Heterogeneous pericoerulear neurons tune arousal and exploratory behaviours.

As the primary source of noradrenaline in the brain, the locus coeruleus (LC) regulates arousal, avoidance and stress responses(1,2). However, how local neuromodulatory inputs control LC function remains unresolved. Here we identify a population of transcriptionally, spatially and functionally diverse GABAergic (γ-aminobutyric acid-producing) neurons in the LC dendritic field that receive distant inputs and modulate modes of LC firing to control global arousal levels and arousal-related processing and behaviours. We define peri-LC anatomy using viral tracing and combine single-cell RNA sequencing with spatial transcriptomics to molecularly define both LC noradrenaline-producing and peri-LC cell types. We identify several neuronal cell types that underlie peri-LC functional diversity using a series of complementary neural circuit approaches in behaving mice. Our findings indicate that LC and peri-LC neurons are transcriptionally, functionally and anatomically heterogenous neuronal populations that modulate arousal and avoidance states. Defining the molecular, cellular and functional diversity of the LC and peri-LC provides a roadmap for understanding the neurobiological basis of arousal, motivation and neuropsychiatric disorders.