Asynchronous BCI Control Using High-Frequency SSVEP
By Diez, Pablo F.; Mut, Vicente A.; Avila Perona, Enrique M.; Laciar Leber, Eric; Journal of NeuroEngineering and Rehabilitation, Vol. 8, No. 39Publication Date: July 14, 2011
Study attempted to control the navigation of a mobile object on a computer screen through different environments using an asynchronous Brain-Computer Interface (BCI) based on a high frequency Steady-State Visual Evoked Potential (SSVEP). A BCI is described as a system that helps impaired people to control a device such as a robotic wheelchair using their own brain signals obtained from the scalp as electroencephalographic (EEG) signals. SSVEP is defined as a visual cortical response evoked by repetitive stimuli with a light source flickering a frequencies above 4 hertz. It can be classified into three ranges: low, up to 12 hertz; medium, 12 to 30 hertz; and high frequency, above 30 hertz. Study participants were 1 woman and 5 men with a mean age of 32 years. Participants used the high-frequency SSVEP-based asynchronous BCI in order to control a mobile ball on a computer screen and navigate it through a scenario to reach a white square. There were 3 different scenarios with increasing difficulty levels. The signal processing method was based on Fourier transform, a mathematical calculation that breaks a signal down into its constituent frequencies, and 3 EEG measurement channels. Results showed participants obtaining accuracies ranging in classification from 65 to 100 percent with Information Transfer Rate varying from 9.4 to 45 bits per minute. The method allowed all participants to control the mobile object and to reach the final target without prior training.
Published by: BioMed Central Ltd (Website:http://www.biomedcentral.com)
Link to text: http://www.jneuroengrehab.com/content/pdf/1743-0003-8-39.pdf
