Functional Organization of Somatosensory Cortex

描述(申请人提供)：这个项目的总体目标是了解大脑皮层中神经元对感觉刺激的反应是如何协调的，既有局部的，也有跨连接的皮质区域的。体感信息对指导许多运动行为很重要，这是通过从体感皮质到控制运动输出的大脑区域的投射来调节的。因此，对这些通路和支配初级躯体感觉(SI)皮质和初级运动(ML)皮质之间长距离相互作用的机制的了解的增加，应该有助于开发新的战略和技术，以康复遭受感觉损害的脑损伤个人： 我们将使用啮齿类动物SI桶状皮质作为动物模型来检验有关从SI到MI的皮质投射的几个假说。对于特定的目标1，在两个示踪剂离散沉积到MI的邻近焦点位置后，将描述SI桶状野中逆行标记神经元的分布。通过使用双重追踪范式，我们将确定汇聚在MI皮层焦点位置的SI神经元的地形图。对于特定的目标2，我们将同时记录SI桶皮质的多个神经元，以表征不同类型的神经元在感觉刺激过程中是如何相互协调的。因此，我们将描述以下三类神经元之间的放电协调或相对时序：a)投射到MI的SI神经元对，b)不投射到M1的SI神经元对，以及c)不同种类的投射和非投射神经元对。针对具体目标3，我们将同时记录SI和MI连接部分的多个神经元，以检验SI中相邻的投射神经元对相互协作激活MI皮质中共同的神经元靶点的假设。为了解决这个问题，条件互相关分析将被用来量化SI中同步活动对MI胡须表示的相应部分中神经元反应的概率的影响。

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.