Behavioural and physiological correlates of sustained attention and its improvement via transcranial random noise stimulation

Thesis

Maintaining focus on one task over long periods is known as sustained attention, which supports higher order cognition such as learning. Suboptimal sustained attention is characterised by poor task performance, response variability, and task disengagement. Cortical and subcortical mechanisms of arousal and cognitive control modulate moment-to-moment changes in sustained attention. This thesis investigates the relationships between baseline markers of sustained attention, including behaviour, pupil dynamics, and cortical markers, during low and high demand. Furthermore, I test their utility in the context of transcranial random noise stimulation (tRNS) as a way to predict sustained attention benefits in young adults. My first results from a secondary analysis using a continuous sustained attention task with tRNS, indicated that high baseline response variability was the better predictor of performance gains from tRNS, compared to sham tRNS. Next, in a series of online and lab-based experiments, I investigated changes in performance and thought experiences. Using an airplane monitoring paradigm with and without distractors, I also examined pupillary correlates of task conditions and performance. The results indicated that distractors impacted accuracy negatively but facilitated stable responses. Pupil dilation was observed during increased task load, decreased performance, and greater perceived task-focus compared to mind wandering (MW) in line with predictions of increased arousal. Finally, a tRNS, electroencephalography, and eye-tracking experiment suggested an overall benefit of tRNS on sustained attention during a monotonous task. In addition, participants with low baseline accuracy were predicted to benefit the most, independent of task demands. Pupil size indicated arousal-related differences between MW and task focus, as well as between response variability during low and high task demand. This work contributes insights into the relationship between sustained attention, MW, arousal, and performance improvements during tRNS. Moreover, it uses this knowledge to highlight the importance of behavioural markers to predict the attentional benefits from tRNS.

Authors: Karstens, MI

• DOI: 10.5287/ora-jb00vdzj1
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: vigilance; sustained attention; arousal; visual search; mind wandering; response variability; transcranial random noise stimulation; tRNS
• Subjects: Physiology; Attention; Brain stimulation