The neurons that persist in the brain throughout a person's lifespan are the ones that get the most activity, according to a recent US study.
The finding contradicts what scientists previously believed about the brain, that it selects certain neurons and prunes others based on something that is 'better' about them.
Carlos Lois of the Massachusetts Institute of Technology in Cambridge, Massachusetts, said scientists had previously believed that brain cells with the most accurate performance had the highest chance of being selected for long-term persistence.
He said, however, his team had discovered a survival-determining mechanism for brain cells that contradicted those beliefs.
The team's study showed, as long as brain cells are doing something, they will stay alive, even if the way they process something has errors.
The research could have far-reaching implications for new brain treatments.
Current cell-replacement brain therapies are very basic, because grafted brain cells tend not to survive the brain's own 'pruning' process.
But using the same methods as the researchers, doctors may eventually find a way to graft new brain cells onto patients.
For the purposes of the study, the researchers employed genetic technology which either enhances or dampens neural action.
The new technology is precise, and can dampen the brain activity of a single brain cell.
The research could open the way to new methods of treating degenerative neurological diseases such as Parkinson's and Alzheimer's.
The research also helps explain the mechanism behind epilepsy development in the human lifespan.
Epilepsy is a condition in which some of the brain's neurons fire randomly and uncontrollably.
Lois said that the finding seemed to show that any perturbation that increased the activity of neurons would enhance their permanence within the brain, pathologically active ones included.
This means that childhood epilepsy attacks prime the brain for epilepsy attacks later in life, because the noisy neurons that cause them are preferentially selected to survive.
