RECEPTIVE FIELDS OF LAYER IV (BARREL FIELD) NEURONS

躯体感觉皮层中的神经元接收来自大脑皮层的感觉信息。 在整个出生后的生活。关于这个问题的中心假设 建议的研究是，简单的积极偏见的水平正在进行的 来自所选晶须的活性足以增强它们的靶向 通过谷氨酸受体机制在皮层形成突触。研究 将在大鼠须到桶场皮层通路中进行 因为每个晶须中的离散的、不重叠的受体 保持一个清晰的地形，包括桶场的第四层 皮层此外，我们已经证明， 成年大鼠桶场皮层神经元通过简单的修剪进行修饰 一些，但不是全部，胡须的时间短至1天或长达 30天.修剪所有，但两个相邻的晶须显着增加 皮质神经元对多余胡须的反应， 减少了对剪胡须的反应。晶须引起的变化 配对是多方面的，取决于细胞在桶中的位置 场皮层，桶的关系，每个胡须在接受 以及它们被修剪或保留的时间。四个具体目标是 确定分析电路和机制，支持这些 成年大鼠皮质的可塑性反应：目的#1是比较 触须配对引起皮层各层突触的变化。 初步结果表明，颗粒上神经元的变化早于细胞， 任何其他层。两个具体的子目标是测试晶须是否 深层的配对可塑性要求在 皮层的表层，以及可塑性是否取决于 谷氨酸受体机制目标#2是比较响应的极限 VPM丘脑皮质纤维中可能产生的增强 须配对前后的突触。目标#3是分析角色 外丘系感觉调节剂对桶场皮层的影响 的活动之间的非相邻桶时，诱导的晶须配对。 我们将修剪除两个非相邻须以外的所有须，以确定 修改连接的距离限制上的SII和POM损伤 在两个完整胡须的皮质桶之间。目标#4是展示 皮层非感觉神经调质缺失对胡须影响 配对可塑性

Neurons in somatic sensory cortex receive sensory information from the periphery throughout postnatal life. The central hypothesis for the proposed studies is that simple positive biases in the level of ongoing activity from selected whiskers is enough to potentiate their targeted synapses in cortex through glutamate receptor mechansisms. The studies will be carried out in the rat whisker to barrel field cortex pathway because the discrete, non-overlapping receptors in each whisker follide maintain a dear topography to and induding layer Iv of barrel field cortex. In addition, we have demonstrated that the receptive fields of neurons in adult rat barrel field cortex are modified by simply trimming some, but not all, of the whiskers for periods as short as 1 day or up to 30 days. Trimming all but two adjacent whiskers significantly increased the response of cortical neurons to spared whiskers and dramatically diminished the response to cut whiskers. The changes induced by whisker pairing were multifaceted and depend upon cell location in the barrel field cortex, the barrel's relationship to each whisker in the receptive field and how long they were trimmed or spared. Four specific aims are identified to analyze the circuits and mechanisms that support these plastic responses in adult rat cortex: Aim #1 is to compare the rate of change of synapses in each cortical layer induced by whisker pairing. Preliminary results show that supragranular neurons change before cells in any other layer. Two specific sub-goals are to test whether whisker pairing plasticity in the deeper layers requires prior changes in the superficial layers of cortex and whether the plasticity depends on glutamate receptor mechanisms. Aim #2 is to compare the limits of response enhancement that can be generated in the VPM thalamocortical fiber synapses before and after whisker pairing. Aim #3 is to analyze the role of extraIemniscal sensory modulators to barrel field cortex in the spread of activity between non-adjacent barrels when induced by whisker pairing. We will trim all but two non-adjacent whiskers to determine the effect of SII and POm lesions on the distance-limit for modifying connections between cortical barrels of the two intact whiskers. Aim #4 is to show the effect of depletion of non-sensory neuromodulators in cortex on whisker pairing plasticity.