BrainGate Technology
BrainGate Technology
BrainGate Technology
Thousands of people around the world suffer from paralysis, rendering them dependent
on others to perform even the most basic tasks. But that could change, thanks to the
latest achievements in the field of BrainGate technology, which could help them regain
a portion of their lost independence. The mind-to-movement system that allows a
quadriplegic man to control a computer using only his thoughts is a scientific milestone.
Braingate neural interface system is based on, Cyber kinetics platform technology to
sense, transmit, analyze and apply the language of neurons. Scientists are to implant
tiny computer chips in the brains of paralyzed patients which could ‘read their
thoughts’. It would be a huge therapeutic application for people who have seizures,
which leads to the idea of a ‘pacemaker for the brain’.
Introduction to BrainGate
When a person becomes paralyzed, the neural signal from the brain no longer
reaches their designated site of termination. However, the brain continues to
send out these signals although they do not reach their destination. It is these
signals that the brain gate system picks up and they must be present in order for
the system to work. It is found that people with long-standing, severe paralysis
can generate signals in the area of the brain responsible for voluntary movement
and these signals can be detected, recorded, routed out of the brain to a
computer and converted into actions enabling a paralyzed patient to perform
basic tasks. Scientists are to implant tiny computer chips in the brains of
paralyzed patients which could ‘read their thoughts’.
Brain gate consists of a surgically implanted sensor that records the activity of
dozens of brain cells simultaneously. The system also decodes these signals in
real time to control a computer or other external devices. The brain gate
technology platform was designed to take advantage of the fact that many
patients with motor impairment have an intact brain that can produce
movement commands allowing the brain gate system to create an output signal
directly from the brain, bypassing the route through the nerves to the muscles
that cannot be used in paralyzed people.
1. The chip: A four-millimeter square silicon chip studded with about 100
hair-thin microelectrodes is embedded in the primary motor cortex, the
region of the brain responsible for controlling movement.
2. The connector: When the person thinks of moving the computer cursor,
electrodes on the silicon chip implanted into the person’s brain detect
neural activity. His cortical neurons fire in a distinctive pattern, the signal
is transmitted through the pedestal plug attached to the skull.
3. The converter: The signal travels to an amplifier where it is converted to
optical data and bounced by fiber optic cable to a computer.
4. 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.
A silicon chip implanted in the brain cortex through pedestal
When the person thinks of moving the computer cursor, electrodes on the
silicon chip implanted into the person’s brain detect neural activity from an
array of neural impulses in the brains motor cortex. The impulses transfer from
the chip to a pedestal protruding from the scalp through connection wires. The
pedestal filters out unwanted signals or noise and then transfers the signal to an
amplifier. The signal is captured by acquisition system and is sent through a
fiber optic cable to a computer. The computer then translates the signal into an
action, causing the cursor to move.
The braingate system is a neuromotor prosthetic device consisting of an array of
one hundred silicon microelectrodes; each electrode is 1mm long and thinner
than a human hair. The electrodes are arranged less than half a millimeter apart
in the array, which is attached to a 13cm-long cable ribbon cable connecting it to
a computer.
Our brains are filled with neurons, individual nerve cells connected to one
another by dendrites and axons. Every time we think, move, feel or remember
something, our neurons are at work. That work is carried out by small electric
signals that zip from neuron to neuron as fast as 250 mph. The signals are
generated by differences in electric potential carried by ions on the membrane
of each neuron.
Although, the paths, signals take are insulated by something called myelin, some
of the electric signal escapes. Scientists can detect those signals, interpret what
they mean and use them to direct a device of some kind. It can also work the
other way around. For example, researchers could figure out what signals are
sent to the brain by the optic nerve when someone sees the color red. They
could rig a camera that would send those exact signals into someone’s brain
whenever the camera saw red, allowing a blind person to “see” without eyes.
Basic working principle of the BrainGate
Pic credits: HowStuffWorks
Basically, there are two methods to sense the signals sent by the neurons:
1. ECoG: Invasive method
2. EEG: Non invasive method
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 duramater. ECoG is a very promising intermediate BCI
(Brain computer interface) modality because it has 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 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
1. BrainGate can remain safely implanted in the brain for at least two years.
2. Later it can safely be removed as well.
3. Spiking from many neurons the language of the brain can be recorded,
routed outside the human brain and decoded into command signals.
4. Paralyzed humans can directly and successfully control external devices,
such as a computer cursor using these neural command signals.
5. 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).
Potential Applications
Reading brain signals is not an easy task as even a simple movement, such as
raising a hand, requires electrical signals from many regions of the brain.
Implanted electrodes pick up just a tiny fraction of the signals from neurons that
fire. It is difficult for the computer to convert these signals resulting in the
cursor jiggling and making it difficult to select icons on the screen with
accuracy.
1. Size: Brain gate right now has a bulky look with cables and processors.
The device has to be less bulky to make the technology mainstream.
Cyber kinetics is developing a prototype of a device that would fit behind
the ear of the patient, much like the cochlear implant, and connect via a
magnet to the computer equipment, thus eliminating the need to cross
the skin. This will lead to a wireless Brain Gate, giving the patient greater
freedom.
2. Calibration: In its current form, it is essential to recalibrate the device
before each use by the patient. The team is working on automated
calibration to allow greater independence to the user.
3. Muscle connection: Today, a direct connection from the computer to a
muscle is not possible. But researchers believe that they will be able to
achieve coordinated muscle movement. In theory, electrodes and wires
could connect muscles to the functioning brain, thus bypassing the
damaged spinal cord.
4. The brain is incredibly complex. To say that all thoughts or actions are the
result of simple electric signals in the brain is a gross understatement.
There are about 100 billion neurons in a human brain. Each neuron is
constantly sending and receiving signals through a complex web of
connections. There are chemical processes involved as well, which EEGs
can’t pick up on.
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.