Fig. 3. Neurodevelopmental patterning principles and region-specific brain organoid culture protocols.

During development, the identity of different brain regions is established by patterning of the neural tube through the action of developmental signaling pathways. Applying the same principles in vitro, the cells in the developing organoid can be guided to adopt fates of specific brain regions by supplementing the culture media with patterning molecules. The schematic drawing represents the different regions of the human neural tube (right) and a transverse section of the telencephalon (left) with the corresponding crucial patterning factors. The boxes include patterning strategies from key studies that pioneered region-specific patterning protocols.