Fig. 6: The EC stream mainly supplies CGE-derived LAMP5⁺ interneurons.

a, Samples collected for snRNA-seq. b–e, Uniform manifold approximation and projection (UMAP) plots of maturing interneurons showing the sample origin (b), donor age (c), subpallial lineages (d) and mature neuronal types (e). f, Heat map of the top differentially expressed (DE) protein-coding genes in each cell identity shown in d,e. g, Top row, main maturation trajectories inferred from Monocle. Bottom row, histograms showing the contributions of each sample origin to each trajectory along pseudotime. h, Number of cells from the EC stream in each of the trajectories shown in g. i, Spatial transcriptomic label transfer²⁴ identifies superficial- and deep-layer LAMP5⁺ subpopulations. j, Volcano plot of a DE analysis (quasi-likelihood F-test based on pseudobulk counts aggregated by donor) between superficial-layer (blue) and deep-layer (magenta) LAMP5⁺ interneurons. k, Module scores for superficial- and deep-layer LAMP5⁺ cells. Density lines drawn for non-EC stream cells (grey; see Extended Data Fig. 13). l, At birth, LAMP5⁺DCX⁺ (arrows) and LAMP5⁺COUPTFII⁺ (arrowheads) young neurons are present in the EC stream and in the EC. m, At birth, RELN⁺DCX⁺COUPTFII⁺ cells are present in streams of migrating neurons close to the ventral temporal lobe VZ. In the EC, many RELN⁺ cells express COUPTFII and a subset are DCX⁺ (arrow). n, Top, maps of cells in the EC at birth co-expressing markers of CGE-derived (COUPTFII⁺) interneuron subpopulations: LAMP5, RELN, calretinin (CR) and VIP. Bottom, their frequency distribution across cortical layers. Scale bars, 50 µm (l); 1 mm (n); 100 µm (m top right); 20 µm (m bottom right).