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Protracted development of brain systems underlying working memory in adolescence: a longitudinal study

Simmonds, Daniel and Luna, Beatriz (2015) Protracted development of brain systems underlying working memory in adolescence: a longitudinal study. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Working memory (WM), the ability to hold information on line to guide planned behavior, continues to improve through adolescence in parallel with brain maturational processes of systems known to support it. Initial studies have only examined individuals once or twice, limiting our understanding of developmental trajectories, leading to sparse and conflicting results. Further, it is unclear how age-related changes in WM performance and neural processes are associated, and what mechanisms might underlie these changes. In this study, we report on developmental improvements of WM performance and changes in brain function and connectivity of systems underlying WM using functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), in a large longitudinal sample in which participants were followed annually for up to nine years. First, results confirmed that WM performance continues to improve into the early 20's. Alongside these refinements, brain activity in the frontal eye fields (FEF) and parietal cortex continue to change during this time; age-related changes in prefrontal regions were specifically associated with WM performance, suggesting a primary role in WM improvements. Supporting these changes, task-related functional connectivity from dorsolateral prefrontal cortex (DLPFC) to FEF, visual association cortex (VAC), and cingulate regions continued to change during adolescence and were related to WM development. Greater connectivity was associated with less mature behavior, suggesting a decreased reliance on top-down communication to support WM with development. DTI results indicated robust increases in white matter integrity across the brain with the several tracts connecting prefrontal and posterior systems, continuing to mature into early adulthood. Further, white matter measures were correlated with behavior, functional activity, and functional connectivity, suggesting that the development of structural connections may provide a scaffold on which cognitive and functional brain development can specialize. Taken together, these results suggest that while regional prefrontal function supports the transition from childhood to adolescence, the period of transition to adult level WM performance is characterized, by enhancements in prefrontal functional and structural connectivity to posterior regions supporting mnemonic aspects of working memory residing in attention and visual association regions.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Simmonds, Danieldjs81@pitt.eduDJS81
Luna, Beatrizlunab@upmc.eduLUNA
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Thesis AdvisorLuna, Beatrizlunab@upmc.eduLUNA
Committee ChairFiez, Juliefiez@pitt.eduFIEZ
Committee MemberOlson, Carlcolson@cnbc.cmu.eduOLSONC
Committee MemberErickson, KirkKIERICKS@pitt.eduKIERICKS
Committee MemberVerstynen, Timothy D.timothyv@pitt.eduTIMOTHYV
Date: 28 April 2015
Date Type: Publication
Defense Date: 5 March 2015
Approval Date: 28 April 2015
Submission Date: 23 April 2015
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 108
Institution: University of Pittsburgh
Schools and Programs: School of Medicine > Neurobiology
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: dorsolateral prefrontal cortex, frontal eye fields, visual association cortex, cingulate, executive, sensorimotor, cognitive, maturation, timing, stages, epochs, functional magnetic resonance imaging, functional connectivity, beta series, diffusion tensor imaging, individual differences, brain-behavior, structure-function
Date Deposited: 28 Apr 2015 12:02
Last Modified: 19 Dec 2016 14:42


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