of brain activation and greater variability in patterns of brain activity. Yet to date little work has systematically considered whether patterns of brain activity indexed with functional MRI differ between females and males. The current study sought to remediate this issue by employing brain somatotopic motor mapping from a previously published (Ma et al., 2022) and openly available dataset to test differences in patterns of functional brain activity associated with 12 voluntary movement patterns in females versus males. We discovered that females exhibited smaller volumes of brain activation across all 12 movement tasks, and lower patterns of variability between female participants in 10 of the 12 movements. We also observed that in these data females had greater cortical thickness which is in alignment with previous structural sex difference analyses (Ritchie et al., 2018; Wierenga et al., 2022). Overall, these findings provide a basis for considering sex differences in future fMRI research and provide a foundation of understanding for which various neurological pathologies may present different between females and males. ### Competing Interest Statement The authors have declared no competing interest.