Thai-Van Hung, Micheyl Christophe, Norena Arnaud, Veuillet Evelyne, Gabriel Damien, Collet Lionel
Université de Lyon, Lyon F-69003, France.
Hear Res. 2007 Nov;233(1-2):14-22. doi: 10.1016/j.heares.2007.06.003. Epub 2007 Jun 9.
Cochlear damages have been shown to induce changes in tonotopic maps in the central auditory system of animals; neurons deprived from peripheral inputs start to respond to stimuli with frequencies close to the cutoff frequency (Fc) or "edge" of the hearing loss, which then become over-represented at the neural level. Here, we review findings, which reveal a possible psychophysical correlate of such central over-representation in human listeners with sensorineural hearing loss. These findings concur to demonstrate a local improvement in difference limens for frequency (DLFs) at or near Fc. This effect has now been observed in several studies and subjects with varied audiometric characteristics, including high- and low-frequency, and symmetric and asymmetric hearing losses. The presence of cochlear dead region or a steeply sloping hearing loss appear as a necessary condition for its occurrence. The effect cannot be explained simply by more prominent loudness cues or spontaneous otoacoustic emissions (SOAEs) near the audiogram edge. Overall, the data are consistent with local changes in pitch discrimination performance near the hearing-loss cutoff frequency being a result of the neural over-representation of that frequency region in the central auditory system. Further work is needed to confirm this hypothesis, and investigate other possible perceptual correlates of injury-related cortical plasticity in both humans and animals.
研究表明，耳蜗损伤会引起动物中枢听觉系统音调拓扑图的变化；失去外周输入的神经元开始对频率接近听力损失截止频率（Fc）或“边缘”的刺激产生反应，这些频率随后在神经层面上过度代表。在这里，我们回顾了一些研究结果，这些结果揭示了在感音神经性听力损失的人类听众中，这种中枢过度代表可能存在的心理物理学关联。这些结果一致表明，在Fc或其附近，频率辨别阈限（DLFs）有局部改善。现在，在几项研究以及具有不同听力图特征（包括高频和低频、对称和不对称听力损失）的受试者中都观察到了这种效应。耳蜗死区的存在或陡峭的听力损失似乎是其发生的必要条件。这种效应不能简单地用听力图边缘附近更突出的响度线索或自发性耳声发射（SOAEs）来解释。总体而言，数据表明，听力损失截止频率附近音高辨别性能的局部变化是该频率区域在中枢听觉系统中神经过度代表的结果。需要进一步的研究来证实这一假设，并研究人类和动物中与损伤相关的皮质可塑性的其他可能的感知关联。
