Fig. 5: Downstream circuits of Canon neurons.
a A bar graph showing percent of total presynapses of A2–A3 Canon neurons that target the indicated downstream neuron. Major partners (occupying more than 2.5% of total presynapses) are shown. b, c Dorsal view (b) and anterior view (c) of EM reconstructed A31k and Canon neurons. d Serial EM images showing synapses between Canon (cyan) and A31k (magenta) neurons. White arrows indicate T-bars. The images show representative synapses of observed 20 synapses from Canon to A31k neurons. e A circuit diagram from Canon neurons to muscles. Gray dotted lines indicate boundaries of neuromeres. Arrows with triangle heads indicate excitatory synaptic connections, lines with bar heads inhibitory synaptic connections and those with diamond-shaped heads glutamatergic synapses. Numbers next to the lines show the number of synapses. f Expression of CsChrimson driven by R20A03-Gal4, cha3.3-Gal80. The image shows representative datum from one of three independent experiments that gave similar results. g Time-lapse images of experimental larvae during optogenetic activation. The larva halted immediately with its body relaxed when exposed to red light. 0 s represents the onset of photostimulation. h Quantification of the number of forward peristalses during the first 2 s of light stimulation. n = 10 larvae in each group. All larvae in the experimental group stalled upon light stimulation, while control (ATR−) larvae were unaffected. ****p < 0.0001. p = 1.08 × 10−5, the two-sided Fisher exact test. i Plots of calcium signals in aCC MNs and GVLIs during fictive backward locomotion. Scale bars, 500 nm (d), 50 μm (f), and 1 mm (g).
