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Word Stress Representation in Parkinson’s Disease: Evidence for Selective Impairment of Prosodic Rule Knowledge
Poster Session E, Friday, October 2, 11:00 am - 1:00 pm, Wangari Maathai
Julia Nieslony1, Veronika Motzko3, Ulrike Domahs1, Frank Domahs2; 1Marburg University, 2University of Erfurt, 3University Medical Center of the Johannes Gutenberg University Mainz
Deficits in word stress production in patients with Parkinson’s disease (PD) have typically been attributed to speech motor impairments associated with dysarthria. However, it remains unclear whether these deficits also reflect impairments in the representation of prosodic knowledge. The present study systematically investigates word stress in PD across perception, production, and representation, with a particular focus on the integrity of rule-based versus lexical prosodic knowledge. The study included 12 individuals diagnosed with PD and eight neurotypical controls matched by age, gender and level of education. All participants completed a task battery targeting the perception, production, and representation of word stress. Basal auditory processing and word stress perception of the subjects were tested using tone differentiation tasks and the auditory discrimination of minimal pairs of words and pseudowords. Production was investigated by asking participants to read multisyllabic words and pseudowords aloud. This task not only provided a basis for the characterization of word stress production in individuals with PD in comparison to neurotypical controls but moreover enabled a direct comparison between the lexical knowledge employed when producing existing words and the prosodic rule-based knowledge that comes into play when assigning word stress to pseudowords. Prosodic representation was further assessed using a sequence reproduction task. Participants reproduced sequences of pseudowords forming minimal pairs that either differed in prosodic stress (experimental condition) or in a single consonant (control condition). As this design necessitates the temporary storage and reconstruction of phonological patterns, it offers a precise measure of prosodic representation independent of lexical knowledge. Mixed effects models revealed a dissociation in performance across cognitive levels. At the perceptual level, no significant differences were observed between the PD group and controls, suggesting intact processing of auditory stress cues. In production, acoustic and perceptual analyses revealed that for both participant groups, stress assignment for words was unremarkable. However, patients with PD produced unexpected stress patterns with pseudowords, suggesting an impairment of prosodic rule knowledge. In the sequence reproduction task, testing phonological representations, the PD group performed worse than the control group. Specifically, patients with PD exhibited difficulties with the suprasegmental prosodic condition (stress minimal pairs) compared to the segmental control condition (consonant minimal pairs), achieving significantly poorer results in the former. These findings demonstrate that word stress deficits in PD extend beyond the difficulties experienced with the phonetic marking in the context of dysarthria, into the domain of linguistic representation. Difficulties in word stress marking can thus be attributed not only to speech motor impairments but also to deficient linguistic knowledge regarding stress assignment. Selective impairment in pseudoword production and prosodic sequence reproduction as opposed to retained stress production for real words suggests a specific deficit in rule-based prosodic knowledge, while lexical knowledge of word stress remains relatively intact.
Topic Areas: Prosody,