Neural basis of aging and implicit learning

描述（由申请人提供）：拟议研究的主要目标是确定年轻人和老年人在内隐学习的神经过程中的差异。内隐学习是一种无意识的信息获取，它发生在没有意图或意识到已经学到的东西的情况下。衰老的研究主要集中在外显学习上，因此，健康的年龄相关的大脑变化对内隐学习的影响在很大程度上被忽视，限制了衰老的认知神经科学的范围。这是不幸的，因为对环境中有害物质的敏感性使人们能够更有效地预测和处理未来事件，这种能力在整个生命周期中都至关重要。内隐学习是否会随着健康的老龄化而下降尚不清楚，尽管当人们需要学习的刺激很复杂时，以及当人们接受长期训练时，会观察到与年龄相关的缺陷。在这里，24名年轻人和24名老年人将接受功能性磁共振成像（fMRI），同时他们学习和练习一种复杂的概率顺序内隐技能。据预测，老年人在早期训练中会像年轻人一样学习，但随着更多的练习，与年龄相关的缺陷将出现（具体目标1），使这项拟议的研究成为第一个评估内隐学习过程中大脑活动的研究。早期内隐学习和实际内隐学习之间的分离对于认知神经科学很重要，原因有二。首先，以前的成像研究表明，随着学习的进展，技能学习涉及不同的大脑区域;早期学习涉及内侧颞叶（即海马），后来，实践学习涉及纹状体（即尾状核）。这项研究将是第一个研究这些相同的学习激活关系是否是内隐学习的特征（具体目标2），通过使用一个范式，其中可以排除外显学习。第二，早期学习和实践学习的大脑区域在受年龄影响的程度上有所不同。在拟议的研究中，功能连接分析将检查大脑活动与早期与实践学习之间的关系，以评估神经募集中与年龄相关的差异如何随实践水平而变化（具体目标3）。据预测，早期内隐学习将激活海马或MTL网络在两个年龄组，反映了相对保存的MTL在健康老龄化。在实践学习中，年轻的成年人将在尾侧或纹状体网络中表现出激活。由于衰老相关的衰退，尾状核激活在老年人中将不占主导地位;老年人将依赖于他们完整的学习相关脑区，包括海马体和周围的MTL。这些发现与健康老龄化对纹状体的影响大于MTL的观点一致。 公共卫生相关性：对微妙的连续事件的内隐学习可以通过支持认知灵活性来促进独立生活，并可以帮助老年人预测和适应不断变化的世界（即新的环境，人和技术）。因此，建立完整的内隐学习与受损的内隐学习可能有助于设计教育计划或加强康复工作，因为这种训练可以利用老年人的剩余能力，并补偿那些已经下降的能力，以最大限度地成功老龄化。定义大脑功能的正常年龄差异也可能有助于早期发现常见的年龄相关疾病，如阿尔茨海默氏症和帕金森氏症。

DESCRIPTION (provided by applicant): The primary goal of the proposed research is to identify differences between young and old adults in the neural processes underlying implicit learning. Implicit learning is the non-conscious acquisition of information that occurs without intent or awareness of what has been learned. Research in aging has mostly focused on explicit learning, and thus, the effects of healthy age-related brain changes on implicit learning have remained largely ignored, limiting the scope of the cognitive neuroscience of aging. This is unfortunate because sensitivity to regularities in the environment makes it possible to anticipate and process future events more effectively and this ability is essential throughout the lifespan. Whether implicit learning declines with healthy aging is unclear, though age-related deficits are observed when the stimuli to be learned are complex and when people are given extended training. Here, 24 young and 24 old adults will undergo functional magnetic resonance imaging (fMRI) while they learn and practice a complex, probabilistic sequential implicit skill. It is predicted that old adults will learn as well as the young early in training, but with more practice, age-related deficits will emerge (Specific Aim 1), making this proposed study the first to assess brain activity during implicit learning when behavior is both spared and impaired. The dissociation between early and practiced implicit learning is important to cognitive neuroscience for two reasons. First, previous imaging studies suggest that skill learning involves different brain regions as learning progresses; early learning involves the medial temporal lobes (i.e. hippocampus) and later, practiced learning involves the striatum (i.e. caudate). The proposed study will be among the first to examine whether these same learning-activation relationships are characteristic of implicit learning (Specific Aim 2), by using a paradigm in which explicit learning can be ruled out. Second, the brain regions underlying early and practiced learning differ in the extent to which they are compromised by aging. In the proposed study, functional connectivity analyses will examine relationships between brain activity and early versus practiced learning to assess how age-related differences in neural recruitment vary with the level of practice (Specific Aim 3). It is predicted that early implicit learning will activate the hippocampus or MTL networks in both age groups, reflecting the relatively preserved MTL in healthy aging. In practiced learning, younger adults will demonstrate activation in caudal or striatal networks. Due to aging- related declines, caudate activation will not be as dominant in older adults; older adults will rely on their intact learning-related brain regions, including the hippocampus and surrounding MTL. These findings would be consistent with the view that healthy aging affects the striatum more than the MTL. PUBLIC HEALTH RELEVANCE: Implicit learning of subtle sequential events can promote independent living by supporting cognitive flexibility and can help older adults anticipate and adapt to an ever-changing world (i.e. new settings, people, and technologies). Thus, establishing the kinds of implicit learning that are intact versus impaired may be useful for designing educational programs or enhancing rehabilitation efforts, because such training could take advantage of the older persons' spared capacities and compensate for those that have declined in order to maximize successful aging. Defining normal age differences in brain function may also help in early detection of common age-related diseases, such as Alzheimer's and Parkinson's.