The existence of life is still a mystery for science. ”Despite the extraordinary diversity and complexity of neuronal morphology and synaptic connectivity, the nervous systems adopts a number of basic principles” [2]. In this chapter, we derive those principles in an explicite form from the first principles of science and we prepare that discussion in an abstract level. We prepare the concepts and principles which enable us to answer E. Schrödinger’s question concerning the role of physics. In the spirit of Johnston and Wu [2], we introduce the relevant major components of a single abstract neuron that still follow the basic principles when processing neuronal information, moreover, the abstract principles of how they cooperate, conceptually.
Quotation: ”Neurons are specially endowed with the ability to communicate precisely and rapidly with other cells at distant sites in the body. …Neurons have receptive dendrites at one end and a transmitting axon at the other. This arrangement is the structural basis for unidirectional neuronal signaling. …The cell membrane of neurons contains specialized proteins—ion channels and receptors—that facilitate the flow of specific inorganic ions, thereby redistributing charge and creating electrical currents that alter the voltage across the membrane.” [41], page 71.
Our motto is similar to the frequently cited saying ’Cherchez la femme’: Look for the charge, meaning ”no matter what the problem, some charge is often the root cause” (however, we consider also effects of the thermodynamics on charge, given that the charges are ions instead of electrons. Furthermore, we shortly consider the mechanical (including thermodynamic), optical, etc. consequences.). The expression comes from the novel The Mohicans of Paris by Alexandre Dumas and is frequently used in detective novels in the sense that there are always complications and unusual situations, but ”no matter what the problem, a woman is often the root cause”. Although, in most cases, the cause is seemingly different.
Similarly, the charge is the primary quantity when speaking about neural operations. We follow this line and explain how processes, that traditionally belong to different science disciplines, redistribute charges and create electrical currents, then discuss how the cell handles the electrical charge. We note, however, that the different charge carrier (ions instead of electrons) needs care: the ”slow current” shows unusual behavior and the needs using known laws in more or less different form. The details are described in Chapter 2, where the fundamental differences caused by the charge carrier are discussed. Exactly as formulated: ”Transient electrical signals are particularly important for carrying time-sensitive information rapidly and over long distances. These transient electrical signals—receptor potentials, synaptic potentials, and action potentials—are all produced by temporary changes in the electric current into and out of the cell, changes that drive the electrical potential across the cell membrane away from its resting value.” We show that, alhough the thermodynamic effects are inseparable from the electrical ones, an appropriate combination of the disciplines satisfactorily describe the observations. We consider that neurotransmitters, receptors and specialized membrane proteins only implement a kind of (time and energy-consuming) chemical/enzymatic decoupling of the signal transmission mechanism. The idea resembles opto-coupling in electronics: makes the signal transmission independent from the local potential value. Suppose neurons use galvanic coupling when the resting potential of one of the neurons equals the extracellular space. In that case, all connected neurons’ resting potentials are equal to that of the extracellular space. Without this decoupling, the death of one neuron would immediately lead to the death of the entire neural network. Furthermore, the neurons could not make independent signal processing.