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As the brain ages, it suffers several neurochemical, structural and functional changes. These deficits are primarily reflected on daily memory tasks. In the present work, we use the Wisconsin Card Sorting Task (WCST) task to assess P300 component of the event-related potential (ERP) as a marker for aging. Considering age-related effects, WCST was applied to young, middle-aged and elder participants...
Electroencephalogram (EEG) Ambulatory monitoring has been regarded as a promising tool to improve diagnosis, classification and medication prescription in patients with epilepsy and other paroxysmal diseases. This study presents the development of a wireless and wearable EEG acquisition system for ambulatory monitoring. The platform comprises 32 active dry electrodes, an analog-to-digital conversion...
This paper presents the development of an integration technology that offers a breakthrough solution for the industrial manufacturing of flexible smart materials with optical sensing features. Subsequently, it aims the development of a flexible substrate, or foil, in which optical waveguides and sensing elements are integrated in line during the manufacturing process of the substrate itself. This...
Biopotential recording electrodes have been used to monitor non-invasively electroencephalogram (EEG), electromyogram (EMG) and electrocardiogram (ECG) by means of electrolyte pastes that improve electrode-skin interface. However, the skin preparation of 32 EEG electrodes may take up to 45 min. Despite the low skin-contact impedance and reasonable stability of the standard Ag/AgCl electrodes, several...
What is the optimal number of electrodes one can use in discrimination of tasks for a brain computer interface (BCI)? To address this question, the number and location of scalp electrodes in the acquisition of human electroencephalography (EEG) and discrimination of motor imagery tasks were optimized by using a systematic optimization approach. The systematic analysis results in the most reliable...
Brain-computer interfaces (BCI) based on event related potentials (ERP) have been successfully developed for applications like virtual spellers and navigation systems. This study tests the use of visual stimuli unbalanced in the subject's field of view to simultaneously cue mental imagery tasks (left vs. right hand movement) and detect subject attention. The responses to unbalanced cues were compared...
Many brain computer interfaces (BCI) are based on feature selection from electroencephalogram (EEG) signals. To acquire these signals, a set of electrodes is used, most of the times attached to a brain cap. Several brain cap designs have been presented, as well many different electrodes. So far, all the brain caps are difficult and uncomfortable to wear. Moreover, the electrodes, wet or dry, are also...
Current non-invasive brain-computer interface (BCI) designs use as much electroencephalogram (EEG) features as possible rather than few well known motor-reactive features (e.g. rolandic mu-rhythm picked from C3 and C4 channels). Additionally, motor-reactive rhythms do not provide BCI control for every subject. Thus, a subject-specific feature set needs to be determined from a large feature space....
This paper presents a solution for electrode localization in a body-area network using a low-frequency microantenna and a localization algorithm. Electrode positioning is a common issue in any physiological experiment. Although wireless node localization is a topic under active research, a precise method with few centimetres of range and a resolution in the order of millimetres is still to be found,...
The aim of this study is to compare 2 EEG pattern classification methods towards the development of BCI. The methods are: (1) discriminant stepwise, and (2) principal component analysis (PCA) - linear discriminant analysis (LDA) joint method. Both methods use Fisher's LDA approach, but differ in the data dimensionality reduction procedure. Data were recorded from 3 male subjects 20-30 years old. Three...
Brain-computer interfaces (BCI) promise to be a very important tool for the handicapped people in the near future. A wireless biopotential acquisition system is proposed as a solution for true mobility during non-invasive BCI operation. Special care about noise must be taken in a signal acquisition system for biopotentials. The EEG signal amplitude ranges from a few to dozens of micro-volts and it...
This paper presents a study about the amplitude, latency and distribution of P300 in twelve healthy volunteers (5 women and 7 men, aged between 19-70, with a mean of 35.5 years) that were submitted to two Novelty Oddball Paradigms. The difference between them is on stimulus modalities, which are visual and auditory. Usually, a P300-based brain computer interface has visual stimuli but we are also...
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