Neuroprosthetics (also spelled neuroprosthetics) refers to devices that interface with the nervous system to replace, restore, or augment lost neural function. These devices can restore movement, sensation, hearing, vision, and cognitive function in patients with neurological disorders or injuries. The field combines neuroscience, biomedical engineering, and clinical medicine to create electronic interfaces that communicate with neural tissue.
- Recording devices: Electrodes capture neural activity (ECoG, intracortical arrays)
- Stimulation devices: Deliver electrical/current to modulate neural activity (DBS, cochlear implants)
- Bidirectional systems: Combine recording and stimulation for closed-loop control
- Signal acquisition: Amplification and filtering of neural signals
- Feature extraction: Spike sorting, frequency analysis
- Decoding algorithms: Machine learning for movement intention prediction
- Encoding algorithms: Tactile feedback, visual/auditory sensation
| Device | Application | Development Stage |
|--------|-------------|-------------------|
| Brain-Computer Interface (BCI) | Cursor/robotic control | Clinical trials |
| Functional Electrical Stimulation (FES) | Muscle activation | FDA-approved |
| Exoskeletons | Gait assistance | Clinical use |
| Cortical prosthetics | Upper limb control | Clinical trials |
| Device | Application | Status |
|--------|-------------|--------|
| Cochlear implants | Hearing restoration | FDA-approved (>50,000 implants) |
| Retinal implants (Argus II) | Vision restoration | FDA-approved |
| Vestibular implants | Balance restoration | Experimental |
| Tactile feedback systems | Touch sensation | Clinical trials |
| Device |
Target |
Stage |
| Memory prosthetics |
Hippocampal encoding |
Experimental |
| Deep brain stimulation |
Movement, mood |
FDA-approved |
| Responsive neurostimulation |
Epilepsy |
FDA-approved |
| Vagus nerve stimulation |
Multiple indications |
FDA-approved |
¶ Paralysis and Spinal Cord Injury
- BCI-controlled robotics: Tetraplegic patients control robotic arms with thought
- Functional electrical stimulation: Surface or implanted systems activate muscles
- Exoskeletons: Powered orthoses enable standing and walking
- Communication devices: Speech synthesis from neural signals
¶ Parkinson's Disease and Movement Disorders
- Deep brain stimulation (DBS): Approved for PD, essential tremor, dystonia
- Targets: Subthalamic nucleus (STN), globus pallidus internus (GPi)
- Outcomes: 50-70% improvement in motor symptoms; reduced medication needs
- Responsive neurostimulation (RNS System): Detects and stops seizures
- Vagus nerve stimulation (VNS): Reduces seizure frequency
- Closed-loop systems: Real-time seizure detection and intervention
- BCI-based rehabilitation: Motor imagery with FES
- Cortical stimulation: Enhance plasticity during rehabilitation
- Robotic therapy: Repetitive movement training
- Parkinson's Disease (1997): Tremor, rigidity, bradykinesia
- Essential Tremor (2003): Medication-refractory tremor
- Dystonia (2003): Primary and secondary dystonia
- Epilepsy (2013): Lennox-Gastaut syndrome
- Obsessive-Compulsive Disorder (2009): Treatment-refractory OCD
- Implanted pulse generator: Battery-powered stimulator
- Lead electrodes: Stereotactic placement in target region
- Extension wire: Connects lead to generator
- External controller: Patient and physician programming
- Frequency: 130-185 Hz typical for PD
- Pulse width: 60-210 μs
- Amplitude: 1-5 V or 0-10 mA
- Contact configuration: Monopolar or bipolar
| Technology |
Spatial Resolution |
Invasiveness |
| EEG |
Poor (~1 cm) |
Non-invasive |
| ECoG |
Good (~1 mm) |
Subdural |
| Intracortical |
Excellent (~100 μm) |
Invasive |
| Trial |
Device |
Application |
Status |
| NCT04685464 |
BCI for arm control |
Tetraplegia |
Recruiting |
| NCT05358114 |
Visual prosthesis |
Blindness |
Phase 1 |
| NCT04802109 |
Memory BCI |
Memory impairment |
Phase 1 |
- Nathan Coppin: Tetraplegic controls robotic arm with 9 DOF
- BrainGate trials: Cursor control and text entry
- Synchron Stentrode: Endovascular electrode array
- External microphone captures sound
- Speech processor extracts spectral information
- Transmitter sends signals to implanted electrode array
- Electrical stimulation of auditory nerve
- Brain interprets signals as sound
- Speech perception: 80%+ open-set speech recognition in optimal candidates
- Music perception: Variable; challenging but improving
- Bilateral implants: Standard of care for bilateral severe hearing loss
- Components: External camera, video processing unit, retinal electrode array
- Resolution: 60 electrodes
- Visual outcomes: Light perception, motion detection, some letter recognition
- PRIMA: Subretinal photovoltaic implant (clinical trials)
- Alpha-AMS: Second-generation retinal prosthesis
¶ Challenges and Future Directions
- Longevity: Electrode degradation over time
- Signal stability: Foreign body response affects recording quality
- Power delivery: Battery life and charging
- Miniaturization: Device size reduction
- Biocompatibility: Tissue response to implanted materials
- Infection risk: Surgical implantation complications
- Neural plasticity: Adapting to artificial input/output
- Neural dust: Millimeter-scale wireless sensors
- Optical interfaces: Two-photon microscopy for neural recording
- Gene therapy combined: Optogenetic prosthetics
- Closed-loop systems: Real-time adaptive stimulation