用新方法分析大脑电波相位关系,可处理上千通道数据。
Torus Graphs for Large Scale Neural Phase Analysis

- 基于环面图模型,用随机得分匹配提升计算效率
- 在1860个频段-相位特征上实现动态相位耦合建模
- 适合研究睡眠与清醒状态下的脑区相位交互
脑电图(EEG)和局部场电位(LFP)中的振荡信号通过相位关系协调脑区间通信。现代记录可捕获数百个通道及多个频率分量,但传统相位分析仅限于少量变量。环面图(Torus Graph, TG)模型是一种基于指数族分布的相位结构推断方法,其单变量和成对势函数推广了冯·米塞斯分布,能刻画振荡间的合理依赖关系,但仅支持静态、无向依赖,且因得分匹配推理复杂度为 𝒪(d⁶),受限于约100个变量。本文提出一种随机得分匹配方法,将每轮迭代成本降至 𝒪(d²),使模型可扩展至数千变量。该可扩展基础支持对1,860个频率-相位特征的多电极LFP数据建模,并实现了两个此前无法用TG或经典圆统计方法实现的拓展:(i) 环面图隐马尔可夫模型,捕捉睡眠中纺锤波相关状态下的相位耦合变化;(ii) 自回归环面图,通过转移熵估计推断方向性相互作用。应用于LFP数据,揭示了清醒与非快速眼动睡眠状态下脑区间相位交互模式的动态差异。整体框架实现了跨脑区与认知状态的大规模、动态及定向相位关系系统分析。
原文摘要 · Abstract (English)
Oscillatory neural signals such as electroencephalography (EEG) and local field potentials (LFPs) show phase relationships that coordinate communication across brain regions. Modern recordings capture hundreds of channels across many frequency bins, yet standard phase analyses are restricted to only a few variables. The Torus Graph (TG) model, an exponential-family distribution over phases whose univariate and pairwise potentials generalize von Mises distributions, infers principled structure among oscillations but models only static, undirected dependencies and is limited to $\sim \! 100$ variables because its score matching inference scales as $\mathcal{O}(d^{6})$. We introduce a stochastic score matching procedure that reduces the per-iteration cost to $\mathcal{O}(d^{2})$, enabling inference on datasets with thousands of variables. This scalable foundation supports analyses of 1,860 frequency-phase features from multi-electrode LFPs and enables two extensions previously inaccessible to TGs or classical circular statistics: (i) a TG Hidden Markov Model capturing state-dependent phase-coupling changes (e.g., spindle-related states during sleep) and (ii) an autoregressive TG inferring directional interactions via transfer-entropy estimation. Applied to LFP recordings, these models reveal state-dependent phase-interaction patterns between wakefulness and NREM sleep. Together, they enable systematic, large-scale mapping of dynamic and directional phase relationships across brain and cognitive states.
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