Statistical Optimizations of Muscle Action Potentials Based on Modeling and Analysis of Ion Channel Dynamics

An Electromyogram (EMG) is an electrical signal, which is measured from a skeletal muscle during voluntary and involuntary contractions. EMGs are useful in interpreting pathological states of the musculoskeletal system. In particular, EMGs offer valuable information concerning the timing of muscular activity and its relative intensity. Various EMG models have developed with many different purposes from a pure mathematical model to a pattern structure model [17,46]. Sophisticated EMG models are necessary to examine the effects of small changes in muscular morphology and activities [46]. Due to the crucial importance of EMG models, all factors in the model should be precise and accurate. Especially, an intracellular action potential (IAP) model, the starting point of an EMG model, should be precisely generated because of its importance as the main component for an EMG model. Generally, the Rosenfalck IAP model [75,89] has been used because of its computational simplicity [59,72,77]. However, the Rosenfalck IAP model oversimplifies a real IAP, which has been experimentally measured, and it results in mismatching amplitudes and time duration between a real and modeled IAP. This research proposes a mathematical IAP model using a series of modified gamma and erlang probability density functions. The optimization of the proposed IAP model was conducted by several different numerical methods, namely Gauss-Newton, Steepest Descent, and Conjugate Gradient methods. These optimizing methods for the proposed muscle IAP model were validated by applying them to the experimental results of the Hudgkin and Huxley neuron action potential [11]. Due to the similarity in the mechanism of both nerve and muscle IAP generations, the validation shows that the methods and results are reasonably applied and obtained in the proposed muscle model, which for the first time incorporates properties that explain ion channel behavior in IAP generation

Cerebellar cortex granular layer interneurons in the macaque monkey are functionally driven by mossy fiber pathways through net excitation or inhibition

The granular layer is the input layer of the cerebellar cortex. It receives information through mossy fibers, which contact local granular layer interneurons (GLIs) and granular layer output neurons (granule cells). GLIs provide one of the first signal processing stages in the cerebellar cortex by exciting or inhibiting granule cells. Despite the importance of this early processing stage for later cerebellar computations, the responses of GLIs and the functional connections of mossy fibers with GLIs in awake animals are poorly understood. Here, we recorded GLIs and mossy fibers in the macaque ventral-paraflocculus (VPFL) during oculomotor tasks, providing the first full inventory of GLI responses in the VPFL of awake primates. We found that while mossy fiber responses are characterized by a linear monotonic relationship between firing rate and eye position, GLIs show complex response profiles characterized by "eye position fields" and single or double directional tunings. For the majority of GLIs, prominent features of their responses can be explained by assuming that a single GLI receives inputs from mossy fibers with similar or opposite directional preferences, and that these mossy fiber inputs influence GLI discharge through net excitatory or inhibitory pathways. Importantly, GLIs receiving mossy fiber inputs through these putative excitatory and inhibitory pathways show different firing properties, suggesting that they indeed correspond to two distinct classes of interneurons. We propose a new interpretation of the information flow through the cerebellar cortex granular layer, in which mossy fiber input patterns drive the responses of GLIs not only through excitatory but also through net inhibitory pathways, and that excited and inhibited GLIs can be identified based on their responses and their intrinsic properties

The Macaque Cerebellar Flocculus Outputs a Forward Model of Eye Movement

The central nervous system (CNS) achieves fine motor control by generating predictions of the consequences of the motor command, often called forward models of the movement. These predictions are used centrally to detect not-self generated sensations, to modify ongoing movements, and to induce motor learning. However, finding a neuronal correlate of forward models has proven difficult. In the oculomotor system, we can identify neuronal correlates of forward models vs. neuronal correlates of motor commands by examining neuronal responses during smooth pursuit at eccentric eye positions. During pursuit, torsional eye movement information is not present in the motor command, but it is generated by the mechanic of the orbit. Importantly, the directionality and approximate magnitude of torsional eye movement follow the half angle rule. We use this rule to investigate the role of the cerebellar flocculus complex (FL, flocculus and ventral paraflocculus) in the generation of forward models of the eye. We found that mossy fibers (input elements to the FL) did not change their response to pursuit with eccentricity. Thus, they do not carry torsional eye movement information. However, vertical Purkinje cells (PCs; output elements of the FL) showed a preference for counter-clockwise (CCW) eye velocity [corresponding to extorsion (outward rotation) of the ipsilateral eye]. We hypothesize that FL computes an estimate of torsional eye movement since torsion is present in PCs but not in mossy fibers. Overall, our results add to those of other laboratories in supporting the existence in the CNS of a predictive signal constructed from motor command information

Towards maximized volumetric capacity via pore-coordinated design for large-volume-change lithium-ion battery anodes

To achieve the urgent requirement for high volumetric energy density in lithium-ion batteries, alloy-based anodes have been spotlighted as next-generation alternatives. Nonetheless, for the veritable accomplishment with regards to high-energy demand, alloy-based anodes must be evaluated considering several crucial factors that determine volumetric capacity. In particular, the electrode swelling upon cycling must be contemplated if these anodes are to replace conventional graphite anodes in terms of volumetric capacity. Herein, we propose macropore-coordinated graphite-silicon composite by incorporating simulation and mathematical calculation of numerical values from experimental data. This unique structure exhibits minimized electrode swelling comparable to conventional graphite under industrial electrode fabrication conditions. Consequently, this hybrid anode, even with high specific capacity (527 mAh g(-1)) and initial coulombic efficiency (93%) in half-cell, achieves higher volumetric capacity (493.9 mAh cm(-3)) and energy density (1825.7 Wh L-1) than conventional graphite (361.4 mAh cm(-3) and 1376.3 Wh L-1) after 100 cycles in the full-cell configuration

Low-Dose Radiation-Induced Effects on Cognitive Function

The relation between the low-dose radiation and the cognitive decline remains limited and controversial. However, the increasing use of high-dose radiation for medical purposes and some historical radiation-related accidents indicated that the low-dose radiation reduced cognitive ability, suggesting the reconsideration of the central nervous system’s low sensitivity to radiation, which has been advocated by conventional radiation biology. Although the continuous stimulation of low-dose radiation is known to be an environmental stressor that causes a critical decline in cognition during space exploration, the overall mechanisms from radiation exposure to cognitive alteration is still lacking. One of its main reasons is the inconsistent empirical results, and there are various possibilities to cause the contradictory consequences, such as the hormesis effect of low-dose radiation, the cellular adaptive responses, the radiation resistance, the bystander effects, and the genomic instability. In this review, we survey the low-dose radiation-induced cognitive studies, targeting learning achievement, emotional changes as well as fundamental cognitive behaviors in both humans and animals. Also, some relevant molecular studies are reappraised to understand the low-dose radiation-induced effects on the cognitive function

Repeated Galvanic Vestibular Stimulation Modified the Neuronal Potential in the Vestibular Nucleus

Vestibular nucleus (VN) and cerebellar flocculus are known as the core candidates for the neuroplasticity of vestibular system. However, it has been still elusive how to induce the artificial neuroplasticity, especially caused by an electrical stimulation, and assess the neuronal information related with the plasticity. To understand the electrically induced neuroplasticity, the neuronal potentials in VN responding to the repeated electrical stimuli were examined. Galvanic vestibular stimulation (GVS) was applied to excite the neurons in VN, and their activities were measured by an extracellular neural recording technique. Thirty-eight neuronal responses (17 for the regular and 21 for irregular neurons) were recorded and examined the potentials before and after stimulation. Two-third of the population (63.2%, 24/38) modified the potentials under the GVS repetition before stimulation (p=0.037), and more than half of the population (21/38, 55.3%) changed the potentials after stimulation (p=0.209). On the other hand, the plasticity-related neuronal modulation was hardly observed in the temporal responses of the neurons. The modification of the active glutamate receptors was also investigated to see if the repeated stimulation changed the number of both types of glutamate receptors, and the results showed that AMPA and NMDA receptors decreased after the repeated stimuli by 28.32 and 16.09%, respectively, implying the modification in the neuronal amplitudes

An Empirical Muscle Intracellular Action Potential Model with Multiple Erlang probability Density Functions based on a Modified Newton Method

The convolution of the transmembrane current of an excitable cell and a weighting function generates a single fiber action potential (SFAP) model by using the volume conductor theory. Here, we propose an empirical muscle IAP model with multiple Erlang probability density functions (PDFs) based on a modified Newton method. In addition, we generate SFAPs based on our IAP model and referent sources, and use the peak-to-peak ratios (PPRs) of SFAPs for model verification. Through this verification, we find that the relation between an IAP profile and the PPR of its SFAP is consistent with some previous studies, and our IAP model shows close profiles to the referent sources. Moreover, we simulate and discuss some possible ionic activities by using the Erlang PDFs in our IAP model, which might present the underlying activities of ions or their channels during an IAP

Unveiling the Catalytic Origin of Nanocrystalline Yttrium Ruthenate Pyrochlore as a Bifunctional Electrocatalyst for Zn-Air Batteries

Zn-air batteries suffer from the slow kinetics of oxygen reduction reaction (ORR) and/or oxygen evolution reaction (OER). Thus, the bifunctional electrocatalysts are required for the practical application of rechargeable Zn-air batteries. In terms of the catalytic activity and structural stability, pyrochlore oxides (A2[B2-xAx]O7-y) have emerged as promising candidates. However, a limited use of A-site cations (e.g., lead or bismuth cations) of reported pyrochlore catalysts have hampered broad understanding of their catalytic effect and structure. More seriously, the catalytic origin of the pyrochlore structure was not clearly revealed yet. Here, we report the new nanocrystalline yttrium ruthenate (Y2[Ru2-xYx]O7-y) with pyrochlore structure. The prepared pyrochlore oxide demonstrates comparable catalytic activities in both ORR and OER, compared to that of previously reported metal oxide-based catalysts such as perovskite oxides. Notably, we first find that the catalytic activity of the Y2[Ru2-xYx]O7-y is associated with the oxidations and corresponding changes of geometric local structures of yttrium and ruthenium ions during electrocatalysis, which were investigated by in situ X-ray absorption spectroscopy (XAS) in real-time. Zn-air batteries using the prepared pyrochlore oxide achieve highly enhanced charge and discharge performance with a stable potential retention for 200 cycles

Thermally driven phase transition of cobalt hydroxide sheets via cobalt oxides to cobalt nanoparticles

Transition metal oxides, which include many stoichiometric variations, are formed into various crystal structures by the atomic arrangement of cations and anions according to stoichiometric composition and are used for a wide range of applications based on this. Among them, cobalt oxide, which has wide crystal structures depending on the lattice points of the anion and the valence of the Co cation, from its hydroxide formula, is attracting a lot of attention due to its interesting catalytic properties due to its crystal structure. In this study, using the synthesized Co(OH)(2) nanosheets, the real-time behavior of the phase transition that occurs when continuous heat is applied to the sample has been systematically analyzed using an aberration-corrected scanning transmission electron microscope. The layered Co(OH)(2) phase passes through hexagonal CoO and cubic CoO phases to finally become Co nanoparticles, but when the temperature is dropped in the hexagonal phase, spinel Co3O4 is formed. These results suggest that various phases included in transition metal oxides can be selectively implemented according to temperature range control

Effect of Addition of Fermented Soy Sauce on Quality Characteristics of Pork Patties during Refrigerated Storage

This study aimed to determine whether fermented soy sauce has a mutually synergistic effect on the quality and storage properties of pork patties, and to investigate the effects on the availability and physicochemical properties of various taste ingredients of soy sauce, a traditional Korean food ingredient. The experimental groups were as follows: Control (−): No additives; Control (+): 0.1% ascorbic acid; T1: 1% fermented soy sauce; T2: 3% fermented soy sauce; T3: 5% fermented soy sauce. No significant difference was detected in moisture, protein, and fat among the various treatment groups; however, ash content and water holding capacity increased and texture properties improved with the concentration of fermented soy sauce. The addition of fermented soy sauce during refrigerated storage for 10 days showed a positive effect on the storage properties. The peroxide value, content of thiobarbituric acid reactive substances and total phenolics, and 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity differed significantly in pork patties with different treatments and storage intervals. The effect of fermented soy sauce on the overall quality and storage properties of pork patties during refrigerated storage is relatively unknown. These findings demonstrate that the addition of fermented soy sauce improves the quality properties and antioxidant activity of pork patties