Event typicality and memory: Investigating how prior knowledge and novelty modulate memory for complex events by Kyra Lynn McKelvey A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Department of Psychology University of Toronto © Copyright by Kyra McKelvey 2016 Event typicality and memory: Investigating how prior knowledge and novelty modulate memory for complex events Kyra Lynn McKelvey Doctor of Philosophy Department of Psychology University of Toronto 2016 Abstract A complex set of processes and brain regions work together in healthy adults, allowing them to create and recall memories of daily events. Additionally, the perception and recall of these events is shaped by factors such as novelty and congruence with prior knowledge (typicality). Despite a long history of research, studies on the neural underpinnings of the mnemonic effects of novelty and typicality rarely examine complex naturalistic event memories. Moreover, it is uncertain how these effects evolve over time, as memories are stabilized and transformed from acquisition to retention and retrieval. In this thesis I use naturalistic film clip stimuli, behavioural measures, and functional magnetic resonance imaging (fMRI) to explore the effects of both novelty and typicality on the neural substrates mediating memory, and examine how these effects evolve through encoding and retrieval over the course of a week. Behaviourally, I find that both typicality and novelty enhance memory for events, but that atypical events are recalled with more errors over time. With respect to the neural bases of memory, I demonstrate that the greatest differences based on event typicality are seen during encoding - when typicality is correlated with greater medial prefrontal cortex (mPFC) and parietal activation, while novelty is correlated with greater activation in the medial temporal lobes (MTLs) and posterior sensory cortices. During retrieval, however, such differences based on typicality are subtler, with ii retrieval supported by the MTLs, irrespective of event typicality, at all time points. Notwithstanding these overall neural similarities in the retrieval of all events, typical clips are associated with attenuated MTL activation during remote retrieval, indicating that recall dynamics may be influenced by event typicality over time. Furthermore, I provide evidence for differential functional connectivity of both the mPFC and MTLs during encoding and retrieval, based on event typicality. These results, which demonstrate how the neural substrates mediating narrative episodic memories are modulated by event typicality, are consistent with two complementary theories - Trace Transformation Theory and Schema Theory. Furthermore, they suggest, through mPFC and MTL functional connectivity, potential mechanisms by which typical and novel events may be differentially encoded and retrieved. iii Acknowledgments I would like to express my deepest appreciation for my supervisor, Dr. Morris Moscovitch, who has guided, encouraged, and challenged me throughout my graduate studies, provided generous opportunities for my continual growth, and supported me on both an academic and personal level. I would like to thank all the members of the Moscovitch lab for their advice and support, particularly Dr. Melanie Sekeres. I am also grateful for the thoughtful questions, comments, and advice from the members of my committee, Dr. Asaf Gilboa and Dr. Cheryl Grady. Finally, I’d like to thank my wonderful husband for all of his support and encouragement, and for always being there for me. iv Table of Contents Acknowledgments .......................................................................................................................... iv Table of Contents .............................................................................................................................v List of Tables ............................................................................................................................... viii List of Figures ................................................................................................................................ ix List of Appendices ........................................................................................................................ xii Chapter 1 Introduction .....................................................................................................................1 1.1 Introduction ..........................................................................................................................1 1.1.1 Prior knowledge and memory ..................................................................................2 1.1.2 Neural correlates for the interaction of prior knowledge with episodic memory ....5 1.1.3 Novelty, memory, and the medial temporal lobes ...................................................7 1.1.4 mPFC-MTL connections and interactions ...............................................................9 1.1.5 Consolidation and memory over time ....................................................................12 1.1.6 Consolidation and schemas ....................................................................................14 1.1.7 Alternative Theories of mPFC function .................................................................16 1.2 Dissertation Objectives ......................................................................................................17 1.2.1 Broad objectives .....................................................................................................17 1.2.2 Specific hypotheses ................................................................................................18 Chapter 2 Materials and Methods ..................................................................................................21 2.1 Participants .........................................................................................................................21 2.2 Stimuli ................................................................................................................................21 2.3 fMRI data acquisition ........................................................................................................22 2.4 Experimental procedure .....................................................................................................23 v 2.5 Data Analysis .....................................................................................................................25 2.5.1 Scoring and behavioural analyses ..........................................................................25 2.5.2 fMRI data preprocessing ........................................................................................26 2.5.3 fMRI data analyses: general ...................................................................................26 2.5.4 fMRI data analyses: parametric analyses ...............................................................27 2.5.5 fMRI data analyses: direct contrasts ......................................................................28 2.5.6 fMRI data analyses: functional connectivity .........................................................28 2.5.7 fMRI data analyses: region of interest (ROI) analyses ..........................................30 2.5.8 Analysis of brain-behaviour correlations ...............................................................31 2.6 Organization of Results ......................................................................................................31 Chapter 3 Behavioural Effects of Event Typicality .......................................................................33 3.1 Results ................................................................................................................................33 3.2 Interim Discussion .............................................................................................................36 Chapter 4 Neural Substrates mediating the encoding of typical and atypical events ....................38 4.1 Results ................................................................................................................................38 4.1.1 Average results .......................................................................................................38 4.1.2 Parametric results ...................................................................................................39 4.1.3 Direct contrast results ............................................................................................40 4.1.4 Functional connectivity results ..............................................................................41 4.2 Interim Discussion .............................................................................................................44 4.2.1 The mPFC, MTLs, and the encoding of events .....................................................44 4.2.2 Perceptual processing during event encoding ........................................................46 4.2.3 The posterior cingulate cortex and the encoding of typical events ........................47 4.2.4 mPFC-MTL functional connectivity ......................................................................48 Chapter 5 Neural substrates mediating the retrieval of typical and atypical events ......................50 5.1 Results ................................................................................................................................50