Fig. 4: Direct and indirect clock output pathways.

A Clock output grouped by the nine neuronal super classes annotated in the FlyWire connectome. Intrinsic neurons, specifically the central neurons, are the largest group of neurons downstream of clock neurons. B Breakdown of outputs from different types of clock neurons. All clock neurons, except for l-LN_v, provide a majority of their output to central neurons. l-LN_v mostly provides inputs to optic neurons. C Neurons from the four different super classes (central, optic, visual projection, and visual centrifugal) which receive inputs from the clock. D Individual postsynaptic partners of DN_1pA and s-CPDN₃C-D are sorted based on the number of synapses. Postsynaptic clock neurons are colored based on their identity. E CRY-positive DN_1pA provide major inputs to CRY-negative DN_1pC-E via s-CPDN₃C-D. Contralateral connections from DN_1pA to s-CPDN₃ are stronger than ipsilateral connections. F APDN₃ forms the most output synapses in the clock network and is highly connected to several types of Clamp neurons (CL). G DN_1pB-E provides strong outputs to Tubercle-innervating neurons. H Several clock neurons provide strong inputs to neurons from diverse neuropils. Mono- and di-synaptic clock inputs to neurons associated with the I central complex, J mushroom bodies, and K neurosecretory cells. Note that there are only a few direct connections from the clock to downstream higher brain centers. Numbers above the arrows indicate the number of synapses and numbers in circles indicate the number of neurons. Note: all numbers refer to neurons across both hemispheres. For C–I, cell types are listed according to the strength of the clock input (from high to low). EB ellipsoid body, FB fan-shaped body, NO noduli, EPG ellipsoid body-protocerebral bridge-gall neuron, PFGs protocerebral bridge glomerulus-fan-shaped body-ventral gall surround, KC Kenyon cell, DAN dopaminergic neuron, MBON mushroom body output neuron, SEZ-NSC suboesophageal neurosecretory cells, l-NSC lateral neurosecretory cells, m-NSC medial neurosecretory cells. Source data for panels B–K are provided in the Source Data file. Brain mesh is from Dorkenwald et al., 2024.