Ueberfuhr Margarete Anna, Braun Amalia, Wiegrebe Lutz, Grothe Benedikt, Drexl Markus
German Center for Vertigo and Balance Disorders, University Hospital Munich, Ludwig-Maximilians-Universität München, Munich, Germany; Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität München, Martinsried, Germany.
Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Martinsried, Germany.
Hear Res. 2017 Jul;350:235-243. doi: 10.1016/j.heares.2017.03.008. Epub 2017 Mar 18.
Transcutaneous, electrical stimulation with electrodes placed on the mastoid processes represents a specific way to elicit vestibular reflexes in humans without active or passive subject movements, for which the term galvanic vestibular stimulation was coined. It has been suggested that galvanic vestibular stimulation mainly affects the vestibular periphery, but whether vestibular hair cells, vestibular afferents, or a combination of both are excited, is still a matter of debate. Galvanic vestibular stimulation has been in use since the late 18th century, but despite the long-known and well-documented effects on the vestibular system, reports of the effect of electrical stimulation on the adjacent cochlea or the ascending auditory pathway are surprisingly sparse. The present study examines the effect of transcutaneous, electrical stimulation of the human auditory periphery employing evoked and spontaneous otoacoustic emissions and several psychoacoustic measures. In particular, level growth functions of distortion product otoacoustic emissions were recorded during electrical stimulation with alternating currents (2 Hz, 1-4 mA in 1 mA-steps). In addition, the level and frequency of spontaneous otoacoustic emissions were followed before, during, and after electrical stimulation (2 Hz, 1-4 mA). To explore the effect of electrical stimulation on the retrocochlear level (i.e. on the ascending auditory pathway beyond the cochlea), psychoacoustic experiments were carried out. Specifically, participants indicated whether electrical stimulation (4 Hz, 2 and 3 mA) induced amplitude modulations of the perception of a pure tone, and of auditory illusions after presentation of either an intense, low-frequency sound (Bounce tinnitus) or a faint band-stop noise (Zwicker tone). These three psychoacoustic measures revealed significant perceived amplitude modulations during electrical stimulation in the majority of participants. However, no significant changes of evoked and spontaneous otoacoustic emissions could be detected during electrical stimulation relative to recordings without electrical stimulation. The present findings show that cochlear function, as assessed with spontaneous and evoked otoacoustic emissions, is not affected by transcutaneous electrical stimulation, at the currents used in this study. Psychoacoustic measures like pure tone perception, but also auditory illusions, are affected by electrical stimulation. This indicates that activity of the retrocochlear ascending auditory pathway is modulated during transcutaneous electrical stimulation.
将电极置于乳突上进行经皮电刺激，是在人体不进行主动或被动运动的情况下诱发前庭反射的一种特定方式，“电刺激前庭”这一术语由此而来。有人认为电刺激前庭主要影响前庭外周，但究竟是前庭毛细胞、前庭传入神经，还是两者共同被激活，仍存在争议。自18世纪末以来就一直使用电刺激前庭，但尽管其对前庭系统的影响早已为人所知且有充分记录，但关于电刺激对相邻耳蜗或上行听觉通路影响的报道却出奇地少。本研究采用诱发耳声发射和自发耳声发射以及几种心理声学测量方法，来研究经皮电刺激人体听觉外周的效果。具体而言，在使用交流电（2赫兹，以1毫安步长从1至4毫安）进行电刺激期间，记录畸变产物耳声发射的电平增长函数。此外，在电刺激前、刺激期间和刺激后（2赫兹，1至4毫安）跟踪自发耳声发射的电平及频率。为探究电刺激对耳蜗后水平（即耳蜗以外的上行听觉通路）的影响，进行了心理声学实验。具体来说，参与者需指出电刺激（4赫兹，2和3毫安）是否会诱发纯音感知的幅度调制，以及在呈现强烈低频声音（弹跳性耳鸣）或微弱带阻噪声（齐克勒音）后是否会诱发听觉错觉。这三种心理声学测量方法显示，在大多数参与者中，电刺激期间可察觉到明显的幅度调制。然而，与无电刺激记录相比，电刺激期间未检测到诱发耳声发射和自发耳声发射有显著变化。本研究结果表明，在本研究使用的电流下，经皮电刺激不会影响用自发耳声发射和诱发耳声发射评估的耳蜗功能。像纯音感知这样的心理声学测量方法，以及听觉错觉，都会受到电刺激的影响。这表明在经皮电刺激期间，耳蜗后上行听觉通路的活动受到了调制。
