Background: Patients with bilateral vestibular hypofunction (BVH) frequently presented with dysequilibrium, dizziness and oscillopsia, leading to increased risk for fall. The mainstream for treatment of vestibular hypofunction remains to be vestibular rehabilitation, yet the effects can be limited in certain cases. Through the application of minimal amount of electrical stimulation, galvanic stimulation can induce polarization in the vestibular nerve, stimulating the saccule, utricle and semicircular canals within the vestibular apparatus. Galvanic stimulation has also been proven to activate cerebral cortex regions such as parieto-insular vestibular cortex (PIVC) and temporal-parietal junction area. It has been documented that vestibular stimulation with stochastic resonance could improve quiet stance stability in patients with vestibular hypofunction. The 3 dimensional effects of dynamic walking as well as the change of vestibular ocular reflex during stochastic resonance vestibular stimulation have never been discussed. Purposes: This 3-year project aims to investigate the effects of vestibular stimulation in VOR, static and dynamic stability, activation/connectivity of cerebral cortex and mechanisms of neuronal changes. Methods: First year the motion analysis and ICS head impulse video goggles were used to observe walking stability and eye movements in 30 healthy and 30 patients with BVH. In the second year, stochastic resonance vestibular stimulation will be applied to 30 healthy and 30 BVH individuals respectively. Using functional MRI, the changes of activated/deactivated areas in the cerebral cortex during stochastic resonance vestibular stimulation will be observed in both groups. In the third year, 60 BVH patients will be randomized into either sham or real vestibular stimulation group. Both groups will receive 3 times per week for 4 weeks of vestibular rehabilitation with exactly the same exercise protocols. SIRT1 related anti-aging genes will be analyzed through blood samples. Expected achievements: Combining safe stochastic resonance vestibular stimulation and exercises in this 3-year project, the neuroprotective mechanisms of vestibular exercises will be elucidated. The optimal strategy for vestibular rehabilitation can thus be established.

Inclusion Criteria:

• vestibular insufficiency

Exclusion Criteria:

• 1. chronic diseases that may compromise vestibular function(eg. benign paroxysmal positional vertigo, post-traumatic vertigo, degenerative neural diseases, Whiplash injury), and patients with intracranial metal inplants or history of seizure
• 2. Patients with difficulty ambulation
• 3. Patients with cognitive function