Synaptic Receptive Field of Auditory Cortical Inhibitory Neuron

描述(由申请人提供)：实现对听觉皮质功能的理解的一个基本步骤是确定包含在感觉输入中的信息如何在不同的单个皮质神经元中被表示和处理。最近，几个实验室成功地将在体全细胞电压钳记录技术应用于大脑皮层神经元。这项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，从而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。虽然这项技术可以与后组织学方法相结合来重建记录细胞的形态，但它的盲性在很大程度上限制了它在检查皮质各种细胞类型方面的潜力，特别是那些体积小或空间稀疏的细胞；膜片钳记录技术通常会导致对皮质锥体神经元的偏向采样。 在这个探索性的项目中，我们将研究一种新的技术来揭示功能性突触输入到不同类型的单个皮质神经元上-双光子成像引导全细胞记录(TPGWC)，其中荧光标记的神经元通过双光子成像可视化并专门用于斑片记录。这项技术在很大程度上得益于小鼠遗传学的最新进展，即用荧光蛋白标记特定类型的细胞，如绿色荧光蛋白(GFP)，其表达受细胞类型特定启动子的控制。最初，我们计划将这种记录技术应用于GFP标记的小鼠初级听觉皮质(A1)输入层(L3/4)的GABA能中间神经元，并旨在解决两个基本问题：a)Al抑制神经元具有什么亚阈值/棘波TRF特性？B)皮层兴奋性和抑制性突触输入如何决定A1抑制神经元的阈值下/棘波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?