Synaptic Receptive Field of Auditory Cortical Inhibitory Neuron

描述（由申请人提供）：理解听觉皮层功能的一个重要步骤是确定感觉输入中包含的信息如何在不同的个体皮层神经元中表示和处理。最近，一些实验室已经成功地将“盲”在体全细胞电压钳记录技术应用于皮层神经元。该技术可以将感觉驱动的兴奋性和抑制性突触输入解析到记录的神经元上，使得可以构建突触连接模型来预测神经元在任意感觉刺激下的反应。虽然这种技术可以与事后组织学方法相结合，以重建记录的细胞的形态，其“盲目”的性质在很大程度上限制了其潜力，在检查各种类型的细胞在皮层，特别是那些小的尺寸或空间稀疏;“盲目”膜片钳记录技术通常会导致在一个有偏见的采样锥体神经元在皮层。 在这个探索性的项目中，我们将研究一种新的技术，用于揭示不同类型的单个皮层神经元双光子成像引导的全细胞（TPGWC）记录的功能突触输入，其中荧光标记的神经元通过双光子成像可视化，并专门针对补丁记录。该技术在很大程度上受益于小鼠遗传学中用荧光蛋白标记特定细胞类型的最新发展，所述荧光蛋白例如绿色荧光蛋白（GFP），其表达由细胞类型特异性启动子控制。首先，我们计划将这种记录技术应用于小鼠初级听觉皮层（A1）输入层（L3/4）中GFP标记的GABA能中间神经元，并旨在解决两个基本问题：a）Al抑制性神经元具有什么样的阈下/尖峰TRF特性？B）皮层兴奋性和抑制性突触输入如何决定A1抑制性神经元的阈下/峰电位TRF结构？

Description (provided by applicant): An essential step to achieving an understanding of auditory cortical function is determining how information contained in sensory inputs is represented and processed in different individual cortical neurons. Recently, several laboratories have successfully applied a "blind" in vivo whole-cell voltage-clamp recording technique to cortical neurons. This technique can resolve sensory-driven excitatory and inhibitory synaptic inputs onto the recorded neuron, making it possible to construct a synaptic connectivity model to predict the neuron's response under arbitrary sensory stimulation. Although this technique can be combined with post hoc histological methods to reconstruct the morphology of recorded cells, its "blind" nature largely limits its potential in examining various cell types in the cortex, especially those that are small in size or spatially sparse; the "blind" patch-clamp recording technique will normally result in a biased sampling of pyramidal neurons in the cortex. In this exploratory project, we will study a new technique for revealing functional synaptic inputs made onto different types of individual cortical neurons two-photon imaging guided whole-cell (TPGWC) recording in which fluorescence-labeled neurons are visualized by two-photon imaging and specifically targeted for patch recording. This technique has largely benefited from recent developments in mouse genetics in the labeling of specific cell types with fluorescence proteins, such as green fluorescence protein (GFP), whose expression is controlled by cell-type specific promoters. Initially, we plan to apply this recording technique to GFP-labeled GABAergic interneurons in the input layers (L3/4) of the mouse primary auditory cortex (A1), and aim at addressing two fundamental questions: a) What subthreshold/spike TRF properties are possessed by Al inhibitory neurons? b) How do cortical excitatory and inhibitory synaptic inputs determine subthreshold/spike TRF structure of A1 inhibitory neurons?