29.3086, Diss: Neurolinguistics: Riley Chase Pearsall: ''The Relationship Between Lexical Performance and Regional Gray Matter Volumes: A Longitudinal Study of Cognitively Healthy Elderly ''

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LINGUIST List: Vol-29-3086. Fri Aug 03 2018. ISSN: 1069 - 4875.

Subject: 29.3086, Diss: Neurolinguistics: Riley Chase Pearsall: ''The Relationship Between Lexical Performance and Regional Gray Matter Volumes: A Longitudinal Study of Cognitively Healthy Elderly ''

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Date: Fri, 03 Aug 2018 11:44:54
From: Jungmoon Hyun []
Subject: The Relationship Between Lexical Performance and Regional Gray Matter Volumes: A Longitudinal Study of Cognitively Healthy Elderly

 Institution: CUNY Graduate Center 
Program: Linguistics 
Dissertation Status: Completed 
Degree Date: 2016 

Author: Riley Chase Pearsall

Dissertation Title: The Relationship Between Lexical Performance and Regional
Gray Matter Volumes: A Longitudinal Study of Cognitively
Healthy Elderly 

Linguistic Field(s): Neurolinguistics


Dissertation Director(s):
Loraine Obler

Dissertation Abstract:

This study investigated the longitudinal relationship among aging, performance
on lexical tasks, and regional gray matter volumes over 2-7 years. A total of
137 older participants who remained cognitively normal were administered four
lexical tasks at each time point: the Boston Naming Test (BNT), Vocabulary
Test, Semantic- and Phonemic-Fluency task. In addition, they underwent
repeated magnetic resonance imaging (MRI) scanning acquired within two months
of the lexical tasks. The average interval between time points was 2.36 years
(range 1.50-7.64) and the average number of time points was 2.65 times (range
2-5).

Results indicated that age differentially affects lexical task performance in
two ways. First, baseline age was significantly negatively related to the
scores on the BNT and Semantic Fluency task but not related to the Vocabulary
test and Phonemic Fluency task. Second, the interval between the baseline and
follow-ups was significantly related to the performance on the BNT, Vocabulary
test and Semantic Fluency task. The longer the interval between the
observations, the lower the scores on these tasks. This shows that as people
get older, general lexical production ability within participants declines.
Moreover, the rate of change in performance over time varies across tasks.
Older participants tended to score lower at each successive time point and the
rate of decline was greater on the tasks that impose more constraints on
semantic and phonemic specificity than the tasks that demand less specificity
in lexical selection. Thus, the BNT and Semantic Fluency tasks are more
sensitive to age-related lexical performance changes in cognitively normal
older adults than are Phonemic Fluency tasks or Vocabulary Test. Further, the
interval effect clearly shows that as time progresses older adults’ lexical
production abilities decline on all tasks except in the Phonemic Fluency.

Regarding the relationship between regional brain volumes and lexical
performance over time, common and specific association patterns were found.
Individual brain regions whose volume reduction predicted lexical performance
decline were found in the bilateral temporal, parietal and frontal cortices.
More specifically, the volumes of the medial temporal lobes (MTL) were
significantly related to performance on all four lexical task, while other
brain regions showed distinctive association patterns with individual tasks;
the frontal pole was related to accuracy on the BNT; the temporal pole,
supramarginal gyrus, superior frontal and superior parietal cortices to the
scores on the Vocabulary Test; the dorsolateral prefrontal and precuneus to
the scores on the Semantic Fluency task; the fusiform gyrus, inferior frontal,
superior parietal, superior and inferior temporal cortices to the scores on
the Phonemic Fluency task. When these significant regions were jointly
analyzed, significant task-related clusters emerged for the BNT and Vocabulary
test. For the BNT performance, the bilateral MTL and left frontal pole were
crucial; for the Vocabulary test, while the left superior temporal cortex and
bilateral MTL were important.



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