Behavioural and neuroimaging approaches to understanding the neurocognitive basis of real-world spatial navigation

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Memory of our spatial environment is crucial for daily life. We rely on spatial memory to get around at home and in the world, and to locate objects and buildings; without spatial memory, we literally would be lost. This proposal is concerned with how we represent large-scale indoor and outdoor environments in memory as we gain experience navigating within them. Forming spatial memories of new environments depends on the hippocampus, a brain structure deep in the temporal lobes that changes as we get older. Once we become very familiar with an environment, spatial memory of that environment is preserved after hippocampal damage and instead relies on other brain structures, such as parietal cortex. However, spatial memories that are highly detailed and precise continue to depend on the hippocampus. This pattern of results suggests that we form a "gist" or "schema" outside of the hippocampus that preserves the geometry of an environment, but not its visual features (e.g., colours, trees), serving as a template for future encounters with the same or similar environments. One way to test this idea is to determine the extent to which modifying visual features and/or geometry of a newly learned or highly familiar environment affects wayfinding. These effects might also be seen in changes to viewing behaviour and to activity within and outside of the hippocampus. We will combine eye tracking and functional magnetic resonance imaging (fMRI) with virtual reality (VR) to characterize navigation in young adults and older adults, as aging is associated with changes to hippocampal structure and function. Participants will receive a series of virtual wayfinding tasks, implemented in detailed 3D models of York University and Baycrest Hospital campuses that can be rendered and visualized in 1st-or 3rd-person in real-time using Unity 3D. This will allow us to provide participants with a fully immersive experience during wayfinding in both outdoor and indoor environments, and to selectively manipulate specific features to assess the effects on wayfinding. We will examine activity within and outside of the hippocampus during task performance and compare performance to self-reported navigation ability and navigation strategy preference. Canada has a rich history in the area of cognitive neuroscience and is regarded as an international leader in memory research. It is important to maintain this status through the specialized training of students in developing basic theory and effective applications of innovative technologies such as fMRI for examining brain function. Findings from this research will lead to a greater understanding of the cognitive makeup of spatial memory, how it relates to non-spatial memory, and how it is represented in the human brain.