Effect of unilateral noise exposure on the tonotopic distribution of spontaneous activity in the cochlear nucleus and inferior colliculus in the cortically intact and decorticate rat
Effect of unilateral noise exposure on the tonotopic distribution of spontaneous activity in the cochlear nucleus and inferior colliculus in the cortically intact and decorticate rat
复制标题
DOI：
10.1002/cne.20674
复制
发表时间：
2005-10-03
影响因子：
2.5
通讯作者：
Durham, D
中科院分区：
文献类型：
--
作者：
Imig, TJ;Durham, D
本实验观察了单侧噪声暴露对正常大鼠和去皮质大鼠耳蜗前腹侧核(AVCN)、耳蜗背侧核(DCN)和下丘中央核(ICC)自发活动的影响。暴露1周后，安静状态下摄取C-14标记的2-脱氧葡萄糖(2DG)，测量SA。在每个核的低频和高频(LF和HF)区域进行光密度(OD)测量。我们将同侧的AVCN和DCN(噪声暴露耳的一侧)和对侧的ICC称为直接核，将其对侧的对应核称为间接核。噪声暴露引起HIP OD/LFOD比值(HF/LF比值)降低，从而改变了SA在直接通路上的强直曲线。在完整动物中，HF/LF比值的降低是由于髋关节OD的降低。在去皮层动物中，这是由于HF OD减少和LF OD增加所致，后者主要发生在DCN和ICC。去皮质完整的差异可能反映了皮质分离反馈抑制。损毁背听纹可引起对侧ICC内SA的显著降低。此外，DCN、AVCN和对侧ICC的HF/LF比值呈显著正相关，提示耳蜗核是ICC内SA的主要来源。噪声暴露对间接途径的2DG摄取有相反的、较弱的影响，并归因于交叉抑制。噪声引起的SA强直曲线的改变可能代表了耳鸣的神经关联。
Effects of unilateral noise exposure on spontaneous activity (SA) in the anteroventral and dorsal cochlear nuclei (AVCN and DCN) and the central nucleus of the inferior colliculus (ICc) were studied in cortically intact and decorticate rats. SA was measured I week following exposure using uptake of C-14-labeled 2-deoxyglucose (2DG) in quiet. Optical density (OD) measurements were obtained in low- and high-frequency (LF and HF) areas of each nucleus. We refer to the ipsilateral AVCN and DCN (side of the noise-exposed ear) and the contralateral ICc as direct nuclei and to their opposite side counterparts as indirect nuclei. Noise exposure altered the tonotopic profile of SA in the direct pathway by causing a decrease in the ratio of HIP OD to LF OD (HF/LF ratio). In intact animals, the decreased HF/LF ratio was due to decreased HIP OD. In decorticate animals, it was due to decreased HF OD and increased LF OD, the latter occurring mainly in the DCN and ICc. Decorticate-intact differences may reflect corticofugal feedback inhibition. Lesion of the dorsal acoustic stria caused a substantial decrement of SA in the contralateral ICc. Furthermore, strong positive correlations between HF/LF ratios in the DCN, AVCN, and contralateral ICc suggest that the cochlear nucleus is a major contributor to SA in the ICc. Noise exposure had opposite and weaker effects on 2DG uptake in the indirect pathway that were attributed to crossed inhibition. Noise-induced changes in the tonotopic profile of SA may represent a neural correlate of tinnitus.