P300-based brain-computer interface (BCI) event-related potentials (ERPs): People with amyotrophic lateral sclerosis (ALS) vs. age-matched controls.

OBJECTIVE: Brain-computer interfaces (BCIs) aimed at restoring communication to people with severe neuromuscular disabilities often use event-related potentials (ERPs) in scalp-recorded EEG activity. Up to the present, most research and development in this area has been done in the laboratory with young healthy control subjects. In order to facilitate the development of BCI most useful to people with disabilities, the present study set out to: (1) determine whether people with amyotrophic lateral sclerosis (ALS) and healthy, age-matched volunteers (HVs) differ in the speed and accuracy of their ERP-based BCI use; (2) compare the ERP characteristics of these two groups; and (3) identify ERP-related factors that might enable improvement in BCI performance for people with disabilities. METHODS: Sixteen EEG channels were recorded while people with ALS or healthy age-matched volunteers (HVs) used a P300-based BCI. The subjects with ALS had little or no remaining useful motor control (mean ALS Functional Rating Scale-Revised 9.4 (±9.5SD) (range 0-25)). Each subject attended to a target item as the items in a 6×6 visual matrix flashed. The BCI used a stepwise linear discriminant function (SWLDA) to determine the item the user wished to select (i.e., the target item). Offline analyses assessed the latencies, amplitudes, and locations of ERPs to the target and non-target items for people with ALS and age-matched control subjects. RESULTS: BCI accuracy and communication rate did not differ significantly between ALS users and HVs. Although ERP morphology was similar for the two groups, their target ERPs differed significantly in the location and amplitude of the late positivity (P300), the amplitude of the early negativity (N200), and the latency of the late negativity (LN). CONCLUSIONS: The differences in target ERP components between people with ALS and age-matched HVs are consistent with the growing recognition that ALS may affect cortical function. The development of BCIs for use by this population may begin with studies in HVs but also needs to include studies in people with ALS. Their differences in ERP components may affect the selection of electrode montages, and might also affect the selection of presentation parameters (e.g., matrix design, stimulation rate). SIGNIFICANCE: P300-based BCI performance in people severely disabled by ALS is similar to that of age-matched control subjects. At the same time, their ERP components differ to some degree from those of controls. Attention to these differences could contribute to the development of BCIs useful to those with ALS and possibly to others with severe neuromuscular disabilities.

Implementation of the National Breast and Cervical Cancer Early Detection Program: the beginning.

In 1990, Congress passed the Breast and Cervical Cancer Mortality Prevention Act because of increases in the number of low-income and uninsured women being diagnosed with breast cancer. This act authorized the Centers for Disease Control and Prevention (CDC) to establish the National Breast and Cervical Cancer Early Detection Program (NBCCEDP) to provide high-quality and timely breast and cervical cancer screening and diagnostic services to low-income, uninsured women. The program started in 1991, and, in 1993, Congress amended the act to allow the CDC to fund American Indian and Alaska Native tribes and tribal organizations. By 1996, the program was providing cancer screening across the United States. To ensure appropriate delivery and monitoring of services, the program adopted detailed policies on program management, evidence-based guidelines for clinical services, a systematized clinical data system to track service quality, and key partnerships that expand the program's reach. The NBCCEDP currently funds 67 programs, including all 50 states, the District of Columbia, 5 US territories, and 11 tribes or tribal organizations.

A general P300 brain-computer interface presentation paradigm based on performance guided constraints.

An electroencephalographic-based brain-computer interface (BCI) can provide a non-muscular method of communication. A general model for P300-based BCI stimulus presentations is introduced--the "m choose n" or C(m (number of flashes per sequence), n (number of flashes per item)) paradigm, which is a universal extension of the previously reported checkerboard paradigm (CBP). C(m,n) captures all possible (unconstrained) ways to flash target items, and then applies constraints to enhance ERP's produced by attended matrix items. We explore a C(36,5) instance of C(m,n) called the "five flash paradigm" (FFP) and compare its performance to the CBP. Eight subjects were tested in each paradigm, counter-balanced. Twelve minutes of calibration data were used as input to a stepwise linear discriminant analysis to derive classification coefficients used for online classification. Accuracy was consistently high for FFP (88%) and CBP (90%); information transfer rate was significantly higher for the FFP (63 bpm) than the CBP (48 bpm). The C(m,n) is a novel and effective general strategy for organizing stimulus groups. Appropriate choices for "m," "n," and specific constraints can improve presentation paradigms by adjusting the parameters in a subject specific manner. This may be especially important for people with neuromuscular disabilities.

Surveillance of demographic characteristics and health behaviors among adult cancer survivors--Behavioral Risk Factor Surveillance System, United States, 2009.

PROBLEM/CONDITION: Approximately 12 million people are living with cancer in the United States. Limited information is available on national and state assessments of health behaviors among cancer survivors. Using data from the Behavioral Risk Factor Surveillance System (BRFSS), this report provides a descriptive state-level assessment of demographic characteristics and health behaviors among cancer survivors aged ≥18 years. REPORTING PERIOD COVERED: 2009 DESCRIPTION OF SYSTEM: BRFSS is an ongoing, state-based, random-digit-dialed telephone survey of the noninstitutionalized U.S. population aged ≥18 years. BRFSS collects information on health risk behaviors and use of preventive health services related to leading causes of death and morbidity. In 2009, BRFSS added questions about previous cancer diagnoses to the core module. The 2009 BRFSS also included an optional cancer survivorship module that assessed cancer treatment history and health insurance coverage for cancer survivors. In 2009, all 50 states, the District of Columbia, Guam, Puerto Rico, and the U.S. Virgin Islands administered the core cancer survivorship questions, and 10 states administered the optional supplemental cancer survivorship module. Five states added questions on mammography and Papanicolaou (Pap) test use, eight states included questions on colorectal screening, and five states included questions on prostate cancer screening. RESULTS: An estimated 7.2% of the U.S. general population aged ≥18 years reported having received a previous cancer diagnosis (excluding nonmelanoma skin cancer). A total of 78.8% of cancer survivors were aged ≥50 years, and 39.2% had received a diagnosis of cancer >10 years previously. A total of 57.8% reported receiving an influenza vaccination during the previous year, and 48.3% reported ever receiving a pneumococcal vaccination. At the time of the interview, 6.8% of cancer survivors had no health insurance, and 12% had been denied health insurance, life insurance, or both because of their cancer diagnosis. The prevalence of cardiovascular disease was higher among male cancer survivors (23.4%) than female cancer survivors (14.3%), as was the prevalence of diabetes (19.6% and 14.7%, respectively). Overall, approximately 15.1% of cancer survivors were current cigarette smokers, 27.5% were obese, and 31.5% had not engaged in any leisure-time physical activity during the past 30 days. Demographic characteristics and health behaviors among cancer survivors varied substantially by state. INTERPRETATION: Health behaviors and preventive health care practices among cancer survivors vary by state and demographic characteristics. A large proportion of cancer survivors have comorbid conditions, currently smoke, do not participate in any leisure-time physical activity, and are obese. In addition, many are not receiving recommended preventive care, including cancer screening and influenza and pneumococcal vaccinations. PUBLIC HEALTH ACTION: Health-care providers and patients should be aware of the importance of preventive care, smoking cessation, regular physical activity, and maintaining a healthy weight for cancer survivors. The findings in this report can help public health practitioners, researchers, and comprehensive cancer control programs evaluate the effectiveness of program activities for cancer survivors, assess the needs of cancer survivors at the state level, and allocate appropriate resources to address those needs.

The P300-based brain-computer interface (BCI): effects of stimulus rate.

OBJECTIVE: Brain-computer interface technology can restore communication and control to people who are severely paralyzed. We have developed a non-invasive BCI based on the P300 event-related potential that uses an 8×9 matrix of 72 items that flash in groups of 6. Stimulus presentation rate (i.e., flash rate) is one of several parameters that could affect the speed and accuracy of performance. We studied performance (i.e., accuracy and characters/min) on copy spelling as a function of flash rate. METHODS: In the first study of six BCI users, stimulus-on and stimulus-off times were equal and flash rate was 4, 8, 16, or 32 Hz. In the second study of five BCI users, flash rate was varied by changing either the stimulus-on or stimulus-off time. RESULTS: For all users, lower flash rates gave higher accuracy. The flash rate that gave the highest characters/min varied across users, ranging from 8 to 32 Hz. However, variations in stimulus-on and stimulus-off times did not themselves significantly affect accuracy. Providing feedback did not affect results in either study suggesting that offline analyses should readily generalize to online performance. However there do appear to be session-specific effects that can influence the generalizability of classifier results. CONCLUSIONS: The results show that stimulus presentation (i.e., flash) rate affects the accuracy and speed of P300 BCI performance. SIGNIFICANCE: These results extend the range over which slower flash rates increase the amplitude of the P300. Considering also presentation time, the optimal rate differs among users, and thus should be set empirically for each user. Optimal flash rate might also vary with other parameters such as the number of items in the matrix.

A comparison of common spatial patterns with complex band power features in a four-class BCI experiment.

We report on the offline analysis of four-class brain-computer interface (BCI) data recordings. Although the analysis is done within defined time windows (cue-based BCI), our goal is to work toward an approach which classifies on-going electroencephalogram (EEG) signals without the use of such windows (un-cued BCI). To that end, we provide some elements of that analysis related to timing issues that will become important as we pursue this goal in the future. A new set of features called complex band power (CBP) features which make explicit use of phase are introduced and are shown to produce good results. As reference methods we used traditional band power features and the method of common spatial patterns. We consider also for the first time in the context of a four-class problem the issue of variability of the features over time and how much data is required to give good classification results. We do this in a practical way where training data precedes testing data in time.

Continuous EEG classification during motor imagery--simulation of an asynchronous BCI.

Nearly all electroencephalogram (EEG)-based brain-computer interface (BCI) systems operate in a cue-paced or synchronous mode. This means that the onset of mental activity (thought) is externally-paced and the EEG has to be analyzed in predefined time windows. In the near future, BCI systems that allow the user to intend a specific mental pattern whenever she/he wishes to produce such patterns will also become important. An asynchronous BCI is characterized by continuous analyzing and classification of EEG data. Therefore, it is important to maximize the hits (true positive rate) during an intended mental task and to minimize the false positive detections in the resting or idling state. EEG data recorded during right/left motor imagery is used to simulate an asynchronous BCI. To optimize the classification results, a refractory period and a dwell time are introduced.

Recording and marking with silicon multichannel electrodes.

This protocol describes an implementation of recording and analysis of evoked potentials in the hippocampal cortex, combined with lesioning using multichannel silicon probes. Multichannel recording offers the advantage of capturing a potential field at one instant in time. The potentials are then subjected to current source density (CSD) analysis, to reveal the layer-by-layer current sources and sinks. Signals from each channel of a silicon probe (maximum 16 channels in this study) were amplified and digitized at up to 40 kHz after sample-and-hold circuits. A modular lesion circuit board could be inserted between the input preamplifiers and the silicon probe, such that any one of the 16 electrodes could be connected to a DC lesion current. By making a lesion at the electrode showing a physiological event of interest, the anatomical location of the event can be precisely identified, as shown for the distal dendritic current sink in CA1 following medial perforant path stimulation. Making two discrete lesions through the silicon probe is useful to indicate the degree of tissue shrinkage during histological procedures. In addition, potential/CSD profiles were stable following small movements of the silicon probe, suggesting that the probe did not cause excessive damage to the brain.