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Rapid Communication with a "P300" Matrix Speller Using Electrocorticographic Signals (ECoG).

Brunner P, Ritaccio AL, Emrich JF, Bischof H, Schalk G - Front Neurosci (2011)

Bottom Line: The results showed that the subject sustained a rate of 17 characters/min (i.e., 69 bits/min), and achieved a peak rate of 22 characters/min (i.e., 113 bits/min).Detailed analysis of the results suggests that ERPs over visual areas (i.e., visual evoked potentials) contribute significantly to the performance of the matrix speller BCI system.Thus, with additional verification in more subjects, these results may further extend the communication options for people with serious neuromuscular disabilities.

View Article: PubMed Central - PubMed

Affiliation: New York State Department of Health, Brain-Computer Interface Research and Development Program, Wadsworth Center Albany, NY, USA.

ABSTRACT
A brain-computer interface (BCI) can provide a non-muscular communication channel to severely disabled people. One particular realization of a BCI is the P300 matrix speller that was originally described by Farwell and Donchin (1988). This speller uses event-related potentials (ERPs) that include the P300 ERP. All previous online studies of the P300 matrix speller used scalp-recorded electroencephalography (EEG) and were limited in their communication performance to only a few characters per minute. In our study, we investigated the feasibility of using electrocorticographic (ECoG) signals for online operation of the matrix speller, and determined associated spelling rates. We used the matrix speller that is implemented in the BCI2000 system. This speller used ECoG signals that were recorded from frontal, parietal, and occipital areas in one subject. This subject spelled a total of 444 characters in online experiments. The results showed that the subject sustained a rate of 17 characters/min (i.e., 69 bits/min), and achieved a peak rate of 22 characters/min (i.e., 113 bits/min). Detailed analysis of the results suggests that ERPs over visual areas (i.e., visual evoked potentials) contribute significantly to the performance of the matrix speller BCI system. Our results also point to potential reasons for the apparent advantages in spelling performance of ECoG compared to EEG. Thus, with additional verification in more subjects, these results may further extend the communication options for people with serious neuromuscular disabilities.

No MeSH data available.


Experimental setup. The subject sat 60 cm in front of a flat-screen monitor that presented a centered 6 × 6 matrix containing alphanumeric characters as well as space (Sp) and backspace (Bs). The rows and columns in the matrix flashed rapidly and pseudo-randomly. The subject's task was to pay attention to the intended character. The computer determined the intended character from the subject's ECoG responses.
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Figure 2: Experimental setup. The subject sat 60 cm in front of a flat-screen monitor that presented a centered 6 × 6 matrix containing alphanumeric characters as well as space (Sp) and backspace (Bs). The rows and columns in the matrix flashed rapidly and pseudo-randomly. The subject's task was to pay attention to the intended character. The computer determined the intended character from the subject's ECoG responses.

Mentions: The subject sat 60 cm in front of a flat-screen monitor. She was presented with a matrix of alphanumeric characters that was centered on the screen and arranged in a 6 × 6 configuration (see Figure 2). At this distance, the matrix subtended ±7.1° of the horizontal and vertical visual field.


Rapid Communication with a "P300" Matrix Speller Using Electrocorticographic Signals (ECoG).

Brunner P, Ritaccio AL, Emrich JF, Bischof H, Schalk G - Front Neurosci (2011)

Experimental setup. The subject sat 60 cm in front of a flat-screen monitor that presented a centered 6 × 6 matrix containing alphanumeric characters as well as space (Sp) and backspace (Bs). The rows and columns in the matrix flashed rapidly and pseudo-randomly. The subject's task was to pay attention to the intended character. The computer determined the intended character from the subject's ECoG responses.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3037528&req=5

Figure 2: Experimental setup. The subject sat 60 cm in front of a flat-screen monitor that presented a centered 6 × 6 matrix containing alphanumeric characters as well as space (Sp) and backspace (Bs). The rows and columns in the matrix flashed rapidly and pseudo-randomly. The subject's task was to pay attention to the intended character. The computer determined the intended character from the subject's ECoG responses.
Mentions: The subject sat 60 cm in front of a flat-screen monitor. She was presented with a matrix of alphanumeric characters that was centered on the screen and arranged in a 6 × 6 configuration (see Figure 2). At this distance, the matrix subtended ±7.1° of the horizontal and vertical visual field.

Bottom Line: The results showed that the subject sustained a rate of 17 characters/min (i.e., 69 bits/min), and achieved a peak rate of 22 characters/min (i.e., 113 bits/min).Detailed analysis of the results suggests that ERPs over visual areas (i.e., visual evoked potentials) contribute significantly to the performance of the matrix speller BCI system.Thus, with additional verification in more subjects, these results may further extend the communication options for people with serious neuromuscular disabilities.

View Article: PubMed Central - PubMed

Affiliation: New York State Department of Health, Brain-Computer Interface Research and Development Program, Wadsworth Center Albany, NY, USA.

ABSTRACT
A brain-computer interface (BCI) can provide a non-muscular communication channel to severely disabled people. One particular realization of a BCI is the P300 matrix speller that was originally described by Farwell and Donchin (1988). This speller uses event-related potentials (ERPs) that include the P300 ERP. All previous online studies of the P300 matrix speller used scalp-recorded electroencephalography (EEG) and were limited in their communication performance to only a few characters per minute. In our study, we investigated the feasibility of using electrocorticographic (ECoG) signals for online operation of the matrix speller, and determined associated spelling rates. We used the matrix speller that is implemented in the BCI2000 system. This speller used ECoG signals that were recorded from frontal, parietal, and occipital areas in one subject. This subject spelled a total of 444 characters in online experiments. The results showed that the subject sustained a rate of 17 characters/min (i.e., 69 bits/min), and achieved a peak rate of 22 characters/min (i.e., 113 bits/min). Detailed analysis of the results suggests that ERPs over visual areas (i.e., visual evoked potentials) contribute significantly to the performance of the matrix speller BCI system. Our results also point to potential reasons for the apparent advantages in spelling performance of ECoG compared to EEG. Thus, with additional verification in more subjects, these results may further extend the communication options for people with serious neuromuscular disabilities.

No MeSH data available.