Early experience rather than genes forges an individual’s personality, new research suggests.

As any mother with identical twins knows, siblings who share the same genes can become very different people.

The reason may lie in the subtle interplay between experience and brain development.

Scientists conducted experiments with identical twin mice raised in the same stimulating environment filled with toys and other rodents.

Differences in the way each mouse experienced its surroundings led to changes in brain structure which became magnified over time.

The more their brains developed differently, the more this in turn affected their behaviour, triggering further brain changes.

As a result over a period of three months, the mice displayed highly individual behaviour patterns.

Study leader Professor Gerd Kempermann, from the German Centre for Neurodegenerative Diseases in Dresden, said the animals were not only genetically identical, they were also living in the same environment.

“However, this environment was so rich that each mouse gathered its own individual experiences in it. Over time, the animals therefore increasingly differed in their realm of experience and behaviour,” Prof Kempermann said.

The differences were linked to the creation of new neurons in the hippocampus, a region of the brain important for learning and memory.

Similar nerve cell formation in the hippocampus occurs in the brains of human children.

“Hence we assume that we have tracked down a neurobiological foundation for individuality that also applies to humans,” Prof Kempermann added.

The findings are published today in the journal Science.

Prof Kempermann’s team observed 40 genetically identical mice kept in an enclosure offering them a lot of scope for activity and exploration.

Each mouse was tagged with a microchip radio transmitter that allowed the scientists to track its movement and behaviour.

Co-author Professor Ulman Lindenberger, from the Max Planck Institute for Human Development in Berlin, said their findings showed that development itself contributes to differences in adult behaviour.

“This is what many have assumed, but now there is direct neurobiological evidence in support of this claim. Our results suggest that experience influences the ageing of the human mind,” he said.

Animals housed in an unattractive, unstimulating enclosure showed reduced levels of hippocampal nerve generation, the researchers found.

“When viewed from educational and psychological perspectives, the results of our experiment suggest that an enriched environment fosters the development of individuality,” said Prof Lindenberger.


Source: Ninemsn – http://goo.gl/LVnkV