Spatial Information Modulates the Neurocognitive Dynamics of Episodic Autobiographical Memory Retrieval by Melissa Hebscher A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Department of Psychology University of Toronto © Copyright by Melissa Hebscher, 2018 Spatial Information Modulates the Neurocognitive Dynamics of Episodic Autobiographical Memory Retrieval Melissa Hebscher Doctor of Philosophy Department of Psychology University of Toronto 2018 Abstract Episodic autobiographical memory (EAM) enables reliving past experiences, recalling the sensory information associated with that event. Spatial information is thought to play an early and important role in EAM, contributing to the dynamics of retrieval. Using a combination of behavioural, neuroimaging, and neurostimulation approaches, this dissertation aimed to examine the temporal dynamics of EAM and the role spatial information plays in its retrieval. Chapter 2 demonstrated a temporal precedence for spatial information at the behavioural level, but importantly found high individual variability in early recall of spatial information. Further, individual differences in spatial aspects of EAM were reflected in hippocampal and precuneus grey matter volumes. Chapter 3 examined the temporal dynamics of EAM at the neural level using magnetoencephalography (MEG). While cueing individuals with familiar locations altered the dynamics of retrieval, it did not confer an early neural advantage. Together with the findings from Chapter 2, these results indicate that early spatial information alters the dynamics of EAM retrieval, but does not play a ubiquitous or automatic role in EAM. This study also found that spatial perspective during EAM retrieval was associated with a well-established neural component of episodic memory recollection. Transcranial magnetic stimulation (TMS) administered to the precuneus disrupted this association, demonstrating that this region is crucially involved in neural processing of spatial perspective during EAM. In Chapter 4, I ii assessed how regions representing spatial information, such as the precuneus and medial temporal lobe (MTL), interact dynamically during EAM retrieval. Using MEG to measure oscillatory activity, this study found that theta (3-7 Hz) and high gamma (65-85 Hz) oscillations underlie MTL-parietal communication, demonstrating the importance of coupling between theta and gamma oscillations in EAM. TMS to the precuneus disrupted this oscillatory activity, suggesting that this region plays a causal role in network-wide theta and gamma oscillatory activity. Together, these studies elucidate the behavioural and neural dynamics of EAM retrieval, as well as spatial contributions to EAM. Future research is needed to further clarify the key contributions of specific regions and the dynamic activity underlying widespread neural communication during EAM. iii AcKnowledgments I would like to thank my supervisor, Dr. Asaf Gilboa, for his consistent support, thoughtful advice, and encouragement over the years. I am lucky to have a supervisor who showed me such kindness and patience, and from whom I learned so much. I am also grateful to Dr. Brian Levine for his continued guidance and feedback, and for welcoming me to his lab meetings which, among other things, taught me to critically evaluate research. I would also like to thank my committee member Dr. Morgan Barense for providing helpful comments and insightful questions. Thank you also to Dr. Jed Meltzer for teaching me and encouraging me to develop techniques and skills fundamental to my research. I am grateful for the friends I have made in the department, who have made my time in graduate school so much more enjoyable and meaningful. I am confident we will remain friends, despite the different paths our lives may take. I owe special thanks to Christian for love, patience, and laughter during this process. Thank you for taking a vested interest in my work, listening to me complain, and always encouraging me. Thank you also for reminding me to stop working when necessary- to travel, go for a walk, read a book, and to have fun. Finally, I would like to thank my wonderful family, whose belief and pride in me has been a major motivating force throughout this process. To my grandparents, Roz, Sam, Sylvia, and Sid, thank you for trying to understand what I do, for cutting out newspaper articles about the brain for me, and for always believing in me. I am especially grateful to my parents, Dale and Steve, and my sister Danielle for their unfaltering love, support, and encouragement. I could not have done this without you. iv Table of Contents Acknowledgments .......................................................................................................................... iv Table of Contents ............................................................................................................................ v List of Tables ................................................................................................................................. ix List of Figures ................................................................................................................................. x List of Appendices ....................................................................................................................... xiv Chapter 1 General Introduction ...................................................................................................... 1 1.1 Overview ......................................................................................................................... 1 1.2 Medial temporal lobes and memory ............................................................................... 2 1.3 Retrieval dynamics of EAM ........................................................................................... 5 1.4 Parietal cortex and EAM ................................................................................................. 6 1.5 Individual differences in EAM ....................................................................................... 9 1.6 Transcranial magnetic stimulation ................................................................................ 10 1.6.1 Mechanisms of action ............................................................................................... 11 1.6.2 TMS investigation of the parietal cortex .................................................................. 12 1.6.3 Challenges to using TMS .......................................................................................... 13 1.7 Neural oscillations ........................................................................................................ 14 1.7.1 Altering neural oscillations ....................................................................................... 17 1.8 Present research ............................................................................................................ 18 Chapter 2 Individual differences in episodic autobiographical memory relate to precuneus and hippocampal grey matter volumes ................................................................................................ 20 2.1 Introduction ................................................................................................................... 20 2.2 Materials and Methods .................................................................................................. 22 2.2.1 Participants ................................................................................................................ 22 2.2.2 Episodic autobiographical memory .......................................................................... 22 2.2.3 Survey of Autobiographical Memory (SAM) ........................................................... 24 2.2.4 MRI data acquisition ................................................................................................. 25 2.2.5 Behavioural data analysis ......................................................................................... 25 2.2.6 Anatomical analyses ................................................................................................. 27 v 2.2.7 Exploratory analyses ................................................................................................. 29 2.3 Results ........................................................................................................................... 30 2.3.1 Behavioural results .................................................................................................... 30 2.3.2 Anatomical results .................................................................................................... 34 2.4 Discussion ..................................................................................................................... 38 2.4.1 Behavioural findings ................................................................................................. 38 2.4.2 Anatomical findings .................................................................................................. 40 2.4.3 Limitations ................................................................................................................ 42 2.4.4 Conclusions ............................................................................................................... 42 Chapter 3 Temporal dynamics of retrieval: ERF correlates of episodic autobiographical memory ......................................................................................................................................................