Recovery of the vertical vestibulo-ocular reflex gain in rabbits submitted to bilateral and unilateral visual deprivation from birth.
Rabbits were raised in complete darkness from birth to the age of 3 months. At this age, the animals were submitted to dynamic vestibular stimulation consisting of lateral sinusoidal oscillations of different frequencies and fixed amplitude. The vertical VOR, elicited in complete darkness, was then recorded. While the phase of the response was perfectly adequate to ensure head movements compensation, the gain values recorded were clearly reduced with respect to the values obtained in a normally raised control group of the same age. After exposure to light, the visually deprived animals showed a complete recovery of normal VOR gain values in a relatively short period of time. Another group of animals was submitted to monocular prolongation of light deprivation during the fourth month of life. After 2 weeks these rabbits displayed a clear unbalance of the VOR between the two eyes: the eye in which vision was allowed showed a complete recovery of VOR gain values, while the gain of the occluded eye remained unchanged. The present results confirm that visual experience in early life is necessary for a correct development of the VOR. If visual deprivation is limited to the first few months of life, the impairment of the reflex characteristics is completely reversible. Finally, data on monocular deprivation suggest that, in the rabbit, the neural structures which preside to the development of the vertical VOR compensatory properties are lateralized.
D000818:Animals; D003624:Darkness; D004558:Electric Stimulation; D009799:Ocular Physiological Phenomena; D010775:Photic Stimulation; D011817:Rabbits; D012018:Reflex / Q000502:physiology*; D013997:Time Factors; D014722:Vestibule, Labyrinth / Q000502:physiology*