Abstract
IntroductionProsody has been little studied in the primary progressive aphasias (PPAs), a group of neurodegenerative disorders presenting with progressive language impairment. MethodsHere we conducted a systematic investigation of different dimensions of prosody processing (acoustic, linguistic and emotional) in a cohort of 19 patients with nonfluent PPA syndromes (11 with progressive nonfluent aphasia, PNFA; five with progressive logopenic/phonological aphasia, LPA; three with progranulin-associated aphasia, GRN-PPA) compared with a group of healthy older controls. Voxel-based morphometry (VBM) was used to identify neuroanatomical associations of prosodic functions. ResultsBroadly comparable receptive prosodic deficits were exhibited by the PNFA, LPA and GRN-PPA subgroups, for acoustic, linguistic and affective dimensions of prosodic analysis. Discrimination of prosodic contours was significantly more impaired than discrimination of simple acoustic cues, and discrimination of intonation was significantly more impaired than discrimination of stress at phrasal level. Recognition of vocal emotions was more impaired than recognition of facial expressions for the PPA cohort, and recognition of certain emotions (in particular, disgust and fear) was relatively more impaired than others (sadness, surprise). VBM revealed atrophy associated with acoustic and linguistic prosody impairments in a distributed cortical network including areas likely to be involved in perceptual analysis of vocalisations (posterior temporal and inferior parietal cortices) and working memory (fronto-parietal circuitry). Grey matter associations of emotional prosody processing were identified for negative emotions (disgust, fear, sadness) in a broadly overlapping network of frontal, temporal, limbic and parietal areas. ConclusionsTaken together, the findings show that receptive prosody is impaired in nonfluent PPA syndromes, and suggest a generic early perceptual deficit of prosodic signal analysis with additional relatively specific deficits (recognition of particular vocal emotions).
Highlights
Prosody has been little studied in the primary progressive aphasias (PPAs), a group of neurodegenerative disorders presenting with progressive language impairment
Demographic and neuropsychological data are summarised in Table 1: the PPA group performed significantly worse than controls on all tests, while the only significant difference between the disease subgroups was more impaired single word comprehension in LPA compared with progressive nonfluent aphasia (PNFA) and lower forwards digit span in GRN-PPA compared to the other subgroups
The PNFA and GRN-PPA subgroups were significantly worse than controls on all subtests apart from stress discrimination (Table 2)
Summary
Primary progressive aphasia (PPA) is a group of neurodegenerative disorders which presents with impairment of language (Mesulam, 2001, 2003). Several canonical subtypes have been identified: semantic dementia (SD), led by verbal semantic impairment; progressive nonfluent aphasia (PNFA), led by, apraxia of speech and agrammatism; progressive logopenic/. We conducted a systematic investigation of different dimensions of prosody processing (acoustic, linguistic and emotional) in a cohort of patients with PPA versus healthy older control subjects. For the purposes of this study, we focus on nonfluent variants of PPA rather than SD. Patients with nonfluent PPA (unlike patients with SD) show deficits in the perceptual analysis of nonverbal environmental sounds (Goll et al, 2010): the nonfluent PPA variants are the logical initial target for an investigation of prosody processing. We used voxel-based morphometry (VBM) to identify neuroanatomical associations of prosodic functions in the nonfluent PPA syndromes
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