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The role of GABA in fear and its relationship to emotion processing brain networks

Lipp, Ilona 2014. The role of GABA in fear and its relationship to emotion processing brain networks. PhD Thesis, Cardiff University.
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The aim of the project described in this thesis was to explore the relationship between the inhibitiory neurotransmitter gamma-aminobutyric acid (GABA) and fear-related brain activation, measured with functional magnetic resonance imaging. The first part of the thesis deals with the question of how repeatable measures of fearrelated brain activation can be obtained. Two paradigms were evaluated, a frequently used task using fearful and neutral faces and a newly developed paradigm using pictures of spiders, negative images from the international affective picture system, and carefully matched control stimuli. In the main study latter paradigm was used to assess fear-related BOLD responses in two groups of participants, recruited for high vs. low levels of fearfulness. In the same participants, GABA concentration was measured using MRS in two brain regions relevant for emotion processing (left insula and left dorsolateral prefrontal cortex). Additionally, physiological parameters were recorded throughout the task, and a breath-hold task (to estimate vascular reactivity) as well as an arterial spin labeling aquisition (to estimate baseline cerebral blood ow) were included in the scanning session. The main experimental chapters of the thesis deal with the questions whether fearfulness,GABA concentration and fear-related BOLD responses are associated, and how potential confounding factors - such as physiological task responses, vascular reactivity and baseline cerebral blood ow - might mediate this relationship. The last part of the main experimental part explores the relationship between fearfulness, GABA concentration and resting state functional connectivity in emotion processing networks. In the general discussion, power of the study is estimated post-hoc, and limitations are outlined. Two chapters in the Appendix assess repeatability of the GABA MRS measures and vascular reactivity estimates.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Psychology
MRC Centre for Neuropsychiatric Genetics and Genomics (CNGG)
Subjects: B Philosophy. Psychology. Religion > BF Psychology
Funders: President's Research Scholarships
Date of First Compliant Deposit: 30 March 2016
Last Modified: 04 Jun 2017 07:48

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