Blindness and the secret of brain flexibility / You will be surprised by this

When vision is temporarily unavailable, the brain may use areas normally associated with vision to process tactile information.

Research shows that the brain does not abandon the visual parts after blindness, but even within five days it resets them to process the sense of touch. The human brain is not a fixed and unchanging structure. Throughout life, this amazing organ continuously adapts to new experiences, learns new skills, and changes the way it processes information. But when one of the most important sources of perception, vision, is lost, how does the brain cope with new conditions?

The brain is made up of billions of nerve cells that communicate with each other through a complex network. These connections are not fixed and everyday experiences, learning and practice can change how they work.

For example, when a person learns to play a musical instrument, their brain gradually becomes more adept at coordinating finger movements, processing sounds, and remembering musical patterns. Part of this progress is related to changing the strength of neural connections and better coordination of brain networks.

Neuroplasticity is called this ability to change. The brain can strengthen frequently used connections, change the activity level of certain neural pathways and, under certain conditions, coordinate the organization of its networks with new needs.

When a person loses sight, the brain no longer has the information it used to receive from the eyes. This change can transform the activity of networks related to sensory information processing.

Of course, neural plasticity does not mean the brain's unlimited ability to compensate for any damage. The brain cannot freely replace every missing part or remove all the limitations caused by blindness. The degree of adaptation depends on various factors, including age, previous experiences, the state of neural networks and the duration of blindness.

One of the interesting questions about neural plasticity is how long it takes the brain to adapt to new conditions. Do the changes appear after years of blindness or can they start much earlier?

Research shows that some functional changes in the brain can occur in just a few days. The reason for this speed is that the brain does not necessarily need to build new neural connections for each change. Sometimes changing the way of using the pathways that already exist is enough to change the activity of a brain network.

The brain has the ability to change throughout life and can adapt to new experiences and conditions by strengthening or changing neural connections.

In contrast, some more stable adaptations may develop over months or years. Everyday experiences, learning new skills and repeating activities can gradually change the strength of neural connections and the way brain networks work together. Therefore, the adaptation of the brain to blindness is not a sudden and uniform event; It is a set of short-term and long-term changes that may occur at different speeds.

They were denied a visit. During this time, the participants were blindfolded and under the supervision of the researchers, they practiced tactile skills, including recognizing Braille characters.

After five days, the visually deprived people performed better than the control group in recognizing Braille characters. Examining their brain activity also showed that parts of the occipital region, which are usually associated with visual information processing, were more activated when performing tactile activities.

The researchers then temporarily disrupted the activity of this area by using transcranial magnetic stimulation. The result showed that this intervention reduces the performance of visually impaired participants in recognizing Braille characters; A sign that the area in question was involved in tactile activity. More interestingly, after removing the blindfolds, the change in activity recorded in the occipital region disappeared within about 24 hours.

This experiment showed that the adult brain can change its way of working much faster than previously thought. However, the observed changes occurred in people who were temporarily blind, and the results cannot be directly generalized to people who have lived with blindness for many years.

When we talk about brain reorganization, we might think of neurons starting to build a whole new network after blindness. But brain adaptation doesn't always require such a sweeping change.

To better understand this, imagine a city with several main and side streets. If one of the main routes is closed, drivers can use side streets. At first, there is no need to build a new path; Pre-existing streets can handle more traffic.

Something similar happens in the brain. Some neural connections that previously had limited activity may become more prominent after changing sensory inputs.

One of the possible explanations for this phenomenon is the change in the balance between excitatory and inhibitory activities in neural networks. Under normal conditions, the activity of some pathways is limited by inhibitory messages. Changing sensory conditions may alter this balance, allowing existing connections to have a greater influence on brain activity.

The brain does not always need to make new connections to adapt; Sometimes it is enough to use the existing neural pathways in a different way

In longer periods, changing the strength of connections between neurons and even some structural features of neural networks can also play a role in adaptation.

However, increased activity in one part of the brain alone does not prove that new neural connections have been made. Imaging methods usually show changes in activity or properties of brain tissue, and more evidence is needed to determine the exact mechanism of the changes. For this reason, scientists differentiate between changing the function of neural networks and changing their physical structure.

The brain has the ability to change throughout life, but its flexibility is not the same at different ages. During childhood, neural networks are still developing and organizing. Sensory experiences during this period can have a profound effect on the formation of brain connections. For this reason, some growth stages are called "sensitive periods" or "critical periods".

Information is not available for a long time, even the resolution of the eye problem in later years may not lead to full recovery of visual abilities.

This is one of the reasons why the brains of congenitally blind people and people who lost their sight in adulthood may show different patterns of adaptation.

In congenital blindness, the lack of visual information from the very early stages of development affects the formation of brain networks. But a person who becomes blind in adulthood has received visual information years ago and the networks related to his vision have been formed to a large extent.

Of course, it cannot be said that the brain of one of these two groups is necessarily more flexible or efficient. What makes the difference is the time of deprivation of vision and previous sensory experiences.

For a long time, it was thought that the brain loses much of its ability to change after the end of development. According to this view, neural networks are relatively fixed in adulthood and the possibility of their reorganization is limited. More recent research has shown that this notion is not complete.

The adult brain can still reorganize its activity in response to learning, practice, and changing sensory conditions. The five-day visual deprivation experiment is one of the clear examples of this ability.

The brain's ability to adapt is not limited to childhood, and even the brain of adults can change its way of working after blindness

Studies of people who have regained some of their vision after years of severe visual impairment also show that brain networks can respond to new visual input even in adulthood. However, the plasticity of the adult brain is not the same as the plasticity of the child's brain. Some changes occur more easily during development, and some sensory abilities may be difficult to regain after years of deprivation.

For example, a person who was deprived of visual experiences for a long time as a child may still have difficulty recognizing objects or interpreting complex scenes after the eye problem is treated. This suggests that the brain's ability to change is different from its ability to fully recover lost function.

Not all changes in neural plasticity are permanent. Some of them disappear quickly with changing sensory conditions, while others may remain for a long time.

In the five-day visual deprivation experiment, the researchers observed that the change in the activity of the occipital region was quickly reversible after the blindfolds were removed. But in people who have lived with blindness for many years, brain reorganization may be more permanent.

In another study, scientists examined the brain changes of individuals with a long history of severe visual impairment before and after partial vision recovery.

Before the treatment, some areas of the back of the brain of this person were activated when hearing the sound. After the treatment and some of the visual information returned, the researchers observed that some auditory responses in these areas were reduced, but some of them remained even several months later.

This finding shows that brain changes are not necessarily unilateral and irreversible. Some networks can re-adjust to the new conditions, while some previous changes persist longer. Of course, this research was focused on one person and its results cannot be generalized to all blind people.

Neuroplasticity is usually considered a positive trait; Because it helps the brain learn new skills and adapt to changes. But not every neural change is necessarily beneficial.

For a person who has lost his vision, reorganization of brain networks can be part of the process of adaptation to new conditions. However, if in the future therapy allows visual information to be received again, the brain must once again adapt to these inputs. In such a situation, the question arises whether some previous adaptations may make the recovery of vision more difficult?

Researchers have hypothesized that some forms of neural reorganization in certain conditions can interfere with the return of the normal function of a sense. However, the available evidence is not enough for definitive conclusions and the relationship between brain adaptation and recovery of senses depends on several factors.

The important thing is that it is not possible to divide brain changes into two completely beneficial and harmful groups. A change that promotes adaptation in one situation may have a different outcome in another. Also, the activation of a brain area in processing other sensory information does not mean the permanent loss of its previous ability.