Your heart is racing, your palms are sweating and your hands are trembling. You are now at the front of the seemingly never-ending line at the zero gravity ride. It’s your turn.

Sound familiar?

The UA will host its 42nd annual Spring Fling this weekend. The event provides over 40 games and rides to roughly 32,000 attendees every year. Among these rides, however, there are certain attractions that typically draw those who crave that adrenaline rush. These people, known as sensation seekers, are constantly searching for that next dangerous adventure to get their fix.

Whether it’s traveling 30 mph down the Flagstaff slopes or being strapped to a drop tower released at 60 mph, adrenaline junkies are always seeking that euphoric feeling that goes along with a sense of danger. It turns out there is a scientific explanation behind this phenomenon.

David Zald, neuropsychologist and professor of psychology and psychiatry at Vanderbilt University, discovered that risk takers actually have fewer dopamine autoreceptors in the brain, allowing for more free-flowing dopamine.

Dopamine is a neurotransmitter that regulates the brain’s reward and pleasure centers, among other things. In fact, street drugs such as heroin, cocaine and methamphetamine act as these dopamine receptors, confusing the brain’s reward system by producing an intense feeling of euphoria.

Dopamine autoreceptors are responsible for inhibiting dopamine in the brain. Since risk takers have fewer autoreceptors, thrill-seeking activities result in a greater than normal dopaminergic responses, which increases that feel-good feeling.

Stephen Cowen, assistant professor of psychology at the UA, said there are physiological differences for those seeking new experiences compared to those who do not.

“We have seen evidence that there is a difference in neural circuitry in those who are thrill seekers,” Cowen said. “Think of the mind as being in either of two states: seeking novel experiences or going with what you are comfortable with.”

Cowen said there are two different ways in which dopamine could influence risk behavior. These are background dopamine and the rush of dopamine associated with exciting activity.

“When you go sky diving, for example, you may have a higher level of background dopamine and it’s that surge of dopamine that results from jumping out of a plane that reinforces that behavior,” Cowen said.

In other words, those of us constantly searching for new and exciting experiences may have higher levels of background dopamine.

“We’ve actually seen evidence of this in patients who have Parkinson’s Disease,” Cowen said. “In PD, patients have a diminished amount of dopamine in the brain. However, when we supplement them with dopamine, we see increases in risk-taking behavior such as gambling.”

For those eager to get their hearts pumping in a G-rated and campus-sponsored way instead of through a dopamine rush, Spring Fling begins Friday at 4 p.m.

Follow Akshay Syal on Twitter.