scholarly journals Site dependence of ultrasonically induced electrical potentials in bone

2021 ◽  
Vol 1 (1) ◽  
pp. 012002
Author(s):  
Tsukasa Nakamura ◽  
Mineaki Takata ◽  
Itsuki Michimoto ◽  
Daisuke Koyama ◽  
Mami Matsukawa
Keyword(s):  
Electrical Potentials ◽  
Site Dependence

Bio-Inspired Submicron Electrodes

2003 ◽  
Vol 775 ◽  
Author(s):  
Ivan Stanish ◽  
Daniel A. Lowy ◽  
Alok Singh
Keyword(s):  
Electrode Surface ◽  
Structural Integrity ◽  
Electron Flow ◽  
Charge Storage ◽  
Electroactive Material ◽  
Electron Coupling ◽  
Strong Potential ◽  
Electrical Potentials ◽  
Submicron Scale ◽  
Potential Gradients

AbstractImmobilized polymerized electroactive vesicles (IPEVs) are submicron biocapsules capable of storing charge in confined environments and chemisorbing on surfaces. Methods to immobilize stable submicron sized electroactive vesicles and the means to measure electroactivity of IPEVs at nanolevels have been demonstrated. IPEVs can withstand steep potential gradients applied across their membrane, maintain their structural integrity against surfaces poised at high/low electrical potentials, retain electroactive material over several days, and reversibly mediate (within the membrane) electron flow between the electrode surface and vesicle interior. IPEVs have strong potential to be used for charge storage and electron coupling applications that operate on the submicron scale and smaller.

scholarly journals The strain-generated electrical potential in cartilaginous tissues: a role for piezoelectricity

2021 ◽  
Vol 13 (1) ◽  
pp. 91-100
Author(s):  
Philip Poillot ◽  
Christine L. Le Maitre ◽  
Jacques M. Huyghe
Keyword(s):  
Physiological Response ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Electrical Potential ◽  
Evidence Base ◽  
Piezoelectric Response ◽  
Mechanical Forces ◽  
Streaming Potentials ◽  
Cartilaginous Tissues ◽  
Electrical Potentials

AbstractThe strain-generated potential (SGP) is a well-established mechanism in cartilaginous tissues whereby mechanical forces generate electrical potentials. In articular cartilage (AC) and the intervertebral disc (IVD), studies on the SGP have focused on fluid- and ionic-driven effects, namely Donnan, diffusion and streaming potentials. However, recent evidence has indicated a direct coupling between strain and electrical potential. Piezoelectricity is one such mechanism whereby deformation of most biological structures, like collagen, can directly generate an electrical potential. In this review, the SGP in AC and the IVD will be revisited in light of piezoelectricity and mechanotransduction. While the evidence base for physiologically significant piezoelectric responses in tissue is lacking, difficulties in quantifying the physiological response and imperfect measurement techniques may have underestimated the property. Hindering our understanding of the SGP further, numerical models to-date have negated ferroelectric effects in the SGP and have utilised classic Donnan theory that, as evidence argues, may be oversimplified. Moreover, changes in the SGP with degeneration due to an altered extracellular matrix (ECM) indicate that the significance of ionic-driven mechanisms may diminish relative to the piezoelectric response. The SGP, and these mechanisms behind it, are finally discussed in relation to the cell response.

On ring solutions of neural field equations

2021 ◽  
pp. 363-371
Author(s):  
Rachid Atmania ◽  
Evgenii O. Burlakov ◽  
Ivan N. Malkov
Keyword(s):  
Activation Function ◽  
Stationary Solutions ◽  
Neural Field ◽  
Neuronal Activation ◽  
Field Equations ◽  
Broad Ring ◽  
Activation Threshold ◽  
Electrical Potentials ◽  
Radially Symmetric Solutions ◽  
Neural Field Equations

The article is devoted to investigation of integro-differential equation with the Hammerstein integral operator of the following form: ∂_t u(t,x)=-τu(t,x,x_f )+∫_(R^2)▒〖ω(x-y)f(u(t,y) )dy, t≥0, x∈R^2 〗. The equation describes the dynamics of electrical potentials u(t,x) in a planar neural medium and has the name of neural field equation.We study ring solutions that are represented by stationary radially symmetric solutions corresponding to the active state of the neural medium in between two concentric circles and the rest state elsewhere in the neural field. We suggest conditions of existence of ring solutions as well as a method of their numerical approximation. The approach used relies on the replacement of the probabilistic neuronal activation function f that has sigmoidal shape by a Heaviside-type function. The theory is accompanied by an example illustrating the procedure of investigation of ring solutions of a neural field equation containing a typically used in the neuroscience community neuronal connectivity function that allows taking into account both excitatory and inhibitory interneuronal interactions. Similar to the case of bump solutions (i. e. stationary solutions of neural field equations, which correspond to the activated area in the neural field represented by the interior of some circle) at a high values of the neuronal activation threshold there coexist a broad ring and a narrow ring solutions that merge together at the critical value of the activation threshold, above which there are no ring solutions.

Rapid Contractions and Associated Potentials in a Sand-Dwelling Anemone

1969 ◽  
Vol 51 (2) ◽  
pp. 513-528
Author(s):  
PETER E. PICKENS
Keyword(s):  
Maximum Size ◽  
Mechanical Stimulus ◽  
Retractor Muscle ◽  
Mechanical Stimuli ◽  
Nerve Impulses ◽  
Electrical Potentials ◽  
Spread Of Excitation ◽  
Electrical Stimuli ◽  
Withdrawal Response ◽  
Muscle Potential

1. Two kinds of electrical potentials can be recorded from the surface of the. retractor muscle of the anemone, Calamactis, during rapid contraction. These are large muscle action potentials and smaller pulses which are thought to be nerve spikes The latter resemble nerve impulses of higher organisms in that they are all-or-none and of short duration. 2. A nerve spike follows each of a pair of electrical stimuli, but the muscle potential and contraction occur only after the second shock, indicating that facilitation is required at the neuromuscular junction. 3. The size of the muscle potential and of the contraction are correlated with the interval between paired electrical stimuli. Maximum size is reached when stimuli are zoo msec. apart even though the minimum effective interval is 30 msec. 4. A muscle potential precedes contraction only along the upper part of the retractor muscle and this is the part that contracts rapidly during the withdrawal response. The lower retractor does not contract. 5. Conduction velocity along the upper retractor is higher than along the lower. The histological correlate of rapid conduction is a nerve net with large, long, longitudinally oriented fibres. 6. The refractory period of the conducting system of the upper retractor is shorter than that of the lower retractor. Consequently, spread of excitation toward the aboral end is limited if paired stimuli are further apart than 250-300 msec. 7. A mechanical stimulus which is just strong enough to elicit a withdrawal response evokes a single muscle potential of maximum size, suggesting that two nerve impulses closer together than 200 msec. precede the muscle potential. Stronger mechanical stimuli evoke a burst of muscle potentials.

Detection of EEG-Based Eye-Blinks Using A Thresholding Algorithm

2021 ◽  
Vol 6 (4) ◽  
pp. 6-12
Author(s):  
Dang-Khoa Tran ◽  
Thanh-Hai Nguyen ◽  
Thanh-Nghia Nguyen
Keyword(s):  
Detection Algorithm ◽  
Time Frequency ◽  
Eye Blink ◽  
Eye Blinks ◽  
User Training ◽  
Electrical Potentials ◽  
Ocular Artifact ◽  
Blink Detection ◽  
Thresholding Algorithm ◽  
Frequency Properties

In the electroencephalography (EEG) study, eye blinks are a commonly known type of ocular artifact that appears most frequently in any EEG measurement. The artifact can be seen as spiking electrical potentials in which their time-frequency properties are varied across individuals. Their presence can negatively impact various medical or scientific research or be helpful when applying to brain-computer interface applications. Hence, detecting eye-blink signals is beneficial for determining the correlation between the human brain and eye movement in this paper. The paper presents a simple, fast, and automated eye-blink detection algorithm that did not require user training before algorithm execution. EEG signals were smoothed and filtered before eye-blink detection. We conducted experiments with ten volunteers and collected three different eye-blink datasets over three trials using Emotiv EPOC+ headset. The proposed method performed consistently and successfully detected spiking activities of eye blinks with a mean accuracy of over 96%.

Transducer for recording electrical and mechanical chronic intestinal activity

1976 ◽  
Vol 41 (6) ◽  
pp. 942-945 ◽  
Author(s):  
A. Lambert ◽  
R. Eloy ◽  
J. F. Grenier
Keyword(s):  
Electrical Activity ◽  
Wheatstone Bridge ◽  
Displacement Transducer ◽  
Intestinal Wall ◽  
Mechanical Activity ◽  
Strain Gauges ◽  
Mechanical Displacement ◽  
Electrical Potentials ◽  
Intestinal Activity ◽  
Long Duration

An extraluminal displacement transducer has been developed for simultaneously recording the mechanical activity in two perpendicular directions andthe electrical activity of the intestinal serosa. The length variations in two perpendicular directions were measured by means of strain gauges bounded on two pairs of lamellae embedded in a rigid stand. The electrical activity was recorded by means of four electrodes situated at the extremity of these lamellae. The electrical gauges of each pair of lamellae are connected to form a Wheatstone bridge. This device allows establishment of a correlation between the mechanical displacement of the intestinal wall serosa and electrical potentials by means of studies of long duration.

scholarly journals Focal Stimulation of the Thalamic Reticular Nucleus Induces Focal Gamma Waves in Cortex

1998 ◽  
Vol 79 (1) ◽  
pp. 474-477 ◽  
Author(s):  
Kurt D. Macdonald ◽  
Eva Fifkova ◽  
Michael S. Jones ◽  
Daniel S. Barth
Keyword(s):  
Electrical Stimulation ◽  
Internal Capsule ◽  
Thalamic Reticular Nucleus ◽  
Gamma Activity ◽  
Reticular Nucleus ◽  
Cortical Arousal ◽  
Electrical Potentials ◽  
Gamma Frequency ◽  
Slow Potentials ◽  
Stimulation Of

MacDonald, Kurt D., Eva Fifkova, Michael S. Jones, and Daniel S. Barth. Focal stimulation of the thalamic reticular nucleus induces focal gamma waves in cortex. J. Neurophysiol. 79: 474–477, 1998. Electrical stimulation of the thalamic reticular nucleus (TRN; 0.5-s trains of 500-Hz 0.5-ms pulses at 5–10 μA) evokes focal oscillations of cortical electrical potentials in the gamma frequency band (∼35–55 Hz). These evoked oscillations are specific to either the somatosensory or auditory cortex and to subregions of the cortical receptotopic map, depending on what part of the TRN is stimulated. Focal stimulation of the internal capsule, however, evokes focal slow potentials, without gamma activity. Our results suggest that the TRN's role extends beyond that of general cortical arousal to include specific modality and submodality activation of the forebrain.

Understanding the electrical behavior of the action potential in terms of elementary electrical sources

2015 ◽  
Vol 39 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Javier Rodriguez-Falces
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Present Report ◽  
Electrical Potential ◽  
Ionic Currents ◽  
New Approach ◽  
Electrical Potentials ◽  
Proposed Model ◽  
Ionic Mechanisms ◽  
Human Electrophysiology

A concept of major importance in human electrophysiology studies is the process by which activation of an excitable cell results in a rapid rise and fall of the electrical membrane potential, the so-called action potential. Hodgkin and Huxley proposed a model to explain the ionic mechanisms underlying the formation of action potentials. However, this model is unsuitably complex for teaching purposes. In addition, the Hodgkin and Huxley approach describes the shape of the action potential only in terms of ionic currents, i.e., it is unable to explain the electrical significance of the action potential or describe the electrical field arising from this source using basic concepts of electromagnetic theory. The goal of the present report was to propose a new model to describe the electrical behaviour of the action potential in terms of elementary electrical sources (in particular, dipoles). The efficacy of this model was tested through a closed-book written exam. The proposed model increased the ability of students to appreciate the distributed character of the action potential and also to recognize that this source spreads out along the fiber as function of space. In addition, the new approach allowed students to realize that the amplitude and sign of the extracellular electrical potential arising from the action potential are determined by the spatial derivative of this intracellular source. The proposed model, which incorporates intuitive graphical representations, has improved students' understanding of the electrical potentials generated by bioelectrical sources and has heightened their interest in bioelectricity.

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