According to new research presented at SfN Neuroscience (3–7 November, San Diego, CA, USA), advances in connecting neural stimulation to physical control of the body are transforming the development of prosthetics and therapeutic training for people with disabilities.
As our understanding of neural functions and interactions combines with technical advances, scientists are developing new and improved prosthetics and therapies that aim to improve quality of life for people with conditions such as paralysis, stroke and blindness.
Electrical signals that stimulate specific regions in the brain or body can bypass injuries in the spinal column or eyes and activate target regions, training the brain to process movement or vision in the most effective manner possible.
Hand–grasp neuroprosthetics for spinal cord injury patients achieve new precision
One study presented at the conference highlights advances in the precision and force of brain-controlled, computer-guided hand movements, and anticipate that they may enable people with quadriplegia and others with hand paralysis to begin integrating electrical-stimulation-based prosthetics into their daily life.
This research demonstrates significant progress in allowing a paralyzed person to progress from thinking about what needs to be done to actually reanimating his or her own hand. The researchers developed an electronic bypass system, called NeuroLife®, that uses a chip implanted into the motor cortex to record brain activity, sophisticated machine-learning algorithms to decode and translate thoughts into action commands, and a wearable electrical stimulation sleeve that drives the muscles to move.
This new system enabled a 27-year-old male paralyzed from a spinal cord injury to select one of seven possible hand-movement options, and to manipulate objects of different sizes, shapes and weights with skilled, forceful grasps. The decoded signals of intent were used to control activation of the participant’s forearm muscles. The participant’s functional improvements were evaluated using the Grasp and Release Test, which is a standardized hand-performance assessment. The team also made significant strides towards clinic-to-home translation of the technology by making the system portable and using algorithms that minimize training and improve reaction time.
“In this study, we demonstrate seven skilled hand functions, a critical step in making hand–grasp neuroprosthetics dexterous enough to function in everyday life. These advances significantly improve the state of the art for assistive devices that restore hand function in individuals with paralysis and establish a path towards moving these devices out of the research lab and into patients’ home,” concluded Gaurav Sharma (Battelle Memorial Institute, OH, USA).
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Avatar and functional electrical stimulation-aided training improves motor rehabilitation for stroke patients
A second study has reported using avatars to provide visual feedback in combination with real-time, electronic feedback in the body to improve the use of motor function in stroke patients.
The new stroke therapy is called recoveriX and pairs mental imagination of moving arms or legs with visual presentation of the imagined movements. For example, when a person with stroke imagines a hand movement while seeing the same hand movement visualized through an avatar while simultaneously receiving muscle stimulation in that hand, then these individuals regain the ability to grasp more successfully and quickly than those who received only the electrical stimulation.
The therapy was also reported to reduce spasticity and tremors, as well as increased the scores on a key measure for daily living activities.
Christoph Guger (g.tec Neurotechnology GmbH, Schiedlberg, Austria), commented: “Our study demonstrates that adding visual stimulation to stroke therapy helps the brain relearn how to move disabled arms and legs, making rehabilitation more successful than physical therapy alone. Physicians typically tell stroke patients that there will be no functionality improvements after 1 year, but we have had numerous patients show improvements many years after their stroke.”
Prosthetic hand system helps amputee ‘feel’ what device is doing
A new prosthetic hand system is the first prosthesis designed for regular home use to restore task-related sensations to an amputee, according to a new study presented at SfN Neuroscience.
This study demonstrates a bidirectional system called the Neural Enabled Prosthetic Hand System, which was approved by the US FDA in 2016 for investigational use. The system uses fully implantable components to provide task-related sensations to an amputee by stimulating small groups of sensory fibers in peripheral nerves. Designed to be suitable for everyday use in real-world environments, the system utilizes muscle activity to drive motors to open and close the prosthetic hand, while signals from the sensory embedded in the prosthetic are used to convey information to the user about the degree of hand opening and grasp force.
The first and only person to-date who has received the surgical implant has been fitted with the external components, has undergone laboratory-based experiments and fitting procedures, and is now using the system on a daily basis at home.
This study is the first demonstration that prosthetic systems with implanted electronics work outside the lab in everyday use. “The long-term viability of implanted, wirelessly enabled peripheral nerve stimulation technology could form the foundation for a wide range of applications in bioelectronics medicine, including applications to treat metabolic or digestive diseases, improve mental health or immune system function, or alleviate chronic pain,” concluded Ranu Jung (Florida International University, FL, USA).
Chethan Pandarinath (Emory University, GA, USA), who was the press conference moderator, concluded: “The advances presented today help expand what’s possible with brain–machine interfaces. The neuroscience advances and range of techniques presented provide potential new assistive devices for people with disabilities, and also open the door to a deeper understanding of how our brains translate intention into actions.”
- Sharma G, Colachis S, Bockbrader MA et al. Advancing hand–grasp neuroprosthetics for spinal cord injury patients: the next step toward clinic-to-home translation. Programs and Abstracts of SfN Neuroscience 2018. San Diego, CA, USA, 3–7 November 2018 (Abstract 5407).
- Edlinger G, Cao F, Dimov S, Guger C. A brain–computer interface group study for motor rehabilitation of chronic stroke patients. Programs and Abstracts of SfN Neuroscience 2018. San Diego, CA, USA, 3–7 November 2018 (Abstract 2944).
- Jung R, Kuntaegowdanahalli SS, Thota AK et al. Neural-enabled prosthetic hand system to restore sensation in upper-limb amputees. Programs and Abstracts of SfN Neuroscience 2018. San Diego, CA, USA, 3–7 November 2018 (Abstract 12764).