Learning and episodic memory following childhood brain tumour : a case study

This thesis presented the case of an adolescent boy, CJ (age at diagnosis: 11: 1 0 years, age range at time of assessment: 13:07 - 16:08), who became amnesic as a consequence of a metastatic central nervous system malignancy and subsequent treatment. Survivors of childhood brain tumours often acquire complex cognitive difficulties, however, extreme memory disorders consistent with an amnesic condition are rarely reported in this clinical population. Neuropsychological assessment of CJ indicated a profound and global memory impairment in the context of well preserved premorbid semantic knowledge and verbal skills (Chapter 2). Thus, CJs neuropsychological profile afforded questions relevant to the fractionation of human memory from a functional perspective. A central question of the research presented here was whether CJs amnesia could be described in classic dichotomies of long-term memory. The experiments presented in this thesis adopted a classical neuropsychology framework to examine episodic and semantic memory with particular attention to relative preservation of function. Throughout this thesis CJ's performance was compared to a carefully selected group of control participants. Results showed that CJ was capable of demonstrating novel semantic learning in the absence of a functional episodic memory system (Chapter 2). Related to this, the focus of Chapter 3 was to ascertain Cl's deficit in contextual memory relative to item memory. Consistent with the adult amnesia literature, CJ was generally able to report whether or not an item was presented, however, he permanently failed at accurately reporting the source characteristics of the learning episode. A number of experiments demonstrated that CJ was unable to benefit from encoding conditions that facilitate elaborative processing, including self-generation (Chapter 4) and deeper semantic processing (Chapter 5; Chapter 6). He did however learn semantically related materials more effectively, and was also able to build up a strong gist representation based on pre-existing semantic relationships (Chapter 5). An emergent finding of this thesis is that CJ's memory largely relies on automatic processes in the complete absence of recollection (Chapter 6). Consistent with this, his memory was best under conditions where gains in performance could be achieved through fluent processing (Chapter 6) and implicit memory (Chapter 7). Results are discussed in terms of contemporary dichotomies of long-term memory and clinical relevance. Finally, future directions for research in the growing field of neuropsycho-oncology are outlined.EThOS - Electronic Theses Online ServiceGBUnited Kingdo