Hidden Patterns: Hippocampal Acquisition of Spatial Regularities during Navigation
Date of Award
Fall 2023
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Psychology
First Advisor
Turk-Browne, Nicholas
Abstract
The role of the hippocampus in supporting navigation has been examined across species for decades, elucidating single-unit, ensemble, and region-level functions for representing and negotiating space. However, how these functions arise in humans, interact with other hippocampally driven processes, and emerge in the real world, remains underexplored. Across five studies, I fill these theoretical gaps using behavioral, computational, and human electrophysiological methods, and argue that navigation is not merely another function of the hippocampus but that it directly interfaces with known statistical learning and associative encoding processes. In Chapter 2, I first establish behaviorally that search behavior during virtual navigation is subject to influence from statistical regularities in the environment. Then, via a rare opportunity to longitudinally test a single intracranial EEG patient, I implicate the hippocampus in reflecting these learned statistics in Chapter 3, and seat this role within the larger phenomena of pattern extraction across time by juxtaposing it with the more protracted role of the medial prefrontal cortex in representing extracted statistical representations. In Chapter 4, I address a central limitation of Chapters 2 and 3 -- the reliance on virtual analogues to navigation instead of ecologically valid ambulation in the real world. Using cutting-edge methodology that enables acquisition of human electrophysiology data during real-world ambulation, I first provide foundational evidence of hippocampal codes for movement onset and navigation speed, direction, and location. Building on these findings, in Chapter 5 I demonstrate the relationship between these navigation mechanisms and hippocampal associative memory functions by showing that the signals arising during real-world ambulation are not circumscribed only to physical movement, but can be bound to arbitrary sensory cues and subsequently reinstated in the absence of movement. Finally, building on this foundation, in Chapter 6 I situate pattern extraction during navigation within a real-world environment. I demonstrate that, as was shown in virtual navigation, participants successfully acquire statistics during naturalistic navigation, and these learned statistical representations are reliably represented in the hippocampus such that they can be reinstated via an arbitrary sensory cue. Collectively, this work demonstrates a novel interaction between hippocampal functions that may support adaptive navigation in a world rich with regularities.
Recommended Citation
Graves, Kathryn Nicole, "Hidden Patterns: Hippocampal Acquisition of Spatial Regularities during Navigation" (2023). Yale Graduate School of Arts and Sciences Dissertations. 1206.
https://elischolar.library.yale.edu/gsas_dissertations/1206
