Braingate: The Brain-Machine Interface
A brain implant system built and designed to help disabled people who have lost control of their limbs or other bodily functions
What is BRAINGATE?
The Brain Gate Neural Interface Device is a proprietary brain-computer interface that consists of an internal neural signal sensor and external processors that convert neural signals into an output signal under the user's own control. The Brain Gate Neural Interface System is an investigational assistive device designed by Cyberkinetics, Inc. Brain Gate, the technology includes an electrode array The computer chip, which is implanted into the brain, monitors brain activity in the patient and converts the intention of the user into computer commands.
The main concept behind this technology is the idea of implanting tissue microelectrodes known as cortical neural prosthetics (CNPs) into specific portions of the brain to permit the recording of electrical signals sent from both the surface of the brain and within the cerebral cortex region. The motor cortex is chosen as the location to implant the device because it produces the cleanest movement signal. There are thousands of different portions of the brain that control how we function and move. These signals are then translated into command signals that drive a biomedical device, such as a prosthetic limb or computer display. By implanting the CNP into the motor cortex section, nearly smooth movements can be obtained. Every CNP is composed of three building blocks without these the CNPs would not work effectively.
Working Mechanism
BrainGate consists of a sensor implanted in the brain and an external decoder device, which connects to some kind of prosthetic or another external object. The sensor is in the form of a microelectrode array, formerly known as the Utah Array, which consists of 100 hair-thin electrodes that sense the electromagnetic signature of neurons firing in specific areas of the brain, for example, the area that controls arm movement. The sensor translates that activity into electrically charged signals, which are then sent to an external device and decoded in software. The decoder connects to and can use the brain signals to control an external device, such as a robotic arm, a computer cursor, or even a wheelchair. In essence, BrainGate allows a person to manipulate objects in the world using only the mind. In addition to real-time analysis of neuron patterns to relay movement, the BrainGate array is also capable of recording electrical data for later analysis. A potential use of this feature would be for a neurologist to study seizure patterns in a patient with epilepsy.
BrainGate was originally developed by researchers in the Department of Neuroscience at Brown University in conjunction with biotech company Cyberkinetics, Inc. Cyberkinetics later spun off the device manufacturing to Blackrock Microsystems, who now manufactures the sensors and the data acquisition hardware. The BrainGate Company purchased the intellectual property and related technology from Cyberkinetics and continues to own the intellectual property related to BrainGate.
The Brain Gate Neural Interface System is an investigational device. It is not approved for sale and is available only through a clinical study. The sensor consists of a tiny chip smaller than baby aspirin, with one hundred electrode sensors each thinner than a hair that detect brain cell electrical activity. A man with paralysis of all four limbs could directly control objects around him — open a simulated email, play a game of Pong, adjust the volume on the television set — using only his thoughts.
These pilot clinical trial findings, featured on the cover of Nature, mark a major advance in neuroscience, one that offers hope to people with severe motor impairments.
Parts Of Brain Gate
The Chip
A 4-millimeter square silicon chip studded with 100 hair-thin microelectrodes is embedded in Nagle’s primary motor cortex — the region of the brain responsible for controlling movement.
The Connector
When Nagle thinks “move cursor up and left” (toward email icon), his cortical neurons fire in a distinctive pattern; the signal is transmitted through the pedestal plug attached to his skull.
The Converter
The signal travels to a shoebox-sized amplifier mounted on Nagle’s wheelchair, where it’s converted to optical data and bounced by fiber-optic cable to a computer.
The Computer
Brain Gate learns to associate patterns of brain activity with particular imagined movements — up, down, left, right — and to connect those movements to a cursor.
The two methods to sense the signals sent by the neurons :
ECoG — Electrocorticography:
This measures the electrical activity of the brain taken from beneath the skull. Here the electrodes are embedded in a thin plastic pad that is placed above the cortex, beneath the dura mater. ECoG is a very promising intermediate BCI (Brain-computer interface) modality because it has a higher spatial resolution, better signal-to-noise ratio, wider frequency range, and lesser training requirements than scalp-recorded Electroencephalography (EEG), and at the same time has lower technical difficulty, lower clinical risk, and probably superior long-term stability than intracortical single-neuron recording. This feature profile and recent evidence of the high level of control with minimal training requirements shows potential for real-world application for people with motor disabilities. To get a higher-resolution signal, scientists can implant electrodes directly into the gray matter of the brain itself, or on the surface of the brain, beneath the skull. This allows for a much more direct reception of electric signals and allows electrode placement in the specific area of the brain where the appropriate signals are generated. This approach has many problems, however. It requires invasive surgery to implant the electrodes, and devices left in the brain long-term tend to cause the formation of scar tissue in the gray matter. This scar tissue ultimately blocks signals.
EEG — Electroencephalography:
The easiest and least invasive method is a set of electrodes. A device known as an electroencephalograph is attached to the scalp. The electrodes can read brain signals. However, the skull blocks a lot of the electrical signal, and it distorts what does get through.
It is the most studied potential non-invasive interface, mainly due to its fine temporal resolution, ease of use, portability and low set-up cost. A substantial barrier to using EEG as a brain-computer interface is the extensive training required before users can work the technology. Signals recorded in this way have been used to power muscle implants and restore partial movement in an experimental volunteer. They are easy to wear, non-invasive implants produce poor signal resolution because the skull dampens signals, dispersing and blurring the electromagnetic waves created by the neurons. Although the waves can still be detected it is more difficult to determine the area of the brain that created them or the actions of individual neurons.
Advantages of BrainGate
- BrainGate can remain safely implanted in the brain for at least two years.
- Later it can safely be removed as well.
- Spiking from many neurons the language of the brain can be recorded, routed outside the human brain and decoded into command signals.
- Paralyzed humans can directly and successfully control external devices, such as a computer cursor using these neural command signals.
- The speed, accuracy, and precision are comparable to a non-disabled person there is no training necessary (just the ability to think of an action).
Applications
They believe the Brain Gate sensor, which involves implanting electrodes in the brain, could offer new hope to people paralyzed by injuries or illnesses.
It will now be possible for a patient with spinal cord injury to produce brain signals that relay the intention of moving the paralyzed limbs, as signals to an implanted sensor, which is then output as electronic impulses. These impulses enable the user to operate mechanical devices with the help of a computer cursor.
Computer interface approaches include its potential to interface with a computer without weeks or months of training; its potential to be used in an interactive environment, where the user’s ability to operate the device is not affected by their speech, eye movements or ambient noise; and the ability to provide significantly more usefulness and utility than other approaches by connecting directly to the part of the brain that controls hand movement and gestures.
Conclusion:
The technology driving this breakthrough in the Brain-Machine-Interface field has a myriad of potential applications, including the development of human augmentation for military and commercial purposes The primary goal of this technology and devices like brain gate is to help those are who are paralyzed to perform routine activities that are part of normal human existence. The brain gate can be used to replace the memory center in patients affected by strokes, epilepsy or Alzheimers disease.
The ‘BrainGate’ device can provide paralyzed or motor-impaired patients a mode of communication through the translation of thought into direct computer control. Normal humans may also be able to utilize BrainGate technology to enhance their relationship with the digital world provided they are willing to receive the implant.
