Mechanics of the Spatiotemporal Evolution of Sulcal Pits in the Folding Brain

Understanding the development of complex brain surface morphologies during the fetal stage is essential for uncovering mechanisms behind brain disorders linked to abnormal cortical folding. However, knowledge of the spatiotemporal evolution of fetal brain landmarks is limited due to the lack of longitudinal data capturing multiple timepoints for individual brains. In this study, we develop and validate a true-scale, image-based mechanical model to explore the spatiotemporal evolution of brain sulcal pits in individual fetal brains. Our model, constructed using magnetic resonance imaging (MRI) scans from the first timepoint of longitudinal data, predicts the brains surface morphology by comparing the distribution of sulcal pits between predicted models and MRI scans from a later timepoint. This dynamic model elucidates how a smooth fetal brain with primary folds evolves to form secondary and tertiary folds. Our results align with imaging data, showing that sulcal pits are stable during brain development and can serve as key markers linking prenatal and postnatal brain characteristics. The model provides a robust platform to study the evolution of sulcal pits in both healthy and disordered brains, which is crucial as altered sulcal pits patterns are seen in disorders such as autism spectrum disorder (ASD), polymicrogyria, down syndrome, and agenesis of the corpus callosum. This research represents a significant advancement in understanding fetal brain development and its connection to disorders that manifest as abnormal sulcal pit patterns later in life.