During animal locomotion or position adjustments, the visual system uses image stabilization reflexes to compensate for global shifts in the visual scene. These reflexes elicit compensatory head movements (Optomotor response - OMR) in unrestrained animals or compensatory eye movements (Optokinetic response - OKR) in head fixed or unrestrained animals, exposed to globally rotating striped patterns. In mice, OMR responses are relatively easy to observe and find broad use in the rapid evaluation of visual function. OKR determinations are more involved experimentally but yield more stereotypical, easily quantifiable results. The relative contributions of head and eye movements to image stabilization in mice have not been investigated. We are using newly developed software and apparatus to accurately quantitate mouse head movements during OMR, eye movements during OKR, and determine eye movements in freely behaving mice. We provide the first direct comparison of OMR and OKR gains (head or eye velocity / stimulus velocity), and find that the two reflexes have comparable dependencies on stimulus luminance, contrast, spatial frequency and velocity. OMR and OKR are similarly affected in genetically modified mice with defects in Retinal Ganglion Cells, as compared to wild types, suggesting they are driven by the same sensory input (RGC type). OKR eye movements have much higher gains than the OMR head movements, but neither can fully compensate global visual shifts. However combined eye and head movements can be detected in unrestrained mice performing OMR, suggesting they can cooperate to achieve image stabilization, as previously described for other species.
- Optomotor Response
- Optokinetic response
- Optokinetic Nystagmus
- Direction Selective RGCs
- Copyright © 2017, Journal of Neurophysiology