Since the beginning of the project, significant progress has been made in understanding neuronal identity and cortical area specification. In WP1, we tracked the emergence of area-specific molecular identities in progenitors and neurons, analyzing single-nuclei RNA sequencing data and spatial gene expression. We identified molecular spatial patterns that are conserved across development, inherited from progenitors, or emerge during postmitotic maturation. In WP2, we performed transplantation experiments to manipulate neuronal identity, using Patch-seq to analyze molecular, morphological, and electrophysiological properties. We also performed environmental manipulations in vivo, demonstrating the remarkable stability of neuronal identity despite changes in positioning and innervation. In WP3, we assessed molecular identity robustness in vitro, showing that glutamatergic neurons lose identity-defining gene expression and diversity in 2D cultures but retain them in organotypic slices, highlighting the role of extracellular context. In WP4, we investigated postnatal sensory experience in neuronal identity acquisition, determining the timeline of upper-layer neurogenesis in Acomys dimidiatus. We conducted single-nuclei RNA sequencing analyses, revealing mosaic maturation of neuronal subtypes and cortical areas. Ongoing transcriptomic, histological, and electrophysiological studies aim to further characterize these findings. Overall, our work demonstrates the interplay between genetic and environmental factors in shaping neuronal identity and diversity.
