Search

Within the vertebrate neocortex and other telencephalic structures, molecularly-defined neurons tend to segregate at first order into inhibitory (GABAergic) and excitatory (glutamatergic) types. We used single-nucleus RNA sequencing, analyzing over 2.4 million brain cells sampled from 16 locations in a primate (the common marmoset) to ask whether (1) neurons generally segregate by neurotransmitter status, and (2) neurons expressing the same neurotransmitters share additional molecular features in common, beyond the few genes directly responsible for neurotransmitter synthesis and release. We find the answer to both is “no”: there is a remarkable degree of transcriptional similarity between GABAergic and glutamatergic neurons found in the same brain structure, and there is generally little in common between glutamatergic neurons residing in phylogenetically divergent brain structures. The origin effect is permanent: we find that cell types that cross cephalic boundaries in development retain the transcriptional identities of their birthplaces. GABAergic interneurons, which migrate widely, follow highly specialized and distinct distributions in striatum and neocortex. We use interneuron-restricted AAVs to reveal the morphological diversity of molecularly defined types. Our analyses expose how lineage and functional class sculpt the transcriptional identity and biodistribution of primate neurons.One-Sentence SummaryPrimate neurons are primarily imprinted by their region of origin, more so than by their functional identity.