Date Approved

5-19-2020

Embargo Period

5-21-2020

Document Type

Dissertation

Degree Name

PhD Doctor of Philosophy

Department

Psychology

College

College of Science & Mathematics

First Advisor

Libon, David J.

Second Advisor

Nagele, Robert

Third Advisor

Baliga, Ganesh

Subject(s)

Memory; Mild cognitive impairment

Disciplines

Cognition and Perception | Psychology

Abstract

Background: Fuster (2008) observed that temporal organization modulate executive control mechanisms by generating (1) attention towards test parameters (working memory), (2) the capacity to execute a task (preparatory set), and (3) the ability to inhibit external/internal stimuli (inhibitory control). We investigated Fuster's model (2008) using response latency on visual and verbal working memory tasks in patients with suspected mild cognitive impairment (MCI). Methods: An iPad-version of the Backward Digit Span Test (BDT) and Symbolic Working Memory Test (SWM) were used. Outcome variables were latency for each correct serial position and volumetric subcortical regions using NeuroQuant® software. Results: Mixed-model analyses found within-group differences on both BDT and SWM. Moreover, group by latency interaction for each position as a function of total time was observed on the BDT. Correlations between total time for correct trials and neuropsychological measures of processing speed and visuospatial operations were significant for the BDT. Finally, MRI was not associated with any serial order position. Conclusions: Consistent with Fuster's model, BDT latencies illustrate a tripartite neurocognitive construct. The allocation of latency for correct trials differed between the MCI and non-MCI groups to suggest distinct underlying neurocognitive constructs. Together, latency on verbal WM tasks like the BDT may be a cognitive marker for emergent illness.

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