Driving tissues into shape: controlling patterning and morphogenesis in the early human brain

Development is a multiscale process which couples cell fate transitions and tissue architecture to drive organogenesis. The absence of predictive frameworks linking cell fate to morphogenesis impedes the creation of physiologically relevant tissues in vitro and presents opportunities to uncover the physics of emergent organization. Minimal control parameters for embryonic development remain poorly understood. At cellular scales, transcription, signaling, migration, proliferation, and differentiation shape architecture; in the brain, these processes set cell type ratios, drive neocortical expansion, and sculpt macroscopic morphology.  Yet progress in studying human brain development is limited by evolutionary differences between model organisms and humans. Consequently, the lineage decisions leading the differentiated cell types of the neocortex, neurons and glia, and the symmetry breaking event(s) driving their emergence and subsequent patterning remain unknown. Here, we reveal a novel developmental pathway specifying the bifurcation of glial and neural progenitors and we show that mechanical signals underlie this early cell fate patterning event in the brain. Our findings are of fundamental interest to biologists and physicists.