Date of Award

Winter 2008

Document Type


Degree Name

Doctor of Philosophy (PhD)



Committee Director

Carryl L. Baldwin

Committee Director

Elaine M. Justice

Committee Member

James P. Bliss

Committee Member

David P. Swain


As our population ages, determining exogenous factors that may offset cognitive decline become increasingly important. The primary goal of the present study was to determine whether older individuals who engage in regular physical activity demonstrate superior working memory performance relative to older sedentary individuals. Forty young (20 active, 20 sedentary) and forty older (20 active, 20 sedentary) individuals engaged in cognitive measures of information processing speed, inhibitory function, and verbal and visuospatial working memory. Age differences in recall were found for verbal and visuospatial span tasks, as well as for recall reaction time on verbal and visuospatial n-back tasks, and age-related performance decrements were exacerbated in the most difficult task conditions. All participants performed less accurately and took longer to respond to stimuli as the verbal and visuospatial n-back tasks became more difficult. A second objective was to examine the effects of age and physical activity on frontal midline theta and hemispheric alpha, as a function of verbal and visuospatial n-back task difficulty. Frontal midline theta recorded at Fz increased for all participants as taskload increased for the verbal, but not visuospatial n-back task. However, as the visuospatial task became more difficult, the younger group showed a greater increase in frontal midline theta than the older group. Neither age, physical activity, nor taskload had an effect on frontal and parietal alpha asymmetry as analyzed from recordings at F3, F4, P3, and P4. The third objective was to evaluate the degree to which physical activity was related to information processing speed and inhibitory function in older adults, as these two constructs are associated with working memory. Cognitive processing speed, attention accuracy, and attention reaction time were all influenced by age. The hypothesized interaction between age and physical activity was not observed for any of the behavioral nor physiological measurements. Several possible explanations for why the main predictions were not supported are discussed, including the idea that it may be physical fitness, rather than physical activity, which contributes to healthy adult brain aging.


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