Aging is characterized by a decline of cognitive control. In semantic cognition, this leads to the paradox that older adults usually show poorer task performance than young adults despite their greater semantic knowledge. So far, the underlying neural changes of these behavioral differences are poorly understood. In the current neuroimaging study, we investigated the interaction of domain-specific and domain-general networks during verbal semantic fluency in young and older adults. Across age groups, task processing was characterized by a strong positive integration within the multiple-demand as well as between the multiple-demand and the default mode network during semantic fluency. However, the behavioral relevance of strengthened connectivity differed between groups: While within-network functional connectivity in both networks predicted greater efficiency in semantic fluency in young adults, it was associated with slower performance in older adults. Moreover, only young adults profited from connectivity between networks for their semantic memory performance. Our results suggest that the functional coupling of usually anticorrelated networks is critical for successful task processing, independent of age, when access to semantic memory is required. Furthermore, our findings lend novel support to the notion of reduced efficiency in the aging brain due to neural dedifferentiation in semantic cognition.

中文翻译：

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领域通用网络对语义认知的年龄依赖性贡献

衰老的特点是认知控制能力下降。在语义认知中，这导致了一个悖论，即老年人通常表现出比年轻人更差的任务表现，尽管他们有更多的语义知识。到目前为止，人们对这些行为差异的潜在神经变化知之甚少。在当前的神经影像学研究中，我们调查了年轻人和老年人语言语义流畅期间特定领域和一般领域网络的相互作用。跨年龄组，任务处理的特点是在语义流畅性期间，多需求内以及多需求与默认模式网络之间存在强烈的正向整合。然而，加强连通性的行为相关性在各组之间有所不同：虽然两个网络中的网络内功能连接预测年轻人的语义流畅性效率更高，但它与老年人的表现较慢有关。此外，只有年轻人才能从网络之间的连接中获益，因为他们的语义记忆表现。我们的结果表明，当需要访问语义记忆时，通常反相关网络的功能耦合对于成功的任务处理至关重要，与年龄无关。此外，我们的研究结果为由于语义认知中的神经去分化导致衰老大脑效率降低的概念提供了新的支持。只有年轻人才能从网络之间的连接中获益，因为他们的语义记忆表现。我们的研究结果表明，当需要访问语义记忆时，通常反相关网络的功能耦合对于成功的任务处理至关重要，与年龄无关。此外，我们的研究结果为由于语义认知中的神经去分化导致衰老大脑效率降低的概念提供了新的支持。只有年轻人才能从网络之间的连接中获益，因为他们的语义记忆表现。我们的研究结果表明，当需要访问语义记忆时，通常反相关网络的功能耦合对于成功的任务处理至关重要，与年龄无关。此外，我们的研究结果为由于语义认知中的神经去分化导致衰老大脑效率降低的概念提供了新的支持。