Electrophysiological Methods Research Articles

Structural epilepsy: current state of the problem

This review emphasizes modern conceptions in the fundamental and clinical aspects of structural epilepsy. Highly informative neuroimaging, electrophysiological and pathomorphological diagnostic methods contribution to the study of this problem is noted. Current understanding of the pathogenesis and clinical picture of the most common types of drug resistant epilepsy are presented: hippocampal sclerosis, focal cortical dysplasia and their surgical correction methods. We considered perspective directions of fundamental clinical and experimental research, focusing on the study of epileptogenesis mechanisms and developing effective methods for prevention and treatment.

Berberine ameliorates inflammation by inhibiting MrgprB2 receptor-mediated activation of mast cell in mice

BackgroundBerberine, an isoquinoline alkaloid, is known for anti-inflammatory activities. However, the research on the anti-inflammatory mechanism of berberine is not comprehensive. Recently, studies have shown that MrgprB2 (Mas-related G-protein-coupled receptor B2) in mice and MrgprX2 (Mas-related G-protein-coupled receptor X2) in humans play vital roles in inflammation. Therefore, this study aims to investigate whether the anti-inflammatory activity of berberine is related to MrgprB2 receptor. MethodsThe anti-inflammatory activity of BH (berberine hydrochloride) was evaluated by hindpaw edema analysis, pathological analysis and RT-qPCR. Transgenic mice (MrgprB2−/− mice), HEK293T cell transfection, calcium imaging, electrophysiology, molecular docking and other methods were employed to investigate the potential relationship between the anti-inflammatory activity of BH and the MrgprB2 receptor. ResultsThe results demonstrated that BH significantly alleviated C48/80 (compound 48/80)-induced local inflammation in vivo. This was evidenced by a decrease in paw edema, reduced infiltration of inflammatory cells, inhibition of mast cell activation, and down-regulation of inflammatory factors such as CXCL13 (CXC subfamily 13) and TNF-α (tumor necrosis factor-α). It was also found that knockout of MrgprB2 receptor could block the anti-inflammatory activity of BH in mice. Furthermore, calcium imaging revealed that BH effectively inhibited the activity of MrgprB2 receptor in overexpressed HEK293T cells in vitro. Additionally, it was observed that BH also inhibited MrgprB2-mediated voltage-dependent current changes in mouse peritoneal mast cells. Molecular docking results further indicated that BH had affinity with MrgprX2 protein. ConclusionsThe anti-inflammatory mechanism of BH may be partially attributed to the inhibition of MrgprB2 receptor-mediated mast cell activation.

Integration of single-photon miniature fluorescence microscopy and electrophysiological recording methods for <i>in vivo</i> studying hippocampal neuronal activity

The miniature single-photon fluorescent microscope (miniscope) enables the visualization of calcium activity in vivo in freely moving laboratory animals, providing the capability to track cellular activity during the investigation of memory formation, learning, sleep, and social interactions. However, the use of calcium sensors for in vivo imaging is limited by their relatively slow (millisecond-scale) kinetics, which complicates the recording of high-frequency spike activity. The integration of methods from single-photon miniature fluorescent microscopy with electrophysiological recording, which possesses microsecond resolution, represents a potential solution to this issue. Such a combination of techniques allows for the simultaneous recording of optical and electrophysiological activity in a single animal in vivo. In this study, a flexible polyimide microelectrode was developed and integrated with the gradient lens of the miniscope. The in vivo tests conducted in this research confirmed that the microelectrode combined with the gradient lens facilitates simultaneous single-photon calcium imaging and local field potential recording in the hippocampus of an adult mouse.

Ionotropic Receptor 8a (Ir8a) Plays an Important Role in Acetic Acid Perception in the Oriental Fruit Fly, Bactrocera dorsalis.

Bactrocera dorsalis is one of the major invasive pests worldwide. The acetic acid-enriched sweet bait trapping is an important method for monitoring and controlling this fly. Several studies showed that acetic acid is perceived by ionotropic receptors (IRs). Thus, we annotated 65 IR genes in the B. dorsalis genome. We also investigated the IRs involved in acetic acid perception in this fly by behavioral, electrophysiological, and molecular methods. As the results indicated, the antennae are the main olfactory organs to sense acetic acid. Among the antennal IRs showed acetic acid-induced expression profiles, IR8a was proven to perceive acetic acid by CRISPR/Cas9-mediated mutagenesis. Additionally, calcium imaging showed that IR64a and IR75a are potential acetic acid receptors respectively co-expressed with IR76b and IR8a. This study represents the first comprehensive characterization of IRs in B. dorsalis at the whole-genome level, revealing the significant role of IRs in acetic acid perception.

Characterization of the cellular components of mouse collecting lymphatic vessels reveals that lymphatic muscle cells are the innate pacemaker cells regulating lymphatic contractions.

Collecting lymphatic vessels (cLVs) exhibit spontaneous contractions with a pressure-dependent frequency, but the identity of the lymphatic pacemaker cell is still debated. By analogy to pacemakers in the GI and lower urinary tracts, proposed cLV pacemaker cells include interstitial cells of Cajal like cells (ICLC) or the lymphatic muscle (LMCs) cells themselves. Here we combined immunofluorescence and scRNAseq analyses with electrophysiological methods to examine the cellular constituents of the mouse cLV wall and assess whether any cell type exhibited morphological and functional processes characteristic of pacemaker cells: a continuous if not contiguous network integrated into the electrical syncytium; spontaneous Ca2+ transients; and depolarization-induced propagated contractions. We employed inducible Cre (iCre) mouse models routinely used to target these specific cell populations including: c-kitCreER T2 to target ICLC; PdgfrβCreER T2 to target pericyte-like cells; PdgfrαCreER ™ to target CD34+ adventitial cells and ICLC; and Myh11CreER T2 to target LMCs directly. These specific inducible Cre lines were crossed to the fluorescent reporter ROSA26mT/mG, the genetically encoded Ca2+ sensor GCaMP6f, and the light-activated cation channel rhodopsin2 (ChR2). c-KitCreER T2 labeled both a sparse population of LECs and round adventitial cells that responded to the mast cell activator compound 48-80. PdgfrβCreER T2 drove recombination in both adventitial cells and LMCs, limiting its power to discriminate a pericyte-specific population. PdgfrαCreER ™ labeled a large population of interconnected, oak leaf-shaped cells primarily along the adventitial surface of the vessel. Of these cells, only LMCs consistently, but heterogeneously, displayed spontaneous Ca2+ events during the diastolic period of the contraction cycle, and whose frequency was modulated in a pressure-dependent manner. Optogenetic depolarization through the expression of ChR2 under control of Myh11CreER T2 , but not PdgfrαCreER ™ or c-KitCreER T2 , resulted in propagated contractions upon photo-stimulation. Membrane potential recordings in LMCs demonstrated that the rate of diastolic depolarization significantly correlated with contraction frequency. These findings support the conclusion that LMCs, or a subset of LMCs, are responsible for mouse cLV pacemaking.

Problems in the Diagnosis of Dysfunctions of the Olfactory Analyzer in Laboratory Animals Based on Behavioral and Electrophysiological Study Methods

Problems in the Diagnosis of Dysfunctions of the Olfactory Analyzer in Laboratory Animals Based on Behavioral and Electrophysiological Study Methods

Stress resilience is an active and multifactorial process manifested by structural, functional, and molecular changes in synapses

Stress resilience is the ability of neuronal networks to maintain their function despite the stress exposure. Using a mouse model we here investigate stress resilience phenomenon. To assess the resilient and anhedonic behavioral phenotypes developed after the induction of chronic unpredictable stress, we quantitatively characterized the structural and functional plasticity of excitatory synapses in the hippocampus using a combination of proteomic, electrophysiological, and imaging methods. Our results indicate that stress resilience is an active and multifactorial process manifested by structural, functional, and molecular changes in synapses. We reveal that chronic stress influences palmitoylation of synaptic proteins, whose profiles differ between resilient and anhedonic animals. The changes in palmitoylation are predominantly related with the glutamate receptor signaling thus affects synaptic transmission and associated structures of dendritic spines. We show that stress resilience is associated with structural compensatory plasticity of the postsynaptic parts of synapses in CA1 subfield of the hippocampus.

Development of a digital amplifier system for cut-open oocyte electrophysiology

The cut-open oocyte Vaseline gap (COVG) technique is a powerful electrophysiological method for the characterization of ion channels. However, traditional amplifiers for COVG are labor-intensive and require significant user expertise. We introduce an innovative, open-source digital amplifier system with high-speed digitization and software-controlled electronics for computer-driven automation. This system compares well to existing commercial systems in terms of conventional specifications of step response (current peak at 25°μs and decay of 36°μstime constant), current noise (1.0 nA at 3 kHz bandwidth), and dynamic range (96.9 dB). Additionally, it unlocks new methods through close integration of the amplifier and software, including machine learning techniques for tuning capacitive compensation waveforms, achieving a 100-fold suppression of mean-squared transient current, and impedance measurement methods to identify system components such as membrane capacitance and electrode resistances. For future extensions, the design has unique attributes such as real-time digital signal processing for feedback; multiple-input and multiple-output; and allows for user customization. By providing open-source access to the circuit board designs, control software, and FPGA code on GitHub, this approach aims to foster cross-disciplinary collaboration and facilitate instrument customization enabling previously inaccessible electrophysiology experiments.

Surgical Treatment of Spinal Intra-Extradural Meningioma: A Clinical Case

Spinal meningiomas are rare, predominantly benign tumors that exhibit slow growth and typically have a non-invasive pattern of development. They originate from arachnoid cells and fibroblasts of the dura mater. Despite their benign nature, some meningiomas can exhibit intra-extradural extension, complicating both diagnosis and treatment. This article presents a clinical case involving a patient with an intra-extradural spinal meningioma. Despite radiological imaging suggesting a neurinoma, the final diagnosis confirmed a meningioma. Case Report: A female patient underwent surgical tumor resection through a posterolateral approach with laminectomy and facetectomy at the C4-C5 vertebral levels. The tumor, extending through the intervertebral foramen, was completely resected along with the affected nerve root. Histological examination verified a Grade II meningioma. Discussion: Despite advancements in neuroimaging and surgical techniques, intraoperative findings can be unpredictable, necessitating an adaptive approach to tumor resection. The article emphasizes the importance of adequate preoperative planning and the use of intraoperative neurophysiological monitoring to reduce the risk of complications and improve treatment outcomes. Conclusions: The primary treatment for spinal meningiomas is surgical. For dorsal and lateral localizations, total resection with the involved dura mater (Simpson Grade I) is optimal. For ventral localizations, tumor resection with coagulation of the dural attachment site (Simpson Grade II) is preferred. Preoperative and intraoperative use of electrophysiological methods is recommended to assess the functional status of neural structures. Intra-extradural localization of meningiomas is rare and presents significant challenges in preoperative diagnosis, requiring specific skills for effective removal.

Assessment of ventricular electrical heterogeneity in left bundle branch pacing and left ventricular septal pacing by using various electrophysiological methods.

Left bundle branch area pacing (LBBAP) comprises pacing at the left ventricular septum (LVSP) or left bundle branch (LBBP). The aim of the present study was to investigate the differences in ventricular electrical heterogeneity between LVSP, LBBP, right ventricular pacing (RVP) and intrinsic conduction with different dyssynchrony measures using the ECG, vectorcardiograpy, ECG belt, and Ultrahigh frequency (UHF-)ECG. Thirty-seven patients with a pacemaker indication for bradycardia or cardiac resynchronization therapy underwent LBBAP implantation. ECG, vectorcardiogram, ECG belt and UHF-ECG signals were recorded during RVP, LVSP and LBBP, and intrinsic activation. QRS duration (QRSd) was measured from the ECG, QRS area was calculated from the vectorcardiogram, LV activation time (LVAT) and standard deviation of activation time (SDAT) from ECG belt and electrical dyssynchrony (e-DYS16) from UHF-ECG. Both LVSP and LBBP significantly reduced ventricular electrical heterogeneity as compared to underlying LBBB and RV pacing in terms of QRS area (p < .001), SDAT (p < .001), LVAT (p < .001) and e-DYS16 (p < .001). QRSd was only reduced as compared to RV pacing(p < .001). QRS area was similar during LBBP and normal intrinsic conduction, e-DYS16 was similar during LVSP and normal intrinsic conduction, whereas SDAT was similar for LVSP, LBBP and normal intrinsic conduction. For all these variables there was no significant difference between LVSP and LBBP. Both LVSP and LBBP resulted in a more synchronous LV activation than LBBB and RVP. Especially LBBP resulted in levels of LV synchrony comparable to normal intrinsic conduction.

Revealing a hidden conducting state by manipulating the intracellular domains in KV10.1 exposes the coupling between two gating mechanisms.

The KCNH family of potassium channels serves relevant physiological functions in both excitable and non-excitable cells, reflected in the massive consequences of mutations or pharmacological manipulation of their function. This group of channels shares structural homology with other voltage-gated K+ channels, but the mechanisms of gating in this family show significant differences with respect to the canonical electromechanical coupling in these molecules. In particular, the large intracellular domains of KCNH channels play a crucial role in gating that is still only partly understood. Using KCNH1(KV10.1) as a model, we have characterized the behavior of a series of modified channels that could not be explained by the current models. With electrophysiological and biochemical methods combined with mathematical modeling, we show that the uncovering of an open state can explain the behavior of the mutants. This open state, which is not detectable in wild-type channels, appears to lack the rapid flicker block of the conventional open state. Because it is accessed from deep closed states, it elucidates intermediate gating events well ahead of channel opening in the wild type. This allowed us to study gating steps prior to opening, which, for example, explain the mechanism of gating inhibition by Ca2+-Calmodulin and generate a model that describes the characteristic features of KCNH channels gating.

Epilepsy Research in the Institute of Physiology of the Czech Academy of Sciences in Prague.

Starting from simple clinical statistics, the spectrum of methods used in epilepsy research in the Institute of Physiology of the Czechoslovak (now Czech) Academy of Sciences progressively increased. Professor Servít used electrophysiological methods for study of brain activity in lower vertebrates, neuropathology was focused on electronmicroscopic study of cortical epileptic focus and ion-sensitive microelectrodes were used for studies of cortical direct current potentials. Developmental studies used electrophysiological methods (activity and projection of cortical epileptic foci, EEG under the influence of convulsant drugs, hippocampal, thalamic and cortical electrical stimulation for induction of epileptic afterdischarges and postictal period). Extensive pharmacological studies used seizures elicited by convulsant drugs (at first pentylenetetrazol but also other GABA antagonists as well as agonists of glutamate receptors). Motor performance and behavior were also studied during brain maturation. The last but not least molecular biology was included into the spectrum of methods. Many original data were published making a background of position of our laboratory in the first line of laboratories interested in brain development.

Electrophysiology in the language classroom

Using electrophysiological methods, Second Language Acquisition researchers have uncovered significant information about the neural correlates of late-learned additional language (L2) processing. An overarching question in much of this research is whether L2 learners show ‘nativelike’ event-related potential (ERP) patterns for grammar and semantic processing. The conclusions from early work on this question indicated that L2 ERP patterns can change qualitatively over time, for example as L2 proficiency increases, and that L2 learners do tend to show ‘nativelike’ ERP responses for some linguistic structures, particularly at higher proficiency. Certainly, whether L2 learners can achieve native speaker-like processing and behaviour has implications for the L2 classroom. This paper presents a review of L2 ERP individual differences research on grammar and semantic processing and highlights implications for L2 research and teaching. We focus the review on recent work that has examined individual differences in L2 ERPs, an area of research that may be especially fruitful for advancing knowledge of L2 neurocognition in classroom learners.

Simultaneous optical imaging of gastric slow waves and contractions in the in vivo porcine stomach.

Gastric peristalsis is governed by electrical "slow waves" generally assumed to travel from proximal to distal stomach (antegrade propagation) in symmetric rings. Although alternative slow-wave patterns have been correlated with gastric disorders, their mechanisms and how they alter contractions remain understudied. Optical electromechanical mapping, a developing field in cardiac electrophysiology, images electrical and mechanical physiology simultaneously. Here, we translate this technology to the in vivo porcine stomach. Stomachs were surgically exposed and a fluorescent dye (di-4-ANEQ(F)PTEA) that transduces the membrane potential (Vm) was injected through the right gastroepiploic artery. Fluorescence was excited by LEDs and imaged with one or two 256 × 256 pixel cameras. Motion artifact was corrected using a marker-based motion-tracking method and excitation ratiometry, which cancels common-mode artifact. Tracking marker displacement also enabled gastric deformation to be measured. We validated detection of electrical activation and Vm morphology against alternative nonoptical technologies. Nonantegrade slow waves and propagation direction differences between the anterior and posterior stomach were commonly present in our data. However, sham experiments suggest they were a feature of the animal preparation and not an artifact of optical mapping. In experiments to demonstrate the method's capabilities, we found that repolarization did not always follow at a fixed time behind activation "wavefronts," which could be a factor in dysrhythmia. Contraction strength and the latency between electrical activation and contraction differed between antegrade and nonantegrade propagation. In conclusion, optical electromechanical mapping, which simultaneously images electrical and mechanical activity, enables novel questions regarding normal and abnormal gastric physiology to be explored.NEW & NOTEWORTHY This article introduces a novel method for imaging gastric electrophysiology and mechanical function simultaneously in anesthetized, open-abdomen pigs. We demonstrate it by observing propagating slow-wave depolarization and repolarization along with the strength, spatial distribution, and direction of contractions. In addition, we observe that in this animal preparation, slow waves often do not propagate from the proximal to distal stomach and are frequently asymmetric between the anterior and posterior sides of the stomach.

Patricia Goldman-Rakic: A Pioneer in Cognitive Neuroscience.

Patricia Goldman-Rakic (1937-2003) was a trailblazing neuroscientist whose groundbreaking work greatly advanced our understanding of the prefrontal cortex and its crucial role in higher cognitive functions like working memory and executive function. Her innovative research, which integrated anatomical, electrophysiological, and behavioral methods, provided foundational insights into the neural basis of cognition. This review underscores her significant contributions, personal challenges, and the enduring influence of her work in the field of neuroscience.

Turning a Kv channel into hot and cold receptor by perturbing its electromechanical coupling.

Voltage-dependent potassium channels (Kv) are extremely sensitive to membrane voltage and play a crucial role in membrane repolarization during action potentials. Kv channels undergo voltage-dependent transitions between closed states before opening. Despite all we have learned using electrophysiological methods and structural studies, we still lack a detailed picture of the energetics of the activation process. We show here that even a single mutation can drastically modify the temperature response of the Shaker Kv channel. Using rapid cell membrane temperature steps (Tsteps), we explored the effects of temperature on the ILT mutant (V369I, I372L, and S376T) and the I384N mutant. The ILT mutant produces a significant separation between the transitions of the voltage sensor domain (VSD) activation and the I384N uncouples its movement from the opening of the domain (PD). ILT and I384N respond to temperature in drastically different ways. In ILT, temperature facilitates the opening of the channel akin to a "hot" receptor, reflecting the temperature dependence of the voltage sensor's last transition and facilitating VSD to PD coupling (electromechanical coupling). In I384N, temperature stabilizes the channel closed configuration analogous to a "cold" receptor. Since I384N drastically uncouples the VSD from the pore opening, we reveal the intrinsic temperature dependence of the PD itself. Here, we propose that the electromechanical coupling has either a "loose" or "tight" conformation. In the loose conformation, the movement of the VSD is necessary but not sufficient to efficiently propagate the electromechanical energy to the S6 gate. In the tight conformation the VSD activation is more effectively translated into the opening of the PD. This conformational switch can be tuned by temperature and modifications of the S4 and S4-S5 linker. Our results show that we can modulate the temperature dependence of Kv channels by affecting its electromechanical coupling.

Monitoring Leucine-Rich Repeat Containing 8 Channel (LRRC8/VRAC) Activity using Sensitized-Emission Förster Resonance Energy Transfer (SE-FRET).

Members of the LRRC8 protein family form heteromeric ion and osmolyte channels with roles in numerous physiological processes. As volume-regulated anion channels (VRACs)/volume-sensitive outwardly rectifying channels (VSORs), they are activated upon osmotic cell swelling and mediate the extrusion of chloride and organic osmolytes, leading to the efflux of water and hence cell shrinkage. Beyond their role in osmotic volume regulation, VRACs have been implicated in cellular processes such as differentiation, migration, and apoptosis. Through their effect on membrane potential and their transport of various signaling molecules, leucine-rich repeat containing 8 (LRRC8) channels play roles in neuron-glia communication, insulin secretion, and immune response. The activation mechanism has remained elusive. LRRC8 channels, like other ion channels, are typically studied using electrophysiological methods. Here, we describe a method to detect LRRC8 channel activation by measuring intra-complex sensitized-emission Förster resonance energy transfer (SE-FRET) between fluorescent proteins fused to the C-terminal leucine-rich repeat domains of LRRC8 subunits. This method offers the possibility to study channel activation in situ without exchange of the cytosolic environment and during processes such as cell differentiation and apoptosis.

Examination of Subclinical Neurological Involvement in Patients with Psoriasis Vulgaris

Background : The aim of this study is to evaluate cognitive functions of patients with psoriasis in terms of subclinical neurological involvement using p300 method, and to reveal the correlation between the disease duration and severity if any. Methods: 40 patients with psoriasis vulgaris and 40 healthy individuals were included in the study. Standard mini mental test and beck depression inventory were applied to the groups. PASI values and DLQI values of psoriasis patients were calculated. P300 measurements of both groups were recorded and assessed in order to evaluate the cognitive functions. Results: There was no statistically significant difference between the healthy and psoriasis groups in terms of PzLat, PzAmp, CzLat and CzAmp values (p=0.681, p=0.301, p=0.138, p=0.739, respectively). When it was compared in terms of PASI values, there was no statistically significant difference in the patient group in terms of PzLat, PzAmp, CzLat and CzAmp values (p=0.211, p=0.422, p=0.106, p=0.305, respectively). When evaluated according to disease duration, there was no statistically significant difference between the groups in terms of PzLat, PzAmp, CzLat and CzAmp values (p=0.901, p=0.244, p=0.632, p=0.868, respectively). Conclusion: Cognitive functions in psoriasis patients are not affected by the presence, severity and duration of the disease. As far as we know, the present study is the first study using electrophysiological P300 method in evaluating the cognitive functions in patients with psoriasis.

ELEKTROFIZJOLOGICZNE POMIARY UPOŚLEDZENIA SŁUCHU U NARAŻONYCH NA HAŁAS ŻOŁNIERZY ZE SŁUCHEM W NORMIE

IntroductionSome electrophysiological changes can occur in the auditory system in response to noise exposure with or without any permanent auditory threshold shift. The purpose of this study was to identify and measure cochlear function after noise exposure in individuals with normal hearing according to standard audiometric thresholds.Material and methodsPure tone audiometry (PTA) over the standard 0.250–8 kHz range and at 12 kHz, as well as distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) testing, were performed on 42 soldiers who had participated in combat. A control group of 40 participants underwent the same tests.ResultsIn the noise-exposed group, significantly poorer PTA thresholds were recorded at 12 kHz. DPOAE levels were significantly low only at 4 kHz. On ABR testing, both wave I and wave V demonstrated a significant decrease in amplitude and a significant increase in latency for the noise-exposed group.ConclusionsOur findings reveal that high levels of noise can not only damage outer hair cells but also cause changes at the level of the synapses (synaptopathy) which are not evident using standard PTA tests. However, electrophysiological methods can detect some changes in cochlear function.

Prospects of Electrocorticography in Neuropharmacological Studies in Small Laboratory Animals.

Electrophysiological methods of research are widely used in neurobiology. To assess the bioelectrical activity of the brain in small laboratory animals, electrocorticography (ECoG) is most often used, which allows the recording of signals directly from the cerebral cortex. To date, a number of methodological approaches to the manufacture and implantation of ECoG electrodes have been proposed, the complexity of which is determined by experimental tasks and logistical capabilities. Existing methods for analyzing bioelectrical signals are used to assess the functional state of the nervous system in test animals, as well as to identify correlates of pathological changes or pharmacological effects. The review presents current areas of applications of ECoG in neuropharmacological studies in small laboratory animals. Traditionally, this method is actively used to study the antiepileptic activity of new molecules. However, the possibility of using ECoG to assess the neuroprotective activity of drugs in models of traumatic, vascular, metabolic, or neurodegenerative CNS damage remains clearly underestimated. Despite the fact that ECoG has a number of disadvantages and methodological difficulties, the recorded data can be a useful addition to traditional molecular and behavioral research methods. An analysis of the works in recent years indicates a growing interest in the method as a tool for assessing the pharmacological activity of psychoactive drugs, especially in combination with classification and prediction algorithms.