Identification of inputs to unipolar brush cells and their roles in multisensory processing

项目总结/摘要 单极刷状细胞（unipolar brush cell，UBC）是位于耳蜗背核的一种兴奋性中间神经元细胞 (DCN)和前庭小脑UBC位于电路内以放大和延长信号， 可能在多感觉整合，声源定位和消除自我产生的声音中发挥重要作用。 声音. UBC有一个典型的大树枝状刷子，减缓了谷氨酸盐从突触的扩散。 突触和突触兴奋信号。多感觉输入通过苔藓纤维传递到UBC。Trussell实验室 发现有两种类型的UBC-一种对苔藓纤维释放的谷氨酸产生反应， 一种是增加发射（ON UBC），另一种是减少发射（OFF UBC）。我最近 发现在前庭小脑中，ON UBC从前庭小脑直接接受初级传入输入， 神经节细胞，而OFF UBC接受来自前庭核的间接次级输入。UBC也是预- 在耳蜗背核（DCN）发送，但他们的苔藓纤维输入是未知的。目标1将采用创新的 识别DCN中UBC亚型输入源的工具和方法。目标2将测试UBC的突触 对这些投入的回应。目标3，R 00阶段，将在体内测试UBC的功能和电路。 这项建议利用了在使用方面具有专门知识的导师和顾问的指导下采用的先进方法。在 目的1，基于我在前庭系统中的发现，我将检验在DCN初级感觉中 苔藓纤维投射到ON UBC，次级苔藓纤维投射到OFF UBC。此目标利用鼠标 基因特异性靶向ON或OFF UBC，以及假型狂犬病病毒的单突触传递， 识别突触前苔藓纤维来源。在目标2中，将通过表达 通道视紫红质在投射源和记录突触后电流在UBC使用在体外电 physiology.目标3在R 00阶段将结合联合收割机的技能，我学到了作为一个博士后与我的背部- 使用体内电生理学接地。将通过记录测试DCN电路中UBC的功能 在ON或OFF UBC的光遗传学激活期间来自主要输出（梭形）神经元。的作用 将通过光遗传学抑制ON或OFF UBC来测试UBC门控DCN的多感觉输入。 这项研究将阐明这些迷人的兴奋性中间神经元在多感觉整合中的作用。是- 由于UBC在兴奋性信号放大中的潜在作用，这项工作可能会提供对UBC在兴奋性信号放大中的作用的见解。 耳鸣的病因

PROJECT SUMMARY / ABSTRACT The unipolar brush cell (UBC) is an excitatory interneuron cell type found in the dorsal cochlear nucleus (DCN) and vestibular cerebellum. UBCs are positioned within the circuit to amplify and prolong signals and likely play a major role in multisensory integration, sound source localization and cancellation of self-generated sounds. The UBC has a characteristic large dendritic brush that slows the diffusion of glutamate from the syn- apse and prolongs excitatory signals. Multisensory input is carried to UBCs by mossy fibers. The Trussell Lab has found that there are two types of UBCs- one responds to glutamate released from mossy fibers with an increase in firing (ON UBCs) and another that responds with a decrease in firing (OFF UBCs). I have recently discovered that in the vestibular cerebellum, ON UBCs receive direct primary afferent input from vestibular ganglion cells, whereas OFF UBCs receive indirect secondary input from vestibular nuclei. UBCs are also pre- sent in the dorsal cochlear nucleus (DCN), but their mossy fiber inputs are unknown. Aim 1 will use innovative tools and approaches to identify sources of input to UBC subtypes in DCN. Aim 2 will test the UBCs’ synaptic responses to those inputs. Aim 3, the R00 phase, will test the function and circuitry of UBCs in vivo. This proposal utilizes cutting-edge approaches under mentors and consultants with expertise in their use. In Aim 1, motivated by my findings in the vestibular system, I will test the hypothesis that in DCN primary sensory mossy fibers project to ON UBCs and secondary mossy fibers project to OFF UBCs. This Aim utilizes mouse genetics to target ON or OFF UBCs specifically, and monosynaptic transmission of pseudotyped rabies virus to identify presynaptic mossy fiber sources. In Aim 2 the pathways identified will be validated by expressing channelrhodopsin in the projecting sources and recording postsynaptic currents in UBCs using in vitro electro- physiology. Aim 3 during the R00 phase will combine the skills I have learned as a postdoc with my back- ground using in vivo electrophysiology. The function of UBCs in the DCN circuit will be tested by recording from the principal output (fusiform) neurons during optogenetic activation of ON or OFF UBCs. The role of UBCs in gating multisensory inputs to DCN will be tested by inhibiting ON or OFF UBCs optogenetically. This research will clarify the role of these fascinating excitatory interneurons in multisensory integration. Be- cause of UBCs’ potential role in the amplification of excitatory signals, this work may provide insights into an etiology of tinnitus.