Dynamic position sense during a cyclical drawing movement: effects of application and withdrawal of tendon vibration

The present study addressed the stability of dynamic position sense across time as well as the resetting of position sense following its disturbance by means of tendon vibration. Blindfolded subjects drew circles within a specific location of the workspace for a duration of 28 s and at a repetition rate of 1 s(-1). To study the stability of dynamic position sense, the changes in circle drawing performance across time were studied (control condition). Resetting of dynamic position sense was studied by application and subsequent withdrawal of biceps tendon vibration during movement (vibration condition). The results showed that the spatial characteristics of circle drawing in the control condition did not change significantly over the course of the 28 s trial, suggesting that dynamic position sense does not drift systematically across time. Whereas vibration leads to a decrease in diameter, a deterioration of the circularity of the pattern, and a drift of the hand movement toward the body, a restoration of these features was obtained during withdrawal of vibration. This suggests that subjects are able to reset dynamic position sense to reasonable values without the help of vision during active cyclical movement.