What part of the cerebellum is this: 1) To control the activity of the motor pathways (the vestibulospinal and reticulospinal tracts) concerned with regulation of the TON AND CONTRACTILITY OF THE ANTIGRAVITY MUSCLES in response to vestibular sensory signals, and is therefore largely concerned with REGULATION OF EQUILIBRIUM. 2) To regulates movements of the eyeballs during head movements to maintain stable vision.