Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.30.361899v1?rss=1 Authors: Tomita, J., Ban, G., Kato, Y. S., Kume, K. Abstract: 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. We attempted to identify a novel sleep-regulating neuronal circuit in the central complex. no-bridgeKS49 mutant flies with an anatomical defect in the protocerebral bridge (PB) significantly decreased sleep. By transient activation of a subset of the PB neurons using 14 Gal4 drivers, we found the sleep-promoting R59E08-Gal4 and the wake-promoting R52B10-Gal4. The R59E08-Gal4 expressing PB neurons were identified as the PB interneurons according to their morphological features. On the other hand, using genetic mosaic analysis, we showed that activation of neurons projecting from the PB to the FB and contralateral NO (PFN neurons) in the R52B10-Gal4 driver reduced sleep. A targeted GFP reconstitution across synaptic partners (t-GRASP) analysis demonstrated synaptic contacts between the sleep-promoting PB neurons and the wake-promoting PFN neurons. Furthermore, we found that activation of a pair of dopaminergic neurons with axons projecting the PB (T1 DA neurons) significantly decreased sleep. The wake-promoting T1 DA neurons were more likely to physically associate with the sleep-promoting PB interneurons. Dopamine 2-like receptor (Dop2R) knockdown in the R59E08-Gal4 expressing PB interneurons significantly increased sleep. These results indicated that the neuronal circuit in the PB regulated by dopamine signaling mediates sleep-wakefulness. Copy rights belong to original authors. Visit the link for more info