Translational Neuroimaging and Genomics of Sex Differences in Brain Development

Humans display robust age-dependent sex differences in diverse domains of motor, language and social development, as well as in risk for developmentally-emergent disorders. There is a robust male-bias in risk for early-emerging impairments of attention, motor control, language and social functioning, vs. a female-bias for adolescent-emergent disorders of mood and eating behaviors.  The stereotyped pattern of these sex biases suggests a role for sex differences in brain development, and further implies that these differences unfold in a spatiotemporally-specific manner. In support of this notion - in vivo structural neuroimaging studies find focal sex differences in brain anatomy that vary over development. However, the mechanisms driving these neurodevelopmental differences remain poorly understood in humans. In particular, we do not know how specific spatial and temporal instances of sex-biased brain development in humans relate to the two foundational biological differences between males and females: gonadal sex-steroid profile (henceforth “gonadal”) and X/Y-chromosome count [henceforth “sex chromosome dosage” (SCD)]. In our prior cross-sectional neuroimaging studies, we have however provided extensive evidence that gonads and SCD can both shape regional anatomy of the human brain, and that similar effects can be observed in mice. However, to date there are no available data on the temporal unfolding of gonadal and SCD effects on regional brain anatomy, and no quantitative frameworks for comparing these effects between observational humans studies and experimental work in mice.

This project will build on a longstanding productive collaboration between Drs. Lerch and Raznahan, with rich existing datasets, to better-specify sex as a neurobiological variable in health and disease. Key questions for the project relate to (i) fine-grained spatiotemporal mapping of sex, SCD and gonadal effects using neuroimaging in transgenic mice and rare patient groups, (ii) computational solutions for comparison of these maps between species, and (iii) “decoding” of imaging data using measures of gene expression in brain tissue and integrative functional genomics. The resulting anatomical, and genomic signatures for sex-biased development will be probed for association with biological bases of sex-biased brain disorders.

*This project is available for the 2021 Oxford-NIH Pilot Programme*