Real Time FMRI Avoiding Drift Using Answer Blocks

Thomas WJ Ash¹, T Adrian Carpenter¹, Guy B. Williams¹

Where real time fMRI needs solely a digital (e.g., task vs rest or task 1 vs task 2) output, answer blocks can provide a means of circumventing the drift that is known to affect results. Using answer blocks, we improve performance compared to averaging over a block using classifiers from 53% to 84%, and using ROI techniques from 53% to 64%. This also gives a means for presenting probabilistic outputs to class membership, which are vital when dealing with impaired patients, for whom this kind of technique may be their only communication channel.