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BIOPAC
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Lesson 4
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Alpha Rhythms in the occipital lobe
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Associate Professor
Indiana University School of Medicine
Purdue University School of Science
36-V49
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Ph.D.
Biologist
BIOPAC Systems, Inc.
William McMullen
Vice President
BIOPAC Systems, Inc.
BIOPAC Systems, Inc.
42 Aero Camino, Goleta, CA 93117
(805) 685-0066, Fax (805) 685-0067
Email: info@biopac.com
Web Site: http://www.biopac.com
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Biopac Student Lab
Page 14
v.
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DATA ANALYSIS
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.. F~ST TRAC~ Data AnfliY!>is ....
Detailed Explanation
Entei.the ·~~~ew Savei"b.~~()d~~Enter
I. .
-..
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of Steps
~
the Review Saved Data mode from the Lessons menu.
~
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desigrtatioris:
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Fig 4.10
2.
Setup your display windowforoptimal
viewing of the entire recording:
tools help you adjust the data window:
The following
Autoscale
horizontal
Zoom Previous
Autoscale
waveforms
Horizontal(Time)
Zoom Tool
Vertical
3.
Set up the measurement boxes as
foUows:
stddev
CH40
stddev
CH41
mean
CH40
Freq
from the
The measurement
boxes are above the marker region in the data
window. Each measurement has three sections: channel number,
measurement
type. and result. The first two sections are pulldown menus that are activated when you click on them.
Channel Measurement
cn I
Scroll Bar
Preferences
Turn Grids ON and OFF by choosing
File menu.
W
Scroll Bar
(Amplitude)
Brief definition
of measurements:
iW
stddev: standard
deviation will be higher if there is a lot of
activity and lower if there is less. The advantage of the stddev
measurement
is that extreme values or artifacts do not unduly
influence the measurement.
mean: displays the average value in the selected area.
Freq: converts the time segment
frequency in cycles per second
of the selected area to
Note: The Freq measurement applies to all channels since
it is calculated from the horizontal time scale.
The "selected area" is the area selected
(including the endpoints).
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nata Anal~'sis continues ...
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Lesson 3: EEG I
Page 2
Biopac Student Lab
I. INTRODUCTION
The brain is encased by the cranium, bones of the skull which immediately cover and protect
brain surfaces. A thin cover of skin, called the scalp, covers most of the cranium. The largest part
of the brain immediately beneath the bones of the cranium is the cerebral cortex. The cerebral
cortex is composed of nerve cells (neurons), many of which are functionally connected to each
other. and connected to other parts of the brain. Electrical activity in the form of nerve impulses
being sent and received to and from cortical neurons is always present even during sleep. In a
biological sense (as well as a medical or legal sense), absence of electrical activity in the human
cerebral cortex signifies death.
Functions of the cerebral cortex include abstract thought reasoning, voluntary and involuntary
control of skeletal muscle, and the recognition and differentiation of somatic, visceral. and
special sensory stimuli. Specific regions of the cerebral cortex process or generate various kinds
of information. For example, the occipital lobe processes visual information while the parietal
lobe processes somatosensory information such as cutaneous pain or temperature (Fig 3.1).
Central sulcus
Frontal lobe
Parietal lobe
Occipital
lobe
Cerebellum
Temporal
lobe
Fig 3.1 Regions of the brain
The sensory information is relayed from the periphery through lower centers in the brain, and
then the information is sent to various regions of the cerebral cortex. Since the cerebral cortex is
just under the cranium, electrodes placed on the scalp above the various regions of the brain can
detect the electrical activity associated with functioning neurons. The recording of the brain's
activity obtained by using electrodes is called electroencephalogram
or EEG (electro =
electrical. cnce pheh: = brain. gram = record).
An ITer electrode will mainly detect the activity in the brain region just under it. Nevertheless,
the electrodes receive the activity trom thousands of neurons. In fact. one square millimeter of
cortex has more than 100,000 neurons. Since each region of the cerebral cortex of an alert person
is busy receiving, integrating. and sending many impulses. this activity is detected in the I·T(I.
(For more information about waveforms. see the Orientation chapter.)
Lesson 3: EEG I
Biopac Student Lab
Page 3
It is only when the input to a region is synchronized
time that you begin to distinguish
ln
IiJ::.l
with electrical activity occurring
simple, periodic waveforms in an EEG.
at the same
1929, an Austrian physician named Hans Berger discovered that electrodes placed on
the scalp could detect various patterns of electrical activity. After verifying that the
recordings were indeed recording from the brain, and were not artifacts of muscle or
scalp, scientists began to study these "brain waves". Today, the EEG is still a medically
useful recording for brain function. In medical and basic research, the correlation of
particular brain waves with sleep phases, emotional states, psychological profiles, and
types of mental activities is onqoinq.
Four simple periodic rhythms recorded in the EEG are alpha. beta, delta, and theta. These
rhythms are identified by frequency (Hz or cycles/see) and amplitude (Table 3.1). The
amplitudes recorded by scalp electrodes are in the range of microvolts (~V or 1/1.000,000 of a
volt).
Table 3.1 Typical Frequencies
and Amplitudes
of Synchronized
Brainwaves
o
Typicai Amplitude (JlV)
alpha
8-13
20-200
beta
13-30
5-10
delta
1-5
20-200
theta
4-8
10
Note: The amplitude
measurements
shown in Table 3.1 are those values
reported in clinical settings. In a classroom setting. the amplitudes may be
much lower.
Alpha
The four basic rhythms have been associated with various states. In general. the alpha rhythm is
the prominent EEG wave pattern of an adult who is awake but relaxed with eyes closed. Each
region of the brain has a characteristic alpha rhythm but alpha waves of the greatest amplitude
are recorded from the occipital and parietal regions of the cerebral cortex. Results from various
studies indicate that:
).>
females tend to have higher mean frequencies
of alpha waves than males
);. alpha wave amplitudes
are likely to he higher in "outgoing"
,.
vary with the subjects
alpha wave amplitudes
the eyes closed
attention
subjects
to mental tasks performed
with
In general. amplitudes of alpha waves diminish when subjects open their eyes and are attentive to .
external stimuli although some subjects trained in relaxation techniques can maintain high alpha
amplitudes even with their eyes open.
-Lesson 3: EEG I
Page 4
Biopac Student Lab
Beta
Beta rhythms occur in individuals who are alert and attentive to external stimuli or exert specific
mental effort, or paradoxically, beta rhythms also occur during deep sleep, REM (Rapid Eye
Movement) sleep when the eyes switch back and forth. Notice that the amplitude of beta rhythms
tends to be lower than for alpha rhythms. This does not mean that there is less electrical activity,
rather that the "positive" and "negative" activities are starting to counterbalance
so that the sum
of the electrical activity is less. Thus, instead of getting the wave-like synchronized pattern of
alpha waves, desynchronization
or alpha block occurs. So, the beta wave represents arousal of
the cortex to a higher state of alertness or tension. It may also be associated with "remembering"
or retrieving memories.
Delta and Theta
Delta and theta rhythms are low-frequency EEG patterns that increase during sleep in the normal
adult. As people move from lighter to deeper stages of sleep (prior to REM sleep), the occurrence
of alpha waves diminishes and is gradually replaced by the lower frequency theta and then delta
rhythms.
Although delta and theta rhythms are generally most prominent during sleep, there are cases
when delta and theta rhythms are recorded from individuals who are awake. For example. theta
waves will occur for brief intervals during emotional responses to frustrating events or situations.
Delta waves may increase during difficult mental activities requiring concentration.
In general.
the occurrence and amplitudes of delta and theta rhythms are highly variable within and between
individuals.
Electrode positions
Electrode
positions
have been named according
to the brain region below that area of the scalp:
and occipital. In the bipolar method. the EEG is
measured from a pair of scalp electrodes. The pair of electrodes measures the difference in
electrical potential (voltage) between their two positions above the brain. A third electrode is put
on the earlobe as a point of reference. 'ground". of the body's baseline voltage due to other
electrical activities within the body. In todays lesson. you will record an ErG using the bipolar
method.
frontal. central (sulcus). parietal. temporal.
Biopac Student Lab
Page 2
I. INTRODUCTION
The brain constantly receives sensory input and integrates the information. The sensory infonnation is
relayed from the periphery through lower centers in the brain, and then the information is sent to specific
regions of the cerebral cortex where it is processed. For example, the occipital lobe processes visual
information while the parietal lobe processes non-visual. sensory information such as cutaneous pain
(Fig 4.1). If you choose to, you can direct your attention to particular bits of sensory information: you can
access memories associated with the sensory information: or you can selectively ignore this sensory
input.
Central sulcus
Parietal lobe
Frontal lobe
Occipital lobe
Temporal lobe
Fig.4.1
The blood/brain
barrier separates cerebral spinal fluid from the blood. Oxygen. glucose. and carbon
dioxide can cross the blood/brain barrier, but the hydrogen ion can not. The brain requires oxygen and
glucose for energy. Without a relatively constant source of oxygen and glucose. the brain ceases to
function. Levels of carbon dioxide in the spinal fluid can change the pH of the spinal fluid, which can in
turn change the body's respiration rate.
Because brain activity is related to ions and charge movement. this activity can be detected by
electrodes.
The record of the brain's activity is called an electroencephalogram
(EEG) from the root
words of electro (electrical), encephala (brain). and ~"(/II/ (record).
The EEG records
variable between
Simpler patterns
cortex. The more
~
\
-
the electrical activity on the surface of the cerebral cortex.
adults, although under certain conditions, the EEG exhibits
in the EEG occur when many cells synchronize
their input
synchronized
the charge movement. the more rhythmic the
The EEG is complex and
simpler. rhythmic activity.
to the surface of the cerebral
EEG.
Your EEG changes as you grow. The development of EEG is rapid with newborns. As
neural development proceeds, the EEG recorded from the posterior regions of the brain
of an infant of 3-4 months begins to resemble EEGs recorded from the posterior region of
adults. The difference is that the 3-4 month old infants have EEGs in the frequency range
of 3-4 Hz, whereas adults tend to have average frequencies of 10Hz. By the time the
infant is one year old, the posterior region EEG is approximately 6 Hz, by three years, 8
Hz, and by 13-14 years (puberty), the average frequency is 10 Hz (similar to adults).
One of the simpler
patterns
is the alpha
rhythm.
The alpha rhythm
is characterized
by a frequency
of 8-
I J Hz and amplitudes of 20-200 p V. Each region of the brain has a characterist ic frequency of alpha
rhythm. Alpha waves of the greatest amplitude tend III he recorded from the occipital and parietal regions
of the cerebra I cortex.
Lesson 4: EEG II
Page 3
Just as the EEG is variable depending on the mental state of an individual, the frequency and amplitude
of alpha rhythms within an individual change. In general, the alpha rhythm is the prominent EEG wave
pattern of an adult in a relaxed, inattentive state with eyes closed.
More specific conditions of alpha rhythms are listed below:
>-
Hyperventilation (breathing abnormally quickly and deeply) causes the gas
composition of the blood to change. During hyperventilation, the carbon dioxide
levels of the blood fall, pH levels increase, and blood pressure decreases. These
effects of hyperventilation are associated with changes in brainwave activity. With
hyperventilation, the overall electrical activity of the brain increases, with the
amplitude of the alpha rhythms often increasing as well.
>-
Females tend to have higher mean frequencies of alpha waves than males, although
the differences are small.
);>
Frequency may affect the speed of "remembering" during memory tests and may be
approximately I Hz higher for high-scoring subjects than subjects who scored lower.
,
Amplitudes tend to be higher in subjects who are more "outgoing" and extroverted.
~
Amplitudes vary with the difficulty of mental tasks performed with the eyes closed.
,
Amplitudes of alpha waves diminish when subjects open their eyes and are attentive
to external stimuli. Thus, instead of getting the wave-like synchronized pattern of
alpha waves, desynchronization occurs .
.,
Amplitudes increase when subjects are less alert and tend to be higher from 1:304:30 p.m.
In this lesson, you will record the EEG and alpha rhythm under several conditions. At the same time. the
root-mean-squared of the alpha rhythm (aJpha-RMS) and an "alpha thermometer" will be displayed.
Alpha-RMS and the "alpha thermometer" are indices of the activity levels of the alpha rhythm.
II. EXPERIMENTAL OBJECTIVES
I)
To record an EEG from an awake. resting subject under the following conditions:
a)
Relaxed with eyes closed:
b) Performing mental arithmetic with eyes closed:
2)
c)
Hyperventilating (breathing quickly and deeply) with eyes closed:
d)
Relaxed with eyes open.
To examine differences in the level of alpha rhythm activity during mental arithmetic and
hyperventilation. compared to the control condition of eyes closed and relaxed.
Page 4
Biopac Student Lab
III. MATERIALS
~
BIOPAC electrode lead set (SS2L)
,.
BIOPAC disposable vinyl electrodes (EL503), 3 electrodes per subject
,.
BIOPAC electrode gel (GEL I) and abrasive pad (ELPAD)
or
Skin cleanser or alcohol prep
,.
Lycra" swim cap (such as Speedo" brand) or supportive wrap (such as 3M Coban"
Self-adhering Support Wrap) to press electrodes against head for improved contact.
;-
Cot or lab table and pillow
,.
Computer system
.,
Biopac Student Lab software v3.6.7 PC or v3.0.7 Mac or greater
.,
BIOPAC acquisition unit (MP30)
,.
BIOPAC wall transformer (ACIOOA)
.,
BIOPAC serial cable (CBLSERA) or USB cable (USB IW) if using a USB port.
Page 5
Lesson 4: EEG II
IV.
EXPERIMENTAL METHODS
Overview
)0>
As you complete the Experimental
Methods (Set Up, Calibration, and Recording) and the Analysis,
you may need to use the following tools and/or display options. The window display shown below is
only a reference sample - it does not represent any lesson specific data. The sample screen shows 3
channels of data and four channel measurement
boxes, but your screen display may vary between
lessons and at different points within the same lesson.
channel measurement boxes
(channcl e
measurementrype resuh)
marker
marker tools
JohnB.102
channel boxes
(Data analysis Illude only)
1_.. .
I
J
•
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1859t~
!J!i r:orc.
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Jl
J.3 P"
vertical scales
o
marker label
4IJOOOO~
~~-------------------~-ooooo
channel labels
vertical (amplitude)
scroll bar
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ra eeo
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j=
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...
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selection tool
horizontal (time) scroll har
horizontal scale
,
The symbols
m
explained
Experimental
•..
zoom tool
I-Beam cursor
Methods
and Analysis.
Key to Symbols
If you encounter
Orientation
!IilI
below are used throughout
'<'
.~
>UO
•• c:orods
a problem
Chapter
The data collected
or need further explanation
of a concept.
refer to the
for more details.
in the associated
step needs to be recorded
in the Data Report (in the
section indicated by the alpha character). You can record the data individually by hand or
choose Edit> Journal>
Paste measurements
to paste the data to your journal for future
reference.
V
,
Most markers and labels are automatic. Markers appear at the top of the window as
inverted triangles. This symbol is used to indicate that you need to insert a marker and key
in a marker label similar to the text in quotes. You can insert and label the marker during
or after acquisition. On a Mac. press "ESC" and on a Pt,', press "F9:'
Each section
is presented
FAST TRACK
in a two-column
STEPS
This side of the lesson (left, shaded
column) is the "fAST TRACK"
through the lesson, which contains a
basic explanation of each step.
format. as described
below.
DETAILED EXPLANATION OF STEPS
This side of the lesson contains more detailed
information to clarify the steps and/or concepts in the
FAST TRACK. and may include reference diagrams.
illustrations. and screen shots.
Page 6
A.
Biopac Student Lab
SET UP
Detailed
The desktop
appear.
Explanation
should appear on the monitor.
ask the laboratory
instructor
Plugs into Channel
.-
.·<:;t~~;>·
.'.
for assistance.
W
I
't-~~
.:~(:-
4. _'T~ritjlieM~J,O Data:'Atquisition
/y --
SS2L Electrode Lead Set
Fig. 4.2
Unit ..
5.
Have thesubject
position.
6,
Position electrodes on the scalp. Fig
4.3 shows a sample configuration.
~==IMPORT
If it does not
.Y- .
..:;.,:.,..r ..,
ON.:'.'· - . -
of Set Up Steps
assume a relaxing .
A supine position with the head resting comfortably but
tilted to one side is recommended.
The best recordings occur
when the subject is relaxed throughout the session.
RED Lead
AN~T~~§I~I
Electrode adhesion to the scalp is
crucial for obtaining a meaningful
EEG recording.
Fig. 4.3
Hints for obtaining
optimal
data:
I.
As much as possible. move the hair <may from the
electrode adhesion area. Otherwise the hair will pull the
electrodes up, away from the scalp .
..,
Apply pressure to the electrodes
the initial placement.
1
Subject should try to remain still because blinking and
other movement \\ ill affect the recording of all four
for about I minute alter
rhv thms.
t
t
liiiiiiiiiiiiiiSiil'iiiil;;;;illii;)
iiciioiinii
iiinii"iil'iisii'
'ii'iiiiiiiiiiiiil
--L Despite your best efforts. electrode adhesion may not be
strong enough to record data. If so. another subject or
different electrode placement may be necessary.
--
Lesson 4: EEG II
Page 7
5.
Wrap the subject's head to secure electrode placement.
Guidelines for electrode placement:
a)
W
The placement of the scalp electrodes can vary (within
limits) depending on your instructor's or the subject's
preference.
b) Keep the electrodes on one side (right or left) of the
head.
c)
For this lesson, you will focus on the occipital lobe, and
should use a placement similar to Fig. 4.3.
d) The third electrode is the ground electrode and is
connected to the earlobe (position "c"), Although the
adhesive collar is larger than the earlobe, it can be
folded under the ear for proper adhesion. Alternately,
the ground electrode can be placed on the facial skin
behind the earlobe.
The pinch connectors work like a small clothespin, but only
latch onto the nipple of the electrode from one side of the
connector.
Drape the electrode cables over the head so that they are not
pulling on the electrodes.
Place a Lycra" swim cap or supportive wrap on the Subject's
head to press the electrodes against the scalp with a constant
pressure. Subject should not hold electrodes against scalp.
Ideally, the room should be reasonably quiet to help the
subject mentally relax. This 5-minute period is also
important to give the electrodes time to establish contact
with the surface of the skin.
11. Choose Lesson 4 (L04-E.EG.;.2).
:.
.
",
::"'.
":
.
12. Type in your filen~e.
Use a unique idcntificr.lW
! ,"'
13. Click OK.
I••••__
E_N_D_O_F_S_E_T__U_P ••
w
w
~_I
This ends the Set Up procedure.
Page 8
B.
Biopac Student Lab
CALIBRATION
The Calibration procedure establishes the hardwares internal parameters (such as gain, offset, and
scaling) and is critical for optimum performance. Pay close attention to the Calibration procedure.
Detailed Explanation
The Calibrate
window.
of Steps
button is in the upper left comer of the Setup
A window will pop up, requesting that you check the electrode
attachments one last time.
This will begin the calibration procedure. The BIOPAC Student
Lab will begin recording data and use it to calculate optimal
settings for the subject. The calibration procedure will stop
automatically after 8 seconds.
At the end of the 8-sec calibration recording, your screen should
resemble Fig. 4.4.
:'.'
. -'
/"-.
~
.
"
n
t-.·.··
R.,ord]
104-((6-1
I Redo Calibration 1
1000
...'.<~~i·
500 0
•••..••••
§~~----------------------------------~oooo
:J
.... j: ..
.... .::
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I.
i.:
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ift~'
-500 0
-1000
00
•
l'I 110.
.00
00
I(
Fig. 4.4
the.Data
~
If similar. proceed to
Recording section.
~
If different, Redo Calibration.
I
END OF CALIBRATION
There should be a relatively flat line (as in Fig. 4.4).
I
If the data shows any large spikes, then you must redo
calibration by clicking on the Redo Calibration button and
repeating the entire calibration sequence.
•
Page 9
Lesson 4: EEG II
C.
RECORDING LESSON DATA
Detailed Explanation
of Steps
You will record the Subject
in four conditions: the Subject
perform tasks in the intervals between recordings.
Segment
I-
Relaxed
Segment
2-
Performing
mental math with eyes closed
Segment
3-
Recovering
closed
from hyperventilation
Segment
4 -
Relaxed
will
with eyes closed
with eyes
with eyes open.
In order to work efficiently, read this entire section so you will
know what to do for each recording segment.
The Subject should remain in a supine position
relax while you review' the lesson.
and continue
to
Check the last line of the journal and note the total amount of
time available for the recording. Stop each recording segment as
soon as possible so you don't use an excessive amount of time
(time is memory).
-"00-.
rn
Hintsfor obtaining optimal data:
a)
It is important that you pay attention to the specific
instructions for each recording segment.
b)
Good electrode contact is essential
and increase signal amplitude.
c)
The Subject should lie still and should not blink during
the "eyes open" segment. Best results are obtained if the
eyes remain still at all times.
d)
The Subject should not talk during any of the recording
segments. and should not verbalize answers to the
mental arithmetic.
e)
The alpha signal will be increased during the relaxation
segment if the Subject concentrates on breathing slowly
and/or relaxing muscles.
t)
For the mental math segment: the Director
should
prepare by coming up with a math problem before
recording begins. The math problem should be
challenging but not too difficult. e.g. take the number
two and double it. double again. double again. divide by
three. multiply by fifteen. divide by seven. multiply by
twelve. The point is to make the Subject really work to
get the answer. not to stump the Subject or make them
give up. The math problem should require a minimum of
twenty seconds.
to minimize
noise
Before the recovery from hyperventilation
segment: the
should breath quickly and deeply for two
minutes. as if they had just finished exercising and
needed air. The Subject should not be hyperventilating
during the recording.
liiiiiiiiiiiiRiiiiieiiciioiirdiiiiiin;;igi;;;;;;ciioiiniitiiiniiuiieiisii'ii"iiiiiiiiii;;;;i~
g)
Subject
Page 10
Biopac Student Lab
Subject relaxed with eyes closed (Control)
The recording
will begin.
Note: The graph window will resize and the Input values
window will appear on the right side of the graph window.
The Input values window displays the alpha-RMS value in a
thermometer-like
bar display. and can be used as a visual aid
to determine fluctuations in alpha-RMS activity. It is only
displayed when data is recorded, and does not show in the
Review Saved Data mode.
llOi! Input lJolues ~0~
~
/;~;{'y!,i\,f ..,..•.....•.
."
~ ,~,,~.~:~::.~.
'.
.:;/.:
. ".:. i."; •
Fig. 4.5
3.· .Record for 10 seconds.
Subject
4. : Click on Suspend.
The recording should halt. giving you time to review the data
and prepare for the next recording segment.
5:.' Review the data on the screen.
If all went well. your data should look similar to Fig. 4.6 and
you can proceed to Step 6.
l···.·
-.'
~; .If cotrect, go to Step 6.
with eyes closed (seconds 0-10).
should be relaxed
;0
".a,.
n ncoe
sc
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l04 [(6 2
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1=
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0
s:
-0.0000
~
0
20.00
~
---------
0
1000
,
J
soo ---------
0.000
'00
seconds
IQI
Fig. 4.6 Relaxed.
~
If incorrect, click on Redo.
L"III~
'50
¢I
The data would be incorrect
ell;}]
Eyes Closed
if:
a)
the suspend
button was pressed
prematurely
b)
an electrode peeled up causing
spike. or loss of signal.
c)
the subject did not follow the proper procedure.
d)
The subject
a large baseline drift.
had too much EMG artifact.
In this case. you should redo the recording. by clicking. on
"Redo" and repeating Steps 2-5. Note that once you press Redo.
the data you have just recorded will be erased.
I
Recording continues.,;
~~~~
•
--
Lesson 4: EEG II
Page 11
Performing Mental Mat"
Director prepares the math problem (see Hints above).
Subject remains relaxed with eyes closed.
The recording will continue from the point where it last stopped,
and a marker labeled "Mental Arithmetic" will automatically
come up when Resume is pressed.
Director should give the Subject a set of mental arithmetic
problems.
Subject should perform mental arithmetic as posed by the
Director and keep eyes closed.
Subject is performing mental math (seconds 11-30).
The recording should halt, giving you time to review the data
and prepare for the next recording segment.
If all went well, your data should look similar to Fig. 4.7 and
you can proceed to Step 12.
10
LD4 [[6-2
Resume I ~
[Done]
sc j •.••••I-
5cl •••••
1=
~=
Mento I Ari thllletic
w~~-
-
.•••..•
.....-{-o.oo
f-=r+-
-ij;~::
...,_o.oooo 3
L'*o
o
f-o+-.
.•......•c.'
=5 ~
=ft
-+-__
~:;
-:
---------------------1':::20""'.00::::--,,;:,:;
I~~
~./'15.0
~.~onds
~
2S
0
'-oooo'~
30
0
X
n
IQ.
Fig. 4.7 Mental Math, Eyes Closed
)or
If incorrect. click on Redo.
The data would be incorrect for the reasons in Step 5.
If incorrect, you should redo the recording by clicking on
"Redo" and repeating Steps 7-1 I. Note that once you press
Redo, the data you have just recorded will be erased.
I
Recording continues...
~iiiiiiiiiiiiiiiiiiiiiiiiiiiiii_
I
Page
Biopac Student Lab
\2
Segment J
12.
After Hyperventilation
Director.~~v!~.,§~~~~t~:.~~,~
..\:·.. _
hyperven~~a~~ -(<?i·~9.~JIiMf~··
~'t~
..(.
1P__
iiiiiiii.W_AiiiiiiiiRi!N!!!!I.N.G
iiiiiiiiii!!!iii!!I'"
Hyperventilation can make the
Subject dizzy and light headed.
The Subject should be sitting
down, and the Director should
be watching him/her. Stop the
procedure if the Subject starts
to feel sick or dizzy .
....•.
Director advises Subject to hyperventilate
Subject should Hyperventilate
(see Hints).
for two minutes
with eyes closed.
It is important that you Resume recording as quickly as possible
after the Subject has hyperventilated.
However, it is also
important that you do not click Resume while the Subject is
hyperventilating
or you will capture EMG artifact.
"
13.ClickonR"~~.;~~:,
The recording will continue from the point where it last stopped.
and a marker labeled "After Hyperventilation"
will
automatically
come up when Resume is pressed.
14.Record
Subject should be in a relaxed state with eyes closed. recovering.
10~~b~alfhiesubjectis
for
recovering from h)yef\;entilati.on.
15. Click on Suspend.
from hyperventilation.
..
The recording
next recording
16. Review the data on the screen.
should halt. giving you time to prepare
segment.
II' all went well. your data should
you can proceed to Step 17.
~D
for the
look similar to the Fig. 4.8 and
l04-HG
0~
2
Resumel~~
@]~=
@]~.
~:
vf~
~
If correct, go
to' Step
17.
h',IPet'"venti
I ~ 1.\ ..•.
lotion
0-
,
w
•
~
-000
'5
0
J:
-0 DODD
'5 "'"
0
2000
0
'l5
""""
"iI'-.~/-~-.~/---~'J
20.0
¢I><C<
25 0
.... /,.,:
..
,
Fig. 4.8 Recovering
~
If incorrect. click on
Redo.
'~~~
30 0
seconds
'il'"
40.0
for the reasons
Note: It is normal to have some baseline
hyperventilation.
as shown in Fig. -1.8.
you should redo the recording
3~
{)-
DI X 10..
.191
01
."iT
from Hyperventilation.
The data would he incorrect
If incorrect.
0.000
35.0
Eyes Closed
in Step 5.
drift after
by clicking
on
"Redo" and repeating Steps 12-16. Note that once you press
Redo. the data you haw just recorded will be erased.
I
Recording continues...
~~~iiiiiiiiiiiiiii~
•
-
Lesson 4: EEG II
Page 13
Eyes Open
Director should advise Subject to open his/her eyes.
Subject should remain relaxed but open his/her eyes.
The recording will continue from the point where it last stopped,
and a marker will automatically
come up when Resume is
pressed, but the Recorder needs to key in the marker "Eyes
Open" label.
Subject should be in a relaxed state with eyes open and try to
not blink.
The recording
should halt.
Ifall went well, your data should look similar to the Fig. 4.9 and
you can proceed to Step 22.
L04-EEG-2
l¥D
IResumel~~
sc I no,..
1=
ey~
[SC)non.J=
open
of~,.......
~ -
0-
[SC)non.J=
-
14 I ~IOY
~
:>
000
'V
0
s:
3
-0.0000
p
0
20.00
ti
I~~
~
35.0
3~00-
0.000
40.0
seconds
450
;)UU
¢
nII~
elQ:
¢I
Fig. 4.9 Relaxed,
The data would be incorrect
Eyes Open
for the reasons
in Step 5.
If incorrect, you should redo the recording by clicking on
"Redo" and repeating Steps 18-21. Note that once you press
Redo, the data you have just recorded will be erased.
A pop-up window with four options
choice, and continue as directed.
If choosing
2l. Remove the electrodes.
I
END OF RECORDING
I
the "Record
from another
will appear.
subject"
Make your
option:
a)
Attach electrodes per Set Up Step 5 and continue
entire lesson from Set Up Step 8.
b)
Each person will need to use a unique file name.
the
Remove the electrode cable pinch connectors, and peel off the
electrodes. Throw out the electrodes (BIOPAC electrodes are
not reusable). Wash the electrode gel residue from the skin,
using soap and water. The electrodes may leave a slight ring on
the skin for a few hours. This is normal, and does not indicate
that anything is wrong.
,--a
Lesson 4: EEG II
Page 15
t
Fig. 4.11 shows an example of the selected area. The first data
segment is the area from Time 0 to the first marker.
a
.0
t
t
lllilllamM-L04
t
••
••
a
a
a
a
Fig.4.11
'..>
~
.
.1;'_~•..•.
··.:;~:Jj[;.';i:'-',;f'.
6'. zoGnim on£smalf'secnoiiofthe
Be sure to zoom in far enough
frequency of the alpha wave.
7:' U~th~'I:'Beamcursor toselect an area
fromone ~ak to the next in the alpha
band [ell 40].
.
Fig. 4.12 shows a sample setup for measuring
the alpha band [CH 40].
S~gm~qtl(i~t4;,::,»,
~
~
eachof~e da~ Segm~nts..
~
.
so that you can easily measure
WllliamM·104
.0
-
the frequency
the
in
__
IllB
~
~
~
~
- .-.~~-
-
~'''oooo=-----T·:OO)=--~i7-'i-
seco-cs
~
Fig.4.12
~
•
•
•
•~
~
8.
Save or print the data file.
Y Oll may save the data to a floppy drive. save notes that are in
the journal.
or print the data file.
9. Exit the program.
I
END OF DATA ANALYSIS
I
~
~
~
~
~
~
~
I
I
I
Complete
ENIl OF LESSON 4
the Lesson 4 Data Report that follows.
Wi