Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK; Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK.
Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK; Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK.
Neurosci Lett. 2021 Mar 16;747:135705. doi: 10.1016/j.neulet.2021.135705. Epub 2021 Feb 3.
Tinnitus has similarities to chronic neuropathic pain where there are changes in the firing rate of different types of afferent neurons. We postulated that one possible cause of tinnitus is a change in the distribution of spontaneous firing rates in at least one type of afferent auditory nerve fibre in anaesthetised guinea pigs. In control animals there was a bimodal distribution of spontaneous rates, but the position of the second mode was different depending upon whether the fibres responded best to high (> 4 kHz) or low (≤4 kHz) frequency tonal stimulation. The simplest and most reliable way of inducing tinnitus in experimental animals is to administer a high dose of sodium salicylate. The distribution of the spontaneous firing rates was different when salicylate (350 mg/kg) was administered, even when the sample was matched for the distribution of characteristic frequencies in the control population. The proportion of medium spontaneous rate fibres (MSR, 1≤ spikes/s ≤20) increased while the proportion of the highest, high spontaneous firing rate fibres (HSR, > 80 spikes/s) decreased following salicylate. The median rate fell from 64.7 spikes/s (control) to 35.4 spikes/s (salicylate); a highly significant change (Kruskal-Wallis test p < 0.001). When the changes were compared with various models of statistical probability, the most accurate model was one where most HSR fibres decreased their firing rate by 32 spikes/s. Thus, we have shown a reduction in the firing rate of HSR fibres that may be related to tinnitus.
耳鸣与慢性神经性疼痛相似，其中存在传入神经元的不同类型的放电率的变化。我们推测，耳鸣的一个可能原因是在麻醉豚鼠的至少一种传入听觉神经纤维中自发性放电率分布的改变。在对照动物中，自发率呈双峰分布，但第二个模式的位置取决于纤维对高频（>4 kHz）或低频（≤4 kHz）音调刺激的最佳反应。在实验动物中最简便可靠地诱发耳鸣的方法是给予大剂量的水杨酸钠。即使将样本与对照群体中的特征频率分布相匹配，水杨酸盐（350 mg/kg）给药后自发率的分布也不同。中等自发率纤维（MSR，1≤ spikes/s ≤20）的比例增加，而最高的高自发性放电率纤维（HSR，> 80 spikes/s）的比例在水杨酸盐给药后减少。中位数从 64.7 spikes/s（对照）下降到 35.4 spikes/s（水杨酸盐）；这是一个非常显著的变化（Kruskal-Wallis 检验 p < 0.001）。当将这些变化与各种统计概率模型进行比较时，最准确的模型是大多数 HSR 纤维的放电率降低 32 spikes/s。因此，我们已经显示出 HSR 纤维的放电率降低，这可能与耳鸣有关。
