brain machine interface

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Brain-Machine Interface
Ajay.J, & Ninan Lawrence
Sixth Semester, Electronics and Communication Department
Mohandas College of Engineering and Technology

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Abstract
Brain-Machine Interface (BMI) is a communication system, which enables the user to control special
computer applications by using only his or her thoughts. It will allow human brain to accept and control
a mechanical device as a part of the body. Data can flow from brain to the outside machinery, or to brain
from the outside machinery. Different research groups have examined and used different methods to
achieve this. Almost all of them are based on electroencephalography (EEG) recorded from the scalp.
Our major goal of such research is to create a system that allows patients who have damaged their
sensory/motor nerves severely to activate outside mechanisms by using brain signals.
Cyber kinetics Inc, a leader in neurotechnology has developed the first implantable brain-machine
interface that can reliably interpret brain signals and perhaps read decisions made in the brain to
develop a fast, reliable and unobtrusive connection between the brain of severely disabled person to a
personal computer.

Main Principle
Main principle behind this interface is the
bioelectrical activity of nerves and muscles. It is now
well established that the human body, which is
composed of living tissues, can be considered as a
power station generating multiple electrical signals
with two internal sources, namely muscles and
nerves.
We know that brain is the most important part of
human body. It controls all the emotions and
functions of the human body. The brain is composed
of millions of neurons. These neurons work together
in complex logic and produce thought and signals
that control our bodies. When the neuron fires, or
activates, there is a voltage change across the cell,
(~100mv) which can be read through a variety of
devices. When we want to make a voluntary action,
the command generates from the frontal lobe. Signals
are generated on the surface of the brain. These
electric signals are different in magnitude and
frequency.
By monitoring and analyzing these signals we can
understand the working of brain. When we imagine
ourselves doing something, small signals generate
from different areas of the brain. These signals are
not large enough to travel down the spine and cause
actual movement. These small signals are, however,
measurable. A neuron depolarizes to generate an
impulse; this action causes small changes in the
electric field around the neuron. These changes are
measured as 0 (no impulse) or 1 (impulse generated)
by the electrodes. We can control the brain functions
by artificially producing these signals and sending
them to respective parts. This is through stimulation
of that part of the brain, which is responsible for a
particular function using implanted electrodes.

Subject Detailing
A brain-machine interface (BMI) is an attempt to
mesh our minds with machines. It is a
communication channel from a human's brain to a
computer, which does not resort to the usual human
output pathways as muscles. It is about giving
machine-like capabilities to intelligence, asking the
brain to accommodate synthetic devices, and learning
how to control those devices much the way we
control our arms and legs today. These experiments
lend hope that people with spinal injuries will be able
to someday use their brain to control a prosthetic
limb, or even their own arm. A BMI could, e.g.,
allow a paralyzed patient to convey her/his intentions
to a computer program. But also applications in
which healthy users can benefit from the direct brain
computer communication are conceivable, e.g., to
speed up reaction times. Initially theses interactions
are with peripheral devices, but ultimately it may be
interaction with another brain. The first peripheral
devices were robotic arms. Our approach bases on an
artificial neural network that recognizes and classifies
different brain activation patterns associated with
carefully selected mental tasks. Using BMI artificial
electrical signal can stimulate the brain tissue in order
to transmit some particular sensory information

Electroencephalography(Eeg)
Electroencephalography (EEG) is a method used in
measuring the electrical activity of the brain. The
brain generates rhythmical potentials which originate
in the individual neurons of the brain. These
potentials get summated as millions of cell discharge
synchronously and appear as a surface waveform, the
recording of which is known as the
electroencephalogram.
When a neuron is exposed to a stimulus above a
certain threshold, a nerve impulse, seen as a change
in membrane potential, is generated which spreads in
the cell resulting in the depolarization of the cell.
Shortly afterwards, repolarization occurs.
The EEG signal can be picked up with electrodes
either from scalp or directly from the cerebral cortex.
As the neurons in our brain communicate with each
other by firing electrical impulses, this creates an
electric field which travel though the cortex, the dura,
the skull and the scalp. The EEG is measured from
the surface of the scalp by measuring potential

Conclusion
Cultures may have diverse ethics, but regardless,
individual liberties and human life are always valued
over and above machines. What happens when
humans merge with machines? The question is not
what will the computer be like in the future, but
instead, what will we be like? What kind of people
are we becoming?
BMI’s will have the ability to give people back their
vision and hearing. They will also change the way a
person looks at the world. Someday these devices
might be more common than keyboards. Is someone
with a synthetic eye, less a person than someone
without? Shall we process signals like ultraviolet, X-
rays, or ultrasounds as robots do? These questions
will not be answered in the near future, but at some
time they will have to be answered. What an
interesting day that will be.

References
Websites:
1. betterhumans.com
2. popsci.com
3. ele.uri.edu
4. duke.edu
5. elecdesign.com
6. brainlab.org
7. howstuffworks.com
Books:
1. Handbook Of Biomedical Instrumentation
By R.S.Khandpur