Department of Electrical, Electronic and Computer Engineering, University of Pretoria, Pretoria, South Africa.
Hear Res. 2010 Oct 1;269(1-2):12-22. doi: 10.1016/j.heares.2010.08.004. Epub 2010 Aug 12.
The ability of a human auditory nerve fibre computational model to predict threshold differences for biphasic, pseudomonophasic and alternating monophasic waveforms was investigated. The effect of increasing the interphase gap, interpulse interval and pulse rate on thresholds was also simulated. Simulations were performed for both anodic-first and cathodic-first stimuli. Results indicated that the model correctly predicted threshold reductions for pseudomonophasic compared to biphasic waveforms, although reduction for alternating monophasic waveforms was underestimated. Threshold reductions were more pronounced for cathodic-first stimuli compared to anodic-first stimuli. Reversal of the phases in pseudomonophasic stimuli suggested a threshold reduction for anodic-first stimuli, but a threshold increase in cathodic-first stimuli. Inclusion of the persistent sodium and slow potassium currents in the model resulted in a reasonably accurate prediction of the non-monotonic threshold behaviour for pulse rates higher than 1000 pps. However, the model did not correctly predict the threshold changes observed for low pulse rate biphasic and alternating monophasic waveforms. It was suggested that these results could in part be explained by the difference in the refractory periods between real and simulated auditory nerve fibres, but also by the lack of representation of stochasticity observed in real auditory nerve fibres in our auditory nerve model.
研究了一种人类听觉神经纤维计算模型预测双相、伪单相和交替单相波形阈值差异的能力。还模拟了增加相间间隙、脉冲间隔和脉冲率对阈值的影响。对阳极优先和阴极优先刺激都进行了模拟。结果表明，该模型正确预测了伪单相相对于双相波形的阈值降低，尽管对交替单相波形的降低程度估计不足。与阳极优先刺激相比，阴极优先刺激的阈值降低更为明显。伪单相刺激中相位的反转表明，对于阳极优先刺激，阈值降低，但对于阴极优先刺激，阈值增加。在模型中包含持续钠电流和慢钾电流，可合理准确地预测高于 1000 pps 的脉冲率下的非单调阈值行为。然而，该模型并未正确预测在低脉冲率双相和交替单相波形中观察到的阈值变化。研究表明，这些结果部分可以用真实和模拟听觉神经纤维之间的不应期差异来解释，但也可以用我们的听觉神经模型中缺乏对真实听觉神经纤维中观察到的随机性的表示来解释。
