Asynchronous BCI control using high-frequency SSVEP

Abstract

BackgroundSteady-State Visual Evoked Potential (SSVEP) is a visual cortical response evoked by repetitive stimuli with a light source flickering at frequencies above 4 Hz and could be classified into three ranges: low (up to 12 Hz), medium (12-30) and high frequency (> 30 Hz). SSVEP-based Brain-Computer Interfaces (BCI) are principally focused on the low and medium range of frequencies whereas there are only a few projects in the high-frequency range. However, they only evaluate the performance of different methods to extract SSVEP.MethodsThis research proposed a high-frequency SSVEP-based asynchronous BCI in order to control the navigation of a mobile object on the screen through a scenario and to reach its final destination. This could help impaired people to navigate a robotic wheelchair. There were three different scenarios with different difficulty levels (easy, medium and difficult). The signal processing method is based on Fourier transform and three EEG measurement channels.ResultsThe research obtained accuracies ranging in classification from 65% to 100% with Information Transfer Rate varying from 9.4 to 45 bits/min.ConclusionsOur proposed method allows all subjects participating in the study to control the mobile object and to reach a final target without prior training.

The Effect of the Viewing Distance of Stimulus on SSVEP Response for Use in Brain-Computer Interfaces

“…SSVEP based BCI is also classified as an asynchronous system, i.e. a self-paced system, which does not require a cue to operate it [9] and users can operate the BCI continuously.…”

Real and imaginary motion classification based on rough set analysis of EEG signals for multimedia applications

“…For example, delta waves (2-4 Hz) are related to consciousness and attention, theta (4-7 Hz) and alpha (8)(9)(10)(11)(12)(13)(14)(15) Hz) reflect thinking, focus, and attention. Moreover, by correctly positioned electrodes each functional part of the brain can be monitored separately, e.g.…”

“…Varying the flashing pattern for each icon is useful in applications with multiple choices. The latter approach allows for self-paced interaction, but it requires determining two states: non-control and control state, and then in the latter case classifying the type of control [9,39,50]. The asynchronous approach is evaluated in this work, the method and results of classification of left and right, and up and down motion intents are assessed, and possibility for control of a multimedia applications is discussed.…”

Review of real brain-controlled wheelchairs

“…Most systems used stimuli in the mentioned range of 5 to 20 Hz, with the exception of the study of Diez et al (50), in which they proved that it is possible to achieve an adequate control of a BCW using high frequencies (37)(38)(39)(40). The proposal of this study comes from the knowledge that highfrequency flickering stimuli produce less eye strain than low and medium frequencies (68), which is one of the main drawbacks of an SSVEP BCI.…”