Table_1_Variation in the distribution of large-scale spatiotemporal patterns of activity across brain states.DOCX

A few large-scale spatiotemporal patterns of brain activity (quasiperiodic patterns or QPPs) account for most of the spatial structure observed in resting state functional magnetic resonance imaging (rs-fMRI). The QPPs capture well-known features such as the evolution of the global signal and the alternating dominance of the default mode and task positive networks. These widespread patterns of activity have plausible ties to neuromodulatory input that mediates changes in nonlocalized processes, including arousal and attention. To determine whether QPPs exhibit variations across brain conditions, the relative magnitude and distribution of the three strongest QPPs were examined in two scenarios. First, in data from the Human Connectome Project, the relative incidence and magnitude of the QPPs was examined over the course of the scan, under the hypothesis that increasing drowsiness would shift the expression of the QPPs over time. Second, using rs-fMRI in rats obtained with a novel approach that minimizes noise, the relative incidence and magnitude of the QPPs was examined under three different anesthetic conditions expected to create distinct types of brain activity. The results indicate that both the distribution of QPPs and their magnitude changes with brain state, evidence of the sensitivity of these large-scale patterns to widespread changes linked to alterations in brain conditions.

大脑活动的若干大型时空模式（准周期模式，quasiperiodic patterns，简称QPPs）可解释静息态功能磁共振成像（resting state functional magnetic resonance imaging，简称rs-fMRI）中观测到的绝大多数空间结构。这类QPPs能够精准捕捉诸多经典特征，例如全局信号的动态演化过程，以及默认模式网络与任务正性网络的交替主导现象。此类广泛分布的活动模式，与介导觉醒、注意力等非局部过程变化的神经调节输入存在合理关联。
为探究QPPs是否会随脑状态产生差异，研究在两种场景下对三种最强QPPs的相对幅度与分布展开了分析。其一，基于人类连接组项目（Human Connectome Project）的数据集，在扫描全程中考察QPPs的相对发生率与幅度，其核心假设为：嗜睡程度的提升会随时间推移改变QPPs的表达模式。其二，采用一种可最大程度抑制噪声的新型方法获取大鼠rs-fMRI数据，在三种预期会诱导不同类型脑活动的麻醉状态下，考察QPPs的相对发生率与幅度。
研究结果显示，QPPs的分布及其幅度均会随脑状态发生改变，这一发现证实这类大型时空模式对与脑状态改变相关的广泛生理变化具有敏感性。