1. EEG
DR. JAMES M. ALO, RN,MAN,MAP, PHD

2. Agenda
• Introduction.
• History.
• Neural Activities.
• Action Potentials.
• EEG Generation.
• Brain Rhythms.
• EEG Recording and Measurement.
• Conditioning the Signals.
• Abnormal EEG Patterns.
• Ageing.
• Mental Disorders.
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3. Agenda
• Introduction.
• History.
• Neural Activities.
• Action Potentials.
• EEG Generation.
• Brain Rhythms.
• EEG Recording and Measurement.
• Conditioning the Signals.
• Abnormal EEG Patterns.
• Ageing.
• Mental Disorders.
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4. Introduction
• The human brain activity start between 4-5
months before parental development.
• The human brain represent the brain
functional side to side the status of the
whole body.
• EEG signals measured from the brain of a
human.
• The medium defines the path from
neurons, as so called signal sources to
electro nodes which are the sensors.
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5. Note :-
studying neural functions and
neurophysicological properties of the brain
together with the mechanisms underlying
the generation of the signals for detection,
diagnosis and treatment of brain disorders
and the related diseases.
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6. Agenda
• Introduction.
• History.
• Neural Activities.
• Action Potentials.
• EEG Generation.
• Brain Rhythms.
• EEG Recording and Measurement.
• Conditioning the Signals.
• Abnormal EEG Patterns.
• Ageing.
• Mental Disorders.
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7. History
• Carlo Matteucci (1811–1868) and Emil Du
Bois-Reymond (1818–1896) were the first
people to register the electrical signals
emitted from muscle nerves using a
galvanometer and established the concept
of neurophysiology.
• Analysis of EEG signals started during the
early days of EEG measurement. Berger
assisted by Dietch (1932) applied Fourier
analysis to EEG sequences.
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8. Central Nervous System (CNS) contains of
two types from cells:-
1. Nerve Cell.
2. glia Cell.
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9.  Nerve Cell :-
it consists of
Axons Dendrites Cell Bodies
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11. Nerve cell components
(1) Axons :-
 Is along cylinder.
 Transmits an electrical impulse and
can be several meters long in
vertebrates.
 In animals can be several meters but
in humans the length can be a
percentage of millimeter to a meter .
 An axonal transport system for
delivering proteins to the ends of the
cell exists and the transport system has
‘molecular motors’, which ride upon
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tubulin rails.

12. (2) Dendrites :-
 Are connected to the axons or
dendrites of other cells.
 1 nerve cell connected 10,000 other
nerve cells.
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13. Nerve Nerve Nerve
1 2 3
impulses
dendrites
connects
Dendrites 1 Dendrites Dendrites
2 3
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14. Agenda
• Introduction.
• History.
• Neural Activities.
• Action Potentials.
• EEG Generation.
• Brain Rhythms.
• EEG Recording and Measurement.
• Conditioning the Signals.
• Abnormal EEG Patterns.
• Ageing.
• Mental Disorders.
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15. Neural Activities
A potential of 60–70 mV with negative polarity may be
recorded under the membrane of the cell body.
 This potential changes:-
 If an action potential travels along the fibre,
which ends in an excitatory synapse, an
excitatory postsynaptic potential (EPSP) occurs
in the following neuron.
 If two action potentials travel along the same
fibre over a short distance, there will be a
summation of EPSPs producing an action
potential on the postsynaptic neuron providing a
certain threshold of membrane potential is
reached.
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17. Note
With observation :-
EEG + DC potentials = Abnormalities in the
brain.
DC component:- long strings of zeros or ones.
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18. Agenda
• Introduction.
• History.
• Neural Activities.
• Action Potentials.
• EEG Generation.
• Brain Rhythms.
• EEG Recording and Measurement.
• Conditioning the Signals.
• Abnormal EEG Patterns.
• Ageing.
• Mental Disorders.
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19. Action Potentials (AP)
• APs are caused by an exchange of ions
across the neuron membrane and an AP is
a temporary change in the membrane
potential that is transmitted along the
axon.
• The conduction velocity of action
potentials lies between 1 and 100 m/s.
APs are initiated by many different types of
stimuli; sensory nerves respond to many
types of stimuli, such as chemical, light,
electricity, pressure, touch, and stretching.
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20. Action potentials processes
1. The action must be more than gate
threshold value.
2. Depolarization .
3. Sodium gates close.
4. Potassium gates open.
5. Repolarization.
6. Hyperpolarization.
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21. EEG Generation
 EEG signal is measured of current flow of
dendrites of neurons in cerebral context.
 Brain cells active mode (get a new action
potential), the cell produced within dendrites
so this current generate a magnetic field
(EMG) that cover over scalp.
 By the anatomical of the human head we
found that it consists of three main layers.
• 1-scalp
• 2-skull drjma

22. Brain Rhythms
Brain rhythms is depend on EEG
signals .
The amplitudes and frequencies of
such signals change from one to
another.
This waves from low to high (alpha ,
theta, beta ,delta ,gamma)
The history about found this
frequencies.
Draft that show the frequencies' of this
signals.(figure 1.7)
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24. Agenda
• Introduction.
• History.
• Neural Activities.
• Action Potentials.
• EEG Generation.
• Brain Rhythms.
• EEG Recording and Measurement.
• Conditioning the Signals.
• Abnormal EEG Patterns.
• Ageing.
• Mental Disorders.
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25. EEG Recording and
Measurement
Signal
EEG FMRI MEG
• EEG :- Electroencephalogram.
• FMRI:- Functional Magmatic
Resonance imaging.
• MEG:- Magnetoencephalogram.
The functional and physiological changes within
brain can registered by EEG,MEG and FMRI.
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26. The reasons of not using FMRI
about using EEG,MEG
1) Time resolution of FMRI image is very low
(2 frames/sec).EEG bandwidth can be
viewed using EEG or MEG signal.
2) Many types of mental activities brain
disorders cannot be registered using
FMRI.
3) Accessibility of FMRI systems is limited
and costly.
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27. EEG system consists of
Electrodes Amplifiers Filters Needle
To convert from analog signal to digital signal:-
1) Sampling.
2) Quantization.
3) Encoding.
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29. Characteristics of EEG signal:-
Note
If data volume is increased then the
number of bits increase.
 Effective bandwidth of EEG signal
approximately 100 HZ.
 Minimum frequency 200 sample/sec.
 Higher resolution (brain activities)=2000
sample/sec.
1 sample 16 bit
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30. Note
Although the format of reading the EEG data may be different for
different EEG machines, these formats are easily convertible to
spreadsheets readable by most signal processing software packages
such as MATLAB.
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31. Different types of electrodes:-
1) Disposable (gel-less, and pre-gelled
types).
2) Reusable dice electrodes (gold ,silver,
stainless steel or tin).
3) Headbands and electrode caps.
4) Saline based electrodes.
5) Needle electrodes.
 For multichannel recordings with a large
number of electrodes, electro caps are
often used.
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32. Conditioning the signals
• The row EEG signal have amplitudes of
order of micro volts and contain frequency
components up to 300 HZ.
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33. Filters
• Are used to make suitable for processing
and visualization.
Is divided to:-
1) High pass filter:-
remove distributing very low
frequency components.
2) Low pass filter:-
remove distributing very high
frequency components.
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34. Categories abnormal EEG
patterns:-
 Widespread intermitted slow wave
abnormalities.
 Bilateral persistent EEG.
 Focal persistent EEG.
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35. 1) Widespread intermitted slow wave abnormalities:-
• which is attenuated by alerting the individual and
eye opening, and accentuated with eye closure,
hyperventilation, or drowsiness.
2) Bilateral persistent EEG:-
• the phenomenon in different stages of impaired,
conscious:-
3) Focal persistent EEG:-
• these abnormalities may be in the form of distortion
and disappearance of normal patterns, appearance
and increase of abnormal patterns, or
disappearance of all patterns, but such changes
are seldom seen at the cerebral cortex.
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36. Agenda
• Introduction.
• History.
• Neural Activities.
• Action Potentials.
• EEG Generation.
• Brain Rhythms.
• EEG Recording and Measurement.
• Conditioning the Signals.
• Abnormal EEG Patterns.
• Ageing.
• Mental Disorders.
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37. Ageing
• The ageing process affects the normal
cerebral activity in waking and sleep, and
changes the response of the brain to
stimuli.
• The charges stem from reducing the
number of neurons and due to a general
change in the brain pathology.
• General cause for ageing of brain may be
decrease in cerebral blood flow.
• The REM duration decrease during the
night.
• Dementia increases dramatically with
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ageing.

38. Agenda
• Introduction.
• History.
• Neural Activities.
• Action Potentials.
• EEG Generation.
• Brain Rhythms.
• EEG Recording and Measurement.
• Conditioning the Signals.
• Abnormal EEG Patterns.
• Ageing.
• Mental Disorders.
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39. Mental Disorders
• Is divided to
Dementia Epileptic Psychiatric
Seizure and Disorders
No epileptic
attacks
External
Effects
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40. 1) Dementia
• Dementia is a syndrome that consists of a
decline in intellectual and cognitive
abilities this consequently affects the
normal social activities, mode, and the
relationship and interaction with other
people. EEG is often used to study the
effect of dementia; EEG signal can be
used to detect the abnormality.
Dementia is classified into
 Cortical dementia such as Alzheimer's
disease (AD).
 Sub cortical dementia forms such as
Parkinson's.
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41.  Generally
 Sub cortical dementias introduce less abnormality to
the EEG patterns than the cortical ones.
 EEG is usually used in the diagnosis and evaluation
of many cortical and sub cortical.
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42. 2) Epileptic Seizure and Non-
epileptic Attacks
• Often the onset of a clinical seizure is
characterized by a sudden change of
frequency in the EEG measurement.
• The abnormalities may be due to
psychogenic changes, variations in body
metabolism or circulstory insufficiency.
The most important ones are periodic or
quasi-periodic discharges related to serve
CNS diseases.
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43. • Despite the epileptic form signals there are spikes
and other paroxysmal discharges in healthy non
epileptic persons. These discharges may be found
in healthy individuals without any other symptoms
of diseases. They may appear during periods of
particular mental challenge on individuals, such as
soldiers in the war front line, pilots, and prisoners.
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44. 3) Psychiatric disorders.
• Not only can functional and
certain anatomical brain
abnormalities be investigated
using EEG signals,
pathophysiological brain
disorders can also be studied
by analysing such signals.
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45. 4)External Effects
EEG signal patterns may significantly
change when using drugs for the treatment
and suppression of various mental and CNS
abnormalities. Variations in EEG patterns
may also arise by just looking at the TV
screen or listening to music without any
attention. However, among the external
effects the most significant ones are the
pharmacological and drug effects.
Therefore, it is important to know the effects
of these drugs on the changes of EEG

46. Test Purpose Preparation Post- Nursing
Care
ElectroEnc Record Explain procedure Help client
ephaloGra electrical Done by technician in a quiet remove paste
m activity of room from hair
brain Painless Admin prescribed
Tranquilizer & stimulant meds meds w/held b4
w/held for 24-48 hrs pre-EEG EEG
Maybe ask to hyperventilate 3- Observe for
4 mins and watch bright, seizure activity in
flashing light seizure prone
Meals not w/held patients.
Kept awake night b4 test
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47. “Learners’ are learning from experiences they have experienced which cannot
be taught by teachers except themselves.”- Dr. James M. Alo
Shockran!