Cognitive training (CT) is an increasingly popular, non-pharmacological intervention for improving cognitive functioning in neurodegenerative diseases and healthy aging. Although meta-analyses support the efficacy of CT in improving cognitive functioning, the neural mechanisms underlying the effects of CT are still unclear. We performed a systematic review of literature in the PubMed, Embase and PsycINFO databases on controlled CT trials (N > 20) in aging and neurodegenerative diseases with pre- and post-training functional MRI outcomes up to November 23rd 2018 (PROSPERO registration number CRD42019103662). Twenty articles were eligible for our systematic review. We distinguished between multi-domain and single-domain CT. CT induced both increases and decreases in task-related functional activation, possibly indicative of an inverted U-shaped curve association between regional brain activity and task performance. Functional connectivity within ‘cognitive’ brain networks was consistently reported to increase after CT while a minority of studies additionally reported increased segregation of frontoparietal and default mode brain networks. Although we acknowledge the large heterogeneity in type of CT, imaging methodology, in-scanner task paradigm and analysis methods between studies, we propose a working model of the effects of CT on brain activity and connectivity in the context of current knowledge on compensatory mechanisms that are associated with aging and neurodegenerative diseases.

中文翻译：

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认知训练对衰老和神经退行性疾病中脑网络活动和连通性的影响：系统评价。

认知训练（CT）是一种越来越受欢迎的非药物干预措施，用于改善神经退行性疾病和健康衰老中的认知功能。尽管荟萃分析支持CT改善认知功能的功效，但尚不清楚CT效应背后的神经机制。我们在对照CT试验中对PubMed，Embase和PsycINFO数据库中的文献进行了系统的综述（N > 20）的衰老和神经退行性疾病，其训练前和训练后的功能性MRI结果截至2018年11月23日（PROSPERO注册号CRD42019103662）。有二十篇文章符合我们的系统评价。我们区分了多域和单域CT。CT引起与任务相关的功能激活的增加和减少，可能表明U倒置区域大脑活动与任务绩效之间的曲线关联。据报道，CT后“认知”脑网络内的功能连通性不断增加，而少数研究还报告了额顶和默认模式脑网络的分离增加。尽管我们承认研究类型之间的CT，成像方法，扫描仪任务范式和分析方法存在巨大的异质性，但我们提出了在当前关于补偿机制的知识背景下CT对脑活动和连接性影响的工作模型。与衰老和神经退行性疾病有关。