Locomotor and exploratory behavior in the rat following bilateral vestibular deafferentation.

Despite many studies of the postural and ocular reflex deficits caused by chronic bilateral vestibular loss in rats and guinea pigs, there have been few systematic studies of the effects of vestibular loss on locomotor activity and exploratory behavior over a period of several months following the lesion. In this study, the authors quantified locomotor and exploratory behavior in an open field maze at 3 weeks, 3 months, and 5 months following bilateral vestibular loss in rats. As a result of bilateral surgical vestibular lesions, rats exhibited a persistent increase in locomotor velocity, duration, and distance traveled, with a marked tendency for increased inner field activity and reduced thigmotaxis. Rats without balance-sense were also found to spend less time exploring the environment, as indicated by a decreased frequency and duration of wall-supported rearings. These results suggest that sudden and complete loss of balance-sense has persistent and complex effects on the way that rats navigate through and explore the environment.