Brain-Computer Interface systems based on the
Steady-State Visual Evoked Potential
Presenter : Ching-Kai Huang
Adviser : Dr. Shih-Chung Chen
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Outline
Background
Introduction
Literature Reviews
Materials and Methods
Results & Discussion
Future Works
References
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Background
Four lobes of Cerebral cortex:
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
20 STROKECONNECTION July | August 2007
Keywords: Cerebral cortex , Frontal lobe, Parietal lobe, Temporal lobe, Occipital lobe
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Background
E.E.G(electroencephalogram):
An EEG records the electrical activity of the brain.
EEG features:
Voltage range: 0.5 ~ 100 μV
Frequency measure range: 0.5 ~ 100 Hz
The brain wave may be divided four basic waves:
α rhythm
β rhythm
θ rhythm
δ rhythm
http://www.fibromyalgiasyndrome.co.uk/images/19161.jpg
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Background
 The frequency and voltage range of four basic waves :
 α (Alpha)
 8~14 Hz；30~50μV;
 β (Beta)
 14~30 Hz；5 ~ 20μV ;
 θ (Theta)
 3.5~7 Hz；30μV <;
 δ (Delta)
 3.5 Hz<；100 ~ 200μV
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Introduction
Brain-Computer Interface (BCI)
Several different features of scalp recorded EEG signals are being used as control signals.
Feedback
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Introduction
Event Related Potential (ERP) is voltage fluctuations
that are associated in time with some physical or mental
occurrence.
 Components of Event Related Potentials include:
 μ and β Rhythm
 P300 Evoked Potential
 Steady-State Visual Evoked Potential
 Slow Cortical Potential
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Literature Reviews
G. Pfurtscheller, C.Neuper, “Motor Imagery and Direct Brain-Computer
Communication,” Proceedings of the IEEE, Vol. 89, 1123-1134, 2001.

Component of ERP: μ and β Rhythms
Donchin, E., Spencer, K. M. and Wijesinghe, R. S., “The mental prosthesis:
Assessing the speed of a p300-based brain-computer interface,” IEEE
Transactions on Rehabilitation Engineering, vol. 8, 174-179, 2000.

Component of ERP: P300 Evoked Potential
F. Beverina, G. Palmas, S. Silvoni et al., “User adaptive BCIs: SSVEP and
P300 based interfaces,” PsychNology Journal, vol. 1, no. 4, 331-354, 2003.

Component of ERP: Steady-State Visual Evoked Potential
G. Schalk, D. J. McFarland, T. Hinterberger, N. Birbaumer, and J. R. Wolpaw,
“BCI2000: A general-purpose brain-computer interface (BCI) system,”
IEEE Transactions on Biomedical Engineering, vol. 51, 1034-1043, 2004.

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Component of ERP: Slow Cortical Potential
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Literature Reviews
μ and β Rhythms
Event-Related Synchronization
 μ rhythms:10 ~ 12 Hz ； β rhythms:14 ~ 18 Hz
&
P300 Evoked Potential
•
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Event-Related Desynchronization
This event related potential (ERP) appears as a positive deflection of the
EEG voltage at approximately 300 ms.
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Literature Reviews
Steady State Visual Evoked Potential (SSVEP)
 These signals are natural responses for visual stimulations at specific frequencies.
 Separate frequencies were used for each arrows. (6 Hz and 10 Hz)
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Literature Reviews
Slow Cortical Potential (SCP)
•
These potential shifts occur over 0.5 ~ 10 s and are called slow cortical potentials.
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Material and Methods
Hardwares:
NuAmps - amplifier
Electrode caps
The hardwares include NuAmps amplifier, and the electrode caps , shown in Fig. 1 and Fig. 2.
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Material and Methods
The EEG recording for electrode cap with 37 channels, while the distribution of
means using the International 10 - 20 system of electrode placement.
International 10 - 20 system of electrode placement[5]
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Material and Methods
Software:
The software I used to acquire brain wave is
Scan 4.3 developed by NeuroScan company.
The other software I used to design human-machine interface is LabVIEW 2009 developed
by National Instruments company.
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Material and Methods
Parameters Setup
Sample rate:
1000 Hz
Filter:
Band Pass: 1Hz-30 Hz
Recording Channels:
Oz
Reference:
A2
Notch Filter:
60 Hz
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Material and Methods
ARM Wrestling:
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Material and Methods
The 9 x 9 stimuli matrix:
Start
SSVEP
BCI
No
The threshold
Yes
Display
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Material and Methods
The 9 x 9 stimuli matrix:
Start
SSVEP
BCI
No
The threshold
Yes
Display
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Material and Methods
Auto Power spectrum of SSVEP in response to 7 Hz stimulation.
Single Auto Power spectrum.
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Material and Methods
Auto Power spectrum of SSVEP in response to 10 Hz stimulation.
Single Auto Power spectrum.
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Material and Methods
The 9 x 9 stimuli matrix:
Start
SSVEP
BCI
No
The threshold
Yes
Display
If the threshold we defined, BCI system will output control command to the devices. Otherwise, BCI system will do nothing.
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Results & Discussion
The game close beta testing.
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References
[1] Serby Hilit, Yom-Tov Elad, Inbar, Gideon F. “An improved P300-based
brain-computer interface,” IEEE Transactions on Neural Systems and
Rehabilitation Engineering, v 13, n 1, p 89-98, March, 2005
[2] Christoph Guger, Shahab Daban, Eric Sellers, Clemens Holzner, Gunther Krausz,
Roberta Carabalona, Furio Gramatica, Guenter Edlinger, “ How many people are
able to control a P300-based brain–computer interface (BCI)? ” Neuroscience
Letters, Volume 462, Issue 1, Pages 94-98, 18 September 2009
[3] Gray Garcia, "High frequency SSVEPs for BCI applications,"ComputerHuman Interaction 2008,April 2008,Florence,Italy
[4] 趙倫(2004)，ERP實驗教程，天津：天津社會科學院。
[5] Pfurtscheller G, Lopes da Silva FH (1999) Biomedical Engineering, Vol. 51, NO. 6
“Event-related EEG/MEG synchronization and desynchronization: basic principles,
Clinical Neurophysiology vol. 110, 1842-2857.
[6] 基礎人體解剖與生理學
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References
[7] M. Cheng, X.R. Gao, S.K. Gao, and D.F. Xu, "Design and Implementation of a
Brain-Computer Interface With High Transfer Rates," IEEE Trans. Biomed. Eng.,
vol. 49, pp.1181-1186, 2002.
[8] G.R. Müller-Putz, R. Scherer, C. Brauneis, and G. Pfurtscheller, "Steady-state visual
evoked potential (SSVEP) -Based communication: Impact of harmonic frequency
components,"Journal of Neural Engineering, vol. 2, pp. 123-130, 2005.
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Future works
Papers review.
Let the game interface complete.
改善訊號干擾及閥值的判斷方式
縮短判斷時間
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Thanks for your attention.
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