A fly displays a prolonged turning response during and after the presentation of a wide-field drifting grating stimulus, indicating the presence of an integration step in the flight control system. Simultaneously aquired GCaMP6f responses in visual interneurons follow a similar time course. Maximal z projection of an anatomical stack of the same fly is shown for reference. This video plays back at 1/4 actual speed. For additional information see Schnell et al. (2014) PNAS.