Example trace of jGCaMP7f activity of EPG neurons in the protocerebral bridge (PB). Left, EPG Δ F / F 0 over time. Middle, bar position (that is, the inverse of the fly’s heading angle) (black) and the EPG phase estimate (grey). Shaded area represents the 90° gap where the bar is not visible. Right, forward walking velocity. The top trace shows a time period during which the fly meandered rather than performing menotaxis. The bottom trace shows a later moment, when the same fly maintained a relatively consistent heading angle.
