Effects of 15 Hz square wave magnetic fields on the voltage-gated sodium and potassium channels in prefrontal cortex pyramidal neurons

Response of photosynthesis and electrical reactions of wheat plants upon the action of magnetic fields in the Schumann resonance frequency band

Alternating magnetic fields (MF) with Schumann resonance frequencies accompanied the development of living organisms throughout evolution, but today it remains unclear whether they can have a special biological effect in comparison with surrounding non-resonant frequencies. This work shows some stimulating effect of extremely low-frequency MFs on morphometric parameters and the activity of physiological processes in wheat (Triticum aestivum L.). It is shown that the MF effect is more pronounced for transient processes - photosynthesis reactions and changes in electrical potential caused by turning on light. For light-induced electrical reactions, the dependence of the severity of the effect on the frequency of the applied MF was demonstrated. It is shown that the most pronounced effect occurs in the 14.3 Hz field, which corresponds to the second harmonic of the Schumann resonance. The predominant sensitivity of signal-regulatory systems gives reason to assume the influence of MFs with Schumann resonance frequencies on the interaction of plants with environmental factors under conditions of a changed electromagnetic environment. Such conditions can occur, for example, with an increase in lightning activity caused by climate change, which serves as the basis for the generation of Schumann resonances, and with the development of artificial ecosystems outside the Earth's atmosphere.

Comparative analysis of energy transfer mechanisms for neural implants

As neural implant technologies advance rapidly, a nuanced understanding of their powering mechanisms becomes indispensable, especially given the long-term biocompatibility risks like oxidative stress and inflammation, which can be aggravated by recurrent surgeries, including battery replacements. This review delves into a comprehensive analysis, starting with biocompatibility considerations for both energy storage units and transfer methods. The review focuses on four main mechanisms for powering neural implants: Electromagnetic, Acoustic, Optical, and Direct Connection to the Body. Among these, Electromagnetic Methods include techniques such as Near-Field Communication (RF). Acoustic methods using high-frequency ultrasound offer advantages in power transmission efficiency and multi-node interrogation capabilities. Optical methods, although still in early development, show promising energy transmission efficiencies using Near-Infrared (NIR) light while avoiding electromagnetic interference. Direct connections, while efficient, pose substantial safety risks, including infection and micromotion disturbances within neural tissue. The review employs key metrics such as specific absorption rate (SAR) and energy transfer efficiency for a nuanced evaluation of these methods. It also discusses recent innovations like the Sectored-Multi Ring Ultrasonic Transducer (S-MRUT), Stentrode, and Neural Dust. Ultimately, this review aims to help researchers, clinicians, and engineers better understand the challenges of and potentially create new solutions for powering neural implants.

The increase in c-fos expression in epileptic seizures is inhibited by magnetic field application, but not KCa1.1 channel expression

The aim of this study was to understand the expression of big potassium (BK, KCa1.1) channels in epileptic seizures under magnetic field application. Forty Wistar albino adult male rats were divided into five groups (n = 8). First group rats were control group. Pentylenetetrazole (PTZ) administrated to second group rats to induce the seizures with 35 mg/kg intraperitoneally injection every two days. Levetiracetam (LEV) i.p. at a dose of 108 mg/kg was given to third group rats as positive control group (PC) before 20 minutes PTZ administration. Pulsed magnetic field with 1.5 mT was exposed to the fourth group rats for 3 hours a day for 1 month as magnetic field (MF) group. 1.5 mT pulsed magnetic field was exposed to the fifth group rats for 3 hours a day for 1 month in addition to PTZ administration (PTZ+MF). KCa1.1 not changed in hippocampus of PTZ rats while increased in frontal cortex and pons for PTZ group but not changed with magnetic field exposure. KCa1.1 increased in heart of PTZ animals and turned back to mean control values with magnetic field exposure. Suppressing the expected increase of c-fos protein expression in seizures with magnetic field application but not being able to change the KCa1.1 expression shows that new studies can be done by increasing the frequency of 1.5 mT magnetic field.

Assessing the combination of magnetic field stimulation, iron oxide nanoparticles, and aligned electrospun fibers for promoting neurite outgrowth from dorsal root ganglia in vitro

Magnetic fiber composites combining superparamagnetic iron oxide nanoparticles (SPIONs) and electrospun fibers have shown promise in tissue engineering fields. Controlled grafting of SPIONs to the fibers post-electrospinning generates biocompatible magnetic composites without altering desired fiber morphology. Here, for the first time, we assess the potential of SPION-grafted scaffolds combined with magnetic fields to promote neurite outgrowth by providing contact guidance from the aligned fibers and mechanical stimulation from the SPIONs in the magnetic field. Neurite outgrowth from primary rat dorsal root ganglia (DRG) was assessed from explants cultured on aligned control and SPION-grafted electrospun fibers as well as on non-grafted fibers with SPIONs dispersed in the culture media. To determine the optimal magnetic field stimulation to promote neurite outgrowth, we generated a static, alternating, and linearly moving magnet and simulated the magnetic flux density at different areas of the scaffold over time. The alternating magnetic field increased neurite length by 40% on control fibers compared to a static magnetic field. Additionally, stimulation with an alternating magnetic field resulted in a 30% increase in neurite length and 62% increase in neurite area on SPION-grafted fibers compared to DRG cultured on PLLA fibers with untethered SPIONs added to the culture media. These findings demonstrate that SPION-grafted fiber composites in combination with magnetic fields are more beneficial for stimulating neurite outgrowth on electrospun fibers than dispersed SPIONs. STATEMENT OF SIGNIFICANCE: Aligned electrospun fibers improve axonal regeneration by acting as a passive guidance cue but do not actively interact with cells, while magnetic nanoparticles can be remotely manipulated to interact with neurons and elicit neurite outgrowth. Here, for the first time, we examine the combination of magnetic fields, magnetic nanoparticles, and aligned electrospun fibers to enhance neurite outgrowth. We show an alternating magnetic field alone increases neurite outgrowth on aligned electrospun fibers. However, combining the alternating field with magnetic nanoparticle-grafted fibers does not affect neurite outgrowth compared to control fibers but improves outgrowth compared to freely dispersed magnetic nanoparticles. This study provides the groundwork for utilizing magnetic electrospun fibers and magnetic fields as a method for promoting axonal growth.

The Time-Dependence of Three Different Modes of ELF-EMF Stimulation on LTP at Schaffer Collateral-CA1 Synapses

Long-term potentiation (LTP) is considered the cellular basis of learning and memory. Extremely low-frequency electromagnetic fields (ELF-EMFs) are neuromodulation tools for regulating LTP. However, the temporal effects of short-term ELF-EMF stimulation on LTP are not yet known. In this study, we evaluated the time-dependent effects of 15 Hz/2 mT ELF-EMF stimulation on LTP at the Schaffer collateral-CA1 (SC-CA1) synapses in Sprague-Dawley rats. Hippocampal slices were exposed to three different modes of ELF-EMFs (sinusoidal, single-frequency pulse, and rhythm pulse) and durations (10, 20, 40, and 60 s). The baseline was recorded for 20 min and field excitatory postsynaptic potential (fEPSP) was recorded for 60 min using multi-electrode arrays (MEA) after plasticity induction using 100 Hz electrical high-frequency stimulation (HFS). Compared to the control group, the LTP decreased under three different magnetic fields and was proportional to time; that is, the longer the time, the greater the inhibition. We also compared the three magnetic fields and showed that the continuous sinusoidal magnetic field had the largest inhibitory rate of LTP, while pulsed and rhythm pulsed magnetic fields were similar. We showed that different modes of ELF-EMF stimulation had a time-dependent effect on LTP at Schaffer collateral-CA1 synapses, which provides experimental evidence for the treatment of related neurological diseases. © 2021 Bioelectromagnetics Society.

Brain-to-brain communication: the possible role of brain electromagnetic fields (As a Potential Hypothesis)

Up now, the communication between brains of different humans or animals has been confirmed and confined by the sensory medium and motor facilities of body. Recently, direct brain-to-brain communication (DBBC) outside the conventional five senses has been verified between animals and humans. Nevertheless, no empirical studies or serious discussion have been performed to elucidate the mechanism behind this process. The validation of DBBC has been documented via recording similar pattern of action potentials occurring in the brain cortex of two animals. With regard to action potentials in brain neurons, the magnetic field resulting from the action potentials created in neurons is one of the tools where the brain of one animal can affect the brain of another. It has been shown that different animals, even humans, have the power to understand the magnetic field. Cryptochrome, which exists in the retina and in different regions of the brain, has been confirmed to be able to perceive magnetic fields and convert magnetic fields to action potentials. Recently, iron particles (Fe₃O₄) believed to be functioning as magnets have been found in various parts of the brain, and are postulated as magnetic field receptors. Newly developed supersensitive magnetic sensors made of iron magnets that can sense the brain's magnetic field have suggested the idea that these Fe₃O₄ particles or magnets may be capable of perceiving the brain's extremely weak magnetic field. The present study suggests that it is possible the extremely week magnetic field in one animal's brain to transmit vital and accurate information to another animal's brain.

Effects of modulation on sodium and potassium channel currents by extremely low frequency electromagnetic fields stimulation on hippocampal CA1 pyramidal cells

To investigate the effects of extremely low-frequency electromagnetic fields (ELF-EMFs) stimulation on sodium channel currents (I_Na), transient outward potassium channel currents (I_A) and delayed rectifier potassium channel currents (I_K) on hippocampal CA1 pyramidal neurons of young Sprague-Dawley rats. CA1 pyramidal neurons of rat hippocampal slices were subjected to ELF-EMFs stimulation with different frequencies (15 and 50 Hz), intensities (0.5, 1 and 2 mT) and durations (10, 20 and 30 min). The I_Na, I_A and I_K of neurons were recorded by a whole-cell patch-clamp method. ELF-EMFs stimulation enhanced I_Na densities, and depressed I_A and I_K densities. In detail, I_Na was more sensitive to the variation of intensities and frequencies of ELF-EMFs, whereas I_A and I_K were mainly affected by the variation of the duration of ELF-EMFs. ELF-EMFs stimulation altered activation and deactivation properties of I_Na, I_A and I_K. ELF-EMFs stimulation plays a role as a regulator rather than an inducer for ion channels. It might change the transition probability of ion channel opening or closing, and might also change the structure and function of the ion channel which need to be proved by the further technical method.