Neurally-Interfaced Hand Prosthesis Restores Motor Control Function in Brain

A research team has presented a report on adaptive plastic changes in an amputee’s brain after implantation of multielectrode arrays within peripheral nerves. The results have been published in the Restorative Neurology and Neuroscience’s current issue.

Four microelectrode arrays were implanted in the ulnar and median nerves of a 26-year old male with a left arm amputation. He received this implantation in his stump for four weeks. Before implantation, two weeks of video training was offered to the patient, through which he was taught three specific movements that can be carried out using his phantom hand. Under this experimental period, the patient experienced rigorous training, wherein hand prosthesis was controlled by employing the implanted microelectrodes for achieving the same hand grip tasks. Visual feedback from the prosthesis as well as sensory feedback from the demonstrator was given to the patient. Upon each movement, the nerves received electrical pulses. While the patient moved the prosthesis and his right hand, EEG signals were recorded.

The patient’s right hand movement indicated perceptible activation of the primary sensory and motor areas on the left side of the brain, responsible for right hand movement. Before implantation, the primary motor and sensory areas on the brain’s left side and the pre-motor and supplementary motor cortices on the right and left side of brain were activated by commands to set the phantom left hand in motion. However, the right side of the brain failed to show primary motor cortex movement.

An obvious change in cerebral activation was noted in four weeks following prosthesis motor control training using implanted microelectrodes. Cortical recruitment was found to work symmetrically with right hand movements. Intra-fascicular electrodes enabled generation of new signals passing via peripheral nerves and moving to the cortex, creating an exchange of sensori-motor afferent and efferent inputs and outputs. Four weeks of training contributed to achieving a new functional recruitment of sensorimotor areas dedicated to hand control.

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