In the hippocampus and olfactory regions, long-range projecting GABAergic neurons and immature migrating populations create a diverse set of supertypes, including transitional types linking immature to mature states and region-specific Calb1+, Calr+, and dopamine-co releasing interneurons.

In the striatum, MSNs resembling D1 and D2 types emerge as seven LGE-derived subclasses, with subtypes expressing Drd1, Drd3, or both, and co-expression patterns suggesting mixed identities; these subtypes form distinct patches and streaks across striatal and pallidal borders.

Two organizational principles stand out: long-distance dispersion is common among telencephalic GABAergic neurons, and postnatal diversification varies by region, shaping regional circuit function.

Researchers integrated high-resolution whole-brain atlas data with prenatal and postnatal scRNA-seq to define a taxonomy of telencephalic GABAergic neurons, identifying 39–90 subclasses across seven main classes, totaling 284 supertypes and 1,051 clusters from over 611,000 cells.

In the cortex, CTX–CGE GABA and CTX–MGE GABA dominate, with about 10% of CTX-derived GABA neurons from POA; this includes Vip, Sncg, Lamp5, Sst, Pvalb, chandelier types and a newly defined RHP–COA Ndnf Gaba subclass enriched in hippocampal, olfactory, entorhinal, and CTXsp regions.

GABAergic neurons originate from five subpallial domains (MGE, CGE, LGE, septum, POA) and migrate to forebrain regions, with transcription factors and morphogens guiding fate and diversification.

The study characterizes long-range and local projection patterns, noting rare broadly distributed Pvalb+ and Sst+ subtypes and regionally restricted subtypes in olfactory bulb, hippocampus, entorhinal cortex, and cortex, underscoring complex telencephalic integration.

A newly defined MGE-derived Lamp5 Lhx6 Gaba subclass reassigns from CGE origins to MGE based on Lhx6 expression, illustrating cross-regional presence of MGE-type interneurons in olfactory and cortical areas.

CNA (cerebral nuclei) reveal four major GABAergic neuron classes in striatum and pallidum (CNU–MGE GABA, CNU–LGE GABA, LSX GABA, CNU–HYa GABA), with subtypes spanning dorsal/ventral striatal regions and pallidal areas, including cholinergic and co-releasing GABA/glutamate populations.

The study delivers a comprehensive transcriptomic and spatial atlas of GABAergic neuron types across the mouse telencephalon, linking developmental origins and adult distribution to understand how interneuron diversity supports cortical and subcortical circuits.

Overall, this work provides the most complete taxonomy to date of telencephalic GABAergic neurons, connecting adult cell identities to developmental origins and spatial distribution, and offering a framework for how inhibitory diversity underpins brain function across the mouse telencephalon.