树鼩下丘-内侧膝状体-听皮层上下行听觉传导通路形态学研究

As the last relaying nucleus of the auditory pathway, the medial geniculate body has a complex neural network structure with the ascending and descending nuclei. In our preliminary study, six typical ABR waves were induced by the short-stimulated tree shrews, and we also successfully established the medial geniculate body injured tree shrew model, The Ⅵ wave of ABR was decreased or even disappeared, and Ⅴ wave amplitude decreased in tree shrew, it implied the Ⅵ wave may be related to the medial geniculate body. The nuclei returned to the preoperative amplitude level 15-30 days after the injury, indicating that tree shrews have self-repair and plastic ability. So we think that the medial geniculate body plays an important role in auditory conduction plasticity. This project take it as an opportunity , the tree shrew with medial geniculate body sub-nuclear injury as the experimental object, to synthesize the neuronal tract tracing, the auditory system electrophysiology, the voxel-based morphometry (VBM) and DTI magnetic resonance processing technology, to address the following questions: ①To observe the relationship between the nuclei of the inferior collicular - medial geniculate body -auditory cortex and the fiber projection of the tree shrews; ②To analyze the changes of auditory brainstem response and middle latency auditory evoked potential in tree shrews; ③ To calculate the tree shrews brain structure and white matter fiber bundle changes. The aim of this study is to explore the mechanism of auditory plasiticity from the perspective of histomorphology, and to provide theoretical basis for the further study of auditory pathway function.

内侧膝状体作为听觉传导通路最后一级中继核团，与上下级核团有着复杂的神经网络结构。本课题组前期通过短声刺激树鼩诱发出6个典型的ABR波，成功建立了树鼩内侧膝状体损伤模型，发现树鼩ABR的Ⅵ波明显下降甚至消失，Ⅴ波振幅下降，提示Ⅴ、Ⅵ波的产生可能与内侧膝状体有关。各核团在损毁后15-30天时恢复到术前振幅水平，表明树鼩听觉通路具有自我修复及重塑能力。故我们认为内侧膝状体在听觉传导重塑中起着重要的作用。本项目以此为契机，以树鼩内侧膝状体各亚核团损伤模型为实验对象，综合应用神经束路示踪、听觉系统电生理、基于体素的型态学测量（VBM）和DTI磁共振处理技术，探讨以下问题：①观察树鼩下丘-内侧膝状体-听皮层各核团及其纤维投射关系；②分析树鼩听性脑干反应、中潜伏诱发电位变化特点；③计算树鼩脑结构和白质纤维束的改变情况。本研究旨在从组织形态学角度探讨听觉重塑机制，为进一步听觉通路功能研究提供理论依据。

内侧膝状体作为听觉传导通路最后一级中继核团，与上下级核团有着复杂的神经网络结构。本课题组前期通过短声刺激树鼩诱发出6个典型的ABR波，并进行记录分析。本项目研究旨在从组织形态学角度探讨听觉重塑机制，为进一步听觉通路功能研究提供理论依据。我们通过对正常树鼩及MGB损毁后树鼩进行试验，测量听性脑干反应，采集树鼩大脑磁共振T1WI、T2W2、 DTI 数据，进行确定性的纤维追踪及 DTI 定量分析， 将脑组织切片进行 HE 染色和尼氏染色。作为研究结果，我们发现树鼩具有与人类相似的下丘-内侧膝状体-听皮层的纤维投射解剖结构，记录收集了大量树鼩大脑的神经纤维形态学资料，实验采用树鼩作为耳神经科学研究的新型动物，扩充了耳科动物模型种类，为今后进一步听觉导通路的功能研究，特别是多感觉整合作用、频率编码、听觉可塑性、声学模型的建立等提供形态学基础。树鼩双侧内侧膝状体损毁后神经纤维发生 Wallerian 变性， 3 个月内解剖结构难以恢复，且功能重塑先于结构重塑，这为临床上神经性耳聋患者听力代偿研究提供实验基础。