Scinicariello Anthony P, Inglis J Timothy, Collins J J
Center for BioDynamics and Department of Biomedical Engineering, Boston University, 44 Cummington St., Boston, MA 02215, USA.
J Vestib Res. 2002;12(2-3):77-85.
Galvanic vestibular stimulation (GVS) is a technique in which small currents are delivered transcutaneously to the afferent nerve endings of the vestibular system through electrodes placed over the mastoid bones. The applied current alters the firing rates of the peripheral vestibular afferents, causing a shift in a standing subject's vestibular perception and a corresponding postural sway. Previously, we showed that in subjects who are facing forward, stochastic bipolar binaural GVS leads to coherent stochastic mediolateral postural sway. The goal of this pilot study was to extend that work and to test the hypothesis that in subjects who are facing forward, stochastic monopolar binaural GVS leads to coherent stochastic anteroposterior postural sway. Stochastic monopolar binaural GVS was applied to ten healthy young subjects. Twenty-four trials, each containing a different galvanic input stimulus from among eight different frequency ranges, were conducted on each subject. Postural sway was evaluated through analysis of the center-of-pressure (COP) displacements under each subject's feet. Spectral analysis was performed on the galvanic stimuli and the COP displacement time series to calculate the coherence spectra. Significant coherence was found between the galvanic input signal and the anteroposterior COP displacement in some of the trials (i.e., at least one) in nine of the ten subjects. In general, the coherence values were highest for the mid-range frequencies that were tested, and lowest for the low- and high-range frequencies. However, the coherence values we obtained were lower than those we previously reported for stochastic bipolar binaural GVS and mediolateral sway. These differences may be due to fundamental characteristics of the vestibular system such as lower sensitivity to symmetric changes in afferent firing dynamics, and/or differences between the biomechanics of anteroposterior and mediolateral sway.
直流电前庭刺激（GVS）是一种技术，通过放置在乳突骨上的电极经皮向前庭系统的传入神经末梢输送小电流。施加的电流会改变外周前庭传入神经的放电频率，导致站立受试者的前庭感知发生变化以及相应的姿势摆动。此前，我们表明，在面向前方的受试者中，随机双极双耳GVS会导致连贯的随机中外侧姿势摆动。这项初步研究的目的是扩展该工作，并检验以下假设：在面向前方的受试者中，随机单极双耳GVS会导致连贯的随机前后姿势摆动。对十名健康的年轻受试者施加了随机单极双耳GVS。对每个受试者进行了24次试验，每次试验包含来自八个不同频率范围中的不同电刺激输入。通过分析每个受试者脚下的压力中心（COP）位移来评估姿势摆动。对电刺激和COP位移时间序列进行频谱分析以计算相干谱。在十名受试者中的九名受试者的一些试验（即至少一次）中，发现电刺激输入信号与前后COP位移之间存在显著的相干性。一般来说，在所测试的中频范围内相干值最高，而在低频和高频范围内最低。然而，我们获得的相干值低于我们之前报道的随机双极双耳GVS和中外侧摆动的相干值。这些差异可能归因于前庭系统的基本特征，例如对传入放电动态的对称变化敏感性较低，和/或前后摆动与中外侧摆动的生物力学差异。
