the principle, motivation , limitations and future of bci ( ppt )
TRANSCRIPT
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BRAIN COMPUTER INTERFACE
The Principle, Motivation , Limitations and
Future of BCI
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INTRODUCTION
A brain-computer interface (BCI) is intended to
enable its user to communicate with a
computer by mere thoughts
The main motivation behind BCI is to enable aperson with severe physical disability to
control devices by their thoughts
For a normal human this will be leap fromjoystick to thoughts
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HUMAN BRAIN
The brain controlsall human activitiesin some form or the
other Human brain has a
network of billions ofneurons which make
this controllingpossible
A neuron consists ofseveral dendrites, a
cell body and an
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STRUCTURE OF NEURON
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WORKING OF THE NEURON
Neuron is equivalent to a single binary
processing unit
DendritesInput channel
Axoncarries binary information
If the input exceeds a certain threshold voltage
the neuron is said to be firing
The output is either a 1 or nothing.
Generation of electric field.
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OUTLINE OF BCI
Signal Acquisition
Pre-processing
Feature Extraction
Classification
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SIGNAL ACQUISITION-
ELECTROENCEPHALOGRAPHY
The most commonly used method of signal
acquisition is Electroencephalography or EEG.
Provides continuous recording of the brains
electrical processes
It is a non-invasive technique
Currently in used in clinics for detection of
epileptic seizures
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ELECTROENCEPHALOGRAP
HY
When the neurons
are active, they
produce an
electrical potential. Electrodes -
measurement of
electric potential
Array of electrodes-
more precision
Quantify thoughts
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ELECTROENCEPHALOGRAP
HY
Fig: EEG of a typical human in different
stages
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PRE-PROCESSING AND NOISE
REJECTION
Preprocessing is a step to process raw EEG
signals to re-construct the original brain
activity
It is achieved by:
Referencing
FilteringArtifact subtraction
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FEATURE EXTRACTION
Features arecharacteristics of asignal that are able todistinguish betweendifferent emotions
The method used forfeature extraction isShort-time Fouriertransform
Feature extractionrequirements Reduce the size of the
data
Minimum redundancy
Preserve all information
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CLASSIFICATION
After Feature Extraction we have data, but
we still have to identify the thought
In classification we decode this data and
equate different signal patterns with different
human emotions
Now the output of classifier is given to an
external device according to the application
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APPLICATIONS
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BCI FOR DISABLED
How is a physically disabled person different
from a normal person?
Normal personBody reacts according to the
signals from the brain. Disabled personA particular part of the body is
dead. Hence it cant react to the brain signals. But
the brain is working.
A mobile mind in an immobile body
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PROSTHETIC ARMS AND
LEGS
Brain signals are detected
by the EEG and are
externally given as input
to the prosthetic arms andlegs
The damaged part is
bypassed in this process
The prosthetic partsrespond to the stimulus
from the brain and
perform the desired action
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SENSORY INPUT
Cochlear implant is a common application of
BCI, which is helpful for people with hearing
disability
Sound Waves ---> Several organs in the ear ---> Auditory Nerves
Damaged organs cause hearing disability
In BCI, brain signals are directly given to theauditory nerves which makes a deaf person
listen to sound
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SMART DEVICES
BCI analyses the brain signal of the person
and gives real-time feedback, thus helping the
person train his brain to reduce anxiety,
improve concentration and be relaxed Devices can adjust themselves according to
the users mood and make the machine-
human interaction smoother and smarter
Gaming will become a lot more intuitive
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LIMITATIONS
Timing issues- Speed of the brain is much
greater than the processing speed of
computers
Voltage from each neuron is small and cannotbe detected. Hence we cannot really read
thoughts or understand the words we are
thinking
Interference- External source of noise might
interfere and give inaccurate readings
Need of a very diverse panel of expertise
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COMMERCIAL PRODUCTS
Mind Wave
Developed by Neurosky.
Measures brain waves and
use them to controldevices
The MindWave won the
Guinness Book of World
Records award forHeaviest machine moved
using a brain control
interface
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COMMERCIAL PRODUCTS
Muse
Developed by IntraXon
Four sensor headband
Measures the brain wavesin run time
Can be used to play
games
Made for every day use
Currently on display at
CES 2013
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CONCLUSION
With advancement in our understanding of the
brain and various other engineering disciplines
likes signal processing, etc, the technology of
brain computer interface is bound to benefit Not only is it a fascinating technology for every
human, but also an absolute necessity to a
severely disabled person
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Y U