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The X-Delta model for through-skin volume conduction systems is introduced and analyzed. This new model has advantages over our previous X model in that it explicitly represents current pathways in the skin. A vector network analyzer is used to take measurements on pig skin to obtain data for use in finding the model's impedance parameters. An optimization method for obtaining this more complex model's...
We studied the mechanisms of spontaneous termination of atrial fibrillation in a biophysical model of human atria, during the eight seconds preceding termination. The earliest detectable changes in the cycle length and the number of wavefronts occurred about three seconds prior to termination. We compared the mechanisms involved in the right and left atrium and investigated the effects of atrial geometry...
Vibration has been increasingly sought after as new technique, due to its potential to increase muscle strength and positively affect bone remodeling. Currently, there are many vibration devices on the market advertised for different applications, in particular in sports and rehabilitation. All the available devices have two major drawbacks; firstly, they are not sufficiently adaptive to the individual...
Motor evoked potential (MEP) signals serve as an objective measure of the functional integrity of motor pathways in the spinal cord. Hence, they provide a reliable assessment of the extent of spinal cord injury (SCI). There are two methods currently being used for serial MEP recordings in rats: a low-frequency and a high-frequency method. In this paper, we compared the two methods and determined the...
In this paper, we propose a new method for diagnosing Alzheimer's disease (AD) on the basis of electroencephalograms (EEG). The method, which is termed ldquoPower Variance Function (PVF) methodrdquo, indicates the variance of the power at each frequency. By using the proposed method, the power of EEG at each frequency was calculated using Wavelet transform, and the corresponding variances were defined...
Photoacoustic imaging - also called optoacoustic imaging - is a new hybrid modality of high tissue contrast which is based on the varying optical properties of tissue. The acoustic signal generated by pulsed laser absorption reports tissue-specific information with high spatial resolution. To increase the intrinsic contrast in tissue, absorbing particles are of great interest for optical imaging because...
This paper presents a detailed study of the vibrations on the surface of the neck during a vocalization of predefined fundamental frequency and intensity. This study was carried out as part of a wider investigation into the use of laryngeal vibrations as a channel of communication. Another potential application of this study is in identifying a suitable location for a hands-free electro-larynx for...
Implantable neurostimulators for the treatment of epilepsy that are capable of sensing seizures can enable novel therapeutic applications. However, detecting seizures is challenging due to significant intracranial EEG signal variability across patients. In this paper, we illustrate how a machine-learning based, patient-specific seizure detector provides better performance and lower power consumption...
The use of therapeutic ultrasound delivered via small diameter wire waveguides may represent an emerging minimally invasive approach in the treatment of chronic total occlusions (CTOs), calcified and fibrous plaques. The distal-tip mechanical vibrations (typically 0-210 mum peak-to-peak) have been reported to debulk rigid calcified and fibrous tissues while healthy elastic arterial tissue remains...
An apnea detection method based on spectral analysis was used to assess the performance of three ECG derived respiratory (EDR) signals. They were obtained on R wave area (EDR1), heart rate variability (EDR2) and R peak amplitude (EDR3) of ECG record in 8 patients with sleep apnea syndrome. The mean, central, peak and first quartile frequencies were computed from the spectrum every 1 min for each EDR...
A new approach to study the pulse transmission between the cerebrovascular bed and the intracranial space is presented. In the proposed approach, the normalized power transmission between ABP and ICP has got the main attention rather than the actual power transmission. Evaluating the gain of the proposed transfer function at any single frequency can reveal how the percentage of contribution of that...
A number of experimental investigations have evidenced the extraordinary sensitivity of neuronal cells to weak input stimulations, including electromagnetic (EM) fields. Moreover, it has been shown that biological noise, due to random channels gating, acts as a tuning factor in neuronal processing, according to the stochastic resonant (SR) paradigm. In this work the attention is focused on noise arising...
Recordings were performed on the rat paramedian lobule of the cerebellum with a surface micro-electrode array during hand licking and quiet states. The Fast Fourier Transform (FFT) and average coherence both showed a change in the frequency distributions between active and quiet conditions. The signals were segregated into different frequency bands and the signal compositions were analyzed. In each...
This paper reports a comparative study of feature extraction methods regarding cardiac arrhythmia classification, using state of the art Hidden Markov Models. The types of beat being selected are normal (N), premature ventricular contraction (V) which is often precursor of ventricular arrhythmia, two of the most common class of supra-ventricular arrhythmia (S), named atrial fibrillation (AF), atrial...
Electrogastrographic signal (EGG) is considered to be one of the less interesting from both registration and interpretation point of view. There are several reasons of that two facts. EGG presents gastric myoelectrical activity measured by several electrodes attached on the abdomen. Unfortunately the registration procedure does not deliver a pure signal as EGG is usually associated with some interferences...
The delivery of high frequency alternating currents (HFAC) to peripheral nerves has been shown to produce a rapid and reversible nerve conduction block at the site of the electrode, and holds therapeutic promise for diseases associated with undesired or pathological neural activity. It has been known since 1939 that the configuration of an electrode used for nerve block can impact the quality of the...
High frequency alternating current (HFAC) waveforms reversibly block conduction in mammalian peripheral nerves. The initiation of the HFAC produces an onset response in the nerve before complete block occurs. An amplitude ramp, starting from zero amplitude, is ineffective in eliminating this onset response. In fact, it makes the onset worse. We postulated that initiating the ramp from a non-zero amplitude...
In this study human motor cortical activity was recorded with a customized micro-ECoG grid during individual finger movements. The quality of the recorded neural signals was characterized in the frequency domain from three different perspectives: (1) coherence between neural signals recorded from different electrodes, (2) modulation of neural signals by finger movement, and (3) accuracy of finger...
Complementary to axial, lateral and elevational displacement and strain can provide important information on the mechanical properties of biological soft tissues. In this paper, the effects of key parameters on the lateral displacement estimation were investigated in simulations and validated in phantom experiments. The performance of the lateral estimator was evaluated by measuring its associated...
Nerve conduction in peripheral mammalian nerves can be blocked by high frequency alternating current (HFAC) waveforms. However, one of the disadvantages of HFAC block is that it produces an intense burst of firing in the nerve when the HFAC is first turned on. This is a significant obstacle to the clinical implementation of HFAC block. In this paper we present a method to produce HFAC block without...
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