SNR analysis of high-frequency steady-state visual evoked potentials from the foveal and extrafoveal regions of human retina.
With brain-computer interface (BCI) applications in mind, we analyzed the amplitudes and the signal-to-noise ratios (SNR) of steady-state visual evoked potentials (SSVEP) induced in the foveal and extra-foveal regions of human retina. Eight subjects (age 20-55) have been exposed to 2° circular and 16°-18° annular visual stimulation produced by white LED lights flickering between 5Hz and 65Hz in 5Hz increments. Their EEG signals were recorded using a 64-channel NeuroScan system and analyzed using non-parametric spectral and canonical convolution techniques. Subjects' perception of flickering and their levels of comfort towards the visual stimulation were also noted. Almost all subjects showed distinctively higher SNR in their foveal SSVEP responses between 25Hz and 45Hz. They also noticed less flickering and felt more comfortable with the visual stimulation between 30Hz and 45Hz. These empirical evidences suggest that lights flashing above the critical flicker fusion rates (CFF) of human vision may be used as effective and comfortable stimuli in SSVEP BCI applications.
Photonics Department and the Display Institute, National Chiao Tung University in Hsinchu, Taiwan, R.O.C. fclin.eo93g@nctu.edu.tw
Fang-Cheng
FC
Lin
John K
JK
Zao
Kuan-Chung
KC
Tu
Yijun
Y
Wang
Yi-Pai
YP
Huang
Che-Wei
CW
Chuang
Hen-Yuan
HY
Kuo
Yu-Yi
YY
Chien
Ching-Chi
CC
Chou
Tzyy-Ping
TP
Jung
D000328:Adult; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D005583:Fourier Analysis; D005584:Fovea Centralis / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D059629:Signal-To-Noise Ratio; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult