Brain hemispheres: myths and facts

On the matter of brain hemispheres It is common to hear some phrases like these: "If you are a person with great creativity, you use the right hemisphere much more" O well "If you are an analytical person, you use the left hemisphere more"... However, everything related to these two parts of the brain is much more complicated than these simplifications.

In this article we will see what the cerebral hemispheres are, what are their characteristics, and how they differ, taking into account that these components of the central nervous system allow us to understand a good part of what happens in our brain, since they determine the functioning of this.

• Related article: "Parts of the human brain (and functions)"

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

When looking at a human brain, one of the things that attracts the most attention is that kind of crack that separates the two halves of it and that goes from the front to the back.

Its existence is not causal, and it gives clues about how the brain, a set of organs in which

It is intended 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 such importance to the cerebral cortex? This is so because it is in the cerebral cortex where most of the bodies of neurons are concentrated, that is, their most important part, where the nucleus is located. The grouping of neuronal bodies forms what is known as gray matter, associated with complex brain activity.

In recent years, they have emerged in social media multitude of courses, tests, e-books and books that explain "the great differences between using one or the other hemisphere of the brain", and even tips and exercises to achieve a perfect balance (sic) between both hemispheres.

However, it is worth considering: Is it true that we tend to use one hemisphere more than another? Is this conception accurate that each hemisphere performs different functions? To answer these questions, it is necessary to know what the cerebral hemispheres are, even if it is from a basic definition.

Anatomy of these hemispheres of the brain

The cerebral hemispheres are the two structures into which the brain is divided, and they are separated from each other by the interhemispheric fissure (or intercerebral fissure). These two bodies belonging to the Central Nervous System are very similar to each other, and are practically symmetrical between them, although there are some differences in their proportions and its 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 those parts of the brain where information passes from one to another.

The anatomy of the brain and its way of dividing into two hemispheres gives us some clues about the functioning of this set of organs.

On the one hand, it is known that the cerebral cortex exists because it is its surface that accumulates neuronal cells, that is, that in these areas the bodies of these nerve cells are piled up, their main structure and where their nurture it. The human brain has been giving priority to the cerebral cortex to give us greater capacity to process information, and for this the best way is to make the cortex have folds, to have more surface area, and the interhemispheric fissure can be understood as a consequence of this phenomenon: it is still a very deep.

But since all parts of the brain need each other and cannot operate entirely in parallel, at the bottom of this fissure there are structures such as the corpus callosum, which act as a bridge between both sides of the brain.

Pocket Neurosciences: Oversimplifying

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

However, this knowledge, although for some reason it has taken root in the collective culture and everyone seems to take it for granted, is not entirely true. It is a very widespread myth that bears little or no relation to reality. and with available scientific data. Without going any further, the right hemisphere also performs functions associated with the processing of some 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 capable of "learning" to carry out functions performed by parts of the opposite hemisphere if these regions are damaged. This faculty is called brain plasticity, and it shows us to what extent the functioning of our brain is not fixed.

Science and research to shed some light

The data and information extracted on the subject of functional differences of the hemispheres of the brain come from neurological studies from the early 1970s on patients who had a cut in the hard body (the fibers that connect both hemispheres) as a shock intervention to treat the epilepsy.

Some of the academics and researchers who contributed the most to the study of the brain in patients without corpus callosum were psychologists Roger W. Sperry Y Michael gazzaniga, who discovered that the two halves of the brain developed their processes independently and with differentiated dynamics.

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

Although certain regions of the brain are more focused on certain functions, usually a very small part of the brain cerebral cortex is not totally irreplaceable: if it is injured, another will take over those functions that have been left "orphans". 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 hemispheres takes place. That is why theories such as that of brain hyper-modularity, supported above all by evolutionary psychology and according to which the brain is a set of specialized parts that work more or less in parallel, they are little accepted by the community scientific The brain is what it is because in it, millions of neurons coordinate with each other, creating activation patterns that must be understood in their entirety.

Creativity, right hemisphere. Sure?

It must also be borne in mind that the type of daily life tasks that require "a specific hemisphere" according to popular belief, does not fully conform to the categorization left hemisphere / right hemisphere.

One of the easiest skills to disprove the myth is with creativity. Although it is easier to assume that creative tasks take place in the right hemisphere and repetitive and analytical tasks in the right, the reality is that these tasks are more complex and involve the brain in a more global way than one might expect if we believe the myth.

Also: “being creative” can take many forms, it's too open concept as if to cloister it in an easily recognizable task as a process within the human brain.

In fact, there is a study that compares the brain of "literary" students (philology, history, art) with "science" students (engineering, physics, chemistry)... Y the results are surprising. We explain it here:

• Brain differences between "literary" students and "science" students

Studies on the subject

Several investigations indicate that the right hemisphere plays a greater role in times when we have great intuition. In fact, a study published in PLOS found that the activity of the right hemisphere was higher when the subjects tested tried to solve a task intuitively, with little time for reflection.

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

Anyway, it must be clarified that the insight (the process of internalization or internal understanding) is just one aspect of creativity. For example, the ability to tell stories would be another creative side. Here we already find an important schism: studies evaluating the influence of each hemisphere on certain tasks have revealed that the left hemisphere is the most involved in the process of making up stories or tales, while the right hemisphere is in charge of looking for an explanation to the story. This curious distribution of functions was called "interpreter phenomenon" by Gazzaniga.

Simple myths that stick quickly in people's minds

In a general exposition 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 "truthfulness and literalism." Adjectives that contrast with the popular conception over each hemisphere.

In any case, it is clear that practically no cognitive process is based on very limited parts of the brain. Everything occurs in an organic network of interconnected nerve cells, which do not understand differentiations and closed categories established by human culture. That is why we must have to the differences between the cerebral hemispheres are relative, not absolute.

Concluding: between simplifications, exaggerations and corners of reality

Scientific evidence does not correspond to the myth that tells us that the left hemisphere is linked to logical processes and the right to the creative realm. If this is so, Why do people and even professionals in psychology orneuroscienceskeep repeating this mantra?

One of the possibilities to understand how a myth expands and consolidates in the collective culture is its seductive simplicity. People look for easy answers to questions that, from the outset, are quite naive: “What kind of brain do I have?”.

With a quick search in Google or in the different social networks, a person without knowledge scientists and with this personal concern you can find applications, books or workshops to “improve your weak hemisphere ”. When there is demand, the offer does not take long to appear, although the scientific basis on which the matter is based is rather debatable. As in this case, where simplification makes this information border on falsehood.

Thus, it is difficult to fight against an erroneous belief system, since the complexity involved in the functioning of our brain cannot be summed up in a brief basic outline. However, psychology and mental health professionals and neuroscience scholars we must be in charge of rigorously reporting and debunking these myths and simplifications.

Bibliographic references:

• Bowden E.M., Jung-Beeman M. (2003). Aha! Insight experience correlates with solution activation in the right hemisphere. Psychon Bull Rev. 2003 Sep; 10(3):730-7. PMID: 14620371. Available in: https://www.ncbi.nlm.nih.gov/pubmed/14620371
• Jung-Beeman, M., Bowden E.M., Haberman J., Frymiare J.L., Arambel-Liu S., Greenblatt R., et al. (2004). Neural Activity When People Solve Verbal Problems with Insight. PLoS Biol 2 (4): e97. Available in: https://doi.org/10.1371/journal.pbio.0020097
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