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. Author manuscript; available in PMC: 2020 Nov 25.
Published in final edited form as: Nat Neurosci. 2019 Jul 22;22(9):1460–1468. doi: 10.1038/s41593-019-0444-x

Figure 6. Flies slow down and turn to bring their E-PG activity back to its previous position in the protocerebral bridge after it is rotated via neural stimulation.

Figure 6.

a, How does the fly react to a chemogenetically-stimulated change in its E-PG phase? See text for details on possible behavioral outcomes. b-c, We stimulated a different central-complex cell type, P-ENs14,25,26, by expressing in them an ATP-gated ion channel (P2X2) and puffing ATP with a pipette on specific glomeruli in the protocerebral bridge, while imaging E-PGs as flies walked in the dark. Stimulating P-ENs reliably repositions the E-PG phase medial to the stimulated P-EN glomerulus14 (Video 3, 4). d-e, E-PG activity (left), E-PG phase and fly heading (middle), and forward walking (right), during individual stimulation events. Red dashed lines mark stimulation time, red arrows mark stimulation position in the bridge. Black arrows highlight the fly turning and slowing down in response to stimulation. f, Mean and s.e.m. of turning velocity over time during events when our stimulation was positioned either clockwise or counterclockwise (45° to 135° away) relative to the initial E-PG phase. The initial E-PG phase is defined as the mean E-PG phase in the 10 s window before stimulations. g, Mean turning velocity for each fly before (−2 to 0 s) and after (0 to 2 s) stimulation (CCW: p=3e-3, 11 flies; CW: p=2e-2, 15 flies; two-sided Wilcoxon signed-rank test). The same flies were analyzed for both CCW and CW trials, only some flies by chance did not receive CCW or CW trials. h, Mean and s.e.m. of forward velocity over time when our stimulation was positioned either near (<120°) or far (>120°) from the initial E-PG phase. i, Mean forward velocity for each fly before (−10 to 0 s) and after (0 to 10 s) stimulation (near: p=4.9e-2, 17 flies; far: p=3e-4, 17 flies; two-sided Wilcoxon signed-rank test).We analyzed the 77% of trials where the E-PG phase was maintained at a relatively stable angle (circular s.d. < 45°) for 10 s prior to ATP stimulation, as an indication that flies were performing arbitrary-angle fixation with respect to their E-PG phase. No forward walking requirements were applied to this figure. CW: clockwise. CCW: counterclockwise.