Octopamine regulates neural circuits in the mushroom body and central complex, influencing sleep and arousal

Sleep is a widespread yet incompletely understood phenomenon, and animals exhibit diverse arousal states beyond the simple binary of sleep and wake. Essential behaviors such as feeding, courtship, and escape often compete with sleep, and biogenic amines-including dopamine, norepinephrine, and serotonin-help regulate these behavioral states across species. Here, we leverage the small number and well-defined connectivity of neuromodulatory neurons in Drosophila to investigate how specific octopamine (OA) neurons regulate sleep and arousal. We focus on a pair of OA neurons, VPM3, which project broadly to the mushroom body (MB) and central complex (CX). We find that VPM3 neurons are sexually monomorphic, required for sleep suppression and male courtship, and modulated by sleep history. In addition, the male-specific fruitless isoform in these neurons is necessary for sleep regulation. Combining connectomics with targeted genetic manipulations, we identify key inputs from the CX, MB-mediated downstream pathways, and OA receptor signaling that together reveal how OA circuits coordinate sleep and arousal states.