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The impact of basal ganglia dysfunction on phonetic flexibility: a study in Parkinson’s disease
Poster Session E, Friday, October 2, 11:00 am - 1:00 pm, Wangari Maathai
This poster is part of the Sandbox Series.
Virginie Roland1, Mélen Guillaume2,3, Julien Diard2, Anahita Basirat3; 1Service de Métrologie et Sciences du Langage, Institut de Recherche en Sciences et Technologies du Langage, Université de Mons, Mons, Belgium, 2Laboratoire de Psychologie et NeuroCognition, , Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, LPNC, 38000 Grenoble, France, 3Univ. Lille, CNRS, UMR 9193 - SCALab - Sciences Cognitives et Sciences Affectives, F-59000 Lille, France
Successful spoken communication requires continuous adjustment between perceived and produced speech. Speakers modulate speech rate, pitch, and temporal organization in response to auditory input, a capacity referred to here as phonetic flexibility. This capacity relies on the brain network underlying speech production. However, the role of the basal ganglia in phonetic flexibility is not known. Interestingly, prior work on Parkinson’s disease (PD), which is often used as a model of basal ganglia dysfunction, suggests that auditory rhythmic stimuli may enhance movement in people with PD (PwPD). This finding suggests flexibility in the temporal organization of motor control. However, it remains unclear whether similar effects also apply to speech production in PD. This study aims to address this gap. Phonetic flexibility was examined in 20 PwPD and 20 matched healthy controls using a task derived from the MonPaGe-2.1.0-S battery (Laganaro et al., 2021). In each trial, participants listened to an auditory stimulus (i.e., a model speaker), and then produced speech in three production contexts: repetition, imitation, and inhibition. They also completed a reading task serving as an individual baseline. In the three auditory contexts, participants produced three target sentences presented across five acoustic conditions: unmodified baseline condition, duration compressed (x0.75) and expanded (x1.25), F0 lowered (x0.75) and raised (x1.25). Each participant therefore produced 60 utterances. Building on prior work on speech adaptation in PD, we hypothesize that PwPD will exhibit phonetic flexibility in imitation and repetition contexts, similar as controls. By contrast, on the basis of the literature on inhibitory deficits in PD, we hypothesize that PwPD and controls will differ in the inhibition context. All data have already been collected. Two complementary acoustic measures will be extracted. First, speech initiation latency will be used to assess how rapidly participants engage auditory-motor control. Second, speech rhythm will be estimated using perceptual centers (p-centers) to examine the extent to which participants adapt their speech to that of the model speaker. Together, these measures index phonetic flexibility as a function of task demands and interlocutor characteristics. We will test the impact of group and production context on these measures using mixed models. In addition to statistical analyses of the empirical data, we will use a Bayesian information fusion model (Ma et al., 2023) to examine adaptation patterns in speech rhythm between participants and the model speaker across contexts. This modeling framework has successfully explained empirical findings from a similar paradigm in cerebellar ataxia (Späth et al., 2022), showing that individuals with ataxia differ from controls in how they integrate information from their own planned speech and the model speaker’s input (Guillaume et al., under revision). Together, the findings will allow us to determine whether PD affects global initiation processes, speech rhythm, or both. This will provide insight into the role of basal ganglia dysfunction in adaptive speech control with respect to temporal aspects during interactive speech communication.
Topic Areas: Speech Motor Control, Computational Approaches