Hemispheric specialization: what it is, characteristics and operation

The human brain is divided by the sagittal fissure into two halves that can be clearly differentiated and are known as the cerebral hemispheres.

These hemispheres are interconnected through bundles of neuronal fibers that belong to the body. callous and, although at first glance it seems that both hemispheres are symmetrical, the truth is that they are not are.

These differences between both hemispheres give name to the hemispheric specialization, and will be explained in more detail in the next section, but first a brief review will be made of what is has investigated hemispheric specialization, with the aim of knowing what this discovery.

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What is hemispheric specialization?

What is known as hemispheric specialization is the set anatomical and neurochemical differences, in addition to the set of different functions that the left hemisphere performs with respect to the right and vice versa. Hemispheric specialization is also known by the concept of lateralization.

Lateralization is made up of the functions and processes that are specific to each hemisphere and, therefore Therefore, the capabilities that are predominantly realized across a hemisphere would be said to be lateralized.

The hemispheric specialization, or lateralization, of some brain functions is based on the idea that there are specific regions in the brain that are responsible for carrying out specialized actions.

Another relevant concept in the field of hemispheric specialization is laterality, which should not be confused with lateralization. Laterality is the predominance in the management of the right extremities or, on the contrary, those of the left part of the body. For example, having a right laterality is what is colloquially known as “being right-handed” or, “being left-handed”, in the case of having a left laterality; having a majority of right-handed people.

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Differences between both hemispheres of the brain

In this section we will see some of the actions that each hemisphere performs laterally, as well as those that are performed through interhemispheric intervention.

1. Right hemisphere specialization

The right hemisphere is responsible for controlling and receiving the sensations from the left side of the person's body. According to the most accepted theories about hemispheric specialization, the right hemisphere is capable of processing the information that reaches you in a global and unsystematic way, emphasizing spatial and visual relationships. For this reason, the right hemisphere is considered as the creative and intuitive part of the brain.

This hemisphere allows us to perform skills such as having a holistic or global thinking in our mind, which is It is based on having abstract ideas and also on being able to see globally a set of elements that are related to each other. Yep. For example, when painting a picture, we have the ability to imagine an image as a whole and then proceed to paint, step by step, each of its component parts).

The right hemisphere too It enables us to have the capacity for intuition, to capture the non-verbal signals that another person transmits to us, to visualize the emotions expressed by others, play our artistic and musical creativity and fantasize.

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2. Left hemisphere specialization

The left hemisphere controls and senses the sensations of the right body part.

The left hemisphere performs information processing in a gradual, analytical and systematic way. This hemisphere emphasizes episodic or temporary relationships. For these characteristics it is known that the left hemisphere makes up the analytical and rational part of the human brain.

The left hemisphere is the part of the brain that allows you to carry out logical reasoning, solve problems and mathematical calculations, carry out linear and sequential thoughts, thoughts through language and recall events from the past, as well as think about the future.

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3. Interhemispheric integration

There is scientific research that has discovered that there are also actions that are carried out through the mediation of both hemispheres. This is carried out through various communication channels that are found in the corpus callosum and that allow them to be interconnected.. These types of operations, which involve both hemispheres, are known as hemispheric integrations.

Interhemispheric integration comes into operation when performing certain tasks, for which it is necessary that there be this interaction between specialized regions that are in both hemispheres of the brain.

It is known that when carrying out activities, which have normally been attributed to hemispheric specialization, it has subsequently been possible to verify that, even to a lesser extent, the other hemisphere also intervenes.

For example, when it came to understanding a metaphor or a saying, as they were linguistic reasoning tasks, it was known that the left hemisphere was involved in this; however, it was later discovered that the right hemisphere is also involved.

The same goes for visuospatial skills (p. g., differentiate between left and right), which are typically associated with the right hemisphere, although the left hemisphere also participates.

On the other hand, it has been found in research that some people who suffered a serious injury in one of the hemispheres, presented certain difficulties when processing the information. For example, patients who had a lesion in the right hemisphere have difficulties in attending to the global shape of objects; while those who had a lesion on the left, were unable to pay attention to the details of the objects, but they could identify the complete shape of the object.

In this way, when we analyze an image, such as an artistic painting, we need the coordinated work of both hemispheres. The right hemisphere would allow us to visualize the image represented in the painting in a global and harmonious way, while thanks to the hemisphere left, we could appreciate the nuances of the image, such as the gestures of the characters that are represented, the clothes and many others details.

The following section will briefly explain how the current knowledge regarding hemispheric specialization was reached.

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Historical review of the discovery of hemispheric specialization

The specialization of each hemisphere It arose as an idea around the year 1860, as a result of the discovery of the French doctor Paul Broca, who found that the left hemisphere was essential for humans to process language.

This happened when he was treating a patient with a lesion in the left hemisphere and, therefore, he had serious difficulties to speak, being able to say only the word “so”. Despite this he was able to understand the language heard, showing that he could follow simple commands.

Later, after having seen multiple cases similar to the one previously reported, he was able to observe that in all of them there was a lesion in the inferior prefrontal cortex of the left hemisphere, the area later known to involve the production of the speaks. For this reason it was baptized as Broca's area. Thus, a condition in this part of the brain is termed as Broca's aphasia.

The discovery about the area of ​​the brain that allows the production of speech was confirmed by Karl Wernicke, a psychiatrist and neurologist of German origin, who also discovered another area located in the left hemisphere, more specifically in the temporal lobe that, being injured, prevented the patient from understanding language, despite the fact that he was able to articulate sentences simple. Later, this area was named as Wernicke area. When this area is injured, the patient's condition is known as Wernicke's aphasia.

The English neurologist John Hughlings Jackson studied different phenomena in which one hemisphere dominated mental function with respect to the other, calling these cases brain dominance. Supporting in this way the ideas of Broca and Wernicke, who had shown that the understanding and production of language was based on a dominance of the left hemisphere.

In the 1920s, English neuropsychologist Brenda Milner discovered that a lesion in the temporal area of ​​the hemisphere law caused in the affected people the inability to assimilate new memories in the memory, despite the fact that cognitive abilities such as perception, language and reasoning functioned normally.

Roger Sperry conducted the research that was instrumental in promulgating the theory of hemispheric specialization. His investigation began with a World War II veteran who had been impacted on his head from a bomb blast and, as a consequence, suffered continual attacks of epilepsy. So the surgeons who operated on him decided to cut the corpus callosum from his brain and the epileptic seizures disappeared.

However, despite not having more epileptic seizures, he cannot get rid of some side effects. His right hemisphere was the one that suffered from the operation and, as a result, the patient was not able to control the extremities on the left side. On the other hand, he could control the right limbs and was also able to understand language, since this function is handled by the left hemisphere.

It is from Sperry's discovery that more emphasis began to be placed on the hypothesis that deduced that each hemisphere and each of its areas are specialized in specific functions, without neglecting the functions of interhemispheric integrations. This is when he began the exhaustive work, which continues to this day, of researching about the functions performed by the areas and hemispheres of the brain, one of the greatest unknowns about the study of the human being.