Post-stroke training of a pick and place activity in a virtual environment

Picking up and moving small objects is one of the impaired functions stroke survivors most desire to recover. Indeed, this action is involved in many activities of daily living and is often difficult for stroke patients who have problems in (i) grasping the object, (ii) lifting the hand, and (iii) producing a straight trajectory. We have developed a ldquopick & placerdquo exercise using motivational feedback to promote recovery of these functions. This exercise consists of moving an object within a virtual environment where different parameters can be modified to increase the level of difficulty, e.g. a virtual obstacle can be placed in the middle of the workspace which forces the subject to lift the hand in order to reach a target position. The virtual environment is rendered by a Delta workstation that can accurately measure positions and generate forces. To evaluate the training with the ldquopick & placerdquo exercise, three post-stroke subjects practiced twice a week during eight weeks with the setup. The results show a significant decrease in time required to perform the task for the three subjects, while the movements become straighter with training.