Departments of Otolaryngology Head and Neck Surgery and Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, USA.
J Vestib Res. 2019;29(2-3):89-96. doi: 10.3233/VES-190651.
Vestibular prostheses emulate normal vestibular function by electrically stimulating the semicircular canals using pulse frequency modulation (PFM). Spontaneous activity at the vestibular nerve may limit the dynamic range elicited by PFM. One proposed solution is the co-application of ionic direct current (iDC) to inhibit this spontaneous activity.
We aimed to test the hypothesis that a tonic iDC baseline delivered in conjunction with PFM to the vestibular semicircular canals could improve the dynamic range of evoked eye responses.
Gentamicin-treated chinchillas were implanted with microcatheter electrodes in the vestibular semicircular canals through which pulsatile and iDC current was delivered. PFM was used to modulate vestibulo-ocular reflex (VOR) once it was adapted to a preset iDC and pulse-frequency baseline. Responses to stimulation were assessed by recording the evoked VOR eye direction and velocity.
PFM produced VOR responses aligned to the stimulated canal. Introduction of an iDC baseline lead to a small but statistically significant increase in eye response velocity, without influencing the direction of eye rotation.
Tonic iDC baselines increase the dynamic range of encoding head velocity evoked by pulsatile stimulation, potentially via the inhibition of spontaneous activity in the vestibular nerve.
前庭假体通过使用脉冲频率调制 (PFM) 电刺激半规管来模拟正常的前庭功能。前庭神经的自发活动可能会限制 PFM 诱发的动态范围。一种提出的解决方案是同时应用离子直流电 (iDC) 以抑制这种自发活动。
我们旨在检验以下假设，即在向前庭半规管施加 PFM 的同时施加持续 iDC 基线可以改善诱发眼反应的动态范围。
经庆大霉素处理的南美栗鼠通过微导管电极植入前庭半规管，通过该电极施加脉动和 iDC 电流。一旦 PFM 适应预设的 iDC 和脉冲频率基线，就用于调制前庭眼反射 (VOR)。通过记录诱发的 VOR 眼方向和速度来评估刺激反应。
PFM 产生与刺激管对齐的 VOR 反应。引入 iDC 基线会导致眼反应速度略有但统计学上显著增加，而不影响眼旋转的方向。
持续 iDC 基线增加了脉动刺激诱发的头部速度编码的动态范围，可能是通过抑制前庭神经中的自发活动。
