| Description |
Current cochlear implant devices provide limited hearing ability to the deaf through electrical stimulation of the auditory nerve. Recent studies have shown that pulsed infrared (IR) radiation can also be used to stimulate the inner ear neurons and has the potential to be used in prostheses to help restore auditory and vestibular sensations. IR has the advantage of focal stimulation, which may provide improved fidelity over electrical stimuli. Sensitivity of neurons to pulsed IR is primarily due to rapid transient increases in temperature, which modulate the function of ion channels and other key proteins. In the present work, we examined the temperature sensitivity of semicircular canal afferent nerve discharge rate in a common vestibular model, the oyster toadfish, opsanus tau. We found that the temperature sensitivity between individual afferent neurons varied, but that the data could be separated into two groups: those showing increasing discharge rate with increasing temperature and those showing decreasing rate with increasing temperature. Responses indicate the presence of both excitatory and inhibitory neural mechanisms responding to pulsatile changes in temperature. We hypothesize that convergence of excitatory glutamatergic and inhibitory GABAergic neurotransmission may be responsible for the temperature dependence of spontaneous discharge rates and sensitivity to angular motion stimuli in the semicircular canals. |
