Macquarie University
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Balancing stimulus and goal-driven attentional demands: investigating the role of gamma oscillations in human early visual cortex using magnetoencephalography

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posted on 2022-03-29, 03:51 authored by Loes Koelewijn
"Salient events tend to capture our attention. When such events are irrelevant to something we are looking for they need to be inhibited not to distract us. Efficient allocation of attention involves balancing of attentional demands driven by both salient events and current goals. To deal with the constantly changing visual input in light of attentional goals, it is crucial that visual brain areas participate in this balancing. The aim of this thesis is to investigate the role of early visual areas in the balancing of stimulus and goal-driven attentional demands. I primarily focus on the synchronisation of oscillatory activity in the gamma band, because its role in both neural communication and visual processing makes it a prime candidate for mediating the dynamic balancing of attentional demands. In Chapter 1 I review the literature on behavioural effects and neural processing of attentional demands. In Chapter 2, I focus on how evoked responses in early visual cortex are modulated when stimulus salience and behavioural relevance compete for attentional allocation. I then address how these factors interact to modulate gamma activity in three steps. In Chapter 3, I use a strong gamma-inducing stimulus to investigate how orientation, a stimulus property strongly represented in early visual cortex, affects the gamma response. In Chapter 4, I investigate how directing voluntary attention towards or away from that optimal stimulus affects the gamma response it induces. Finally, I address how stimulus and goal-driven factors combine to influence the gamma response when they compete for attentional allocation in Chapter 5. The main findings in this thesis are that stimulus and goal-driven factors influence gamma synchronisation in early visual cortex at different frequencies, and interact to modulate the gamma response when attentional demands are actively balanced. These findings contribute to our understanding of the role of early visual cortex in both low-level and attentional visual processing. I address the implications of these findings in Chapter 6." -- Abstract.


Table of Contents

1. General introduction -- 2. Manipulating behavioural relevance of a salient item: an MEG -- 3. Induced and evoked neural correlates of orientation selectivity in human visual cortex -- 4. Sustained visuo-spatial attention increases high-frequency gamma synchronisation in human medial visual cortex -- 5. Investigating effects of stimulus salience and behavioural relevance on gamma synchronisation in early visual cortex -- 6. General discussion -- Appendix.


"This thesis is presented for the degree of Doctor of Philosophy (PhD), August 2012" Includes bibliographical references Thesis by publication.

Awarding Institution

Macquarie University

Degree Type

Thesis PhD


PhD, Macquarie University, Faculty of Human Sciences, ARC Centre of Excellence in Cognition and its Disorders, Department of Cognitive Science

Department, Centre or School

Department of Cognitive Science

Year of Award


Principal Supervisor

Anina Rich


Copyright disclaimer: Copyright Loes Koelewijn 2013.




1 online resource (xii, 233 pages) illustrations (some coloured)

Former Identifiers

mq:37442 2134354