Abstract
Vestibular dysfunction and balance disorders significantly impact the quality of life of patients. To assist patients with bilateral vestibulopathies and in cases where current forms of treatment are not effective, there is a need to develop neural prosthesis. In some cases, although the vestibular system could not sense the input balance signals, a significant numbers of nerve cells remain to respond to electrical stimulation(Jensen 1983). So developing a electrode based vestibular prosthesis becomes a practical solution. Vestibular prosthesis has been researched over the past decades, and vestibular function restoration is partly realized in animals such as chinchilla(Santina, Migliaccio et al. 2007) and rhesus monkey (Phillips, Bierer et al. 2011). However, Several limitations accompanied with current electrical stimulation method limit the prosthesis from becoming a practical treatment. The spatial selectivity is one of the major limitations. The electrical current spreads out of the target region and often causes unwanted response from other organs (Santina, Migliaccio et al. 2005, Phillips, Bierer et al. 2011). Also in some cases, the electrical current may stimulate other nerves such as facial nerve (Phillips, Bierer et al. 2011). Finally, because the electrode needs to be in contact with the stimulating target, there is possibility to cause tissue damage. Pulsed infrared radiation (IR) has recently been utilized for neural stimulation (Izzo, Walsh et al. 2007, Rajguru, Richter et al. 2011, Richter and Tan 2014). Long-wavelength (1800~2000 μm), pulsed IR laser radiation, evokes responses in rat sciatic nerve(Wells, Kao et al. 2005), auditory nerve (Izzo, Richter et al. 2006), quail embryo hearts(Jenkins, Duke et al. 2010), vestibular hair cells(Rajguru, Richter et al. 2011) and vestibular nerve(Harris, Bierer et al. 2009). There are several potential advantages of IR: the IR delivery component does not need to be intact with the target, which avoids physical damage to the tissue. Also, IR beam can be focused and has been shown to have better spatial selectivity(Richter, Rajguru et al. 2011, Richter and Tan 2014). In the present proposal, we aim to design a vestibular prosthesis based on IR stimulation. We plan to use fiber optic to deliver IR pulses to stimulate rat vestibular system and record vestibular-Ocular-Reflex (VOR) as reference to validate the efficacy of IR stimulation. We will also stud y various parameters of IR stimulation to determine its safety.