In the field of BCI systems development, an important issue is to determine if a BCI device can work effectively using different presentation modalities, since possible users may have auditory or visual deficiencies. Previous research has shown that both auditory and visual oddball tasks elicit large P300 responses (Squires et al. 1977; Duncan-Johnson and Donchin 1982; Fabiani et al. 1987). In addition, McDonald et al.(2000) and Teder-Salejarvi et al. (2002) reported higher accuracy and larger ERP amplitude when auditory and visual stimuli were presented simultaneously, than when either modality was presented by itself. Farewell and Donchin (1988) first used P300 Inhibitors,research,lifescience,medical to select items displayed on a computer

monitor, by presenting participants with a 6 × 6 matrix, Inhibitors,research,lifescience,medical with each of the 36 cells containing one character. Participants were asked to pay attention to one of those cells, while the matrix rows and columns flashed in random order. In one trial of 12 possible flashed lines (six rows and six columns), the target cell flashes only twice: once in a column and once in a row. These two rare events typically elicit a

P300 response. This example of oddball paradigm has been employed in order to build Inhibitors,research,lifescience,medical a P300 speller system, allowing users to communicate by mean of EEG recording. A main issue of visual P300 is the use in subjects that suffer from visual impairments. In fact, users are required to fixate the matrix cell on the screen and to concentrate on itFor such Inhibitors,research,lifescience,medical reason, a preserved visual attention is supposed to be necessary in order to use P300 BCI. Treder and Blankertz (2010) investigated if a good performance at BCI depends on eye movements control (i.e., overt attention) or whether it is also possible with targets in the visual periphery (covert attention). They found that ERP-based BCI can be driven in both modes Inhibitors,research,lifescience,medical of attention, but the performance was significantly better for overt attention. The authors suggest the importance of developing innovative Verteporfin clinical trial spellers that are reliably based on peripheral vision, since most of ALS patients

show impaired eye movements. Also Brunner et al. (2010) explored this issue and found that the accuracy of P300 speller is affected by gaze direction, so its clinical applicability in ALS patients with impaired gaze may be limited. In such cases, auditory stimuli could be more suitable. The auditory version of the oddball Phosphatidylinositol diacylglycerol-lyase tasks uses two different tones and an interstimuli interval of a few seconds, with the target stimulus occurring less frequently than the standard stimulus. As in the classic visual paradigm, the subject is required to distinguish between the two tones by responding to the target with a covert or overt response. Only few studies have employed auditory oddball to elicit particular event-related potentials with P300 BCIs systems (see, for example, Hill et al. 2006; Sellers and Donchin 2006; Furdea et al. 2009; Klobassa et al. 2009). Hill et al.