Figure 6.
Transmitter usage through sensory layers and specific circuits
(A) Schematic depicts the probabilistic graph traversal model used to “layer” different sensory systems, adapted from Schlegel et al.,74 underlying data from Dorkenwald et al.18 Starting from first-order central brain input neurons, we recorded the mean step (“layer”) at which each subsequent FAFB-FlyWire neuron is encountered by the simulation.18 Bar charts show transmitter input across distinguishable sensory systems.18 Bars normalized and binned by target neurons’ layer score (width 0.2); text reports neuron count. Kenyon cells are shown in pink and descending neurons, i.e., the last captured point of the sensory-motor transform in the brain, in brown so that the reader can compare layer progression between systems. Vertical line shows the mean descending neuron layer. Olfactory sensory neurons mispredicted for serotonin are corrected to acetylcholine.64 “Uncertain” neurons (see STAR Methods) were removed from this analysis.
(B) Feedforward and feedback connectivity across sensory systems by neuron-level transmitter prediction. For each unitary neuron-neuron connection (greater than 100) between a source and target neuron, we calculated a target-source layer difference: the layer value74 for the target neuron minus the layer value of the source neuron. Y axis gives the proportion of unitary connections in each bin (width 0.1).
(C) A potential circuit for righting the fly’s body axis relative to celestial cues. Purple arrow weight indicates activity level.
(D) A potential circuit for differential leg extension/retraction control.
(E) A potential circuit for steering away from unpleasant odors. Numbers give synaptic counts from HemiBrain.
See also Figure S4.