Important aspects of brain lateralization (A full guide)

In this blog post, we will talk about some important aspects of brain lateralization. You will learn how lateralization affects our brain, what our cerebral hemispheres are responsible for and how brain lateralization evolves in children.

What is brain lateralization?

Brain lateralization is the development of specialized functioning in each hemisphere of the brain or on the side of the body that each controls. The most obvious example of laterality is the use of the hand; It is seen in the tendency to use one hand or the other to carry out different activities.

Our brain is fascinating. Its power, its capacity, its complex structure and the functions it governs make it an organ, as well as vital, especially captivating.

French and Italian scientists have created the first complete map of the lateralization of brain functions, which establishes which functions are more characteristic of the left or right hemisphere of the brain.

The cerebral hemispheres are the two largest structures in the brain, the part of the central nervous system included within the skull. They are inverse and asymmetric to each other, and much research has been done so far to identify the “dominant” hemisphere of different brain functions, without an overall perspective on this cerebral lateralization. 

The results of this study, published in Nature Communications, demonstrate for the first time that decision-making, such as perception and action, as well as emotions, are more resonant for the right hemisphere, while symbolic (non-verbal) communication. It is based more on the left hemisphere. 

The conclusions have been obtained after analyzing functional and magnetic resonance images obtained worldwide for more than 15 years. From this information, the researchers identified four groups of extremely lateralized functions based on the brain region reflected in the images.

Thus, they appreciated that symbolic communication, which manifests itself in the language, reading, calculation, or language of deaf people, is highly lateralized in the left hemisphere of the brain.

However, functions related to perception and action, as well as emotions, are registered in the right hemisphere. Decision making also, but is based more on the regions of the right frontal lobe. This discovery is especially innovative because until now no asymmetry has been established between the hemispheres when making decisions.

The study clears an age-old question about the connections between hemispheres since it was not known whether the two hemispheres collaborate to process information more quickly or react separately.

The brain map found that the more lateralized the functions, the fewer the connections between hemispheres to perform a function, thus confirming the hypothesis that one dominant hemisphere for a function is poorly connected to the other hemisphere to be more efficient.

The cerebral hemispheres

Another conclusion that emerges from this study is that brain functions have been lateralized throughout evolution as the size of the brain has increased. That is, lateralization has been specializing in certain functions to ensure brain efficiency despite the increase in neuronal mass.

The researchers draw attention, however, to another not less relevant finding. This optimization by lateralization has been carried out at the expense of another evolutionary advantage: functional recovery after brain injury.

That means that, due to decreased connections between the hemispheres, it is certainly more difficult for the damaged hemisphere to overcome lost functions in the event of illness or accident.

The study sheds new light on a field of neuroscience that especially affects the typology and way of being of people since according to the cases, it is believed that most people have a dominant cerebral hemisphere.

If the right hemisphere predominates, people are imaginative and creative and more receptive to image learning. If, on the contrary, the left hemisphere predominates, people have a greater capacity for analysis and reasoning, as well as solving mathematical problems.

These characteristics mark not only the character of the people but also their professional orientation and social performance. The new research not only confirms the lateralization of the brain functions that mark our personality, but also that this specialization makes it difficult to connect with the other hemisphere that would allow creative people to be more rational, and imaginative people to be more realistic.

What is brain lateralization in the infant stage?

Crossed laterality in childhood

Simply put, laterality is the preference that we all have for using a part of our body. One of the clearest examples is the use of one hand over the other, so we find right or left-handed people, but also ambidextrous. Laterality is not limited only to the use of the hands and limbs, the same is also true of the ear and eye.

In the vast majority of people, the left cerebral hemisphere governs the right body half while the right hemisphere guides the left half. The reasons for this brain specialization are still unknown.

How brain lateralization evolves in children

Brain lateralization is a dynamic process that goes through different phases until approximately 6-7 years old it finally establishes itself. It is important that when the child reaches the age of compulsory schooling (6 years) he has acquired his lateralization.

The proper development of laterality is essential for correct learning of reading and writing, the elaboration of its body schema, the organization of right-left spatial references

Undifferentiation phase (0-2 years): This is a time when the child has no defined laterality. The little one discovers that he has two hands and that they belong to him. It is the stage in which he likes to grab and throw the objects he manipulates and he realizes that this allows him to interact with the environment.

Alternation phase (2-4 years): Period in which the child becomes an explorer, everything fascinates him and therefore he needs to go from one place to another and touch everything that is within his reach. If we look at it carefully we will see that it still uses both hands interchangeably to do any type of activity.

Automation phase (4-6 years): From 4 years, we will see how little by little the child automates his/her gestures. It is the moment when the child begins to use one side more than the other.

This way he will begin to look through a hole through the dominant eye, take the telephone receiver to the preferred ear, kick the ball with the dominant foot, pick up the writing pencil or a glass to drink with the hand that he will finally use.

As we can see, lateralization is interrelated with the set of motor functions and at the same time, it intervenes at all levels of the child’s development.

Laterality tips

There are different types of laterality:

Right-handed: where there is a cerebral predominance of the left hemisphere and right motor realizations.

Left-handed: when the right cerebral hemisphere is the one who guides and exercises the motor action of the left side in a dominant way.

False right-handed: those people who have been forced to perform tasks with the right when the left-handed was considered a disease. Fortunately, these kinds of beliefs have practically disappeared from our society.

Ambidextrous: left-handed for some activities and right-handed for others.

Crossed laterality: hand and the predominant eye do not belong to the same side.

How can we help children develop brain lateralization?

Activities that contribute to the development of a preferred hand are those that stimulate and help mature the brain pathways on both sides of the brain. Importantly, many of these activities should focus more on the movements and actions of the entire body rather than just the hands.

The movement that involves turning, rolling, falling, rocking and dancing stimulates the balance organs in the brain. These play an important role in telling the brain where the body is in space and what movements are necessary for posture, response to stimuli, and action.

Also, children need good balance and proper coordination for healthy brain maturation and dexterity development. Be careful not to overdo this type of activity. Children vary greatly in achieving specific skills, so you must respect their abilities and reactions.

Laterality determines the most developed side of the body in individuals.

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FAQ about brain lateralization

What does the lateralization of the brain mean?

Brain lateralization is the development of specialized functioning in each hemisphere of the brain or on the side of the body that each controls. The most obvious example of laterality is the use of the hand; It is seen in the tendency to use one hand or the other to carry out different activities.

What is lateralization and why is it important in the way our brain functions?

Simply put, lateralization is the preference that we all have for using a part of our body. One of the clearest examples is the use of one hand over the other, so we find right or left-handed people, but also ambidextrous. Laterality is not limited only to the use of the hands and limbs, the same is also true of the ear and eye.

What age does brain lateralization occur?

Brain lateralization is a dynamic process that goes through different phases until approximately 6-7 years old it finally establishes itself. It is important that when the child reaches the age of compulsory schooling (6 years) he has acquired his lateralization.

What is cross lateralization?

Cross lateralization refers to the cases where the predominant hand and the predominant eye do not belong to the same side.

How does lateralization affect the brain?

 The new research not only confirms the lateralization of the brain functions that mark our personality, but also that this specialization makes it difficult to connect with the other hemisphere that would allow creative people to be more rational, and imaginative people to be more realistic.

What is the left brain hemisphere responsible for?

The left brain hemisphere is responsible for language, reading, calculation, or language of deaf and mentally challenged people. 

Conclusions

In this blog post, we talked about some important aspects of brain lateralization. You learned how lateralization affects our brain, what our cerebral hemispheres are responsible for and how brain lateralization evolves in children.

Brain lateralization is the development of specialized functioning in each hemisphere of the brain or on the side of the body that each controls. The most obvious example of laterality is the use of the hand; It is seen in the tendency to use one hand or the other to carry out different activities.

Simply put, laterality is the preference that we all have for using a part of our body. One of the clearest examples is the use of one hand over the other, so we find right or left-handed people, but also ambidextrous. Laterality is not limited only to the use of the hands and limbs, the same is also true of the ear and eye.

In the vast majority of people, the left cerebral hemisphere governs the right body half while the right hemisphere guides the left half. The reasons for this brain specialization are still unknown.

If you have any questions or comments on the content, please let us know!

References 

The architecture of functional lateralisation and its relationship to callosal connectivity in the human brain. Vyacheslav R. Karolis, Maurizio Corbetta & Michel Thiebaut de Schotten. Nature Communications volume 10, Article number: 1417 (2019).

Groen, M. A., Whitehouse, A. J., Badcock, N. A., & Bishop, D. V. (2012). Does cerebral lateralization develop? A study using functional transcranial Doppler ultrasound assessing lateralization for language production and visuospatial memory. Brain and behaviour, 2(3), 256–269. https://doi.org/10.1002/brb3.56

Frontiersin.org – The Evolution of Lateralized Brain Circuits

Dana.org – Seeking the Right Answers About Right Brain-Left Brain

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