CHRONIC RECORDING OF THE VESTIBULOOCULAR REFLEX IN THE RESTRAINED RATUSING A PERMANENTLY IMPLANTED SCLERAL SEARCH COIL

A technique is described which allows accurate long-term monitoring of eye movements in the rat using permanently implanted scleral search c oils. Search coils permanently sutured around the sclera yield vestibu le-ocular reflex (VOR) gain and phase values which are comparable to t hose reported previously in the literature using acutely implanted coi ls or electrooculographic electrodes. Considerations related to strain , sex and surgical procedures which permit measurement of responses in the chronically restrained rat are described. VOR gain and phase show a time course to their recovery following the implant surgery, with a symptotic performance typically attained approximately 20 days post-su rgically. This technique, with the ability to monitor eye movements ov er weeks to months, appears ideal for development of rodent models of reflex adaptation which require observation of reflex behavior over ex tended periods of time. Development of a chronic procedure for monitor ing eye movement in rodents is especially important given their initia l response to restraint (extensive struggling). Finally, adaptation of this technique to smaller species (e.g., mouse) appears technically f easible which should permit the application of transgenic and knockout techniques to the determination of various vestibular reflex function s requiring long-term monitoring. (C) 1998 Elsevier Science B.V. All r ights reserved.