Extended Data Fig. 5 |. smFISH validation of graded gene expression in PVALB⁺ interneurons.

a, Top, sagittal sections of marmoset brain (n = 1 marmoset, at least two tissue sections stained per probe set) stained for PVALB and ASS1 (left) or CRYM (right), two genes that showed quantitatively graded expression in the interneuron snRNA-seq data (see Fig. 2d). Bottom, representative cells from each of the three imaged regions (blue boxes in the top panels). Scale bar, 10 μm. b, Top, spatial distribution of PVALB⁺ and double-positive interneurons plotted from three imaging windows (blue boxes in a) across the sagittal plane. Bottom, proportion of single-positive (PVALB⁺ only) and double-positive (PVALB⁺ASS1⁺ or PVALB⁺CRYM⁺) cells binned along the rostrocaudal axis within imaged regions. c, Mean intensity for each probe within cells identified in b (n = 14,195 double-positive cells in the PVALB⁺ASS1⁺ experiments and n = 26,194 double-positive cells in the PVALB⁺CRYM⁺ experiments). PVALB itself shows a graded expression (in terms of signal intensity per cell) across the rostrocaudal extent in our snRNA-seq data, with the highest expression (and highest cell numbers) located in the caudal pole (V1). Box plots represent the interquantile range and median values.