Cerebral hemispheres: myths and realities

About cerebral hemispheres it is common to hear phrases like these: “If you are a very creative person you use the right hemisphere a lot more” or “If you are an analytical person you use the left hemisphere more” … However, the whole relating to these two parts of the brain is a little more complicated than these simplifications.

In this article we will see what the cerebral hemispheres are, what are their characteristics and how they differ, since these components of the central nervous system allow us to understand much of what is happening in our brain, as they determine the operation.

    Cerebral hemispheres: what are they and how do they work?

    When observing a human brain, one of the most striking things is this type of crack that separates the two halves of it and goes from front to back.

    Its existence is not causal and gives clues to the functioning of the brain, a set of organs in which we try that the cerebral cortex (the outermost part of it, with roughness) occupies the greatest possible extension. Thus, the existence of the cerebral hemispheres allows more cerebral cortex to spread between them.

    Why has our brain evolved to give so much importance to the cerebral cortex? Indeed, it is in the cerebral cortex that most of the bodies of neurons are concentrated, that is to say their most important part, where the nucleus is located. The grouping of neuronal bodies forms what is called gray matter, associated with complex brain activity.

    In recent years, a multitude of courses, tests, e-books and books have emerged on social networks that tell us “the big differences between the use of one or the other hemisphere of the brain”, and even tips and exercises to achieve a perfect balance (sic) between the two hemispheres.

    However, it is necessary to consider: Is it true that we tend to use one hemisphere more than another? Is this conception necessary that each hemisphere have differentiated functions? To answer these questions, you need to know what cerebral hemispheres are, even if it comes from a basic definition.

    Anatomy of these hemispheres of the brain

    The cerebral hemispheres are the two structures into which the brain divides and are separated from each other by the interhemispheric cleft (or inter-brain cleft). These two bodies belonging to the central nervous system are very similar to each other, and are practically symmetrical to each other, although there are some differences in their proportions and in their folds.

    On the other hand, the hemispheres of the brain are connected to each other by the corpus callosum and other similar commissures; it is through these parts of the brain that it crosses information from one to the other.

    The anatomy of the brain and how it divides into two hemispheres gives us some clues about how this set of organs works.

    On the one hand, we know that the cerebral cortex exists because it is on its surface that neuronal sums accumulate, that is to say that in these areas the bodies of these nerve cells, their main structure and where its core is. The human brain has prioritized the cerebral cortex to give us more capacity to process information, and therefore the best way is to make the cortex have folds, to have more area, and the interhemispheric slit can be understood as a consequence of this phenomenon: it is still a very deep fold.

    But since all parts of the brain are needed from each other and cannot function entirely in parallel, deep in this slit are structures such as the corpus callosum, which act as a bridge between the two sides of the brain.

    Pocket neuroscience: oversimplifying

    It seems that this is already general knowledge for many people who the right hemisphere is related to the process and expression of emotions, Both internal and external (this hemisphere is related to empathy) while, on the other hand, the left hemisphere is responsible for language processing, rational logic and analytical capacity.

    However, this knowledge, although for some reason has taken root in the collective culture and everyone seems to take it for granted, is not entirely true. It is a widespread myth that has little or no relevance to reality. and with the scientific data available. Without going any further, the right hemisphere also performs functions associated with processing certain aspects of language, such as intonation and intensity.

    On the other hand, the brain has a great capacity to adapt to challenges, and each hemisphere is able to “learn” to. perform functions performed by parts of the opposite hemisphere if those regions are damaged. This faculty is called brain plasticity, and it shows us how the functioning of our brain is not frozen.

    Science and research to shed light

    The data and information extracted about the functional differences in the hemispheres of the brain comes from neurological studies from the early 1970s of patients who had a cut of the corpus callosum (the fibers connecting the two hemispheres) in shock surgery to treat the disease. ‘epilepsy.

    Some of the academics and researchers who have contributed the most to the study of the brain in patients without corpus callosum were psychologists. Roger w sperry I Michael Gazzaniga, Those who discovered that the two halves of the brain developed their processes independently and with equally differentiated dynamics.

    However, it should be borne in mind that in healthy people, the cerebral hemispheres are correctly connected by the corpus callosum, perceptual and executive processes develop in the brain as a whole, So that different regions and hemispheres of the brain share information through the corpus callosum.

    While certain areas of the brain focus more on certain functions, generally a very small part of the cerebral cortex is not completely irreplaceable: if it is injured, another will take care of the functions that have become “orphan”. And the same goes for the hemispheres of the brain in general.

    Currently, neuroscientists (neurologists, biologists and psychologists) are trying to understand how this complex coordination between the hemispheres is achieved. This is why theories such as cerebral hyper-modularity, supported mainly by evolutionary psychology and according to which the brain is a set of specialized parts working more or less in parallel, are little accepted by the scientific community. The brain is what it is because in it, millions of neurons coordinate with each other, Create activation models that should be understood as a whole.

    Creativity, right hemisphere. For sure?

    It should also be borne in mind that the type of daily life tasks which popular belief require “a particular hemisphere” do not fully fall under the left hemisphere / right hemisphere categorization.

    One of the skills with which it is easier to dispel the myth is creativity. It is even easier to assume that the creative tasks take place in the right hemisphere and the repetitive and analytical tasks in the right, the reality is that these tasks are more complex and involve the brain in a more holistic way than it could possibly be. expect it. the myth.

    In addition, “being creative” can take many forms, it’s too open a concept as if to lock in an easily recognizable task as a process in the human brain.

    In fact, there is a study that compares the brains of “literature” students (philology, history, art) with “science” students (engineering, physics, chemistry) … and the results are incredible. We tell you here:

    • Brain differences between “literature” and “science” students

    Studies on the subject

    Several studies point out that the right hemisphere plays a major role in times when we have great intuition. In fact, a study published in PLOS found that right hemisphere activity was highest when assessed subjects attempted to solve a task in an intuitive, with little time for thinking.

    Another investigation found that brief exposure to a clue that gave clues to solving a puzzle was more useful for the right hemisphere than the left hemisphere. The right hemisphere was activated more clearly, leading some of the participants to the solution of the task.

    In any event, it should be noted that the preview (The process of internalization or internal understanding) is only one aspect of creativity. For example, the ability to tell stories would be another creative side. Here we find an important schism: studies evaluating the influence of each hemisphere on certain tasks have revealed that it is the left hemisphere that is most involved in the process of inventing stories or tales, While the right hemisphere is responsible for finding an explanation for the story. This curious division of functions has been called the “performer phenomenon” by Gazzaniga.

    Simple myths that quickly creep into people’s minds

    In a general presentation on the cerebral hemispheres and their (not so) differentiated functions, Gazzaniga described, in an article published in Scientific American, the left hemisphere as “inventor and interpreter” and the right hemisphere as “veracity and literalism” . adjectives which they contrast with the popular design on each hemisphere.

    In any case, it is clear that hardly any cognitive process relies on very delineated parts of the brain. Everything takes place in an organic network of interconnected nerve cells, which do not understand the differentiations and closed categories established by human culture. That’s why we have to have this the differences between the cerebral hemispheres are relative, Not absolute.

    In conclusion: between simplifications, exaggerations and corners of reality

    Scientific evidence does not match the myth that the left hemisphere is related to logical processes and the right to the creative realm. If applicable, Why do people and even professionals in psychology or neuroscience do they repeat this mantra?

    One of the possibilities for understanding how a myth develops and consolidates itself in the collective culture is its seductive simplicity. People look for easy answers to questions that are pretty naïve to begin with: “What kind of brain do I have?”

    With a quick search on Google or on various social networks, a person without scientific knowledge and having this personal concern can find applications, books or workshops to “improve his weak hemisphere”. When there is demand, the supply does not take long to appear, even if the scientific support on which the question is based is rather questionable. As in this case, where the simplification rubs off this information on the falsity.

    Thus, it is difficult to combat a faulty belief system, as the complexity involved in the functioning of our brains cannot be summed up in a brief basic overview. However, psychology and mental health professionals and neuroscientists we must be in charge of reporting rigorously and refuting these myths and simplifications.

    Bibliographical references:

    • Bowden EM, Jung-Beeman M. (2003). Ah! The Insight experience correlates with the activation of the solution in the right hemisphere. Psychon Bull Rev. September 2003; 10 (3): 730-7. PMID: 14620371. Available at: https://www.ncbi.nlm.nih.gov/pubmed/14620371
    • Jung-Beeman, M., Bowden EM, Haberman J., Frymiare JL, Arambel-Liu S., Greenblatt R., et al. (2004). Neural activity when people solve verbal problems with vision. PLoS Biol 2 (4): e97. Available at: https://doi.org/10.1371/journal.pbio.0020097
    • Kandel, ER; Schwartz, JH; Jessell, TM (2001). Principles of neuroscience. Madrid: McGraw Hill.
    • Kolb, B., Whishaw, I. (2008). Fundamentals of human neuropsychology. London: Macmillan.
    • Ortega, FV (1998). Treatment of epilepsy. Madrid: Editions Diaz de Santos.
    • Salas, C., Broglio, C., Rodríguez, F. (2003). Forebrain evolution and spatial cognition in vertebrates: conservation through diversity. Brain, behavior and evolution. 62 (2): 72 to 82.
    • Singh, V. (2017). Anatomy textbook. New York: Elsevier.
    • Zuluaga, JA (2001). Neurodevelopment and stimulation. Madrid: Medica Panamericana.

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