Mom's childhood experience affects offspring's memory: study
When young mice are raised in a memory-enhancing environment and then grow up to have their own offspring, those offspring also have better memories into adolescence, a new study has found.
"I didn't believe it at first," said Larry Feig, the biochemistry professor at Boston's Tufts University School of Medicine who led the study. "Classical Mendelian genetics doesn't work that way."
But the experiment was repeated with the same results — even when the offspring were raised by a surrogate mother who wasn't exposed to the enriched environment — before being published in the Feb. 4 issue of the Journal of Neuroscience.
The study came about after Feig's research group conducted a previous study that found mice bred to have memory problems overcame their problems if they spent two weeks in an enriched environment with toys, plastic tubes and cardboard boxes while they were young.
Shaomin Li, a postdoctoral fellow in Feig's lab, suggested that the offspring of such mice be tested too.
The memory tests involved placing the mice in a box, where they received a "mild little shock to the foot" at a certain location. If the mice remembered where that was, they would freeze up the next time they reached that spot.
In fact, the offspring of the mothers who had been exposed to the enriched environment long before their pregnancies remembered better than the offspring of mothers who had been raised in an ordinary lab cage.
Effect lasted just 1 generation
The inherited memory enhancements among the offspring faded away when the mice reached adulthood, Feig said. It also was not passed on to the grandchildren who had been exposed to the enriched cage.
Similar results were found among normal mice who did not have a genetic memory problem.
The researchers suggested that the enhanced memory and its inheritance was the result of cellular changes to long-term potentiation — a measure of how well two nerve cells communicate. That can be measured by electrically stimulating two nerve cells in a brain slice removed after the mouse has died and recording the response.
More long-term potentiation is associated with better memory. The results of the long-term potentiation tests were similar to the results of the memory tests on the live mice.
Feig said it is hard to say whether similar patterns of memory inheritance would be seen among people.
But Dean Hartley, the neuroscience researcher at Rush University Medical Center who co-authored the paper and conducted the long-term potentiation tests in his lab, said he wouldn't be surprised if the same mechanism works in humans.
There are some human studies that already suggest that parents' environment long before pregnancy can affect their offspring, he said.
However, he said, given that an enriched environment before pregnancy can have a positive effect on one's offspring, it's also possible that a poor environment could have a negative affect.
"It wouldn't be surprising to find it can go both ways."