Ramirez Rey Rene, Kopell Brian Harris, Butson Christopher R, Gaggl Wolfgang, Friedland David R, Baillet Sylvain
Medical College of Wisconsin, Milwaukee, WI 80305, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2009;2009:1940-4. doi: 10.1109/IEMBS.2009.5333457.
Electrical cortical stimulation (CS) of the auditory cortices has been shown to reduce the severity of debilitating tinnitus in some patients. In this study, we performed MEG source imaging of spontaneous brain activity during concurrent CS of the left secondary auditory cortex of a volunteer suffering from right unilateral tinnitus. CS produced MEG artifacts which were successfully sorted and removed using a combination of sensor and source level signal separation and classification techniques. This contribution provides the first proof of concept reporting on analysis of MEG data with concurrent CS. Effects of CS on ongoing brain activity were revealed at the MEG sensor and source levels and indicate CS significantly reduced ongoing brain activity in the lower frequency range (<40Hz), and emphasized its higher (>40Hz), gamma range components. Further, our results show that CS increased the spectral correlation across multiple frequency bands in the low and high gamma ranges, and between the alpha and beta bands of the MEG. Finally, MEG sources localized in the auditory cortices and nearby regions exhibited abnormal spectral activity that was suppressed by CS. These results provide promising evidence in favor of the Thalamocortical Dysrhytmia (TCD) hypothesis of tinnitus, and suggest that CS may prove to be an effective treatment of tinnitus when targeted to brain regions exhibiting abnormal spontaneous activity.
听觉皮层的电刺激（CS）已被证明可减轻一些患者使人衰弱的耳鸣严重程度。在本研究中，我们对一名患有右侧单侧耳鸣的志愿者的左侧次级听觉皮层进行同步CS时的自发脑活动进行了脑磁图（MEG）源成像。CS产生了MEG伪迹，通过传感器和源水平信号分离与分类技术的组合成功地对其进行了分类和去除。本研究首次提供了关于同步CS时MEG数据分析的概念验证报告。在MEG传感器和源水平上揭示了CS对持续脑活动的影响，表明CS显著降低了低频范围（<40Hz）内的持续脑活动，并增强了其较高频率（>40Hz）的伽马范围成分。此外，我们的结果表明，CS增加了低伽马和高伽马范围内多个频段之间以及MEG的阿尔法和贝塔频段之间的频谱相关性。最后，位于听觉皮层和附近区域的MEG源表现出异常的频谱活动，该活动被CS抑制。这些结果为耳鸣的丘脑皮层节律紊乱（TCD）假说提供了有力证据，并表明当针对表现出异常自发活动的脑区时，CS可能被证明是一种有效的耳鸣治疗方法。
