Functional Organization of Somatosensory Cortex

描述（由申请人提供）：该项目的总体目标是了解神经元对感觉刺激的反应如何在大脑皮层中协调，包括局部和跨连接的皮层区域。躯体感觉信息对于指导许多运动行为是重要的，并且这通过从躯体感觉皮层到参与控制运动输出的脑区域的投射来介导。因此，增加对这些通路和控制初级躯体感觉（SI）皮层和初级运动（MI）皮层之间的长程相互作用的机制的了解，应该有助于开发新的策略和技术，用于康复遭受感觉障碍的脑损伤个体： 我们将使用啮齿动物SI桶皮质作为动物模型，以测试几个假设有关的皮质皮质预测从SI到MI。对于特定目标1，将在两种示踪剂离散沉积到MI的相邻病灶部位后，表征SI桶场中逆行标记神经元的分布。通过使用双重跟踪范例，我们将确定的拓扑结构的SI神经元，在MI皮层的焦点网站收敛。对于特定目标2，我们将同时记录SI桶皮质中的多个神经元，以表征不同类型的神经元在感觉刺激期间如何相互协调。因此，我们将表征以下神经元之间的放电的协调或相对定时：a）投射到MI的SI神经元对，B）不投射到MI的SI神经元对，以及c）投射和非投射神经元的异质对。对于特定目标3，我们将同时记录SI和MI的连接部分中的多个神经元，以测试SI中相邻的投射神经元对彼此合作以激活MI皮质中的共同神经元靶点的假设。为了解决这个问题，条件互相关分析将被用来量化SI的同步活动的影响，在MI晶须表示的相应部分的神经元反应的概率。

DESCRIPTION (provided by applicant): The overall goal of this project is to understand how neuronal responses to sensory stimuli are coordinated in the cerebral cortex, both locally and across connnected cortical areas. Somatosensory information is important for guiding many motor behaviors, and this is mediated by projections from somatosensory cortex to brain regions involved in controlling motor output. Hence, increased knowledge of these pathways and the mechanisms that govern long-range interactions between the primary somatosensory (SI) cortex and the primary motor (Ml) cortex should facilitate the development of new strategies and techniques for rehabilitating brain-damaged individuals that suffer sensory impairment: We will use the rodent SI barrel cortex as an animal model to test several hypotheses concerning the corticocortical projections from SI to MI. For Specific Aim 1, the distribution of retrogradely-labled neurons in the barrel field of SI will be characterized following discrete deposits of two tracers into neighboring focal sites of MI. By using a dual tracing paradigm, we will determine the topography of SI neurons that converge on focal sites in MI cortex. For Specific Aim 2, we will simultaneously record multiple neurons in SI barrel cortex to characterize how different types of neurons are coordinated with each other during sensory stimulation. Thus, we will characterize the coordination or relative timing of discharges among: a) pairs of SI neurons that project to MI, b) pairs of SI neurons that do not project to Ml, and c) heterogeneous pairs of projection and non-projection neurons. For Specific Aim 3 we will simultaneously record multiple neurons in connected parts of SI and MI to test the hypothesis that neighboring pairs of projection neurons in SI cooperate with each other to activate common neuronal targets in MI cortex. To address this issue, conditional cross-correlation analysis will be used to quantify the impact of synchronized activity in SI on the probability of neuronal responsiveness in corresponding parts of the MI whisker representation.