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Electroencephalography (EEG)
Amanda Spencer
Neuron
Action Potential
Raw EEG
0 2 4 6 8 10-80
-60
-40
-20
0
20
40
60
80
Time (s)
Vol
tage
(uV
)
EEG Raw Signal at Rest
4 4.5 5 5.5 6 6.5 7-80
-60
-40
-20
0
20
40
60
80
Time (s)V
olta
ge (u
V)
EEG Raw Signal at Rest
Frequency Domain
0 5 10 15-80
-78
-76
-74
-72
-70
-68
-66
-64
-62
Frequency (Hz)
Mag
nitu
de(d
B)
EEG Resting Frequency Spectrum
0 5 10 15-80
-78
-76
-74
-72
-70
-68
-66
-64
-62
Frequency (Hz)
Mag
nitu
de(d
B)
EEG Mental Math Frequency Spectrum
Areas of the Brain
Electrode Placement
Typical Waves
Name Frequencies Principal characteristics alpha 8-12 Hz seen when subject is relaxed with eyes are closed beta 13+ Hz seen in frontal during mostly during sleep theta 4-7 Hz seen during light sleep delta .5-3.5 Hz seen during deep sleep mu 7-11 Hz occur unless inhibited by movement lambda Sharp Waves sometimes occur in response to visual stimulation
1 1.5 2 2.5 3
-80
-60
-40
-20
0
20
40
EEG Raw Data Eyes Open
time(s)
Vol
tage
(uV
)
1 1.5 2 2.5 3
-80
-60
-40
-20
0
20
40
EEG Raw Data Eyes Closed
time(s)
Vol
tage
(uV
)
alpha
beta
theta
delta
mu
Evoked Potentials
0 50 100 150 200 250 300 350 400 450 500-6
-5
-4
-3
-2
-1
0
1
time(ms)
Vol
tage
(uV
)
EEG Average Auditory Evoked Potential
N2
N1
P2
Artifacts
Artifacts
0 2 4 6 8 10
-150
-100
-50
0
50
100
150
Time (s)
Vol
tage
(uV
)
EEG Eye Blink Artifacts
0 2 4 6 8 10
-150
-100
-50
0
50
100
150
Time (s)
Vol
tage
(uV
)
EEG Eye Movement Artifacts
0 2 4 6 8 10
-150
-100
-50
0
50
100
150
Time (s)
Vol
tage
(uV
)
EEG Head Movement Artifacts
0 5 10 15-80
-75
-70
-65
-60
-55
Spectra of Eye Blinks
Frequency(Hz)
Magn
itude
(dB)
0 5 10 15-80
-75
-70
-65
-60
-55
Spectra of Eye Movements
Frequency(Hz)
Magn
itude
(dB)
0 5 10 15-80
-75
-70
-65
-60
-55
Spectra of Head Movements
Frequency(Hz)
Magn
itude
(dB)
Montages
• Reference (ear)
• Bipolar
• Common Average
• Laplacian
– Small
– Large
