Fly Study Could Help UTEP Researchers Understand Human Addiction, PTSD

Kyung-An Han, Ph.D., associate professor of biological sciences and director of the Neuroscience and Metabolic Disorders Project at The University of Texas at El Paso, has identified a crucial molecule in fruit flies that helps with reward-based learning and memory, a concept known as appetitive stimulus.

“The question is how flies learn the cues that predict pleasure versus punishment, or appetitive versus aversive memory,” said Han, whose findings were recently published in the prestigious Journal of Neuroscience. “It’s about basic learning and memory mechanisms, and the paper that we published is on the molecule that is critical to form good, but not bad, memory.”

The research results could eventually be applied to humans to learn more about addiction and post-traumatic stress disorder (PTSD) – afflictions that are connected to memory formation. According to Han, understanding basic fly memory and the genetics behind it could help scientists better understand the genetics behind memory formation in humans. Fruit flies serve as a powerful model for uncovering learning and memory mechanisms due to their extensive genetic resources.

“I don’t think one can transmit what we learn in flies to humans directly, but what we learn in flies can provide a baseline to look for genetic variations or environmental factors in humans that show a common thread with fly information,” Han said.

The research team, made up of Han, fellow UTEP researchers Young-Cho Kim and Junghwa Lim, and Hyun-Gwan Lee from Pennsylvania State University, designed the experiments testing the flies’ ability to learn and form memory using appetitive and aversive conditioning.

For the conditioning, flies were exposed to odors that were associated with electric shock (aversive) and sugar (appetitive), and watched to see their preference or avoidance of the odors.

The team found that fruit flies who had a deficient octopamine receptor OAMB showed “severely impaired acquisition” of good memory, but normal acquisition of bad.

Octopamine is responsible for the “fight or flight” response in fruit flies, and plays a major role in learning and memory. Its counterpart in humans is norepinephrine.

Han, who would eventually like to work with people who have addiction problems and PTSD, said that drug addicts tend to have stronger memory about the cues predicting pleasure of drugs, while those who are not addicts have a balance of both good and bad associations. In people with PTSD, stronger painful memories are formed.

 “Professor Han is an outstanding scientist who uses unique models to study addiction,” said Robert Kirken, Ph.D., professor and chair of UTEP’s Department of Biological Sciences. “Her work is very novel in trying to utilize technology and genetics.”