Until the 20th century, neurogenesis was thought to end after the development of the embryo. Starting in the second half of the last century, it was discovered that cells continue to be born in the brain throughout life. Today, this knowledge helps to understand the process of learning and memory and also how the brain is able to repair itself.
In this brief guide we are going to answer the question ‘’Can the brain heal itself?’’ We will establish at what point the brain is able to regenerate and create new cells to heal itself, what processes are involved and what are its limitations.
Can the brain heal itself?
Yes, the brain has the ability to change and heal itself, this is called neuroplasticity.
Just a few years ago it was proven that the adult human brain, under normal conditions, could generate new neurons. A team led by Peter S. Eriksson, Goteborg Sahlgrenska Hospital, and Fred. H. Gage, from the Salk Institute in California, demonstrated in 1998 the production of neurons in the hippocampus, a region related to memory and learning.
This finding indicated that stem cells, the origin of these neurons, could constitute a potential reservoir for neuronal regeneration of a damaged nervous system, opening up enormous possibilities in medicine.
The search for stem cells in other regions then began, in order to advance regenerative medicine. In the case of the nervous system, an attempt is made to repair the degenerative processes typical of many diseases; among them, Parkinson’s and Alzheimer’s.
A brief overview of the history of neurogenesis
When we suffer an injury, our skin and tissues regenerate. But the damage to the brain tends to be permanent, it has a limited regenerative capacity. This belief is what led to the idea that neurons do not regenerate for a long time. Therefore neurogenesis was limited to embryonic development.
It wasn’t until 1962 that an investigation by Joseph Altman suggested that this did occur. During the 1960s, he found neurogenesis in different areas of the brain, including the hippocampus. Further research would reveal that this part of the brain is essential for learning and memory.
The scientific community remained skeptical of the findings Altman had found in his mouse research. They did not give credibility to the methodology and tools used. Years later, already in the 80s, another investigation by Fernando Nottebohm was more conclusive.
Following the same Altman methodology, Nottebohn discovered that new cells were born in the brain of songbirds. In addition, he managed to show that these cells conducted electrical impulses, so they were neurons.
Still, it wasn’t until the 1990s that, thanks to the development of more sophisticated tools, neurogenesis came to the fore.
1990s: the emergence of neurogenesis
In the 1990s, it was shown that stem cells divided to form new cells. Also, some of them were neurons. Thanks to the development of new tools to obtain images of neurons, this theory ended up permeating the scientific community.
Another study from 1996 showed how the birth of new cells in the brain decreased as mice aged. But it never completely disappeared. As early as 1998, these certainties in mice and birds were demonstrated in the human brain.
Based on these discoveries, other research showed that the neurogenesis process did not depend only on age, but also on other factors such as experience and environment. For example, stress decreased neurogenesis, while exercise increased it.
In addition, they also observed that over a period of several months, the new cells grew into mature neurons, forming connections and firing electrical impulses.
Neurogenesis was a fact. It decreases with age, but could be improved with cognitive enrichment and exercise. In the next decade, research focused on the implications for aging and cognitive health.
Neurogenesis and aging
Until now, research has not found the relationship between neurogenesis and cognition. Therefore, the question that remained to be resolved was whether neurogenesis could benefit the aging brain.
In 2005, a study carried out with old mice showed that exercise stimulated neurogenesis, comparing them with those that did not perform.
The contribution of 2009 was significant, since it was discovered that the brain needs neurogenesis in adulthood. In this study, mice that had this ability blocked had their ability to remember similar places in a maze impaired.
In 2013, it was documented that newborn neurons contribute significantly to brain function. In addition, it began to be suggested that improving neurogenesis can prevent cognitive decline.
The benefits of exercise go beyond cardiovascular health. In addition, they preserve cognitive functions and mitigate brain atrophy in aging. These neuroprotective effects of exercise can be reflected in neurogenesis.
With new tools and technologies, current research is looking to link neurogenesis and brain aging. The objectives focus on being able to identify strategies to prevent cognitive decline.
Brain self-repair process
From analyzes of the human brain and studies of model organisms such as rodents and birds, we know that neurogenesis in the adult persists throughout the life of the organism and is essential for maintaining brain structure and function.
In the adult mammalian brain, new neurons are generated from self-renewing stem cells that are located mainly in the subventricular zone of the lateral ventricles and in the subgranular zone of the dentate gyrus of the hippocampus.
Neural stem cells located in neurogenic regions can divide asymmetrically generating a daughter stem cell and a transit amplifying cell (a type of cell that expands the pool of neural progenitors as needed).
Transit-amplifying cells differentiate into neuroblasts, which travel out of the neurogenic niche to the olfactory bulb or granule cell layer of the hippocampus. Besides being neural progenitors, neural stem cells also grow a small number of glial cells (astrocytes and oligodendrocytes).
It is interesting to see how neural stem cells share many characteristics with astrocytes in the brain, including morphology and molecular signature. In the context of an acute brain injury, astrocytes have acquired neurogenic capacities similar to those of stem cells.
Both types of cells extend their processes to make contact with the veins of the brain (another important component of the neurogenic niche that provides a torrent of nutrients and growth factors that help regulate the neurogenic process).
The subventricular zone is separated from the lateral ventricles and filled with cerebrospinal fluid (CSF) or cerebrospinal fluid by a layer of ependymal cells.
This border is partially permeable by stem cells, which interpose themselves between the ependymal cells to establish contact with the cerebrospenial fluid.
This complexity of the neurogenic niche would be one of the reasons why neural stem cells and neural production only persist in certain areas of the brain.
Aside from the subventricular zone and the subgranular zone, there is a third area of neurogenic activity, the post-brain striatum (striatum), which has recently been identified and appears to be specific to the human brain.
The neurogenesis of the striatum has also been observed in mice but only after some brain injury such as a stroke
In humans, neuronal production in the striatum appears to be part of normal brain homeostasis, and the process is specifically disrupted in patients with Huntington’s disease (a hereditary genetic condition that results in progressive neurodegeneration).
Whether the striatum contains only neural stem cells or other types of cells with neurogenic abilities is not yet clear.
Similar to the brain, most adult tissues contain this rare and slowly proliferating type of stem cell. In self-renewing tissues like the adult brain and skin, progenitor cells are constantly being produced, while other tissues stem cells only activate in response to disease or injury.
Normally, activation of stem cells that is triggered by injury initiates tissue repair or minimizes damage. In some cases, the local stem cells that are mobilized in response to injury can be corrupted from the healing process to tumor formation, as occurs in some cases of skin cancer.
Understanding the molecular mechanisms that govern the specific functions of stem cells can help scientists influence the outcome of the adult stem cell response to disease and injury to promote healing and regeneration.
Can your brain repair itself?
After this detailed and technical introduction, this is the TED Lesson where, from the hand of Ralista Petrova, in an entertaining and lively way we can learn the entire process of brain self-repair
The Brain Could Repair Itself, With Help
Neurosurgeon Jocelyne Bloch knows about the brain’s failure to heal itself perfectly, from stroke care to car crash injuries. But now, she believes, in doublecortin-positive cells, she and her team have found the secret to neuronal repair.
They are stem cell-like cells, highly adaptable, which can help regenerate and reconstruct when extracted from the brain and then pumped back into an injured region of the same brain. So according to Bloch, “with a little help the brain might be able to repair itself.”
Yes, this can be a breakthrough in neuroscience. Let’s hope little by little to understand more about this wonderful organ: the human brain.
FAQS: Can the brain heal itself?
Can a damaged brain heal itself?
It sometimes occurs that the brain can regenerate itself after a brain injury, constructing new brain cells to replace damaged ones. The repair, however does not take place fast enough to enable recovery from degenerative diseases.
How long does the brain take to heal?
Recovering from a brain injury takes time. Most people feel better in 3 to 6 months.
What helps the brain heal?
How to make the brain recover after injury:
- Get plenty of nighttime sleep and rest throughout the day.
- Slowly increase your operation.
- Write down the things for you to note that could be more complicated than normal.
- Stop smoking, caffeine, and medications.
- Eat brain-sanitary foods.
- Keep hydrated by providing plenty of water to drink.
How can I rebuild my brain cells?
5 habits that promote the creation of neurons
- Aerobic exercise
- Stress and anxiety under control.
- Always active mind.
What happens when left brain is damaged?
The left cerebral hemisphere controls the movements of the right side of the body. Depending on its severity, a stroke that affects the left cerebral hemisphere can cause functional loss or affect motor skills on the right side of the body and also loss of speech.
In this brief guide we answered the question ‘’Can the brain heal itself?’’ We have established at what point the brain is able to regenerate and create new cells to heal itself, what processes are involved and what are its limitations.
If you have any questions or comments please let us know!
When damaged, the adult brain repairs itself by going back to the beginning. (2020). Retrieved December 3, 2020, from ScienceDaily website: https://www.sciencedaily.com/releases/2020/04/200415133654.htm
Neuroplasticity: how the brain can heal itself. (2015, April 21). ABC News. Retrieved from https://www.abc.net.au/radionational/programs/allinthemind/neuroplasticity-and-how-the-brain-can-heal-itself/6406736#:~:text=Scientists%20now%20know%20that%20the,our%20understanding%20of%20the%20brain.
van Praag, H. (2005). Exercise Enhances Learning and Hippocampal Neurogenesis in Aged Mice. Journal of Neuroscience, 25(38), 8680–8685. https://doi.org/10.1523/jneurosci.1731-05.2005