Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Neuroscience

Supervisor

Culham, Jody C.

2nd Supervisor

Anderson, Michael L.

Co-Supervisor

Abstract

In naturalistic settings, brains continuously interface with a dynamic and interactive external environment. The inclusion of such an environment in an fMRI study is difficult, given the practical constraints imposed by the machine itself. This study sought to test whether the ecological validity of fMRI could be enhanced by testing a new paradigm that incorporated a dynamic and interactive virtual environment (DIVE). To determine the viability of this paradigm, functional connectivity was assessed during a DIVE condition and compared to functional connectivity patterns acquired in conditions with equally dynamic stimuli but that lacked interactivity with the environment. This study found significant differences in functional connectivity between the DIVE condition and non-interactive conditions, suggesting that control within an environment may have a major impact on patterns of brain activation. Further, this may also suggest that DIVE paradigms could be viable candidates for increasing the ecological validity of fMRI experiments.

Summary for Lay Audience

Environments, in the real-world, are in constant flux. They change and shift based on events occurring not only external to us, but also as a result of actions we take within them. But when we interact with objects in our environment, the external world isn’t the only thing that changes. Perceptions of our world change in response to the effects within our environment. These changes affect how our brain functions, which in turn, can change the way we interface with our environment. One of the major difficulties in neuroimaging is trying to balance controlled experimentation with real-world conditions. If the conditions of an experiment are too far removed from those found in real-world conditions, it can be difficult to create substantive models of how the brain functions. Functional magnetic resonance imaging (fMRI) is a type of neuroimaging in which incorporating environments and interactive agency is particularly difficult, given the practical constraints of the technology; subjects must remain motionless, supine and confined within a narrow tube. The goal of this study was to bring some fundamental elements of a natural environment—dynamism and agency—into the fMRI setting to see whether the brain acts differently than it does when compared to the conditions normally found in these studies. To circumvent the practical barriers of fMRI, I used a video game—Pac-man—as a dynamic and interactive virtual environment (DIVE). This study found significant differences in functional connectivity between the DIVE condition and non-interactive conditions, suggesting that control within an environment may have a major impact on the way the brain functions when in contexts closer to real-world conditions. My hope is that this study illustrates the utility of using the DIVE paradigm in the neuroimaging space—in particular, fMRI—to bring more real-world conditions into the toolkit for studying brains and how they operate.

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