Aghjayan, Sarah
(2020)
ASSOCIATIONS BETWEEN CARDIORESPIRATORY FITNESS AND WORKING MEMORY FMRI BRAIN ACTIVITY.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Working memory (WM) and associated brain areas show deficits with increasing age. However, higher cardiorespiratory fitness (CRF) has been associated with better WM across the lifespan. The mechanisms by which CRF impacts WM are poorly understood. One possible mechanism is that CRF influences the integrity and function of brain regions that are involved in supporting WM function, and that this, in turn, influences accuracy rates on tasks that measure WM. Very few studies have tested whether the association between CRF and WM is statistically mediated by measures of brain function. This study addressed this gap in knowledge by examining the relationship between CRF, brain activation, and WM. We tested whether brain activation during a WM task statistically mediated the relationship between CRF and WM.
Baseline data of 125 adults (M=44.34 ± 8.60 years) were included in this study. CRF was assessed via a submaximal graded exercise test. Magnetic resonance images were collected during the n-back task to examine neural responses to WM. FMRIB’s Software Library was used for fMRI data preprocessing and analysis. Regions-of-interest were defined by conducting a conjunction analysis to identify brain regions sensitive to both CRF and performance on the n-back task. Linear regression models examined the association of CRF with WM and brain activation in the left anterior cingulate cortex, left insula, and right insula.
After controlling for age, gender, race, and years of education, CRF was not significantly related to accuracy on the WM task (all p>.15). However, consistent with our hypotheses, higher CRF was significantly related to greater brain activation in the left insula (p<.028) during the 2-back WM condition. Heightened brain activation in the left insula was not associated with WM accuracy (p=.12) after correction for variation due to age, gender, race, and education. Thus, statistical mediation could not be tested.
Although higher CRF was associated with greater brain activation in the left insula, neither CRF nor heightened left insula activation were associated with variations in WM performance after adjusting for several confounding variables. These results suggest that there are other mediators that explain the relationship between CRF and WM performance in midlife.
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| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
8 June 2020 |
| Date Type: |
Publication |
| Defense Date: |
16 September 2019 |
| Approval Date: |
8 June 2020 |
| Submission Date: |
15 October 2019 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
46 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Psychology |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
midlife |
| Date Deposited: |
08 Jun 2020 14:58 |
| Last Modified: |
08 Jun 2020 14:58 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/37712 |
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