Hub-organized parallel circuits of central circadian pacemaker neurons for visual photoentrainment in Drosophila

• DOI: 10.1038/s41467-018-06506-5
• Publication Date: 2018-10-08T11:06:51Z
• Authors: Meng-Tong Li; Li-Hui Cao; Na Xiao; Min Tang; Bowen Deng; Tian Yang; Taishi Yoshii; Dong-Gen Luo
• Keywords: Neurons; 0303 health sciences; 03 medical and health sciences; Biological Clocks; Science; Q; Animals; Drosophila Proteins; Drosophila; Visual Pathways; Article; Circadian Rhythm

AbstractCircadian rhythms are orchestrated by a master clock that emerges from a network of circadian pacemaker neurons. The master clock is synchronized to external light/dark cycles through photoentrainment, but the circuit mechanisms underlying visual photoentrainment remain largely unknown. Here, we report that Drosophila has eye-mediated photoentrainment via a parallel pacemaker neuron organization. Patch-clamp recordings of central circadian pacemaker neurons reveal that light excites most of them independently of one another. We also show that light-responding pacemaker neurons send their dendrites to a neuropil called accessary medulla (aMe), where they make monosynaptic connections with Hofbauer–Buchner eyelet photoreceptors and interneurons that transmit compound-eye signals. Laser ablation of aMe and eye removal both abolish light responses of circadian pacemaker neurons, revealing aMe as a hub to channel eye inputs to central circadian clock. Taken together, we demonstrate that the central clock receives eye inputs via hub-organized parallel circuits in Drosophila.