Stein Alwina, Engell Alva, Lau Pia, Wunderlich Robert, Junghoefer Markus, Wollbrink Andreas, Bruchmann Maximilian, Rudack Claudia, Pantev Christo
Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Muenster, Germany.
Department of Otolaryngology, University Hospital, Muenster, Germany.
PLoS One. 2015 May 7;10(5):e0126494. doi: 10.1371/journal.pone.0126494. eCollection 2015.
Chronic tinnitus seems to be caused by reduced inhibition among frequency selective neurons in the auditory cortex. One possibility to reduce tinnitus perception is to induce inhibition onto over-activated neurons representing the tinnitus frequency via tailor-made notched music (TMNM). Since lateral inhibition is modifiable by spectral energy contrasts, the question arises if the effects of inhibition-induced plasticity can be enhanced by introducing increased spectral energy contrasts (ISEC) in TMNM. Eighteen participants suffering from chronic tonal tinnitus, pseudo randomly assigned to either a classical TMNM or an ISEC-TMNM group, listened to notched music for three hours on three consecutive days. The music was filtered for both groups by introducing a notch filter centered at the individual tinnitus frequency. For the ISEC-TMNM group a frequency bandwidth of 3/8 octaves on each side of the notch was amplified, additionally, by about 20 dB. Before and after each music exposure, participants rated their subjectively perceived tinnitus loudness on a visual analog scale. During the magnetoencephalographic recordings, participants were stimulated with either a reference tone of 500 Hz or a test tone with a carrier frequency representing the individual tinnitus pitch. Perceived tinnitus loudness was significantly reduced after TMNM exposure, though TMNM type did not influence the loudness ratings. Tinnitus related neural activity in the N1m time window and in the so called tinnitus network comprising temporal, parietal and frontal regions was reduced after TMNM exposure. The ISEC-TMNM group revealed even enhanced inhibition-induced plasticity in a temporal and a frontal cortical area. Overall, inhibition of tinnitus related neural activity could be strengthened in people affected with tinnitus by increasing spectral energy contrast in TMNM, confirming the concepts of inhibition-induced plasticity via TMNM and spectral energy contrasts.
慢性耳鸣似乎是由听觉皮层中频率选择性神经元之间的抑制作用减弱所引起的。降低耳鸣感知的一种可能性是通过特制的带陷波音乐（TMNM）对代表耳鸣频率的过度激活神经元施加抑制作用。由于侧向抑制可通过频谱能量对比进行调节，因此问题在于，在TMNM中引入增加的频谱能量对比（ISEC）是否能够增强抑制诱导可塑性的效果。18名患有慢性音调性耳鸣的参与者被伪随机分配到经典TMNM组或ISEC-TMNM组，连续三天每天聆听三小时的带陷波音乐。两组的音乐均通过引入以个体耳鸣频率为中心的陷波滤波器进行滤波。对于ISEC-TMNM组，陷波两侧各3/8倍频程的频率带宽额外放大了约20 dB。在每次音乐暴露前后，参与者通过视觉模拟量表对主观感知的耳鸣响度进行评分。在脑磁图记录过程中，参与者分别受到500 Hz的参考音或具有代表个体耳鸣音高的载波频率的测试音刺激。TMNM暴露后，感知到的耳鸣响度显著降低，尽管TMNM类型并未影响响度评分。TMNM暴露后，N1m时间窗口以及包括颞叶、顶叶和额叶区域的所谓耳鸣网络中与耳鸣相关的神经活动减少。ISEC-TMNM组在颞叶和额叶皮质区域显示出更强的抑制诱导可塑性。总体而言，通过增加TMNM中的频谱能量对比，可以增强耳鸣患者对耳鸣相关神经活动的抑制作用，这证实了通过TMNM和频谱能量对比实现抑制诱导可塑性的概念。
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