Fig. 5.

Raw data. Top row: head velocity (black dashed lines) and eye velocity (black solid lines) traces. Bottom row: corresponding head position (black dashed lines), eye position (black solid lines), and gaze (gray lines) traces. A and E: responses to passive head impulses in a representative patient. B and F: responses to active head impulses in the same patient. Mean gain increases from 0.24 in passive impulses to 0.61 in active impulses (P < 0.001); saccade precision increases from 0.59 to 1 (P < 0.001). Saccades are triggered with lower latency and are more accurate, so that gaze error is mostly compensated with a single movement, while in passive head impulses the patient needs a second correction. C and G: passive head impulses in all patients in HRG movements with peak head velocities ranging between 150 and 200°/s. D and H: passive head impulses in all patients in LRG movements with peak head velocities ranging between 150 and 200°/s. Mean gain is 0.18 in LRG and 0.55 in HRG impulses. Saccade precision is 0.51 in LRG and 0.81 in HRG impulses. In HRG movements gaze error is mostly corrected with a single covert saccade, while in LRG at least two corrections are required.