Extended Data Fig. 2: PFN_d and PFN_v activity bumps in the bridge are phase aligned with the EPG heading signal.

a, Sample trace, in tethered flight without optic flow, of simultaneously imaged GCaMP6m in EPG cells and jRGECO1a in PFN_d cells reveals that the activity bumps of these two cell classes are phase aligned in the bridge. b, Probability distribution of the EPG - PFN_d phase in tethered flight without optic flow. In this panel and throughout, the single fly data are in light gray and the population mean is in black. c, d, Same as panels a, b, but for GCaMP6m in EPG cells and jRGECO1a in PFN_v^cells. e, Top three rows, sample trace of simultaneously imaged GCaMP6m in EPG cells and jRGECO1a in PFN_v cells in a tethered, flying fly experiencing optic flow (in the time window bracketed by the vertical dashed lines) with foci of expansion that simulate the following directions of travel: −120°, 0° (forward), 120°. Bottom, circular-mean phase difference between EPG cells and PFN_v cells. f, Probability distribution of the EPG - PFN_v phase under three optic flow conditions. g, Circular mean of the EPG – PFN phase and s.e.m. under different visual stimulus conditions. Watson-Williams multi-sample tests, P>0.66 when comparing any experimental group with 0°. Note that we only collected a full EPG-PFN, dual-imaging data set with optic flow (moving dots) with PFN_v cells because, for reasons that are not fully clear, the jRGECO1a signal was too weak in PFN_d cells to properly estimate the PFN_d phase outside of the context of stationary dots (i.e., during optic flow). When imaging PFN_d cells with a split-Gal4 driver and with GCaMP rather than with jRGECO1a (e.g., Fig. 3j–l), the signal is much brighter.