Neuron Function Inferred From Behavioral And Electrophysiological Extimates Of Refractory Period PdfBy Langley B. In and pdf 23.05.2021 at 05:55 9 min read
File Name: neuron function inferred from behavioral and electrophysiological extimates of refractory period .zip
- Absolute refractory period of neurons involved in MFB self-stimulation.
- Revealing neuronal function through microelectrode array recordings
- Artificial Shape Perception Retina Network Based on Tunable Memristive Neurons.
Relay cells are prevalent throughout sensory systems and receive two types of inputs: driving and modulating.
Absolute refractory period of neurons involved in MFB self-stimulation.
These metrics are regularly updated to reflect usage leading up to the last few days. Citations are the number of other articles citing this article, calculated by Crossref and updated daily.
Find more information about Crossref citation counts. The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. The tremendous therapeutic potential of voltage-gated sodium channels Na v s has been the subject of many studies in the past and is of intense interest today.
Here we summarize the current status of research in the Na v field and present the most relevant recent developments with respect to the molecular structure, general physiology, and pharmacology of distinct Na v channel subtypes. We discuss Na v channel ligands such as small molecules, toxins isolated from animal venoms, and the recently identified Na v 1. Finally, we examine possible therapeutic applications of Na v ligands and provide an update on current clinical studies.
Figure 1. Na v channel architecture. Each domain contains six transmembrane helical segments S1—6. Plus signs in S4 represent the positively charged voltage sensor containing a number of arginine or lysine residues. Movement of S6 segments lead to channel opening in response to membrane depolarization.
Segments S5, S6, and the connecting pore-loops P-loops form the channel pore. B Extracellular view of the open-channel conformation crystal structure of Na v Ms, a marine bacteria from Magnetococcus sp. C Side view of the open-channel conformation crystal structure of bacterial Na v Ms. Figure 2.
Tissue expression of Na v subtypes and effects of Na v dysfunction on physiology. Figure 3. Toxins isolated from animal venoms that act on Na v channels. A Tetrodotoxin TTX, 1 extracted from the puffer fish. Figure 4. B,C An extracellular and side view, respectively, of the crystal structure of bacterial Na v Ms. Figure 5.
A Amino acid residues known to bind nonselective local anesthetics are conserved among Na v subtypes and are highlighted in blue. Figure 8. Na v s are very complex molecular structures that rapidly transition through different states closed, open, or inactivated. Ligand binding and functional activity often depends on the conformational state of the channel state dependence , which makes the assessment of structure—activity relationships challenging. The high degree of amino acid sequence homology among the different Na v subtypes makes identifying or designing subtype-selective ligands extremely difficult.
Some Na v ligands show potency differences across animal species, which can complicate the assessment of efficacy in preclinical in vivo models and the design of safety studies. Manuel de Lera Ruiz received his B.
After completion of his Ph. Richard L. Kraus received his Ph. We thank Dr. Christopher Burgey, Dr. Joseph Duffy, Dr. Andrea Houghton, Dr. Mark Layton, and Dr. Cameron Cowden for their constructive comments and suggestions. Editing support from Philippa Solomon is greatly acknowledged. We also thank Dr. Jaume Balsells-Padros for all his encouraging support to put this manuscript together. View Author Information. Cite this: J. ACS AuthorChoice.
Article Views Altmetric -. Citations Abstract High Resolution Image. Voltage-gated ion channels VGICs are transmembrane proteins that play important roles in the electrical signaling of cells. The activity of VGICs is regulated by the membrane potential of a cell, and open channels allow the movement of ions along an electrochemical gradient across cellular membranes. Depending on the ions conducted, VGICs can be classified as voltage-gated sodium, 1 potassium, calcium, or chloride channels.
Voltage-gated sodium currents were discovered by Hodgkin and Huxley in when studying the electric conductance in axons of giant squids. A novel family of Na v 2 channels was discovered recently, however, little is known about its function. In contrast, prokaryotic Na v channels that have been used to explore the structure of eukaryotic Na v s are formed by homotetramers.
In primary sensory neurons, for example, the depolarization of an axon by a noxious stimulus leads to the transmission of sensory information through the nervous system to the brain which may be perceived as pain. In skeletal and cardiac muscle cells, received action potentials produce muscle contraction enabling body movements and blood flow. Interestingly, Na v channels are the molecular targets for a broad range of natural neurotoxins such as tetrodotoxin TTX, 1 , Figures 3 A and 6 , saxitoxin STX, 2 , Figure 6 , and batrachotoxin BTX, 11 , Figures 3 B and 8 as well as peptide toxins isolated from the venoms of scorpions, spiders, sea anemones, and cone snails such as those in Figures 3 C—F.
Those toxins interact with at least six known receptor sites, named Site 1—6, and inhibit or modulate the gating properties of Na v channels. All Na v subtypes known to date can be classified by their sensitivity to the guanidine-based neurotoxin TTX, a toxin isolated from the puffer fish. Na v channels are very dynamic structures. There are three primary states for Na v channels: a closed resting state, an open conducting state, and a nonconducting inactivated state.
Many known natural and synthetic Na v ligands display different affinities to distinct ion channel states, a phenomenon called state dependence. In contrast, other ion channel modulators show little preference for a particular channel state in their interactions and are considered state-independent modulators. The role of Na v channels in neuronal and cardiac disorders has long been known, and nonselective sodium channel blockers have been developed as anticonvulsant, antiarrhythmic, and local anesthetic drugs in the past.
More recently, mutations in human genes encoding Na v channel subtypes have been linked to channelopathies such as epilepsy, cardiac arrhythmias, and chronic pain syndromes. The analysis of numerous gain and loss of function mutations have revealed invaluable information about the physiological role of Na v channels in disease. Currently, enormous efforts are underway to find and study the effects of subtype-selective Na v ligands in preclinical disease models and eventually in the clinic.
The wealth of publications and patents in recent years reflects the high interest in this research field. In , approximately articles on Na v s were published, followed by a further in Among these, approximately articles on the Na v 1. In addition, we will discuss the current status of the most significant natural, semisynthetic, and artificial ligands of Na v channels and provide an update on recent clinical developments.
Molecular Architecture. Just over 30 years ago, Catterall, Beneski, and Hartshorne proposed the basic structure of Na v channels based on covalently labeling protein components of purified rat brain Na v s with a photoactive derivative of a scorpion toxin. Of paramount importance is the complete sequencing of the human genome, which has provided us with the identification of ion channel proteins.
Numerous studies using prokaryotic Na v channels have provided us with insight into the structure and function of bacterial Na v channels, translatable to eukaryotic Na v channels.
In contrast, prokaryotic Na v channels are far simpler, consisting of homotetramers of four identical polypeptide chains. Each polypeptide chain contains six transmembrane segments S1—S6 and exhibits high sequence homology when compared to eukaryotic domains. High Resolution Image.
The flexibility of the VSD is primarily mediated by movement of positively charged arginine and lysine residues positioned at every third residue within each S4 helix. The four voltage-sensing domains are arranged around a central aqueous channel formed by the pore domain PD.
Upon depolarization, the positively charged S4 transmembrane segments are believed to move toward the extracellular surface. This motion is transferred to the pore domain via intracellular linkers, causing a conformational change that results in the opening of the channel pore.
During depolarization, the channel inactivates as the inactivation gate vide infra folds into the channel pore. Upon membrane repolarization, Na v channels recover from inactivation and the S4 segments return to their resting positions, becoming available for the next depolarization.
From a study of the functional contributions of the amino acid residues at the VSD of skeletal muscle channel subtype Na v 1. This study showed that, surprisingly, not all of the four S1—S4 structures contributing to the VSD adopt the same structural conformation at a specific Na v channel state. Segments S5, S6, and the extracellular connecting pore-loops P-loops form the channel pore and the selectivity filter SF.
As will be discussed later in this review, most Na v -blocking drugs bind to residues at the central water-filled cavity of the pore. Recent structural Na v studies have revealed the existence of additional lateral lipid-filled openings, called fenestrations, connecting the exterior of the channel protein with the central pore. Na v channel fenestrations could create pathways for small hydrophobic Na v blockers to access the pore from the side through the membrane. Kaczmarski and Corry have investigated Na v subtype specific factors contributing to the size and dynamics of Na v channel fenestrations using MDS and several bacterial and eukaryotic Na v models.
Surprisingly, the structure also has an outer ion site in the selectivity filter vide infra that suggests the presence of multiple ion-binding sites and the possibility that various ions may occupy the selectivity filter simultaneously. The PD includes the selectivity filter SF, Figure 1 C , the narrowest part of the pore that distinguish ions with similar charges and radii. This is due to the fact that the conformations of the functional groups of the amino acids that constitute the SF are not identical, adopting an asymmetric tetramer.
This observation suggests that a similar asymmetric phenomena may occur in eukaryotic counterparts where the level of asymmetry between the four domains is higher.
Revealing neuronal function through microelectrode array recordings
These metrics are regularly updated to reflect usage leading up to the last few days. Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts. The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. The tremendous therapeutic potential of voltage-gated sodium channels Na v s has been the subject of many studies in the past and is of intense interest today.
Quantitative Biology: Dynamics of living systems View all 13 Articles. Microelectrode arrays and microprobes have been widely utilized to measure neuronal activity, both in vitro and in vivo. The key advantage is the capability to record and stimulate neurons at multiple sites simultaneously. However, unlike the single-cell or single-channel resolution of intracellular recording, microelectrodes detect signals from all possible sources around every sensor. Here, we review the current understanding of microelectrode signals and the techniques for analyzing them. We introduce the ongoing advancements in microelectrode technology, with focus on achieving higher resolution and quality of recordings by means of monolithic integration with on-chip circuitry. We show how recent advanced microelectrode array measurement methods facilitate the understanding of single neurons as well as network function.
Neuron Function Inferred from Behavioral and Electrophysiological Estimates of Refractory Period Article · Info & Metrics · eLetters · PDF. Loading.
Artificial Shape Perception Retina Network Based on Tunable Memristive Neurons.
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Abstract The refractory period of the directly stimulated neurons whose excitation elicits behavior can be measured by variation of the intra-pair interval of trains of stimulating pulse pairs. It is shown that at high frequencies of stimulation e.