The results of the study, funded by the National Institutes of Health, the National Science Foundation, Burroughs Wellcome Fund, the Center for Behavioral Neuroscience and the Yerkes Center, are detailed in the October issue of the journal Nature Neuroscience.

The genetically engineered virus was injected into the amygdala of the mice by Emory graduate student Kimberly Maguschak. The amygdala is a part of the brain thought to be important for forming memories of emotionally charged events.

"We found that after beta-catenin is taken out, the mice can still learn to fear the shocks," Maguschak said. "But two days later, their fear doesn't seem to be retained because they spend half as much time freezing in response to the tone."

So it appears that beta-catenin is turned on in the amygdala to help in signaling during the learning process, Maguschak said.