Fig. 3
Example transient head rotations from (a) a healthy control, (b) preoperative, and (c) postoperative testing from the same patient in the gaze-stabilization exercise in the horizontal plane (yaw direction). The healthy control and the patient are the same as in the continuous head-movement examples shown in Fig. 2. Subjects were asked to move their heads in impulses while fixating on an imaginary target 1 m away (‘Imaginary target’ exercise), which required them to turn quickly from midline to one self-determined eccentric location (left and right sides of midline, interleaved), followed by a slow resetting head movement back to the midline, repeated. Compared with the continuous gaze-stabilization exercises, subjects needed to pause at eccentric locations and only the impulses were analyzed. The left panel shows the individual head-velocity traces throughout the first half-session of each trial. The middle panel shows head-velocity traces from individual head-rotation repetitions superimposed with the mean and standard deviation of the range of motion. The three insets on the right include histograms in the upper panel, which characterize the distribution of the cycle frequency and peak velocity parameterized from individual head-movement cycles of each example subject. The scatterplots in the lower panel visualize the cycle-frequency and peak-velocity changes from trial to trial. (d) The summary histograms superimpose the group average cycle-frequency and peak-velocity distributions. Asterisks indicate differences at three significance levels (* for p < 0.05, ** for p < 0.01, *** for p < 0.001, ns for insignificant difference).
