Prosthetic control via BCI enables a person to operate a robotic arm, hand, or other prosthetic device using decoded neural signals rather than residual muscle activity. This capability is particularly important for people with high spinal cord injuries (tetraplegia) or advanced ALS, who have insufficient residual muscle control for conventional myoelectric prosthetics.
Milestone Demonstrations
- 2012 (Hochberg et al.): Cathy Hutchinson, paralyzed for 15 years, used a Utah Array BCI to control a robotic arm to grasp a bottle of coffee and bring it to her mouth — the first self-directed reach-and-grasp with an implanted BCI.
- 2016 (Ajiboye et al.): Bill Kochevar used a BCI combined with functional electrical stimulation (FES) of his own arm muscles to feed himself — the first demonstration of BCI-controlled volitional arm movement using the patient's own limb.
- 2017 (Collinger et al.): Jan Scheuermann used a Utah Array BCI to control a 7-degree-of-freedom robotic arm (DEKA LUKE arm) with enough dexterity to perform activities of daily living.
Degrees of Freedom
The challenge of prosthetic control scales with the number of degrees of freedom (DOF) the user must control simultaneously:
- 2 DOF: Cursor control (x, y velocity)
- 3 DOF: Cursor + click, or 3D endpoint control
- 7 DOF: Full robotic arm (3 translation, 3 rotation, 1 grasp)
- 10+ DOF: Individual finger control for dexterous manipulation
Current intracortical BCIs can control 3-7 DOF simultaneously. Individual finger control from cortical recordings has been demonstrated in research settings but not yet in clinical BCI systems.
Sensory Feedback
A critical limitation of current prosthetic control BCIs is the lack of tactile and proprioceptive feedback. Users must rely on vision to monitor the prosthetic, which is slow, cognitively demanding, and insufficient for tasks requiring force regulation. Bidirectional BCIs that combine motor decoding with somatosensory stimulation are the solution, and early clinical demonstrations show significant improvement in prosthetic control when sensory feedback is provided.
Toward Clinical Viability
For BCI-controlled prosthetics to become clinically viable, several requirements must be met: reliable long-term implants (years to decades), wireless operation (no percutaneous connectors), sufficient DOF for practical tasks, sensory feedback, and minimal daily calibration. Current systems meet some but not all of these requirements.