Electrical stimulation of the auditory nerve - III. Response initiation sites and temporal fine structure
Electrical stimulation of the auditory nerve - III. Response initiation sites and temporal fine structure
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DOI：
10.1016/s0378-5955(99)00186-0
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发表时间：
2000-02-01
期刊：
影响因子：
2.8
通讯作者：
Shepherd, RK
中科院分区：
文献类型：
--
作者：
Javel, E;Shepherd, RK
对正常和慢性耳聋猫耳中听觉神经纤维对电脉冲序列的反应的潜伏期、时间分散和输入输出特征进行了分类，并暂时与启动活动的部位相关联。尖峰发生在四个离散时间范围中的一个或多个，其端点部分重叠。 A 响应的延迟 < 0.44 ms，表现出 8-12 mu s 的渐近时间色散，并且对于 200 个脉冲/秒 (pps) 脉冲串具有 1.2 dB 的平均动态范围。它们可能起源于螺旋神经节细胞的中央突起。 B-1 和 B-2 反应（0.45-0.9 ms、25-40 mu s、1.9 dB）可能分别源于有髓鞘和无髓鞘外周过程的活动。 C 响应（0.9-1.2 ms，> 100 mu s）可能源自内毛细胞的直接刺激，D 响应（> 1.1 ms，> 100 mu s，> 8 dB）源自可能由外毛细胞的电诱导运动引起的传播行波。 C 和 D 反应仅在声学反应耳中记录。所有时间范围内尖峰的平均潜伏期通常随着强度的增加而降低，并且在同一尖峰序列中经常观察到两个甚至三个离散潜伏期的活动。随着强度的增加，潜伏期从一个离散时间范围转移到另一个离散时间范围通常会发生。一些变化可能归因于对双相脉冲的相反极性相位的响应。在这些情况下，每个潜伏期的活动的时间色散和动态范围大致相等。还经常观察到第二种类型的潜伏期变化，其中每个潜伏期的响应表现出不同的时间分散和动态范围。这种行为归因于尖峰起始位点的向中心移动，并且它发生在单相和双相信号中。一些纤维表现出双潜伏期活性，响应峰之间的时间差为 40-90 μs。这可能源于细胞体两侧节点处的尖峰起始。将刺激脉冲速率增加到 800-1000 pps 会导致时间色散小幅增加，并且渐进放电速率和动态范围成比例增加，但阈值没有改善，速率强度函数的斜率（以尖峰/s/dB 为单位）没有改变。当放电速率超过 300-400 尖峰/秒时，对高速率刺激的响应也表现出离散延迟增加，在这些情况下，尖峰延迟在很大程度上取决于放电历史；讨论了对高速语音处理策略的影响。 (C) 2000 Elsevier Science B.V. 保留所有权利。
Latency, temporal dispersion and input-output characteristics of auditory nerve fiber responses to electrical pulse trains in normal and chronically deafened cat ears were classified and tentatively associated with sites where activity is initiated. Spikes occurred in one or more of four discrete time ranges whose endpoints overlapped partially. A responses had latencies < 0.44 ms, exhibited asymptotic temporal dispersion of 8-12 mu s and possessed an average dynamic range of 1.2 dB for 200 pulses/s (pps) pulse trains. They likely originated from central processes of spiral ganglion cells. B-1 and B-2 responses (0.45-0.9 ms, 25-40 mu s, 1.9 dB) likely stemmed from activity at myelinated and unmyelinated peripheral processes, respectively. C responses (0.9-1.2 ms, > 100 mu s) likely originated from direct stimulation of inner hair cells, and D responses (> 1.1 ms, > 100 mu s, >8 dB) arose from propagating traveling waves possibly caused by electrically induced motion of-outer hair cells. C and D responses were recorded only in acoustically responsive ears. Mean latencies of spikes in all time ranges usually decreased with intensity, and activity at two or even three discrete latencies was often observed in the same spike train. Latency shifts from one discrete time range to another often occurred as intensity increased, Some shifts could be attributed to responses to the opposite-polarity phase of the biphasic pulse, In these cases, temporal dispersion and dynamic range were approximately equal for activity at each latency. A second type of latency shift was also often observed, in which responses at each latency exhibited dissimilar temporal dispersion and dynamic range. This behavior was attributed to a centralward shift in the spike initiation site and it occurred for monophasic as well as biphasic signals. Several fibers exhibited dual latency activity with a 40-90 mu s time difference between response peaks. This may have stemmed from spike initiation at nodes on either side of the cell body. Increasing the Stimulus pulse rate to 800-1000 pps produced small increases in temporal dispersion and proportionate increases in asymptotic discharge rate and dynamic range, but thresholds did not improve and slopes of rate-intensity functions (in spikes/s/dB) did not change. Responses to high-rate stimuli also exhibited discrete latency increases when discharge rates exceeded 300-400 spikes/s, Spike by spike latencies in these cases depended strongly on the discharge history; Implications for high-rate speech processing strategies are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.