Fig. 1: Drosophila melanogaster circadian clock network.

A Clk856-Gal4 drives GFP expression in most of the circadian clock neurons and some non-clock neurons (asterisk). Only a few DN₃ are included in this Gal4-line. Scale bar = 50μm. B Drosophila clock neurons can be divided into four classes each of Dorsal neurons (DN) and Lateral neurons (LN) based on their cell body location. These can be further subdivided into different cell types based on their morphology and gene expression. Subtypes of clock neurons are color-coded. This color code is used throughout the manuscript. C Classification and numbers of all clock neurons identified in the FlyWire connectome. Refer to Table 1 for details. D The morphology of identified clock neurons in the connectome largely resembles the morphology of clock neurons marked by Clk856-Gal4. E Broad synaptic interconnectivity between different cell types within the clock network. The direction of the arrow indicates the flow of information. Strong connectivity is observed from DN_1a to LN^ITP, from s-CPDN₃C and s-CPDN₃D to DN_1pC-E, as well as from DN_1pA to LN^ITP, LN_d^CRY+, s-CPDN₃C and s-CPDN₃D. Note extensive contralateral connectivity between different cell types, most of which can be accounted for by the DN_1pA. The dashed line indicates the brain midline. F Individual DN_1pA in the right hemisphere forms both ipsilateral and contralateral connections with s-CPDN₃C, s-CPDN₃D, LN_d^CRY+, and LN^ITP. Source data for panels E and F are provided in the Source Data file. Brain mesh is from Dorkenwald et al., 2024.