During оculоmоtor аnd vestibulаr testing in room light for а patient with "dizziness", a physical therapist observes the following: No spontaneous or gaze-evoked nystagmus noted Smooth pursuit demonstrates catch-up saccades during testing Dysmetria noted during saccades testing Normal head impulse / head thrust test Based on this information, the patient's pathology is MOST consistent with which of the following