Extended Data Fig. 10: A traveling-direction signal computed via optic flow is robust to changes in the yaw angle of the fly’s head.
From: Building an allocentric travelling direction signal via vector computation
a, A fly flying straight with the head aligned to the body axis. EPG and h∆B signals are aligned in the ellipsoid body and fan-shaped body, respectively. b, A fly flying straight forward with the head rotated 20° to the right. The EPG bump–assuming the EPG bump position tracks the fly’s head (rather than body) direction–will rotate 20° counterclockwise. The h∆B bump, however, will remain pointing in the same allocentric traveling direction because the net effect of the EPG bump rotating 20° in one direction and the ego-motion signal from optic flow (not represented in the diagram) rotating 20° in the opposite direction is that the PFR/h∆B bump stably indicates the same traveling direction throughout.
