FOXG1 drives transcriptomic networks to specify principal neuron subtypes during the development of the medial pallium

The medial pallium (MP) is the major forebrain region underlying learning and memory, spatial navigation, and emotion; however, the mechanisms underlying the specification of its principal neuron subtypes remain largely unexplored. Here, by postmitotic deletion of FOXG1 (a transcription factor linked to autism and FOXG1 syndrome) and single-cell RNA sequencing, we found that FOXG1 controls the specification of upper-layer retrosplenial cortical pyramidal neurons (RSC-PyNs (UL)), subiculum PyNs (SubC-PyNs), CA1-PyNs, CA3-PyNs and dentate gyrus granule cells (DG-GCs) in the mouse MP. We uncovered subtype-specific and subtype-shared FOXG1-regulated transcriptomic networks orchestrating MP neuron specification. we conducted scRNA-seq of 27198 cells sampled from the medial pallium of Foxg1fl/fl and Nex-Cre; Foxg1fl/fl mice at E17.5