A debilitating feature of Parkinson's disease (PD) is slow movement (bradykinesia). Empirical examination of bradykinetic limbs has shown increased movement time as the primary kinematic feature. Putative aberrations in movement velocity control may underlie this clinical sign. Bradykinesia has often been implicated in explanations of PD dysarthria. However, this sign and its underlying neuropathology have not been studied in the orofacial system to warrant such causal links. The proposed research investigates the kinematic features and pathophysiology of bradykinesia in PD orofacial and limb motor systems relative to normal limb speed regulation paradigms. These research objectives will be achieved through a series of hypothesis- directed experiments on PD and normal subjects using highly refined displacement and electromyographic transduction techniques during lip, tongue, and jaw speech/non-speech and index finger movements. Parallel observations across normal and abnormal orofacial and limb systems will quantitatively define bradykinesia as well as enhance interpretations and provide critical perspectives on nervous system processes underlying velocity regulation. Twenty idiopathic PD adults and twenty normal age- and sex-matched adults will serve as subjects over the two project years. The PC-controlled experimental protocols will provide a facile presentation of visually highlighted target and position feedback displays. Data acquisition and analyses will be accomplished via a SUN microsystem laboratory computer using customized software. This research pilots a unique experimental approach which simulates a functional movement pattern common to the lips, jaw, and tongue during speech and vegetative behaviors and to the index finger during prehensile action. It is also a necessary first step in understanding orofacial speech/non-speech and limb bradykinesia and abnormal velocity regulation. Such determinations are not only pivotal in diagnosing and in ensuring appropriately focused treatment programs for PD dysarthria but also in providing hypotheses for subsequent studies of normal and abnormal movement control in the orofacial and limb motor systems. Finally, this project will facilitate the transition of the Principal Investigator from a clinical position to one with research opportunities in speech movement control.
