'Smart' mice

From UT Southwestern Medical Center.

Mice genetically engineered to lack a single enzyme in their brains are more adept at learning than their normal cousins, and are quicker to figure out that their environment has changed, a team led by researchers at UT Southwestern Medical Center has found. …

“It’s pretty rare that you make mice ‘smarter,’ so there are a lot of cognitive implications,” said Dr. James Bibb, assistant professor of psychiatry and the study’s senior author.

“Everything is more meaningful to these mice,” he said. “The increase in sensitivity to their surroundings seems to have made them smarter.”

The engineered mice were more adept at learning to navigate a water maze and remembering that being in a certain box involves a mild shock. Equally important, Dr. Bibb said, when a situtation changed, such as the water maze being rearranged, the engineered mice were much faster to realize that things were different and work out the new route.

Dr. Bibb cautioned that while the mice learn faster, studies on the long-term effects of deleting the enzyme, called Cdk5, from the brain are continuing. …

Normally, Cdk5 works with another enzyme to break up a molecule called NR2B, which is found in nerve-cell membranes and stimulates the cell to fire when a nerve-cell-signaling molecule, or neurotransmitter, binds to it. NR2B previously has been implicated in the early stages of learning.

The new research showed that when Cdk5 is removed from the brain, the levels of NR2B significantly increase, and the mice are primed to learn, Dr. Bibb said.