TY - JOUR TI - Connectomic analysis of the Drosophila lateral neuron clock cells reveals the synaptic basis of functional pacemaker classes AU - Shafer, Orie T AU - Gutierrez, Gabrielle J AU - Li, Kimberly AU - Mildenhall, Amber AU - Spira, Daphna AU - Marty, Jonathan AU - Lazar, Aurel A AU - Fernandez, Maria de la Paz A2 - Desplan, Claude A2 - Helfrich-Förster, Charlotte VL - 11 PY - 2022 DA - 2022/06/29 SP - e79139 C1 - eLife 2022;11:e79139 DO - 10.7554/eLife.79139 UR - https://doi.org/10.7554/eLife.79139 AB - The circadian clock orchestrates daily changes in physiology and behavior to ensure internal temporal order and optimal timing across the day. In animals, a central brain clock coordinates circadian rhythms throughout the body and is characterized by a remarkable robustness that depends on synaptic connections between constituent neurons. The clock neuron network of Drosophila, which shares network motifs with clock networks in the mammalian brain yet is built of many fewer neurons, offers a powerful model for understanding the network properties of circadian timekeeping. Here, we report an assessment of synaptic connectivity within a clock network, focusing on the critical lateral neuron (LN) clock neuron classes within the Janelia hemibrain dataset. Our results reveal that previously identified anatomical and functional subclasses of LNs represent distinct connectomic types. Moreover, we identify a small number of non-clock cell subtypes representing highly synaptically coupled nodes within the clock neuron network. This suggests that neurons lacking molecular timekeeping likely play integral roles within the circadian timekeeping network. To our knowledge, this represents the first comprehensive connectomic analysis of a circadian neuronal network. KW - circadian rhythms KW - connectomics KW - clock networks JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -