WASHINGTON – The act of exploring helps shape the brain, and adventuring is what makes each individual different, according to a study by researchers in Germany.
The findings, published in the U.S. journal Science, may offer new paths to treating psychiatric diseases.
Researchers sought to pin down why identical twins are not perfect replicas of each other, even when they have been raised in the same environment.
They studied the matter using 40 genetically identical mice. The mice were kept in an elaborate, five-level cage connected by glass chutes and filled with toys, scaffolds, wooden flowerpots, nesting places and more. The space available to explore spanned about 5 sq. meters.
“This environment was so rich that each mouse gathered its own individual experiences in it,” said principal investigator Gerd Kempermann of the German Center for Neurodegenerative Diseases.
Even though the mice were genetically the same, and the environment they were kept in was also the same, they showed individually different levels of activity. Some explored a lot, some did not. And by fitting them with a special microchip that emitted electromagnetic signals, scientists could track how much the mice moved around and quantify their exploratory behavior.
“Over time, the animals therefore increasingly differed in their realm of experience and behavior,” said Kempermann.
Over the course of three months, the mice developed very different personalities.
Researchers found that the brains of the most explorative mice were building more new neurons — a process known as neurogenesis — in the hippocampus, the center for learning and memory, than the animals that were more passive.
Control mice kept in a less enriching environment showed less brain growth.
Kempermann and colleagues said they have shown for the first time how personal experiences and ensuing behavior contribute to individualization, and that neither genetics nor environment alone could cause this personal growth.