gene of interest is ectopically expressed4,5. Studies using human tissue have been limited, due both to scarce availability of suitable post-mortem or surgical tissues and the highly invasive tissue acquisition procedures. Ever since the discovery of the Yamanaka factors, iPSCs have served as a transformational tool to produce differentiated human cells for a variety of purposes6,7. This novel technology has enabled researchers to consider different strategies for modelling human neuropsychiatric disorders in a culture dish8. However, studies performed on cell populations that are of en composed of mixed neuronal subtypes in a conventional two-dimensional (2D) format cannot recapitulate the complexity of the physiological circuitry in vivo. Three-dimensional (3D) models provide a greater degree of cyto-architecture9,10, but still have not yet provided a compartmentalized context for neurocircuit formation. When the goal is to reproduce a cyto-architecture involving multiple brain regions, in vitro models must compartmentalize different neuronal subtypes, while allowing them to establish functional neuronal connections.
