School of Public Health

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

Note: Prior to July 1, 2007, the School of Public Health was named the College of Health & Human Performance.

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Author: search.filters.author.Won, Junyeon

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    Cardiorespiratory Fitness as a Moderator of Sleep-Related Associations with Hippocampal Volume and Cognition
    (MDPI, 2022-10-07) Alfini, Alfonso J.; Won, Junyeon; Weiss, Lauren R.; Nyhuis, Casandra C.; Zipunnikov, Vadim; Spira, Adam P.; Liu-Ambrose, Teresa; Shackman, Alexander J.; Smith, J. Carson
    The objective of this study was to understand the associations of sleep and cardiorespiratory fitness with hippocampal volume and global cognition among older adults (n = 30, age = 65.8 years, female = 73.3%). Wrist actigraphy provided objective measures of nighttime sleep including sleep duration, average wake bout length (WBL; sleep disturbance), and wake-to-sleep transition probability (WTSP; sleep consolidation). Cardiorespiratory fitness was quantified via cycle exercise using a modified heart rate recovery approach. Magnetic resonance imaging was used to determine hippocampal volume and the Mini-Mental State Examination was used to assess global cognition. Fitness moderated associations of sleep with hippocampal volume and cognitive performance, whereby the association of WBL—an index of poor sleep—with hippocampal atrophy was stronger among less-fit individuals, and the association of sleep duration with cognitive performance was stronger among more-fit individuals. Across the fitness levels, a longer WBL was associated with lower cognitive performance, and a higher WTSP—an index of more consolidated sleep—was associated with greater hippocampal volume. Sleep and fitness were unrelated to the volume of an amygdala control region, suggesting a degree of neuroanatomical specificity. In conclusion, higher cardiorespiratory fitness may attenuate sleep disturbance-related hippocampal atrophy and magnify the cognitive benefits of good sleep. Prospective studies are needed to confirm these findings.
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    Emotional processing and positive affect after acute exercise in healthy older adults
    (Wiley, 2023-06-12) Kommula, Yash; Purcell, Jeremy J.; Callow, Daniel D.; Won, Junyeon; Pena, Gabriel S.; Smith, J. Carson
    The well-elucidated improvement of mood immediately after exercise in older adults presumably involves adaptations in emotion-processing brain networks. However, little is known about effects of acute exercise on appetitive and aversive emotion-related network recruitment in older adults. The purpose of this study was to determine the effect of acute exercise, compared to a seated rest control condition, on pleasant and unpleasant emotion-related regional activation in healthy older adults. Functional MRI data were acquired from 32 active older adults during blocked presentations of pleasant, neutral and unpleasant images from the International Affective Pictures System. fMRI data were collected after participants completed 30 min of moderate to vigorous intensity cycling or seated rest, performed in a counterbalanced order across separate days in a within-subject design. The findings suggest three ways that emotional processing in the brain may be different immediately after exercise (relative to immediately after rest): First, reduced demands on emotional regulation during pleasant emotional processing as indicated by lower precuneus activation for pleasant stimuli; second, reduced processing of negative emotional stimuli in visual association areas as indicated by lower activation for unpleasant stimuli in the bilateral fusiform and ITG; third, an increased recruitment in activation associated with regulating/inhibiting unpleasant emotional processing in the bilateral medial superior frontal gyrus (dorsomedial prefrontal cortex), angular gyri, supramarginal gyri, left cerebellar crus I/II and a portion of right dorsolateral prefrontal cortex. Overall, these findings support that acute exercise in active older adults alters activation in key emotional processing and regulating brain regions.
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    CARDIORESPIRATORY FITNESS AND BASAL FOREBRAIN CHOLINERGIC NETWORKS IN OLDER ADULTS
    (2021) Won, Junyeon; Smith, J. Carson; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    BACKGROUND: Age-related cholinergic dysfunction within the basal forebrain (BF) is associated with cognitive decline and Alzheimer’s disease (AD) in older adults. Accumulating evidence suggests that higher cardiorespiratory fitness (CRF) is linked to neuroprotective effects. However, we have yet to understand the associations between CRF, BF cholinergic function, and cognitive function in older adults. In humans, resting state functional connectivity (rsFC) using functional MRI (fMRI) is useful to characterize the functional aspect of the BF cholinergic connectivity. PURPOSE: 1) To investigate the relationships between CRF-BF rsFC, CRF-cognitive performance, and BF rsFC-cognitive performance in older adults; 2) To investigate the moderating effects of CRF in the relationship between BF rsFC and cognitive function; 3) To investigate the possibility of BF rsFC as a neurophysiological mechanism underpinning the association between CRF and cognitive function in older adults. METHODS: We utilized a publicly available dataset from the Nathan Kline Institute Rockland Sample in which CRF, cognitive test scores (e.g., Rey Auditory Verbal Learning Test, Delis-Kaplan color-word Interference test, and D Delis-Kaplan trail making test), and fMRI data are available in a large sample of older adults. Resting-state fMRI were preprocessed using a rigorous method and valid image processing software. Linear regression models were used to assess the associations between CRF, BF rsFC, and cognitive performance in Specific Aim 1. Sex-dependent differences in the BF rsFC were also investigated as a post-hoc analysis. The interaction between CRF and BF rsFC on cognitive performance was tested using linear regression and analysis of covariance (ANCOVA) for Specific Aim 2. Mediation analysis was administered to examine the possible mediating role of BF rsFC in the relationship between CRF and cognitive function (Specific Aim 3). RESULTS: There was an association between higher CRF and greater NBM rsFC in older adults. There were significant correlations between CRF, CRF-related NBM rsFC, and trail making test performance only in women. Importantly, higher CRF was associated with better Trail Making performance through greater NBM rsFC in females. Lastly, higher CRF was associated with a greater positive association between NBM rsFC and Color-Word Interference performance in older women. CONCLUSION: Higher CRF is associated with greater NBM rsFC in older adults. The association between higher CRF and better executive function performance, however, was evident only in females. Our results further provide evidence that the NBM rsFC may be an underlying neural mechanism in the relationship between CRF and executive function specifically in older women. Hence, sex differences may exist within the CRF-related neuroprotective effects on the NBM functional network and executive function.
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    The Impact of Acute Aerobic Exercise on Semantic Memory Activation in Healthy Older Adults
    (2018) Won, Junyeon; Smith, Jerome C; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Background: A growing body of exercise literature use functional magnetic resonance imaging (fMRI) technique to measure the effects of exercise on the brain. Findings suggest that regular participation of long-term exercise is associated with enhanced cognitive function. However, fundamental questions regarding the beneficial effects of acute exercise on semantic memory have been ignored. Purpose: This study investigated the effects of a single session of exercise on brain activation during recognition of Famous names and Non-Famous names compared to seated-rest in healthy older adults (age 65-85) using fMRI. We also aimed to measure whether there are differences in brain activation during retrieval of Famous names from three distinct time epochs (Remote, Enduring, and Recent) following acute exercise. Methods: Using a within-subjects counterbalanced design, 30 participants (ages 55-85) will undergo two experimental visits on separate days. During each visit, participants will engage in 30-minutes of rest or stationary cycling exercise immediately followed by the famous name discrimination task (FNT). Neuroimaging and behavioral data will be processed using AFNI (version 17.1.06) and SPSS (version 23), respectively. Results: HR and RPE were significantly higher during exercise. Acute exercise was associated with significantly greater semantic memory activation (Famous > Non-Famous) in five out of nine regions (p-value ranged 0.027 to 0.046). In an exploratory epoch analysis, five out of 14 brain regions activated ruing the semantic memory task showed significantly greater activation intensity following the exercise intervention (Enduringly Famous > Non-Famous). Conclusions: Enhanced semantic memory processing is observed following acute exercise, characterized by greater fMRI response to Famous than Non-Famous names. Enduringly Famous names exhibited significantly greater activation after exercise compared to Non-Famous names. These findings suggest that exercise may improve semantic memory retrieval in healthy older adults, and may lead to enhancement of cognitive function.