ANALYSIS OF RECEPTIVE FIELDS OF LAYER LV

提议的实验的目标是了解 在大脑中控制感觉信息处理的机制 成年哺乳动物的大脑皮层。阿姆斯特朗之前的研究结果- 詹姆斯和福克斯，包括在这项提案中，已经量化了 桶状野皮质内皮质神经元的感受野 通过测量它们的反应来代表我的触觉 到振动挠度。由此得出的一个重要结论 研究表明，反应最强的第四层神经元 概率(每个刺激超过50次的2个或更多尖峰) 刺激他们适当的触觉也会在短时间内起作用 延迟(&lt；10毫秒)。除了最好的响应(此处 第四层神经元也称为中心感受野或CRF 表现出较低的概率，较长的开始放电潜伏期 额外的胡须数量(兴奋时平均为2.6 环绕或SRF)。两个假设将由拟议的 实验。其一是高概率(2个尖峰/刺激) +筒状野外单元的短潜伏期(&lt；10毫秒)响应 触觉偏转是通过VB途径产生的 皮层，而概率较低(1个或更少的刺激峰/刺激) +通过以下方式生成延迟更长(&gt；10毫秒)的响应 脊髓V-POM通路或通过皮质连接； 是通过大脑皮质还是通过大脑皮质内的短连接 或者两者兼而有之。第二种假设是基于观察到的 SI细胞活动中的某些成分依赖于 需要激活酸性氨基酸受体，特别是 NMDA受体。NMDA受体已被证明是 自发爆发活动的产生，但不是为了 感觉输入激活大脑皮层神经元。在此基础上 对NMDA受体的不同依赖，我们预测 这些受体是产生周围环境所必需的，但 不是第四层皮质细胞感受器的中心成分 现场响应。支持这些假说的证据将 提供了对潜在的神经回路的新见解 皮层神经元的感受野，并可以识别重要的 特定与非特定之间的功能相互作用 可能调节强度的丘脑皮质投射系统 感觉皮质中的突触。

The goal of the proposed experiments is to understand the mechanisms that control sensory information processing in the cerebral cortex of adults mammals. Previous results by Armstrong- James and Fox, included in this proposal, have quantified the receptive field of cortical neurons in the barrel field cortex representing the mystacial vibrissae by measuring their response to vibrissal deflections. An important conclusion from these studies is that layer IV neurons that responded with the highest probability (2 or more spikes per stimulus over 50 repetitions) to stimulation of their appropriate vibrissa also responded at short latencies (<10 msec). In addition to the best response (here called the Center Receptive Field or CRF), layer IV neurons also showed lower probability, longer latency to onset of discharge to an additional number of whiskers (2.6 on average in the Excitatory Surround or SRF). Two hypothesis will be tested by the proposed experiments. One is that the high probability (>2 spikes/stimulus) + short latency (<10 msec) responses of barrel field cells to vibrissae deflection are generated through the VB pathway to cortex, while the lower probability (1 or fewer spikes/stimulus) + longer latency (>10 msec) responses are generated either through the spinal V to POM pathway or through corticocortical connections; either through SII cortex or short intracortical connections within SI or both. The second hypothesis is based on the observation that some components within SI cell activity depend upon mechanisms that require activation of acidic amino acid receptors, specifically the NMDA receptors. NMDA receptors have been shown to be essential for the generation of spontaneous burst activity, but not for the activation of cortical neurons by sensory inputs. Based on this differential dependence on the NMDA receptors, we predict that these receptors will be necessary for generating the surround, but not the center component of the layer IV cortical cell receptive field responses. Evidence supporting these hypotheses would provide new insights into the neural circuitry underlying the receptive fields of cortical neurons and could identify important functional interactions between the specific and the nonspecific thalamocortical projection systems that may regulate the strength of synapses in sensory cortex.