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Scientists’ Shocking Claims Put the Debate of Brain GROWTH to Rest

There have been a number of researches in the past which have stated that brain growth is not possible in adulthood – however, this fact has always seem to be a bit weird to all of us. How is it possible for the brain to not grow after a certain age? And what about the studies which claim that doing certain exercises or eating specific foods can change the brain structure and neural pathway even in adulthood? It turns out that the claim made by the father of modern neuroscience, Santiago Ramón y Cajal that the adult brain never makes new neurons still holds true.

Neurogenesis: Truth or Myth?

For many years, scientists were convinced that neurogenesis, the process through which new neurons are created, is only possible during the growth of the embryo and infanthood. But as time went by and more studies began to surface on the issue, scientists weren’t so sure if what they already knew about neurogenesis was actually true.

In the 80’s, researchers began challenging Santiago Ramón y Cajal’s claims that neurogenesis doesn’t occur in adults by showing evidence that certain activities can result in the formation of new neurons even in later stages of life.

According to the concept of adult neurogenesis, diet and physical activity can generate new brain cells in an important area of the brain called hippocampus, associated with learning and memory

Researcher Finds no Signs of Neurogenesis in Adults

The idea of neurogenesis is popularly-accepted and many exercises and ‘brain foods’ are advertised to grow brain cells – but the truth is, the production of fresh neurons in adulthood may not be possible after all. A recent study conducted in University of California drew a shocking conclusion that the brain does not experience any growth in adulthood no matter what the circumstances.

Alvarez-Buylla, the lead author of the study explained that through observing the brains of a large body of participants with different lifestyles, he is now convinced that adult neurogenesis is just a myth and may only occur in rare circumstances.

Alvarez-Buylla says that the process of neurogenesis isn’t as simple as most people had previously assumed; you can’t just start exercising out of the blue and expect the number of brain cells to grow. Mental health expert Heather Cameron argues that the age-old debate about adult neurogenesis continues to exist due to the difficulty in identifying young brain cells in some species.

Neurogenesis May Occur in Nonhuman Mammals

Experiments on rats have shown that adult neurogenesis is possible in hippocampal regions of inhuman animals, but very little evidence of the process exists on humans.

Alvarez-Buylla, through comparing brain scans of rats and humans,  discovered that the continuous production of neurons in the olfactory bulb, a brain region responsible for smell, occurred only in rats and not in humans. A similar observation was made in the frontal lobe of the two mammals, an important part of the brain responsible for critical thinking and performing various other tasks. The researcher says that even though there is plenty of evidence of new neurons being formed in infants, the same cannot be said about adult humans.

Alvarez-Buylla was more interested in the region of the brain which has become a central focus for most neurogenesis-related researches: hippocampus. He studied the brains of more than a dozen deceased adults who had donated their bodies to scientific research. The researchers searched for any signs of telltale molecules, which are considered the markers for young neurons, in the hippocampal regions of the brain but found absolutely nothing. However, the observations from much younger brains showed traces of the telltale molecules, proving that neurogenesis does occur – but only in young brains.

Previous research has shown that humans aren’t quite as similar to other closely-related mammals. For example, the neural stem cells in a monkey’s hippocampus are beautifully laced together to form a ribbon-like pattern which is responsible for the production of new brain cells; however, this pattern is not present in human brains.

Critics of the study say that it is important to know the state of the participants before they died since certain factors like stress and physical activity can greatly affect neurogenesis in adulthood. Alvarez-Buylla agrees that more work needs to be done to determine whether brain cells are produced after infanthood; but for now, the important question remains: if our brains don’t really develop in adulthood, how do we learn new things?

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