Fig. 8.
Simultaneous recording of head and eye movements. Recording conditions were as described in Fig. 1C. Visual stimuli are sinusoidal vertical bars of contrast = 1, spatial frequency = 0.2 cycle/° moving at speed = 12°/s, reversing direction every 5 s (A and B, bottom panels). Two C57Bl6 Brn3bWT/WT mice were used for these recordings. Eye angles were calculated from the images acquired by the side camera, using a conversion based on a spherical eye model and ignoring perspective distortion. Head angles were calculated as for all previous OMR experiments, using the data provided by the top camera. A: simultaneous recording of both eyes and head. Top 3 panels represent angular velocities for left eye, right eye, and head. Tracking phases (green) and reset phases (magenta) were semiautomatically annotated. Eye velocities for the two marked tracking phases (magenta cross and asterisk) are indicated in the scattergram in E. B: example of recording in which large head movements prevented collection of meaningful images for the left eye (middle panel) and only intermittent focused eye images for the right eye (top panel). Periods during which the right eye was out of focus are marked as gray dotted lines. Note different y-scales for the different plots. Bottom panels of A and B show stimulus positions plots. C: velocity of head and eye movements (tracking phases where collected from 7 recordings, 1 min each). The histograms depict the distribution of head and eye velocities. All recordings where at least one eye was in focus were analyzed. D: histogram of combined (head + eye) velocities for the observations shown in C. E: the relative angle covered during individual tracking phases by left (y-axis) and right (x-axis) eyes, expressed as a percentage of head movement. Tracking phases were collected from 5 recordings, 1 min each, in cases where both eyes and the head were in focus. A linear regression line is shown (green; R2 = 0.76).