Transcriptomic diversity of amygdalar subdivisions across humans and nonhuman primates

The amygdaloid complex mediates learning, memory, and emotions. Understanding cellular and anatomical features specialized in the primate amygdala versus other mammals requires a systematic, anatomically resolved molecular analysis of neuron types. We analyzed five nuclear subdivisions of the primate amygdala with single-nucleus RNA sequencing in macaques, baboons, and humans to examine gene expression profiles for excitatory and inhibitory neurons. Integrated analyses across species identified diverse subtypes of glutamatergic and GABAergic neurons that are highly conserved across primates. Compositional analyses revealed that subdivisions of the primate basolateral complex contain distinct classes of glutamatergic neurons and divergent gene expression profiles for parvalbumin and somatostatin GABAergic neurons. Referencing primate neuron types to transcriptomic atlases of the murine amygdala highlighted primate-specific specializations for glutamatergic neurons and identified which neuron types are conserved across mammals and amygdalar subdivisions. Understanding the molecular heterogeneity of anatomically resolved amygdalar neuron types provides a cellular framework for improving models of how amygdalar circuits contribute to cognition and mental health.