Cochlear nerve activity after intense sound exposure in neonatal chicks.
Cochlear nerve activity after intense sound exposure in neonatal chicks.
复制标题
新生雏鸡暴露于强烈声音后的耳蜗神经活动。
DOI：
10.1152/jn.1996.76.2.770
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Fisher,KA
中科院分区：
文献类型：
--
作者：
Saunders,JC;Doan,DE;Poje,CP;Fisher,KA
1.用120 dB SPL纯音（0.9 kHz）刺激新生（3日龄）雏鸡48 h，观察其耳蜗神经单神经元行为。在恢复0天或12天后对暴露动物进行检测。未接触的小鸡，年龄匹配的接触动物，形成两个对照组。2.从每个细胞获得光谱响应图。这些图描述了神经元对1,767种短纯音刺激的放电率，每种刺激都有独特的频率-强度组合。在0.1和4.5 kHz之间的频率和0和100 dB SPL之间的强度的纯音。从这些曲线图中，得出每个单元的特征频率（CF）、CF阈值和调谐锐度（Q10 dB）。频率响应面积函数在选定的刺激水平和率强度函数在CF也构建了光谱响应图。此外，还测定了自发活动。数据来自903个细胞。3.在控制细胞中的神经元活动显示CF阈值，Q10 dB，或自发活动在两个年龄组之间没有差异。然而，在所有频率的年龄差异率强度函数。4.在0天恢复的细胞中观察到CF阈值的频率依赖性损失。阈值偏移（相对于年龄匹配的对照细胞）在0.8和1.5 kHz之间为55-65 dB，但在0.1-0.4 kHz和2.5-3.5 kHz之间仅为10-15 dB。暴露的细胞在< 0.5 kHz时没有表现出频率选择性（Q10 dB）的损失，而在该频率以上，注意到调谐的恶化增加。在整个CF范围内，0天细胞的自发活动受到抑制。暴露细胞的速率-强度函数比对照细胞具有更陡的生长速率。5.在12天的恢复，CF阈值，Q10 dB，和自发活动都恢复到年龄匹配的对照细胞所表现出的水平。然而，频率-强度函数的细胞与CFs在0.8和1.0 kHz之间表现出异常的增长和更高的放电率在饱和比对照细胞。在此频率范围之外，对照和暴露细胞的速率-强度函数彼此相似。6.声音损伤的鸡耳的功能恢复伴随着基底乳头的几乎完全修复。然而，盖膜保留了一个主要的缺陷，只有下层的膜再生。在本演示文稿中的一个重要观察是异常率强度功能（在12天恢复的细胞）报告的频率服务的感觉上皮的区域，其中发现覆膜defictions. This观察可能与持续的结构损伤的短毛细胞区域的乳头和/或在由短毛细胞介导的乳头功能的传出控制的改变。
1. Single-neuron behavior in the cochlear nerve of neonatal (3-day-old) chicks was examined after exposure to a 120-dB SPL pure tone (0.9 kHz) for 48 h. Exposed animals were tested after 0 days or 12 days of recovery. Nonexposed chicks, age-matched to the exposed animals, formed two control groups. 2. Spectral response plots were obtained from each cell. These plots described the neuron discharge rates in response to 1,767 tone burst stimuli, each with a unique frequency-intensity combination. The tone bursts were presented at frequencies between 0.1 and 4.5 kHz and for intensities between 0 and 100 dB SPL. From these plots the characteristic frequency (CF), CF threshold, and sharpness of tuning (Q10 dB) were derived for each cell. Frequency response-area functions at selected stimulus levels and rate-intensity functions at the CF were also constructed from the spectral response plots. In addition, spontaneous activity was determined. Data were obtained from 903 cells. 3. Neuron activity in the control cells revealed no differences between CF thresholds, Q10 dB, or spontaneous activity in the two age groups. However, age differences at all frequencies were noted in the rate-intensity functions. 4. A frequency-dependent loss in CF threshold was observed in the 0-day recovered cells. The threshold shift (relative to age-matched control cells) was 55-65 dB between 0.8 and 1.5 kHz, but only 10-15 dB between 0.1-0.4 kHz and 2.5-3.5 kHz. The exposed cells showed no loss in frequency selectivity (Q10 dB) at < 0.5 kHz, whereas above this frequency an increasing deterioration in tuning was noted. Spontaneous activity in the 0-day cells was suppressed across the entire range of CFs. The rate-intensity function of exposed cells had a steeper growth rate than that of control cells. 5. At 12 days of recovery, CF threshold, Q10 dB, and spontaneous activity all recovered to the levels exhibited by age-matched control cells. However, the rate-intensity function for cells with CFs between 0.8 and 1.0 kHz showed abnormal growth and higher discharge rates at saturation than the control cells. Outside of this frequency range the rate-intensity functions of control and exposed cells were similar to each other. 6. Recovery of function in the sound-damaged chick ear is accompanied by almost complete repair of the basilar papilla. The tectorial membrane, however, retains a major defect and only the lower layer of this membrane regenerates. An important observation in this presentation was the abnormal rate-intensity functions (in the 12-day recovered cells) reported for frequencies served by that region of the sensory epithelium where the tectorial membrane defect was found. This observation may be related to sustained structural damage to the short hair cell region of the papilla and/or alterations in the efferent control of papilla function mediated by the short hair cells.