Can the hippocampus be repaired?

In this post we are going to answer the question ‘’Can the hippocampus be repaired?’’  We will discover if this area of the brain responsible for memory and memories can be repaired in adults through neurogenesis.

Can the hippocampus be repaired?

Yes, the hippocampus can be repaired. It has been observed that antidepressants promote the development of new brain cells (neurogenesis) and eventually repair the hippocampal structure in depressed individuals.

It has been believed for many years that the human brain is an organ that evolves during the first months of development and that it stops evolving after reaching maturity. This brain definition leaves the door open to assume that the only possible improvements in our nervous system arise by the death of neurons.

Obviously, when a portion of the neocortex is removed, the brain of a human improves, just like it is not quite the same after having undergone a minor stroke.

The human brain produces new neurons up to the age of 80 in the hippocampus, a region involved in learning. However, the ability to generate new cells in this area decreases dramatically in people with Alzheimer’s.

This is what concludes an investigation published in the journal Nature Medicine. In addition to settling a controversy of more than two decades, the finding opens a possible way to new therapeutic strategies against Alzheimer’s.

During embryonic development, the human body is a tide of cells that multiply and migrate endlessly to make up every single tissue, including the brain.

But, shortly after birth, the generation of new neurons (neurogenesis) stops: a good part of the nerve cells that we have accompanied us from birth to death. In most mammals, however, neurogenesis continues into adulthood in two areas of the brain: the striatum and the hippocampus.

Neurogenesis in the hippocampus of the adult human brain

Now, a team of researchers has analyzed samples of thirteen healthy people between the ages of 43 and 87 who had donated their brains for research and have detected neurogenesis in the hippocampus in all of them.

Although the production of new neurons decreases slightly with age, the results show it is maintained throughout life.

Researchers have also found that the way to treat brain samples is key to being able to observe the new neurons of the hippocampus in the process of maturing.

Depending on how the tissue is treated, cells can be altered and lose the signals that make them visible under the microscope. That explains why until now some studies have detected them and others have not.

In mice, the new neurons generated in the hippocampus are involved in discrimination between similar stimuli and in social learning

“For now we do not know what functions these new hippocampal neurons have in humans. We know that in rodents and other mammalian species they participate in hippocampal-dependent learning. They provide plasticity to the entire circuit”, declare the researchers. “They are involved in discrimination between similar stimuli and in social learning.”

His team has also analyzed samples from 45 Alzheimer’s patients and discovered that, in this disease, the neurogenesis of the hippocampus is stopped short. “It is not known why. For us it has been very surprising.

There is a very significant reduction in immature neurons very early in the disease, even before we can detect massive degeneration”, they point out. “In the future, it would be really interesting to be able to detect the number of new neurons in a non-invasive way, during people’s lives, to monitor the progress of the disease.”

The finding also suggests that, in the future, neurogenesis in the hippocampus could be a possible therapeutic target against Alzheimer’s.

“Non-pharmacological drugs and interventions are being investigated that enhance it in animals,” says one of the authors. “For example, putting mice to do physical exercise or keeping them in an environment of social stimulation has a very positive impact”

“But there is still a lot to do,” he points out. “First it will be necessary to demonstrate whether these neurons are important in the human brain and, once demonstrated, try to counteract this loss that occurs both in physiological and pathological aging.”

They discover the source of new neurons in the brain hippocampus

Researchers at the Perelman School of Medicine at the University of Pennsylvania, in the United States, have shown in mice that a type of stem cells, located in the hippocampus, are the producers of new neurons throughout life.

The hippocampus is one of the main structures of the human brain and other mammals, involved in learning and memory. Therefore, this finding may help neuroscientists to discover how to maintain the conditions to preserve these qualities as in a young brain, and to repair and regenerate damaged or aged parts of the brain.

Creation of new neurons throughout life

In recent decades, neuroscientists have rejected the ancient belief that mammals are born with the full supply of neurons that will accompany us throughout life. The latest studies show that, in at least two regions of the brain (the centers of the sense of smell and the hippocampus), new neurons grow throughout life.

“We have shown, for the first time in mammals, that neurons in the dentate gyrus of the hippocampus [serrated band of gray matter] grow and develop from a single population of stem cells, over a lifetime,” explains Dr. and Neuroscience professor Hongjun Song in a statement.

“New immature neurons are more flexible to make connections in the hippocampus compared to mature neurons, which is critical for healthy learning, memory and mood regulation,” Song adds.

The researchers showed that the neural stem cells they found had a common molecular signature throughout the lifespan of the mice. Molecular signatures are sets of genes, proteins, and other variables that can be used as markers for a particular trait determined by genetics. In this case, the expression of the HOPX gene was studied.

To demonstrate this, the researchers tagged neural stem cells in embryos while the brain was still developing, and tracked the mice from birth to adulthood. This approach revealed that the new neural stem cells branded with their precursors made neurons continuously throughout the life of each animal.

Brain plasticity

“This process is unique to the brain,” says Dr. Guo-li Ming, also a professor of neuroscience. “In the hippocampus, these cells never stop replicating and contribute to the flexibility of the brain in mammals.”

This ability is called plasticity and, thanks to it, the brain can establish new connections throughout life to compensate for injuries and illnesses and to adapt in response to new contributions from the environment.

Future of research

The next goals will focus on looking for the same neural stem cells in humans, starting the search in post-mortem brain tissue and investigating how this population of cells is regulated.

The new findings could be important for the fight against neurodegenerative diseases like Alzheimer’s. In this disease, the hippocampus is one of the first regions of the brain to be damaged.

We are capable of creating new neurons at any age with a simple exercise (which is in your hands)

We are capable of creating new neurons, even as adults. This finding is relatively new, because it was thought that it was born with a certain “bank of neurons” that was diminishing with the passage of time, but that it was not possible to renew or expand. However, the latest findings in neuroscience disprove this belief.

The brain is plastic: it is possible to create different connections and even in some areas, such as the hippocampus, new neurons can be born, according to Professor Terry Sejnowski, from The Salk Institute for Biological Studies. There is room for maneuver regardless of age.

The hippocampus is shaped like a seahorse and is one of those responsible for our memory and our spatial capacity. Research on this area of ​​the brain began with rats shown various images that they had to learn to differentiate.

When the rodents succeeded, it was observed that new neurons had been generated in their hippocampus.

But if the animal stopped exercising, the young neurons disappeared. If he resumed the activity, they would reappear, that is: repeated practice helps to generate new neurons in the hippocampus.

In the case of humans, if we had to decide what activity really allows us to keep the brain young, Sejnowski does not doubt it. Sport is the best anti-aging treatment for gray mass.

It was known that playing sports is a way to take care of the body and reduce stress thanks to the hormonal dances that are activated by dopamine, serotonin and norepinephrine.

But more recent research shows that physical exercise also improves the secretion of brain neurotrophic factor (which positively influences memory and a more positive mood) and allows new neurons to be born in our hippocampus.

Despite its advantages, there does not seem to be much awareness of the link between learning and sport. But educating children and adults in sports not only helps to maintain body health, but also to keep the brain younger and with the capacity to generate neurons. As Sejnowski sums up, “The gym and recess are the most important parts of the curriculum.”

Experts suggest that it is costly to exercise three times a week with a minimum duration of 30 minutes. It is therefore worth finding a friendly exercise, a group of friends and putting on your running shoes. The hippocampus will appreciate it.

FAQS: Can the hippocampus be repaired?

Can the hippocampus heal?

Since then, throughout the adult human hippocampus, many experiments have found signals of new neurons, causing several scholars to accept that this portion of the brain could even regenerate itself in people over existence.

What happens if the hippocampus is damaged?

Damage to the hippocampus can also come from oxygen deprivation (hypoxia), inflammation of the brain (encephalitis), or temporal lobe epilepsy. People who have suffered extensive damage to the hippocampus may experience an inability to acquire or retain new memories (amnesia).

Can you live without a hippocampus?

In short, both the recording and the storing of memories are orchestrated by the hippocampus, and this “memory consolidation” does not happen without it. Since his memory died, H.M. He lost his career and had no other alternative but to choose to live with his parents.

Can the brain be repaired?

Repairing a damaged brain involves replacing dead neurons with new ones, but not through cell division as occurs in other organs such as the liver. Neural stem cells are needed. … Despite what was believed only a few decades ago, the adult brain regenerates.

How do I strengthen my hippocampus?

Exercise

Another way to strengthen your brain is by stimulating the hippocampus, which is the area in charge of forming memories. For this, you must constantly perform physical activity, as this increases the number of capillaries in the region. New cells are also created.

In this post we answered the question ‘’Can the hippocampus be repaired?’’  We discovered if this area of the brain responsible for memory and memories can be repaired in adults through neurogenesis.

If you have any questions or comments please let us know!

References

Hanson, Nicola D.; Owens, Michael J.; Nemeroff, Charles B. «Depression, Antidepressants, and Neurogenesis: A Critical Reappraisal». Neuropsychopharmacology 

Rakic, P.. «Evolution of the neocortex: a perspective from developmental biology.». Nature reviews. Neuroscience.

A Common Embryonic Origin of Stem Cells Drives Developmental and Adult Neurogenesis. D. A. Berg et al. Cell, 28 March 2019. DOI:https://doi.org/10.1016/j.cell.2019.02.010.