Year

2018

Degree Name

Doctor of Philosophy

Department

School of Psychology

Abstract

The field of brain dynamics seeks to identify the contributions of the electroencephalographic (EEG) activity to the event-related potential (ERP) component outcomes. Research in this topic area is essential to help advance our understanding of the mechanisms underlying ERP genesis, and the identification of factors that play a significant role in their generation. However, early brain dynamics was largely plagued by empirical inconsistencies, and this, in combination with limitations in analytical and quantification techniques, resulted in a shift of focus away from this research area. In order to reignite the research in this area and provide a basis for mechanism/theory development, the present doctoral thesis aimed to identify the robust patterns of EEG-ERP amplitude and EEG-Reaction Time (RT) relationships, assessing the contributions from the immediately-prestimulus EEG brain states as indexed via the four traditional bands: delta, theta, alpha, and beta. This was undertaken via three empirical investigations. The first study was designed to map the EEG-ERP dynamics in young adults in order to resolve inconsistencies in the prior literature. The equiprobable auditory Go/NoGo task was utilised in this pursuit. The second investigation then sought to map the brain dynamics in a new young adult sample, while they completed an auditory habituation paradigm with count and ‘no task’ instructions. A comparison of the outcomes in the first and second investigations thus provided insight into the taskdependent nature of the uncovered patterns of brain dynamics. Finally, in light of the well-known agerelated changes documented in both EEG and ERP measures, the third empirical investigation set out to assess if the brain dynamics patterns identified in the initial investigations were generalisable across age. For this study, the equiprobable auditory Go/NoGo paradigm was again utilised, and gender-matched samples of young and independent-living older adults were assessed. Throughout the progression of this thesis, improvements in methodological and analytical techniques were identified and implemented. Across the three investigations, the prestimulus delta brain state was identified as having the most stable impact on the ERP component amplitude outcomes. Prestimulus delta directly (cf. inversely) modulated the positivity of the component amplitudes, and this was generally found across the range of ERP components, paradigms, and populations assessed, and was also consistent across peak-picking and principal components analysis (PCA) ERP quantification techniques. Brain dynamics in the remaining bands showed more complexity in their EEG-ERP and EEG-RT relationships. Prestimulus theta showed some specificity for the region of interest selected for its assessment, while the impact of prestimulus alpha amplitudes on the subsequent ERP component amplitudes appeared most sensitive to the ERP quantification methodology employed in their derivation. Prestimulus beta generated the most complex pattern of the four assessed bands, and it was not apparent which factor/s contributed to its impact on the ERP component amplitudes. Together, these complex patterns of results implicate each of the prestimulus EEG frequency bands as significant determinants of the ensuing ERP, and in some instances RT, outcomes. These findings indicate a way forward in decoding the mechanism/s underlying ERP genesis.

FoR codes (2008)

170101 Biological Psychology (Neuropsychology, Psychopharmacology, Physiological Psychology), 170102 Developmental Psychology and Ageing, 170110 Psychological Methodology, Design and Analysis, 170112 Sensory Processes, Perception and Performance

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.