Muscle co-activity tuning in Parkinsonian hand movement: disease-specific changes at behavioral and cerebral level.

We investigated simple directional hand movements based on different degrees of muscle co-activity, at behavioral and cerebral level in healthy subjects and Parkinson's disease (PD) patients. We compared "singular" movements, dominated by the activity of one agonist muscle, to "composite" movements, requiring conjoint activity of multiple muscles, in a center-out (right hand) step-tracking task. Behavioral parameters were obtained by EMG and kinematic recordings. fMRI was used to investigate differences in underlying brain activations between PD patients (N = 12) and healthy (age-matched) subjects (N = 18). In healthy subjects, composite movements recruited the striatum and cortical areas comprising bilaterally the supplementary motor area and premotor cortex, contralateral medial prefrontal cortex, primary motor cortex, primary visual cortex, and ipsilateral superior parietal cortex. Contrarily, the ipsilateral cerebellum was more involved in singular movements. This striking dichotomy between striatal and cortical recruitment vs. cerebellar involvement was considered to reflect the complementary roles of these areas in motor control, in which the basal ganglia are involved in movement selection and the cerebellum in movement optimization. Compared to healthy subjects, PD patients showed decreased activation of the striatum and cortical areas in composite movement, while performing worse at behavioral level. This implies that PD patients are especially impaired on tasks requiring highly tuned muscle co-activity. Singular movement, on the other hand, was characterized by a combination of increased activation of the ipsilateral parietal cortex and left cerebellum. As singular movement performance was only slightly compromised, we interpret this as a reflection of increased visuospatial processing, possibly as a compensational mechanism.

Development and validation of a user-friendly data logger (SUDALS) for use with flexible electrogoniometers to measure joint movement in clinical trials.

OBJECTIVE: Our aim was to develop and validate a user-friendly data logger system (SUDALS) for use with flexible electrogoniometry. METHODS: Data pertaining to flexion/extension of the knee from 10 normal subjects were collected during a range of activities of daily living (ADL) such as walking, ascending and descending stairs, getting in and out of a chair and deep squatting. The accuracy, reliability and reproducibility of the data from SUDALS were verified by comparing against the data simultaneously collected from the Vicon system. RESULTS: The results of these studies indicate that the SUDALS together with flexible electrogoniometers is able to produce stable, precise, accurate and repeatable knee flexion/extension angles with little variation existing between the data produced by the SUDALS, the Vicon system and that reported in the literature. CONCLUSION: The SUDALS together with flexible electrogoniometers is a useful clinical tool, capable of recording knee flexion/extension angles accurately during ADL.