Fig. 8.
Translational vestibulo-ocular reflex (VOR) elicited during translations along axes in the horizontal plane. A and B: 3-dimensional axis of right and left eye velocity recorded from 6 chinchillas during translations along eight axes in the horizontal plane is illustrated (A), with the normalized vectors (B). Each vector represents the single frequency discrete Fourier transform fit of the eye velocities elicited during the positive peak of acceleration of a 1-Hz sinusoidal translation in the horizontal plane (φ = 90°) with peak 2 or 3 m/s2. C: the color of the vector indicates the theta of the translation axis and the peak positive acceleration is in the direction of the arrows, as illustrated. Data for each animal are represented with the markers described in the legend in B. Translations along axes approximately aligned with the right eye’s resting line of sight (θ = −30°, −45°, −60°) produce a larger magnitude eye movement in the right eye than the left. Conversely, translations along axes approximately aligned with the left eye (θ = +60, +45, +30) elicit larger eye velocities from the left eye. D: this is further emphasized where the ratio of right/left eye velocity is shown. E: boxplots show component-wise responses grouped by θ for the eye movements elicited by both 2 m/s2 (brown) and 3 m/s2 (purple). Outliers greater than three times the interquartile range were removed for D and E (fewer than 16 of 257 samples were removed for each plot). Nonlinear mixed-effect models were created to predict each component of eye movement and the ratio of right eye/left eye magnitude based on the magnitude of translation and the theta of the translation axis with a random effect of chinchilla ID number. The fits for each component of eye movement during 2 and 3 m/s2 translations are shown in brown and purple in E and the fit for the ratio of right/left eye velocity is shown in red in E. All model results had root means square error ≤0.74. All fit parameters are detailed in Table 2. Each axis of translation for each amplitude (i.e., each individual box and whisker plot has n ≥ 11).