The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Electrical stimulation on the posterior tibial nerve is commonly used in the measurement of somatosensory evoked potential (SEP). To improve the efficiency of stimulation, the potential field and current density distributions under the surface electrodes were simulated with a three layer theoretical model. The mirror method was used to analyze the potential field of point charge. Integration of the...
Invasive intracranial electroencephalography (EEG) studies help identify the epileptogenic focus and assess if the identified zone overlies eloquent cortex by means of cortical stimulation. Proper interpretation and use of the intracranial recording/stimulation studies requires an effective display of multimodal information. We developed a software system which can combine the patient's segmented...
Over the past ten years, we have tested and helped develop a multi-electrode array for chronic cortical recordings in behaving non-human primates. We have found that it is feasible to record from dozens of single units in the motor cortex for extended periods of time and that these signals can be decoded in a closed-loop, real-time system to generate goal-directed behavior of external devices. This...
Wavelet entropy (WE), a new method of complexity measure for non-stationary signals, was used to investigate the dynamic features of rat EEGs under three vigilance states. The EEGs of the freely moving rats were recorded with implanted electrodes and were decomposed into four components of delta, theta, alpha and beta by using multi-resolution wavelet transform. Then, the wavelet entropy curves were...
It has been a goal of neuroprosthesis researchers to develop a system, which could provide artificial vision to a large population of individuals with blindness. It has been demonstrated by earlier researches that stimulating the visual cortex area electrically can evoke spatial visual percepts, i.e. phosphenes. The goal of visual cortex prosthesis is to stimulate the visual cortex area and generate...
In this paper, a novel, wearable cardiac monitor (hereafter called WHAM) is proposed which allows a continuous and real-time monitoring of user's cardiac conditions. The proposed device is composed of 3 main components: a disposable electrode, a controller, and personal gateway (e.g., cellular phone, PDA, and smart phone etc.). The ECG signal is recorded according to the surface Laplacian of the body...
A wearable system able to monitor cardiopulmonary vital signs is presented. The innovative technological core of the system is based on the use of a textile conformable sensing cloth, where conducting and piezoresistive materials are integrated in form of fibres and yarns, giving rise to fabric sensors, electrodes and connections. Electrocardiogram and impedance pneumography signals are acquired through...
Following the early work of Brindley in the late 1960's, the NIH began intramural and extramural funding for stimulation of the primary visual cortex using fine-wire electrodes that are inserted into area V1 for the purpose of restoring vision in individuals with blindness. More recently researchers with experience in this project became part of our multi-institutional team with the intention to identify...
Electrical impedance tomography (hereinafter referred to as EIT) is 2-D or 3-D image of electrical impedance distribution in a living tissue. Unlike usual imaging methods, i.e., Xray-CT, MRI and US Imagings, EIT is used for imaging the information of tissue structure and functions. This paper provides a new estimation method as a fundamental study to realize a EIT for local biological tissue. Up until...
A boundary element (BE) model was developed of the electric potential field in the heart arising from electric potentials applied on implanted defibrillator electrodes. The model solved Laplace's equation for potential and was implemented using the BE method with realistic torso structures. An efficient out-of-core solver was developed, allowing any size problem to be solved, subject only to computer...
This paper proposes the use of differential electromyography (EMG) signals between muscles for phoneme classification, with which a Japanese speech synthesiser system can be constructed using fewer electrodes. In distinction from traditional methods using differential EMG signals between bipolar electrodes on the same muscle, an EMG signal is derived as differential between monopolar signals on two...
A simplified mathematical model has been developed in order to better understand local current spread when multiple simultaneous current sources are used in an epiretinal neuroprosthesis. To test the model, pairs of platinum electrodes of 430 mum diameter and an intra-pair spacing of 1 mm between centers, were arranged either in-line or in parallel, in a bath of physiological saline. Each pair was...
This paper details a strategy of discriminating finger motions using surface electromyography (EMG) signals, which could be applied to teleoperating a dexterous robot hand or controlling the advanced multi-fingered myoelectric prosthesis for hand amputees. Finger motions discrimination is the key problem in this study. Thus the emphasis is put on myoelectric signal processing approaches in this paper...
Hypnotic drugs induced sleep is usually different from physiological sleep in restoring body energy. The cause of the differences is not clear. To investigate the differences between these two types of sleep, in this study, hypnotic drug diazepam (DZP) induced sleep was compared with the recovery sleep following sleep deprivation. Power spectral analysis was used to reveal the different EEG features...
We propose new contractility indexes, in the work, which are equivalent to the conventional contractility (Ees) determined with the slope of left ventricular (LV) end-systolic pressure-volume relation. Nineteen patients with acute myocardial infarction (AMI) were recruited in the study. They received thrombolytic therapy within 24 hours after the AMI event, and their LV pressures and volumes were...
The purpose of the study is to investigate the effect of thrombolysis on the relationship between the left ventricular (LV) maximum elastance (Emax) and effective arterial elastance (Eart) in 20 patients with acute myocardial infarction (AMI). LV pressures and volumes of the patients were measured with Millar and multi-electrode volume conductance catheters during catheterization examination, respectively,...
A hybrid BSS-SVM method for distinguishing between left and right finger movements from the electroencephalogram (EEG) has been developed. Support vector machines (SVM) is used to effectively classify the extracted features incorporating blind source separation (BSS) and directed transfer functions (DTF). This is the basis for a brain computer interface (BCI). We analyzed 200 trials of 64 electrode...
A novel active surface Laplacian electroencephalogram (LEEG) sensor for the real-time mu rhythms detection has been developed in our study. Analog LEEG signals with high signal to noise ratio obtained directly by using the active sensor can reduce the duration and quantum error of digital signal processing and computation for the quick and precise control of brain-computer interface (BCI) systems...
Magnetic resonance electrical impedance tomography (MREIT) has been developed as a new medical imaging modality providing high-resolution conductivity and current density images. This paper is about MREIT of the breast. To show the feasibility of breast MREIT, we carried numerical simulations and breast phantom experiments. We found that an anomaly with 4 mm diameter can be visualized in a reconstructed...
In the present study an attempt was made to focus in the differences between obsessive-compulsive disorder (OCD) patients and healthy controls, as reflected by the P600 component of event-related potential (ERP) signals, to locate brain areas that may be related to working memory (WM) deficits. Neuropsychological research has yielded contradicting results regarding WM in OCD. Eighteen patients with...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.