With the limitations described
below, its use is possible with patients suffering from impairment in oculomotor dysfunctions, such as ALS and locked-in patients. Besides, a P300-based BCI does not require initial user training in order to generate a P300 in response to the desired target. In a recent study, Guger et al. (2009) proved that the P300-based BCI can achieve high accuracy after only Inhibitors,research,lifescience,medical 5 min of training. In such study, 72.8% of the subjects reached 100% accuracy with a row-column paradigm speller. Interestingly, they found that the system was more accurate for people who slept less the previous night, while no significant differences were observed with regard to gender, level of education, working duration, and cigarette and coffee consumption. These results overcome those
obtained in a previous study by Guger et al. (2003), where they tested a motor imagery-based Inhibitors,research,lifescience,medical BCI system and found that, after 20–30 min (two sessions) of training, about 93% of the subjects were able to achieve classification accuracy above 60%. These findings highlights that P300-based BCIs are a far more practical choice than SMR-based BCIs. In P300-BCIs, P300 ERPs Inhibitors,research,lifescience,medical from several trials are averaged, in order to improve accuracy and reduce noise. The classifier discriminates which stimuli elicit a robust P300. If none of the stimuli provoke an ERP different from other ERPs, this indicates that it is not possible to use P300 for communicating. Such phenomenon has been observed across different BCI approaches, with 20% of subjects being not proficient in using BCI, and it has been called “BCI Inhibitors,research,lifescience,medical illiteracy” (Kubler and Muller 2007). The main explanation of such phenomenon is that not every person can generate the brain activity necessary to control a specific BCI. In fact, even if all people’s brain shares (more or less) the same functional properties and subdivisions, some differences in brain structure can be present. Inhibitors,research,lifescience,medical For
example, some users produce P300 evoked-related potential not detectable at the level of the scalp, so that EEG cannot be effectively performed. In particular, it has been only observed that 10% of healthy subjects do not produce a robust P300. Some issues must be considered while planning to use a P300-BCI system. Two important criteria in order to evaluate the feasibility of a BCI system are the speed and the accuracy (Kubler et al. 2001a). The former is related to the fact that the more rapidly a BCI can be controlled, the more amount of information can be SB939 concentration produced by the user, and the faster communication is possible. Obviously, compared to speech, the communication rate is reduced with BCI, but a limit presumably exists, below which the communication rate of a BCI should not fall.