2007 — 2008 |
Bennett, Ilana Jacqueline |
F31Activity Code Description: To provide predoctoral individuals with supervised research training in specified health and health-related areas leading toward the research degree (e.g., Ph.D.). |
Aging, Implicit Learning, and White Matter Integrity
[unreadable] 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. [unreadable] [unreadable] [unreadable]
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0.956 |
2010 |
Bennett, Ilana Jacqueline |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
The Role of White Matter Integrity in the Neural Efficiency Hypothesis of Cogniti @ University of Texas Dallas
DESCRIPTION (provided by applicant): The primary goal of the proposed research is to further understand the neurobiological basis of cognitive aging. Neural substrates underlying age-related working memory (WM) differences will be examined using the framework of the neural efficiency hypotheses, which states that reduced efficiency of cortical functioning underlies slower speed of processing in older versus younger adults, which in turn mediates age- related cognitive declines. The proposed research will advance this hypothesis using diffusion tensor imaging (DTI) in combination with functional magnetic resonance imaging (fMRI) to assess the contribution of white matter integrity to neural efficiency. Age-related slowing has been proposed to account for cognitive aging, including age-related WM declines. However, the neural basis of this effect has not been systematically examined. FMRI research has shown that prefrontal (PFC) and parietal cortex mediate WM performance, and that activity in these regions is modulated by WM performance speed and processing speed. We propose that the relationship between processing speed and the magnitude of neural activity may reflect efficiency of neural functioning, which may underlie age group differences in WM. The proposed experiment will be the first to directly test whether individual differences in neural efficiency, measured as processing speed-related PFC activity, mediates WM declines in aging (Specific Aim 1). The neural efficiency hypothesis further proposes that age-related neural efficiency declines may be due to age group differences in underlying brain structure, such as integrity of white matter connections between task-relevant brain regions. DTI research has shown that integrity of frontal white matter declines with aging, and is associated with impaired processing speed and WM in older versus younger adults. The proposed study will be the first to examine whether age group differences in integrity of task-relevant frontal-parietal tracts relates to neural efficiency, and whether this explains age group differences in WM performance (Specific Aim 2). These long-range direct connections may be more susceptible to age-related declines in integrity, which may lead to increased dependence on indirect connections (i.e., frontal-thalamus-parietal) for optimal task performance. Therefore, this study will also assess relationships among indirect tract integrity, neural efficiency, and WM performance in aging (Specific Aim 3). Results from this study will contribute to fostering successful aging. WM is integral to a variety of everyday skills including reasoning, language comprehension, and mental calculations. Identifying functional and structural neural mechanisms underlying optimal performance will inform cognitive training and pharmacological treatment programs aimed at maximizing cognitive functioning in old age. This goal is becoming increasingly important as the number of older adults in our population steadily rises. PUBLIC HEALTH RELEVANCE: Results from this study are relevant to successful aging. Working memory promotes independent living by enabling people to perform a variety of everyday skills including reasoning, language comprehension, and mental calculations. Thus, identifying the neural mechanisms underlying optimal performance is important for cognitive training and pharmacological treatment programs aimed at maximizing cognitive functioning in old age. This goal is becoming increasingly important as the number of older adults in our population steadily rises.
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0.959 |