Chen L, Trautwein P G, Powers N, Salvi R J
Department of Communicative Disorders and Sciences, State University of New York at Buffalo 14214, USA.
J Acoust Soc Am. 1997 Oct;102(4):2245-54. doi: 10.1121/1.419598.
The purpose of the present study was to examine the effects of acoustic trauma and hair cell loss and regeneration on the two-tone rate suppression (TTRS) boundaries of cochlear ganglion neurons in chickens. Chickens were exposed for 48 hours to a 525-Hz, 120-dB SPL tone which destroyed the hair cells and tectorial membrane in a crescent-shaped patch along the abneural side of the basilar papilla. Afterwards, TTRS boundaries were recorded from cochlear ganglion neurons at 0-1, 5, 14, and 28 days postexposure. Acoustic trauma reduced the percentage of neurons with TTRS boundaries below CF (TTRSb) (52.6% to 8.2%) and above CF (TTRSa) (88.4% to 46.6%). In addition, the exposure reduced TTRS boundary slopes, elevated best suppression threshold (BST), and increased the frequency separation between the tips of the TTRS boundaries and CF. All the TTRS measures started to recover by 5 days postexposure and by 14 days and 28 days postexposure, most measures had recovered to normal levels. However, the BST, TTRS slopes, and the frequency separation of TTRSb boundaries from CF were still slightly abnormal near the exposure frequency. In addition, the percentage of neurons with TTRS below CF was reduced significantly. The partial recovery of TTRS boundaries is presumably due to the regeneration of hair cells and the lower honeycomb layer of the tectorial membrane. The residual TTRS deficits observed 28 days postexposure were most closely associated with the missing upper fibrous layer of the tectorial membrane.
本研究的目的是考察声损伤以及毛细胞缺失和再生对鸡耳蜗神经节神经元双音速率抑制（TTRS）边界的影响。将鸡暴露于525赫兹、120分贝声压级的纯音下48小时，该纯音破坏了沿基底乳头神经外侧面呈新月形区域的毛细胞和盖膜。之后，在暴露后0 - 1天、5天、14天和28天记录耳蜗神经节神经元的TTRS边界。声损伤降低了TTRS边界低于特征频率（CF）（TTRSb）的神经元百分比（从52.6%降至8.2%）以及高于CF（TTRSa）的神经元百分比（从88.4%降至46.6%）。此外，暴露降低了TTRS边界斜率，提高了最佳抑制阈值（BST），并增加了TTRS边界顶端与CF之间的频率间隔。所有TTRS指标在暴露后5天开始恢复，到暴露后14天和28天，大多数指标已恢复到正常水平。然而，在暴露频率附近，BST、TTRS斜率以及TTRSb边界与CF之间的频率间隔仍略有异常。此外，TTRS低于CF的神经元百分比显著降低。TTRS边界的部分恢复可能是由于毛细胞和盖膜下部蜂窝层的再生。暴露后28天观察到的TTRS缺陷残留与盖膜缺失的上部纤维层密切相关。
