(A) RGPs (radial glial progenitors) at the ventricular surface of the MGE (medial ganglionic eminence) and PoA (preoptic area) undergo asymmetric divisions (A.D.) to self-renew and simultaneously generate a post-mitotic IN (interneuron) or an IPC (intermediate progenitor cell), which can further undergo symmetric divisions (S.D.) in the subventricular zone to produce differentiating interneurons. In the mature cortex, clonally-related interneurons do not randomly disperse, but are frequently organized in spatially isolated intra- or inter-laminar clusters. Adapted from Sultan, K.T. et al., 2013 and 2014.153, 154
LGE, lateral ganglionic eminence; Ctx, cortex.
(B) Clonally-labeled interneurons in clusters (green) preferentially form electrical, but not chemical, synapses with each other compared to nearby, non-clonally related interneurons (red). This lineage-related preferential electrical coupling promotes the coordinated formation of inhibitory synapses between clonally-labeled interneurons and the same nearby excitatory cells in the cortex.