High Resolution of Mapping of Pain Ciruity in the Dorsal Horn

描述（由申请人提供）：近年来，疼痛研究在从基因到行为的各个层面都取得了革命性的进展。然而，有一个基本的组织水平已被证明特别难以分析，那就是在第一个中央中继区域（脊髓背角）内疼痛传递和调节的内在电路。有很多证据表明，内源性背角中间神经元的变化有助于炎症性和神经性疼痛的可塑性，但由于缺乏研究这种内源性电路的方法，进一步的理解受到限制。近年来，一项新技术的发展使得首次解剖紧密间隔的神经元件的突触连接的组织成为可能。通过激光扫描光刺激（LSPS）技术，记录单个神经元的突触反应，同时将激光诱导的谷氨酸释放产生的局部刺激传递到记录神经元周围组织的多个位置。所得到的图揭示了局部兴奋性和抑制性突触前神经元的位置，这些神经元向记录的神经元提供单突触输入。LSPS已经改变了我们对中枢神经系统许多领域回路的认识，但尚未用于疼痛系统。我们现在建议使用这种技术来研究背角中疼痛（伤害性）回路的组织。所提出的实验将绘制背角神经元的位置，这些神经元对层1投射神经元和层2中间神经元（胰岛细胞、中央细胞、垂直细胞和放射状细胞）产生局部兴奋性和抑制性突触输入。该方法基于一个假设，即背角内的内在连接模式是空间组织的，并且这种空间组织是背角功能的基本决定因素。我们进一步假设这种空间组织因兴奋性和抑制性输入而不同，并且是细胞类型特异性的。将该技术应用于背角，将促进我们对最近对背角的研究提出的模块化组织新概念的理解，并为背角电路的组织和可塑性开辟一个完整的研究领域。

DESCRIPTION (provided by applicant): In recent years, pain research has made revolutionary advances at levels ranging from genes to behavior. However, one basic level of organization that has proved particularly resistant to analysis is the intrinsic circuitry underlying pain transmission and modulation within the first central relay area, the spinal dorsal horn. There is much evidence that changes in intrinsic dorsal horn interneurons contribute to plasticity underlying inflammatory and neuropathic pain, but further understanding has been limited by a dearth of methods for studying this intrinsic circuitry. In recent years a novel technique was developed that has made it possible for the first time to dissect the organization of the synaptic connectivity of closely spaced neural elements. With this technique, laser scanning photostimulation (LSPS), synaptic responses are recorded in a single neuron while focal stimulation produced by laser-induced glutamate uncaging is delivered to multiple sites in the tissue surrounding the recorded neuron. The resulting map reveals the location of local excitatory and inhibitory pre-synaptic neurons that give monosynaptic input to the recorded neuron. LSPS has transformed our knowledge of circuitry in a many areas of the central nervous system, but has not yet been used in the pain system. We now propose to use this technique to study the organization of pain (nociceptive) circuitry in the dorsal horn. The proposed experiments will map the locations of dorsal horn neurons that give rise to local excitatory and inhibitory synaptic input to lamina I projection neurons and lamina II interneurons (islet, central, vertical, and radial cells). This approach is based on the hypothesis that the pattern of intrinsic connectivity in the dorsal horn is spatially organized, and that this spatial organization is a fundamental determinant of dorsal horn function. We further hypothesize that this spatial organization differs for excitatory and inhibitory inputs, and is cell-type specific. The application of this technique to the dorsal horn will advance our understanding of the new concept of a modular organization that has been proposed from recent studies of the dorsal horn, and open up an entire field of investigation into the organization and plasticity of dorsal horn circuitry.