Melbourne School of Psychological Sciences - Theses
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ItemVolumetric Analysis of the Entorhinal and Transentorhinal Cortices in the Early Detection of Alzheimer’s Disease( 2024-02)Diagnosing Alzheimer’s disease (AD) early in the disease process can be challenging. Incorporating biomarkers into the diagnostic evaluation for AD has been recommended to increase diagnostic accuracy. Structural magnetic resonance imaging (MRI) is a particularly appealing biomarker because it is a widely available and noninvasive procedure. In view of the early pathological involvement of the entorhinal and transentorhinal cortices in the disease process, MRI-based volume measurements of these regions are promising candidate markers for early AD. Whilst significant advances have been achieved in automated segmentation of brain MRI in recent years, the entorhinal and transentorhinal cortices have been shown to be particularly challenging regions for automated segmentation. The current dissertation sought to examine the role of entorhinal and transentorhinal cortical MRI volumetric analysis to enhance the early detection of AD. Chapter 2 presented a systematic review and meta-analysis of studies comparing automated and manual regional brain volume measurements across healthy controls (HCs), individuals with amnestic mild cognitive impairment (aMCI), and individuals with AD dementia. There was no significant difference in automatic and manual volume measurements for the hippocampus, lateral ventricles, and parahippocampal gyrus. There was, however, significant heterogeneity in the effect estimates across the studies. Chapter 3 comprised an investigation into the effect of MRI scan orientation on the reliability of entorhinal and transentorhinal cortical volume measurement in order to establish a standard protocol for segmentation for subsequent Chapters. Aligning MRI scans to a common orientation improved the reliability of entorhinal and transentorhinal cortical volume measurement. Chapter 4 described an independent validation of a recently developed automated segmentation method, Automatic Segmentation of Hippocampal Subfields-T1 (ASHS-T1), for the measurement of entorhinal and transentorhinal cortical volumes in HCs, individuals with aMCI, and individuals with AD dementia. Despite differences between the volumes obtained from ASHS-T1 and those obtained from manual segmentation, ASHS-T1 was sensitive to AD-related entorhinal and transentorhinal cortical atrophy. Chapter 5 contained an examination of the contribution of selected mesial temporal lobe volumes obtained from ASHS-T1 alongside test scores derived from comprehensive neuropsychological assessment to aid identification of individuals with aMCI and individuals with AD dementia in a memory clinic cohort. Volumes of the entorhinal cortex, transentorhinal cortex, and hippocampus performed no better than chance and offered no utility over and above valid and reliable neuropsychological measures for identifying individuals with AD. Chapter 6 introduced a novel, deep learning-based automated segmentation method, TransEntorhinal Segmentation by Deep Learning (TES-DL), to segment the entorhinal and transentorhinal cortices. Despite suboptimal segmentation accuracy, TES-DL showed mostly medium to large effect sizes for the differences in entorhinal and transentorhinal cortical volumes between HC, aMCI, and AD groups in two AD cohorts. Taken together, the findings from the current dissertation highlight the difficulty of accurate automated segmentation of the entorhinal and transentorhinal cortices and challenge the clinical utility of the volumes of these regions in the early detection of AD. Importantly, whilst advances in automated neuroimaging methods promise exciting new possibilities, it is essential that these methods are thoroughly validated prior to widespread clinical application.
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ItemUnderstanding the Mental Health Impacts and Support Needs Following Coercive Control( 2024-01)Coercive control is a complex, insidious and under-researched dimension of psychological intimate partner violence (IPV) that has been associated with trauma and mental health impacts. This thesis had two overarching aims: (1) to improve the understanding of the trauma and mental health impacts of coercive control, and (2) to explore the mental health support needs and wants of women following coercive control exposure to aid their long-term recovery. To achieve these aims this thesis employed a mixed methods approach and included three separate yet interlinked studies: a systematic review and meta-analysis, and two qualitative reports. The review aimed to examine quantitative associations involving coercive control with posttraumatic stress disorder (PTSD), depression and complex PTSD (CPTSD) and included 68 observational studies. Data from 45 studies were included in the meta-analyses. Meta-analyses showed that coercive control exposure was moderately associated with both PTSD and depression. The associations were comparable to those between broader dimensions of psychological IPV and PTSD and depression that were also investigated in the review, and with associations involving physical IPV with PTSD and with depression examined in previous meta-analyses. Only one study reported on the relationship between coercive control and CPTSD and meta-analyses could not be performed. Studies 2 and 3 addressed gaps that were identified in the systematic review and meta-analysis. To enhance the understanding of the trauma and mental health impacts of coercive control and the support needs of victim-survivors, a qualitative approach was employed for studies 2 and 3, and 16 women who had experienced coercive control were interviewed. Study 2 reported on these women’s lived experience of the mental health impacts of coercive control. Study 3 explored what types of psychological supports women need and want to aid their long-term recovery. Building on the findings of study 1, studies 2 and 3 made six key contributions to the coercive control literature: (1) Clarification of the coercive control construct by identifying entrapment (including social entrapment) and insidiousness (characterised by subtlety, intangibleness, gradual worsening), as the underlying dimensions of coercive control that likely differentiate coercive control from other dimensions of IPV, and may be associated with unique mental health reactions; (2) evidence that coercive control exposure should be recognised as a traumatic event; (3) qualitative evidence for the association between coercive control and CPTSD symptoms; (4) proposition that the ongoing threat and terror, insidiousness and entrapment of coercive control contribute to the unique and complex trauma and mental health reactions that may be reflected in CPTSD symptoms; (5) the need for a holistic recovery focus that integrates clinical and personal recovery; and (6) the need for integrated trauma-and-coercive control-informed psychosocial interventions. Taken together, this thesis has made several significant contributions to the coercive control literature that have important implications for policy, clinical practice and research.
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ItemTowards a functional action-based account of Moralization( 2023-12)Morality has traditionally been considered to reflect a set of universal and objective values. However, more recent work investigating people’s subjective moral beliefs have revealed that substantial and meaningful variance can exist within and between individuals in their tendency to see attitudes or actions as morally relevant. Moralization describes the process underlying within-person variance in attribution of moral significance to actions or attitudes. In this thesis we build on recent work investigating the mechanisms of subjective moralization by proposing the action-based moralization account – a framework that conceptualises moralization as functional response to action-based uncertainty in the context of threat-appraisal. To evaluate the utility of this account as a functional theory of moralization, we apply a multi-method approach to investigate the relationship between threat-appraisal and moralization. Specifically, we find evidence of a relationship between individual differences in threat-sensitivity and tendency for moralization. Through an ecological momentary assessment study, we also find that within-person variation in the experience threat-appraisal related affect predicts moralization. Finally, in two representative sample studies in the U.S. and U.K we find that individual differences in subjective threat-appraisal of COVID-19 is positively associated with moralization of COVID-19 preventative behaviours. Finally, we investigate the longitudinal relationship between moralization and uncertainty reduction in the context of a real-world political event. We find that moralization is associated with prediction confidence at time 1, and predicts subjective belief confirmation at time 2. Collectively, these findings provide initial support for the action-based moralization account, and highlight the value of functional theories as a framework for understanding the precursors and outcomes of moralization.
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ItemAn investigation of the holistic processing of faces( 2023-11)Whether it is due to the specific configuration of faces or our particular expertise with them, faces are seen to be a special class of object and, hence, processed differently compared to most other stimuli in our environment. One influential concept - holistic processing - has been used to describe how we process faces. In general, the concept of holistic processing is based on the idea that the entire face object is perceived and processed as a single unit instead of as individual parts or an aggregate of those parts. However, there is no single clear operationalisation of holistic processing in the literature, and the various experimental paradigms used seem to assess different aspects of processing. In this thesis, I explore the different ways holistic processing has been investigated and provide an in-depth examination of the underlying processing of composite faces. According to theories of information processing, holistic processing can be operationalised as a coactive architecture where all face information is combined into a single channel, which then drives decision-making in specific tasks. Coactive processing can be distinguished from other processing architectures such as serial and parallel processing using systems factorial technology and model-fitting. Overall, our composite faces were best fit by a mixture of serial and parallel processing, indicating little support for the argument that faces are processed holistically. We further investigate this mixture model and discuss how these results can be situated on a continuum which ranges from analytic, independent processing to complete, holistic processing.
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ItemModelling the impact and organisational factors on work(University of Melbourne, 2009)
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ItemThe psychosocial effects of a newly-diagnosed seizure in adulthood(University of Melbourne, 2009)
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ItemThe neurological correlates of the k-complex(University of Melbourne, 2009)
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ItemSpatial learning and memory in a virtual environment : temporal lobe damage and neurotransmitter correlates(University of Melbourne, 2008)
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