Playing video games increases aggression in some children and young adults and normalizes killing, some doctors said.

Research suggests that violent video games can make children feel different. A brain scan of a teenager who has just played what was deemed a nonviolent video game was compared to the scan of a teen who had just spent 30 minutes playing a violent game. Indiana School of Medicine researchers said highlighted areas in the brains showed increased activity in the areas involved in emotional arousal.

"Exposure to violent video games, even E rated video games, increases aggressive thoughts, increases pro-social behavior and increases general arousal," said Dr. Greg Snyder, a psychologist at Omaha's Children's Hospital.

Snyder said exposure to violence in video games can desensitize a teen to the real thing.

Research from Iowa State University, Kansas State University and the National Institutes of Health reached similar conclusions. Compared to teens who played nonviolent games, those who played violent games had a lower heart rate and lower galvanic skin response when they were exposed to videos of real violence, the studies showed.

"The more normal it is, the more likely it is they're going to activate or engage in those behaviors when provoked or even unprovoked," Snyder said.

Tyler White, 17, said he has been playing video games as long as he can remember. He and his friend, Erik Grove, 16, play a game called "Gears of War." Both boys said they enjoy shooting games.

"With a shooting game, you can't actually go out and shoot someone," White said. "The whole thing with video games is, do something you can't already do in real life, at least that's what it is to me."

After they played the game for about 20 minutes, the teens said they didn't feel more violent.

The video game industry notes that the research also finds that teenagers have similar responses to violence in movies or TV. The industry said no one can prove a definitive link between virtual violence and the real thing.

Ryan Miller, the manager of general operations for Gamers in Omaha, said video games become an easy scapegoat when children turn violent.

"Just like any new media, it gets attacked. When any new genre of music comes out, it gets attacked. TV will, of course, get attacked. I'm sure, way back when, books got attacked," Miller said.

Other research shows that antisocial behavior is not a result of the game, but rather the isolation that results when children play the games along for hours on end.

All sides of the argument agree that parental control is important, whether it's in the purchasing of games or playing them.

Lora and Chuck Payne said they don't restrict the types of games their son, Tyler, plays, but they do give him a time limit. Chuck Payne said he knows some teens who are allowed to play for hours a day.

"Then, when they're done playing, that's all that's on their mind. Kill. Kill. Kill. Well, one hour a day. Period," he said.

The Paynes said they have not noticed a change in the son's aggression level after a gaming session, but they watch what he plays and they talk to him about the games he chooses.