We demonstrate the generation of a human 3D microphysiological system that includes functionally-integrated glutamatergic and GABAergic neurons. This platform has several advantages in comparison to previous adherent or 3D methods9,10,16,35–38. First, it involves the directed differentiation of subdomains of the forebrain that functionally interact in development. In contrast to whole-brain organoids and organoids resembling broader brain regions35,38, this approach allows for modularity by combining separately patterned spheroids into multi-region neural 3D cultures. Second, this system captures in vitro more elaborate developmental processes, including the saltatory migration of interneurons towards the cerebral cortex. Using live imaging of the human forebrain, we demonstrate that this migration is accurately recapitulated with our assembled 3D platform. Third, by enabling their migration into an active neural network, interneurons integrate into a synaptically-connected microphysiological system without the requirement of seeding onto rodent cortical cultures or brain slices. Assembling networks using this modular system may facilitate the study of excitation to inhibition interplay during cortical development.
