On the receptive prosodic loss in Parkinson's disease

To comprehensively explore how the processing of linguistic and affective prosodic cues is affected by idiopathic Parkinson's disease (PD), a battery of receptive tests was presented to eleven PD patients without intellectual or language impairment and eleven control subjects (NC) matched for age, gender, and educational attainment. Receptive abilities for both low-level (discrimination) and higher-level (identification) prosodic processing were explored; moreover, the identification of prosodic features was tested at both the lexical level (phonemic stress perception) and over the sentential domain (prosodic pattern identification). The results obtained demonstrated a general reduction in the ability of the PD patients to identify the linguistic- and affective-prosodic meaning of utterances relative to NC subjects, without a concurrent loss in the ability to perceive phonemic stress contrasts or discriminate prosodic patterns. However, the qualitative pattern of the PD and NC groups' performance across the various identification conditions tested was remarkably uniform, indicating that only quantitative differences in comprehension abilities may have characterized the two groups. It is hypothesized that the basal ganglia form part of a functional network dedicated to prosodic processing (Blender et al., 1989) and that the processes required to map prosodic features onto their communicative representations at the sentence level are rendered less efficient by the degenerative course of PD.