Testing the Criticality Hypothesis in Local Cortical Circuits

皮质神经元是如何共同作用来处理信息的？最近在脑组织样本和完整大脑中进行的多电极记录支持了一个新的假设，表明局部皮质网络在一个临界点附近自组织运作。在这一点上，所有空间和时间尺度上的相互作用都可能发生，并且在所有规模上产生雪崩的神经活动，导致近似幂律分布。非常通用的神经网络模型表明，此时信息处理将是最佳的。这一“临界假设”对大脑皮层回路的计算具有重要意义，并最终影响到人类健康。尽管这一假设具有潜在的重要性，但它尚未在由100个或更多突触连接的神经元组成的局部皮层网络中得到验证。以前的工作依赖于局部场电位记录，这并不能揭示产生信号的单个神经元的数量或位置。以前的工作也依赖于相对较少的（约60-100个）宽间隔的记录位点，这不足以对突触连接的神经元群体进行充分采样。在这里，PI将记录512个紧密间隔的电极，使我们能够监测数百个神经元的尖峰行为，其中许多神经元预计会共享突触连接。PI将对临界假设进行测试，这将使他第一次确定皮质神经元网络是否临界。科学教育和推广是这项建议的另一个重要组成部分。PI将让数千名来自经济落后地区的儿童参与到WonderLab互动展览的开发和使用中来。WonderLab是一家受欢迎的当地科学博物馆，面向k -中学的儿童。这个展览是基于脑电图（EEG）记录，并将显示儿童的脑电波，允许他们通过生物反馈来修改这些电波。这次展览将在每年接待78000名游客的WonderLab博物馆展出。WonderLab被《家长》杂志评为“美国25大科学中心”之一。

How do cortical neurons collectively interact to process information? A new hypothesis, supported by recent multielectrode recordings in brain tissue samples and in the intact brain, suggests that local cortical networks self-organize to operate near a critical point. At this point, interactions across all spatial and temporal scales can occur, and avalanches of neural activity are generated at all sizes, resulting in approximately power law distributions. Very generic neural network models suggest that information processing will be optimal at this point. This "criticality hypothesis" has significant implications for computation in cortical circuits, and ultimately, for human health. Despite the potential importance of this hypothesis, it has remained untested in local cortical networks consisting of 100 or more synaptically connected neurons. Previous work has relied on local field potential recordings, which do not reveal the number or location of individual neurons generating signals. Previous work also has relied on relatively few (~60-100) broadly-spaced recording sites, which are insufficient to adequately sample a population of synaptically connected neurons. Here, the PI will record from 512 closely spaced electrodes, allowing us to monitor the spiking behavior of hundreds of neurons, many of which are expected to share synaptic connections. The tests the PI will perform of the criticality hypothesis will allow him, for the first time, to determine if networks of cortical neurons are critical or not. Scientific education and outreach is another vital component of this proposal. The PI will engage thousands of children from economically disadvantaged areas in the development and use of an interactive exhibit for WonderLab, a popular local science museum for K-middle school children. This exhibit is based on electroencephalogram (EEG) recordings and will display children's brain waves, allowing them to modify these waves by biofeedback. This exhibit will be placed in WonderLab museum, which serves 78,000 visitors each year. WonderLab has been named by Parent's magazine as one of the "Top 25 Science Centers in the United States."