j 2806391479 Episodic Memory for Emotional Information: Event-Related Potential and Functional Magnetic Resonance Imaging Studies Elizabeth Jayne Maratos 2001 Thesis for the Degree of Doctor of Philosophy in Psychology University College London ProQuest Number: 10010400 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest. ProQuest 10010400 Published by ProQuest LLC(2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. Microform Edition © ProQuest LLC. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 Abstract The neural correlates of emotional episodic memory are investigated in a series of neuroimaging experiments (ERP, fMRI) through the comparison of memory effects elicited during retrieval of emotional relative to neutral information. In the first two ERP studies, it is revealed that emotionally-valenced words influence recognition memory primarily by virtue of their high levels of ‘semantic-cohesiveness’. Furthermore, the findings reveal that the arrangement of emotional and neutral retrieval cues at test (blocked versus intermixed) influences processing carried out upon retrieved emotional episodic information. The findings across the third and fourth ERP studies indicate that incidental retrieval of emotional context (encoding environment) gives rise to greater activity in neural systems supporting episodic retrieval than does retrieval of non-emotional context. When context retrieval is intentional, by contrast, emotional and non-emotional episodic memory are associated with equivalent levels of engagement. The findings of the fourth ERP study are consistent with the existence of additional neural circuitry that is activated selectively by emotionally toned episodic information. In a final event-related fMRI study it is revealed that the retrieval of emotionally negative relative to emotionally neutral context elicits enhanced activity in brain regions including prefrontal cortex, amygdala, hippocampus and retrosplenial cortex. Recognition of words from positive relative to neutral contexts is associated with increased activity in prefrontal and orbitofrontal cortex, and in the left anterior temporal lobe. The fMRI findings provide further support for the proposal that the incidental retrieval of emotional information enhances activity in networks supporting episodic retrieval of neutral information. In addition, the fMRI findings suggest that regions known to be activated when emotional information is encountered in the environment are also active when emotional information is retrieved from memory. Whilst the findings are noteworthy in their own right, they also have implications for future studies of emotional memory. It is proposed that the employment of paradigms which involve the retrieval of emotional context through presentation of non-emotional retrieval cues may offer advantages over paradigms wherein the retrieval cues themselves are emotional. Declaration for the Degree of Ph.D. (i) I Elizabeth Jayne Maratos hereby certify that this thesis, which is approximately 70, 000 words in length, has been written by me, that it is a record of work carried out by me, and that it has not been submitted in any previous application for a higher degree. date signature of candidate (ii) I was admitted as a research student in October 1997 and as a candidate for the degree of Doctor of Philosophy in October 1997; the higher study for which this is a record was carried out in the University of St. Andrews between 1997 and 1998, and the University College London between 1998 and 2000. date signature of candidate (iii) I hereby certify that the candidate has fulfilled the conditions of the Resolution and Regulations appropriate for the degree of Doctor of Philosophy in the University College London and that the candidate is qualified to submit this thesis in application for that degree. date signature of supervisor Acknowledgements Acknowledgements are made first to members of the St. Andrews and UCL psychology departments who have provided friendship, support and advice. I would like to thank especially, past and present members of the Cognitive Electrophysiology Group (formerly the Wellcome Brain Research Group) who, without exception, have been fantastic to work alongside. I would like to express my gratitude to Mick for his supervision and support which has been both constant and attentive. To my family and Daniel, the biggest thanks of all. ABSTRACT.................................................................................................................................................... 2 FOREWORD................................................................................................................................................ 14 CHAPTER 1 ................................................................................................................................................. 16 Episodic Memory ..........................................................................................................................................16 Introduction ............................................................................................................................................... 16 Models of Memory ....................................................................................................................................16 Indirect and Direct Tests of Memory ................................................................................................. 19 Processing Theories .............................................................................................................................21 Process Purity ...................................................................................................................................... 22 The Neuroanatomical Basis of Episodic Memory Retrieval ................................................................. 24 Theories of Recognition Memory ............................................................................................................27 Summary.................................................................................................................................................... 32 CHAPTER 2 ................................................................................................................................................. 34 Event-Related Potentials.............................................................................................................................34 Background ................................................................................................................................................ 34 Methodology ..............................................................................................................................................37 Electrogenesis: Potential Generation and Fields ...............................................................................37 Experimental Design ............................................................................................................................40 ERP Recording .................................................................................................................................... 41 Artefact Contamination and Signal Averaging .................................................................................42 Analysis and Interpretation of ERP measurements ................................................................................45 Physiological versus Functional Approaches .................................................................................... 45 Source Localisation ..............................................................................................................................47 Quantitative versus Qualitative Distinctions ..................................................................................... 49 Data Analysis........................................................................................................................................50 Summary.................................................................................................................................................... 53 CHAPTER 3 ................................................................................................................................................. 54 Event-Related Neuroimaging of Memory ............................................................................................... 54 ERP studies of Memory ............................................................................................................................54 The Left Parietal Effect........................................................................................................................55 Old/new Effects and Dual Processing Models .................................................................................. 57 The Right Frontal Effect and Retrieval Processing ............................................................................ 64 Event-Related fMRI ....................................................................................................................................67