Rome: "Internet pornography changes children's brain cells", says American neurosurgeon Donald Hilton.
At a world congress this week in Rome on the sexual dangers facing children in the digital world, Hilton warned against the devastating effects of violent pornographic web clips on young brains.
His concern is shared by Pope Francis, who on Friday received the 150 experts of the congress at the Vatican and urged the world to take action.
Following are three questions Hilton, from the University of Texas Health Science Center in San Antonio, answered on the issue.
What happens in a child's brain when viewing large amounts of pornographic web films?
Our brain cells change with learning. Addictive learning sculpts the brain in a very damaging way and we can become very set in certain behaviours and tastes.
When there is a reward like pornography, that's a specially powerful printing process. The brain doesn't forget that. A 12- year-old who sees hardcore porn is going to say 'Wow that was amazing'.
Sometimes children may be frightened, but the fascination overcomes the fright eventually.
One thing our brain wants is novelty, change. It wants a different face, a different body shape. Boys, and increasingly girls, are struggling with porn. They literally surf for hours looking for the perfect clip to masturbate to.
There is a lot of scientific evidence that sex can, and in particular internet porn, be addictive. It's like a blackjack game, it's a different set of cards every time.
Will they necessarily want to imitate what they see?
Porn is destroying the ability to feel emotion. And the push for teen girls to allow boys to perform painful anal sex on them was described as coercion in a recent study of a British medical journal.
Ninety-three percent of boys and 62 percent of girls under the age of 18 have been exposed to internet pornography. And a review of the 250 most popular pornographic films found that 88 percent of the scenes contain physical aggression towards women.
Men also get to the point where real women are just bad porn and they are more interested in porn than having a relationship with a real woman.
And virtual-reality porn films are arriving with fantastic new technology used for simulators. It's quite expensive but a lot of porn producers are really investing in this right now.
I believe the porno-fied culture is affecting everybody.
Are young actors and actresses, growing up in this porn culture, also victims?
Pornography is a very exploitive industry. Young female performers are used up in two years. They call it "shot out" within two years. There are A, B and C girls. By the time they are a C girl, they have to do pretty violent stuff to still get the phone call. And there are so many new ones conditioned by their culture, coming to the set "porn ready".
For so long porn has been relegated to the moral and religious realms. Let's leave religion out and talk from a public health perspective.
Can we really say that porn is good and that everyone should view it if the people that make it are being harmed?
Porn is filmed prostitution.
During Roman times thousands of people and animals were killed in the colosseum and spectators enjoyed it. I think we have a neon colosseum of screens, where far more people are enjoying people getting harmed.
I think we are worse than the ancient Romans. At least they did it openly, but we hide behind our screens at night and tell us it's OK.
We must not allow pornographers to control the sexual education of our children. We call upon lawmakers to protect the children.
