A fundamental aspect of our existence is the fact that we live in a spatially extended world. To survive and flourish in this world, we must have some method for navigating efficiently from place to place. The current project focuses on the neural mechanisms that underlie landmark- based navigation (LBN)?navigation that is guided by spatially stable elements of the environment. To implement LBN, a person must be able to 1) perceive the local environment, 2) use features of the local environment to determine their location and orientation in the world, and 3) plan a route that takes them from their current location to their navigational goal. In previous funding periods, we have used functional magnetic resonance imaging (fMRI) and other methods to identify regions of the human brain that mediate these operations and to assign functional roles to these regions. Now we seek to integrate these findings to understand how these neural/cognitive components work together to implement LBN during realistic navigational episodes.
In aim 1 we will identify the spatial representations that are simultaneously active in the human brain during dynamic navigation, including representations of location and heading, and representations of the navigational goal.
In aim 2 we seek to understand the remapping mechanisms that allow a navigator to negotiate a complex world that contains multiple local environments.
In aim 3 we will delineate the reorientation mechanisms that allow a navigator to establish (or re-establish) their sense of place and direction after losing their bearings. Together, these operations?knowing where we are in the world and the location of our goal, distinguishing between different spatial environments, and recovering our bearings when we are disoriented?constitute core elements of spatial navigation. Understanding the neural mechanisms that underlie these elements would be a major and sustained intellectual advance in an area that has long been a central topic of investigation in psychology and neuroscience.

Public Health Relevance

This project aims to understand the neural mechanisms underlying spatial navigation. The knowledge gained from this research will be important for developing rehabilitation strategies and assistive devices for people with impaired sight, who often suffer from navigational difficulties. Moreover, because the brain regions that we plan to study are often impacted by normal aging, stroke, and neurodegenerative diseases such as Alzheimer's dementia, knowledge about these regions will be useful for diagnosing these conditions and mitigating the memory problems and navigational challenges that often occur with them.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
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Cognition and Perception Study Section (CP)
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Flanders, Martha C
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University of Pennsylvania
Schools of Arts and Sciences
United States
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Julian, Joshua B; Kamps, Frederik S; Epstein, Russell A et al. (2018) Dissociable spatial memory systems revealed by typical and atypical human development. Dev Sci :e12737
Julian, Joshua B; Keinath, Alexandra T; Frazzetta, Giulia et al. (2018) Human entorhinal cortex represents visual space using a boundary-anchored grid. Nat Neurosci 21:191-194
Keinath, Alexandra T; Epstein, Russell A; Balasubramanian, Vijay (2018) Environmental deformations dynamically shift the grid cell spatial metric. Elife 7:
Bonner, Michael F; Epstein, Russell A (2018) Computational mechanisms underlying cortical responses to the affordance properties of visual scenes. PLoS Comput Biol 14:e1006111
Julian, Joshua B; Keinath, Alexandra T; Marchette, Steven A et al. (2018) The Neurocognitive Basis of Spatial Reorientation. Curr Biol 28:R1059-R1073
Vass, Lindsay K; Epstein, Russell A (2017) Common Neural Representations for Visually Guided Reorientation and Spatial Imagery. Cereb Cortex 27:1457-1471
Bonner, Michael F; Epstein, Russell A (2017) Coding of navigational affordances in the human visual system. Proc Natl Acad Sci U S A 114:4793-4798
Keinath, Alex T; Julian, Joshua B; Epstein, Russell A et al. (2017) Environmental Geometry Aligns the Hippocampal Map during Spatial Reorientation. Curr Biol 27:309-317
Marchette, Steven A; Ryan, Jack; Epstein, Russell A (2017) Schematic representations of local environmental space guide goal-directed navigation. Cognition 158:68-80
Epstein, Russell A; Patai, Eva Zita; Julian, Joshua B et al. (2017) The cognitive map in humans: spatial navigation and beyond. Nat Neurosci 20:1504-1513

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