Subjects will undergo comprehensive neurophysiological and psychological examinations before, during and immediately after undergoing the sensory feedback intervention.
Direct peripheral nerve sensory feedback.
Multiple transverse, intrafascicular electrodes will be implanted in the median or ulnar nerves of volunteer amputee subjects. Electrical stimulation will be delivered through the active sites by the multi-channel, miniaturized electrical stimulator placed outside the body. To deliver the electrical stimulation sequences and also obtain quantitative and qualitative measures on the effect of the micro stimulation, a semi-automatic and computerized platform is used (psychophysical testing platform). Some patients will undergo a series of testing where he/she will have to perform functional tasks with the hand prosthesis while simultaneously perceiving meaningful sensory feedback. The TIME electrodes will be surgically removed after completion of the study
Non-invasive sensory feedback
Either mechanical stimuli will be applied (in a closed-loop system connecting silicone pads on the prosthetic hand with corresponding pads on the residual limb), or electrical stimulation will be applied through of-the-shelf electrodes. Two steps will be performed as described above; 1) use of a psychophysical testing platform to deliver stimuli and obtain the patients response, 2) following a period with receiving non-invasive sensory feedback, the patient will be asked to perform a series of functional tasks including a hand prosthesis while simultaneously receiving sensory feedback.