IntroductionThe mechanisms underlying tinnitus perception are still under research. One of the proposed hypotheses involves an alteration in top-down processing of auditory activity. Low-frequency oscillations in the delta and theta bands have been recently described in brain and cochlear infrasonic signals during selective attention paradigms in normal hearing controls. Here, we propose that the top-down oscillatory activity observed in brain and cochlear signals during auditory and visual selective attention in normal subjects, is altered in tinnitus patients, reflecting an abnormal functioning of the corticofugal pathways that connect brain circuits with the cochlear receptor.MethodsTo test this hypothesis, we used a behavioral task that alternates between auditory and visual top-down attention while we simultaneously measured electroencephalogram (EEG) and distortion-product otoacoustic emissions (DPOAE) signals in 14 tinnitus and 14 control subjects.ResultsWe found oscillatory activity in the delta and theta bands in cortical and cochlear channels in control and tinnitus patients. There were significant decreases in the DPOAE oscillatory amplitude during the visual attention period as compared to the auditory attention period in tinnitus and control groups. We did not find significant differences when using a between-subjects statistical approach comparing tinnitus and control groups. On the other hand, we found a significant cluster in the delta band in tinnitus when using within-group statistics to compare the difference between auditory and visual DPOAE oscillatory power.ConclusionThese results confirm the presence of top-down infrasonic low-frequency cochlear oscillatory activity in the delta and theta bands in tinnitus patients, showing that the corticofugal suppression of cochlear oscillations during visual and auditory attention in tinnitus patients is preserved.

中文翻译：

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听觉和视觉注意力期间耳蜗受体的皮质振荡调节在耳鸣中得以保留

简介耳鸣感知的机制仍在研究中。提出的假设之一涉及听觉活动自上而下处理的改变。最近，在正常听力控制的选择性注意范式中，大脑和耳蜗次声信号中描述了 δ 和 θ 频段的低频振荡。在这里，我们提出，在正常受试者的听觉和视觉选择性注意过程中，在大脑和耳蜗信号中观察到的自上而下的振荡活动在耳鸣患者中发生了改变，反映了连接大脑回路与耳蜗受体的皮质通路的功能异常。方法为了检验这一假设，我们使用了一项行为任务，该任务在听觉和视觉自上而下的注意力之间交替，同时测量 14 名耳鸣受试者和 14 名对照受试者的脑电图 (EEG) 和失真产物耳声发射 (DPOAE) 信号。结果我们发现了振荡活动对照组和耳鸣患者的皮质和耳蜗通道的 δ 和 θ 波段。与耳鸣组和对照组的听觉注意期相比，视觉注意期的 DPOAE 振荡幅度显着降低。当使用受试者间统计方法比较耳鸣和对照组时，我们没有发现显着差异。另一方面，当使用组内统计数据比较听觉和视觉 DPOAE 振荡功率之间的差异时，我们发现耳鸣的 delta 频段存在显着的簇。结论这些结果证实了自上而下的次声低频耳蜗振荡活动的存在在耳鸣患者的 delta 和 theta 频带中，表明耳鸣患者在视觉和听觉注意力过程中耳蜗振荡的皮质抑制得以保留。