Language and Cognitive Functions in a Neurological Tumour Population: A Long- Term Follow-up Study by Katherine Fowler A thesis submitted to Victoria University of Wellington in fulfilment of the Requirements for the degree of Doctor of Philosophy in Psychology Victoria University of Wellington 2018 Abstract Complex cognitive capacities such as language and “executive function” are difficult to evaluate in neuropsychological populations due to their multifactorial nature. The current study takes a cognitively-motivated core-skills approach to their assessment. Across four investigations, these various capacities are decomposed into simpler core skills based on current cognitive theory. An undifferentiated sample of 28 neurological tumour patients is then assessed on these skills. In the first study, we assessed the “core skills” underpinning language function at three time points: pre-operative (one day prior to surgery), post-operative (within three days of surgery), and at long-term follow-up (at least three months post-surgery). This approach was sensitive at detecting impairment; indeed, almost half of the patients showed persistent long-term language deficits even at long-term follow-up. The decompositional approach also proved effective at predicting long-term outcomes. Overall, these results suggest that the subtle language deficits may be more common and more persistent than previously estimated in tumour populations. The second study examined the relationship between “core” language skills and sentence- level language processing at long-term follow up. Whilst there were few significant correlations, the results nonetheless suggest that “core skills” measures may be useful predictors of some aspects of sentence-level processing. The third study isolated and identified “core” skills that are essential for complex cognitive control more generally, and assessed these in our patient sample at long-term follow-up. Results were broadly supportive of this decompositional approach, and again, our assessments proved highly sensitive at detecting deficits in this patient sample. The fourth study examined the relationship between language processing and complex cognitive control. Specifically, we examined whether there are systems specially dedicated to the control of language, or whether control functions operate across all domains. Overall, our results were broadly consistent with the domain-specific view - that there may be functionally distinct control systems operating on verbal and nonverbal material. The results, taken together suggest that a core skills approach to neuropsychological assessment has considerable promise, and is worth exploring further in a large patient sample. This approach may also help extend our understanding of the functional organisation of language, and the broader cognitive skills necessary for linguistic operations. i Acknowledgements It was truly a privilege to be involved in this project, and there are a number of people who made this possible. First, I would like to thank each of the patients and their families for their generous time and willingness to be involved in this project. I am enormously grateful and humbled that they allowed me to be a small part of their journey during what was an extremely difficult time in their lives. Thank you for being so open. I have learnt an enormous amount from working these patients, which I will carry throughout my personal and clinical life. To my primary supervisor, Dr Carolyn Wilshire. I simply cannot thank you enough for your endless guidance, expertise, support, and humour throughout this project. It has truly been a privilege to work with you and learn from you. Thank you for always encouraging me and having faith in me. I would also like to thank Mr. Andrew Parker for his involvement in this project. Also, to Josh Faulkner, whose research formed the basis for this project – thank you for your constant support and guidance, and your genuine interest in my research. To my lab mates and those in the clinical programme, particularly Emma Ashcroft, Samuel Clack, Victoria Lee, and Kris Neilson, thank you for your unwavering support, encouragement and humour throughout this journey. Also, to my friends, particularly Kate Norman and Catherine Pihema, thank you for listening and supporting me, providing me with endless cups of coffee when I needed it, and picking me up when times were tough. To my parents, Jennie and Ray, thank you for your unconditional support, encouragement, and constant reassurance when I was convinced I couldn’t do it. Thank you for listening to me, proofreading my thesis, and always encouraging me to follow my passion, no matter how hard the journey. Without you, this would have been much harder. Finally, to my partner Jake who has been on this journey with me from the beginning. I simply cannot thank you enough for your unwavering love and support. Thank you for keeping the home fires burning, sharing the burden with me, celebrating the joy, and encouraging me to follow my dreams. You have been my biggest cheerleader and support and I truly couldn’t have done this without you by my side. This thesis is dedicated to the patients and their families who sadly lost their battle – each of whom selflessly gave up their precious time in the hope that it will help others. I hope that can be fulfilled. ii Table of Contents Abstract ...................................................................................................................................... 2 Acknowledgements .................................................................................................................... 3 Table of Contents ....................................................................................................................... 4 Chapter 1: Overview of Language and Cognitive Theories ...................................................... 3 Chapter 2: Long-Term Language Outcomes in Tumour Patients ............................................ 23 Introduction .......................................................................................................................... 23 Method ................................................................................................................................. 58 Results .................................................................................................................................. 77 Discussion .......................................................................................................................... 105 Chapter 3: Core Skills and Complex Language ..................................................................... 115 Introduction ........................................................................................................................ 115 Method ............................................................................................................................... 128 Results ................................................................................................................................ 135 Discussion .......................................................................................................................... 148 Chapter 4: Characterising Cognitive Control ........................................................................ 155 Introduction ........................................................................................................................ 155 Method ............................................................................................................................... 167 Results ................................................................................................................................ 180 Discussion .......................................................................................................................... 191 Chapter 5: The Relationship between Language and Cognitive Control .............................. 199 Introduction ........................................................................................................................ 199 Method ............................................................................................................................... 212 Results ................................................................................................................................ 215 Discussion .......................................................................................................................... 230 Chapter 6: ............................................................................................................................... 234 General Discussion ............................................................................................................ 234 Appendix A: ........................................................................................................................... 249 Appendix B: ........................................................................................................................... 263 Appendix C: ........................................................................................................................... 275 Appendix D: ........................................................................................................................... 282 Appendix F: ........................................................................................................................... 297 References