Speech production in individuals with Parkinson's disease: Basic kinematic parameters and effects of increased linguistic demands on interarticulatory coordination

Bridget M Walsh, Purdue University

Abstract

The central aim of this experiment was to provide an integrative description of basic kinematic parameters of speech movements and to determine the effects of increased linguistic demands on coordination of interarticulator trajectories in individuals with Parkinson’s disease (PD). It has long been recognized that people with PD suffer from dysarthria resulting from lesions of the basal ganglia complex. Earlier studies of speech production in PD using perceptual, acoustic, or kinematic analyses have yielded mixed findings regarding the characteristics of articulatory movements underlying the speech disorder, in some cases reporting reduced articulatory output and in other instances revealing normal orofacial movement parameters for speech. Recent investigations of cognitive and language processes in individuals with PD implicate basal ganglia involvement in non-motor communicative behaviors as well. These more recent findings have produced new hypotheses of how the subcortical basal ganglia form neural networks with cortical structures to mediate aspects of cognition, language, as well as speech motor control. Given these new models of basal ganglia functions, it seems reasonable to hypothesize that speech movement planning and execution in these patients may be affected by the demands placed on the production system. Earlier studies of the speech of PD patients involved very simple syllable, single word, or nonword utterances. Therefore, we manipulated the length and complexity of a set of sentences to be produced. Recordings of lip and jaw movements and acoustic data were collected in 16 individuals with PD and 16 age- and sex-matched neurologically healthy adults. On repeated productions individuals with PD had more variable speech movement trajectories and smaller articulatory displacements and lower velocities compared to the control participants. For all participants, increased utterance length and linguistic complexity were associated with increased speech movement variability, but there was no evidence that individuals with PD were especially affected by increased linguistic demands. Acoustic analyses confirmed that the individuals with PD spoke with reduced intensities and had reduced second formant (F2) slopes. This experiment provides a more cohesive picture of how speech production is affected by the disease processes of PD and helps to clarify the role of the basal ganglia in speech and language processes.

Degree

Ph.D.

Advisors

Smith, Purdue University.

Subject Area

Communication|Speech therapy

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