[Changes and compensation in the locomotor pattern of unilateral vestibular neurectomized cats]

In the present study the locomotor activity of unilateral vestibular neurectomized cats while crossing over a rotating beam along its longitudinal axis at different speeds was investigated. The kinematics of the body movement was recorded by means of a motion analysis system, with an optical automatic TV-image processor (E. L. I. T. E system) allowing a computer reconstruction of the 3 dimensional motion. Analysis was focused on the locomotion pattern as defined by several parameters including step length, step frequency and velocity, and an estimate of the height of the body gravity center. The results obtained with non-rotating beam showed that unilateral vestibular neurectomy induced significant changes in locomotor activity of the lesioned cats. Animals crossed over the beam with very slow locomotion speed and they typically exhibited a strong reduction in step length associated with a decrease in frequency. In addition, the gravity center of the walking cats was lower than the normal. The analysis performed with the rotating beam revealed different strategies of compensation, with cats moving either faster or slower as compared to their preoperative performance. Such strategies in locomotion speed regulation avoided falling from the rotating beam. Recovery to a nearly normal locomotor pattern was observed thereafter with a time delay comparable to that found in other behavioral studies dealing with the vestibular compensation process in the cat.