Researchers at Yale University Medical School and the Olin Neuropsychiatry Research Center at the Institute of Living in Hartford, Conn., have taken a pretty good look at what happens in the brain of a drunken driver.

And it isn’t pretty.

Using imaging scans, the scientists compared the neural activity that flickered on and off like lights on a police car as both sober and inebriated test subjects played a driving simulation game.

The maps of activity in different areas of the brain revealed in new detail the impact that drinking has on a complicated mental task such as driving.

“No one had seen that in a scanner before,” said Dr. Godfrey Pearlson, a Yale psychiatrist and director of the Olin Center.

Pearlson and Vince Calhoun, a researcher at Yale and Olin, first conducted brain scans on sober drivers as they played the driving simulation game and then as they watched others play the game.

Subjects were then given a low dose or a high dose of booze — enough to get their blood alcohol content to either 0.04 percent or 0.10 percent.

An inebriated driver often will speed because alcohol has affected the cerebellum, a primitive area of the brain involved in motor function, the researchers found. But drunken drivers weave in and out of traffic because of errors in the frontoparietal cortex, which translates sensory information and helps in the decision-making process, Pearlson said.

Drinking did not seem to change activity in five other areas of the brain associated with driving, such as vision centers, the researchers found.

But to the surprise of no one, the more the subjects drank, the more trouble they had with their driving.

“They speeded up on corners, where most people slow down, and crashed more often into other vehicles,” Pearlson said of his soused test subjects.