Jauny Gwendolyn, Eustache Francis, Hinault Thomas Thierry
Normandie Univ, UNICAEN, PSL Université Paris, EPHE, INSERM, U1077, CHU de Caen, Centre Cyceron, Caen, France.
Front Psychol. 2022 May 25;13:861973. doi: 10.3389/fpsyg.2022.861973. eCollection 2022.
Cognitive reserve and resilience refer to the set of processes allowing the preservation of cognitive performance in the presence of structural and functional brain changes. Investigations of these concepts have provided unique insights into the heterogeneity of cognitive and brain changes associated with aging. Previous work mainly relied on methods benefiting from a high spatial precision but a low temporal resolution, and thus the temporal brain dynamics underlying these concepts remains poorly known. Moreover, while spontaneous fluctuations of neural activity have long been considered as noise, recent work highlights its critical contribution to brain functions. In this study, we synthesized the current state of knowledge from magnetoencephalography (MEG) and electroencephalography (EEG) studies that investigated the contribution of maintenance of neural synchrony, and variability of brain dynamics, to cognitive changes associated with healthy aging and the progression of neurodegenerative disease (such as Alzheimer's disease). The reviewed findings highlight that compensations could be associated with increased synchrony of higher (>10 Hz) frequency bands. Maintenance of young-like synchrony patterns was also observed in healthy older individuals. Both maintenance and compensation appear to be highly related to preserved structural integrity (brain reserve). However, increased synchrony was also found to be deleterious in some cases and reflects neurodegenerative processes. These results provide major elements on the stability or variability of functional networks as well as maintenance of neural synchrony over time, and their association with individual cognitive changes with aging. These findings could provide new and interesting considerations about cognitive reserve, maintenance, and resilience of brain functions and cognition.
认知储备和恢复力是指在大脑结构和功能发生变化时，能够维持认知表现的一系列过程。对这些概念的研究为与衰老相关的认知和大脑变化的异质性提供了独特的见解。以往的研究主要依赖于空间精度高但时间分辨率低的方法，因此这些概念背后的大脑时间动态仍鲜为人知。此外，虽然神经活动的自发波动长期以来被视为噪声，但最近的研究强调了其对大脑功能的关键作用。在本研究中，我们综合了来自脑磁图（MEG）和脑电图（EEG）研究的当前知识状态，这些研究调查了神经同步性的维持以及大脑动态变化对与健康衰老和神经退行性疾病（如阿尔茨海默病）进展相关的认知变化的贡献。综述结果表明，补偿可能与更高（>10Hz）频段同步性的增加有关。在健康的老年人中也观察到了类似年轻人的同步模式的维持。维持和补偿似乎都与保留的结构完整性（大脑储备）高度相关。然而，在某些情况下，同步性增加也被发现是有害的，反映了神经退行性过程。这些结果为功能网络的稳定性或变异性以及神经同步性随时间的维持提供了主要因素，以及它们与个体衰老过程中的认知变化的关联。这些发现可能为认知储备、大脑功能和认知的维持及恢复力提供新的有趣的思考。
