Amazing stuff!
"There has long been debate over exactly how early in human brain development sex differences first emerge, and what causes them. Previous research has typically studied prenatal or postnatal brain development alone but not both together. That means that until now it has not been possible to study brain growth across the prenatal to postnatal transition.
Researchers ... analysed data that mapped how the human brain develops continuously across the prenatal to postnatal transition. This enabled them to develop a more accurate model of early human brain development and to pinpoint exactly when sex differences in brain growth first emerge. ...
on average, males showed greater increases in brain volumes with age, across the whole brain, compared to females. ...
“The next step is to test if the observed sex differences in human brain growth are driven by prenatal sex steroid hormones, such as testosterone and estrogen. Male fetuses are exposed to much higher levels of these hormones which we know play a role in shaping sex differences in the brain and behaviour in other animals. We need to test if the same is true in humans.”
The research also provided several other important insights into how the brain grows during early development. For example, different brain regions and tissues were found to mature at different rates. White matter – responsible for connecting different brain regions – was found to be the main contributor to brain growth during mid-pregnancy, while grey matter – responsible for cognition and information processing – was found to dominate growth during late pregnancy and after birth.
The researchers also found that early brain development is carefully timed to meet ongoing developmental demands. For instance, subcortical grey matter structures (those deeper within the brain, such as the amygdala, cerebellum, and thalamus) show earlier peak growth rates than cortical grey matter, suggesting that brain systems supporting basic functions mature earlier than those involved in higher-order cognition. ..."
From the abstract:
"The perinatal period, encompassing both prenatal and early postnatal stages, is a highly dynamic and foundational phase of brain development. Despite its significance, limited work has tracked brain growth continuously across prenatal to postnatal development.
In this study, we analysed one of the largest perinatal MRI datasets from the Developing Human Connectome Project (798 scans from 699 unique individuals: 263 prenatal and 535 neonatal; 380 males and 319 females) to model age-related changes and sex differences in brain volumes from 21 to 45 weeks postconceptional age.
We found that total brain volume grew at an increasing rate up until the early postnatal period, with white matter dominating mid-gestational growth and gray matter dominating late-gestational and postnatal growth.
Subcortical gray matter structures showed distinct trajectories and earlier peak growth rates compared to cortical gray matter structures.
Additionally, sex differences in brain growth patterns were observed, with males showing greater volumetric increases with age compared with females. The findings demonstrate the evolving structural dynamics of perinatal brain development as well as the importance of integrating prenatal and postnatal neuroimaging to map continuous early brain growth trajectories."
Fig. 4 Regions showing significant quadratic and cubic sex-by-age interactions. Brain volumes (in mm3) that show significant quadratic or cubic sex-by-age interactions plotted against postconceptional age (in weeks) from 21–45 weeks post-conception. Volumes are plotted according to the trajectory (linear, quadratic, or cubic) determined to be the best fit by model comparisons.
