Symposium
Although patterns of functional connectivity are considered to be largely stable, trait-like features of the human brain, they also exhibit a remarkable variability, both within and between individuals. This talk will present multimodal and interdisciplinary research exploring variability and sex differences in functional brain organization across population-level and individual scales, revealing both shared and sex-specific effects. First, in a large sample (N = 1000) from the Human Connectome Project, we investigated sex differences in functional cortical organization using the sensory-association (S-A) axis, a low-dimensional representation of functional brain organization. Our findings demonstrated widespread sex differences in the S-A axis that were not systematically explained by cortical morphometry (i.e., brain size, microstructural organization, nor the mean geodesic distance of functional connectivity profiles). Instead, these effects reflected sex-specific variations in network topology and functional connectivity profiles, suggesting that sex differences in functional cortical organization extend beyond sex differences in cortical morphometry. Second, at the individual level, data from two densely sampled individuals (one female, one male) revealed dynamic intra-individual variability in the S-A axis over 20–30 consecutive days of testing. Daily variability was greatest in temporal limbic and ventral prefrontal regions in both participants, but was more strongly pronounced in the male subject. Beyond shared patterns of effects, the female and male participants further revealed subtle and unique associations between neuroendocrine fluctuations and intra-individual variability along the S-A axis. These findings point to neuroendocrine factors as possible modulators of intra-individual variability in functional brain organization. Together, these studies bridge population- and individual-level perspectives, uncovering both similarities and differences in macroscale functional brain organization across sexes and exploring their interdisciplinary underpinnings. This talk underscores the importance of considering sex differences when studying functional brain organization, as well as examining variability across scales to study both group-level generalizable effects and individual-specific mechanisms, for a better understanding of functional variability in health and disease.
Relevant recent publications:
- Serio, B., Hettwer, M. D., Wiersch, L., Bignardi, G., Sacher, J., Weis, S., ... & Valk, S. L. (2024). Sex differences in functional cortical organization reflect differences in network topology rather than cortical morphometry. Nature Communications, 15(1), 7714.
- Serio, B., Yilmaz, D., Pritschet, L., Grotzinger, H., Jacobs, E. G., Eickhoff, S. B., & Valk, S. L. (2024). Exploring sex-specific neuroendocrine influences on the sensorimotor-association axis in single individuals. bioRxiv, 2024-05.