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Brain. 2016 Jun;139(Pt 6):1817-29. doi: 10.1093/brain/aww067. Epub 2016 Apr 9.

Core auditory processing deficits in primary progressive aphasia.

Author information

1
1 Institute of Neuroscience, Medical School, Newcastle University, Newcastle-upon-Tyne, UK 2 Machine Learning Group, Department of Computer Science, Berlin Institute of Technology, Berlin, Germany.
2
3 Laboratory for Cognitive Neurology, KU Leuven Department of Neurosciences, Belgium 4 Neurology Department, University Hospitals Leuven, Leuven, Belgium.
3
3 Laboratory for Cognitive Neurology, KU Leuven Department of Neurosciences, Belgium.
4
4 Neurology Department, University Hospitals Leuven, Leuven, Belgium.
5
1 Institute of Neuroscience, Medical School, Newcastle University, Newcastle-upon-Tyne, UK 6 Wellcome Centre for Neuroimaging, University College London, UK.
6
3 Laboratory for Cognitive Neurology, KU Leuven Department of Neurosciences, Belgium 4 Neurology Department, University Hospitals Leuven, Leuven, Belgium 7 Alzheimer Research Centre KU Leuven, Leuven research Institute for Neuroscience and Disease, University of Leuven, Belgium rik.vandenberghe@uz.kuleuven.ac.be.

Abstract

The extent to which non-linguistic auditory processing deficits may contribute to the phenomenology of primary progressive aphasia is not established. Using non-linguistic stimuli devoid of meaning we assessed three key domains of auditory processing (pitch, timing and timbre) in a consecutive series of 18 patients with primary progressive aphasia (eight with semantic variant, six with non-fluent/agrammatic variant, and four with logopenic variant), as well as 28 age-matched healthy controls. We further examined whether performance on the psychoacoustic tasks in the three domains related to the patients' speech and language and neuropsychological profile. At the group level, patients were significantly impaired in the three domains. Patients had the most marked deficits within the rhythm domain for the processing of short sequences of up to seven tones. Patients with the non-fluent variant showed the most pronounced deficits at the group and the individual level. A subset of patients with the semantic variant were also impaired, though less severely. The patients with the logopenic variant did not show any significant impairments. Significant deficits in the non-fluent and the semantic variant remained after partialling out effects of executive dysfunction. Performance on a subset of the psychoacoustic tests correlated with conventional verbal repetition tests. In sum, a core central auditory impairment exists in primary progressive aphasia for non-linguistic stimuli. While the non-fluent variant is clinically characterized by a motor speech deficit (output problem), perceptual processing of tone sequences is clearly deficient. This may indicate the co-occurrence in the non-fluent variant of a deficit in working memory for auditory objects. Parsimoniously we propose that auditory timing pathways are altered, which are used in common for processing acoustic sequence structure in both speech output and acoustic input.

KEYWORDS:

pitch; progressive non-fluent aphasia; rhythm; semantic dementia; timbre

PMID:
27060523
PMCID:
PMC4892752
DOI:
10.1093/brain/aww067
[Indexed for MEDLINE]
Free PMC Article

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