A multimodal cell census and atlas of the mammalian primary motor cortex

Discovering and mapping brain cell types is necessary for understanding brain architecture, development, function, and disease. Rigorous quantitative neuron-type definitions have remained elusive because neurons are locally and projectionally heterogeneous. An integrated mouse, marmoset, and human primary-motor-cortex atlas connected molecular taxonomies with spatial, morphological, physiological, connectivity, developmental, and regulatory features while identifying a conserved hierarchical transcriptomic taxonomy.