Systems Neuroscience Models of Human Oculomotor Orienting
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Authors
Coutinho, Jonathan
Date
2024-10-04
Type
thesis
Language
eng
Keyword
saccade , pursuit , pupil , perception , cognition , action , motor control
Alternative Title
Abstract
Orienting behaviour is an example of active perception: the coordination of body movements to control the acquisition of sensory information from the environment. Oculomotor orienting includes movements of the eyes to redirect gaze and adjustments of pupil size to modulate the quantity and quality of light entering the eye. Chapter 2 investigates human visual tracking through the development of a dynamical systems model bringing together a variety of theoretical insights from research in perception, decision-making, and motor control. Visual tracking is characterized by two complementary types of eye movements: smooth pursuit to continuously stabilize image motion, and saccades to discretely reposition visual images onto the fovea. This study demonstrates how predictive, probabilistic control can explain pursuit-saccade behaviour and I discuss how insights from this model can generalize towards broader principles for the neural control of coordinated movements. Chapters 3 and 4 investigate the control of pupil size during variations in environmental luminance. Chapter 3 describes the analysis of pupil behaviour, quantifying nonlinearities and variability stimulus-response metrics. We found two conserved relationships across individuals: between pupil size and pupil gain (i.e. diameter change per log-unit luminance change), and between transient response metrics (i.e. peak diameter change and peak velocity – the pupil main sequence). Chapter 4 develops a novel model of the sensory-motor processing underlying luminance-evoked pupil dynamics accounting for the physical optics of sensory feedback and the nonlinearities of iris muscle dynamics. We found that across-participant variability can be explained by luminance-independent tonic motor commands (and not differences in luminance sensitivity), which results in behavioural correlated covariability between pupil size and gain through muscle nonlinearities. Together, Chapters 3 and 4 provide a foundation for making inferences about the neural control of pupil behaviour. Future research can build upon this foundation to investigate changes in luminance-evoked pupil control during aging or neurological disorders and the cognitive control of pupil size while accounting for nonlinearities in muscle biomechanics and physical optics and confounding from luminance variation. Collectively, the research in this thesis advances our understanding of human vision, cognition, and motor coordination, as well as providing analytical tools for future research.
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Attribution-NonCommercial-NoDerivatives 4.0 International
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivatives 4.0 International