%0 Journal Article %J IEEE Trans Neural Syst Rehabil Eng %D 2014 %T Adaptive spatio-temporal filtering for movement related potentials in EEG-based brain-computer interfaces. %A Lu, Jun %A Xie, Kan %A Dennis J. McFarland %K Algorithms %K Artificial Intelligence %K brain-computer interfaces %K Data Interpretation, Statistical %K Electroencephalography %K Evoked Potentials, Motor %K Humans %K Imagination %K Motor Cortex %K Movement %K Pattern Recognition, Automated %K Reproducibility of Results %K Sensitivity and Specificity %K Signal Processing, Computer-Assisted %K Spatio-Temporal Analysis %X Movement related potentials (MRPs) are used as features in many brain-computer interfaces (BCIs) based on electroencephalogram (EEG). MRP feature extraction is challenging since EEG is noisy and varies between subjects. Previous studies used spatial and spatio-temporal filtering methods to deal with these problems. However, they did not optimize temporal information or may have been susceptible to overfitting when training data are limited and the feature space is of high dimension. Furthermore, most of these studies manually select data windows and low-pass frequencies. We propose an adaptive spatio-temporal (AST) filtering method to model MRPs more accurately in lower dimensional space. AST automatically optimizes all parameters by employing a Gaussian kernel to construct a low-pass time-frequency filter and a linear ridge regression (LRR) algorithm to compute a spatial filter. Optimal parameters are simultaneously sought by minimizing leave-one-out cross-validation error through gradient descent. Using four BCI datasets from 12 individuals, we compare the performances of AST filter to two popular methods: the discriminant spatial pattern filter and regularized spatio-temporal filter. The results demonstrate that our AST filter can make more accurate predictions and is computationally feasible. %B IEEE Trans Neural Syst Rehabil Eng %V 22 %P 847-57 %8 07/2014 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/24723632 %N 4 %R 10.1109/TNSRE.2014.2315717 %0 Journal Article %J Amyotroph Lateral Scler Frontotemporal Degener %D 2014 %T Brain-computer interface (BCI) evaluation in people with amyotrophic lateral sclerosis. %A McCane, Lynn M %A Sellers, Eric W %A Dennis J. McFarland %A Mak, Joseph N %A Carmack, C Steve %A Zeitlin, Debra %A Jonathan Wolpaw %A Theresa M Vaughan %K Adult %K Aged %K Amyotrophic Lateral Sclerosis %K Biofeedback, Psychology %K brain-computer interfaces %K Communication Disorders %K Electroencephalography %K Event-Related Potentials, P300 %K Female %K Humans %K Male %K Middle Aged %K Online Systems %K Photic Stimulation %K Psychomotor Performance %K Reaction Time %X Brain-computer interfaces (BCIs) might restore communication to people severely disabled by amyotrophic lateral sclerosis (ALS) or other disorders. We sought to: 1) define a protocol for determining whether a person with ALS can use a visual P300-based BCI; 2) determine what proportion of this population can use the BCI; and 3) identify factors affecting BCI performance. Twenty-five individuals with ALS completed an evaluation protocol using a standard 6 × 6 matrix and parameters selected by stepwise linear discrimination. With an 8-channel EEG montage, the subjects fell into two groups in BCI accuracy (chance accuracy 3%). Seventeen averaged 92 (± 3)% (range 71-100%), which is adequate for communication (G70 group). Eight averaged 12 (± 6)% (range 0-36%), inadequate for communication (L40 subject group). Performance did not correlate with disability: 11/17 (65%) of G70 subjects were severely disabled (i.e. ALSFRS-R < 5). All L40 subjects had visual impairments (e.g. nystagmus, diplopia, ptosis). P300 was larger and more anterior in G70 subjects. A 16-channel montage did not significantly improve accuracy. In conclusion, most people severely disabled by ALS could use a visual P300-based BCI for communication. In those who could not, visual impairment was the principal obstacle. For these individuals, auditory P300-based BCIs might be effective. %B Amyotroph Lateral Scler Frontotemporal Degener %V 15 %P 207-15 %8 06/2014 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/24555843 %N 3-4 %R 10.3109/21678421.2013.865750