Zeng Fan-Gang
Departments of Anatomy and Neurobiology, Biomedical Engineering, Cognitive Sciences, and Otolaryngology - Head and Neck Surgery, Center for Hearing Research, University of California Irvine.
Curr Opin Physiol. 2020 Dec;18:123-129. doi: 10.1016/j.cophys.2020.10.009. Epub 2020 Nov 13.
Tinnitus is a phantom auditory sensation in the absence of external sounds, while hyperacusis is an atypical sensitivity to external sounds that leads them to be perceived as abnormally loud or even painful. Both conditions may reflect the brain's over-compensation for reduced input from the ear. The present work differentiates between two compensation models: The additive central noise compensates for hearing loss and is likely to generate tinnitus, whereas the multiplicative central gain compensates for hidden hearing loss and is likely to generate hyperacusis. Importantly, both models predict increased variance in central representations of sounds, especially a nonlinear increase in variance by the central gain. The increased central variance limits the amount of central compensation and reduces temporal synchrony, which can explain the insufficient central gain reported in the literature. Future studies need to collect trial-by-trial firing variance data so that the present variance-based model can be falsified.
耳鸣是在没有外部声音时出现的幻听，而听觉过敏是对外界声音的一种非典型敏感，导致这些声音被感知为异常响亮甚至疼痛。这两种情况都可能反映出大脑对来自耳朵的输入减少的过度补偿。目前的研究区分了两种补偿模型：加法性中枢噪声补偿听力损失，可能会产生耳鸣，而乘法性中枢增益补偿隐性听力损失，可能会产生听觉过敏。重要的是，这两种模型都预测声音的中枢表征中的方差会增加，特别是中枢增益会导致方差呈非线性增加。中枢方差的增加限制了中枢补偿的量并减少了时间同步性，这可以解释文献中报道的中枢增益不足的情况。未来的研究需要收集逐次试验的放电方差数据，以便能够证伪目前基于方差的模型。
