File:The-Angular-Interval-between-the-Direction-of-Progression-and-Body-Orientation-in-Normal-Alcohol-pone.0076257.s001.ogv

English: The angular interval between an intact fly's direction of progression (direction of shift of weight of the fly's centre of gravity) and its orientation (the direction of the fly's front). The front of the fly is represented by the orientation of the thick red bar. The direction and magnitude of progression (also termed the velocity vector) are represented by the thin blue line attached to the forepart of the thick bar. As shown, weight is shifted first, in a new direction, and front converges or tends to converge to the new direction established by the weight shift (which is also the direction of progression). The angular interval is generated by the direction of progression vector moving away from the direction of front. The angular interval is reduced or nullified by the tendency of the front vector to rotate and align with the direction of progression. Note the small magnitude of the angular interval and of the velocity magnitude in this intact fly (“high gain”) compared to the large magnitude of these values in the cocaine treated fly in video S2.