How much is too much? Test could show the effect of gaming on your kid’s brain. originally appeared on goodmorningamerica.com

Cash, a 10-year-old boy who lives in Los Angeles, is obsessed with the game Fortnite, his mother Rusti says.

Fortnite represents the current pinnacle of game theory and player engagement. It's filled with bloodless violence, intensity and it's peppered with random surprises.

(MORE: The 'king of Fortnite' offers his tips to winning the popular, free last-man-standing game)

It's constantly being updated with pop-culture add-ons and it's filled with silly victory dances that delight the player. Because it can be played on a console, a tablet or a phone, it can travel with a player anywhere they get cellular data or Wi-Fi.

PHOTO: This illustration picture shows the video game Fortnite app logo displayed by a tablet in Paris, Feb. 18, 2019. (Lionel Bonaventure/AFP/Getty Images) More

It is one of the first totally social, play-everywhere video games, with 250 million players. Its creator, Epic Games, is reportedly valued at $15 billion.

Makings of a habit

"He asks me to wake him up 20 minutes early on school days so he can play," Rusti says of her son, Cash. "He doesn't want playdates at other kids' houses anymore … he just wants to be in the house so he can play."

Cash plays with friends from school, his cousins in Costa Rica and random strangers, and is allocated an hour of playing each school night. Rusti doesn't limit him on the weekends, and estimates he plays four to five hours each Saturday and Sunday.

PHOTO: Cash Rusti (ABC News) More

Watching Cash play Fortnite on his iPad can be dizzying as he manipulates the weapons in his arsenal. He has colorful adornments on his various avatars and when asked how he earned those skins, he says his allowance is now paid to him weekly in V-Bucks, the currency used to buy items in "Fortnite."

Rusti confirms that Cash has spent close to $2,000 in the game. "I can get him to do any chore I want if I pay him in Fortnite money," she says.

Is there is anything he'd rather be doing than playing Fortnite?

"That's a good question … but ... no!" he says.

His mom says he often screams with joy at events in the game and Cash admits he "rages."

(MORE: 'You are the boss': Parents of Fortnite-obsessed kids turn to Facebook, experts for help)

"When someone kills you or you die of fall damage and you get angry at that, and you just go insane on your tablet and you throw it," he says. He admits there are times when he forgets to eat and times when his body tells him he's played too much.

"When you're just lightheaded and you can't get enough 'Fortnite,' but it hurts inside," he says.

Effects on the brain

Andrew Newberg, M.D., a neuroscientist at the Marcus Institute of Integrative Medicine at Jefferson Health, has devised a way to illustrate some of the physiological and structural changes happening to gamers. He wants to compare a gamer's brain to a non-gamer's brain to see how the response to different stimuli affects them. Amado, a 12-year-old fellow student at Cash's school who loves music, basketball and watching movies, fits the profile of a non-gamer, occasionally playing car-racing games but who overall isn't into video games.

PHOTO: Amado mom (ABC News) More

For the experiment, Cash settled into an MRI machine while game footage was played in a monitor bolted above his face. First a control: Newberg contrasts a minute of non-Fortnite gaming video (from an older shooting game that doesn't have the neon colors, social integration or fun dances) with a minute of neutral video (birds at sunset). The neutral video is colorful and moving, so it will stimulate some of the visual regions of the brain. By playing video the older game on the monitor, Cash will see violence, action and many of the same stimuli that he sees in "Fortnite," it just won't be his favorite game. After 10 minutes, Newberg stops the imaging and gives Cash a chance to move his arms and legs. Now for the Fortnite portion: To most accurately simulate the experience of playing the game, video was recorded from Cash's iPad of his actual gameplay, complete with his avatar and favorite skins.

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