UT Southwestern researchers discover new way to form long-term memories

September 20, 2016

Researchers at UT Southwestern have unlocked another mystery of the brain.

A team led by UT Southwestern psychiatry and neuroscience professor Robert Greene recently explained why people remember insignificant details about important traumatic events such as 9/11.

Photograph Credit: UTSW Media Center

“Many people can tell you exactly where they were when they heard about the towers coming down and what they did after they heard about it,” Greene said. “Some people can even tell you what they had for breakfast that morning.”

The team trained mice to dig for food in a certain spot and then measured how well the mice remembered where the food was the next day.

Additionally, they exposed one group of mice to a new environment, hoping to grab their attention soon after they found the food. When tested, this group of mice was able to more accurately remember where the food was located.

“By simply exposing [the mice] to this novel environment, we enhanced their long-term memory,” Greene said.

The process of changing memories from the short-term to the long-term involves a type of memory called a flashbulb memory, according to Daniel Johnston, director of the UT Center for Learning and Memory. When a person remembers a flashbulb memory of a particularly significant event, they also remember all of the details surrounding it, Johnston said.

According to Brad Pfeiffer, UT Southwestern neuroscience assistant professor, short-term memories, such as where you parked your car at the supermarket, are almost immediately forgotten, but this changes when significant events occurr.

“If you went to the supermarket and there was an explosion nearby, or you came out and there was a car on fire, you would probably remember where you parked your car for a long, long time,” Pfeiffer said. “The meaning of that particular day would make all these other normally mundane aspects of that day persist in your memory.”

Greene said his research confirmed that dopamine, a neurotransmitter known for enhancing memories, is responsible for storing these short-term memories through attention-grabbing events. The researchers zeroed in on dopamine from the locus coeruleus, an area that affects emotional responses and attention.

Greene said another application of this research involves helping people improve their memories.

“Say you’re studying something, and it might be hitting a little bit of tediousness at some point,” Greene said. “If you take a break and do something really interesting, maybe a new video game or something like that, and then go back to work afterwards, you’re probably going to remember the next day what you were studying much better than if you hadn’t have done that.”

The researchers also found that the mice could experience the effects of a significant event without doing anything out of the ordinary. Johnston said that artificially activating the mice’s locus coeruleus neurons had the same effect as putting them in a new environment.

Pfeiffer said potential applications, though far in the future, could change the way we learn.

“You could imagine activating that region of the brain after studying for a test, for example, and tricking the system into forcing that short-term memory to be more persistent or long-term,” Pfeiffer said.

Johnston said scientists aren’t yet sure how memories are made and stored, so this is still an area of active research.

“It’s not like we know everything there is to know about memories,” Johnston said. “I think it has a lot of practical significance from the layperson point of view, but it’s also very significant from a scientific point of view.”

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