This research will explore the physiology of the cerebellar nodulus and uvula and their role in ocular and neck muscle reflexes that control gaze. The strong vestibular and visual inputs to nodulus and uvula suggest a function in convergent processing of sensory inputs and adaptation to distrubed sensory input, and their outputs suggest a reflex control function. Physiological recordings have shown sensory convergence in other cerebellar structures, and lesion studies have implicated cerebellum investibulo-ocular reflex adaptation, which requires visual-vestibular interaction, but there have been few studies of nodulus and uvula. Neural activity in nodulus and uvula will be recorded in awake animals which are free to look about or are fixating a stationary spot. Single neuron responses will be related to visual field motion stimuli and vestibular rotation stimuli which are presented either separately or simultaneously. Stimuli will be presented in a variety of different planes or directions. Simultaneous stimuli will either convey the same information about the speed and direction of motion, or will ave various discrepancies between visual and vestibular stimulus information, including conflicts like those that elicit vestibulo-ocular refles adaptation. Lesions of nodulus and uvula will be made, and tests will be done of the vestibulo-ocular reflex, optokinetic nystagmus and after nystagmus, the cervico-ocular refles, vestibulo-collic refles, and vestibulo-ocular refles suppression before and after the lesions to examine the role of nodulus and uvula in controlling the dynamics and spatial organization of these gaze reflexes. The same reflexes will also be studied in animals that have been fitted with magnifying or reducing spectacles that produce an adaptive modification of the vestibulo-ocular refles. Animals will undergo and adaptation procedure, be tested, receive a lesion, be retested, undergo the adaptation procedure again, then be tested again. The results of the proposed experiments will give us further insight into the functions of the cerebellum in motor behavior, adaptation to disturbed sensory inputs, and recovery from neurological disorders caused by brain damage.
Showing the most recent 10 out of 19 publications
