Auditory nerve inputs to cochlear nucleus neurons studied with cross-correlation.
Auditory nerve inputs to cochlear nucleus neurons studied with cross-correlation.
复制标题
通过互相关研究耳蜗核神经元的听觉神经输入。
DOI：
10.1016/j.neuroscience.2008.01.036
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发表时间：
2008
期刊：
影响因子：
3.3
通讯作者：
Sachs,MB
中科院分区：
文献类型：
--
作者：
Young,ED;Sachs,MB
听神经纤维与腹侧耳蜗核（VCN）神经元之间突触的强度是决定不同反应类型VCN神经元神经整合性质的重要因素。通过对麻醉猫的an纤维和VCN神经元同时记录的脉冲序列进行相互关联分析突触强度。根据先前定义的标准，VCN神经元分为斩波型、原发型和发作型，但由于发作型神经元放电率低，通常不进行分析。相关图显示最佳频率相似的an - vcn对存在兴奋峰（EP），与单突触兴奋一致（49% /49对最佳频率在±5%以内）。斩波神经元和初级样神经元的EPs相似，但初级样神经元的潜伏期更短，EPs持续时间更短。在球形丛状细胞上没有观察到与球末端一致的大EPs，可能是由于从一个细胞记录的概率较低。在原代样神经元中观察到的小EPs，可能来自这些细胞上伴随端球的小终末。斩叶状或原代样带缺口神经元上的EPs与多极和球状丛状细胞上较小的突触末端一致。出乎意料的是，EPs仅在阈值约20 dB的声级范围内被观察到，这表明VCN对稳定音调的反应从低声级时AN和VCN峰值之间的1:1关系转变为高声级时更自主的发射模式。在高电平模式下，输出尖峰的模式似乎是由突触后尖峰发生器的特性决定的，而不是由输入尖峰模式决定的。当突触前的峰间间隔较短或较长时，电位振幅变化不显著，提示在本研究条件下，突触抑制和促进作用不大。
The strength of synapses between auditory nerve (AN) fibers and ventral cochlear nucleus (VCN) neurons is an important factor in determining the nature of neural integration in VCN neurons of different response types. Synaptic strength was analyzed using cross-correlation of spike trains recorded simultaneously from an AN fiber and a VCN neuron in anesthetized cats. VCN neurons were classified as chopper, primarylike, and onset using previously defined criteria, although onset neurons usually were not analyzed because of their low discharge rates. The correlograms showed an excitatory peak (EP), consistent with monosynaptic excitation, in AN–VCN pairs with similar best frequencies (49% 24/49 of pairs with best frequencies within ±5%). Chopper and primarylike neurons showed similar EPs, except that the primarylike neurons had shorter latencies and shorter-duration EPs. Large EPs consistent with end bulb terminals on spherical bushy cells were not observed, probably because of the low probability of recording from one. The small EPs observed in primarylike neurons, presumably spherical bushy cells, could be derived from small terminals that accompany end bulbs on these cells. EPs on chopper or primarylike-with-notch neurons were consistent with the smaller synaptic terminals on multipolar and globular bushy cells. Unexpectedly, EPs were observed only at sound levels within about 20 dB of threshold, showing that VCN responses to steady tones shift from a 1:1 relationship between AN and VCN spikes at low sound levels to a more autonomous mode of firing at high levels. In the high level mode, the pattern of output spikes seems to be determined by the properties of the postsynaptic spike generator rather than the input spike patterns. The EP amplitudes did not change significantly when the presynaptic spike was preceded by either a short or long interspike interval, suggesting that synaptic depression and facilitation have little effect under the conditions studied here.