brain computer interface.doc

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Group A

Theme of paper: Advances in Biomedical/instrumentation

Topic of paper: Braingate

Registration id : 324

Name : Ms.Snehal S. Mahajan

Contact no : 9595138231

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CONTENTS

• Abstract

•

Introduction

Brain Computer Interface

What Is Braingate?

• Main principle

• How Braingate works?

• The Braingate chip

• Advantages

• Disadvantages

• Future Expansion

• Conclusion

• References

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ABSRACT

Braingate was developed by the bio-

tech company Cyberkinetics in 2003 in

conjunction with the Department of

Neuroscience at Brown University. The

device was designed to help those who

have lost control of their limbs, or other

bodily functions. 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. Currently the

chip uses 100 hair-thin electrodes that

hear neurons firing in specific areas of

the brain. For example, the area that

controls arm movement. The activity is

translated into electrically charged

signals and is then sent and decoded

using a program, thus moving the arm.

According to the Cyberkinetics'

website, two patients have been

implanted with the Braingate system.

INTRODUCTION

The Braingate technology is the

application of brain computer

interface technology. The brain-

computer interface is the origin for

Braingate technology. Before goinginto the details of Braingate system,

let us first see brain computer

interface technology in brief:

BRAIN COMPUTER

INTERFACE:

BCI uses brain activity to command,

control, actuate and communicate with

the world directly through brain

integration with peripheral devices and

systems. A brain –computer interface

(BCI), some times called a direct neural

interface and is a direct communication

pathway between a human or animal

brain (and brain cell culture) and an

external device.

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In one way BCIs,, computer either

accept commands from the brain or

send signals to it(for example, to restore

vision)but not both.

Two-way BCIs would allow brains

and external devices to exchange

information in both directions, but have

yet to be successfully implanted in

animals or humans.

In this definition, the word brain

means the brain or nervous system of an

organile life form rather than the mind.

computer means any processing or

computational devices, from simple

circuits to silicon chips.

WHAT IS BRAINGATE?

Braingate converts brain activity in

to computer commands. A sensor is

implanted on the brain, and electrodes

are hooked up to wires that travel to a

pedestal on the scalp. From there, a

fiber optic cable carries that brain

activity data to a near by computer.

The brain is “hardwired” with

connections, which are made by billions

of neurons that make electricity when

ever they are simulated. The electrical

patterns are called brain waves. Neurons

act like the wires and gates in a

computer.

Brain controls motor function.

Motor neurons carry a signal from the

central nervous system to the muscles,

skin and glands of the body, while

sensory neurons carry signals from

those outer parts of the body to the

central nervous system.

A technique called

neurofeedback uses connecting sensors

on the scalp to translate brain waves in

to information a person can learn from.

This enables the person learning the

gradual adaptation of motor commands

which takes place after the execution of

one or more movements.The sensors register different

frequencies of the signals produced in

the brain.These changes in the brain

wave patterns indicate whether someone

is concentrating or suppressing his

impulses, or whether he is relaxed or

tense.

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Fig(a):The overall Braingate

system

MAIN PRINCIPLE

The system has a small chip that

will be implanted in the human brain.

This chip can analyse brain signals. The

main principle behind this system is that

with intact brain function, brain signals

are functioning normal and can be

generated even though they are not sent

to the arms and legs.

This means that these signals can be

‘read’ through this chip and translated

into functions that a computer can

understand. For example a cursor

movement. Using this system a person

can move a cursor on a computer screen

by his thoughts, the same way

somebody uses a mouse.

Fig(b):patient implanted with

Braingate chip

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HOW BRAINGATE WORKS?

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 billions 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.

Muscles in the body’s limbs containembedded sensors called muscle

spindles that measure the length and

speed of the muscles as they stretch and

contract as you move other sensors in

the skin respond to stretching and

pressure. The electrodes do the same

work as muscle spindles do. Even if

paralysis or disease damages the part of

the brain that process movement, the

brain still makes neural signals. They

are just not being sent to the arms,

hands and legs. 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. These Signals are generated

on the surface of the brain. These

electric signals are different in

magnitude and frequency. Bymonitoring and analyzing these signals

we can understand the working of brain.

Now the question arises how the signal

analysis is done to implement the exact

task set by the thoughts? This is done by

classifiers. We know that the brainwave

consists of different frequency contents.

These frequency contents are grouped

into different groups. Each group

corresponds to different medical tasks.

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The classifiers are used to classify these

groups to perform corresponding mental

tasks.

BRAINGATE CHIP

The four-millimeter square chip is

placed on the surface of the motor

cortex area of the brain which detect

neural electrical activity. The sensor is

then connected to a computer via a

small wire attached to a pedestal

mounted on the skull. The brainwaves

are recorded with electrodes, which are

placed on the scalp. Electrodes are

small plates, which conduct electricity.

They provide the electrical contact

between the skin and the brainwave

recording apparatus by transforming the

ionic current on the skin to the electrical

current in the wires. To improve the

stability of the signal, the outer layer of

the skin called stratum corneum should

be at least partly removed under the

electrode. Electrolyte gel is applied

between the electrode and the skin inorder to provide good electrical contact.

Currently the chip uses 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 activity is translated

into electrically charged signals and is

then sent and decoded using a program,

which can move either a robotic arm or

a computer cursor. According to the

Cyberkinetics’ website, two patients

have been implanted with the Brain

Gate system. The chip is shown in the

fig(c).

There are a few major problems that

must be addressed when developing

neural implants. These must be made

out of biocompatible material or

insulated with biocompatible material

that the body won’t reject and isolate.One option among the biocompatible

materials is Teflon coating that protects

the implant from the body.

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Fig(c):The Brain chip

Fig (d):Basic elements of the

chip

For working the Braingate chip

requires some basic elements.

Neurochips use amplifiers to boost low-

voltage biological signals, analog-to-

digital converters (ADCs) to digitize

these signals, microcomputers to

process the signals, onboard memory to

store the signals, digital-to-analog

converters (DACs) to stimulate nerves,

and software to control the overall

experiment.

Figure (d) shows a brain chip’s

basic elements. The key requirements

are that the brain chip be small and

lightweight enough to fit inside or onto

the animal, have adequate signal fidelity

for interacting with the mill volt-levelsignals characteristic of nerve tissue,

and have sufficient processing power to

perform experiments of real scientific

value.

ADVANTAGES

The Braingate system is based

on cyber kinetics platform

technology to sense, transmit

analyze and apply the language

of neurons.

The Brain Gate Neural Interface

System is being designed to one

day allow the interface with a

computer and / or even faster

than, what is possible with the

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hands of a person. The Brain

Gate System may offer

substantial improvement over

existing technologies.

The brain gate 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. Brain gate

is currently recruiting patients

with a range of neuromuscular

and neurodegenerative

conditions for pilot clinical trials

in United States.

It provides better and

independent living to those who

have lost control of their limbs

or other bodily functions.

Braingate system enables the

patient to employ a personal

computer as the gateway to a

range of self-directed activities.

These activities may extend

beyond typical computer

functions (e.g., communication)

to include the control of objects

in the environment such as a

telephone, a television and

lights.

Fig:patient availing

braingate system

DISADVANTAGE

Connecting to the nervous

system could lead to permanent

brain damage, resulting in the

loss of feelings or movement, or

continual pain.

Virus attacks may occur to brain

causing ill effects.

The U.S. Food and Drug

Administration (FDA) has not

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approved the Brain Gate Non

Interface System for general use.

This investigate can only be

used in pre-marketing clinical

trials approved by the FDA.

Although many are able to

control the computer with these

systems, such techniques remain

dependent on the muscular

functions and require extensive

training.

FUTURE EXPANSION

Cyber kinetics is developing product

for robotic control, such as a thought-

controlled wheel chair.

In the future, the Brain Gate System

could be used by those individuals who

are in severe condition. Next generation

products may be able to provide an

individual with the control of the device

that allows breathing, bladder and

bowel movements.Also this technology

will become wireless in near future.

CONCLUSION

If we consider a paralysed person as

‘not normal’, the Braingate system can

make this paralysed person normal

again. So from that perspective

Braingate is necessary. It is like the

Braingate can’t work without a human

brain and the human brain (from

someone who is paralysed) can’t

function without the Braingate system.

The goal of this development would be

able to allow these individuals to one

day use their own arms and hands

movement. These developments are

currently at the research stage and are

not available with the existing Brain

Gate System. BCI’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. To put in a nutshell,

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this technology really means “putting

thoughts into action”.

REFERENCES

http:/www.cyberkineticsinc.com

http:/www.fda.gov/cdrh/devadvi

ce/ide/index.shtml

http:/www.usatoday.com/news/h

ealth/2004-10-10-braingate-

cover_x.htm

http:/www.cnn.com/2004/TECH

/10/20/explorers.braingate/

http://www.brown.edu/Administ

ration/News_Bureau/2004-

05/04-035.html

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brain computer interface.doc