Jan Scheurmann was paralysed from neck down more than a decade ago due to degenerative brain disease. But thanks to the brain-computer interface (BCI), now she could grab and eat a chocolate with her robotic arm and even hi-five her doctors! With two aspirin-sized electrodes implanted to her brain and a few months of training, she was able to successfully manipulate a mindcontrolled robot arm with seven axes of movement (front-back, up-down, left-right, wrist yaw, wrist pitch, wrist roll and hand grasp). After grabbing her first bite of chocolate she declared, “One small nibble for a woman, one giant bite for BCI.”
“This is a spectacular leap towards greater function and independence for people who are unable to move their own arms,” the senior investigator of the University of Pittsburgh’s Pitt School of Medicine, Andrew Schwartz, said in a release. “This technology, which interprets brain signals to guide a robot arm, has enormous potential that we are continuing to explore. Our study has shown us that it is technically feasible to restore ability; the participants have told us that BCI gives them hope for the future.”
“This is a spectacular leap towards greater function and independence for people who are unable to move their own arms,” the senior investigator of the University of Pittsburgh’s Pitt School of Medicine, Andrew Schwartz, said in a release. “This technology, which interprets brain signals to guide a robot arm, has enormous potential that we are continuing to explore. Our study has shown us that it is technically feasible to restore ability; the participants have told us that BCI gives them hope for the future.”
In an earlier independent study by the BrainGate Implant, another paralysed woman, Cathy Hutchinson, was
able to use the arm to pick up a thermos of coffee and drink it from a straw.
What is BCI
BCI, also known as a brain–machine interface (BMI), mind-machine interface (MMI) or direct neural interface, is a method by which the brain signals are used to control an external device. In simple terms, this technology helps you to control machines with thoughts. BCI has become one of the important areas of research in medical field as it can restore and augment human sensory, motor and cognitive functions.
The BCI System
A long-term goal of the BCI projects is to develop a neurotechnology that could convert thoughts into actions, thereby helping people with limb loss or paralysis to restore their movement and control, making them independent to a great extent.
The current BCI system comprises three main segments:
Sensor. A device implanted in the brain, usually multi-electrode arrays (MEAs), that records signals directly
related to imagined limb movement.
Decoder. A set of computers and specialised programs that can interpret the neural signals collected by the sensor, and which turn them to corresponding commands for an external device.
External device. A communication device like computer or a robotic limb on which the decoded brain signals are converted to required actions.
How It Works
The first step is to associate raw neuronal signals with their corresponding movements. The magnetic resonance imaging mapping is used to find out the regions of the brain that are active when performing certain functions. This helps to place the electrode in the right target.
The sensors are smaller than a square centimetre and are implanted in the primary cortex of the brain. Each of these MEAs has around hundred contact points that record the response of individual neurons as well as populations of neurons.
The microchips are first implanted in brain. The patient is made to think about doing something, like moving the hand forward or rolling the wrist. Each activity triggers a unique set of neurons. When a neuron is excited, a potential difference is developed between the inside and outside of the cell membrane and an ion current is developed. This ion current is converted into electron current by the sensors and sent to the decoder.
The difficult task is to interpret and associate the brain signals to their respective movements. With the help of revised filtering, processing and complex computer programs, and after many trials, the signals related to each activity can be figured out. The specially designed embedded softwareis programmed so as to receive each signal and make the connected external device (like a prosthetic hand) physically perform the activity associated with that particular signal.
Commercial Viability
Though extensive researches are going on in this field, only a very small number of products are available in the consumer market; even lesser belonging to medical industry. High cost of production and unavailability of participants for clinical trials are a few reasons for their reduced popularity.
Some of the medical devices based on neurotechnology are discussed in brief below:
BrainGate implant. It is a brain implant developed by Cyberkinetics and is one of the most important BCI
systems.
Deep brain stimulator. It is manufactured by Medtronic and is used to treat Parkinson’s and dystonia. It is also researched for treatment of epilepsy and depression.
Hearing aid. The medical device company Otologics has made this product available in Europe.
Bionic eye. An artificial retina by Second Sight Medical Products, going through the first phase of trial.
Vagus nerve stimulator. It is used for treating epilepsy, depression and obesity. Cyberonics, MetaCure and
EnteroMedics are the major manufacturers.
Powered exoskeleton. A robotic exoskeleton that can help the elderly and the disabled to walk and lift objects, developed by Cyberdyne.
Implanted defibrillator. This device is meant for people who have problems with irregular heartbeat. It prevents sudden cardiac arrest. It is developed by Medtronic, St. Jude Medical, Boston Scientific, Sorin Group CRM and Biotronic.
Ventricular assist. It helps the heart chamber pump blood. Thoratec, Abiomed, Inc. and World Health Corporation manufacture this product.
Breathing pacemaker. It helps people with spinal cord injury to help them breathe on their own by pacing diaphragm. The device is produced by Synapse Biomedical, Inc.
PillCam. A capsule with miniature camera that can be swallowed and is used for endoscopy. Given Imaging is the manufacturer of this capsule.
Dr*g delivery to spine. This dr*g delivery system is meant for patients with chronic pain. It is produced by Medtronic and MicroCHIPS.
Artificial arm. Prosthetic arms with 18 degrees of freedom, developed by DEKA Research and Development Corporation.
Bionic hand. This product designed by Touch Bionics can perform more hand functions than a normal prosthetic hand.
Sacral nerve stimulation. Developed by Medtronic to control some bladder functions.
Smart leg. Most advanced lower limb prosthetic by Otto Bock Healthcare.
Robotic foot. It has many added features over prosthetic foot. Ossur is the manufacturer of this product.
What Future Holds
As the next step of this technological advancement, researchers are planning to introduce feedback potentials to the electrodes, which can result in the interpretation of sensations like grip strength. They are also working on miniaturisation of equipment and introduction of wireless technology. It may even be possible to avoid the robotic devices by directly bypassing the appropriate signals to the corresponding motor nerves in the damaged section of the spinal cord. This means the paralysed patient will be able to move his/her own body.
The field of BMI has made a considerable development in the past decade. Though only few products are available in the market, extensive research and lab works are going on in this field. What was once just an interesting science fiction theme is now growing very close to reality. Neurotechnology has developed from just a figment of imagination to monkeys moving cursors on computer screen to humans controlling prosthetic
limbs in three-dimensional space with dexterity. In coming years, we can expect BCI to not only restore human functions but also augment it and improve the quality of living.
