the neuromyth of the cerebral hemispheres

Michael Taylor
Michael Taylor

Global Courant 2023-05-08 18:03:35

The brain, like the rest of the body, is made up of billions of cells. Each type with a certain function, but all of them perfectly synchronized and connected.

Our brain is made up of two halves: the cerebral hemispheres. But contrary to what it may seem, they are not two isolated and independent structures: both are extraordinarily connected by a “wiring” that communicates them.

We are talking about the corpus callosum, made up of more than 200 million nerve fibers that carry information from one hemisphere to another.

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This organization makes it possible to carry out and coordinate all the functions -many of them very complex- of the nervous system. And for this, the hemispheres share the work.

Getty Images It is wrong to believe that depending on which hemisphere is dominant in a person, they will be better at math or painting.

interconnected offices

Think of a large office building for the same company.

In it we will find different plants, with different departments, with different divisions, with different people working in each of the areas.

Each section has a function, but they are all related.

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Not only that, but they are also closely connected, since the proper functioning of some depends on what the others do.

Getty Images The corpus callosum, highlighted in red in the illustration, is made up of more than 200 million nerve fibers that carry information from one hemisphere to another.

The cerebral hemispheres work in a similar way, dividing up the work to be done. This means that although both halves are involved in a specific function, one of them may be more involved than the other.

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It’s just like the billing process in a large company: although the billing department carries all the weight of the operation, other sections must do their share of work to complete the process. For example, the shipping department that will send the invoice to its recipient.

The hemispheres are not a destination

And this is where the myth begins: “The brain is divided into two halves, and depending on which side we use the most, we will have some abilities or others.”

This theory, called “hemisphere dominance,” argues that if you’re good at math, language, or logic, it’s because your left hemisphere is dominant.

And if you are an artistic person with a gift for painting or music, then the right prevails.

This also contributes to misclassify people into two types: objective, rational and analytical or passionate, dreamers and creative. Nothing is further from reality.

There is no dominant hemisphere

Getty ImagesSometimes people are mistakenly classified into two types: objective, rational and analytical or passionate, dreamy and creative. Nothing is further from reality.

The myth probably originates from the meeting of the Paris Anthropological Society in 1865.

The culprit could have been, perhaps unintentionally, the French doctor Paul Broca after assuring that “we speak with the left hemisphere”, referring to the fact that the brain regions with the greatest involvement in language function are on that side.

The fact that the bulk of a specific function falls on one hemisphere, as is the case with language and the left half of the brain, does not imply that in a person with greater linguistic capacity that hemisphere dominates.

For example, when a singer memorizes the melody and lyrics of a song, the functions related to verbalizing the lyrics are located on his left side, but he will use his right side to express the musicality of the song. It is a team effort.

Evidence that disproves the myth

We find a multitude of studies in this scientific field, such as some that have come to examine images obtained by magnetic resonance imaging of the brains of more than a thousand people.

Their results show that we all use both hemispheres equally, although the activity registered in one and the other will depend “on what we are doing.”

It has also been shown that the side of the brain used for an activity might not be the same for everyone: analyzes show that there is variability between individuals as to which area or half is used for a particular action.

The myth of the dominance of the hemispheres is still very present today; in part, because there are still many unknowns about how the human brain works. The more it is investigated, the more we realize its complexity.

Getty Images The hemispheres of the brain are not two isolated and independent structures.

So, when the arguments that try to explain this complex functioning are exposed, they continue to lend themselves to simplistic interpretations such as that the functions are scrupulously segregated into brain areas and hemispheres.

If true, an injury to one of these highly specialized areas would cause that functional area to cease to be useful to the affected person.

However, this is not entirely the case and our nervous system maintains a certain plasticity.

In fact, it has been described that in people who lose a sense, such as sight, their brain area in charge of processing that sense and which no longer receives visual information, adapts to, in some cases, improve the perception of others, such as the touch.

This phenomenon improves the learning of tactile reading of the Braille alphabet, for example.

smoke sellers

The usual take advantage of this ignorance (scientific and social) of the entire functioning of the brain. Those who, using pseudoscientific language, with explanations and solutions for everything, want to take advantage of the uncertainty of the most vulnerable.

For example, making people believe that we can decide which hemisphere to use to modulate our abilities, capacities, personality; or the way in which we face the vicissitudes of life.

In addition, as is the case with other fields such as human health, neuroscience has not been spared from the propagation of myths and hoaxes through social networks.

However, although there is still uncertainty about some aspects of the functioning of the human brain, what we are sure of is that a person’s talent and personality are not determined by the dominance of one hemisphere over the other.

And by the way, it should also be pointed out, trying to avoid anthropocentric attitudes, that we are not the only animal with compartmentalized brain functions.

Getty Images If we mistakenly believe that there are “right-brained” students -much more creative- or “left-brained” -more analytical-, we are pigeonholing them into those categories.

pigeonholed students

Supporting the myth of the dominance of the brain’s hemispheres is dangerous in many ways. Especially in the field of education, since it limits the opportunities for learning and development of students.

If we mistakenly believe that there are students who are “right-brained” -much more creative- or “left-brained” -more analytical-, we are pigeonholing them into those categories.

This limits their learning opportunities, limiting their interests and preventing them from developing in other disciplines, which reduces their future career paths.

In short, no hemisphere is more important than the other and both function as a unit. What is certain is that brain activity is not symmetrical and varies between people.

*This article was originally published on The Conversation. You can read the original version here.

José A. Morales García is a scientific researcher in neurodegenerative diseases and professor at the Faculty of Medicine of the Complutense University of Madrid. Conchi Lillo is a tenured professor at the Faculty of Biology and a researcher of visual pathologies at the University of Salamanca.

the neuromyth of the cerebral hemispheres

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