Chen L, Trautwein P G, Shero M, Salvi R J
Hearing Research Laboratories, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, NY 14214, USA.
Hear Res. 1996 Sep 1;98(1-2):152-64. doi: 10.1016/0378-5955(96)00086-x.
Adult chickens were exposed for 48 h to a 525 Hz, 120 dB SPL tone that destroyed the hair cells and tectorial membrane in a crescent-shaped patch along the abneural edge of the basilar papilla. Single-unit recordings were obtained from cochlear ganglion neurons 0-1, 5, 14 and 28 days post-exposure to determine what effect the cochlear lesion had on neural discharge patterns and if the discharge patterns fully recovered. Immediately after exposure, the tuning curves were extremely broad and CF thresholds were elevated by 30-40 dB. In addition, the average spontaneous rate and percentage of neurons with interspike interval histograms with preferred intervals were greatly reduced. Tuning curves and spontaneous activity started to recover by 5 days post-exposure; however, some W-shaped tuning curves with two distinct tips and a hypersensitive tail were observed at this time. W-shaped tuning curves disappeared and spontaneous activity recovered to normal levels 14-28 days post-exposure. However, the CF thresholds of the most sensitive neurons were still slightly elevated, tuning curve slopes below CF were shallower than normal, and thresholds in the low-frequency tail of the tuning curves were often hypersensitive. These functional deficits were most closely associated with residual damage to the upper fibrous layer of the tectorial membrane. To determine if the cochlear frequency-place map was altered by the cochlear lesion, four physiologically characterized neurons were labeled with biocytin at 5 days post-exposure. The CFs of the labeled neurons were consistent with the normal frequency-place map (Chen et al. (1994) Hearing Research 81, 130-136) indicating that the tonotopic map was not altered.
成年鸡暴露于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非附着边缘呈新月形区域的毛细胞和盖膜。在暴露后0 - 1天、5天、14天和28天从耳蜗神经节神经元进行单单位记录，以确定耳蜗损伤对神经放电模式有何影响以及放电模式是否完全恢复。暴露后立即观察到，调谐曲线极宽，特征频率（CF）阈值升高30 - 40分贝。此外，平均自发放电率以及具有偏好间隔的峰峰间隔直方图的神经元百分比大幅降低。暴露后5天调谐曲线和自发放电活动开始恢复；然而，此时观察到一些具有两个明显峰值和一个超敏尾部的W形调谐曲线。W形调谐曲线在暴露后14 - 28天消失，自发放电活动恢复到正常水平。然而，最敏感神经元的CF阈值仍略有升高，CF以下的调谐曲线斜率比正常情况更平缓，并且调谐曲线低频尾部的阈值常常超敏。这些功能缺陷与盖膜上部纤维层的残留损伤密切相关。为了确定耳蜗损伤是否改变了耳蜗频率位置图，在暴露后5天对四个生理特征已明确的神经元用生物胞素进行标记。标记神经元的CF与正常频率位置图一致（Chen等人，《听觉研究》81卷，130 - 136页（1994年）），表明音频拓扑图未改变。
