Evaluating brain-computer interface performance using color in the P300 checkerboard speller.

OBJECTIVE: Current Brain-Computer Interface (BCI) systems typically flash an array of items from grey to white (GW). The objective of this study was to evaluate BCI performance using uniquely colored stimuli. METHODS: In addition to the GW stimuli, the current study tested two types of color stimuli (grey to color [GC] and color intensification [CI]). The main hypotheses were that in a checkboard paradigm, unique color stimuli will: (1) increase BCI performance over the standard GW paradigm; (2) elicit larger event-related potentials (ERPs); and, (3) improve offline performance with an electrode selection algorithm (i.e., Jumpwise). RESULTS: Online results (n=36) showed that GC provides higher accuracy and information transfer rate than the CI and GW conditions. Waveform analysis showed that GC produced higher amplitude ERPs than CI and GW. Information transfer rate was improved by the Jumpwise-selected channel locations in all conditions. CONCLUSIONS: Unique color stimuli (GC) improved BCI performance and enhanced ERPs. Jumpwise-selected electrode locations improved offline performance. SIGNIFICANCE: These results show that in a checkerboard paradigm, unique color stimuli increase BCI performance, are preferred by participants, and are important to the design of end-user applications; thus, could lead to an increase in end-user performance and acceptance of BCI technology.

Increasing BCI communication rates with dynamic stopping towards more practical use: an ALS study.

OBJECTIVE: The P300 speller is a brain-computer interface (BCI) that can possibly restore communication abilities to individuals with severe neuromuscular disabilities, such as amyotrophic lateral sclerosis (ALS), by exploiting elicited brain signals in electroencephalography (EEG) data. However, accurate spelling with BCIs is slow due to the need to average data over multiple trials to increase the signal-to-noise ratio (SNR) of the elicited brain signals. Probabilistic approaches to dynamically control data collection have shown improved performance in non-disabled populations; however, validation of these approaches in a target BCI user population has not occurred. APPROACH: We have developed a data-driven algorithm for the P300 speller based on Bayesian inference that improves spelling time by adaptively selecting the number of trials based on the acute SNR of a user's EEG data. We further enhanced the algorithm by incorporating information about the user's language. In this current study, we test and validate the algorithms online in a target BCI user population, by comparing the performance of the dynamic stopping (DS) (or early stopping) algorithms against the current state-of-the-art method, static data collection, where the amount of data collected is fixed prior to online operation. MAIN RESULTS: Results from online testing of the DS algorithms in participants with ALS demonstrate a significant increase in communication rate as measured in bits/min (100-300%), and theoretical bit rate (100-550%), while maintaining selection accuracy. Participants also overwhelmingly preferred the DS algorithms. SIGNIFICANCE: We have developed a viable BCI algorithm that has been tested in a target BCI population which has the potential for translation to improve BCI speller performance towards more practical use for communication.

Channel selection methods for the P300 Speller.

The P300 Speller brain-computer interface (BCI) allows a user to communicate without muscle activity by reading electrical signals on the scalp via electroencephalogram. Modern BCI systems use multiple electrodes ("channels") to collect data, which has been shown to improve speller accuracy; however, system cost and setup time can increase substantially with the number of channels in use, so it is in the user's interest to use a channel set of modest size. This constraint increases the importance of using an effective channel set, but current systems typically utilize the same channel montage for each user. We examine the effect of active channel selection for individuals on speller performance, using generalized standard feature-selection methods, and present a new channel selection method, termed jumpwise regression, that extends the Stepwise Linear Discriminant Analysis classifier. Simulating the selections of each method on real P300 Speller data, we obtain results demonstrating that active channel selection can improve speller accuracy for most users relative to a standard channel set, with particular benefit for users who experience low performance using the standard set. Of the methods tested, jumpwise regression offers accuracy gains similar to the best-performing feature-selection methods, and is robust enough for online use.

Abbreviated endometriosis-associated infertility correlates with in vitro fertilization success.

The utility of in vitro fertilization (IVF) for refractory infertility associated with endometriosis was studied by reviewing the 6-year experience with IVF and pregnancy follow-up at University Hospital, London, Ontario. Two hundred forty cycles were begun in 124 couples in whom endometriosis was the sole identified cause of infertility. In a program employing predominantly ultrasound-guided transvaginal oocyte retrieval, live birth rates were not reduced with advanced degrees of endometriosis. Live births were positively correlated with a shorter infertility duration.

Elevation of serum progesterone with oral micronized progesterone after in vitro fertilization. A randomized, controlled trial.

In a randomized, controlled trial, oral micronized progesterone (P4) supplementation effectively elevated luteal phase serum P4 levels after in vitro fertilization (IVF). Of 34 nonconception IVF cycles, 12 were supplemented with oral micronized P4, 200 mg four times daily, beginning the day of oocyte retrieval, while 22 control cycles did not receive supplementation. With oral micronized P4 supplementation the P4 levels were higher (P less than .001) and the luteal phase longer (P less than .05). Oral micronized P4 supplementation appears to be a convenient method of supporting serum P4 levels during the luteal phase after IVF.

Controlled versus hyperemic flow during reperfusion of jeopardized ischemic myocardium.

Controlled versus uncontrolled reperfusion of ischemic myocardium after experimental coronary artery occlusion was studied to determine the effect on regional ventricular wall motion and associated biochemical alterations. Fourteen pigs underwent coronary artery occlusion for 1 hour followed by 2 hours of reperfusion. In seven animals uncontrolled reperfusion was achieved by complete release of the arterial occlusion resulting in hyperemic flow. In seven other animals coronary flow during reperfusion was controlled at baseline levels eliminating hyperemic flow. Our results show that controlled reperfusion lessens end-diastolic wall thickness, reduces myocardial calcium deposition, increases the rate of mitochondrial oxidative phosphorylation, and preserves cellular high-energy phosphate stores in the ischemic-reperfused myocardium when compared to the uncontrolled reperfusion state. These data suggest that the magnitude of flow at an early stage of reperfusion is one of the important determinants in the outcome of ischemic myocardium.