Law of all or nothing: what it is and why it is important in neurology

Within physiology, there are different rules which are always followed and which help us to understand more easily the functioning of the organism.

One of the best known about the electrical activity of our body is what is called the law of all or nothing.. Let’s explore the specifics of this standard and its implications.

    What is the law of all or nothing and how does it describe neuronal activation

    When we talk about electrical transmission between neurons and from neurons to muscle fibers, we are always referring to action potentials as that little current that transmits information from cell to cell. In this electrical transmission of the action potential, two things can happen: that it happens completely throughout the cell, or that it does not happen, but will never happen in part. This is called the all-or-nothing principle or law.

    Therefore, the electric current will cross the whole neuron, from the dendrites that receive it, to the end of its axon, Which in some cases can even make counters. The other option, according to the law of all or nothing, is that this electric current is not transmitted at all, since the action potential has not been intense enough to pass from the preceding neuron to this one. There is no common ground for neural electrical distribution.

    Here the so-called threshold of excitability would come into play, and does the transmission of nerve impulses require a certain amount of current in each case (depending on the specific conditions of each case, as this is not not always a fixed number). If this threshold of excitability is not reached, the law of all or nothing would be respected and the electrical impulse would not be transmitted to the attached cell, thus ending the path of the electrons at that time.

    Another characteristic of the law of all or nothing is that, if the threshold of excitability is reached and therefore the action potential is transmitted, it will do so by traversing the whole neuron with a constant intensity, Without fluctuations. For this reason, either it occurs as a whole, retaining all its force, or it does not occur, without any other possibility.

    Associated pathologies: epilepsy

    We have seen the law of all or nothing explains one of the foundations of the electrical activity of our brain. The problem is when for various reasons, whether it is an organic disease, trauma, tumor or the effect of an external effect, among others, they cause us a imbalance in the functioning of neural electrical circuits.

    This would be the case, for example, with epilepsy, a neurological disease that can cause different symptoms both psychologically and physically, from seizures that are triggered by these electrical imbalances that we have mentioned in different areas of the brain.

    When this pathology exists and the electrical movement between neurons is governed by the law of all or nothing, action potentials of higher intensity than normal are generated in certain areas of the brain, Which excite the cell membrane of the next neuron and thus transmit the current, reaching the muscle fibers and causing spasms, whereas in other circumstances these action potentials would not have been so high and therefore would not have caused all this symptomatology.

    To correct this pathology, different methods have been shown to be effective, Being one of the most common uses of pharmacology, along with the so-called antiepileptic drugs. There are 8 different types, many of which focus on controlling the transmission of various neurotransmitters that are said to conflict with the electrical activity of the brain.

    But the ones that interest us, in terms of the law of all or nothing, would be those others who are designed to control neural electrical impulses. In this sense, we find, for example, these compounds whose effect is to block the sodium channels (responsible for electrical transmission) with repetitive action. Some of the most well-known drugs of this type are oxcarbazepine, carbamazepine or phenytoin, among others.

    Another of the pharmacological pathways used to reduce this problem is to try to block other sites of electrical transmission.Like the calcium channels of the T, N or L type. We also find others whose mission is to modulate the activity of the current h, which is activated by hyperpolarization. They all work in the line of the correction of electrical activity, governed by the law of all or nothing.

      Criticisms of the concept in the scientific field

      Although when we talk about the law of all or nothing we do it from the point of view of security which is a mechanism that works in all cases without leaving any choice to chance (for some reason it is a law! ), there are studies which, although they do not criticize the fact that the concept is wrong, because such a thing cannot be stated, they try to give a more complete view, With some brushstrokes that would change the original definition.

      This is the case of the study by Vaixell et al., 2014, carried out at the University of Manizales in Colombia. For these authors, the notion of law of all or nothing is explained in a way, in part, contradictory, or at least not in the most appropriate way. And to make such a claim, they base their study on the electrostatic process generated in sodium channels activated by action potentials.

      The authors of this study carefully explain the entire procedure involved in the action potential and how an electrical imbalance occurs in the membrane when it reaches a certain intensity, Which carries certain ions into the cytoplasm and triggers the transmission of electricity throughout the cell. So far, this is an observable process in which little discussion is needed.

      Where they want to go is that in the use of the verbal formula, law of all or nothing, is attributed (still according to the authors) a kind of decision-making capacity for which, according to the conditions of this cell In In particular, it may or may not be exciting with the action potential, and rather it is a matter that obeys higher rules, especially those of the electrical mechanisms underlying this whole process.

      They also criticize that this is called the law of all or nothing, in that the part of “nothing” is an irrelevant concept that does not provide any information, because it is not a phenomenon that occurs in its maximum or minimum measurement. (nothing, in this case), but it’s a question that happens or does not happen.

      Although part of the discussion centers on lexical questions, what the authors attach the most importance to is their concern for the apparent lack of importance which they believe is given to the mechanisms of both molecules and the transmission of electricity, As part of the concept of the law of all or nothing.

      It must be said that, although the said study exists in relation to this question, the truth is that the formula of the right of all or nothing has not been a cause of conflict beyond this point, because it is a subject. studied and accepted. Overall, with the exception of these few exceptions, it is considered that it does not give rise to any kind of confusion and that it summarizes in very few words the concept so clear that it seeks to express, we would therefore speak of very isolated and therefore an insignificant review.

      in conclusion

      We have studied in depth what are the keys to understanding the processes that are triggered during the transmission of electricity between a neuron and its neighbor (and among other types of cells, such as muscle) and the importance of understanding the law of all or nothing to know how the channels are opened (those of sodium and potassium, the most common) for this movement of ions of different charge which triggers the electrical passage between cell and cell, Provided that the voltage required for this is reached.

      It is essential to know this rule and all similar ones to be clear about one of the most basic mechanisms of the functioning of the nervous system, and the law of the whole. or nothing is certainly one of the most basic, so if we want to understand what is going on in our brain, it has to be very clear.

      Bibliographical references:

      • Bateau, J., Duc, JE, Bateau, JA (2014). All or nothing principle: a misinterpreted concept or a bad dogma? Archives of Medicine (Col).
      • Solís, H., López-Hernández, E., Cortés-Gasca D. (2008). Neural excitability and potassium channels. Neuroscience Archives.
      • Suárez RE (1994). Thresholds: contribution to the study of the excitation and propagation of electrical activity in biological tissues stimulated by external electrodes. Montevideo. University of the Republic.

      Leave a Comment