Early stage Parkinson’s disease (PD) shares certain symptoms with essential tremor (ET), which makes it difficult to differentiate between the two. We analyzed cyclical body bends to find kinematic parameters that are capable of differentiating among PD, ET and normal control (NC) subjects. A linear discriminant analysis of the joint angles showed a reliable distinction between NC and the two groups of patients, while differentiating reasonably well between PD and ET. PD patients showed difficulty performing hip segment rotation around the vertical axis, whereas ET patients demonstrated enlarged torso sway in the frontal plane. These findings suggest that kinematic parameters of body movement in the standing position are sensitive enough to serve as subclinical marks in the early diagnosis of PD and ET.
Marina Kurgansky, Alexander Frolov, Marat Ioffe, Alexey Karabanov and Ludmila Chernikova
Elena V. Biryukova, Blandine Bril, Alexander A. Frolov and Mikhail A. Koulikov
What are the differences between the movements of an expert exhibiting superior performance compared with those of a novice or even an experienced person? Adopting a functional approach to tool use, this study presents results from experimental field research on stone knapping from Indian craftsmen of different levels of skill. The results showed that the differences in the levels of motor skill appeared in movement variability rather than in particular kinematic content. The higher is the level of motor skill, the more kinematic solutions are used, the more stable are the functional and the more variable the nonfunctional joint loadings. This study strongly suggests that to really understand learning processes and motor expertise, naturalistic challenging activities that require years of practice need to be elicited.