Evidence of a functionally segregated pathway from dorsal cochlear nucleus to inferior colliculus
Evidence of a functionally segregated pathway from dorsal cochlear nucleus to inferior colliculus
复制标题
DOI：
10.1152/jn.00769.2001
复制
发表时间：
2002-04-01
影响因子：
2.5
通讯作者：
Davis, KA
中科院分区：
文献类型：
--
作者：
Davis, KA
去脑猫下丘中央核（ICC）的O型单位在阈附近被最佳频率（BF）音兴奋，但在所有频率上被高强度音抑制。耳蜗背核（DCN）主细胞显示出类似的反应图特征，并直接投射到ICC，因此被认为是O型单位兴奋性输入的主要来源。为了验证这一假设，O型单位的反应进行了比较之前和之后的两个药理学操作。当DCN到ICC的轴突被利多卡因压力注射阻断时，大多数O型单位（约80%）被沉默或表现出明显的活性降低，但有些单位表现出活性增加。所有的前单位有低的最大速率BF音，而后者的单位有高利率。当局部电路的抑制机制在ICC被阻断的离子电渗应用荷包牡丹碱或士的宁，O型单位的反应也分为两类：低速率的单位，表现出增加自发和驱动的活动和高速率的单位，显示，此外，改变响应地图功能。两者合计，这些结果表明，低速率O型单位是由DCN启动的功能分离途径的一部分，而高速率O型单位是在ICC水平上产生的。
Type O units in the central nucleus of the inferior colliculus (ICC) of decerebrate cats are excited by best frequency (BF) tones near threshold, but are inhibited by high-level tones at all frequencies. Dorsal cochlear nucleus (DCN) principal cells display similar response map features and project directly to the ICC, and are thus supposed to be the dominant source of excitatory input for type O units. To test this hypothesis, the responses of type O units were compared before and after two pharmacological manipulations. When DCN to ICC axons were blocked by pressure injections of lidocaine, most type O units (similar to80%) were silenced or showed substantially reduced activity, but some units showed increased activity. All of the former units had low maximal rates to BF tones, whereas the latter units had high rates. When local circuit inhibitory mechanisms in the ICC were blocked by iontophoretic application of bicuculline or strychnine, type O unit responses also fell into two classes: low-rate units that showed increased spontaneous and driven activities and high-rate units that showed, in addition, altered response map features. Taken together, these results demonstrate that low-rate type O units are part of a functionally segregated pathway initiated by the DCN, whereas high-rate type O units are created at the level of the ICC.