Unlocking human brain networks by assembling circuits in vitro and in vivo.

In this issue of Cell Stem Cell, Wang et al.1 generate human nucleus basalis of Meynert organoids (hnbMOs), establish a human-specific cholinergic projection system in transplanted assembloids, and identify projection deficits in Down syndrome-derived assembloids. This study provides a valuable model for investigating nbM-related neural circuits and neurological disorders.