Spectral integration by type II interneurons in dorsal cochlear nucleus.
Spectral integration by type II interneurons in dorsal cochlear nucleus.
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耳蜗背核中 II 型中间神经元的光谱整合。
DOI：
10.1152/jn.1999.82.2.648
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Young,ED
中科院分区：
文献类型：
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作者：
Spirou,GA;Davis,KA;Nelken,I;Young,ED
II型单位是耳蜗背核(DCN)中的一个显著的抑制性中间神经元，很可能是从垂直细胞记录到的。第二类单位的特点是自发活动率低，对宽带噪声的反应弱，对音调的反应强烈，窄调。第二类单位对宽带刺激的弱反应在下层听觉系统的神经元中是不寻常的，这表明这些单位接受强烈的抑制性输入，很可能来自耳蜗腹侧核的起始性C神经元。这里考虑了II型单位的定义问题；前面列出的特征定义了一个同质的II型组，但这个组与DCN中其他低自发频率神经元(I/III型单位)之间的边界尚不清楚。用双音调范式研究去大脑猫的II型单位，将抑制反应映射到音调，并使用不同宽度的噪声带研究宽带刺激诱发的抑制过程。荷包牡丹碱和士的宁的离子导入以及II型单位和听神经纤维之间的双音反应的比较被用来区分发生在细胞附近的抑制过程和耳蜗内的双音抑制。对于II型单位，在双音刺激下总是可以看到一个显著的抑制区域；这个区域的带宽大致对应于先前报道的Start-C神经元的兴奋带宽。用噪声带进行的带宽加宽实验显示，随着带宽的增加，反应呈单调下降；这些数据被解释为揭示了强烈的抑制输入，其特性更像Stack-C神经元，而不是较低听觉系统中的任何其他反应类型。与这些特性一致的是，抑制拮抗剂的离子导入使对宽带噪声的放电率大幅增加，使音调和噪声响应几乎相等。
The type II unit is a prominent inhibitory interneuron in the dorsal cochlear nucleus (DCN), most likely recorded from vertical cells. Type II units are characterized by low rates of spontaneous activity, weak responses to broadband noise, and vigorous, narrowly tuned responses to tones. The weak responses of type II units to broadband stimuli are unusual for neurons in the lower auditory system and suggest that these units receive strong inhibitory inputs, most likely from onset-C neurons of the ventral cochlear nucleus. The question of the definition of type II units is considered here; the characteristics listed in the preceding text define a homogeneous type II group, but the boundary between this group and other low spontaneous rate neurons in DCN (type I/III units) is not yet clear. Type II units in decerebrate cats were studied using a two-tone paradigm to map inhibitory responses to tones and using noisebands of varying width to study the inhibitory processes evoked by broadband stimuli. Iontophoresis of bicuculline and strychnine and comparisons of two-tone responses between type II units and auditory nerve fibers were used to differentiate inhibitory processes occurring near the cell from two-tone suppression in the cochlea. For type II units, a significant inhibitory region is always seen with two-tone stimuli; the bandwidth of this region corresponds roughly to the previously reported excitatory bandwidth of onset-C neurons. Bandwidth widening experiments with noisebands show a monotonic decline in response as the bandwidth increases; these data are interpreted as revealing strong inhibitory inputs with properties more like onset-C neurons than any other response type in the lower auditory system. Consistent with these properties, iontophoresis of inhibitory antagonists produces a large increase in discharge rate to broadband noise, making tone and noise responses nearly equal.