<p>Semantic memory is part of the long-term memory system, and there are several theories concerning this type of memory. Some of these will be described in this essay. There are also several types of neuropsychological semantic memory deficits. For example, test results have shown that patients tend to have more difficulties naming living than nonliving things, and one probable explanation is that living things are more dependent on sensory than on functional features. Description of concrete concepts is a new test of semantic memory, in which cueing is used, both to capture the maximum performance of patients, and to give insight into the access versus storage problem. The theoretical ideas and empirical results relating to this new test will be described in detail. Furthermore, other tests of semantic memory that have been commonly used will also be briefly described. In conclusion semantic memory is a complex cognitive system that needs to be studied further.</p>

The aim of the present doctoral thesis was to investigate the ability of patients with Alzheimer's disease (AD) to utilize cognitive support in order to improve episodic remembering. A review of previous research indicated that most studies have failed to find beneficial effects of encoding support on memory in AD patients. The ability to utilize cognitive support (i.e., motoric activities, semantic organization, and semantic knowledge) for episodic remembering was investigated in five studies (Bäckman &amp; Herlitz, 1990; Herlitz, Adolfsson, Bäckman, &amp; Nilsson, in press; Herlitz &amp; Bäckman, 1990; Herlitz &amp; Viitanen, in press; Karlsson et al., 1989). Patients with mild, moderate, or severe AD, and normal older adults participated in the studies. On the basis of the results from these studies and the review of the literature, it was concluded that (a) AD patients, irrespective of dementia severity, perform at a lower level than normal older adults in episodic memory tasks; (b) provided that support is supplied at retrieval, AD patients may be sensitive to manipulations at encoding; (c) the strength of the encoding manipulation determines the size of the memory improvement in AD patients; and (d) depending on dementia severity, the type of encoding support also determines the magnitude of memory improvement obtained. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1991, härtill 5 uppsatser.</p> / digitalisering@umu

Most of the work investigating the representation of concrete nouns in the brain has focused on the locations that code the information. We present a model to study the contributions of perceptual and semantic features to the neural code representing concepts over time and space. The model is evaluated using magnetoencephalography data from different paradigms and not only corroborates previous findings regarding a distributed code, but provides further details about how the encoding of different subcomponents varies in the space-time spectrum. The model also successfully generalizes to novel concepts that it has never seen during training, which argues for the combination of specific properties in forming the meaning of concrete nouns in the brain. The results across paradigms are in agreement when the main differences among the experiments (namely, the number of repetitions of the stimulus, the task the subjects performed, and the type of stimulus provided) were taken into consideration. More specifically, these results suggest that features specific to the physical properties of the stimuli, such as word length and right-diagonalness, are encoded in posterior regions of the brain in the first hundreds of milliseconds after stimulus onset. Then, properties inherent to the nouns, such as is it alive? and can you pick it up?, are represented in the signal starting at about 250 ms, focusing on more anterior parts of the cortex. The code for these different features was found to be distributed over time and space, and it was common for several regions to simultaneously code for a particular property. Moreover, most anterior regions were found to code for multiple features, and a complex temporal profile could be observed for the majority of properties. For example, some features inherent to the nouns were encoded earlier than others, and the extent of time in which these properties could be decoded varied greatly among them. These findings complement much of the work previously described in the literature, and offer new insights about the temporal aspects of the neural encoding of concrete nouns. This model provides a spatiotemporal signature of the representation of objects in the brain. Paired with data from carefully-designed paradigms, the model is an important tool with which to analyze the commonalities of the neural code across stimulus modalities and tasks performed by the subjects.

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.