show Abstracthide AbstractThe amygdala or amygdala-like structure in the brain are found in all vertebrates, and plays a critical role for emotional processing. But the cellular architecture of amygdala and how they evolved are still elusive. Here, we generated single-nucleus RNA-sequencing data for more than 200,000 cells in human, macaque, mouse and chicken amygdala. Abundant neuronal cell types derived from different subnuclei of amygdala were identified in all datasets. Cross-species analyses revealed GABAergic neurons and GABAergic neuron-enriched subnuclei of amygdala were well-conserved in cellular composition and marker gene expression, whereas glutamatergic neuron-enriched subnuclei were relatively divergent. Furthermore, we discovered that LAMP5+ interneurons were much more numerous in primates, while DRD2+ GABAergic neurons, LAMP5+ and SATB2+ glutamatergic neurons were predominant in the human central amygdalar nucleus (CEA) and basolateral amygdala complex (BLA), respectively. In addition, we also identified GABAergic neuron-enriched subnuclei of amygdala in the chicken. Altogether, our study highlight extremely cell-type diversity in the amygdala across species and their species-specifc adaptations. Overall design: To transcriptomically characterize cell types of the amygdala in mammals and sauropsids, which have been the most diverse and successful group of land vertebrates, we applied snRNA-seq assays (Chromium v3) and focused on human, macaque, mouse and chicken. Human samples were from postmortem donors with very short postmortem interval (within 6 hours), and macaque, mouse and chicken amygdala were freshly dissected. We profiled a total of 17 specimens, including 3 human amygdala samples, 3 macaque amygdala samples, 2 chicken amygdala homolog samples, 4 mouse amygdala samples, 3 mouse basolateral amygdala complex (BLA; made up of the lateral (LA), basal (BA) and basomedial (BM) nucleus) samples, and 2 mouse central amygdalar nucleus (CEA) samples