Browsing by Author "Campbell, Kathryn"

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    The Bewildered Brain: Asymmetric Brain Activity as a Source of Cognitive Impairment in Depression
    (Massey University, 2011) Campbell, Kathryn; Hill, Stephen; Podd, John
    Individuals with depression commonly complain about cognitive deficits such as memory loss and poor decision making ability (Lahr, Beblo, & Hartje, 2007). However, despite considerable research, no single profile of cognitive deficits in depression has emerged (Ravnkilde et al., 2002). This may be a result of heterogeneity within the diagnostic category of depression. While typically diagnosed as a single disorder, the symptoms of depression may stem from different neurobiological causes leading to different profiles of cognitive deficits. Shenal, Harrison, and Demaree (2003) theorised that subtypes of depression could arise from dysfunctional brain activity in each of the quadrants of the brain (right frontal, left frontal, right posterior, and left posterior). For example, reduced left frontal activity in depression may be associated with impairments in tasks reliant on left frontal regions. Little research has directly investigated the possible link between variability in cognitive deficits and different patterns of dysfunctional brain activity in depression. The current paper reviews evidence for this link by describing depressed individuals’ performance on lateralised cognitive tasks, and discusses possibilities for future research.
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    The blue brain : hemispheric asymmetry in depression as an explanation for working memory impairment : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Psychology at Massey University, Manawatu, New Zealand
    (Massey University, 2015) Campbell, Kathryn
    Due to substantial variability in past research regarding the cognitive and neurobiological correlates of depression, the current study investigated whether taking the possible relationship between asymmetric brain activity and cognitive impairment into account would help to clarify the matter. A total of 78 participants including 36 currently depressed, 11 previously depressed, and 31 never depressed participants, completed three mood questionnaires (Beck Depression Inventory, Hamilton Depression Inventory Short-Form, and the State-Trait Anxiety Inventory), and four working memory tasks (a spatial and verbal variant of both the N-back and complex span task). All participants had their resting brain activity recorded using an electroencephalogram. It was hypothesised that depressed participants would show relatively reduced left frontal activity, since left frontal activity is linked to positive affect and approach motivation, and that participants with depression but low levels of anxiety would show reduced right parietal activity while those with high anxiety would show increased right parietal activity due to the role of the right parietal area in arousal. These hypotheses were not supported as there were no differences in asymmetry scores between the currently depressed and the never depressed groups. However, investigation of this hypothesis was hindered by the high comorbidity of anxiety and depression making it impossible to disentangle the effects of depression and anxiety on parietal activity. It was also hypothesised that participants with depression would show impaired working memory with disproportionate impairment in the verbal working memory tasks that are thought to utilise left frontal brain activity. There was no clear support for this hypothesis. In fact, there was a trend toward improved performance possibly related to increased attention to detail due to activation of stress systems signalling a potential threat in the environment. A final hypothesis was that there would be an association between different patterns of brain activity and WM impairment but no association was found. These results highlight problems with research in this field including the conceptualisation and measurement of depression and cognitive performance as well as problems distinguishing between anxiety and depression. Future research needs to address these issues.
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    Into the Void: The Gap Between N-Back and Complex Span Tasks Suggests Inadequacies in Current Models of Working Memory
    (School of Psychology, Massey University, 2012) Campbell, Kathryn; HIll, Stephen; Podd, John
    The tasks used to assess working memory are a highly contentious issue in cognitive psychology. Previous research has found a weak relationship between two key types of working memory tasks: N-Back and Complex Span. This is commonly interpreted as evidence that one or both tasks possess poor construct validity. However, this finding may be a result of assessing different modalities of working memory. The current pilot study aimed to clarify the differences between the two tasks by assessing performance on each within the same modality. A spatial and verbal version of each task was used. Although, theoretically, these tasks assess the same construct, the pilot data revealed low correlations between them. This suggests that the current models of working memory may be inadequate, or that unidentified differences between the tasks may be influencing the results. Due to their widespread use and applications, it is important to better understand models of working memory and develop improved tasks.