. tonight on "nightline," dirty minds, for men there's the famous little blue pill, but what about the ladies? meet the researchers who think they have proven the key to a woman's sexual satisfaction may be all in her head. saturday night special, you know vegas is for gambling, girls, and gluttony. now, you can add automatic assault weapons. we visit sin city's most fatal attraction. judd unplugged. she's got a new role as one tough mother. tonight ashley judd talks about training to play ex-can cia agent, why she ditched hollywood, and why she came

back. this is "nightline," march 19, 2012. good evening. tonight we begin with one of mother nature's most enduring puzzles, female sexuality. it's been more than a decade since viagra became the go-to for male sexual dysfunction. now a team of scientists has an intriguing hypothesis, for the ladies. when it comes to achieving climax, we may have been fixating on the wrong body part. >> just make yourself comfortable. relax. >> reporter: you'll never believe what these women are doing. it's the subject of documentary and scientific studies. >> are you nervous? >> a little nervous. yeah. cameras. >> the performance in question, requires kate to master bait to orgasm inside a less than

romantic mri machine? >> are you ready? >> i'm ready. >> barry and his team of researchers here at rutgers university are monitoring every detail of her climax. >> her pupils are dilating. >> all in the name of nuro science. >> orgasm is one of the most all-encompassing phenomenas in the brain. >> today the great the debate is about whether it's a physical or mental problem. by investigating the brain's reaction, kate is helping these scientists unlock the secrets of a woman's pleasure peak. >> talk to your doctor, see if america's most described treatment is right for you. >> when viagra became a blockbuster drug in the 90s, as many as 30 million men were diagnosed with erectile dysfunction, given prescription

for the little blue blue or a slew of others. it's a 5 billion business. >> when it dime women, remember when harry met sally -- >> yes, oh, oh, oh, god! >> and guess what, almost 25 years, half of us women say we still fake it. and the reason may be this. as many as 75% of us don't have an orgasm during intercourse. kate's book, girty minds, splors the notion that the problem so far is that we're attacking the wrong part of a women's body, that for them, the brain is our most powerful sex organ. this is a brain, and this is a brain having an orgasm. >> basically it's the whole brain. >> okay closely at beautiful agony.com. can you tell this is pleasure or pain? the only other event that affects your brain that much is

an ep leaptic seizure. >> sexual activity has to be pleasurable. >> not too long ago kate was happily married with a superb sex life, then gave birth to her son. >> i think it's common after you have a child, your sex life suffers. >> she says her libido crumbled and so did her marriage. she set off to find how love and lust impacts the brain. >> when you saw your brain all lit up, what did it look like? >> it looked like a christmas tree, everything was glowing. i was astounded. >> they hope to find answers for ladies lacking sexual desire, especially the roughly 10-15% of women who can't have an orgasm at all. >> where does the blockage occur in those people? >> reporter: when women take viagra, it gets blood circulating, but doesn't produce

orgasms. >> in order to develop the drugs, they had to have a disorder. 18 of the 19 doctors had ties to 22 drug companies. >> reporter: liz tanner's documentary, orgasm inc follows a quest for the holy grail, f drchlt a approval to treat female sexual dysfunction. they launched trials with creams and gels and sprays. at the time, one survey suggested that 43% of women aged 18 to 59, had some kind of sexual dysfunction which meant a lack of desire or pleasure or painful intercourse. >> reporter: what would the motivation be for making women feel like they have a disorder when it comes to their sex life? >> they're saying to wall street there's a huge market here if we come up with a women's viagra.

>> there's one approved device. >> i can always get there. >> every time? >> she's exaggerating. >> most experts don't think there will be a pill for women. >> really it may be just trying something new, being open, being able to communicate and getting outside your commfrt zone. >> reporter: but it's something of a catch 22 for married ladies. studies show having a new lover improves your sexual arousal. porn can work too, but there are other scientifically proven ways to spice things up. >> vibrators seem to help. being more experimental, liven it up. >> we live in a country where we can't say orgasm on the air sometimes. we're still debating whether or not there should be birth control allowed. >> we lived in a country where people are obsessed about sex

and also very hung up about it. we need to get over that. >> our sexual happiness depends on it. >> what's an orgasm like for you? >> um, i'm going to say that it's like a blooming flower. >> let the online debate begin. upnext, you can take aim at everyone, from bin laden to the next. ♪ [ male announcer ] the 2012 m-class continually monitors blind spots, scans the road to reveal potential threats, even helps awaken its driver if he begins to doze. so in the blink of an eye it will have performed more active safety measures than most cars will in a lifetime. introducing the all-new 2012 m-class. see your authorized mercedes-benz dealer for exceptional offers through mercedes-benz financial services.

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"nightline" continues from new york city with juju chang. there is no place like las vegas, but if you're bored with the slot machines, shopping, and the show girls, then these guys might have the thrill you're looking for. it's machine gun vegas, a special shooting range where customers can indulge in heavy ammunition. the target of their choice, the newest high-priced thrill hitting sin city. >> reporter: in las vegas, revealing costumes are parfor the course. but unlike the cocktail waitresses, these pretty girls are packing heat. >> can i assume that thing is loaded? >> maybe i'll keep that as a secret. >> she's a hostess at machine guns vegas. >> i think people make the mistake of when they see an attractive girl with a gun, they think we're taking topless dancers and giving them guns and

saying shoot. >> these are veterans? >> air force, army or navy. >> wounded warriors, some of them. >> i just got out in june. i went to afghanistan and got hurt and got sent back in december. >> hurt badly? >> i'm recovering. >> it's really different. in the military, we're mean. and here -- >> dressed like angelina jolie in the tomb raider movie, they offer customers a smorgas board of shooting options. among them the world of war package, cllding an ak47 and an m 16. the mob package includes a slnsed handgun and a tommy gun. or there's a seal team package. >> i know they call this place sin city. is this just one more sin that hasn't been tapped yet? >> l i mean, it's in the

constitution, so i don't think it's a sin. but when in vegas, do something you can't do at home. >> reporter: this bachelor party couldn't resist living out their american dream. back in london, most of the cops don't even carry guns. americans, too, can't resist the lure of guns. this guy is here for his 21st birthday party. >> guns are cool. shot them in video games, but never fired a real weapon. >> he has now. >> people like things that go bang. the bigger the gun, the bigger the bang. >> reporter: the gun rambo used so effectively. even with the noise-muffling headphones, you feel every shot. >> unbelievable. >> people have all the same glow

in their eye after they shoot it. it's hard to explain. machine guns vegas has a variety of targets to choose from, from terrorists to zombie. >> but you need silver bulgets for that one. >> can you bring in a picture of your boss? >> we did ask that. >> the most popular target seems to be osama bin laden. what's missing here is an overt nod to the consequence of guns, especially with all that cash in the casinos a few blocks away. >> reporter: it's your responsibility to make sure a criminal doesn't take that gun and head over to caesar's palace. >> yeah. i won't give you the details of our security, but suffice to say, we have very good security. >> that's a scenario you've thought of, though? >> without a doubt. >> reporter: they say they're also concerned for the other obvious concern. the drunken bachelor party, reen

acting the hang over, eager to shoot guns. >> we're only open to 8:00. we have people come earlier, rather than sort of plan on us being the last stop. >> is there booze? >> no. >> reporter: it's doubtful they'll document their other bachelor party adventures as thoroughly as this. >> this is the one thing you can tell your fiance about. >> exactly. >> reporter: this may be the only thing that happens in vegas they'll end up posting on facebook. i'm david wright for "nightline" in las vegas. >> thank to david. just ahead, ashley judd talks about her new role and rolling with the punches. multi-policy discount. paperless discount. paid-in-full discount. [yawning] homeowner's discount. safe driver discount.

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ashley judd has long been one of america's sweethearts. in fact, she was once one of the highest paid women in hollywood. now after stints at rehab and harvard, she's landed a new tv series called missing. the road hasn't been easy and tonight we have an interview with the star. >> reporter: after watching ashley judd beating and shooting bad guys in the new abc show "missing," this was a position in which i did not hope to find myself, about to get punched by her. >> but i just miss you.

you turn to the camera, right? >> yeah. >> so you actually hit me? >> i did. >> missing is about an ex-cia agent who's son has been kidnapped. >> i am a mother looking for her son. >> do you do all that yourself? >> i can wear the t-shirt that says, i do all my own stunts. >> do you think you could mess somebody up for real if you had to? >> i absolutely know that i could. >> so do not mess with ashley judd or you'll get hurt. >> reporter: you might be asking yourself as you watch her chase villains on this new show, where has she been lately? turns out for the past six years, she's been spending her time doing charity work in refugee camps and getting an advanced degree at harvard. we all know ashley judd as one-third of the famous judd

family. her mom and sister became country icons with hits like, give a little love. while ashley starred in blockbusters like, "kiss the girls." and double jeopardy. but bankruptly, she basically gave it all up and went on a deeply personal inner journey facing serious demons approximate. >> in the early part of the last decade, you were one of the highest paid actresses in hollywood and it wasn't doing it for you. why not? >> simply put, i wasn't in recovery yet. >> the shift happened in 2006 when she visited her sister winona at a place called shades of hope where winona was being treated for an eating disorder. it was there that ashley got a surprise. >> reporter: the people at the center said to you, you should check in. >> yes.

>> you didn't say forget about it, i'm fine. >> i said, i'm so tired of holding in all this pain. >> reporter: she said she was suffering depression and pain. from a childhood of sexually abuse and also experienced long periods of abject loneliness as her mom and sister were launching their music career. >> how has that affects you? >> i absolutely know that my parents love and adore me, and i'm grateful that today we have a good relationship. >> reporter: it was after 42 days in that rehab center that she made her enormous life change, retiring from acting and throwing herself into working with aids patients and victims of sexual violence, a mission that has, in her words -- >> given me a wonderful opportunity to share my recovery with them, and that's what makes life worthwhile.

the dark spath becomes something incredible. >> if i had tried to kill you, you'd be dead. >> reporter: she said it was a desire to be creative again that provoked her to sign on to the new tv show. although she insisted that her two dogs and five cats be on set. one of those dogs, chug, was with us during the interview. she's a registered psychological support dog. s and here's how she trained for those fight scenes. yoga. it's not a bad way to prepare to fight. she showed me some basic moves in a hotel gym. >> for a guy in jeans and a work shirt, you're going good. >> reporter: then left me in the dust. >> i think i have a deviated septum once from a face plant. >> reporter: a hollywood heroin as fierce and funny as ever. >> so what's next for