All ETDs from UAB

Advisory Committee Chair

Kristina M Visscher

Advisory Committee Members

Lesley A Ross

Joel L Berry

Document Type

Thesis

Date of Award

2013

Degree Name by School

Master of Science in Biomedical Engineering (MSBME) School of Engineering

Abstract

Cognitive deficits that occur as a function of age are highly variable within a sample of older adults of similar age. Training paradigms are available that can reverse cognitive declines that occur with age and improve behavioral performance. However, the benefits of training are also highly variable. The goal of this study was to use func-tional connectivity analyses on functional MRI data to help identify the source of this variability and to determine if cognitive training could alter network structure in the ag-ing human brain. Resting-state functional connectivity data was acquired to investigate several neural networks in forty-one older adults. Standard functional connectivity and graph theory metrics were used to analyze the structure of networks in the brain. We found that training-related decreases in connectivity were correlated with improvement in behavioral performance on the CRT. This means that training refined network structure to ameliorate behavioral deficits. We also examined baseline connectivity differences be-tween participants who were at high-risk for cognitive decline and those who were at low-risk. Previous studies examining age-related cognitive changes found that older adults' brains were dedifferentiated and suffered from altered connection strengths rela-tive to younger adults. Therefore, we expected to see greater signs of dedifferentiation in our high-risk group. Although there were no significant differences, there were patterns in mean connectivity and mean clustering coefficient that indicated participants who were at high-risk for cognitive decline had stronger functional connectivity compared to partic-ipants who were at low-risk for cognitive decline. This would be consistent with dediffer-entiation and the results observed with training. Training may be differentiating the sys-tem by refining functional connectivity to improve behavioral performance. Further re-search needs to be done with a larger sample to better investigate differences in connec-tivity between high-risk and low-risk older adults.

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