The implementation of systems to restore sensorimotor functions in person with neurological disabilities is an important research area. In the past, many studies have been carried out to develop closed-loop neuroprostheses based on the processing of electroneurographic (ENG) signals recorded from physiological sensors using cuff electrodes. However, the potential of ...

BACKGROUND: Measurements of auto and cross covariance functions are frequently used to investigate neural systems. In interpreting this data, it is commonly assumed that the largest contribution to the recordings comes from sources near the electrode. However, the potential recorded at an electrode represents the superimposition of the potentials generated ...

A laser Doppler system for intracerebral measurements during stereotactic and functional neurosurgery is presented. The system comprises a laser Doppler perfusion monitor, an optical probe adapted for the Leksell Stereotactic System and a personal computer with software for acquisition, data analysis and presentation. The software makes it possible to present ...

The purpose of this study is to evaluate the performance to measure ECG recording based on signal-to-noise ratio of ECG signals recorded with three types of electrodes in four experimental conditions for discussion on appropriate form of the electrodes. The wrist band shaped capacitively-coupled electrodes have been developed. We evaluated ...

Electrical impedance tomography (EIT) produces an image of the electrical impedance distribution of tissues in the body, using electrodes that are placed on the periphery of the imaged area. These electrodes inject currents and measure voltages and from these data, the impedance can be computed. Traditional EIT systems usually inject ...

The electrocardiogram (ECG) was measured by non-contact, non-restraint and unconscious method using capacitively-coupled electrodes made of electro-conductive cloth while subjects lay on bed wearing their clothes. These electrodes are very sensitive so measure not only signals but noise. The seat grounded, which arranged under the electrode could suppress noise. Two ...

A neural prosthesis (NP) has two applications: permanent assistance of function, and temporary assistance that contributes to long-term recovery of function. Here, we address control issues for a therapeutic NP which uses surface electrodes. We suggest that the effective NP for therapy needs to implement rule-based control. Rule-based control relies ...

Electrodes are the essential elements of clinical neurophysiology both in recording of neural activity and in functional electrical stimulation of the nervous system. Therefore it is important to understand the potential complications of using electrodes. In this paper, the factors that influence the chance of electrode related injury are discussed ...

PURPOSE: To develop an improved, easy, and safe method for reliably eliciting electrical phosphenes and to compare reported perceptions and values of chronaxie and rheobase in healthy individuals and patients with distinct ophthalmic diseases. METHODS: DTL electrodes were used with a four-alternative, forced-choice method to determine psychophysically the strength-duration curves ...

Auditory stream segregation was measured in cochlear implant (CI) listeners using a subjective "Yes-No" task in which listeners indicated whether a sequence of stimuli was perceived as two separate streams or not. Stimuli were brief, 50-ms pulse trains A and B, presented in an A_B_A_A_B_A... sequence, with 50 ms in ...

The effect of a stationary electric field on a water droplet with a diameter of several tens micrometers in oil was examined. Such a droplet exhibits repetitive translational motion between the electrodes in a spontaneous manner. The state diagram of this oscillatory motion was deduced; at 0-20 V the droplet ...

Categorical loudness scaling of electric and acoustic stimuli was performed in cochlear implant (CI) recipients equipped with Nucleus systems in order to achieve a normal loudness perception in the whole dynamic range of acoustic input. For each electrode, the lower and upper limits of electric stimulus were defined by the ...

OBJECTIVE: AutoNRT is an automated system that measures electrically evoked compound action potential (ECAP) thresholds from the auditory nerve with the Nucleus Freedom cochlear implant. ECAP thresholds along the electrode array are useful in objectively fitting cochlear implant systems for individual use. This paper provides the first detailed description of ...

The ability of cochlear implantees to detect an increment in current level at one of many stimulated electrodes was investigated. Such changes in the electric profile provide information for cochlear implantees to discriminate numerous sounds, especially vowels. In Experiment 1, sensitivity to increases in current level at one stimulation site ...

Five users of cochlear implants who had residual acoustic hearing in the implanted ear postoperatively participated in a study comparing the percepts elicited by acoustic and electric stimuli. The stimuli comprised pulse trains delivered to single electrodes and pure tones presented ipsilaterally. In the experiments, 12 equally loud stimuli with ...

A reversible electrical block of the pudendal nerves may provide a valuable method for restoration of urinary voiding in individuals with bladder-sphincter dyssynergia. This study quantified the stimulus parameters and effectiveness of high frequency (HFAC) sinusoidal waveforms on the pudendal nerves to produce block of the external urethral sphincter (EUS). ...

The primary goal of this study was to examine electrophysiologic measures of channel interaction, electrode pitch discrimination ability using a pitch-ranking task, and behavioral threshold levels in individuals implanted with a straight electrode array versus a perimodiolar array. It was hypothesized that perimodiolar arrays should yield lower thresholds, less channel ...

Current neuroprosthetic systems based on electro-physiological recording have an extended, yet finite working lifetime. Some posited lifetime-extension solutions involve improving device biocompatibility or suppressing host immune responses. Our objective was to test an alternative solution comprised of applying a voltage pulse to a microelectrode site, herein termed "rejuvenation." Previously, investigators ...

Most wired active electrodes reported so far have a gain of one and require at least three wires. This leads to stiff cables, large connectors and additional noise for the amplifier. The theoretical advantages of amplifying the signal on the electrodes right from the source has often been described, however, ...

The aim of this study was to assess the frequency-position function resulting from electric stimulation of electrodes in cochlear implant subjects with significant residual hearing in their nonimplanted ear. Six cochlear implant users compared the pitch of the auditory sensation produced by stimulation of an intracochlear electrode to the pitch ...

The objective of this study was to compare the psychophysical performance of patients using the Nucleus Contour electrode array with that of patients using the straight banded-electrode array. In particular, we wished to consider how psychophysical parameters would differ for an electrode array positioned closer to the modiolus, and how ...

Greenwood's frequency-position function for the organ of Corti (OC) is commonly used to estimate represented frequencies for cochlear implant (CI) electrodes, both in temporal bone studies and in imaging studies of living CI recipients. However, many contemporary CIs position stimulating electrodes near the modiolus, directly targeting the spiral ganglion (SG) ...

Steady-state visual evoked potentials (SSVEPs) are used in cognitive and clinical studies of brain function because of excellent signal-to-noise ratios and relative immunity to artifacts. SSVEPs also provide a means to characterize preferred frequencies of neocortical dynamic processes. In this study, SSVEPs were recorded with 110 electrodes while subjects viewed ...

Typically intracortical electrodes are required to puncture the intact pia mater during insertion which in the process can lead to brain dimpling and trauma. Furthermore, there is interest in the development of more flexible substrates to reduce relative micromotion after implantation, but such device have difficulty penetrating the pia without ...

Electrocardiographic (ECG) signals are affected by several kinds of artifacts, that may hide vital signs of interest. Motion artifacts, due to the motion of the electrodes in relation to patient skin, are particularly frequent in bioelectrical signals acquired by wearable systems. In this paper we propose different approaches in order ...

Electroencephalography (EEG) signals are spatio-temporal. EEG has very good temporal resolution but typically doesn't possess high spatial resolution. The surface Laplacian enhances the spatial resolution and selectivity of the surface electrical activity. Concentric ring electrodes have been shown to estimate the surface Laplacian directly with significantly better spatial resolution than ...

Pattern recognition based myoelectric controllers rely on a fundamental assumption that the patterns detected under a given electrode are repeatable for a given state of muscle activation. Consequently, electrode displacements on the skins surface affect the classification accuracy of the pattern based myoelectric controller. The effects of electrode displacement can ...

The ideal cochlear implant electrode array positioning enables stimulation over a range of cochlear positions whose characteristic frequencies cover the frequency range of speech and match the speech processor filter frequencies. However, the electrode positions achieved in practice may not meet this specification. Users of conventional monaural cochlear implants seem ...

We report a neural microelectrode array design that leverages the recording properties of conventional microwire electrode arrays with the additional features of precise control of the electrode geometries. Using microfabrication techniques, a neural probe array is fabricated that possesses a flexible polyimide-based cable. The performance of the design was tested ...

The hybrid stimulation in cochlear implants requires changes in the design of electrode arrays. A new generation of flat electrode arrays that does not damage the cochlea is being developed. For the insertion of these flat array electrodes a groove must be milled in the antero-inferior area of the round ...

A new flexible sensor for in vitro experiments was developed to measure the surface potential, Phi, and its gradient, E (electric near field), at given sites of the heart. During depolarisation, E describes a vector loop from which direction and magnitude of local conduction velocity theta can be computed. Four ...

A potential shortcoming of existing multichannel cochlear implants is electrical-field summation during simultaneous electrode stimulation. Electrical-field interactions can disrupt the stimulus waveform prior to neural activation. To test whether speech intelligibility can be degraded by electrical-field interaction, speech recognition performance and interaction were examined for three Clarion electrode arrays: the ...

BACKGROUND: Earliest postshock activation following failed defibrillation shocks slightly lower than the defibrillation threshold (DFT) in large animals appears to arise from a focus. We tested the hypothesis that these foci are caused by early or delayed afterdepolarizations (EADs or DADs) by performing epicardial electrical mapping and giving the EAD ...

'Common Electrode' microneurography (i.e. stimulating a nerve and recording return afferent neural activity through the same microelectrode facilitates investigation of linkages between sensory and motor nervous systems in humans. Currently there is no commercial product designed specifically to conduct common electrode microneurography experiments. However, such experiments would advance investigations in ...

We experimentally study the transient clustering behavior of viable yeast cells in a dilute suspension suddenly subjected to a nonuniform alternating current (AC) electric field of a microelectrode device. The frequency of the applied electric field is varied to identify two distinct regimes of positive dielectrophoresis. In both regimes, the ...

We conducted an initial study on tactile sensory characteristics of the lips by applying electrotactile array stimulation on the center surfaces of the upper and lower lips. We performed experiments of threshold measurement and rating of two-line separation to evaluate the tactile sensitivity and spatial discriminating ability of the lips, ...

Empirical evidence is presented suggesting that the innervation zone of the brachial biceps shifts relative to recording electrodes with changes in joint angle. Myoelectric signal data were acquired from five subjects using a 16-channel linear electrode array, and analyzed to determine a reversal in signal propagation direction indicating innervation zone ...

Understanding the basic mechanisms of excitability through the cardiac cycle is critical to both the development of new implantable cardiac stimulators and improvement of the pacing protocol. Although numerous works have examined excitability in different phases of the cardiac cycle, no systematic experimental research has been conducted to elucidate the ...

Since the development of knockout animals, the mouse has become an important model to study gastrointestinal motility. However, little information is available on the electrical and contractile activities induced by distension in the murine small intestine. Spatiotemporal electrical mapping and mechanical recordings were made from isolated intestinal segments from different ...

Simultaneous or near-simultaneous activation of adjacent cochlear implant electrodes can produce pitch percepts intermediate to those produced by each electrode separately, thereby increasing the number of place-pitch steps available to cochlear implant listeners. To estimate how many distinct pitches could be generated with simultaneous dual-electrode stimulation, the present study measured ...

BACKGROUND: Studies of ventricular fibrillation (VF) in small mammals have revealed localized sustained stationary reentry. However, studies in large mammals with surface mapping techniques have demonstrated only relatively short-lived rotors. The purpose of this study was to identify whether sustained high-frequency activation with low beat-to-beat variability was present at intramural ...

Two thin-film microelectrode arrays with integrated circuitry have been developed for extracellular neural recording in behaving animals. An eight-site probe for simultaneous neural recording and stimulation has been designed that includes on-chip amplifiers that can be individually bypassed, allowing direct access to the iridium sites for electrical stimulation. The on-probe ...

The effect of rate of stimulation on spectral shape perception was measured in six users of the Nucleus CI24 cochlear implant. Three spectral shapes were created by using three profiles of current across seven electrode positions. Each current profile was replicated in three stimuli that interleaved stimulus pulses across the ...

OBJECTIVE: We compared behavioral judgment of maximum comfortable loudness levels (C levels) and behavioral thresholds (Ts) for straight and Contour electrode arrays with two objective thresholds, electrically elicited stapedial reflex thresholds (eSRTs) and electrically elicited compound action potential thresholds (eCAP thresholds), on experienced adult cochlear implant users. Next, we evaluated ...

The photoelectrochemical behavior of TiO2 thin film electrodes, photocatalytically modified with Se islands, is described. The TiO2 thin films were electrodeposited on transparent conducting oxide glass substrates. The resultant electrode forms a n-TiO2/p-Se "photochemical diode" which, in turn, contacts an electrolyte phase. Both transient photocurrent profiles (in response to excitation ...

STUDY DESIGN: To establish a methodology for the neurophysiologic study of mechanoreceptors in the cervical facet joint capsule. OBJECTIVES: To test a custom designed miniature dual bipolar electrode for recording the neural activity in cervical dorsal roots. To determine if the neural activity from different receptors in the capsule can ...

Three test subjects blind from retinitis pigmentosa were implanted with retinal prostheses as part of a FDA-approved clinical trial. The implant consisted of an extraocular unit that contained electronics for wireless data, power, and generation of stimulus current, and an intraocular unit that consisted of 16 platinum stimulating electrodes arranged ...

We designed a 24-field array and an on-line control box that selects which and how many of 24 fields will conduct electrical charge during functional electrical stimulation. The array was made using a conductive microfiber textile, silver two-component adhesive, and the conductive ink imprint on the polycarbonate. The control box ...

The authors present practical evidence for the usefulness of intraoperative monitoring with surface electromyograms (sEMGs) from the affected muscles to assist electrode implantation and lesioning in patients with movement disorders. In 22 consecutive patients with various movement disorders, sEMGs were monitored in selected muscles during stereotactic surgery that involved either ...

This study addresses methodological issues on surface electromyographic (EMG) signal recording from jaw elevator muscles. The aims were (i) to investigate the sensitivity to electrode displacements of amplitude and spectral surface EMG variables, (ii) to analyse if this sensitivity is affected by the inter-electrode distance of the bipolar recording, and ...