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Communication Dans Un Congrès Année : 1999

Effects of L-dopa treatment on the production and perception of intonation by parkinsionians

Résumé

In this study, we tested the perception and the production of intonation by parkinsonian patients with and without pharmacological treatment. Whereas no significant differences were found in the perception tasks, in production, pitch and tonal extent are significantly reduced by Parkinson’s disease and improved by L-dopa treatment. Parkinson's disease (PD) is commonly characterized by a reduction of motor activity and, at the speech production level, by a dysprosody. This trouble is traditionally interpreted as a merely neuro-motor disorder (Darkins et al., Brain Lang., 34, 315-327,1988) affecting the variations of fundamental frequency (F0). The F0 of PD patients is conventionally associated with a global increase in pitch and reduction in range likely due to a greater stiffness and a hypokinesia of the muscles controlling the tension of the vocal folds (Gentil et al., Rev. Neurol., 151, 105-112, 1995). The aim of this study is to precise the origin of the dysprosody of idiopathic PD patients by examining their production and perception of intonation. If this dysprosody is actually a neuro-motor disorder and not a more cognitive alteration of the intonative information processing (Scott et al., J. Neurol. Neurusrg. Psychiatry, 47, 840-843, 1984), we hypothesize that only the production and not the perception of intonation should be affected by PD and improved by L-dopa treatment. We studied a group of ten male PD patients without hearing disorders (mean age: 57.4, (8.9); mean disease duration: 10.9 (4.2); MMS > 25), tested in two clinical conditions: without and with L-dopa treatment. It was compared with a group of six control male subjects (mean age: 61, (6.7)). The perception test consisted in a discrimination task opposing intonative patterns (declarative vs. interrogative), and two tasks of detection and localization of emphatic accents. The production of intonation was evaluated by extracting the F0 from the acoustic signal over the entire reading of a text. We can highlight the tonal and dynamic properties of the frequency distribution by measuring the average pitch, tonal range, limits and dynamic variation of F0 of the global, low, central and high tonal registers for each group of subjects. The results of the perception test show no main statistically significant difference between the PD patients without treatment (OFF), with treatment (ON) and the control subjects (CS), even if the order in term of percentage of good answers for each task is always OFF < ON < CS. In accordance to previous studies, the tonal range and F0 dynamic variation of OFF PD patients are significantly reduced in comparison with normal speakers; but their lower average pitch (OFF < CS) contradicts the results of those studies. Beyond this main effect of PD on intonation, L-dopa treatment significantly increases all tonal factors for at least 50% of the PD patients: OFF < ON. Fairly no significant differences appear between the production of intonation of the PD patients with treatment and the control speakers. These results globally confirm the relative efficiency of dopaminergic treatments on dysprosody of PD patients and the hypothesis of a motor disorder of the parkinsonian dysprosody. Nevertheless, whereas the traditional studies show that the PD patients have a higher F0, our data show opposite results. To account for this phenomenon, we can hypothesize two explanations: i) a muscular stiffness or weakness preventing important and fast tensions of the vocal folds, ii) a reduced subglottal pressure responsible for the decreased intensity and in consequence for the lower pitch. (This work has been supported by a PHRC grant 1997) (Published in Parkinsonism and Related Disorders 5, S1: 121)
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hal-01599106 , version 1 (01-10-2017)

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Yohann Meynadier, Benoît Lagrue, Pierre Mignard, François Viallet. Effects of L-dopa treatment on the production and perception of intonation by parkinsionians. 13th International Congress on Parkinson's Disease, 1999, Vancouver, Canada. pp.121, ⟨10.13140/RG.2.1.1302.9200⟩. ⟨hal-01599106⟩
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