Thinking About the Nerve Impulse: The Prospects for the Development of a Comprehensive Account of Nerve Impulse Propagation (original) (raw)
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An Enquiry into the Foundations of the Understanding of the Nerve Impulse
Sir Andrew Fielding Huxley (1917-2012), the 1963 Nobel prize winning physiologist and biophysicist, was the the Jodrell Professor of Physiology (1960-69), and Royal Society Research Professor in Physiology (1969-83) at UCL. He and his colleague Sir Alan Lloyd Hodgkin distinguished themselves as scientists by developing a mathematical model that describes the ionic mechanism which is fundamental to how action potentials are initiated and propagated in nerve fibers. This essay will examine the inherent assumptions made in the Hodgkin-Huxley model, attempt to trace their historical origin, and address the question; where did the metaphorical equipment with which we understand the nerve impulse come from?
Progress in Neurobiology, 2018
Nerve impulse generation and propagation are often thought of as solely electrical events. The prevalence of this view is the result of long and intense study of nerve impulses in electrophysiology culminating in the introduction of the Hodgkin-Huxley model of the action potential in the 1950s. To this day, this model forms the physiological foundation for a broad area of neuroscientific research. However, the Hodgkin-Huxley model cannot account for non-electrical phenomena that accompany nerve impulse propagation, for which there is nevertheless ample evidence. This raises the question whether the Hodgkin-Huxley model is a complete model of the nerve impulse. Several alternative models have been proposed that do take into account non-electrical aspects of the nerve impulse and emphasize their importance in gaining a more complete understanding of the nature of the nerve impulse. In our opinion, these models deserve more attention in neuroscientific research, since, together with the Hodgkin-Huxley model, they will help in addressing and solving a number of questions in basic and applied neuroscience which thus far have remained outside our grasp. Here we provide a historico-scientific overview of the developments that have led to the current conception of the action potential as an electrical phenomenon, discuss some major objections against this conception, and suggest a number of scientific factors which have likely contributed to the enduring success of the Hodgkin-Huxley model and should be taken into consideration whilst contemplating the formulation of a more extensive and complete conception of the nerve impulse.
Innovative definition of nature of the nerve impulses
Ain Shams Engineering Journaljournal homepage: www.sciencedirect.com, 2019
Neuroscientists describe the nerve impulses as electrical signals that travel down an axon or as a wave that has an action or electric potential. Such description may recognize a nature of the nerve impulses as electric current. However; the traditional definition of electric current as flow of electrons stands against such direct recognition of the nerve impulses, so it is defined as ions or ionic current. It will be reviewed in this study an entropy approach and results of one of Faraday’s experiment which defined the electric current as electromagnetic waves that have an electric potential. Such definition of electric current is found to be consistent with recognized features of the nerve impulses. Accordingly, it is investigated in this article a definition of the nerve impulses as electric charges and not as ions to account for detected thermoelectric aspects of these electric impulses. Then, it is suggested thermoelectric mechanisms of their generation and propagation as electric charges in the neural system. Such conclusion will simplify replacement of damaged neural cells by artificial mechanisms
Proper Understanding of the Nerve Impulses and the Action Potential
World Journal of Neuroscience, 2023
Neurologists define the transmission of nerve impulses across the membranes of the neural cells as a result of difference in the concentration of ions while they measured an electric potential, called as an action potential, which allows the propagation of such nerve impulses as electrical signals. Such measurements should guide them to a logical explanation of the nerve impulses as electric charges driven by the measured action potential. However, such logical conclusion, or explanation, is ignored due to a wrong definition of the flow of electric charges as a flow of electrons that cannot pass through neural networks. According to recent studies, electric charges are properly defined as electromagnetic (EM) waves whose energy is expressed as the product of its propagating electric potential times their entropy flow which is adhered to the flow of such energy. Such definition matches the logical conclusion of the nerve impulses as electric charges, as previously explained, and defines the entropy of the neural network, measured by Ammeters, in Watt or Joule/Volt. The measured entropy represents a neurodiagnostic property of the neural networks that measures its capacity to allow the flow of energy per unit action potential. Theoretical verification of the innovative definition of nerve impulses is presented by following an advanced entropy approach. A proper review of the machine records of the stimulating electric charges, used in the diagnosis of the neural networks, and the stimulated nerve impulses or stimulated responses, represents practical verifications of the innovative definitions of the electric charges and the nerve impulses. Comparing the functioning of the thermoelectric generators and the brain neurons, such neurons are defined as thermoelectric generators of the electric nerve impulses and their propagating, or action, potential.
Reviews in the Neurosciences
The thermodynamic theory of action potential propagation challenges the conventional understanding of the nerve signal as an exclusively electrical phenomenon. Often misunderstood as to its basic tenets and predictions, the thermodynamic theory is virtually ignored in mainstream neuroscience. Addressing a broad audience of neuroscientists, we here attempt to stimulate interest in the theory. We do this by providing a concise overview of its background, discussion of its intimate connection to Albert Einstein’s treatment of the thermodynamics of interfaces and outlining its potential contribution to the building of a physical brain theory firmly grounded in first principles and the biophysical reality of individual nerve cells. As such, the paper does not attempt to advocate the superiority of the thermodynamic theory over any other approach to model the nerve impulse, but is meant as an open invitation to the neuroscience community to experimentally test the assumptions and predicti...
The electrodynamics of the nerve impulse
Mathematical Biosciences, 1988
The electrodynamics of the nerve impulse is described in the quasistatic limit in terms of physically well-differentiated components: the double layer of charge responsible for the action potential, and the ionic current which is invariant under Galilean transformation. The present framework, in which the role of the double layer is prominent, predicts quantitative changes in the ionic current and the rate of rise of the action potential that are produced by anesthetics which change the capacitance of the membrane. The nonspecific effects produced by changes in the capacitance of the membrane are discriminated from the specific effects which affect only the number of channels. We also calculate in the quasistatic limit the potential in all space for a given double layer of charges, obtaining expressions for the intracellular and extracellular potentials in terms of the action potential.
The Hodgkin-Huxley Nerve Axon Model
This technical note shows the use of the MLAB mathematical and statistical modelling system for solving the Hodgkin-Huxley differential equations for arbitrary initial conditions. The prevailing model of a nerve axon membrane is a pair of theories concerning the nature of the axon membrane with respect to active ("pumping") and passive (diffusion) steady-state transport of various ions across the membrane and with respect to time-dependent "gate" opening and closing which controls the active passage of ions through such "open gates". It is postulated that the membrane in a given state has a certain permeability for each given ion, and that this permeability is determined by the electrochemical potential across the membrane. The permeability, P C , of a membrane for a particular chemical species, C, is a measure of the ease of diffusion of C across the membrane in the presence of a concentration difference on either side of the membrane. In particular, u...
Neuroelectric potentials derived from an extended version of the Hodgkin-Huxley model
Journal of Theoretical Biology, 1966
In 1952, Hodgkin and Huxley and others generated a revolution in our concept of the axon membrane and how it propagates the action potential. In 1959, Bullock described another revolution, a "quiet revolution" in our concept of the functions performed by the remainder of the nerve cell. In this paper we have attempted to show a possible connection between these two revolutions. We have proposed that a single unifying concept, that of the Modem Ionic Hypothesis, can account for almost all of the diverse behavior described by Bullock. In addition, we have attempted to demonstrate the value of electronic analogs in the study of systems as complex as that of the neural membrane.