Anticompensatory fast phases of the vestibulo-ocular reflex in cats

This study shows that there are substantial differences in the anticompensatory fast phases (AFPs) of the horizontal and vertical vestibule-ocular reflex. Indeed the cumulative amplitude of the AFPs in the horizontal plane increases by increasing the stimulus velocity. This effect result from the increase of the AFP amplitude while the AFP frequency is unchanged. In contrast, the cumulative amplitude of the AFPs in the vertical plane is smaller compared to the horizontal plane and shows a smaller increase when increasing the stimulus velocity due to an increase of frequency. These differences are deemed to result to the shape of the maximum receptor density region of the retina. Since the major axis of this region is oriented horizontally, horizontal AFPs can displace the eye within a much wider range compared to vertical AFPs in order to keep the image within the area of maximum receptor density.