Date of Award

May 2017

Degree Type

Thesis

Degree Name

Master of Science

Department

Psychology

First Advisor

David C. Osmon

Committee Members

Christine Larson, Bonita Klein-Tasman

Keywords

Attention Control, Healthy Aging, White Matter Integrity

Abstract

The influence of structural brain changes in healthy aging on cross-modal selective attention performance was investigated with structural MRI (T1- and diffusion-weighted scans). Eighteen younger (M=26.1, SD=5.7) and 18 older (M=62.4, SD=4.9) healthy adults with normal hearing performed a reaction time (RT) cross-modal selective attention A/B/X task. Participants discriminated syllables presented in either visual or auditory modalities, with either randomized or fixed distraction presented simultaneously in the opposite modality. Within the older group only, RT was significantly slower during random (M=573.24, SE=33.66) compared to fixed (M=554.04, SE=33.53) distraction, F(1,34)=5.41, p=.026. Average gray matter thickness and white matter integrity were lower for older adults, all p<.05. Across the age range, lower average gray matter thickness in regions of the ventral (VAN), but not dorsal (DAN), attention network correlated with larger increases in RT related to distraction, all p<.05. Multiple regression revealed that white matter integrity did not predict RT distraction index (random-fixed), all p>.05. However, post-hoc adaptive lasso regressions demonstrated that FA of bilateral SLF predicted RT distraction index, Wald 2=3.88, p=.016. The present results indicate that structural integrity underlying both DAN and VAN may aid in cross-modal selective attention performance, suggesting that communication between the networks, likely via top-down modulation of bottom-up processes, may be crucial for optimal attention regulation.

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