1. Brain-Computer Interfaces
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2. Brain computer interface
Basic Idea
Generic BCI system
Types of BCI system
EEG technique
Applications
Advantages
Disadvantages
BCI Innovators
Future developments
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3. MAN AND THE WORLD Man interacts with the world using his
five senses and limb movements
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4. THOUGHTS faster than ACTIONS
Actions are mechanical movements while thoughts are electrical impulses.
Thoughts are faster than actions
So direct interaction with the world through thoughts would be faster.
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5. Brain Computer Interface
Brain-computer interface (BCI) is a fast-growing emergent technology in which researchers aim to build a direct channel between the human brain and the computer.
BCI- The Ultimate in Human Computer Interfacing
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6. What is it good for? Neurofeedback Brain Computer Interfaces
treating attention deficit hyperactivity disorder (ADHD), poor concentration
Brain Computer Interfaces
People with little muscle control (i.e. not enough control for EMG or gaze tracking)
People with ALS, spinal injuries
High Precision
Low bandwidth (bit rate)
Electromyography (EMG) is an electrodiagnostic medicine technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram.
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord.
Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. The progressive degeneration of the motor neurons in ALS eventually leads to their death. When the motor neurons  die, the ability of the brain to initiate and control muscle movement is lost. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed.

7. Components of BCI Generation of signals from brain Preprocessing,
Feature extraction,
Classification,
Device control.
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8. Generic BCI System
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9. signal extraction techniques
Different neuroimaging methods are used to derive meaningful interpretations from the brain signals which are captured by microelectrodes:
EEG - Electro encephalography
ECoG - Electro cortico graphy
MEG - Magneto encephalo graphy
BOLD - Blood-Oxygen-Level-Dependent (signal)
MRI - Magnetic Resonance Imaging
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10. What is an EEG?
An electroencephalogram is a measure of the brain's voltage fluctuations as detected from scalp electrodes.
It is an approximation of the cumulative electrical activity of neurons.

11. EEG Background
Richard Caton discovered electrical properties of exposed cerebral hemispheres of rabbits and monkeys.
German Psychiatrist Hans Berger discovered alpha waves in humans and invented the term “electroencephalogram”
1950s - Walter Grey Walter developed “EEG topography” - mapping electrical activity of the brain.

12. Types of BCI
Invasive- inside grey matter of brain Partially Invasive- inside the skull but outside the grey matter Non Invasive- outside the skull, on the scalp
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13. Invasive BCI S Electrode inserted directly into grey matter
Highest quality signal can obtain
But are prone to scar-tissue build-up
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14. Partially Invasive BCIs
Implanted inside the skull but rest outside the grey matter of the brain
Produce better resolution signals than non-invasive BCIs where the bone tissue of the cranium deflects and deforms signals
Carry lower risk of forming scar-tissue in the brain than fully-invasive BCIs.
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15. Non-Invasive BCIs
low signal quality due to electrodes are not directly interact with neurons
It is safest as no surgery required.
EEG is widely used for this technique
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16. EEG Technique for BCI Electrodes attached to the scalp
Electric signals of the brain are amplified.
Transmitted to the computer
Software converts them into technical control signals ( computer commands)
These computer commands controls the devices.
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17. Physical Mechanisms
EEGs require electrodes attached to the scalp with sticky gel
Require physical connection to the machine
At present perhaps the most cumbersome factor is the need for scalp electrodes, which require an electrolyte gel for electrical conductivity, and as little hair as possible. Users with normal hair have to deal with electrode prep before use and hair cleaning after use.
The scalp electrodes may always be the limiting factor in resolution of a EEG- computer interface. There is probably much electrical activity concomitant with thought patterns and sensory images in the brain, but the fine resolution of this activity is not detectable with surface electrodes.
Another difficulty, is that the EP systems are quite slow. The EP must be derived by signal averaging, that is, multiple repetitions of the evoked response must be accumulated in order to see the EP signal above the noise. In the case of Dr. Sutter's system, 1.5 seconds is required to discriminate the selection of a particular letter from the alphabet array. The continuous EEG interface systems have faster switch functions because the change in alpha or mu wave amplitude can be detected more quickly.

18. Cerebral Cortex
Parietal Lobe - involved in the reception and processing of sensory information from the body. Frontal Lobe - involved with decision-making, problem solving, and planning. Occipital Lobe - involved with vision. Temporal Lobe - involved with memory, emotion, hearing, and language.

19. EEG WAVES There are 5 major types of EEG waves Delta Waves Theta Waves
Alpha Waves
Beta Waves
Gamma Waves
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20. Continuous Brain Waves
Generally grouped by frequency: (amplitudes are about 100µV max)
Type
Frequency
Location
Use
Delta
<4 Hz
everywhere
occur during sleep, coma
Theta
4-7 Hz
temporal and parietal
correlated with emotional stress
(frustration & disappointment)
Alpha
8-12 Hz
occipital and parietal
reduce amplitude with sensory stimulation or mental imagery
Beta
12-36 Hz
parietal and frontal
can increase amplitude during intense mental activity Mu
9-11 Hz
frontal (motor cortex)
diminishes with movement or intention of movement
Lambda
sharp, jagged
occipital
correlated with visual attention
Vertex
higher incidence in patients with epilepsy or encephalopathy
The continuous or resting rhythms of the brain, "brain waves", are categorized by frequency bands. Different brain wave frequencies correspond to behavioral and attentional states of the brain, and a traditional classification system has long been used to characterize these different EEG rhythms:
Alpha waves are between 8 and 13 Hz with amplitude in the range of µV. They appear mainly from the occipital and parietal brain regions and demonstrate reduced amplitude with afferent stimulation, especially light, and also with intentional visual imagery or mental effort.
Beta activity normally occurs in the range of 14 to 30 Hz, and can reach 50 Hz during intense mental activity. Beta arises mainly from the parietal and frontal areas and is associated with the normal alert mental state.
Theta waves occur in the 4 to 7 Hz range and arise from the temporal and parietal regions in children, but also occur in adults in response to emotional stress, especially frustration or disappointment.
Delta activity is inclusive of all brain waves below 3.5 Hz. Delta occurs in deep sleep, during infancy, and in patients with severe organic brain disease
Mu waves, also known the comb or wicket rhythm, appears in bursts at Hz. This activity appears to be associated with the motor cortex and is diminished with movement or the intention to move.
Lambda waves are large electropositive sharp or saw-toothed waves that appear mainly from the occipital region and are associated with visual attention.
Vertex waves are electronegative waves of 100 µV amplitude which appear in normal individuals, especially children, in the absence of overt stimulation. These waves have been observed to have a higher incidence in patients with epilepsy or other encephalopathy.
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21. Electrode Placement Standard “10-20 System” Spaced apart 10-20%
Letter for region
F - Frontal Lobe
T - Temporal Lobe
C - Center
O - Occipital Lobe
Number for exact position
Odd numbers - left
Even numbers - right
The listener wore headphones to hear the music, and a cap with EEG sensors on it to record neural activity. The 26 sensor electrodes were arranged according to the standard for EEG placement. faculty.washington.edu/chudler/1020.html. The sensors are labelled by proximity over a regions of the brain (F=Front, T=Temporal, C=Central, P-Parietal, O=Occipital) followed by either a 'z' for the midline, or a number that increases as it moves further from the midline. Odd numbers (1,3,5) are on the left hemisphere and even numbers (2,4,6) on the right e.g. T4 is on the right temporal lobe, above the right ear. An additional 10 sensors were used to record heart-rate, skin conductance, eye movements, breathing and other data. The sensors were recorded as interleaved channels of signed 32 bit integers at a rate of 500 samples per second. The channels were separated into individually named files and converted to ascii format for simplicity of loading on different systems.
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22. Electrode Placement
A more detailed view:
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23. Alpha and Beta Waves Studied since 1920s
Found in Parietal and Frontal Cortex
Relaxed - Alpha has high amplitude
Excited - Beta has high amplitude
So, Relaxed -> Excited
means Alpha -> Beta
Alpha waves can also be volitionally manipulated. Alpha activity appears with closing the eyes or defocussed attention. Also, alpha is suppressed by light or normal attentive activity. Thus, most people can learn to produce bursts or "epochs" of alpha activity, and then return to normal beta activity. This behavioral "switch" between beta and alpha activity can be used as the mental command for a brain wave controller. When the signal processor detects the alpha epoch by using an FFT to detect the change in the fundamental frequency of the brain rhythm, an instruction is sent to control an output device.

24. Mu Waves Studied since 1930s Found in Motor Cortex
Amplitude suppressed by Physical Movements, or intent to move physically
(Wolpaw, et al 1991) trained subjects to control the mu rhythm by visualizing motor tasks to move a cursor up and down (1D)
The mu wave has been studied since the 1930s and came to be referred to as the "wicket rhythm" since the rounded waves on the EEG record resembled a croquet wicket. In a study in the 1950s, Gian Emilio Chatrian and colleagues showed that the amplitude of this wave could be suppressed by physical movements, and later studies showed that simply the intent to move or certain other efforts requiring visual or mental activity would also suppress the amplitude of the mu wave. In Wolpaw and MacFarlands' lab, subjects can learn to control the amplitude of this waveform by trial and error when visualizing various motor activities, such smiling, chewing, or swallowing. For different subjects, different images enhance or suppress the voltage of the mu waveform. Upon detection of the voltage change in the mu wave, the system sends output code to drive a cursor up or down on a computer screen. Thus, with a certain amount of feedback training, users can learn to move the cursor with the appropriate mental effort. The researchers hope that this system will eventually provide a communications link for profoundly disabled individuals.

25. Mu and Beta Waves
(Wolpaw and McFarland 2004) used a linear combination of Mu and Beta waves to control a 2D cursor.
Weights were learned from the users in real time.
Cursor moved every 50ms (20 Hz)
92% “hit rate” in average 1.9 sec

26. BCI Examples - Prostheses
(Wolpaw and McFarland 2004) allowed a user to move a cursor around a 2 dimensional screen
(Millán, et al. 2004) allowed a user to move a robot around the room.

27. BCI Examples - Music
Lusted and Knapp demonstrated an EEG controlling a music synthesizer in real time.
In 1987, the authors (Lusted and Knapp) demonstrated an EEG controller which was configured to switch settings of a music synthesizer. Music was chosen for the controller's output because sound provided a good demonstration the real-time capabilities of this technology. By wearing a headband that positioned electrodes on the back of the head to detect the occipital alpha activity, users controlled a switch that responded to the transitions between beta and alpha epochs. More recently, composer Atau Tanaka of the Stanford Center for Computer Research in Music and Acoustics uses this EEG controller in his performance pieces to switch certain synthesizer functions while generating sounds using EMG signals.
Another recent application for the EEG-alpha interface is being used as a controller for visual keyboard software. In Brazil, Roberto Santini is using a Biomuse system configured to provide him with the EEG switch, since he is immobilized with advanced ALS (amyotrophic lateral sclerosis) and cannot make use of his eye movements to use the EOG controller. With the EEG controller interfaced to the mouse port of his personal computer, Roberto can select letters from the visual keyboard on the screen. The selection process is somewhat laborious because each choice is binary. The word processing software allows him to zoom in on a given letter by dividing the screen in half. Thus, starting from the full keyboard, as many as 6 steps may be required to move down the branching pattern in order to select a desired letter. Roberto now writes complete letters and is pleased that he can again communicate with others.
Currently, the authors and a few other researchers, notably a group headed by Alkira Hiraiwa at the NTT Laboratories in Japan, are continuing development in EEG controllers by using pattern recognition algorithms in an attempt to detect signature patterns of EEG activity which correspond to volitional behaviors. The eventual aim is to develop a vocabulary of EEG signals that are recognizable by the computer. The process of pattern recognition is similar to that used for EMG gesture recognition. In this case, the "gesture" is a thought pattern or type of visualization. For instance, attempts have been made to train a neural network to recognize subvocalized letters, where subjects think a particular letter as though about to speak it, and over many repetitions, train the neural net to recognize a brain wave pattern that occurs with this behavior. This is a promising technique, but the training period is laborious in order to obtain a high percentage of accuracy in matching letters with brain wave patterns.
As mentioned earlier, another approach to development of an EEG-computer interface involves the use of an evoked potential (EP) paradigm. Evoked potentials are produced by activating a sensory pathway with a particular type of stimulus, such as a flash of light or a noise burst, and then recording a characteristic waveform from the brain at a particular time interval after the stimulus presentation. Since the characteristic evoked waveform appears at a specific time after the stimulus, researchers can discriminate between the EP and the noise because they know its temporal location in the post-stimulus EEG recording. Other electrical activity which occurs before and after the EP latency window can be ignored.
Eric Sutter at the Smith-Kettlewell Institute in San Francisco has developed a visual EP controller system for physically handicapped users. The user can select words or phrases from a matrix of flashing squares on a computer screen. The flashing square upon which the user is fixating his or her gaze produces a characteristic EP from a particular portion of the visual cortex, and since the amplitude of the EP produced from the foveal portion (point of maximal accuity) of the retina is much larger than the response form surrounding retinal areas, the computer can discriminate which word square the user is watching at any given time. Dr. Sutter has implanted electrodes under the scalp to improve the quality of the EEG signal in these patients. Also, this eliminates the need to put on scalp electrodes for each test session since the patients simply "plug in" their transdermal connection to interface with the computer.

28. In Review… Brain Computer Interfaces
Allow those with poor muscle control to communicate and control physical devices
High Precision (can be used reliably)
Requires somewhat invasive sensors
Requires extensive training (poor generalization)
Low bandwidth (today 24 bits/minute, or at most 5 characters/minute)

29. Area of implementation
Medical science
Enabling disabled people
Vision and hearing
Paralysis treatment
Prosthetic devices (legs, hands etc)
Provide a means of communication to completely paralyzed patients
Surgically implanted devices used as replacement
for paralyzed patients
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30. General application Control a robot Playing games
For physically weak persons to handle the computer
Cursor control
Allow those with poor muscle control to
communicate and control physical devices
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31. Example of BCI application
A phsically handicapped man operates a BCI wheelchair
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32. More examples
Japanese student walking in the virtual world with the character controlled by his brain waves.
A single handed man interfaced with BCI
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33. ADVANTAGES
BCIs will help creating a Direct communication between a human or animal brain and computers.
Also it provides better living, more features, more advancement in technologies etc.
High Precision (can be used reliably)
Low bandwidth
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34. Difficulty in Implementation of BCI:
COST require for BCI is very high.
It is RISKy, because it operates with brain.
Effective BCI technique requires invasive method.
Requires magnetically shielded room and special kind of helmet.
It is SLOW
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35. Future Work Improving physical methods for gathering EEGs
Improving generalization
Improving knowledge of how to interpret waves

36. Future developments Better signal detection Shortening training time
Improving learning (neurobiological and psychological basis)
New recording methods (NIRS, ECoG)
Broader range of applications (interface to commercially available assistive devices; treatment of diseases)
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37. Conclusion BCI is highly promising. Provide high standard of living.
Extend our limits.
Impart a new level to the popular quote-
“I think therefore I am!”
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38. Any……???
Thank u…
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