Dimitriadis Stavros I
Neuroscience and Mental Health Research Institute (NMHI), College of Biomedical and Life Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, Wales, UK.
Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, College of Biomedical and Life Sciences, Cardiff University, Maindy Road, Cardiff CF24 HQ, Wales, UK.
Brain Sci. 2022 Oct 18;12(10):1404. doi: 10.3390/brainsci12101404.
Source activity was extracted from resting-state magnetoencephalography data of 103 subjects aged 18-60 years. The directionality of information flow was computed from the regional time courses using delay symbolic transfer entropy and phase entropy. The analysis yielded a dynamic source connectivity profile, disentangling the direction, strength, and time delay of the underlying causal interactions, producing independent time delays for cross-frequency amplitude-to-amplitude and phase-to-phase coupling. The computation of the dominant intrinsic coupling mode (DoCM) allowed me to estimate the probability distribution of the DoCM independently of phase and amplitude. The results support earlier observations of a posterior-to-anterior information flow for phase dynamics in {α, α, β, γ} and an opposite flow (anterior to posterior) in θ. Amplitude dynamics reveal posterior-to-anterior information flow in {α, α, γ}, a sensory-motor β-oriented pattern, and an anterior-to-posterior pattern in {δ, θ}. The DoCM between intra- and cross-frequency couplings (CFC) are reported here for the first time and independently for amplitude and phase; in both domains {δ, θ, α}, frequencies are the main contributors to DoCM. Finally, a novel brain age index (BAI) is introduced, defined as the ratio of the probability distribution of inter- over intra-frequency couplings. This ratio shows a universal age trajectory: a rapid rise from the end of adolescence, reaching a peak in adulthood, and declining slowly thereafter. The universal pattern is seen in the BAI of each frequency studied and for both amplitude and phase domains. No such universal age dependence was previously reported.
源活动是从103名年龄在18至60岁的受试者的静息态脑磁图数据中提取的。使用延迟符号转移熵和相位熵从区域时间进程中计算信息流的方向性。该分析产生了一个动态源连接性概况，解开了潜在因果相互作用的方向、强度和时间延迟，为跨频率幅度到幅度和相位到相位耦合产生了独立的时间延迟。主导内在耦合模式（DoCM）的计算使我能够独立于相位和幅度估计DoCM的概率分布。结果支持了早期关于{α, α, β, γ}中相位动力学从后向前信息流以及θ中相反方向（从前向后）信息流的观察。幅度动力学揭示了{α, α, γ}中从后向前的信息流、一种感觉运动β导向模式以及{δ, θ}中从前向后的模式。这里首次独立报告了频率内和跨频率耦合（CFC）之间的DoCM，包括幅度和相位方面；在{δ, θ, α}这两个域中，频率都是DoCM的主要贡献因素。最后，引入了一种新的脑龄指数（BAI），定义为频率间耦合与频率内耦合概率分布的比值。该比值呈现出一种普遍的年龄轨迹：从青春期后期迅速上升，在成年期达到峰值，此后缓慢下降。在所研究的每个频率的BAI以及幅度和相位域中都观察到了这种普遍模式。此前没有报道过这种普遍的年龄依赖性。
