Aging, implicit learning, and white matter integrity

描述（由申请人提供）：本研究的主要目的是了解年轻人和老年人内隐学习和白质微观结构之间的关系。研究白质完整性在内隐学习老化中的作用将扩展寿命认知神经科学的新兴文献。内隐学习是在没有意图或意识到所学内容的情况下发生的，直到最近，内隐学习的研究还不如外显学习。这是不幸的，因为对环境规律的敏感性在整个生命中是必不可少的。最近关于内隐学习的认知和神经科学研究表明，有多种形式的内隐学习需要不同的神经基质，但老化研究通常将内隐学习视为单一的。在这里，我们将重点研究序列学习和空间情境学习这两种内隐学习之间的分离，这对于研究大脑-行为关系的年龄变化尤为重要，因为它们需要不同的大脑系统，这些系统受到健康衰老的不同影响。影像和患者研究表明，内隐序列学习依赖于额叶-纹状体-小脑网络，而内隐空间背景学习则由内侧颞叶介导。该实验将首次在同一组参与者中使用扩散张量成像（DTI）来检测连接神经网络的白质的完整性（具体目标2）。DTI的研究表明，随着年龄的增长，白质的完整性会下降，尤其是在大脑前部区域，这可能会影响健康老年人的认知表现。在本研究中，预计老年人内隐序列学习受损，但内隐空间语境学习不受损（Specific Aim 1），这一发现与健康衰老对额纹状体系统的影响大于内侧颞叶的观点一致。多元回归分析还将检验年龄相关的大脑变化是否会影响这两种内隐学习任务与相应神经网络的白质完整性之间的关系，这是第一个利用内隐学习任务评估大脑-行为关系的年龄差异的研究，在这些任务中，行为表现既会随着年龄的增长而受损，也不会受到影响（具体目标3）。本研究结果与成功衰老有关。内隐学习通过使人们适应变化（即新的环境、人和技术）来促进独立生活，并有助于从事故或中风后的脑损伤中恢复。因此，确定内隐学习形式及其潜在的白质连接之间与年龄相关的稳定性对于旨在最大限度地成功老化和脑损伤后恢复的训练计划非常重要。

DESCRIPTION (provided by applicant): The primary goal of the proposed research is to understand the relationship between implicit learning and white matter microstructure in younger and older adults. Examining the role of white matter integrity in the aging of implicit learning will extend the emerging literature on lifespan cognitive neuroscience. Implicit learning occurs without intent or awareness of what has been learned, and until recently it has been studied less that its explicit counterpart. This is unfortunate because sensitivity to regularities in the environment is essential throughout life. Recent cognitive and neuroscience research on implicit learning indicates that there are multiple forms of implicit learning that call on different neural substrates, but aging research usually treats implicit learning as though it is unitary. Here, we will focus on a dissociation between two types of implicit learning, sequence learning and spatial context learning, that are especially important for studying age changes in brain-behavior relationships because they call on different brain systems that are differentially affected by healthy aging. Imaging and patient studies suggest that implicit sequence learning relies on a frontal-striatal-cerebellar network, and implicit spatial context learning is mediated by the medial temporal lobes. The proposed experiment will be the first to examine this dissociation in the same group of participants using diffusion tensor imaging (DTI) to measure the integrity of white matter that connects neural networks (Specific Aim 2). DTI research has shown that white matter integrity declines with aging, especially in anterior brain regions, which may affect cognitive performance in healthy older adults. In this study, older adults are expected to be impaired at implicit sequence learning, but not implicit spatial context learning (Specific Aim 1), a finding consistent with the view that healthy aging affects the frontal-striatal system more than the medial temporal lobes. Multiple regression analyses will also examine if age-related brain changes affect the relationships between these two implicit learning tasks and white matter integrity from their corresponding neural networks, being the first to-assess age differences in brain-behavior relationships using implicit learning tasks in which behavioral performance is both impaired and spared with aging (Specific Aim 3). Results from this study are relevant to successful aging. Implicit learning promotes independent living by enabling people to adapt to change (i.e. new settings, people, and technologies), and can facilitate recovery from brain damage following accidents or strokes. Thus, identifying age-related stability between forms of implicit learning and their underlying white matter connectivity is important for training programs aimed at maximizing successful aging and recovery after brain damage.