The Duke team administered anesthesia to a mouse and stimulated the release of noradrenaline with an electrode while wafting the scent of either food or the urine of another mouse under the nose.
"We wanted to see if these two elements noradrenaline and odor present at the same time were the key ingredients needed in the recipe for creation of memory this is a concept that had not been directly tested before this study," Shea says. "In essence, we recreated the chemical reaction that would occur when the mouse experiences a social event, such as giving birth," Shea says.
Researchers knew they could observe brain activity in more detail when the mouse was under anesthesia. If awake, the mouse would be forming memories from the surrounding environment. "When the animal is asleep, you can watch neurons in the brain rewire to store a memory and once awake see what the mouse learned even though it was asleep when the memory was created."
What they saw was an approximate 40 percent reduction in neuron activation after triggering the noradrenaline release suggesting that a memory of the odor had been formed.
A day later, after the mouse was awake, the team observed changes in behavior in response to the scents, showing that they remembered the smells from when they were asleep.
"This work may have implications for furthering our understanding of how long-lasting memories are formed that are important to social bonding," says Richard Mooney, Ph.D., co-author and associate professor of neurobiology.
|Contact: Melissa Schwarting|
Duke University Medical Center