Browsing by Author "Blignaut, Julianne"
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- ItemEEG investigation into the neural mechanisms involved in higher order decision-making(Stellenbosch : Stellenbosch University, 2019-04) Blignaut, Julianne; Van den Heever, David Jacobus; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering (CRSES)ENGLISH ABSTRACT: Decision-making forms a fundamental part of executive cognition. Our lives are a series of choices: some are simple, while others require more deliberation. Unravelling the neural networks that underlie the decision-making process plays an integral part in understanding to what extent these networks are informed by conscious perception and to what extent they rely on internal neural mechanisms. Our choices are the product of an interaction between our genetic makeup and subjective experiences. Failure to understand the individual’s brain has led us to a scientific impasse. We have some understanding of what happens in the brain when making arbitrary choices, but the intricacies of higher order, deliberate decision-making remain unclear. Recent studies suggest that the choices we make are deterministically formed, prior to conscious awareness of intent. This limits the role of consciousness in the decision-making process and challenges the notion of conscious free will. However, most of these studies rely on arbitrary choices devoid of real-world relevance. In 2017, Maoz et al. introduced deliberate, higher order decisions into the existing realm of studies on free will. The aim of the current research was to further investigate the neural mechanisms underlying higher order decision-making. Moreover, this research aimed to investigate the influence of traumatic subjective experiences on neurophysiological responses. The study developed an experiment that measured participants’ electro-encephalographic potentials while performing both arbitrary and deliberate choice tasks. Thereafter, the neural correlates of both decision types were evaluated and compared. Participants were presented with legal cases and had to acquit or convict one out of two criminal offenders per choice trial. The neurophysiological data was evaluated with a specific focus on the readiness potential and the P300 potential. The readiness potential has previously been used to prove the absence of free will in self-initiated action, whereas the P300 is a potential associated with the reaction to a decision. Clear readiness potentials and P300 potentials were observed for both arbitrary and deliberate decisions. Furthermore, participants who had been victims of violent crimes showed increased readiness potential amplitudes and decreased P300 potential amplitudes. Participants with close relatives who had been victims of violent crimes also showed increased readiness potentials, however, they showed increased P300 potentials too. The spatial distribution of electrical activity demonstrated greater prefrontal cortex activation for participants with close relatives who had been victims of violent crimes, compared to participants without close relatives who had been victims of violent crimes. These findings are demonstrative of how traumatic subjective experiences influence the neuro-physiology of decision-making.