How Can Neurons Change Over Time And How Do We Know This

Abstract

Yous might not wait it, but the encephalon is always irresolute—it adapts itself to good and bad life experiences. We phone call this neuroplasticity. Although neuroplasticity ordinarily helps u.s. cope with bug, sometimes things get wrong, and the changes produced by neuroplasticity are harmful to the person. In this article, we embrace 2 cases of neuroplasticity, one positive and one harmful. The positive one is near changes that happen when we are immature and have good social experiences. The harmful one is about phantom limb syndrome, a foreign phenomenon felt by amputees in their limbs and organs … that no longer exist!

What is Neuroplasticity?

We have all heard sentences, such equally "The encephalon is a complex structure!" or "The brain commands all body functions!" but what fewer of us know is that the brain is not sitting there unchanging inside our skulls. It is always adapting to all sorts of different things and situations. Afterward y'all finish reading this article, we guarantee that your encephalon will be different!

The brain changes itself through a process called neuroplasticity . Allow u.s.a. decode this give-and-take. Neuroplasticity is a combination of two terms: neuro and plasticity. When we are talking about something related to the encephalon, we use the prefix neuro. The second term, plasticity, refers to the fact that the brain is always transforming itself. When you encounter someone or learn a new fact, your encephalon changes its structure and function. The environs tin modify our brains, fifty-fifty if we are not aware of information technology. Some events change the way encephalon cells communicate with i another, by strengthening or weakening this communication. Other events will shape how the brain interprets things. All these changes end up modifying our behaviors!

Before moving on to the examples, nosotros must consider 2 issues. Starting time, neuroplasticity changes with age. As nosotros grow older, the brain continues to notice different ways of dealing with new things and situations [ane, two]. The ability to do this is related to the health of the brain. Why are older people who have ever exercised and read a lot of engaging books less forgetful of things? Because an agile, healthy brain can shop mental resources that can be used, when it gets older, to modify itself. The second effect we must consider is that some neuroplastic events may non be helpful to us and may even be extremely harmful! This is what we call maladaptive plasticity [iii].

Social Experiences and Neuroplasticity

So, nosotros know that nosotros must always effort to exercise engaging activities to enhance the encephalon's abilities, and that this will be very important if we want to maintain healthy brains as nosotros become older. But are there any benefits of neuroplasticity for a younger encephalon? The answer is a definite YES! Scientists have found that there are certain time frames in our lives during which learning and brain development are strengthened. This is true for various systems, such equally the visual organization, and even for more complex ones, such every bit the social noesis arrangement , which is the grouping of brain regions that helps u.s.a. sympathise social data. Nosotros telephone call these moments of heightened plasticity critical periods .

There are disquisitional periods for neuroplasticity, too. Equally our first example, we will run into how the environment influences social learning in a critical period during adolescence. Offset, let us dive for a moment into the brain's microscopical construction.

The brain is made up of many nervus cells, called neurons . In well-nigh every region of the brain, the neurons undergo myelination , which involves the envelopment of neurons by a fatty (rich in lipids) membrane called myelin. Myelination greatly increases the efficiency of the brain'due south work. Nonetheless, the critical period for myelination of neurons differs among brain regions. The part of the brain that helps us make sense of emotions, retention, and social information, called the medial prefrontal cortex (mPFC), is ane of the last regions to myelinate. Myelination of the mPFC takes place during boyhood.

Adolescence is a difficult catamenia in the evolution of our social abilities because it is the time when we start interacting more closely with friends and adults. Our brains must deal with a huge amount of social information during this flow, equally we ask questions like, "Who is my crush?" or "How should I talk to him/her and inquire him/her out?" To navigate these situations, the brain'due south neurons must talk amongst themselves in complex neural circuits, to help a person navigate the social world. Everything needs to be working if we await to manage these situations appropriately.

The problem is that we are not born fix for such interactions. Although the brain cells and the circuits are all there, we first need to improve these circuits and optimize their operation.

Not so long ago, scientists discovered that, during adolescence, something triggers the myelination of neurons in the mPFC, and this helps united states to better bargain with social situations. Interesting fact: the event that triggers this process of myelination is social interaction! To make this articulate: if you lot want to be proficient at social interaction, you must first interact! This is one of those cases where "do makes perfection." Contempo bear witness shows that, between the ages of 15–20, the brain is at its peak potential to transform itself [4]. Remember the critical catamenia? We know that if we exercise non engage in social experiences during our adolescence, the circuits in the mPFC volition not myelinate, and this will affect our entire lives, mail-adolescence.

Researchers have shown that if a juvenile mouse is deprived of social contact, information technology will avoid interacting with other mice [v]. Social experience during this critical flow is and then important that, even if the isolated animal is later housed with other mice, it will not regain its normal beliefs. So, once the window closes, if at that place was a lack of appropriate social experiences, social behavior is forever changed.

A Tale of Phantoms and Maladaptive Plasticity

Wars and diseases can crusade many terrible consequences, including the amputation of a limb. Amputation is a sad condition, merely it can be also chilling. Some people who have had limbs amputated have the physical awareness that the amputated function still exists. This ghostly experience is part of a condition called phantom limb syndrome , which consists of feeling pain, movement, and other sensations coming from an amputated limb [half-dozen]. Imagine how dreadful it must be!

Although phantom limb syndrome has been known since the sixteenth century, it was not until the 1990s that its symptoms were attributed to neuroplasticity—a maladaptive (a harmful) form of it.

At that place is 1 portion of the encephalon, called the somatosensory cortex (SSC), that is responsible for interpreting the world through the sense of touch. "Is the surface shine?" and "Is the flooring cold?" are questions that are answered by the SSC. The SSC is too responsible for something called proprioception. Before we explicate what this word means, practice the following experiment: close your eyes and effort to touch the tip of your nose with the tip of your index finger. Did you do it? If so, you should be amazed past your superpower: you could do it without seeing the move! This is proprioception—we know the position of our bodies and their parts, fifty-fifty with our eyes closed.

So, what happens when one loses a limb past amputation? Does the region inside the SSC responsible for that limb stop working? Usually, the brain area only slows downwards its office, simply sometimes things go wrong, and the brain area responsible for the missing limb becomes hyperactive. How can it exist hyperactive if the limb is missing?

In cases of leg amputation, neuroplasticity allows the neighboring areas in the SSC, such as the ane in charge of the thigh, to take control of the missing leg surface area. One possible explanation is that active neurons in the thigh area "find" that a neighboring leg region is inactive and extend some of their fibers to connect to the inactive neurons. Effigy one is an example of research conducted in our laboratory with amputees. We constitute that not only the representation areas of the intact and missing limbs were altered, but also that the myelination of some parts of the brain was reduced.

• Effigy one - Neuroplasticity in a left leg amputee.
• The daughter who lost her left leg was gently stimulated with a brush in iii places: (1) the stump; (2) the same region of the intact leg; and (3) the remaining foot. The colored spots on the brain images point which regions were most active when the brush touched her peel. In (1), you can meet that the stimulation of the stump produces a larger expanse of activation than when the brush touches the thigh of the intact leg (ii). In addition, stimulation of the stump seems to actuate similar regions every bit when the foot is stimulated (3), only the areas are smaller. Notice that the left parts of the body are represented in the right side of the encephalon, and vice-versa. S1, Somatosensory Expanse; M1, Motor Area; and M2, Supplementary Motor Area. Analogy past Julio Xerfan.

Okay, and then neurons from the thigh move toward and connect to neurons in the missing-leg area—how can this neuroplasticity translate into a phantom sensation? Imagine that you tin can experience each fold of your clothes that touches your limbs, but even when you wear a bathing suit, yous can still feel that your limbs are there, just past moving them. This means that the limb surface area in your brain is constantly being activated. But in the case of amputation, when the neurons from the thigh and the lower leg go connected, both are activated when there is something stimulating the thigh peel. Thus, a affect to the thigh triggers a sensation of affect in the missing leg. The proprioceptive sensation in the thigh caused past moving may too trigger a proprioceptive sensation in the missing leg.

In other words, the brain (or at least the SSC) misunderstands the sensory experience, believing that the missing limb is still in that location.

Conclusion

We take discussed two cases of neuroplasticity: one good and 1 harmful. Nosotros learned that, early in our lives, at that place are fourth dimension windows during which neuroplasticity and development of some encephalon regions are very of import. Such is the case for myelination of the mPFC, which is greatly dependent on our social experiences. As an instance of harmful neuroplasticity, nosotros learned that, in the event of an amputation, the encephalon might not realize that the limb is gone. This ways that the parts of the brain that were responsible for interpreting signals coming from that limb (for example, the awareness of touch) will remain active, leading to phantom limb syndrome. Overall, from these two examples, you lot tin meet that the encephalon is not static, it is constantly responding to challenges. Every piece of information we learn or every person nosotros meet can atomic number 82 to lasting furnishings in our brain and our lives.

Glossary

Neuroplasticity: ↑ Brain'due south ability to change its structure and function in response to life'southward events.

Maladaptive Plasticity: ↑ A harmful form of plasticity, such as the one that occurs in the phantom limb syndrome.

Social Knowledge Arrangement: ↑ Set of skills and brain regions that are responsible for both understanding social rules and guiding our social behavior.

Critical Period: ↑ Time frame where the evolution of some regions of the brain and learning are enhanced.

Neuron [nur-aan]: ↑ One of the many cell types making upwards the encephalon. Neurons connect to one some other forming circuits, like to train tracks. This is how information travels in the brain.

Myelination [mai-uh-luh-nei-shn]: ↑ A process in which parts of the neuron are covered by membranes of a substance called myelin. Myelin functions like the rubber cover of electric wires, and it increases the speed past which information goes from one neuron to another.

Phantom Limb Syndrome: ↑ Condition where an amputee however feels sensations from the missing limb or organ. Although not always, it tin can exist a painful sensation.

Disharmonize of Interest

The authors declare that the inquiry was conducted in the absenteeism of any commercial or fiscal relationships that could be construed equally a potential conflict of interest.

Acknowledgments

We thank for the real human brain images of the effigy, provided past our colleague Theo Marins.

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References

[one] ↑ Goh, J. O., and Park, D. C. 2009. Neuroplasticity and cognitive aging: the scaffolding theory of aging and noesis. Restor. Neurol. Neurosci. 27:391–403. doi: ten.3233/RNN-2009-0493

[two] ↑ Gutchess, A. 2014. Plasticity of the aging brain: new directions in cerebral neuroscience. Science 346:579–82. doi: 10.1126/science.1254604

[iii] ↑ Brown, A., and Weaver, L. C. 2012. The nighttime side of neuroplasticity. Exp. Neurol. 235:133–41. doi: 10.1016/j.expneurol.2011.11.004

[four] ↑ Fuhrmann, D., Knoll, L. J., and Blakemore, S. J. 2015. Adolescence equally a sensitive menstruation of brain development. Trends Cogn. Sci. 19:558–66. doi: 10.1016/j.tics.2015.07.008

[5] ↑ Makinodan, M., Rosen, K. M., Ito, S., and Corfas, 1000. 2012. A critical period for social experience-dependent oligodendrocyte maturation and myelination. Science 337:1357–threescore. doi: 10.1126/scientific discipline.1220845

[vi] ↑ Simões, E. L., Bramati, I., Rodrigues, Due east., Franzoi, A., Moll, J., Lent, R., et al. 2012. Functional expansion of sensorimotor representation and structural reorganization of callosal connections in lower limb amputees. J. Neurosci. 32:3211–xx. doi: 10.1523/JNEUROSCI.4592-xi.2012

Source: https://kids.frontiersin.org/articles/10.3389/frym.2020.522413

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