Wernicke’s aphasia (WA), an acquired impairment of language comprehension and word repetition, results from a cerebrovascular accident to the left temporoparietal junction. The disorder has been important to the development of neurobiological models of language, however neuropsychological investigations into the nature of the comprehension impairment have been limited. This thesis presents a series of four experiments, investigating the comprehension impairment in WA. Chapter 3, a behavioural neuropsychological study, investigates existing hypotheses of the comprehension impairment in WA: a phonological breakdown, a semantic breakdown, a dual phonological-semantic breakdown. A case series comparison methodology is utilised. Participants with WA are compared to participants from two other clinical, comprehension impaired groups: semantic dementia and semantic aphasia. Semantic dementia and semantic aphasia provide neuropsychological models of semantic breakdown, affecting semantic representations and semantic control respectively. Individuals with WA showed disrupted non-verbal semantic analysis of a similar magnitude to that in semantic dementia and semantic aphasia and of a qualitatively similar nature to that in semantic aphasia. A significantly greater impairment on assessments which required acoustic-phonological analysis was found for individuals with WA compared to semantic aphasia. Overall a dual breakdown in acoustic-phonological and semantic control best accounted for the comprehension impairment in WA. In Chapter 4, direct evidence was sought for a link between acoustic-phonological non-word analysis and auditory comprehension in WA. A novel test of non-word discrimination was created which was perceptually graded so as to provide a sensitive measure in severely impaired participants. Individuals with WA were significantly impaired at non-word discrimination compared to age and hearing matched control participants who performed at ceiling. The degree of non-word discrimination/acoustic-phonological analysis impairment correlated with auditory comprehension in WA. Chapter 5 investigated the extent to which the established acoustic-phonological impairment in WA was grounded in a more fundamental deficit in non-verbal auditory analysis. The capacity to detect structural changes in non-verbal auditory stimuli was measured. Participants with WA had an impaired capacity to detect differences in all but the most structurally simple auditory stimuli, compared to control participants. The degree of this impairment correlated with the degree of auditory comprehension impairment in the WA group. Chapter 6 revisits the semantic impairment observed in WA. Functional magnetic resonance imaging was used to investigate the residual neural networks recruited by individuals with WA, when performing a semantic animate-inanimate judgment task. Large portions of the inferior and anterior temporal lobes bilaterally were activated, regions remote from the lesion in WA. Age matched control participants recruited similar regions; however the activation in WA participants was significantly stronger. This indicated greater reliance on the residual semantic network in WA in response to damage to posterior temporoparietal semantic regions. The results from this series of studies indicated that the primary deficit in WA is one of impaired acoustic analysis and co-morbid damage to a phonological system. Additional disruption occurs to the semantic control network, which regulates the task directed use of semantic representations. A combination of all three factors accounts for the comprehension impairment in WA and it is the relative contributions of each factor that accounts for behavioural variation between individuals.

This thesis investigated the role of the anterior temporal lobes (ATLs) in conceptual knowledge and name relearning by studying people with semantic dementia (SD). People with SD have atrophy focussed on the ATLs and they exhibit a pan-modal semantic impairment (e.g., Hodges, Patterson, Oxbury, & Funnell, 1992). Recent evidence suggests that modality-invariant concept representations are built up in the ATLs and that these modality-invariant representations are crucial for abstracting away from the surface features of items in order to generalise conceptual information based on their core semantic similarity (e.g., Lambon Ralph & Patterson, 2008). In order to test this, two of the studies described in this thesis (Chapters 2 and 3) assessed semantic generalisation in people with SD. These studies showed that people with SD are less able to generalise conceptual information on the basis of the deeper semantic structure of concepts but instead are increasingly influenced by the superficial similarity of the items. These studies support the hypothesis that the modality-invariant representations formed in the ATLs are crucial for semantic-based generalisation. Previous SD relearning studies have reported relatively good learning but a lack of generalisation to untrained items, tasks, and/or contexts (i.e., under-generalisation). This has been interpreted based on the Complementary Learning Systems (CLS) (McClelland, McNaughton, & O'Reilly, 1995) to suggest that the neocortical semantic system no longer makes a meaningful contribution to relearning but instead relearning is primarily dependent upon the sparse representational medial temporal lobe (MTL) learning system. The studies described in two of the thesis chapters (Chapters 4 and 5) investigated the role of the underlying systems further and found that the neocortical semantic system does still contribute to relearning in SD (although its contribution is disordered and based on the degraded concept representations in the ATL) but there is a shift in the division of labour such that the MTL system takes over more of the work. Finally, in order to clarify the outcomes of relearning in SD, Chapter 6 reviewed all of the previous SD relearning studies and confirmed that people with SD are able to relearn the specific information that they study but that this relearning is rigid. The review and a subsequent re-analysis of the data from Chapters 4 and 5 also showed that relearning in SD can have negative side-effects as well as positive effects.

In children with well-developed handwriting, handwriting speed is more strongly related to orthographic coding—the speed at which they can access verbal codes (SAVC) in memory— than fine motor speed. Only one study has investigated this relationship in an adult population (Peverly et al., 2014). This dissertation is a replication of that study, using archival data collected during two prior studies. Two separate groups of students from an undergraduate university (Study 1, N = 147; Study 2, N = 94) completed measures of handwriting speed (Studies 1 and 2: a modified Alphabet Writing Task from Detailed Assessment of Speed of Handwriting 17+), fine motor speed (Study 1: Digit Symbol Copy task from the WAIS-III; Study 2: Diagonal Line task developed by Peverly et al., 2014), SAVC (Study 1: an adapted Verbal Fluency measure from the NEPSY; Study 2: RAN-A designed by Denckla & Cutting, 1999), language comprehension (Study 2: Nelson-Denny Reading Test), working memory (Study 1 and 2: Listening Span Test developed by Daneman & Carpenter, 1980), and executive attention (Study 2: group administered Stroop Color and Word Test). In the analysis, handwriting speed (DV) was regressed on all other variables (IVs) in each study. In Study 1, three variables significantly and positively predicted handwriting speed: fine motor speed, compositional fluency, and SAVC (semantic retrieval only). Because of the measure of SAVC used in this study, the construct was split between phonetic retrieval and semantic retrieval. In Study 2, only fine motor speed and SAVC were positively predictive. Despite the differences in measurement between Study 1 and Study 2, the relationship between handwriting speed, SAVC, and fine motor speed remained consistent. Overall, these results lend further support to the conclusion of Peverly et al. (2014) that the relationship between fine-motor fluency and SAVC to handwriting speed is consistent beyond childhood and is evident in an adult population.

This paper demonstrates how transformer language models can be improved by giving them access to relevant structured data extracted from a knowledge base. The knowledge base preparation process and modifications to transformer models are explained. We evaluate these methods on language modeling and question answering tasks. These results show that even simple additional knowledge augmentation leads to a reduction in validation loss by 73%. These methods also significantly outperform common ways of improving language models such as increasing the model size or adding more data.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19272号 / 医博第4036号 / 新制||医||1011(附属図書館) / 32274 / 京都大学大学院医学研究科医学専攻 / (主査)教授 高橋 淳, 教授 村井 俊哉, 教授 渡邉 大 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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Consumer decisions are largely influenced by prior experiences via memory. Consumer research is limited in its consideration of the separate memory system conceptualisations dominant in psychology, and rather has primarily focused on semantic memory (SM). As Autobiographical Memory (AM) may equally affect one’s brand consumption decisions, it is critical to integrate AM into brand-related memory studies for a complete understanding of the consumer learning and decision-making process. The study conceptualises affective, self-relevant brand episodes as Brand-Related Autobiographical Memory (BRAM), and storage of abstract brand knowledge as Brand-Related Semantic Memory (BRSM). The conceptual review identified hypothesised relationships between BRAM, BRSM, self-brand congruence and affective brand commitment. Within a positivist paradigm, the study employed methodological triangulation with qualitative interviews, functional magnetic resonanace imaging (fMRI) experiment and a survey to collect data. Findings suggest that brand memories are stored in AM and SM, and brand memories that are in AM are self-relevant and emotion-laden. The construct of Specificity explains the self-brand congruence relationship while BRAM (Vividness and Affect) influence brand commitment. No relationship was discovered between BRSM, self-brand congruence and brand commitment. This is of particular significance as dominant consumer research focuses on semantic memory. The research contributes to marketing theory by: 1). identifying the importance of multiple memory systems in understanding consumers’ decision-making; 2). exploring how BRAM contributes towards emotional decision-making models; 3). identifying the importance of BRAM in self-brand congruence theory and brand commitment decisions; 4). demonstrating the use of nuroimaging (fMRI) methods to study consumer memories and 5). introducing the BRAM scale as a complementary measure to recall and recognition tests.

The present study examined the possibility that reading books might support declarative memory, and potentially contribute to the cognitive reserve and thereby minimize age-related decline in memory functions. It was a crosssectional study, where data were taken from 566 Betula Study participants, as well as the scores of declarative memory assessment tasks, and book reading reports. The tasks of episodic memory were sentence learning with and without encoding enactment –free and cued recall. The tasks of semantic memory were word fluency, initial letter A, M fivewords, B profession names, and SRB –vocabulary. Three-way analysis of variance was performed for hypothesis testing. The results showed that book reading might support declarative memory. There was a significant relationship between education and book reading. Was not found if book reading might minimize age-related decline. In conclusion, the study showed that book reading and years of education might support declarative memory. / Denna studie undersökte om läsandet av böcker stödjer deklarativt minne, och eventuellt främjar den kognitivareserven, vilket medför en minimerad åldersbaserad reduktion i minnesfunktioner. I denna tvärsnittsstudie ingick datafrån 566 deltagare i Betulaprojektet som testats med avseende på deklarativa minnesfunktioner, samt enlitteraturanalys. Utvärderingarna som baserades på episodiskt minne var; menings-inlärning med och utan 'encodingenactment' -både fri och stödd återgivning. Test av semantiskt minne var ordflöde med första bokstav A, M fem-ord,B yrkesnamn, och SRB-ordförråd. Tre-vägs variansanalyer genomfördes för hypotestestning. Resultaten visade på enkoppling mellan utbildning och läsandet av böcker. Det är dock fortfarande oklart om läsandet av böcker minimeraråldersbaserad minnes-reducering. Sammanfattningsvis, visade studien att läsning och utbildning kan stödja deklarativtminne.

People with a diagnosis of schizophrenia have been found to perform poorly on tasks assessing semantic memory, and these impairments have been proposed to be related to certain symptoms, in particular Formal Thought Disorder (FTD). A systematic literature review and meta-analysis identified the need a) to determine whether semantic memory is a primary impairment in schizophrenia and not secondary to other cognitive impairments and b) what cognitive models could provide the best explanation for the impairment. With these aims, Studies One and Two compared the performance of a group of people with schizophrenia across a battery of semantic memory tests (Hodges, Salmon and Butters, 1992). In order to eliminate confounding variables, two clinical control groups were recruited for comparison, one with a probable degraded semantic memory arising from Alzheimer‘s Dementia (AD) and the other with a primary dysexecutive syndrome caused by acquired brain injury (ABI). From these comparisons, it was possible to profile the semantic memory impairment in schizophrenia with the conclusion that any deficits are task-specific. Unlike the AD group, the impairment did not seem to arise from a loss of stored knowledge but nor did a retrieval problem, in its simplest terms, offer the best explanation. Since the ABI group performed normally on the battery it is clear that a dysexecutive syndrome does not necessarily explain poor semantic memory performance. Qualitatively, the associations and categories formed by people with schizophrenia on tasks of semantic categorisation e.g. the Category Generation Test (CGT) (Green, Done, Anthony, McKenna and Ochocki, 2004) often resemble loosening of associations and psychotic speech. In order to understand more about the processes involved in the formation of these bizarre categories, I compared performance on the CGT of groups of people with schizophrenia, AD and ABI. I found that the people with AD performed fairly similarly to the people with schizophrenia in that they sorted cards in an idiosyncratic way but the ABI group performed normally, adhering to taxonomic categories. Although this result might suggest that the bizarre associations on the CGT in people with schizophrenia are caused by a deficit in semantic memory (and not a dysexecutive syndrome), further analysis found important differences between the AD and the schizophrenia group in the way the card sorts were formed. In addition, both these groups showed intact semantic memory knowledge of the items they mis-sorted, indicating that categorisation problems do not necessarily arise from a degraded memory store. The difficulties people with schizophrenia appear to have on tests of associations and categorisation (e.g. CGT) could arise from a disorganised semantic memory i.e. differences in the way in which concepts are interconnected. On the CGT, patients with schizophrenia were far more likely to sort items on the basis of thematic (situational) information suggesting a preference for thematic over taxonomic associations. To test this, participants were tested using a triadic comparison task which requires choosing whether an item is best associated with a taxonomic, thematic or perceptually related item. On this test patients performed comparably to controls suggesting that their semantic memory is organised normally and that the abnormalities in the way in which items are associated on some semantic memory tests, including the CGT, are task-specific. It has been proposed that one of the core problems in schizophrenia is that there is ―an aberrant assignment of salience‖ (Kapur 2003) to contextually inappropriate concepts due to a dysregulated dopamine system (Kapur 2003; Kapur et al 2005). It is possible that this could also explain the semantic memory impairments in schizophrenia i.e. certain less relevant concepts/ associations are chosen because they are experienced as more salient. To test this, a group of patients with schizophrenia were assessed using a test of semantic salience. Compared to controls, the patients made significantly more errors of salience including significantly more errors where large aberrant attributions of importance were given to items. The tendency to make errors on the salience test was highly correlated with errors on the CGT and also the semantic association tests, indicating a common underlying mechanism. Therefore, it can be concluded that the semantic memory impairments in schizophrenia are task-specific, not caused by a loss of semantic knowledge or a dysexecutive syndrome, but due to an aberrant assignment of salience to less relevant semantic concepts. More work is needed to understand the cognitive processes underlying this aberrant attribution process, and also the biological substrates involved.

L'une des capacités humaines fondamentales est la capacité d'interpréter des symboles. Malgré plusieurs décennies de travaux en neuropsychologique et neuroimagerie sur le substrat cognitif et neuronal des représentations sémantiques, de nombreuses questions restent sans réponse. Les présents travaux de thèse tentent de démêler l'un de ces mystères: les substrats neuronaux des différentes composantes du mot sont-ils dissociables? Ce travail comporte deux composantes principales : l'une théorique et l'autre empirique. Dans la première partie, nous passons en revue les différentes positions théoriques concernant les corrélats cognitifs et neuraux des représentations sémantiques. De plus, nous proposons une distinction opérationnelle entre les dimensions moto-perceptives (c'est-à-dire les attributs des objets auxquels les mots se réfèrent perçus par les sens) et conceptuelles (c'est-à-dire l'information construite par l'intégration des multiples caractéristiques perceptives). Dans la deuxième partie, nous présentons les résultats des études menées afin d'étudier l'automaticité de la récupération, l'organisation topographique et la dynamique temporelle des dimensions moto-perceptives et conceptuelles de la signification des mots. Tout en contribuant à notre compréhension de la manière dont le sens des mots est codé dans le cerveau, les travaux présentés dans cette thèse ont des implications méthodologiques et théoriques importantes. En particulier, ils soulignent l'importance d'une intégration fructueuse entre les théories cognitives et les méthodes statistiques avancées afin d'éclairer les mystères entourant les représentations sémantiques. / One of the core human abilities is that of interpreting symbols. Notwithstanding decades of neuropsychological and neuroimaging work on the cognitive and neural substrate of semantic representations, many questions are left unanswered. The research in this dissertation attempts to unravel one of them: are the neural substrates of different components of concrete word meaning dissociated? In the first part, I review the different theoretical positions and empirical findings on the cognitive and neural correlates of semantic representations. Crucially, I propose an operational distinction between motor-perceptual dimensions (i.e., those attributes of the objects referred to by the words that are perceived through the senses) and conceptual ones (i.e., the information that is built via a complex integration of multiple perceptual features). In the second part, I present the results of the studies I conducted in order to investigate the automaticity of retrieval, topographical organization, and temporal dynamics of motor-perceptual and conceptual dimensions of word meaning. The results suggest that the neural substrates of different components of symbol meaning can be dissociated in terms of localization and of the feature of the signal encoding them, while sharing a similar temporal evolution.