Standing before a projected image of a giant fly in a liquor store, Kyung-An Han, associate professor in biology, concluded her lecture, "Addiction: A Bad Case of Good Memory."

The lecture, the second installment of the Frontiers of Science lecture series, gave Han the opportunity to correct some the misconceptions about drug addiction to an audience of 330 people in the Thomas Building Saturday.

Han proposed that addiction is a chronic and progressive illness and is not a problem based solely on willpower.

"There is still quite a bit of prejudice against the actions of drugs in the brain," Han said. "Addiction is not really a moral issue. Our behavior is controlled by brain functions."

In the past year, 18.2 million people aged 12 or older met the criteria for alcohol dependence or abuse, Han said.

Other legal drugs like cigarettes and illegal drugs such as marijuana and cocaine are highly addictive because of their effects on the brain, she said.

Drugs affect the "reward" pathway in the brain, an area that mediates feelings of pleasure. Natural rewards that affect the reward pathway include eating food and having sex.

Dopamine is essential to the brain for feelings of pleasure. The dopamine binds to receptors in the brain, and after the initial bind, the dopamine is reabsorbed, Han said.

Stimulants like cocaine and amphetamine mimic dopamine and bind to receptors. The difference is that after they bind, they block the reabsorption of dopamine, therefore increasing pleasure, she said.

Continued drug abuse induces neuronal adaptation in the reward pathway of the brain, altering brain functions and metabolism, Han said. This leads to tolerance and the drug's effects become weaker over time or more of the drug is needed to produce the desired effect. Physical dependence and withdraw results after continued drug abuse, Han added.

Long-term damage results after sustained drug abuse. Addicts have an overall decline in motor and cognitive skills and are highly vulnerable to relapse, she said.

Han explained that memory can be tied to drugs and their effects on the brain.

"Drug-related images or stimuli activate the brain regions for emotional memories and trigger craving," Han said.

"Drug users have enhanced memory of drugs but have blunted memory of natural rewards."

Vulnerability to addiction is based on several factors, including genes, environment, brain function and behavior, she said. Initial use can lead to abuse and eventually to addiction.

To illustrate her point, Han discussed her research with alcohol and flies. The research involved giving flies doses of alcohol and monitoring them to record how long it took them to "pass out."

Early on, the flies were more hyperactive than normal and passed out within 20 minutes. Days later, they found that the flies had developed a tolerance to the alcohol's effects and that it took more alcohol and more time for the flies to pass out.

Because teenagers' brains are still developing, their initial response to the drug will be greater, Han said. According to Han, by age 20, the changes that drugs cause in the brain are more likely to stick and become hardwired as addiction by adulthood.

Erin Stover (senior-biology and psychology) and Jen Dunning (senior-chemical engineering and life science) work with Han and the fly research and experiments in her lab.

Dunning said she thought the research was particularly beneficial for Penn State students.

"Every weekend you see all the bars, everybody out there drinking away, and it's just a mess," she said. "This kind of research is good to make people aware of the situation on college campuses."