Thinking about the nerve impulse: A critical analysis of the electricity-centered conception of nerve excitability (original) (raw)
Related papers
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?
Frontiers in Cellular Neuroscience, 2019
Currently, a scientific debate is ongoing about modeling nerve impulse propagation. One of the models discussed is the celebrated Hodgkin-Huxley model of the action potential, which is central to the electricity-centered conception of the nerve impulse that dominates contemporary neuroscience. However, this model cannot represent the nerve impulse completely, since it does not take into account non-electrical manifestations of the nerve impulse for which there is ample experimental evidence. As a result, alternative models of nerve impulse propagation have been proposed in contemporary (neuro)scientific literature. One of these models is the Heimburg-Jackson model, according to which the nerve impulse is an electromechanical density pulse in the neural membrane. This model is usually contrasted with the Hodgkin-Huxley model and is supposed to potentially be able to replace the latter. However, instead of contrasting these models of nerve impulse propagation, another approach integrates these models in a general unifying model. This general unifying model, the Engelbrecht model, is developed to unify all relevant manifestations of the nerve impulse and their interaction(s). Here, we want to contribute to the debate about modeling nerve impulse propagation by conceptually analyzing the Engelbrecht model. Combining the results of this conceptual analysis with insights from philosophy of science, we make recommendations for the study of nerve impulse propagation. The first conclusion of this analysis is that attempts to develop models that represent the nerve impulse accurately and completely appear unfeasible. Instead, models are and should be used as tools to study nerve impulse propagation for varying purposes, representing the nerve impulse accurately and completely enough to achieve the specified goals. The second conclusion is that integrating distinct models into a general unifying model that provides a consistent picture of nerve impulse propagation is impossible due to the distinct purposes for which they are developed and the conflicting assumptions these purposes often require. Instead of explaining
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.
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.
The Hodgkin and Huxley model of the action potential
This review will survey the historical development of cellular neurophysiology, centring onthe revelatory discoveries and formalism of the Hodgkin and Huxley model. In the first section, I will discuss the state of the field before Hodgkin and Huxley’spioneering research – in an attempt to elucidate the framing problems that led Hodgkin and Huxley into conducting their research. In the second section, I will discuss the influence of the voltage clamp, and how it was applied by Hodgkin and Huxley to the study of the action potential of the squid giant axon. The third section will focus on the key experimental observations of the squid giant axon experiments. In the fourth section I will discuss their assumptions, and then proceed to present an essentialised form of the mathematical model. Throughout, I will comment on modern confirmations of their predictions
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...
Revisiting the Hodgkin-Huxley and Fitzhugh-Nagumo models of action potential propagation
Letters in Applied NanoBioScience
The influence of neuron mechanical deformation on the generation and propagation of the action potential is studied by revisiting the Hodgkin-Huxley (H-H) and the Fitzhugh-Nagumo (F-N) models within a coupled electromechanical framework. More specifically, effects of flexoelectricity and cellular membrane deformation on the kinetics of potassium channels are studied. Their activation and inactivation rate, as well as the appearance of time delay, are considered to describe changes in the propagation velocity of the action potential due to the axon deformation. The results obtained are supported by experimental evidence, although such phenomena are extremely challenging to analyze with existing tools. The electromechanical consideration of the generation and propagation of the action potential is a very promising field with important clinical implications and wide perspectives for further understanding the pathophysiology of various neurological disorders.