Abstract des Autors

The purpose of this study was to evaluate, using the vibration technique, the extent to which children rely on propriomuscular inputs to control their goal-directed movements on-line. Children aged 5, 7, 9, 11 years and adults performed pointing movements by sliding a stylus towards targets without any visual feedback while vibration (30 Hz and 70 Hz) was being applied to the distal tendon of their biceps muscie. The results show that in all the subjects the 70 Hz vibration induced a deviation of the limb trajectory in the adduction direction (towards the contralateral side of the body), which was maximum at 5 years of age, decreased between 5 and 7, and levelled out later on. The 30 Hz frequency did not affect the trajectory except in the 5-year-olds. Neither the duration of the pointing movements nor the trajectory parameters were affected by any of the vibration conditions. The effects of target distance on the movement time were found to decrease after 9 years of age, as did the number of velocity peaks and the relative time to peak, whereas the peak velocity increased after 1 1 years of age. In conclusion, in all the age-groups studied, the additional propriomuscular messages were interpreted like an error signal in controlling the movement trajectory in the absence of visual feedback, particularly in the younger children, whereas the older children and adults seem to have relied more on a feedforward process. Verf.-Referat