Genetics of functional brain networks

Sinclair, Benjamin (2015). Genetics of functional brain networks PhD Thesis, School of Psychology, The University of Queensland. doi:10.14264/uql.2015.884

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Author Sinclair, Benjamin
Thesis Title Genetics of functional brain networks
School, Centre or Institute School of Psychology
Institution The University of Queensland
DOI 10.14264/uql.2015.884
Publication date 2015-08-31
Thesis type PhD Thesis
Supervisor Katie McMahon
Margie Wright
Greig de Zubicaray
Total pages 154
Language eng
Subjects 1702 Cognitive Sciences
1109 Neurosciences
0604 Genetics
Formatted abstract
In this thesis, the heritability of a number of features of brain functional connectivity and network behaviour was estimated, in order to assess their suitability as imaging endophenotypes. Phenotypes were chosen based on prior association with psychiatric disease in the literature, and current interest in the neuroimaging community. Heritability was estimated using a large MRI twin sample from the Queensland Twin Imaging Study.

The first study looks at intrinsic functional brain networks present at rest, in the absence of cognitive demand, and characterised them using graph theory, a mathematical formulation used to describe topological properties of complex networks. Such characteristics were found to be moderately to strongly heritable (h2=20-60%). The heritability estimates varied substantially with methodological choices, in particular the removal or inclusion of global signal.

Connectivity of functional brain networks during working memory performance were also examined. Dynamic causal modelling was employed to determine task-related changes in functional coupling between frontal and parietal regions. Changes in connectivity with task demand were observed for both forward and backwards connections, but the changes had low test-retest reliability (ICC≤0.3), and subsequently, twin correlations and heritability were non-significant (rMZ≤0.08, rDZ≤-0.05).

Finally the functional connectivity profile of the dorsolateral prefrontal cortex during working memory was probed. Functional connectivity with ipsilateral parietal cortex (h2=24%), contra-lateral dorsolateral prefrontal cortex (h2=36%), posterior cingulate cortex (h2=37%) and middle frontal cortex (h2=26%) were found to be heritable. However, the connections during baseline condition were also heritable, suggesting the heritability did not pertain to WM-specific connectivity, and connectivity with left hippocampus was not found to be heritable.
Keyword Neuroscience
Resting state fMRI
Working memory
Functional connectivity
Graph theory
Dynamic causal modelling (DCM)

Document type: Thesis
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Created: Thu, 27 Aug 2015, 11:38:49 EST by Mr Benjamin Sinclair on behalf of Scholarly Communication and Digitisation Service