Propagation Of Electrical Signals Research Articles

Poincaré plot analysis of ECG uncovers beneficial effects of omaveloxolone in a mouse model of Friedreich's ataxia.

Friedreich's ataxia (FA) is a rare inherited neuromuscular disorder, where most patients die from lethal cardiomyopathy and arrhythmias. Mechanisms leading to arrhythmic events in FA patients are poorly understood. This study aims to examine cardiac electrical signal propagation in mouse model of FA with severe cardiomyopathy and evaluate effects of omaveloxolone (OMAV), the first FDA-approved therapy. Cardiac-specific MCK-Cre frataxin knockout (FXN-cKO) mice were used to mimic FA cardiomyopathy. In vivo surface ECG recordings, western blotting, qPCR, and histochemistry were performed. Characteristics like long QT syndrome, interatrial block, and ST-segment abnormalities in FA patients were identified in FXN-cKO mice. FXN-cKO mice exhibited sexual dimorphism in electrical signal propagation and cardiac structural integrity. Untreated FA males showed increased ventricular propagation intervals, while females exhibited delayed atrial propagation. OMAV showed no significant therapeutic effect on average ECG time intervals but improved chamber-specific waveforms when aggregated frequency distributions were analyzed. The J-wave was absent in FXN-cKO male mice but reappeared with OMAV treatment. Poincaré plots revealed disparate idiopathic arrhythmias with multi-clustering events in individual mice with high incidence in FXN-cKO males. OMAV treatment reduced multi-clustering events to a single cluster; however, ANS dysfunction still remained. Our study revealed significant electrical propagation disturbances and sexual dimorphism in FXN-cKO mice with severe cardiomyopathy. Poincaré plots identified irregularities in heart rhythm and ANS dysfunction. OMAV improved heart function by stabilizing early repolarization and reducing disparate arrhythmias. This work stresses sex-specific ECG interpretations and alternative mathematical approaches for drug testing in FA models.

Anisotropic conductive scaffolds for post-infarction cardiac repair.

Myocardial infarction (MI) remains one of the most common and lethal cardiovascular diseases (CVDs), leading to the deterioration of cardiac function due to myocardial cell necrosis and fibrous scar tissue formation. Myocardial infarction (MI) remains one of the most common and lethal cardiovascular diseases (CVDs), leading to the deterioration of cardiac function due to myocardial cell necrosis and fibrous scar tissue formation. After MI, the anisotropic structural properties of myocardial tissue are destroyed, and its mechanical and electrical microenvironment also undergoes a series of pathological changes, such as ventricular wall stiffness, abnormal contraction, conduction network disruption, and irregular electrical signal propagation, which may further induce myocardial remodeling and even lead to heart failure. Therefore, bionic reconstruction of the anisotropic structural-mechanical-electrical microenvironment of the infarct area is key to repairing damaged myocardium. This article first summarizes the pathological changes in muscle fibre structure and conductive microenvironment after cardiac injury, and focuses on the classification and preparation methods of anisotropic conductive materials. In addition, the effects of these anisotropic conductive materials on the behavior of cardiac resident cells after myocardial infarction, such as directional growth, maturation, proliferation and migration, and the differentiation fate of stem cells and the possible molecular mechanisms involved are summarized. The design strategies for anisotropic conductive scaffolds for myocardial repair in future clinical research are also discussed, with the aim of providing new insights for researchers in related fields.

Endoplasmic Reticulum Calcium Signaling in Hippocampal Neurons.

The endoplasmic reticulum (ER) is a key organelle in cellular homeostasis, regulating calcium levels and coordinating protein synthesis and folding. In neurons, the ER forms interconnected sheets and tubules that facilitate the propagation of calcium-based signals. Calcium plays a central role in the modulation and regulation of numerous functions in excitable cells. It is a versatile signaling molecule that influences neurotransmitter release, muscle contraction, gene expression, and cell survival. This review focuses on the intricate dynamics of calcium signaling in hippocampal neurons, with particular emphasis on the activation of voltage-gated and ionotropic glutamate receptors in the plasma membrane and ryanodine and inositol 1,4,5-trisphosphate receptors in the ER. These channels and receptors are involved in the generation and transmission of electrical signals and the modulation of calcium concentrations within the neuronal network. By analyzing calcium fluctuations in neurons and the associated calcium handling mechanisms at the ER, mitochondria, endo-lysosome and cytosol, we can gain a deeper understanding of the mechanistic pathways underlying neuronal interactions and information transfer.

Advancing 3D Engineered In Vitro Models for Heart Failure Research: Key Features and Considerations.

Heart failure is characterized by intricate myocardial remodeling that impairs the heart's pumping and/or relaxation capacity, ultimately reducing cardiac output. It represents a major public health burden, given its high prevalence and associated morbidity and mortality rates, which continue to challenge healthcare systems worldwide. Despite advancements in medical science, there are no treatments that address the disease at its core. The development of three-dimensional engineered in vitro models that closely mimic the (patho)physiology and drug responses of the myocardium has the potential to revolutionize our insights and uncover new therapeutic avenues. Key aspects of these models include the precise replication of the extracellular matrix structure, cell composition, micro-architecture, mechanical and electrical properties, and relevant physiological and pathological stimuli, such as fluid flow, mechanical load, electrical signal propagation, and biochemical cues. Additionally, to fully capture heart failure and its diversity in vivo, it is crucial to consider factors such as age, gender, interactions with other organ systems and external influences-thereby recapitulating unique patient and disease phenotypes. This review details these model features and their significance in heart failure research, with the aim of enhancing future platforms that will deepen our understanding of the disease and facilitate the development of novel, effective therapies.

Resolving spatiotemporal electrical signaling within the islet via CMOS microelectrode arrays.

Glucose-stimulated beta-cells exhibit synchronized calcium dynamics across the islet that recruit beta-cells to enhance insulin secretion. Compared to calcium dynamics, the formation and cell-to-cell propagation of electrical signals within the islet are poorly characterized. To determine factors that influence the propagation of electrical activity across the islet underlying calcium oscillations and beta-cell synchronization, we used high-resolution CMOS multielectrode arrays (MEA) to measure voltage changes associated with the membrane potential of individual cells within intact C57BL6 mouse islets. We measured fast (milliseconds, spikes) and slow (seconds, waves) voltage dynamics. Single spike activity and wave signal velocity were both glucose-dependent, but only spike activity was influenced by NMDA receptor activation or inhibition. A repeated glucose stimulus revealed a highly responsive subset of cells in terms of spike activity. When islets were pretreated for 72 hours with glucolipotoxic medium, the wave velocity was significantly reduced. Network analysis confirmed that in response to glucolipotoxicity the synchrony of islet cells was affected due to slower propagating electrical waves and not due to altered spike activity. In summary, this approach provided novel insight regarding the propagation of electrical activity and the disruption of cell-to-cell communication due to excessive stimulation.

Engineering the Functional Expansion of Microneedles.

Microneedles (MNs), composed of an array of micro-sized needles and a supporting base, have transcended their initial use to replace hypodermic needles in drug delivery and fluid collection, advancing toward multifunctional platforms. In this review, four major areas are summarized in interdisciplinary engineering approaches combined with MNs technology. First, electronics engineering, the most extensively researched field, enables applications in biomonitoring, electrical stimulation, and closed-loop theranostics through the generation, transmission, and transformation of electrical signals. Second, in electromagnetic engineering, the responsiveness of electromagnetic induction offers prospects for remote and programmable therapeutic applications. Third, photonic engineering endows MNs with novel functionalities, such as waveguiding and photonic manipulation to enhance optical therapeutic capabilities and facilitate the visualization of disease progression and treatment processes. Lastly, it reviewed the role of mechanical engineering in conferring shape adaptability and programmable motion features necessary for various MNs applications. This review focuses on the functionalities that emerge from the intersection of MNs with complementary engineering technologies, aiming to inspire further research and innovation in microneedle technology for biomedical applications.

A computationally efficient anisotropic electrophysiological multiscale uterus model: From cell to organ and myometrium to abdominal surface

Background and objectivePreterm labor is a global problem affecting the health of newborns. Despite numerous studies reporting electrophysiological changes throughout pregnancy, the underlying mechanism that triggers labor remains unclear. Electrophysiological modeling can provide additional information to better understand the physiological transition from pregnancy to labor. Previous uterine electrophysiological models do not consider either the tissue thickness or fiber structure, which have both been shown to significantly impact propagation patterns. MethodsThis paper presents a parallel computational model of the uterus using the bioengineering modeling environment OpenCMISS. This model is a multiscale anisotropic model that spans different levels from cell to organ. At the cellular level, the model utilizes a mathematical representation of uterine myocytes based on multiple ion channels. In the 3D uterine model, fiber structures are added, ranging from horizontal rings in the inner layer to vertically downward fibers in the outer layer, to more accurately depict the electrophysiological activities of the uterus. Additionally, we have developed a multilayer volume conduction model based on the boundary element method to describe the propagation of electrical signals from the myometrium to the abdominal surface. ResultsOur model can not only reproduce faithfully both local non-propagated and global propagated electrical activity, but also simulate the fast wave low and fast wave high components of the electrohysterogram (EHG) on the abdominal surface. The model results support the hypothesis that the fast wave high of the EHG signal is related to uterine excitability and fast wave low is related to signal propagation. The amplitude of the simulated signal on the abdominal surface falls in the ranges of real EHG data, which is inversely proportional to the abdominal subcutaneous fat thickness, and the signal waveform highly depends on electrode position and the relative distance to the pacemaker. In addition, the propagation velocity is highly dependent on the uterus geometry and falls in the real-world data range ConclusionsOur models facilitate a better understanding of the electrophysiological changes of the uterus during pregnancy and labor, and allow for an investigation of drug effects and/or structural or anatomical abnormalities.

Quantifying cardiac tissue heterogeneity using high-density grid catheter: validation in porcine model

Abstract Background and Objectives Characterizing cardiac substrate is crucial for diagnosing and treating cardiac arrhythmias due to its association with the presence of fibrotic tissue. Omnipolar Electrogram (EGM) technology provides orientation-independent signal generation and instantaneous propagation direction determination. Although traditionally, the amplitude of the bipolar signal has been the most used metric, it alone does not suffice for comprehensive tissue characterization. Recently, a novel metric has been developed to quantify the degree of directional propagation disorganization within cardiac tissue, defined as Vector Field Heterogenity (VFH)[1] that can provide additional insights to the tissue characterization. Due to the presence of tissues with varying impedance, changes in the direction of propagation of cardiac electrical signals can occur. Therefore, the objective of this study is to characterize how the presence of fibrotic or necrotic tissue can influence the disorganization of electrical activity propagation, and thus assess the effectiveness of the heterogeneity metric in characterizing these tissues. Method We worked with a database of a female swine records of the left atrium. These records include data pre and post-ablation by electroporation. From the unipolar signals available in the database, we have calculated the Omnipolar EGMs in cross configuration. From the omnipolar signals, we calculated the propagation direction. On this propagation direction, we applied the heterogeneity metric for each catheter position along all the left atrium. This metric has a normalized range between 0 and 1, 0 describing the minimum disorganization and 1 the maximum. These calculations have been applied in the same way in the registers pre and post-ablation to evaluate the differences. Results Pre-procedure bipolar peak-to-peak voltages averaged 2.7591mV (SD = 3.4257), decreasing post-procedure to 0.754mV (SD = 1.1666), (p< 0.0001) indicating a significant decrease in bipolar amplitude following ablation. Heterogeneity scores increased post-ablation (mean = 0.3753, SD = 0.21218; post: mean = 0.53526, SD = 0.1320, p<0.0001. This indicates that after ablation, not only does the signal amplitude decrease, but also the level of disorganization of electrical propagation increases. These findings are visually depicted in Figure 1. Conclusion The ablation procedure led to reduced tissue electrical activity, manifested by decreased amplitude and increased propagation heterogeneity, indicative of tissue disorganization. Transitioning from homogeneous to heterogeneous conduction post-ablation suggests the presence of necrotic tissue, hindering uniform wave propagation. This highlights the significance of heterogeneity scoring in evaluating tissue health and ablative intervention outcomes.Figure 1.Catheter HD Grid

A venom peptide-induced NaV channel modulation mechanism involving the interplay between fixed channel charges and ionic gradients

Venoms are used by arthropods either to immobilise prey or as defence against predators. Our study focuses on the venom peptide, Ta3a, from the African ant species, Tetramorium africanum and its effects on voltage-gated sodium (NaV) channels, which are ion channels responsible for the generation of electrical signals in electrically excitable cells, such as neurons. Using the NaV1.7 isoform as our model NaV channel we show that Ta3a prolongs single channel active periods with increased open probability and induces non-inactivating whole-cell currents. Ta3a-affected NaV1.7 channels exhibit a leftward (hyperpolarising) shift in activation threshold, constitutive activity even in the absence of an activating voltage stimulus, and at cell membrane voltages where channels are normally silent. Current-voltage experiments show that Ta3a shifts the voltage at which NaV current changes direction (reversal potential) by altering the local ionic concentration of permeant ions (Na+) rather than changing the channel’s preference for ionic species. We propose a model where Ta3a maintains the positively charged voltage-sensing (S4) domains of the channel in the activated configuration where their electric field is exposed to the extracellular membrane surface to create an ionic bilayer comprising S4 domains and mobile anions (Cl−). This bilayer has a depolarising effect on the cell membrane, thus reducing the amount of externally applied voltage required for channel activation.

Diverse soliton solutions to the nonlinear partial differential equations related to electrical transmission line

This paper introduces novel traveling wave solutions for the (1+1)-dimensional nonlinear telegraph equation (NLTE) and the (2+1)-dimensional nonlinear electrical transmission line equation (NETLE). These equations are pivotal in the transmission and propagation of electrical signals, with applications in telegraph lines, digital image processing, telecommunications, and network engineering. We applied the improved tanh technique combined with the Riccati equation to derive new solutions, showcasing various solitary wave patterns through 3D surface and 2D contour plots. These results provide more comprehensive solutions than previous studies and offer practical applications in communication systems utilizing solitons for data transmission. The proposed method demonstrates an efficient calculation process, aiding researchers in analyzing nonlinear partial differential equations in applied mathematics, physics, and engineering

Abstract Mo054: Long Noncoding RNA LINC00667 Downregulation Leads to SCN5A Alternative Splicing and Arrhythmogenesis

Background: The voltage-gated sodium channel SCN5A, which encodes the Nav1.5 protein, is integral to the propagation of electrical signals in cardiac tissue. SCN5A expression is diminished in cardiomyopathy, significantly increasing the susceptibility to arrhythmias. This reduction in channel activity can be attributed to decreased mRNA stability coupled with aberrant mRNA splicing. The underlying mechanisms driving the dysregulation of mRNA splicing under pathophysiological conditions remain poorly understood. Objective: This study explores the role of long noncoding RNA LINC00667 in the abnormal alternative splicing of SCN5A mRNA. Methods: LINC00667 expression was analyzed using public databases, human heart tissue, iPSC-derived cardiomyocytes (iPSCMs), and cell lines. The impact of SCN5A on action potentials and sodium currents was studied in iPSCMs. LINC00667 and SCN5A expressions were measured using qRT-PCR, while Nav1.5 protein levels were assessed through Western blot. Alternative splicing of SCN5A mRNA was examined using PCR with exon-specific primers. Gene ontology and in silico analysis identified RNA binding proteins (RBPs) potentially interacting with LINC00667. RNA immunoprecipitation (RIP) assays confirmed direct binding with key splice factors. Group differences were assessed using 2-tailed Student’s t-tests, with P < 0.05 indicating significance. Results: LINC00667, found at chromosome 18p11.31, is expressed in the human heart and associated cells, including cardiomyocytes. Its levels are inversely related to arrhythmic risk, decreasing in heart failure and ischemic cardiomyopathy as well as under hypoxic conditions. Gene ontology linked RBPs to SCN5A mRNA splicing, with RBM25, RBM5, and TIA1 identified as LINC00667 interactors. LINC00667 reduction affected regions of SCN5A mRNA encompassing Exons 6, 24, and 28, which could potentially be linked to decreased function/expression or increased unfolded protein response (UPR). Abnormal RNA splicing decreased SCN5A-encoded sodium current, reduced action potential upstroke velocity, and shortened AP duration without altering resting membrane potential. Conclusion: Decreased LINC00667 releases splicing factors that result in abnormal SCN5A mRNA splicing and reduced sodium current. Since LINC00667 is reduced in cardiomyopathy, overexpression may be antiarrhythmic by preventing sodium channel downregulation.

A cleaner and eco-friendly approach to simultaneous extraction and characterization of essential oil and pectin from Assam lemon peel and its application for energy generation through TENG devices

Scientists have been working on developing a green bio-TENG for portable remote devices, including wearables in the biomedical sector. The process involves obtaining pectin, a green material with anti-microbial properties, as a Triboelectric material. This study focuses on the extraction of essential oil (EO) and pectin from Assam lemon peel simultaneously. A single-step strategy was optimized using a central composite design-based response surface approach. The extracted pectin yielded 4.19 ± 0.31 % and 11.53 ± 0.11 %, respectively. GC-MS analysis revealed 52 volatile components in the Assam lemon EOs, with limonin being 94.47 % and β-Bisabolene being 1.26 %. Only khusilal was found in the EOs, a rare discovery in the scientific domain. The extracted pectin showed good purity and antimicrobial properties. The in vitro activities of the citrus EO against microbial cultures revealed its activity in controlling and eradicating bacterial and fungal growth. Hydro distillation followed by enzyme treatment is a promising approach that combines two separate extraction procedures. The produced biopolymer showed the generation of electrical signals under minimal pressure and stretching and prevented microbial degeneration when applied to a nanogenerator.

Harnessing 3D Printing and Electrospinning for Multiscale Hybrid Patches Mimicking the Native Myocardium.

Engineered cardiac tissues show potential for regenerative therapy in ischemic heart disease. Yet, selection of soft biomaterials for scaffold manufacturing is primarily influenced by empirical and compositional factors, raising concerns about arrhythmic risks due to poor electrophysiological integration. Addressing this, we developed multiscale hybrid myocardial patches mimicking native myocardium's structural and biomechanical attributes, utilizing 3D printing and electrospinning techniques. We compared three patch types: pure silicone and silicone-poly(lactic-co-glycolic acid) (PLGA) with random (S-PLGA-R) and aligned (S-PLGA-A) fibers. S-PLGA-A patches with fiber orientation angles of 95-115° are achieved by applying a secondary electrical field using two parallel aluminum enhancers. With bulk and localized moduli of 350-750 and 13-20 kPa resembling the native myocardium, S-PLGA-A patches demonstrate a sarcomere length of 2.1 ± 0.2 μm, ≥50% higher strain motions and diastolic phase, and a 50-70% slower rise of calcium handling compared to the other two patches. This enhanced maturation and improved synchronization phenomena are attributed to efficient force transmission and reduced stress concentration due to mechanical similarity and linear propagation of electrical signals. This study presents a promising strategy for advancing regenerative cardiac therapies by harnessing the capabilities of 3D printing and electrospinning, providing a proof-of-concept for their effectiveness.

PVDF-HFP encapsulated WS2 nanosheets in droplet-based triboelectric nanogenerators for possible detection of human Na+/K+ ion concentration

Here we report the liquid–solid interaction in droplet-based triboelectric nanogenerators (TENG) for estimation of human Na+/K+ levels. The exploitation of PVDF-HFP encapsulated WS2 as active layer in the droplet-based TENG (DTENG) leads to the generation of electrical signal during the impact of water droplet. Comparison over the control devices indicates that surface quality and dielectric nature of the PVDF-HFP/WS2 composite largely dictates the performance of the DTENG. The demonstration of excellent sensitivity of the DTENG towards water quality indicates its promising application towards water testing. In addition, the alteration in output signal with slightest variation in ionic concentration (Na+ or K+) in water has been witnessed and is interpreted with charge transfer and ion transfer processes during liquid–solid interaction. The study reveals that the ion mobility largely affects the ion adsorption process on the active layer of PVDF-HFP/WS2 and thus generates distinct output profiles for diverse ions like Na+ and K+. Following that, the DTENG characteristics have been exploited to artificial urine where the varying output signals have been recorded for variation in urinary Na+ ion concentration. Therefore, the deployment of PVDF-HFP/WS2 in DTENG holds promising application towards the analyse of ionic characteristics of body fluids.

Stochastic electromechanical bidomain model *

We analyse a system of nonlinear stochastic partial differential equations (SPDEs) of mixed elliptic-parabolic type that models the propagation of electric signals and their effect on the deformation of cardiac tissue. The system governs the dynamics of ionic quantities, intra and extra-cellular potentials, and linearised elasticity equations. We introduce a framework called the active strain decomposition, which factors the material gradient of deformation into an active (electrophysiology-dependent) part and an elastic (passive) part, to capture the coupling between muscle contraction, biochemical reactions, and electric activity. Under the assumption of linearised elastic behaviour and a truncation of the nonlinear diffusivities, we propose a stochastic electromechanical bidomain model, and establish the existence of weak solutions for this model. To prove existence through the convergence of approximate solutions, we employ a stochastic compactness method in tandem with an auxiliary non-degenerate system and the Faedo–Galerkin method. We utilise a stochastic adaptation of de Rham’s theorem to deduce the weak convergence of the pressure approximations.

Nonlinear dynamic wave characteristics of optical soliton solutions in ion-acoustic wave

Traveling wave solutions are utilized to depict reaction-diffusion and analyze electrical signal transmission and propagation in space-time nonlinear fractional order partial differential equations like the space-time fractional Telegraph and Kolmogorov-Petrovsky Piskunov equations, and that are used in physical science to model combustion, biological research to model nerve impulse propagation, chemical dynamics to model concentration in order wave propagation, and plasma to model the progression of a set of duffing oscillators. In this study, the new generalized (G′/G)−expansion technique was employed to construct some novel and more universal closed-form traveling wave solutions in the sense of conformable derivatives which explain the above-stated phenomena properly. By utilizing complex fractional transformation, the ordinary differential equations are generated from fractional order differential equations. The recommended technique allowed us to produce some dynamical wave patterns of kink, single soliton, compacton, periodic shape, multiple periodic waves, anti-kink, and other structures are developed, which are shown using 3D plots and contour plots to illustrate the physical layout clearly. The traveling waveform responses can be defined in terms of functions based on trigonometry, hyperbolic operations, and rational functions and that are quick, flexible, and simple to reproduce. Furthermore, the obtained closed-form solutions for nonlinear fractional evolution equations make stability analysis and accuracy comparison amongst numerical solvers easier, which asserts that the new generalized (G′/G)−expansion technique is one of the most proficient and effective approaches.

Acquired control over proliferation and differentiation of ventricular cardiomyocytes to break down the mechanisms of cardiac repair

Abstract Funding Acknowledgements None. Loss of myocardial tissue remains a leading cause of morbidity and mortality by causing heart rhythm disturbances and heart failure. The (pre-)clinical effects of inducing cardiac regeneration by cardiac cell therapy have been disappointing. In order to find new curative options for these disabling cardiac diseases a shift of focus towards steering the heart to regenerate itself is needed. The aim of this study was to generate a robust ventricular cardiomyocyte model in which proliferation and differentiation could be tightly controlled to investigate cardiac regeneration. To accomplish this we have generated a line of immortalized neonatal rat ventricular cardiomyocytes (nrVMs) through expression of the cell cycle regulators cyclin-dependent kinase 4 and cyclin D1 (CDK4-D1). The CDK4-D1 expressing nrVMs were positive for the proliferation marker Ki67 in contrast to control nrVMs. Cardiomyogenic differentiation could still be induced after multiple passages (> passage 10) as evidenced by immunocytochemistry and optical voltage mapping. These contractile and excitable cells were indeed positive for the cardiac-specific sarcomeric proteins alpha actinin and troponin T in a sarcomeric pattern similar to native nrVMs. Passaging of the control nrVM cultures, however, ultimately led to a senescent cell population lacking sarcomeric markers after passage 3. Electrophysiological analysis of immortalized monolayers, after inducing cardiomyogenic differentiation, showed not only uniform propagation of electrical signal throughout the cultures, but also re-entrant activity although at low frequency. In conclusion, these data show that were able to immortalize ventricular cardiomyocytes by preserving their contractile and excitable phenotype upon significant expansion. Further optimisation of this model will lead to a research model of ventricular cardiomyocytes which will give us the opportunity to unravel the process of cardiomyogenesis and uncover mechanisms which could allow us to enhance the ability of the heart to regenerate itself.

Modeling Excitable Cells with Memristors

This paper presents an in-depth analysis of an excitable membrane of a biological system by proposing a novel approach that the cells of the excitable membrane can be modeled as the networks of memristors. We provide compelling evidence from the Chay neuron model that the state-independent mixed ion channel is a nonlinear resistor, while the state-dependent voltage-sensitive potassium ion channel and calcium-sensitive potassium ion channel function as generic memristors from the perspective of electrical circuit theory. The mechanisms that give rise to periodic oscillation, aperiodic (chaotic) oscillation, spikes, and bursting in an excitable cell are also analyzed via a small-signal model, a pole-zero diagram of admittance functions, local activity, the edge of chaos, and the Hopf bifurcation theorem. It is also proved that the zeros of the admittance functions are equivalent to the eigen values of the Jacobian matrix, and the presence of the positive real parts of the eigen values between the two bifurcation points lead to the generation of complicated electrical signals in an excitable membrane. The innovative concepts outlined in this paper pave the way for a deeper understanding of the dynamic behavior of excitable cells, offering potent tools for simulating and exploring the fundamental characteristics of biological neurons.

Analytical and numerical solutions to the Klein–Gordon model with cubic nonlinearity

In this paper, the nonlinear Klein–Gordon equation’s exact solutions are obtained through the application of an appropriate transformation based on He’s semi-inverse approach. This equation considered a generalization of other famous models in applied science, such as Phi-4 equation, Duffing equation, Fisher–Kolmogorov model through population dynamics and Hodgkin–Huxley equation that characterizes the propagation of electrical signals via nervous system. The suggested approach is simple, robust, and efficient, and its application in other partial differential equations in applied science seems promising. Numerical solution of the nonlinear Klein–Gordon equation is presented using finite difference method. The method’s accuracy is demonstrated by contrasting it with the exact solution that we obtained. The Von Neumann stability technique is applied to obtain the stability condition and a convergent test is presented Some 2D and 3D graphs matching to chosen solutions are simulated by taking into account appropriate values for the parameters.

Local field potential journey into the Basal Ganglia

Local field potentials (LFP) in the basal ganglia (BG) have attracted considerable research and clinical interest. The genesis of these signals has been a topic of extensive discourse, focusing on whether they are a manifestation of local synaptic activity or result from the propagation of electrical signals through tissue, as described by the Maxwell equations (volume conduction). To investigate this, we conducted simultaneous recordings of LFPs from two cortical areas— the dorsolateral prefrontal cortex (DLPFC) and the primary motor cortex (M1)—and various sites within the BG nuclei in an awake, non-task-engaged non-human primate (NHP). Employing innovative analytical techniques, we discerned significant cross-correlations indicative of potential connections, while filtering out non-significant correlations. This allowed us to differentiate between synaptic inputs and volume conduction. Our findings indicate two distinct propagation pathways of BG field potentials emanating from the M1 and the DLPFC, each characterized by different temporal delays. The results imply that these anatomical pathways are differentially influenced by the mechanisms of volume conduction and synaptic transmission. Notably, the M1 exhibits more functional links with non-zero-time delays to the BG structures, while the DLPFC-BG connections are marked by zero-time delays, suggesting a predominance of volume conduction effects. Consequently, investigations into the origins of BG LFP should account for the distinct anatomical pathways linking the cortex and the BG, as they differentially represent information flow and volume conductance.