- Email: [email protected]
Innovative definition of nature of the nerve impulses
Ain Shams Engineering Journal xxx (xxxx) xxx
Contents lists available at ScienceDirect
Ain Shams Engineering Journal journal homepage: www.sciencedirect.com
Engineering Physics and Mathematics
Innovative definition of nature of the nerve impulses Salama Abdelhady Faculty of Energy Engineering, Aswan University, Egypt
a r t i c l e
i n f o
Article history: Received 10 July 2019 Revised 11 October 2019 Accepted 28 October 2019 Available online xxxx Keywords: Nerve impulses Entropy Electric current Ionic current Maxwell’s equation
a b s t r a c t 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. Ó 2019 THE AUTHOR. Published by Elsevier BV on behalf of Faculty of Engineering, Ain Shams University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-ncnd/4.0/).
1. Introduction Neuroscientists use interchangeably two terms to describe the nerve impulse: ‘‘electric signals” and ‘‘action potential” [1,2]. Physically, these two terms cannot express the same thing as the electric signal represents flow of energy and the action potential is a measure of a property that drives such energy through the axon while it cannot flow as a wave by itself [3]. It was possible by the known batch-clamp techniques to measure the currentvoltage characteristics of the cell’s membrane that indicate the possibility of flow of the nerve impulses as electric charges through the neural system and not necessary as ionic current [4]. Similarly, the description of the nerve impulses as ionic current, according to neuroscientists, contradicts the observed nature of the nerve impulses as waves since the ionic current hasn’t a wavy nature [5]. However; the traditional definition of electric current as flow of electrons represents the main obstacle that forced the neuroscientists to abandon a description of these electric signals directly as electric current or the nerve impulses as electric charges. Accord-
ingly; it will be introduced in this study the experimental and mathematical proofs of an innovative definition of electric current as flow of electromagnetic waves driven by an electric potential [6]. This innovative definition of electric current is found to be consistent with the observed characteristics of the flow of nerve impulses as electric signals or as a wave of electric actionpotential. Such consistency will be the evidence of a new definition of a nature of the nerve impulse directly as an electric charge that is forced to flow by the action potential. Truth of this postulated definition of the nerve impulse deletes known misconception in neurosciences and finds plausible explanation of the thermoelectric aspects of the nerve impulses which cannot be explained by the traditional definition of nerve impulses as ionic current [7]. It will be discussed also how the detected temperature difference of the neuronal cells may indicate a mechanism of conversion of the heat produced by biochemical reactions in the neural cells into electric energy by a thermoelectric effect [8]. Dealing with the nerve impulses as electric current of thermal aspects can allow the use of nanoparticles in the neural systems to motivate the stimulation the neural cells by increasing their heat transfer and entropy production processes [9,10].
Peer review under responsibility of Ain Shams University.
2. A nature of the electric charges
Production and hosting by Elsevier E-mail address: [email protected]
In one of his experiments, Faraday succeeded in electrifying a ray of light by subjecting such a ray of light to an electric field [11,12]. According to results of his experiments, he found that
https://doi.org/10.1016/j.asej.2019.10.014 2090-4479/Ó 2019 THE AUTHOR. Published by Elsevier BV on behalf of Faculty of Engineering, Ain Shams University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Please cite this article as: S. Abdelhady, Innovative definition of nature of the nerve impulses, Ain Shams Engineering Journal, https://doi.org/10.1016/j. asej.2019.10.014
2
S. Abdelhady / Ain Shams Engineering Journal xxx (xxxx) xxx
the magnetic field can indirectly influence the behavior of such electrified light wave that means it is converted into electric current [13]. The influence or effect that Faraday observed is now known as Faraday’s rotation because his experiment illustrated the rotation of an electrified ray of light by the action of magnetic field, whatever the magnet’s configurations are, as seen in Fig. 1 [14]. According to the found results of Faraday’s experiment; the electric current may be interpreted as electrified electromagnetic wave or as an electromagnetic wave which has an electric potential [15]. Such interpretation is visualized in Fig. 2 by casting the Maxwell’s wave equations into an energy frame of reference where the time coordinate ‘‘t” in the wave equations is replaced by entropy ‘‘s” which is mainly a function of time and energy [15,16]. So, we get the following form of the modified Maxwell’s equations defined by three coordinates: the electric field E, the magnetic field H, and the entropy S as follows [17]:
! 1 @2 r 2 2 E¼0 c s 2
ð1Þ
! 1 @2 r 2 2H¼0 c s 2
ð2Þ
Fig. 2 shows also a graphical representation of the flowing electric and magnetic energies in an electromagnetic wave which can be estimated by the absolute value of the sum of the areas swept by the electric wave and the magnetic wave as follows [18]:
Z 2p
Fig. 2. Representation of flow of Electromagnetic waves in Energy frame of references composed of the energy coordinates: E-H-s coordinates, where the flow of the electric wave is shown in an E-s plane and the flow of the magnetic wave is shown in an H-s plane [18].
vector of the space coordinate and the angular velocity of the moving wave and u is the phase shift of the wave. The stated solution of Maxwell’s equations defined by the Eqs. (4) and (5) is represented graphically in Figs. 3A and 3B [18]. Fig. 3A represents a flow of negative charges where the electric wave is oscillating around a nega
ð3Þ
tive potential (D E). Similarly; Fig. 3B shows the flow of positive electric charges in the form of electromagnetic waves of positive
Eq. (3) determines the energy flow per wave, or the energy of the
electric potential (+D E) in a frame of energy coordinates E, H, and S. Both figures show visualization of ionized photons or electric
h¼
ðjEdSe j þ HdSmag: ÞJoule=wave
0
photon, denoted as ‘‘h.” The first integral in the R.H.S. in this equation represents the imparted electric energy of zero electric potential and the second term represents the imparted magnetic energy of zero magnetic potential per wave [18]. The sum of both energies is the quantized energy per wave ‘‘h } Joule/wave which is known as the energy of a photon [18]. According to such representation of the energy flow in an electromagnetic wave; it was possible to visualize the electrifying of the light in Faraday’s experiment as if the light gains a negative or a positive potential during its passing through an electric field. In other words; the electric current is considered as a special electromagnetic wave whose electric energy gained a negative or a positive potential during its electrifying process [18]. Such wave is described mathematically as a special solution of the modified Maxwell’s equations which have a permanent electric potential,
charges as electromagnetic of energy “ h” Joule=wave whose elec
tric potential is negative or positive of the value ‘‘þ= D E.” This means that the electric potential of the flowing current or charge is variable [19]. Considering the electric current as electromagnetic waves
whose energy has electric potential ‘‘þ= D E” paved the way to an innovative definition of electric current that deletes confusions in electromagnetism caused by the traditional definition of electric current as flow of electrons as shown in pevious articles [19]. However, the fact that light and electromagnetism waves or electric current are related had paved in the past a way for Maxwell’s
positive or negative, of the magnitude ‘‘þ= D E } as follows [19]:
Eðr; sÞ ¼ E cos ðkr þ xs þ uÞ þ = D E
ð4Þ
Hðr; sÞ ¼ Hcosðkr þ xs þ uÞ
ð5Þ
In these equations; r and s are the space and entropy coordinates; E and H are the electric and magnetic potentials, k and x are the unit
Fig. 1. Rotation of an electrified ray by a magnetic field (18).
Fig. 3A. Flow of negative electric charges as flow of electromagnetic waves of –ve potential where the electric energy in the E-s plane is oscillating around the negative potential ‘‘D E” [18].
Please cite this article as: S. Abdelhady, Innovative definition of nature of the nerve impulses, Ain Shams Engineering Journal, https://doi.org/10.1016/j. asej.2019.10.014
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S. Abdelhady / Ain Shams Engineering Journal xxx (xxxx) xxx
Fig. 3B. Flow of negative electric charges as flow of electromagnetic waves of –ve potential where the electric energy in the E-s plane is oscillating around the negative potential ‘‘+D E” [18].
entropy (s) brilliant theoretical demonstration of the definition of thermal radiation as electromagnetic waves, and their identity with light [20]. Additionally; the Tesla’s discovery of ‘‘Radiant energy” can be also interpreted as normal radiation of electric energy or as electromagnetic waves of electric potential from the Tesla’s tower [21]. Tesla’s experiment is found similar to the discharge of accumulation of electric charges as electrified electromagnetic waves from clouds during the lightening [22]. These results and foundations prove the truth of interpreting the electric current as electromagnetic waves of electric potential [23]. Such innovative definition of electric current succeeds also in deleting the ‘‘duality confusion” and represents a clear definition of the nature of electric charge as a special electromagnetic wave [24]. Researchers applied such clear definition of the electric charge in many applications as it wasn’t clearly defined in literature [25]. 3. A nature of the nerve impulses Recent observations of the neuroscientists defined the nerve impulses in general as electrical signals that travel down an axon or as an electric wave forced by an ‘action potential’ [26]. Such definition of the nerve impulse is directly consistent with the previously introduced definition of electric current as flow of electromagnetic waves of electric potential [23]. Neuroscientists rejected such definition of the nerve impulses as electric current since the electric current had been defined as flow of electrons and they have common understanding of the impossibility of flow of electrons through organic fibers [27]. However; the flow of the electric current through a patch from the cell membrane was recently measured and we get the description of fully activated current-voltage characteristics of such patch [28]. These measurements prove the possibility of flow of electric current or charges through the neural system or the ability of the cell membrane to conduct the nerve impulses as electric current [29]. Similarly; there are research teams and technologists who succeeded in pumping electric energy through optical fiber system [30–32]. Such results confirm the possibility of flow of the nerve impulses, as electric current, through the axon [33] Fig. 4 shows the nerve impulse as an energy wave that has an electric potential, or action potential, that decays with time [34]. However, the horizontal axis in Fig. 4, which indicates originally the time, is replaced in the figure by entropy which is mainly a function of time [35]. Such modification shows the shaded area in Fig. 4 as electric energy that flows during a nerve impulse and estimated by the following integral:
Z
Eimpulse ¼
EdS
ð6Þ
Fig. 4. Decay of the action potential as function of entropy increase during the nerve impulse.
Eq. (6) evaluates the flow of electric energy per nerve impulse as defined by the hatched areas in Fig. 4. However; such energy can be evaluated also by the same integral of the electric darkened
energy, limited by the potential difference ‘‘D E,” in Fig. 3A or Fig. 3B. So, the definition of the nature of the flow of nerve impulse as electric current fits its observed description as electric signals which have electric potential, according to Fig. 4. However, its traditional definitions as ionic current or as action potential are confusing as the dimensions of these two terms are not consistent and both definitions haven’t the recorded wavy nature of the measured nerve impulses [36]. Additionally, the description of the nerve impulses as electric charge affords plausible explanations for measured thermoelectric features that accompany the generation and propagation of the nerve impulses through the neural system while its definition as ionic current limited our investigations to its electrochemical aspects only while it has defintely thermolelectric aspects [37]. 4. Thermoelectrical aspects of the electric current Thermoelectricity is concerned by coupled conversion of heat and electricity. Such phenomena are mainly characterized by the Seebeck effect which is defined as follows [38]:
S¼
DV DT
ð5Þ
According to the new definition of electric current, this coefficient relates the conversion of the thermal potential of the incident heat ‘‘DT,” into electric potential ‘‘DV” by the Seebeck effect. Thus it characterizes the conversion of the thermal radiation, as electromagnetic waves of thermal potential DT, into electric current as electromagnetic waves of electric potential ‘‘DV”[39]. Such definition of Seebeck effect is applied in many thermoelectric devices as thermocouples or thermopiles, thermoelectric generators, and photovoltaic cells [40]. In case of photovoltaic cells, the thermal potential of the incident radiation is converted into electric potential, by the Seebeck effect, when it crosses the p-n junction of the PV cell. Such electric potential is proportional to the thermal potential of the incident radiation by Seebeck coefficient, as constant of proportionality, according to Eq. (5) [41]. Scientists succeeded in manufacturing organic photovoltaic cells that means the possibility of the functioning of neural cells as photovoltaic cells as will be discussed later.
Please cite this article as: S. Abdelhady, Innovative definition of nature of the nerve impulses, Ain Shams Engineering Journal, https://doi.org/10.1016/j. asej.2019.10.014
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S. Abdelhady / Ain Shams Engineering Journal xxx (xxxx) xxx
Fig. 6. Distribution of ions across the cell membrane.
Fig. 5. Movement of charge carriers in the photovoltaic cell [40].
The original discovery of the Seebeck effect and thermoelectricity was related to the neural system of a frog where the generated electric potential by dissimilar metals caused the frog’s muscles to contract [42]. Such thermoelectric phenomena are used also in design of thermoelectric generators which consist of a higher plate at high temperature ‘‘Th ” and a lower plate of low temperature ‘‘Tl ” as shown in Fig. 5. [43]. Both plates are connected by legs of two dissimilar materials which have different Seebeck coefficients:Heat flows across these legs by the temperatures difference‘‘ðTh Tl Þ” between the two surfaces of the module. The heat flow is converted into electric current due to conversion of its thermal potential into electric potential when crossing junctions by the Seebeck effect [43]. Scientists succeeded in production of organic thermoelectric generators that convert the flowing heat through the thermoelectric generator into electric current by the Seebeck effect [44]. 5. Thermoelectric aspects of the electric nerve impulses Soliton model and other neural models were used to study the found thermoelectric aspects of the nerve impulses during its generation and flow through the neural system [45,46]. However; these models were adhered to the definition of the nerve impulses as ionic current which restricted these studies to its electrochemical aspects only [47]. Recognizing the nature of nerve impulses as electric charges, it is possible to start a new approach in the field of nerve impulses to investigate some measured thermoelectrical effects of these impulses. As an example; it is possible to discuss the detected temperature difference of the neuronal cells and the higher temperature of the brain than the body where it consumes 20% of the body’s oxygen and energy [9,47,48]. So, we may think the generation of the nerve impulses as electric charge in the cell’s membrane by Seebeck effect that may convert the generated heat energy during the biochemical exothermic reactions in the stimulated cells into electric energy [49]. The similarity of distribution of the ions in the PV cell, as seen in Fig. 5, and in the neural sell, as found in Fig. 6, may indicate a new approach for investigating the generation of the nerve impulses as electric charge in the neural cells by similar mechanism of the PV cells [50]. Similarly; it is possible to investigate the transmission of the nerve impulses as flow of electric current directly by conduction across the cell membrane and along the axon [51]. Of course; the truth of such approach is in need to hard work and sophisticated studies to solve many ambiguities in the field of neurosciences.
According to the previously explained characteristics of thermoelectric generators, crossing the junctions of the legs of the generator converts the thermal potential of the flowing heat into accumulating electric potential and covert the heat flow into electric current [52,53]. Similarly; it is possible to think the action of the successive Sodium and Potassium channels connecting the inner side and outer side of the neural cells as the actions of legs of the thermoelectric generators [54]. This proposal represents a new approach to the generation of electric current in the neural cell. Such proposals are sustained by the success of scientists and technologists in manufacturing organic PV cells and thermoelectric generators [44,55]. 6. Conclusions According to an innovative definition of the electric current as flow of electromagnetic waves of electric potential; it was possible to recognize the nature of the flow of nerve impulses directly as electric current whose potential was traditionally defined as the ‘‘Action Potential.” Such recognized nature verifies the recorded features of the nerve impulses as an electric wave of electric potential while its definitions as ionic current or an action potential contradict such features. The introduced definition allows also the study of detected thermoelectric aspects of the nerve impulses and suggests thermoelectric mechanisms for their generation by Seebeck effect. References [1] Brown AG. Nerve cells and nervous systems. An Introduction to Neuroscience. 2nd ed. Springer, 2001. [2] Squire L et al. Fundamentals of neurosciences. 3rd ed. 2013. [3] Jewett Jr, Serway RA. Physics for scientists and engineers with modern physics. 7th ed. Thomson; 2008. [4] Sakmann B, Neher E. Patch clamp techniques for studying ionic channels in excitable membranes. Annu Rev Physiol 1984;46:455. [5] Hamill OP et al. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Eur J Physiol 1981;391:85. [6] Abdelhady S, Cheng C. Advanced thermodynamics engineering. 1 st edi. Scitus Academics; 2019. [7] Benjamin D et al. Thinking about the nerve impulse: A critical analysis of the electricity centered conception of nerve excitability. Prog Neurobiol 2018;169:172. [8] Ryuichi T et al. Detection of temperature difference in neuronal cells. Nature, Scientific Reports 2016;6:1. [9] Sheikholeslami M, Jafaryar M, Shafee A, Zhixiong L, Li H. fRizwan-ul, Heat transfer of nanoparticles employing innovative tabulator considering entropy generation, Elsevier. Int J Heat Mass Transf 2019;136:1233–40. [10] Sheikholeslami M. New computational approach for exergy and entropy analysis of nanofluids under the impact of Lorentz force through a porous media. Elsevier Comput Method Appl Mech Eng 2019;344(1):319–33. [11] Faraday M. Experimental researches in electricity, nineteenth series. Phil Trans R Soc Lond 1846;136:1.
Please cite this article as: S. Abdelhady, Innovative definition of nature of the nerve impulses, Ain Shams Engineering Journal, https://doi.org/10.1016/j. asej.2019.10.014
S. Abdelhady / Ain Shams Engineering Journal xxx (xxxx) xxx [12] Fraday M. Experimental Researches in Chemistry and Physics. London: Richard Taylor and William Francis; 1895. [13] Williams LP, Faraday M. A biography. New York: Basic Books; 1965. [14] Jenkins A. Michael Faraday’s mental exercises: an artisan essay-circle in regency London. Oxford University Press; 2008. [15] Anderson DL. The Discovery of the Electron. Princeton, N.J.: Van Nostrand; 1964. [16] Gosline A. Thunderbolts from space. New Sci 2005;186:30. [17] Abdelhady S. An advanced review of thermodynamics of electromagnetism. Int J Res Stud Sci Eng Technol 3 (2015) 10. [18] Abdelhady S. A fundamental equation of thermodynamics that embraces electrical and magnetic potentials. J Electromagnet Anal Appl 2010;2:162. [19] Abdelhady S. Comments concerning measurements and equations in electromagnetism. J Electromagnet Anal Appl 2010;2:217. [20] Feynman RP, Leighton RB, Sands M. The Feynman lectures on physics. Addition Wesley; 1969. [21] Tesla N. The effect of static on wireless transmission. Electr Experimenter 2019;16:627. [22] Karthick S, Jason G, Lightning as atmospheric electricity conference paper in Canadian conference on electrical and computer engineering; 2006. [23] Abdelhady S et al. Thermodynamics: fundamentals and its application in science. Auris Reference. 1st ed; 2017. [24] Abdelhady S. Innovative understanding of the duality confusion, the photovoltaic and the magnetocaloric effects. Elsevier Publishing, Ain Shams Engineering Journal, Engineering Physics and Mathematics 2018;9:2283. [25] Maloney D et al. Surveying students’ conceptual knowledge of electricity and magnetism. Am J Phys Phys Educational Res Suppl 2001;69:S12. [26] Pang et al. The mechanism of generation of nerve impulse and its features of propagation along the nerve fiber cells in living systems 2018;5:4. [27] Weaver Q. Molecular biology. USA: MC. Graw Hill; 2000. [28] White PJ et al. Advanced patch-clamp techniques and single-channel analysis. J Exp Bot 1999;50:1037. [29] Armstrong CM, Gilly WF. Access resistance and space clamp problems associated with whole-cell patch clamping. Provides direct evidence for the role of Annexins in the Methods in Enzymology 1992;207:100. [30] Sato J, Furugori H, Matsuura M. 40-Watt power using double clad fiber for optically powered radio. Optical Fiber Communication Conference, Los Angeles; 2015. [31] Bulusu A, Walker D. Review of electronic transport models for thermoelectric materials. Superlattices Microstruct 2008;44:1–14. [32] Ari M. Taplamacioglu MC. Electrical power over fiber optics. Int J Tech Phys Probl Eng 2010;2:85–90. [33] Castelfranco AM, Hartline D. Review: Evolution of rapid nerve conduction, brain research. Elsevier Publishers 2016:641:11–33. [34] Bullock TH, Orkand R, Grinnell A. Introduction to nervous systems. San Francisco, CA: W. H. Freeman and Co.; 1977. p. 559. [35] Andrew S, Johnson W. The soliton and the action potential– primary elements underlying sentience. Front Physiol 2018;9:779. [36] Abdelhady S. An approach to a universal system of units. J Electromagn Anal Appl 2010;2:549–56. [37] Clay JR. Novel description of ionic currents recorded with the action potential clamp technique: application to excitatory currents in suprachiasmatic nucleus neurons. Neurophysio 2015;114:707. [38] Iordanishvili EK. Thermodynamic potential of thermoelectricity. J Thermoelectr 1981;41:1.
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[39] Van Herwaarden AW, Sarro PM. Thermal sensors based on the seebeck effect. Sens Actuat 1986;10:321. [40] Riffat SB, Ma X. Thermoelectrics: a review of present and potential applications. Appl Therm Eng 2003;23:913. [41] Wurfel U, Cuevas A. Charge carrier separation in solar cells. IEEE J Photovoltaics 2015;5:461. [42] Tasaki I, Byrne P. Heat production associated with a propagated impulse in bullfrog myelinated nerve fibers. Jpn J Physiol 1992;42:805. [43] Abdelhady S. Advanced physics of thermoelectric generators and photovoltaic cells. Am J Phys Appl 2018;6:133. [44] Bubinova O, Crispin X. Towards polymer-based organic thermoelectric generators. Energy Environ Sci 2012;5:9345. [45] Baccus S. Synaptic facilitation by reflected action potentials: Enhancement of transmission when nerve impulses reverse direction at axon branch points. Proc Natl Acad Sci Neurobiol 1998;95:8345. [46] Hormuzdi SG et al. Electrical synapses: a dynamic signaling system that shapes the activity of neuronal networks. Biochim Biophys Acta 2004;1662:113. [47] Raichle ME. Two views of brain function. Trends Cogn Sci 2010;14:180. [48] Clay J. Determining K+ channel activation curves from K+ channel currents often requires the Goldman-Hodgin-Katz equation. Front Cell Neurosci 2009;3:1. [49] Hille B, Catterall WA. Electrical Excitability and Ion Channels. Basic neurochemistry: molecular, cellular, and medical aspects. Philadelphia: Lippincott-Raven; 1999. [50] Mummert H, Gradmann D. Action potentials in Acetabularia: measurement and simulation of voltage-gated fluxes. J Membr Biol 1991;124:265. [51] Hovik C. Comparative physiology of conduction in nerve and muscle. AM. Zollogist 1962;2:5. [52] Herwaarden AW, Sarro V. Thermal sensors based on the seebeck effect. Sens Actuat 1986;10:321. [53] Weiling L, Shantung T. Recent developments of thermoelectric power generation. Chin Sci Bull 2004;49:1212.|. [54] Goldin AL. Neuronal Channels and Receptors, Molecular Neurology. Burlington, MA: Elsevier Academic Press; 1991. [55] Rweyagila ER. A review of organic photovoltaic energy source and its technological designs. Int J Photo-energy 2017.
Salama Abdelhady A full Professor of energy systems in Aswan University, has obtained his Ph. D degree from Bm University in 1975, He was the co-Founder & Dean of the Faculty of energy engineering in Aswan University, he has many researches in the field of thermodynamics, heat transfer, energy conservation and renewable energy, led many projects in the field of reverse engineering and CSP, he is a member in the supreme committee of power engineering for three periods, he was a visiting professor in Lehigh university, he was the head of departments of power engineering in MTC, High Institute of Energy, CIC, and Heliopolis University.
Please cite this article as: S. Abdelhady, Innovative definition of nature of the nerve impulses, Ain Shams Engineering Journal, https://doi.org/10.1016/j. asej.2019.10.014
Contents lists available at ScienceDirect
Ain Shams Engineering Journal journal homepage: www.sciencedirect.com
Engineering Physics and Mathematics
Innovative definition of nature of the nerve impulses Salama Abdelhady Faculty of Energy Engineering, Aswan University, Egypt
a r t i c l e
i n f o
Article history: Received 10 July 2019 Revised 11 October 2019 Accepted 28 October 2019 Available online xxxx Keywords: Nerve impulses Entropy Electric current Ionic current Maxwell’s equation
a b s t r a c t 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. Ó 2019 THE AUTHOR. Published by Elsevier BV on behalf of Faculty of Engineering, Ain Shams University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-ncnd/4.0/).
1. Introduction Neuroscientists use interchangeably two terms to describe the nerve impulse: ‘‘electric signals” and ‘‘action potential” [1,2]. Physically, these two terms cannot express the same thing as the electric signal represents flow of energy and the action potential is a measure of a property that drives such energy through the axon while it cannot flow as a wave by itself [3]. It was possible by the known batch-clamp techniques to measure the currentvoltage characteristics of the cell’s membrane that indicate the possibility of flow of the nerve impulses as electric charges through the neural system and not necessary as ionic current [4]. Similarly, the description of the nerve impulses as ionic current, according to neuroscientists, contradicts the observed nature of the nerve impulses as waves since the ionic current hasn’t a wavy nature [5]. However; the traditional definition of electric current as flow of electrons represents the main obstacle that forced the neuroscientists to abandon a description of these electric signals directly as electric current or the nerve impulses as electric charges. Accord-
ingly; it will be introduced in this study the experimental and mathematical proofs of an innovative definition of electric current as flow of electromagnetic waves driven by an electric potential [6]. This innovative definition of electric current is found to be consistent with the observed characteristics of the flow of nerve impulses as electric signals or as a wave of electric actionpotential. Such consistency will be the evidence of a new definition of a nature of the nerve impulse directly as an electric charge that is forced to flow by the action potential. Truth of this postulated definition of the nerve impulse deletes known misconception in neurosciences and finds plausible explanation of the thermoelectric aspects of the nerve impulses which cannot be explained by the traditional definition of nerve impulses as ionic current [7]. It will be discussed also how the detected temperature difference of the neuronal cells may indicate a mechanism of conversion of the heat produced by biochemical reactions in the neural cells into electric energy by a thermoelectric effect [8]. Dealing with the nerve impulses as electric current of thermal aspects can allow the use of nanoparticles in the neural systems to motivate the stimulation the neural cells by increasing their heat transfer and entropy production processes [9,10].
Peer review under responsibility of Ain Shams University.
2. A nature of the electric charges
Production and hosting by Elsevier E-mail address: [email protected]
In one of his experiments, Faraday succeeded in electrifying a ray of light by subjecting such a ray of light to an electric field [11,12]. According to results of his experiments, he found that
https://doi.org/10.1016/j.asej.2019.10.014 2090-4479/Ó 2019 THE AUTHOR. Published by Elsevier BV on behalf of Faculty of Engineering, Ain Shams University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Please cite this article as: S. Abdelhady, Innovative definition of nature of the nerve impulses, Ain Shams Engineering Journal, https://doi.org/10.1016/j. asej.2019.10.014
2
S. Abdelhady / Ain Shams Engineering Journal xxx (xxxx) xxx
the magnetic field can indirectly influence the behavior of such electrified light wave that means it is converted into electric current [13]. The influence or effect that Faraday observed is now known as Faraday’s rotation because his experiment illustrated the rotation of an electrified ray of light by the action of magnetic field, whatever the magnet’s configurations are, as seen in Fig. 1 [14]. According to the found results of Faraday’s experiment; the electric current may be interpreted as electrified electromagnetic wave or as an electromagnetic wave which has an electric potential [15]. Such interpretation is visualized in Fig. 2 by casting the Maxwell’s wave equations into an energy frame of reference where the time coordinate ‘‘t” in the wave equations is replaced by entropy ‘‘s” which is mainly a function of time and energy [15,16]. So, we get the following form of the modified Maxwell’s equations defined by three coordinates: the electric field E, the magnetic field H, and the entropy S as follows [17]:
! 1 @2 r 2 2 E¼0 c s 2
ð1Þ
! 1 @2 r 2 2H¼0 c s 2
ð2Þ
Fig. 2 shows also a graphical representation of the flowing electric and magnetic energies in an electromagnetic wave which can be estimated by the absolute value of the sum of the areas swept by the electric wave and the magnetic wave as follows [18]:
Z 2p
Fig. 2. Representation of flow of Electromagnetic waves in Energy frame of references composed of the energy coordinates: E-H-s coordinates, where the flow of the electric wave is shown in an E-s plane and the flow of the magnetic wave is shown in an H-s plane [18].
vector of the space coordinate and the angular velocity of the moving wave and u is the phase shift of the wave. The stated solution of Maxwell’s equations defined by the Eqs. (4) and (5) is represented graphically in Figs. 3A and 3B [18]. Fig. 3A represents a flow of negative charges where the electric wave is oscillating around a nega
ð3Þ
tive potential (D E). Similarly; Fig. 3B shows the flow of positive electric charges in the form of electromagnetic waves of positive
Eq. (3) determines the energy flow per wave, or the energy of the
electric potential (+D E) in a frame of energy coordinates E, H, and S. Both figures show visualization of ionized photons or electric
h¼
ðjEdSe j þ HdSmag: ÞJoule=wave
0
photon, denoted as ‘‘h.” The first integral in the R.H.S. in this equation represents the imparted electric energy of zero electric potential and the second term represents the imparted magnetic energy of zero magnetic potential per wave [18]. The sum of both energies is the quantized energy per wave ‘‘h } Joule/wave which is known as the energy of a photon [18]. According to such representation of the energy flow in an electromagnetic wave; it was possible to visualize the electrifying of the light in Faraday’s experiment as if the light gains a negative or a positive potential during its passing through an electric field. In other words; the electric current is considered as a special electromagnetic wave whose electric energy gained a negative or a positive potential during its electrifying process [18]. Such wave is described mathematically as a special solution of the modified Maxwell’s equations which have a permanent electric potential,
charges as electromagnetic of energy “ h” Joule=wave whose elec
tric potential is negative or positive of the value ‘‘þ= D E.” This means that the electric potential of the flowing current or charge is variable [19]. Considering the electric current as electromagnetic waves
whose energy has electric potential ‘‘þ= D E” paved the way to an innovative definition of electric current that deletes confusions in electromagnetism caused by the traditional definition of electric current as flow of electrons as shown in pevious articles [19]. However, the fact that light and electromagnetism waves or electric current are related had paved in the past a way for Maxwell’s
positive or negative, of the magnitude ‘‘þ= D E } as follows [19]:
Eðr; sÞ ¼ E cos ðkr þ xs þ uÞ þ = D E
ð4Þ
Hðr; sÞ ¼ Hcosðkr þ xs þ uÞ
ð5Þ
In these equations; r and s are the space and entropy coordinates; E and H are the electric and magnetic potentials, k and x are the unit
Fig. 1. Rotation of an electrified ray by a magnetic field (18).
Fig. 3A. Flow of negative electric charges as flow of electromagnetic waves of –ve potential where the electric energy in the E-s plane is oscillating around the negative potential ‘‘D E” [18].
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Fig. 3B. Flow of negative electric charges as flow of electromagnetic waves of –ve potential where the electric energy in the E-s plane is oscillating around the negative potential ‘‘+D E” [18].
entropy (s) brilliant theoretical demonstration of the definition of thermal radiation as electromagnetic waves, and their identity with light [20]. Additionally; the Tesla’s discovery of ‘‘Radiant energy” can be also interpreted as normal radiation of electric energy or as electromagnetic waves of electric potential from the Tesla’s tower [21]. Tesla’s experiment is found similar to the discharge of accumulation of electric charges as electrified electromagnetic waves from clouds during the lightening [22]. These results and foundations prove the truth of interpreting the electric current as electromagnetic waves of electric potential [23]. Such innovative definition of electric current succeeds also in deleting the ‘‘duality confusion” and represents a clear definition of the nature of electric charge as a special electromagnetic wave [24]. Researchers applied such clear definition of the electric charge in many applications as it wasn’t clearly defined in literature [25]. 3. A nature of the nerve impulses Recent observations of the neuroscientists defined the nerve impulses in general as electrical signals that travel down an axon or as an electric wave forced by an ‘action potential’ [26]. Such definition of the nerve impulse is directly consistent with the previously introduced definition of electric current as flow of electromagnetic waves of electric potential [23]. Neuroscientists rejected such definition of the nerve impulses as electric current since the electric current had been defined as flow of electrons and they have common understanding of the impossibility of flow of electrons through organic fibers [27]. However; the flow of the electric current through a patch from the cell membrane was recently measured and we get the description of fully activated current-voltage characteristics of such patch [28]. These measurements prove the possibility of flow of electric current or charges through the neural system or the ability of the cell membrane to conduct the nerve impulses as electric current [29]. Similarly; there are research teams and technologists who succeeded in pumping electric energy through optical fiber system [30–32]. Such results confirm the possibility of flow of the nerve impulses, as electric current, through the axon [33] Fig. 4 shows the nerve impulse as an energy wave that has an electric potential, or action potential, that decays with time [34]. However, the horizontal axis in Fig. 4, which indicates originally the time, is replaced in the figure by entropy which is mainly a function of time [35]. Such modification shows the shaded area in Fig. 4 as electric energy that flows during a nerve impulse and estimated by the following integral:
Z
Eimpulse ¼
EdS
ð6Þ
Fig. 4. Decay of the action potential as function of entropy increase during the nerve impulse.
Eq. (6) evaluates the flow of electric energy per nerve impulse as defined by the hatched areas in Fig. 4. However; such energy can be evaluated also by the same integral of the electric darkened
energy, limited by the potential difference ‘‘D E,” in Fig. 3A or Fig. 3B. So, the definition of the nature of the flow of nerve impulse as electric current fits its observed description as electric signals which have electric potential, according to Fig. 4. However, its traditional definitions as ionic current or as action potential are confusing as the dimensions of these two terms are not consistent and both definitions haven’t the recorded wavy nature of the measured nerve impulses [36]. Additionally, the description of the nerve impulses as electric charge affords plausible explanations for measured thermoelectric features that accompany the generation and propagation of the nerve impulses through the neural system while its definition as ionic current limited our investigations to its electrochemical aspects only while it has defintely thermolelectric aspects [37]. 4. Thermoelectrical aspects of the electric current Thermoelectricity is concerned by coupled conversion of heat and electricity. Such phenomena are mainly characterized by the Seebeck effect which is defined as follows [38]:
S¼
DV DT
ð5Þ
According to the new definition of electric current, this coefficient relates the conversion of the thermal potential of the incident heat ‘‘DT,” into electric potential ‘‘DV” by the Seebeck effect. Thus it characterizes the conversion of the thermal radiation, as electromagnetic waves of thermal potential DT, into electric current as electromagnetic waves of electric potential ‘‘DV”[39]. Such definition of Seebeck effect is applied in many thermoelectric devices as thermocouples or thermopiles, thermoelectric generators, and photovoltaic cells [40]. In case of photovoltaic cells, the thermal potential of the incident radiation is converted into electric potential, by the Seebeck effect, when it crosses the p-n junction of the PV cell. Such electric potential is proportional to the thermal potential of the incident radiation by Seebeck coefficient, as constant of proportionality, according to Eq. (5) [41]. Scientists succeeded in manufacturing organic photovoltaic cells that means the possibility of the functioning of neural cells as photovoltaic cells as will be discussed later.
Please cite this article as: S. Abdelhady, Innovative definition of nature of the nerve impulses, Ain Shams Engineering Journal, https://doi.org/10.1016/j. asej.2019.10.014
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Fig. 6. Distribution of ions across the cell membrane.
Fig. 5. Movement of charge carriers in the photovoltaic cell [40].
The original discovery of the Seebeck effect and thermoelectricity was related to the neural system of a frog where the generated electric potential by dissimilar metals caused the frog’s muscles to contract [42]. Such thermoelectric phenomena are used also in design of thermoelectric generators which consist of a higher plate at high temperature ‘‘Th ” and a lower plate of low temperature ‘‘Tl ” as shown in Fig. 5. [43]. Both plates are connected by legs of two dissimilar materials which have different Seebeck coefficients:Heat flows across these legs by the temperatures difference‘‘ðTh Tl Þ” between the two surfaces of the module. The heat flow is converted into electric current due to conversion of its thermal potential into electric potential when crossing junctions by the Seebeck effect [43]. Scientists succeeded in production of organic thermoelectric generators that convert the flowing heat through the thermoelectric generator into electric current by the Seebeck effect [44]. 5. Thermoelectric aspects of the electric nerve impulses Soliton model and other neural models were used to study the found thermoelectric aspects of the nerve impulses during its generation and flow through the neural system [45,46]. However; these models were adhered to the definition of the nerve impulses as ionic current which restricted these studies to its electrochemical aspects only [47]. Recognizing the nature of nerve impulses as electric charges, it is possible to start a new approach in the field of nerve impulses to investigate some measured thermoelectrical effects of these impulses. As an example; it is possible to discuss the detected temperature difference of the neuronal cells and the higher temperature of the brain than the body where it consumes 20% of the body’s oxygen and energy [9,47,48]. So, we may think the generation of the nerve impulses as electric charge in the cell’s membrane by Seebeck effect that may convert the generated heat energy during the biochemical exothermic reactions in the stimulated cells into electric energy [49]. The similarity of distribution of the ions in the PV cell, as seen in Fig. 5, and in the neural sell, as found in Fig. 6, may indicate a new approach for investigating the generation of the nerve impulses as electric charge in the neural cells by similar mechanism of the PV cells [50]. Similarly; it is possible to investigate the transmission of the nerve impulses as flow of electric current directly by conduction across the cell membrane and along the axon [51]. Of course; the truth of such approach is in need to hard work and sophisticated studies to solve many ambiguities in the field of neurosciences.
According to the previously explained characteristics of thermoelectric generators, crossing the junctions of the legs of the generator converts the thermal potential of the flowing heat into accumulating electric potential and covert the heat flow into electric current [52,53]. Similarly; it is possible to think the action of the successive Sodium and Potassium channels connecting the inner side and outer side of the neural cells as the actions of legs of the thermoelectric generators [54]. This proposal represents a new approach to the generation of electric current in the neural cell. Such proposals are sustained by the success of scientists and technologists in manufacturing organic PV cells and thermoelectric generators [44,55]. 6. Conclusions According to an innovative definition of the electric current as flow of electromagnetic waves of electric potential; it was possible to recognize the nature of the flow of nerve impulses directly as electric current whose potential was traditionally defined as the ‘‘Action Potential.” Such recognized nature verifies the recorded features of the nerve impulses as an electric wave of electric potential while its definitions as ionic current or an action potential contradict such features. The introduced definition allows also the study of detected thermoelectric aspects of the nerve impulses and suggests thermoelectric mechanisms for their generation by Seebeck effect. References [1] Brown AG. Nerve cells and nervous systems. An Introduction to Neuroscience. 2nd ed. Springer, 2001. [2] Squire L et al. Fundamentals of neurosciences. 3rd ed. 2013. [3] Jewett Jr, Serway RA. Physics for scientists and engineers with modern physics. 7th ed. Thomson; 2008. [4] Sakmann B, Neher E. Patch clamp techniques for studying ionic channels in excitable membranes. Annu Rev Physiol 1984;46:455. [5] Hamill OP et al. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Eur J Physiol 1981;391:85. [6] Abdelhady S, Cheng C. Advanced thermodynamics engineering. 1 st edi. Scitus Academics; 2019. [7] Benjamin D et al. Thinking about the nerve impulse: A critical analysis of the electricity centered conception of nerve excitability. Prog Neurobiol 2018;169:172. [8] Ryuichi T et al. Detection of temperature difference in neuronal cells. Nature, Scientific Reports 2016;6:1. [9] Sheikholeslami M, Jafaryar M, Shafee A, Zhixiong L, Li H. fRizwan-ul, Heat transfer of nanoparticles employing innovative tabulator considering entropy generation, Elsevier. Int J Heat Mass Transf 2019;136:1233–40. [10] Sheikholeslami M. New computational approach for exergy and entropy analysis of nanofluids under the impact of Lorentz force through a porous media. Elsevier Comput Method Appl Mech Eng 2019;344(1):319–33. [11] Faraday M. Experimental researches in electricity, nineteenth series. Phil Trans R Soc Lond 1846;136:1.
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Salama Abdelhady A full Professor of energy systems in Aswan University, has obtained his Ph. D degree from Bm University in 1975, He was the co-Founder & Dean of the Faculty of energy engineering in Aswan University, he has many researches in the field of thermodynamics, heat transfer, energy conservation and renewable energy, led many projects in the field of reverse engineering and CSP, he is a member in the supreme committee of power engineering for three periods, he was a visiting professor in Lehigh university, he was the head of departments of power engineering in MTC, High Institute of Energy, CIC, and Heliopolis University.
Please cite this article as: S. Abdelhady, Innovative definition of nature of the nerve impulses, Ain Shams Engineering Journal, https://doi.org/10.1016/j. asej.2019.10.014