5. Problem Statement
• Traumatic lesions of the central nervous
system as well as neurodegenerative
disorders continue to inflict devastating,
and so far irreparable, motor deficits in
large numbers of patients
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6. • 300,000 Americans are spinal cord
injured.
• 52% of spinal cord injured individuals are
considered Partial paralysis and 47% Total
Paralysis
• Approximately 15,000 new injuries occur
each year.
• 82% are male.
• 56% of injuries occur between the ages of
16 and 30
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7. Objective
• Help handicaps to live independently
without the need of others assistance
• Providing a method to help handicaps to
adapt with ubiquitous environments.
• Cover new grounds of the applications of
EEG signals.
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9. Brain
• The human brain is the center of the
human nervous system and is a highly
complex organ.
• The brain monitors and regulates the
body's actions and reactions.
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10. Each Hemisphere
into four "lobes“
• Frontal lobe.
• Parietal lobe.
• Occipital lobe.
• Temporal lobe.
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11. Motor Cortex
• The motor cortex is located in the rear
portion of the frontal lobe
• The motor cortex is divided into two main
areas, Area 4 and Area 6.
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12. THE CEREBELLUM
• In a healthy person, the cerebellum first
receives information about the intended
movement from the sensory and motor
cortexes.
• Then it sends information back to the
motor cortex about the required direction,
force, and duration of this movement
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15. Brain Signals &
Electroencephalogram (EEG)
• EEG is a recording of the electrical activity
of the brain directly from the scalp
produced by the firing of neurons within
the brain.
• No EEG signal pattern is duplicated for
any two distinct actions
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16. How EEG Works ?
• Recorded by placing small metal discs
called electrodes on the scalp in certain
positions
• Each electrode is labeled with a letter and
a number to indicate its position.
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18. How the Signal is Produced
• EEG machines use
differential amplifiers to
produce each channel or
trace of activity.
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19. • The EEG signal itself is in the waveform so
it is required that an analogue to digital
signal converter be employed to produce
the signal as a series of numeric values
each representing voltage values of each
channel at a certain time instance.
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20. The actions that affect the EEG
signals
1. Muscular movements
2. Expressive states
3. Cognitive States
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21. Muscular Movement
• This is defined as any physical movements
• this is because in order to move any
muscle the brain performs certain actions
to send orders to this muscle to move
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23. Expressive States
• This refers to maintaining a specific
emotional state
• This is much more difficult to measure
than any muscular movement as its
contribution in the overall brain activity is
less.
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25. Cognitive States
• A cognitive state means a person’s state
of mind, it is generally said to mean a
person’s thoughts.
• Surely since a thought is generated from
the brain than it is expected that it would
affect the brain activity and thus be
reflected in the EEG signal.
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27. Difficulties in Detection of EEG
Signals
• The EEG signal is contaminated with eye
blinks and involuntary movements that are
reflected in the signal and have to be
removed.
• The signal is contaminated with DC drifts
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29. Brain-Computer Interface
• A brain–computer interface (BCI) is a
direct communication pathway between a
brain and an external device computer
interface (BCI).
• It’s also known as direct neural interface
or a brain–machine interface.
• BCIs are often aimed at assisting,
augmenting or repairing human cognitive
or sensory-motor functions.
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30. Brain-Computer Interface (Cont)
• The field of (BCI) has since advanced
mostly toward neuroprosthetics
applications that aim at restoring damaged
hearing, sight and movement.
• Thanks to the remarkable cortical plasticity
of the brain, signals from implanted
prostheses can, after adaptation, be
handled by the brain like natural sensor or
effector channels.
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33. EMOTIV Headset (Cont)
• EMOTIV Headset is a brain-computer
interface (BCI) based on EEG.
• EMOTIV Headset will make it possible for
games and applications to be controlled
and influenced by the player's mind, and
facial expressions.
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34. EMOTIV Headset (Cont)
• The EMOTIV Headset (EPOC) has 14
electrodes (compared to the 19 electrodes
of a standard medical EEG).
• It also has a two-axis gyro for measuring
head rotation.
• The headset must first be trained to
recognize what kind of thought pattern
equates to a certain action.
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35. EMOTIV Headset (Cont)
• It can measure four categories of inputs:
1. Conscious thoughts
2. Emotions
3. Facial expressions
4. Head rotation
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To carry out goal-directed movements, your motor cortex must first receive various kinds of information from the various lobes of the brain: information about the body's position in space, from the parietal lobe; about the goal to be attained and an appropriate strategy for attaining it from the anterior portion of the frontal lobe; about memories of past strategies, from the temporal lobe.
People Suffering from Mis functioanllity in the Cerebellum their body would have great effect on the body’s balance
Due to the required direction and force duration aren’t measured in the right way
n the human brain, planning for any given movement is done mainly in the forward portion of the frontal lobe.
This part of the cortex receives information about the individual's current position from several other parts. Then, like the ship's captain, it issues its commands, to Area 6.
Area 6 acts like the ship's lieutenants. It decides which set of muscles to contract to achieve the required movement, then issues the corresponding orders to the "rowers"—the primary motor cortex, also known as Area 4. This area in turn activates specific muscles or groups of muscles via the motor neurons in the spinal cord.
In clinical contexts the EEG is the measurement of the brain’s spontaneous electrical activity over a short period of time usually from 20-40 minutes. The waveforms recorded are thought to reflect the activity of the surface of the brain, the cortex. This activity is influenced by the electrical activity from the brain structures underneath the cortex.
So basically EEG signals are electrical signals uniquely produced by the brain when performing certain actions. No EEG signal pattern is duplicated for any two distinct actions. For example moving your right arm can produce a certain EEG pattern and moving your left arm will produce a totally different and independent EEG pattern.
There are several placement techniques but the most standard one is called the 10/20 system –it’s called so because the electrodes are placed at positions separated by 10 to 20 per cent of the size of the whole head.
F-> Frontal Lobe
T-> Temporal Lobe
C-> Central Lobe
O-> Occipital Lobe
Even Number for Right
Odd Number for Left
Each amplifier has two inputs, An electrode is connected at each one.
These amplifiers measure the voltage difference between the two signals of it’s inputs and the resulting signal is amplified and then displayed as a single channel of the EEG activity
this activity is input along with another one to amplifiers that measure the potential difference between them and amplifies it to produces a single channel, so each EEG signal channel is the measuerment of the difference of the activities produced by two different parts of the brain.
As you can see this EEG activity(associated with blinking) is very vivid and appears easily in the EEG pattern, it can be viewed by the naked eye as the response from the brain is very high and produces high amplitudes in the signal that are easily visible
being happy, sad, excited, tired or confused…..
it’s very difficult to believe that having certain feelings reflect to the brain activity but this shows that anything in the human being is connected to the brain
Of course as you can see it isn’t visible in the EEG signal since it’s contribution to the signal is small so the amplitude of the signal associated with a mental cognitive state is very small and nearly not visible by the naked eye, but we know it’s there.
The DC value is defined as the average value of the EEG signal, a DC drift is the change of the DC value of an EEG signal over time, and this is affected by electrode polarization where this causes extra voltage difference between the electrodes that is measured along with the EEG signal.
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Estimating a specific cognitive state is one of the problems solved by pattern recognition. Since it’s previously mentioned that each brain activity is associated with a specific unique EEG pattern then there would be no problem to determine a cognitive state by recognizing its pattern.
Neuroplasticity (also referred to as brain plasticity, cortical plasticity or cortical re-mapping) is the changing of neurons, the organization of their networks, and their function via new experiences
