Strimbu C Elliott, Olson Elizabeth S
Columbia University Department of Otolaryngology Head and Neck Surgery, New York, New York.
Columbia University Department of Otolaryngology Head and Neck Surgery, New York, New York; Columbia University Department of Biomedical Engineering, New York, New York.
Biophys J. 2025 Jan 21;124(2):297-315. doi: 10.1016/j.bpj.2024.12.004. Epub 2024 Dec 4.
The cochlea's mechanical response to sound stimulation is nonlinear, likely due to saturation of the mechanoelectric transduction current that is part of an electromechanical feedback loop. The ability of a second tone or tones to reduce the response to a probe tone is one manifestation of nonlinearity, termed suppression. Using optical coherence tomography to measure motion within the organ of Corti, regional motion variations have been observed. Here, we report on the suppression that occurs within the organ of Corti when a high-sound-level, low-frequency suppressor tone was delivered along with a sweep of discreet single tones. Responses were measured in the base of the gerbil cochlea at two best frequency locations, with two different directions of observation relative to the sensory tissue's anatomical axes. Suppression extended over a wide frequency range in the outer hair cell region, whereas it was typically limited to the best frequency peak in the reticular lamina region and at the basilar membrane. Aspects of the observed suppression were consistent with the effect of a saturating nonlinearity. Recent measurements have noted the three-dimensional nature of organ of Corti motion. The effects of suppression observed here could be due to a combination of reduced motion amplitude and altered vibration axis.
耳蜗对声音刺激的机械反应是非线性的，这可能是由于机电转换电流饱和所致，而该电流是机电反馈回路的一部分。第二个或多个音调降低对探测音反应的能力是非线性的一种表现，称为抑制。利用光学相干断层扫描技术测量柯蒂氏器内的运动，已观察到区域运动变化。在此，我们报告当一个高声级、低频抑制音与一系列离散单音一起呈现时，柯蒂氏器内发生的抑制情况。在沙鼠耳蜗底部的两个最佳频率位置进行了反应测量，相对于感觉组织的解剖轴有两个不同的观察方向。抑制在外毛细胞区域的较宽频率范围内都有，而在网状板区域和基底膜处通常仅限于最佳频率峰值。观察到的抑制方面与饱和非线性效应一致。最近的测量已经注意到柯蒂氏器运动的三维性质。这里观察到的抑制效应可能是运动幅度减小和振动轴改变共同作用的结果。
