This PART C introduces a new theory of the neural system based on electrolytics. It replaces the previous ionic theory in use for the last 50 years. The previous theory depended on the ionic permeability of the membrane wall of neurons and an independence principle related to the flow of positive ions through that membrane. Current data shows that the intrinsic cell membrnae is totally impervious to ions because of its hydrophobic core and the independence principle has never been confirmed.
In order to understand the overall operation of the animal eye, it is necessary to understand the operation of the neurons of the eye. The next three chapters will provide this foundation. These chapters were not envisioned at the start of this work. However, they became crucial to the understanding of the visual system as a whole. The concepts to be presented may appear foreign and radical to the visual science and neuroscience communities. A few words of introduction are appropriate. Because of the unexpected importance of this PART to the overall work, these "few" will be more extensive than in the Introduction to other PARTS of this work. They more closely represent an Introduction to a separate text.
This work presents a functional description of the neuron that provides a foundation underneath the current morphological descriptions of the literature. The morphological description, limited primarily to the histology of the neuron is not adequate. The functional description assimilates the cytological (internal morphology), electrical, topological, and relevant metabolic data related to the neurological system in order to provide the first comprehensive description of the operational neurological system. A major result of this replacement is the relegation of the Soma to a primarily housekeeping role. The principle functional role becomes that of the Activa, the active electrolytic semiconductor device(s) defining the performance of the individual neuron, and ultimately the entire system. With the recognition of the Activa, found at all interfaces between neurites and axons, as the primary component of the neurological system, the performance of the overall system is explained in a more direct and detailed manner.
The entire family of neuron types is seen to evolve in an orderly manner from a simple original (non-neural) cell.
One result of this work is probably going to be a paradigm shift in the fields of neurology and vision research. A comprehensive and precise all-electrolytic description of the neural system is now available.
The PART is divided into three Chapters in order to differentiate between the basic concepts involved in the description of the electrical properties of the neuron and the broader description of the various electrical and morphological configurations found in the various types of neurons of the visual portion of the animal CNS.
Chapter 8 focuses on the basic sciences and elements associated with a fundamental neuron. Even this fundamental neuron is subdivided for discussion into a basic and a second order neuron. Both transistor action within the neural system and the need for explicit electrical power supplies to support this action is introduced. The proposition that a conventional synapse is actually an active electrolytic device is introduced.
Chapter 9 discusses the characteristics and properties of individual classes of neurons. It begins with the simplest, the bipolar neuron, and proceeds to the horiziontal and amercine cells, the photoreceptor cells and the ganglion cells. The Chapter includes a preliminary "data sheet" describing the electrical performance characteristics of each type of Activa involved in the visual process. These data sheets are works in progress and subject to expansion as a result of additional laboratory investigation.
Chapter 10 assembles the material from the first two chapters and develops the more complex relationships within and between neurons. It also develops the morphology of a given type of neuron based on its underlying functional requirements and resulting functional elements. A major section develops the electrical characteristics of various neurons as typically observed through electrophysiological experiments. It is shown that much of the inconsistency encountered in these experiments can be removed by more careful definition of the experiment and the experimental conditions employed. An alternate explanation of the mechanisms related to the "ion-pump" is provided. The relationship between ion-pumping and the unique non-dissipative resistance discussed below is demonstrated.
This material provides an alternate hypothesis to the operation of the neuron compared to that found in the current literature. Its claim to authenticity is based on its ability to properly and adequately describe the operation of a wide variety of actual neurons. Its fundamental proposition is that the neuron incorporates at least one active three terminal device, as opposed to a passive two terminal device such as a single membrane. The corollary to this proposition is that: failure to experimentally control this third terminal leads to spurious results, which are influenced by the uncontrolled variables associated with this terminal. This lack of control frequently results in reports of "Spontaneous" neuron output. A second proposition is that the transfer of charge is the basic signaling mechanism in the interneurons and the potential associated with that charge may be misleading since the underlying impedance may not be understood. The circuit diagrams presented here are of actual neurons (to the level of detail required by the discussion). These circuit diagrams should not be considered "equivalent circuits". The symbology used is man made; but the circuits these symbols describe are those of the actual neurons in animals.
This approach is consistent with the cautious statement by Gutmann, Keyzer & Lyons: "Solid state events involving conduction are evident in animate aggregations and may well be an essential characteristic of life, which may be an electromagnetic phenomena. A growing body of reviews and texts is available to support these views." Amen. This approach also solves one of the major problems they associate with organic semiconductors. The biological materials of the neurological system are all transparent liquid-crystals and easy to characterize compared to the generally amorphous organic semiconductors on which the above authors have concentrated.
It is not appropriate to present a comprehensive treatise on the detailed nature of the neural membranes of interest here. Only the pertinent parameters and general features will be discussed in order to provide the necessary structure to the overall vision process. However, even this treatment presents a vast collection of new experiments that can be performed to further the basic understanding of both membranes and neurons.
It appears that the development of the current literature of neurons at the membrane level has been seriously restricted because to a number of ground rules set by the physical chemists in their analyses. To maintain a tractable mathematical environment, they have generally restricted their analyses to electrolytic environments consisting of a single, symmetrical membrane separating two similar low concentration electrolytes, with a minimum number of ionizable atoms in each, under equilibrium conditions. These are not the conditions found in a neuron. Furthermore, the biophysicists have chosen to continue (since the 1950's) to treat the neuron as electrically passive except for the outer membrane of the axon which has been considered a 2 terminal active device. From a system electro-physiologists perspective, this is quite limiting. It does not allow a broad enough view of the overall neuron. By broadening this perspective and treating the overall neuron as containing one or more active devices, which are typically 3 terminal devices, a much more attractive model of the neuron appears based on not only the exterior membrane of the axon but also the internal junction between the dendrite and the axon, an Activa, and an additional structure, the poda which has only been hinted at in the current literature.
To understand the neuron from this perspective, the physical chemistry of intimate asymmetric membrane pairs immersed in three different high concentration electrolytes operating under non-equilibrium conditions must be considered.
If the physical chemistry framework is broadened to consider these possibilities, the external membrane of a single axon or dendrite is seen to take on the role of a simple single layer asymmetrical membrane separating two high concentration electrolytes under non-equilibrium conditions (and it is passive!). This non-equilibrium electrolytic condition provides a framework for explaining the non-linear impedance characteristic as well as the various ion pumps frequently proposed for incorporation in this "membrane system". This electrolytic cell approach also provides the explanation for the non-dissipative, reversible thermodynamics of the neuron which accounts for its remarkable thermal efficiency--no significant energy is lost as heat!!!
By bringing two of these membranes into close proximity, under non-equilibrium conditions, another unique (startling) phenomena is encountered, transistor action. The details will be presented below.
The literature of electrochemistry, particularly that portion found in textbooks, is highly inconsistent in both concepts and terminology. Furthermore, many if not most mathematical analyses invoke a variety of assumptions to make the mathematics more tractable. These assumptions are frequently not highlighted. A specific area of concern is in the area of and differences between the Nernst, Donnan, and Goldman equations (the latter sometimes modified and described as the Hodgkin-Huxley-Goldman equation). The serious investigator should be sure he understands the specific conditions which apply to the generation of each of these equations. As a starting point, the fact that the membrane involved is semipermeable to at least one, but not all, ionic species present should be recognized. Gutmann and Keyzer provide a brief comparison and site the appropriate references. To scope the situation, keep in mind that Nernst and Donnan investigated equilibrium conditions whereas the later investigators where investigating steady state conditions. There is a big difference between the two conditions when discussing neurons. For purposes of this work, a third condition will be introduced, non-equilibrium and non-steady state conditions.
All of the equations developed by the above authors were developed for low concentration solutions. The plasmas associated with neurons are so concentrated as to be at least very viscous if not actually in the liquid crystalline state. Understanding the operation of the neuron requires an understanding of the liquid crystalline state of matter.
In the subcategory of electrochemistry commonly described as electrolytic chemistry, it is also very important to understand the differences between reversible and irreversible thermodynamic processes and how to recognize them. In a reversible electrolytic process, an impedance may be specified which is related to a chemically reversible event. To assign this impedance to a resistor is misleading. A resistor is an electrical component that dissipates electrical energy when a current passes through it. The result is the generation of heat. This action is at the root of the Carnot Cycle and it involves an irreversible process. The impedance involved in a chemically reversible electrolytic process, such as the recharging of a lead acid battery, does not dissipate electrical energy and does not generate heat. This impedance represents the conversion of electrical energy into retrievable chemical energy. To distinguish this type of reversible impedance, that is not a resistor (or a reactance) in electrical terms, it is suggested that it be indicated by a different symbol than R. The logical choice is to use the last letter in the Cyrillic alphabet, yau, and represented by the mirror image of R. Until a way is found to print this character within an English language HTML document, the character ¶ will be used. This allows one to write an equation of the form:
V = iR + i¶
where the iR term is resistive and thermodynamically irreversible while the i¶ term is thermodynamically reversible and therefore ¶ is not a resistor within the terms of Ohm's Law. Specifically, the above equation is a proper description within Kirchoff's Laws but it is not a proper description within Ohm's Laws. The power dissipated in the above equation is Pd = i2*R and not i2*(R +¶). The power stored in chemical form in the above equation is Ps = i2*¶. Note however, the current related to the stored energy is not in quadrature with the current related to the resistor.
This author will undoubtedly be accused of trying to circumvent the Second Law of Thermodynamics. However, the Law referred to normally is more properly named the Second Law of Irreversible Thermodynamics.
As will be seen below, the dominant impedances involved in neurons are of the non-dissipative type and this must be pointed out in any equations developed to describe neural processes from the electrical perspective. They are not linear devices but diodes. The variability of their terminal voltage as a function of current is inherent.
The discovery of the non-dissipative nature of the electrical signaling in the nervous system is a major, but totally unexpected result of this work. It is now possible to understand how so much information transfer can occur within the human cranium without causing excessive heat to be dissipated. In fact, virtually no heat is dissipated within the animal nervous system. The necessary change in entropy is carried out via chemical transformations.
As might be expected from the foregoing, this work will only be concerned with synapses and intra-synapses relying on electrical transport of charge (current). Chemically mediated synapses are not considered or discussed. The author has a strong predisposition that chemical synapses do not exist.
By integrating the electrical and morphological characteristics of the neural system, the physiology of the neuron can be presented in a new, complete, compatible and intellectually satisfying framework.
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