Psychophysiological responses to robot training in different recovery phases after stroke

Psychophysiological responses have become a valuable tool in human-robot interaction since they provide an objective estimate of the user's psychological state. Unfortunately, their usefulness in rehabilitation robotics is uncertain since they are influenced by both physical activity and pathological conditions such as stroke. We performed psychophysiological measurements in subacute and chronic stroke patients as well as healthy controls during a reaching and grasping exercise task performed in a multimodal virtual environment. Furthermore, we evaluated the differences in kinematic and static parameters between the three groups of subjects. The results of the observed kinematic and static evaluation parameters showed significant differences when different assistive modes enabled the subject to focus on a particular function of the exercise, like reaching or grasping, or coordinated actions that combine reaching and grasping, reflecting the motor abilities of the individual. The analysis of psychophysiological responses suggests that both chronic and subacute stroke subjects have weaker psychophysiological responses than healthy subjects, though the responses of chronic patients have recovered somewhat. This certainly indicates that further studies are needed before psychophysiological responses can be used in clinical practice.