Investigating the shifting architectures of brain and cognition in older adulthood

认知老化的心理学和神经科学研究正在反驳认知老化等于认知能力下降的谬论。认知衰老的真实故事既是一种收获，也是一种损失。随着年龄的增长，知识和生活经验的范围也在不断扩大，这有助于驾驭日常生活的常规和惊喜。何时以及如何利用过去的知识来指导行为会影响老年人在日常生活中推理、解决问题和计划的成功程度。在大脑中，复杂的认知能力，如推理和解决问题，涉及额叶皮质和功能连接区域，共同形成一个“执行网络”。然而，访问一个人的先验知识存储，包括对自己和世界的表征，涉及到一组不同的区域，称为“默认网络”。众所周知，复杂的认知能力在成年后会下降。然而，有证据表明，老年人也许能够利用他们相对丰富的知识和经验来缓解这些衰退。但这在大脑中是如何发生的还没有得到很好的理解。我的工作表明，在复杂的认知任务中，一种可能支持先验知识参与的潜在神经机制是支持复杂认知的大脑网络（即执行网络）和激活存储的知识表征（即默认网络）之间的相互作用。换句话说，增加的默认-执行耦合可能作为一种神经导管，允许先前的知识影响以后生活中的认知功能。我和我的同事把这种现象称为“衰老的默认执行耦合假说”（DECHA）。本研究计划的目的是利用功能神经成像（fMRI）和神经刺激（经颅磁刺激- TMS）方法直接测试DECHA模型。我们将研究与任务性能相关的默认执行耦合模式，其中已知的先验知识会(i)促进或（ii）阻碍任务性能。我们预测DECHA的神经标记（来源于功能磁共振成像和基于神经刺激的研究）将与老年人在先前知识与任务目标相关时更好的任务表现相关，而在与任务目标无关时表现更差。这一提议将质疑一种新的神经认知衰老理论，该理论可能有助于调和与年龄相关的大脑模式和行为变化。如果这些假设得以实现，本研究将确定DECHA作为一种候选神经机制，它更依赖于先前的知识来支持老年人的认知功能。此外，这些发现将提供第一个网络神经科学模型来预测神经认知衰老的全谱，包括认知的增益和损失。

Psychological and neuroscience studies of cognitive aging are disproving the fallacy that cognitive aging equals cognitive decline. The true story of cognitive aging is one of both gains as well as losses. With age comes an expanding repertoire of knowledge and life experience that can help navigate the routines - and the surprises - of daily life. When and how past knowledge is accessed to guide behavior can influence how successfully older adults are able to reason, problem-solve, and plan in their everyday lives. Within the brain, complex cognitive abilities such as reasoning and problem-solving engage frontal cortices and functionally connected regions that together form an `executive network'. However, accessing one's store of prior knowledge, including representations of oneself and the world engages a different set of regions known as the `default network'. It is well known that complex cognitive abilities decline over the adult lifespan. However, evidence is beginning to suggest that older adults may be able to leverage their relatively larger store of knowledge and experiences to mitigate these declines. But how this happens in the brain is not well understood. My work has shown that one potential neural mechanism that may support the engagement of prior knowledge during complex cognitive tasks is the interaction of brain networks supporting complex cognition (i.e. the executive network) and activation of stored knowledge representations (i.e. the default network). In other words, increased default-executive coupling may serve as a neural conduit allowing prior knowledge to influence cognitive functioning in later life. My colleague and I have labeled this the `Default-Executive Coupling Hypothesis of Aging (DECHA). The goal of this research proposal is to directly test the DECHA model using functional neuroimaging (fMRI) and neurostimulation (transcranial magnetic stimulation - TMS) methods. We will examine patterns of default-executive coupling associated with performance on tasks where prior knowledge is known to either (i) facilitate or (ii) hinder task performance. We predict that neural markers of DECHA (derived from fMRI and neurostimulation-based studies) will be associated with better task performance for older adults when prior knowledge is relevant, and worse performance when it is irrelevant, to task goals. This proposal will interrogate a novel theory of neurocognitive aging that may serve to reconcile patterns of age-related brain and behavioural change. If the hypotheses are realized, this research will identify the DECHA as a candidate neural mechanism underlying greater reliance on prior knowledge to support cognitive functioning in older adulthood. Further, these findings would provide the first network neuroscience model to predict the full spectrum of neurocognitive aging, encompassing both cognitive gains and losses.