For decades, one of the most active debates of science has been to determine until when the brain continues to generate new neurons. Now, a new study presents new evidence that corroborates that neurons From the center of memory, the hippocampus, the adult age continues to form.
The investigation, led by the Karolinska Institute in Sweden and published this Thursday in the journal Science, answers a fundamental and long discussed question about the adaptability of the brain.
The director of the study, Jonas Frisén, teacher of research with stem cells at the Karolinska Institute, believes that this finding “provides an important piece of puzzle to understand how the human brain works and changes throughout life.”
The hippocampus is a region of the essential brain for learning and memory, and that participates in the regulation of emotions.
In 2013, the Frisén Research Group demonstrated in a great impact study that new neurons can be formed in the hippocampus of adult human beings.
But the scope and importance of this formation of new neurons (neurogenesis) remains the subject of debate because there is no clear evidence that the cells that precede new neurons -neural progenitor cells -really exist and are divided into adult humans.
In this new study, “We have been able to identify these origin cells, confirming that there is continuous neurons in the adult brain hippocampus”, Said Frisén.
Two new methods
To do the study, the researchers combined several advanced methods to examine the brain fabric of people between 0 and 78 years from several international biobancos.
They used a method called Single Nucleus RNA sequencing, which analyzes gene activity in the individual cell nuclei, and flow cytometry to study cell properties.
By combining this with automatic learning (Machine Learning), they were able to identify different stages of neuronal development, from stem cells to immature neurons, many of which were in the division phase.
To locate these cells, they used two techniques that show in which part of the tissue the different genes are active: RNASCOPE and XENIUM. These methods confirmed that the newly formed cells were in a specific area of the hippocampus called a dentated turn, a very important area for the formation of memory, learning and cognitive flexibility.
The results show that the parents of adult neurons are similar to those of mice, pigs and monkeys, but that there are some differences in the genes that are active.
Large variations between individuals were also observed: some adult humans had many neural progenitor cells, while others had none.
“This provides us with an important piece of puzzle to understand how the human brain works and changes throughout life,” said Frisén.
In addition, “our research can also have implications for the development of regenerative treatments that stimulate neurogenesis in neurodegenerative and psychiatric disorders,” concluded the researcher.
In statements to Efe, the senior researcher at the Severo Ochoa Español Molecular Biology Center (CBM-CSIC-UAM), María Llorens-Martín, who has not participated in this study, He explained that this work confirms that neurogenesis lasts a lifetime and does so by providing “very robust evidence and a methodology with a lot of analysis.”
And to demonstrate and shed light on the process of neurogenesis in the hippocampus of adult humans, the study has used two new techniques that have allowed identifying proliferative progenitor cells in the human hippocampus, something that not all previous studies had been able to achieve, the Spanish researcher pointed out.
The Llorens-Martín group, in fact, in 2019, showed that the human brain continued to generate new neurons up to 90 years in the teeth, although it did it with a different methodology than that of Frisén.