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Eyes-open and eyes-closed are two widely accepted resting conditions in neuroimaging study. When alternating between the two conditions, electroencephalogram (EEG) studies have reported the modulation of alpha band (8-12 Hz) oscillation. Functional magnetic resonance imaging (fMRI) studies have found modulation of blood-oxygen-level dependent (BOLD) response. The neuronal correlates of the two modulations...
Tripolar electrodes have been shown to have less mutual information and higher spatial resolution than disc electrodes. In this work, a four-layer anisotropic concentric spherical head computer model was programmed, then four configurations of time-varying dipole signals were used to generate the scalp surface signals that would be obtained with tripolar and disc electrodes, and four important EEG...
An efficient alternative channel for communication without overt speech and hand movements is important to increase the quality of life for patients suffering from Amiotrophic Lateral Sclerosis or other illnesses that prevent correct limb and facial muscular responses. Often, such diseases leave the ocular movements preserved for a relatively long time. The aim of this study is to present a new approach...
In the present study, somatosensory evoked potentials following contact cold painful stimulation of the posterior tibial nerve (PTN) at left and right ankle were investigated in 4 normal subjects. By fitting dipole models to independent components, more sources were found in pain status than in non pain condition. Among these fitted components, three SEPs related components and one pain related component...
Sleep staging is one of the most important tasks on the context of sleep studies. From more than 40 years the gold standard to the characterization of patient's sleep is the use of the rules proposed by Rechtschaffen and Kales (R&K). However this method has the limitation of the unnatural assignment of discrete stages instead of doing it in a continuous manner. As part of a more general framework,...
This study analyses the spectral components of the heart rate fluctuations of a new contact-less technology for sleep evaluation. Both heart beat interval (HBI) and movement activity were extracted from the multichannel ballistocardiographic (BCG) measurements, based on Emfit sensor foils placed into bed mattress. Powers spectral densities (PSD) of HBI have been compared with the ones obtained from...
In this paper we assess a dependency measure for multivariate time series termed extrinsic-to-intrinsic-power-ratio (EIPR) using two different signal models. In a comparison with partial directed coherence (PDC) we show that both measures correctly identify imposed couplings, but that limitations of the PDC do not affect EIPR. Moreover, EIPR is successfully used for the localization of the seizure...
We describe a novel algorithm for the prediction of epileptic seizures using scalp EEG. The method is based on the analysis of the positive zero-crossing interval series of the EEG signal and its first and second derivatives as a measure of brain dynamics. In a moving-window analysis, we estimated the probability density of these intervals and computed the differential entropy. The resultant entropy...
We present a digital system for adaptive data compression for low power wireless transmission of Electroencephalography (EEG) data. The proposed system acts as a base-band processor between the EEG analog-to-digital front-end and RF transceiver. It performs a real-time accuracy energy trade-off for multi-channel EEG signal transmission by controlling the volume of transmitted data. We propose a multi-core...
Brain is a complex network optimized both for segregated and distributed information processing. To perform cognitive tasks, different areas of the brain must ldquocooperate,rdquo thereby forming complex networks of interactions also known as brain functional networks. Previous studies have shown that these networks exhibit ldquosmall-worldrdquo characteristics. Small-world topology, however, is a...
In this paper, we use EEG signals to classify two emotions-happiness and sadness. These emotions are evoked by showing subjects pictures of smile and cry facial expressions. We propose a frequency band searching method to choose an optimal band into which the recorded EEG signal is filtered. We use common spatial patterns (CSP) and linear-SVM to classify these two emotions. To investigate the time...
Non-invasive EEG-based motor imagery brain-computer interface (MI-BCI) holds promise to effectively restore motor control to stroke survivors. This clinical study investigates the effects of MI-BCI for upper limb robotic rehabilitation compared to standard robotic rehabilitation. The subjects are hemiparetic stroke patients with mean age of 50.2 and baseline Fugl-Meyer (FM) score 29.7 (out of 66,...
In neurophysiology, it is important to determine the causal relationships between neuronal sites. The major problem with existing methods for quantifying the causality in the brain, e.g. Granger causality, is that they assume an multi-variate autoregressive signal model for the multi-channel EEG signals and do not take the nonlinear dependencies between neuronal oscillations into account. In this...
Animal models are used extensively in basic epilepsy research. In many studies, there is a need to accurately score and quantify all epileptic spike and wave discharges (SWDs) as captured by electroencephalographic (EEG) recordings. Manual scoring of long term EEG recordings is a time-consuming and tedious task that requires inordinate amount of time of laboratory personnel and an experienced electroencephalographer...
Seizure onset prediction in epilepsy is a challenge which is under investigation using many and varied signal processing techniques. Here we present a multi-stage phase synchrony based system that brings to bear the advantages of many techniques in each substage. The 1st stage of the system unmixes continuous long-term (2-4 days) multichannel scalp EEG using spatially constrained Independent Component...
Several markers based on quantitative electroencephalogram (qEEG) analysis have been associated with the neuroprotective effects of therapeutic hypothermia on hypoxic-ischemic encephalopathy (HIE) after cardiac arrest (CA). Nevertheless, the makers by far have not been linked to the temporal process of the ischemic neuronal death. In this study, we investigated the long-range correlations in EEG power...
Previous research has shown that a characteristic burst-suppression (BS) pattern appears in EEG during the early recovery period following cardiac arrest (CA). To study cortical and subcortical neural activity underlying BS, extracellular activity in the parietal cortex and the centromedian nucleus of the thalamus and extradural EEG were recorded in a rodent CA model. Preliminary results show that...
Many epilepsy patients cannot call for help during a seizure, because they are unconscious or because of the affection of their motor system or speech function. This can lead to injuries, medical complications and at worst death. An alarm system setting off at seizure onset could help to avoid hazards. Today no reliable alarm systems are available. A Multi-modal Intelligent Seizure Acquisition (MISA)...
This paper evaluates supervised and unsupervised adaptive schemes applied to online support vector machine (SVM) that classifies BCI data. Online SVM processes fresh samples as they come and update existing support vectors without referring to pervious samples. It is shown that the performance of online SVM is similar to that of the standard SVM, and both supervised and unsupervised schemes improve...
The human rewards network is a complex system spanning both cortical and subcortical regions. While much is known about the functions of the various components of the network, research on the behavior of the network as a whole has been stymied due to an inability to detect signals at a high enough temporal resolution from both superficial and deep network components simultaneously. In this paper,...
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