Only a generation ago had the impression that once a person reaches adulthood, the brain ceases to produce new nerve cells — that is, they do not regenerate if lost. Twenty years ago, scientists have challenged this grim prospect and have shown that the adult brain somehow can still replenish their stocks. The consequences of such would be huge: perhaps we would have won depression and Alzheimer’s disease.
But this year, however, there are several controversial works, and again sparked heated debate. Today, we still don’t know, does a fully grown new brain nerve cells.
Nerve cells regenerate?
This was a controversial report, which appeared March 7 in Nature. Contrary to several landmark discoveries that convinced the scientific community that adults can appear new nerve cells, scientists have described a complete lack of division of nerve cells, or neurons, in the adult brain tissue after death.
A month later came a second volley, when in another study, the researchers described the increasing number of newborn neurons died in the brain. This work appeared April 5 in Cell Stem Cell.
The war began when the third group of scientists did not find new neurons in the brain after death, outlining the results of their work in the July Cerebral Cortex. Many neuroscientists have joined the debate with their comments.
This war for its anti-aging ability of the brain — the latest iteration of the question which still remains unanswered. The first encouraging news about brain cells came in 1998, when scientists studied the brains of people who were treated with the compound marking of DNA in newborn neurons. The connection has appeared in the cells of the adult hippocampus, a brain structure important for learning and memory. These results, along with the 2013 study, which used other treatment method, showed that the brain can accumulate neurons throughout life.
Despite the latest negative results, many scientists are of the opinion that the new growth occurs. “Negative results were very controversial,” says neuroscientist Sandrine Tour of king’s College, London. She and her colleagues argued in the report of July 5, that recent data are not convincing enough to abandon the idea of the possibility of production of new neurons in the adult brain. “It is always very difficult to put aside the phenomenon, just not finding him”.
Part of the problem is that there are no good ways to record the birth of neurons — neurogenesis. To get an idea about this process from people, the study relied on post-mortem brain tissue, which are finicky, delicate and distinctive. Small differences in methodology or disputed identity of the cells can explain the opposite conclusions.
Despite the differences, research of this year “give impetus to the development of more sophisticated tools and models,” wrote in the June Round to comments in Trends in Molecular Medicine.
New methods of quantitative determination of active genes in individual cells may eventually provide a more accurate method of identification of newborn neurons. Other experimental methods such as lab-grown organelles of the brain or complex brain scans, can also help. If researchers can determine a proxy of neurogenesis in the form of a signal in the blood or cerebrospinal fluid, this process could be explored and the living.
If humans, like mice, can generate new neurons as adults, it would eventually protect us — or even reverse — Alzheimer’s disease and other neurodegenerative diseases.