Barnett, Benjamin;
(2024)
Characterising the neural correlates of perceptual experience.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Perceptual experiences are fundamental to the human condition, and yet how experiences arise in the brain remains unknown. This thesis examines various aspects of conscious awareness to better characterise how perceptual experiences are generated in the brain. In an initial study, I analyse magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) data to test whether established properties of neural magnitude codes extend to the neural processes governing reports of awareness and vividness. Using multivariate decoding and representational similarity analysis, I report how a content-invariant code supports perceptual vividness judgements and how this code extends across visual and frontoparietal regions of the brain. The second experiment extends these findings to the concept of numerical absence. This chapter provides the first neuroscientific exploration of the number zero in the human brain and establishes zero’s place on a neural number line that is independent of numerical format. This study relates to perceptual experience by providing support for an account of the relationship between basic sensory absences and more complex conceptual absences. In a third study, I analyse the fMRI data of patients with Alzheimer’s disease to assess whether classic neural markers of awareness are altered in the disorder. I report that neural correlates of awareness are diminished in Alzheimer’s disease and use this to argue for its characterisation as a disorder of consciousness, not just of memory. Finally, I provide the first validation of newly developed optically pumped MEG (OP-MEG) systems in a naturalistic social perception task. Across a series of analyses, I was unable to reproduce previously established neural markers of perspective-taking in a real-world task and discuss the reasons why this may have been the case. Overall, this thesis presents a number of novel insights into the neural basis of perceptual experience. It contributes empirical tests of candidate theories of consciousness, assessments of perceptual experience in disease, and, finally, ushers in a new era of ecological tests of awareness.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Characterising the neural correlates of perceptual experience |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Div of Psychology and Lang Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Div of Psychology and Lang Sciences > Institute of Cognitive Neuroscience UCL |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10201265 |
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