The cognition of non-verbal sound in dementia.
Doctoral thesis, UCL (University College London).
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A growing body of functional imaging studies provides considerable insight into cortical networks for non-verbal auditory processing. However, determination of the essential cognitive and anatomical components of these networks depends upon the study of damaged brains, and yet, auditory neuropsychology is little studied and poorly understood. Whilst naturally occurring lesions that selectively disrupt auditory processes are rare, increasing evidence suggests that degenerative diseases target functional networks implicated in non-verbal auditory processing. Furthermore, a small but significant auditory neuropsychological literature shows that dementia can lead to impairments of non-verbal sound processing. This thesis comprises a series of studies designed to reveal deficits of non-verbal auditory processing in four distinct dementia syndromes: three variants of primary progressive aphasia (semantic dementia, SD; progressive non-fluent aphasia, PNFA; logopenic aphasia, LPA), and typical Alzheimer’s disease (AD). The first two studies (Chapters 2 and 3) involve the development of two novel non-verbal auditory neuropsychological batteries, including tests to examine perceptual property, apperceptive, and semantic stages of processing; the subsequent use of these batteries reveals syndrome-specific profiles of non-verbal auditory impairment. Next, a detailed psychoacoustic assessment of two single cases (Chapter 4) provides evidence for specific disorders of auditory property and object processing. A further study (Chapter 5) comprises the examination of non-verbal auditory object processing in SD using functional magnetic resonance imaging (fMRI); results suggest that auditory object recognition depends upon a distributed temporo-parietal network involving closely associated mechanisms of perceptual and semantic processing. Finally, novel neuropsychological assessments are used to reveal the selective impairment of auditory scene analysis in AD (Chapter 6). Together, these neuropsychological findings provide novel insights into the organisation of cortical networks for non-verbal auditory cognition.
|Title:||The cognition of non-verbal sound in dementia|
|Open access status:||An open access version is available from UCL Discovery|
|Additional information:||Copyright restricted material comprising of two published journal articles has been removed from the e-thesis.|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Neurology > Neurodegenerative Diseases|
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