A presentation method of a traveling image for the sensory feedback for control of the paralyzed upper extremity

Functional electrical stimulation (FES) is applied to restore the holding function of the upper extremity of quadriplegics whose condition is due to spinal chord injury. In that case, the feedback concerning the state of a patient's finger is needed. As a realistic sensory feedback method, the information transmission by surface electrical stimulation to the shoulder of a patient with remaining sensation is considered. Experiments were performed for a normal subject and for quadriplegics, and the psychophysical characteristics were examined. The following observations were made: By using the stimulus with a time-varying intensity pattern, a phantom sensation (PS) moving on the surface between two electrodes is produced; by extending the idea to the case of three channels, PS is produced which moves around over a wide range on the shoulder. Then a discrimination experiment was performed for the range of PS movement, and it is shown that PS can be used as a practical method of sensory feedback.