Neuronal avalanches in the neocortex

新皮质中的神经元雪崩

• 批准号: 8745708
• 负责人: Dietmar Plenz
• 金额: $ 153.85万
• 依托单位: NATIONAL INSTITUTE OF MENTAL HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8745708
• 关键词: Alzheimer' s Disease; American; Animals; Behavior; Books; Brain; Cereals; Clinical; Cognition; Collaborations; Comparative Study; Complex; Cortical Synchronization; Data; Development; Diagnosis; Disease; Epilepsy; Equilibrium; Esthesia; Functional Magnetic Resonance Imaging; Functional disorder; Generations; Goals; Grouping; Heating; Human; In Vitro; International; Intramural Research Program; Laws; Lead; Learning; Life; Link; Macaca; Magnetoencephalography; Measures; Membrane Potentials; Memory; Microelectrodes; Monkeys; Neocortex; Neurons; Neurosciences; Patients; Performance; Phase; Phase Transition; Physics; Physiological; Predisposition; Preparation; Process; Publications; Published Comment; Publishing; Regulation; Reporting; Research; Research Infrastructure; Rest; Rodent; Role; Schizophrenia; Societies; Solid; Solutions; System; Technology; Temperature; Text; Thermodynamics; Time; United States National Institutes of Health; Universities; Work; abstracting; awake; base; cell assembly; density; human subject; in vivo; information processing; posters; premature; relating to nervous system; research study; sensor; spatiotemporal; symposium; theories; working group

1. We identified for the first time that neuronal avalanches form the organization of the normal human brain at rest. This study involved magentoencephalography recordings from more than 100 normal human subjects collected at 2 different MEG centers (NIH and Cambridge, UK) using two different MEG systems. This comparative study establishes the platform to link deviations from neuronal avalanches to brain dysfunction as found in e.g. in patients suffering from schizophrenia or Alzheimers disease (Shriki et al., 2013). Abstract: Neuronal Avalanches in the Resting MEG of the Human Brain What constitutes normal cortical dynamics in healthy human subjects is a major question in systems neuroscience. Numerous in vitro and in vivo animal studies have shown that ongoing or resting cortical dynamics are characterized by cascades of activity across many spatial scales, termed neuronal avalanches. In experiment and theory, avalanche dynamics are identified by two measures (1) a power law in the size distribution of activity cascades, with an exponent of 3/2 and (2) a branching parameter of the critical value of 1, reflecting balanced propagation of activity at the border of premature termination and potential blow up. Here we analyzed resting-state brain activity recorded using non-invasive magnetoencephalography (MEG) from 124 healthy human subjects and two different MEG facilities using different sensor technologies. We identified large deflections at single MEG sensors and combined them into spatiotemporal cascades on the sensor array, using multiple timescales. Cascade-size distributions obeyed power laws. For the timescale at which the branching parameter was close to 1, the power law exponent was 3/2. This relationship was robust to scaling and coarse-graining of the sensor array. It was absent in phase-shuffled controls with the same power spectrum or empty-scanner data. Our results demonstrate that normal cortical activity in healthy human subjects at rest organizes as neuronal avalanches and is well described by a critical branching process. Theory and experiment have shown that such critical, scale-free dynamics optimize information processing. Thus, our findings imply that the human brain attains an optimal dynamical regime for information processing. 2. Neuronal avalanches identify critical brain dynamics at which several aspects of information processing are optimized as demonstrated in our previous work. Several classes of critical systems have been identified based on the precise critical exponents that control a systems performance at criticality. We identified the critical exponents for the mammalian brain for the first time and suggest that the brain resides in its own universality class. This comparative study was performed on resting activity in the awake macaque monkey using local field potentials and resting activity in normal human subjects using magnetoencephalography (Yu et al., 2013). Abstract: Universal Organization of Resting Brain Activity at the Thermodynamic Critical Point Thermodynamic criticality describes emergent phenomena in a wide variety of complex systems. In the mammalian cortex, one type of complex dynamics that spontaneously emerges from neuronal interactions has been characterized as neuronal avalanches. Several aspects of neuronal avalanches such as their size and life time distributions are described by power laws with unique exponents indicative of an underlying critical branching process that governs avalanche formation. Here, we show that neuronal avalanches also reflect an organization of brain dynamics close to a thermodynamic critical point. We recorded spontaneous cortical activity in monkeys and humans at rest using high-density intracranial microelectrode arrays and magnetoencephalography, respectively. By numerically changing a control parameter equivalent to thermodynamic temperature, we observed typical critical behavior in cortical activities near the actual physiological condition, including the phase transition of an order parameter, as well as the divergence of susceptibility and specific heat. Finite-size scaling of these quantities allowed us to derive robust critical exponents highly consistent across monkey and humans that uncover a distinct, yet universal organization of brain dynamics. Our results demonstrate that normal brain dynamics at rest resides near or at criticality which maximizes several aspects of information processing such as input sensitivity and dynamic range. 3. Neuronal avalanches are increasingly recognized to be important for cortex function. My Section took the lead in organizing the first conference on Criticality in Neural Systems in collaboration with Ernst Niebur, Johns Hopkins University. In April 2012, the 2-day conference took place on the NIH campus in Bethesda at the Natcher Conference center with about 100 attendees and featured 19 international and national speakers and posters. Since then, a book with about 22 chapters and international authors, most of who presented at the conference, has been assembled and recently sent to the Publisher Wiley-VCH where it will be published in autumn 2013/spring 2014. The book covers all major aspects of criticality in the brain and is on track to become a standard text book for a rapidly increasing field of critical phenomena in the brain. Besides being the main editor, my Section has contributed 4 chapters covering our major accomplishments demonstrating criticality in the brain from in vitro preparations to the awake animals and normal human subjects. 4. Our work on criticality in the brain is increasingly recognized and results in numerous invited comments on other groups working on criticality in the brain. This is demonstrated by a recent invited Commentary in Physics Highlights, the highest commentary level of the American Physics Society, on critical phenomenal demonstrated in the human brain using fMRI (Plenz 2013).

1. 我们首次发现神经元雪崩形成了正常人脑在休息时的组织结构。 这项研究涉及从 2 个不同的 MEG 中心（NIH 和英国剑桥）使用两种不同的 MEG 系统收集的 100 多名正常人类受试者的磁脑磁图记录。 这项比较研究建立了一个平台，将神经元雪崩的偏差与大脑功能障碍联系起来，例如在患有精神分裂症或阿尔茨海默病的患者（Shriki et al., 2013）。 抽象的： 人脑静息 MEG 中的神经元雪崩 健康人类受试者正常皮质动力学的构成是什么是系统神经科学的一个主要问题。大量的体外和体内动物研究表明，持续或静息的皮质动力学的特征是跨多个空间尺度的级联活动，称为神经元雪崩。 在实验和理论中，雪崩动力学通过两种措施来识别：（1）活动级联大小分布的幂律，指数为 3/2；（2）临界值为 1 的分支参数，反映活动在过早终止和潜在爆炸边界处的平衡传播。 在这里，我们分析了 124 名健康受试者和使用不同传感器技术的两个不同 MEG 设施使用非侵入性脑磁图 (MEG) 记录的静息态大脑活动。 我们识别出单个 MEG 传感器的大偏转，并使用多个时间尺度将它们组合成传感器阵列上的时空级联。 级联大小的分布遵循幂律。 对于分支参数接近 1 的时间尺度，幂律指数为 3/2。 这种关系对于传感器阵列的缩放和粗粒度来说是稳健的。它在具有相同功率谱或空扫描仪数据的相改组控制中不存在。 我们的结果表明，健康人类受试者在休息时的正常皮质活动会组织为神经元雪崩，并且可以通过关键的分支过程得到很好的描述。 理论和实验表明，这种关键的、无标度的动态优化了信息处理。 因此，我们的研究结果意味着人脑获得了信息处理的最佳动态状态。 2. 神经元雪崩识别关键的大脑动态，在该动态中信息处理的多个方面得到优化，如我们之前的工作所证明的。 已经根据控制关键系统性能的精确关键指数来识别几类关键系统。 我们首次确定了哺乳动物大脑的关键指数，并表明大脑存在于其自己的普遍性类别中。 这项比较研究是使用局部场电位对清醒猕猴的静息活动和使用脑磁图对正常人类受试者的静息活动进行的（Yu et al., 2013）。 抽象的： 热力学临界点静息大脑活动的普遍组织 热力学临界性描述了各种复杂系统中的涌现现象。 在哺乳动物皮层中，神经元相互作用自发产生的一种复杂动力学被称为神经元雪崩。神经元雪崩的几个方面，例如它们的大小和寿命分布，由幂律描述，具有独特的指数，指示控制雪崩形成的潜在关键分支过程。 在这里，我们表明神经元雪崩也反映了接近热力学临界点的大脑动力学组织。 我们分别使用高密度颅内微电极阵列和脑磁图记录了猴子和人类在休息时的自发皮质活动。 通过数值改变相当于热力学温度的控制参数，我们观察到接近实际生理条件的皮层活动的典型临界行为，包括有序参数的相变，以及磁化率和比热的发散。 这些量的有限尺度缩放使我们能够得出在猴子和人类之间高度一致的稳健临界指数，从而揭示了大脑动力学的独特但普遍的组织。 我们的结果表明，休息时的正常大脑动态处于接近或处于临界状态，这最大化了信息处理的几个方面，例如输入灵敏度和动态范围。 3. 人们越来越认识到神经元雪崩对于皮层功能很重要。 我的部门与约翰·霍普金斯大学的恩斯特·尼伯 (Ernst Niebur) 合作，牵头组织了第一届神经系统临界性会议。 2012 年 4 月，为期 2 天的会议在 NIH 贝塞斯达校区的 Natcher 会议中心举行，约有 100 名与会者，其中有 19 名国际和国内演讲者和海报。 此后，一本由约 22 章和国际作者组成的书（其中大部分在会议上发言）已经完成，最近已发送给出版商 Wiley-VCH，该书将于 2013 年秋季/2014 年春季出版。这本书涵盖了大脑临界性的所有主要方面，并有望成为快速增长的大脑临界现象领域的标准教科书。 除了作为主编之外，我的部门还贡献了 4 章内容，涵盖了我们的主要成就，证明了从体外准备到清醒动物和正常人类受试者大脑的重要性。 4. 我们在大脑临界性方面的工作越来越受到认可，并导致其他研究大脑临界性的小组受到许多邀请发表评论。最近受邀发表的《物理亮点评论》（美国物理学会的最高评论级别）就证明了这一点，该评论关于使用功能磁共振成像在人脑中展示的关键现象（Plenz 2013）。