Protocerebral bridge neurons that regulate sleep inDrosophila melanogaster

The central complex is one of the major brain regions that control sleep in Drosophila , but the circuitry details of sleep regulation have yet to be elucidated. Here, we show a novel sleep-regulating neuronal circuit in the protocerebral bridge (PB) of the central complex. Activation of the PB interneurons labeled by the R59E08-Gal4 and the PB columnar neurons in the R52B10-Gal4 promoted sleep and wakefulness, respectively. A targeted GFP reconstitution across synaptic partners (t-GRASP) analysis demonstrated synaptic contacts between these two groups of sleep-regulating PB neurons. Furthermore, we found that activation of a pair of dopaminergic (DA) neurons projecting to the PB (T1 DA neurons) decreased sleep. The wake-promoting T1 DA neurons and the sleep-promoting PB interneurons formed close associations. Dopamine 2-like receptor ( Dop2R ) knockdown in the sleep-promoting PB interneurons increased sleep. These results indicated that the neuronal circuit in the PB regulated by dopamine signaling mediates sleep-wakefulness.