PLASTICITY OF BARREL FIELD INTRACORTICAL CIRCUITRY

描述(申请人提供)：拟议研究的目标是了解与胡须的触觉体验如何改变皮质桶周围隔区神经元的感受野(RF)，以及隔神经元在感觉处理和皮质可塑性中扮演什么角色。在解剖学上，第四层桶状神经元水平地投射到围绕着桶的隔膜中，垂直地在桶上方投射到第II-III层，在每个桶周围呈帽状图案。与由特定丘脑VPM输入主导的桶不同，隔神经元是来自丘脑的密度较低的输入和来自对侧皮质的连合输入的目标。当两个胡须几乎同时被刺激时，隔膜中的一些细胞表现出增强的(促进的)反应。如果两个胡须刺激之间有20-50毫秒的延迟，桶状细胞对第二个胡须的反应受到抑制，但隔细胞中不会研究与其位置有关的反应。我们认为隔区是对由几个触觉产生的输入的皮质反应进行修改的专门区域。我们的主要假设是，隔区的地形提供了一个分布的细胞矩阵，其中晶须输入的强度通过使用依赖的皮质内连接塑性来比较和修改。我们认为隔膜细胞作为感觉信息调节器发挥作用，因为它们整合了几个桶的活动，并相互反馈以修改桶状RF。我们将使用我们开发的可塑性测试--“晶须配对可塑性”--检验隔膜细胞对经验驱动的桶状细胞反应的修改有很大贡献的观点。具体地说，我们希望定义胡须经验在确定成人隔细胞可塑性中的作用，以表明依赖于使用的可塑性是如何受到发育调节的。对隔细胞的这些特征的分析将为桶状野皮质的感觉处理提供重要的新信息。这些结果将更好地理解感觉活动如何在一生中修改皮质神经元的RF，实验将指定由于早期感觉经验不足(感觉剥夺)而在隔神经元产生的整合缺陷。

DESCRIPTION (provided by applicant): The goal of the proposed research is to understand how tactile experience with the whiskers modifies the receptive field (RF) of neurons in the septa around cortical barrels, and what role septal neurons play in sensory processing and cortical plasticity. Anatomically, layer IV barrel neurons project horizontally into the septa surrounding the barrels and vertically above the barrel to layers II+III in a cap-like pattern that overlaps around each barrel. In contrast to barrels, which are dominated by specific thalamic VPM inputs, septal neurons are the cortical target of less dense inputs from the thalamus and commissural inputs from the contralateral cortex. When two whiskers are stimulated nearly simultaneously, some cells in the septum show increased (facilitated) responses. If there is a delay of 20-50 ms between whisker stimuli, the response to the second whisker is inhibited in barrel cells, but not studied in septal cells in relation to their location. We propose that the septa are specialized regions for modifying cortical responses to inputs that are generated by several vibrissa. Our main hypothesis is that the topography in the septal regions provides a distributed cell matrix in which the strength of whisker inputs is compared and modified through use-dependent, intracortical connection plasticity. We propose that septal cells operate as sensory information modulators in that they integrate the activity of several barrels and feed back reciprocally to modify barrel RF's. We will test the notion that septal cells contribute strongly to experience-driven modifications of barrel cell responses using a test for plasticity that we developed, called "whisker pairing plasticity". Specifically, we wish to define the role of whisker experience in determining adult septal cell plasticity to show how use-dependent plasticity is developmentally regulated. Analysis of these characteristics of the septal cells will provide significant new information about sensory processing in the barrel field cortex. The results will generate a better understanding of how sensory activity modifies the RF of cortical neurons throughout life, and the experiments will specify integrative deficits that are produced in septal neurons by inadequate early sensory experience (sensory deprivation).