Fig. 6. An example of roll turn performed by a lamprey with left hemisection of the spinal cord. (A,B) Side and top views for 30 consecutive frames. The level of hemisection is indicated in frame 1 (arrows). (C–E) The curvature plots for selected frames analogous to those used in Fig. 2. The roll turn is performed in steps. In frames 1, 12 and 25, the animal starts rolling to the right (start 1, 2 and 3). In frames 9, 19 the rolling decelerates (stop 1, 2). Data for the start moments are shown in red, and for the stop moments in blue. Note that in E most of the data points for the start moments are located in right ventral and left dorsal quadrants, and most of those for stop moments are located in left ventral and right dorsal quadrants, i.e. similar to Fig. 3E. R, right; L, left; D, dorsal; V, ventral sides of the body.