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Publication

Feature-based attention in a dynamically changing and ageing world

Book - Dissertation

In a fast-paced world where our senses are bombarded by sensory information, selective attention prevents our brain from being overloaded by prioritising behaviourally relevant stimuli (= targets) over irrelevant stimuli (= distracters). Top-down attentional processes allow us to voluntarily select targets in the visual scene by enhancing one or multiple locations based on features (e.g., colour) while suppressing others. The original aim of this doctoral project was to better understand feature-based attention in the ageing human brain. However, the research on ageing in the doctoral project is limited due to restrictions during the COVID-19 pandemic. First, we investigated the neural mechanisms of feature-based attention by combining functional magnetic resonance imaging (fMRI) with a dynamic feature-based sustained attention to response task (SART) that minimises the contribution of spatial processes. We found that feature-based attention is supported by regions of the fronto-parietal dorsal attention network (DAN) (Chapter 2). In a follow-up study, we demonstrated that regions of the DAN and the visual cortex are modulated by feature-based attentional weighting (Chapter 3). We did not obtain evidence in favour of the DAN as top-down source of attention signals to visual regions, but its direct or indirect (e.g., coupling with the inferior frontal junction) involvement is likely. Second, we investigated age-related changes in feature-based attention. Research on healthy ageing has huge potential to enhance our understanding of cognitive functions and to improve the quality of life in the fast-growing old population. To assess behavioural differences in feature-based attention between younger and older adults, we compared their performance on a feature-based two-alternative forced choice task. We observed that feature-based attention declines with age, likely due to a reduced top-down suppression of distracters (Chapter 4). Third, we studied context-based factors that might impact feature-based attention. More specifically, we assessed whether the spatial offset between and spatial configuration of a target and a distracter affect performance on the feature-based SART. Our findings suggest that performance does not depend on the location of a distracter relative to a target (Chapter 5). In addition, we investigated whether attending to different features affects behaviour. We developed a SART with sinusoidal gratings to (re-)assess sustained attention, for instance in subjects with an impaired ability to process alphanumerical stimuli. We showed that the performance of healthy individuals on the SART with sinusoidal gratings is only moderately different from and correlates with performance on the SART with digits, and that both variants are sensitive to cognitive impairments of cases with acquired brain injury (Chapter 6). In sum, this thesis contributes to knowledge on the neural mechanisms of feature-based attention and how it is affected by individual and context-based characteristics.
Publication year:2022
Accessibility:Closed