Auditory Group, Institute of Neuroscience, Newcastle University Medical School, Framlington Place, Newcastle Upon Tyne NE2 4HH, UK.
Brain. 2012 Oct;135(Pt 10):3089-100. doi: 10.1093/brain/aws220. Epub 2012 Sep 13.
This study used magnetoencephalography to record oscillatory activity in a group of 17 patients with chronic tinnitus. Two methods, residual inhibition and residual excitation, were used to bring about transient changes in spontaneous tinnitus intensity in order to measure dynamic tinnitus correlates in individual patients. In residual inhibition, a positive correlation was seen between tinnitus intensity and both delta/theta (6/14 patients) and gamma band (8/14 patients) oscillations in auditory cortex, suggesting an increased thalamocortical input and cortical gamma response, respectively, associated with higher tinnitus states. Conversely, 4/4 patients exhibiting residual excitation demonstrated an inverse correlation between perceived tinnitus intensity and auditory cortex gamma oscillations (with no delta/theta changes) that cannot be explained by existing models. Significant oscillatory power changes were also identified in a variety of cortical regions, most commonly midline lobar regions in the default mode network, cerebellum, insula and anterior temporal lobe. These were highly variable across patients in terms of areas and frequency bands involved, and in direction of power change. We suggest a model based on a local circuit function of cortical gamma-band oscillations as a process of mutual inhibition that might suppress abnormal cortical activity in tinnitus. The work implicates auditory cortex gamma-band oscillations as a fundamental intrinsic mechanism for attenuating phantom auditory perception.
本研究使用脑磁图记录了 17 名慢性耳鸣患者的脑振荡活动。采用残留抑制和残留兴奋两种方法使自发性耳鸣强度发生短暂变化，以测量个体患者的动态耳鸣相关性。在残留抑制中，耳鸣强度与听觉皮层中的 delta/theta（6/14 名患者）和 gamma 波段（8/14 名患者）振荡之间呈正相关，分别提示与更高的耳鸣状态相关的丘脑皮质输入增加和皮质 gamma 反应增加。相反，4/4 名表现出残留兴奋的患者表现出感知的耳鸣强度与听觉皮层 gamma 振荡之间的反相关（无 delta/theta 变化），这不能用现有模型解释。在各种皮质区域中也鉴定出显著的振荡功率变化，最常见于默认模式网络的中线叶区、小脑、脑岛和前颞叶。这些在涉及的区域和频带以及功率变化的方向方面在患者之间具有高度可变性。我们提出了一种基于皮质 gamma 波段振荡的局部回路功能的模型，作为一种可能抑制耳鸣中异常皮质活动的相互抑制过程。这项工作暗示听觉皮层 gamma 波段振荡是减弱幻听感知的基本内在机制。
