Access Type

Open Access Dissertation

Date of Award

January 2016

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Psychology

First Advisor

John L. Woodard

Abstract

Introduction: Several functional magnetic resonance imaging (fMRI) studies have analyzed the famous name discrimination task (FNDT), an uncontrolled semantic memory probe requiring discrimination between famous and unfamiliar individuals. Completion of this simple task recruits a semantic memory network that has shown utility in determining risk for Alzheimer's disease (AD). Specific semantic memory probes using biographical information associated with famous individuals may build on previous findings and yield superior information regarding risk for AD.

Method: Sixteen cognitively intact elders completed the FNDT and two novel tasks during fMRI: Categories (matching famous individuals to occupational categories) and Attributes (matching famous individuals to specific bodies of work or life events). Five participants were carriers of the Apolipoprotein E (APOE) ε4 allele.

Results: Relative to their respective control tasks, participants recruited brain regions for all three tasks consistent with previous research, including left temporal lobe, left angular gyrus, precuneus, posterior cingulate, and anterior cingulate. The FNDT generated significantly more activity than the other tasks in anterior cingulate and several posterior regions. Categories had significantly lesser activity than other tasks in inferior parietal lobe, precuneus, and posterior cingulate. Attributes, the most specific semantic probe, demonstrated the strongest left lateralization with significantly greater activity in left inferior frontal gyrus and anterior temporal lobe. APOE ε4 carriers had regions with greater activity across all three tasks, with the greatest number of regions for Attributes, including in left anterior temporal lobe.

Discussion: This pilot study identified neural correlates of different levels of semantic processing. The FNDT, an unconstrained semantic knowledge probe, demonstrated greater activity across most regions. The Attributes task, a specific semantic probe, had focused left-lateralized activity, including anterior temporal lobe and inferior frontal gyrus. APOE ε4 carriers demonstrated significantly greater activity in left anterior temporal lobe during Attributes only, demonstrating this task's potential utility for determination of AD risk.

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