and control subtype and laminar identity of MGE-derived neocortical interneurons.

Distinct cortical interneuron (CIN) subtypes have unique circuit functions; dysfunction in specific subtypes is implicated in neuropsychiatric disorders. Somatostatin- and parvalbumin-expressing (SST and PV) interneurons are the two major subtypes generated by medial ganglionic eminence (MGE) progenitors. Spatial and temporal mechanisms governing their cell-fate specification and differential integration into cortical layers are largely unknown. We provide evidence that and ( and ) transcription factor expression in an arc-shaped progenitor domain within the MGE promotes time-dependent survival of this neuroepithelium and the time-dependent specification of layer V SST CINs. and autonomously repress PV fate in MGE progenitors, in part through directly driving expression. These results have identified, in mouse, a transcriptional pathway that controls SST-PV fate.