Researchers have found that wisdom in old age depends on a fresh supply of new brain cells.
Canadian researchers found that when mature mice learn a new task, their newly generated brain cells are three times more active than their old ones, the New Scientist reported on its website.
A team of researchers led by Paul Frankland at the Hospital for Sick Children in Toronto, Canada, injected a group of mice with a chemical agent that stains only those cells born in the animals' brains at the time of injection, the report said.
The team taught some of the mice a week later to navigate through a maze, before analysing the cells in a region of their brain called the hippocampus, which is the key to learning and memory.
In stages, the rest of the mice also underwent this paired process of learning and hippocampal examination at increasing intervals after the initial injection.
The team analysed the rodents' stained hippocampal cells for key proteins - evidence that the cells were active and forming new neural connections vital for learning - and found that the stained cells had undergone significantly more activity in the mice that had learned the maze soon after the injection, when the stained cells were newly generated.
Those that had learned the maze six weeks after the injection had three times as much "activity" in their stained cells as those mice that learned the maze eight weeks after injection, when the stained cells were fully mature, according to the researchers.
The researchers claimed the study is the first to provide positive evidence that newly generated brain cells are more active than old ones.
The findings add to a growing body of evidence that the adult brain needs a steady addition of new cells to maintain its mental faculties.