Investigation of the Effect of Attention in BCI systems based on Steady_State Visually Evoked Potential

Background and Aim : As Brain-Computer Interface (BCI) systems play an important role in improving the life quality of disabled people, designing reliable and applicable BCI systems is of great interest for neuroscientists. This research studies the effect of attention in BCI systems based on Steady-State Visually Evoked Potentials (SSVEP) . Brain-Computer Interface systems make a communication pathway between human and computer. One type of stimulus which is used in BCI systems is Repetitive Visual Stimulus (RVS). When an RVS is presented to the individuals, a Steady-State Visual Evoked Potential (SSVEP) would be elicited in their EEG signals. There are different methods for designing an SSVEP-based BCI system. In some methods the users must focus on the flickering stimulus while in others the main attention of the users is on another mental task and the flickering stimulus is not their main focus. In this paper, the role of attention in SSVEP detection is studied.Methods : A 23 years old woman (right-handed) without any neurological disease participated in this research. Two flickering stimuli at 10 Hz (alpha band) and 14 Hz (beta band) were utilized. The experiment had two parts. In the first part (attention condition) the participant was asked to entirely focus on the flickering stimulus. In the second part (inattention condition) she was asked to count numbers down from 9 to 0. The 32 channel EEG signal was recorded during these tasks. After preprocessing the signal power was calculated in two ranges of 9.8 to 10.2 and 13.8 to 14.2 for each stimulus. As the parametric condition was not satisfied, the Wilcoxon test was used to compare the two conditions.Results : The signal power in attention condition was significantly higher than inattention condition (P-value < 0.01). The power of alpha band in attention condition was significantly higher than inattention condition. Also, the power of beta band in attention condition was significantly more than inattention condition. Studying the different parts of brain indicated that the power in posterior regions near to visual cortex was significantly higher than anterior areas (P-value<0.01).Conclusion : : The results indicated an increased signal power in attention condition. Moreover, power in posterior regions is more than anterior regions which is in accordance with the fact that brain visual cortex is placed in posterior parts of the brain and the visual stimulus may activate those regions more than the other parts.

کلیدواژه ها:

Brain Computer Interface (BCI) ، Electroencephalogram (EEG) Signal ، Steady State Visually Evoked Potential (SSVEP) ، Biological Signal Processing ، Attention