Learning motor synergies by persons with Down syndrome.

Persons with Down syndrome are frequently described as 'clumsy'. The recent progress in the development of quantitative approaches to motor synergies has allowed researchers to move towards an understanding of 'clumsiness' at the level of underlying control mechanisms. This progress has also offered an opportunity to quantify changes in motor synergies that accompany improvement in the performance of motor tasks. Previous studies of our group have shown, in particular, that persons both with and without Down syndrome are able to show improvements in indices of their multi-finger synergies in tasks that require accurate production of finger forces. In particular, 3 days of practice has been shown to lead to significant improvements in indices of multi-finger synergies that stabilize the time patterns of the total force produced by the fingers of a hand. Persons with Down syndrome showed a qualitative change in their synergies that failed to stabilize the total force altogether prior to practice and became able to do so after practice. In addition, the studies have also shown that variable practice is more beneficial for the improvement of motor synergies than blocked practice. I would like to draw an optimistic conclusion that persons with Down syndrome are not inherently 'clumsy', but have a vast potential for an improvement of their motor performance. The current state of the area of motor control allows researchers and practitioners to tap into these reserves, and to use quantitative indices of changes in motor synergies with practice to optimize motor performance of these individuals.