Investigating the suitability of neurofeedback to improve fatigue

Hanzal, Simon (2025) Investigating the suitability of neurofeedback to improve fatigue. PhD thesis, University of Glasgow.

Abstract

Fatigue is an adverse subjective state occurring during demanding tasks, often coupled with vigilance decrements and changes in the associated brain signal oscillations. Surveys indicate age-related imbalances in fatigue, making older age groups a viable target to investigate fatigue in the healthy population.

In this thesis, I examined fatigue during sustained attention decline (as reflected in vigilance decrements), both behaviourally and neurally, across young and olderage groups. Electroencephalographic metrics of increases in alpha and other lower frequency oscillations, both pre-stimulus and in relation to the task, were of particular interest. These oscillations have been previously associated with vigilance decrements and used in neurofeedback interventions targeting fatigue symptoms. I also examined motivational factors potentially contributing to the age-related effects. Using different adaptations of the Sustained Attention to Response Task (SART), three empirical studies examined how fatigue manifests in performance and neural activity across the young and healthy older samples.

Chapter 2 demonstrated that the SART can induce subjective fatigue and that this change relates to accuracy change. However, its key finding was a higher accuracyin older adults, with only limited age-specific fatigue effects. In Chapter 3, an extended version of the SART including extensive EEG measures additionally revealed neural changes over time commonly associated with fatigue (increased pre-stimulus alpha and task-related beta synchronization), but these were correlated neither to subjective fatigue nor to a performance decline. Instead,
age again emerged as the primary drive of the behavioural and neural responsesto the task, further showing a prospective link to motivation. In Chapter 4, I thusshifted focus from time-on-task to testing possible motivational effect directly. Young and older participants were equalised to the same accuracy level by titration of task difficulty. Initially, higher motivation helped older participants match the young group's performance. Then, following an unexpected motivational initiative, young participants became motivated and showed larger accuracy improvement compared to the older group. Fatigue had little impact on
performance or age effects.

I conclude that sustaining attention over time can incur a subjective experience of fatigue, but an accompanying shift in neural oscillations is uncorrelated and likely only reflects covert changes in attentional processes. My findings thus challenge the assumption of a tight coupling of fatigue to performance declineand neural pattern changes in sustained attention. This also casts doubt on the efficacy of neurofeedback treatments of fatigue by targeting these patterns. Instead, I highlight the interplay of age and motivation as drivers of performance(and brain dynamics) during sustained attention and posit them as a more promising focus for future interventional research.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: B Philosophy. Psychology. Religion > BF Psychology; R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Funder's Name: Economic and Social Research Council (ESRC)
• Supervisor's Name: Harvey, Professor Monika, Learmonth, Dr. Gemma and Thut, Professor Gregor
• Date of Award: 2025
• Depositing User: Theses Team
• Unique ID: glathesis:2025-85365
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 07 Aug 2025 14:45
• Last Modified: 07 Aug 2025 14:56
• Thesis DOI: 10.5525/gla.thesis.85365
• URI: https://theses.gla.ac.uk/id/eprint/85365

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