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Abstract
Flexible allocation of attentional resources based on internal goals and context cues is essential for survival. Higher-order processes which utilize this skill, including inhibition of prepotent behavior, working memory manipulation, and task switching, are collectively termed cognitive control. Inefficiencies in these processes are often observed in the psychosis patient population, and they might contribute to the common syndrome-related decrease in daily functioning. Understanding the biological basis of cognitive control processes would benefit the medical field as much as the general population, as reversing past decline and improving cognitive function are of wide public interest. Each of the chapters 2, 3 and 4 in this dissertation described an original study which leveraged temporal resolution of neuroimaging techniques to study the brain physiology underlying cognitive control in psychosis and healthy samples. Chapter 2 modeled the tradeoff between speed and performance of antisaccade, an ocular motor act which requires inhibition, and the tradeoff rates were compared between healthy and psychosis patient groups. These distinct tradeoff rates can in the future help improve clinical identification of psychosis cases through their ocular motor control. Chapter 3 examined the P300 ERP, a prominent marker of attentional goal maintenance, in high versus low performers of task switching. It was found that P300 amplitude was independent of behavioral rigidity in psychosis patients, but these two measures were positively associated in the healthy group, indicating a path to cognitive alteration in the psychosis etiology that neither of the measures alone would be able to capture. This study left unanswered questions regarding the brain activity underlying flexible task switching, so chapter 4 introduced a novel task paradigm which recorded electroencephalography (EEG) while healthy young adults performed set switching tasks which occurred in the ocular motor domain. This paradigm design was equipped with improved experimental control compared to other available tasks, and it allowed complete spatial and temporal mapping of voltage events occurring in the brain during successful task switching. Together, these studies generated novel information about the brain processes behind inhibition, action selection and cognitive flexibility.