husband. >> his wife has never spoken about what happened until now. battery-powered brains. an experimental surgery that can literally change people's minds. >> it felt fantastic. i didn't care what was doing it. >> is it a cure for depression? revealing investigations. fascinating characters. stories with impact. this is "cnn presents" with tonight's hosts, randi kaye and drew griffin. >> 15 years ago congress knew it had a big problem. its military housing was in a desperate state. 180,000 units around the world built cheap and now falling apart. >> facing a billion-dollar repair bill, congress had a big idea. turn the housing over to private companies and let the free market do its work. >> but as cnn's deborah feyerick reports, for many families living in those homes that big idea has been a disaster. >> and the men and women who served to protect us are fighting a losing battle at home. >> reporter: when these sailors and marines left the u.s. to serve their country, no one imagined many would come home to this. so you know people who are affected in this house? >> yes. >> reporter: and then over in this house? >> mm-hmm. >> reporter: and that house. norfolk naval base in virginia is the largest in the world. home to the u.s. atlantic fleet. but it's facing a crisis. >> i'm in essence combatting a war on two fronts. >> i don't feel safe in these houses. i've never not felt safe in a house. >> reporter: a crisis that has turned dozens of military families, their children and pets into virtual refugees. holed up in cramped hotel rooms for weeks at a time. they call this hotel wing the mold wing. >> she was hospitalized. >> reporter: displaced families who tell us they or their kids are sick after living in rotting homes and being exposed in some cases to unhealthy levels of mold. roughly how many times have you either been to a doctor or been to the emergency room because of your illnesses or the illnesses of your kids if you had to guess? half a dozen times? >> 50. >> yeah. >> reporter: 50? >> yeah. >> they told me it was stress. they told me it was stress and a panic attack. until they found the lesions on my brain. >> i lost all mobility on my left side in october. they thought i was having a stroke. >> reporter: although a direct link is hard to prove, symptoms described by these young women are consistent with possible effects of mold exposure. according to the centers for disease control and the world health organization. military wives who were getting sicker and sicker say their living conditions were ignored or covered up by a private management company. lincoln military housing, or lmh, is a subsidiary of one of the largest property management firms in america. after congress privatized military family housing, lincoln partnered with the navy in 2005. taking control of renovating old homes and building new ones in the norfolk area in exchange for guaranteed rent. the navy was thrilled. >> our long-term partnership with lincoln has been extremely successful. we've been able to accomplish things in terms of providing quality homes i don't think we ever would have accomplished. >> reporter: jarel bliss runs lincoln military housing. under the terms of the contract, within a two-year period all homes were supposed to be brought up to a suitable level. was that done, in your opinion? and by "suitable" i mean all of them livable. >> yes. i believe it was, under the terms of our agreement with the navy. we have an obligation to the families. we want to provide them great housing, suitable housing, comfortable housing. >> me blamed our mold on our dogs. >> reporter: yet military spouses we spoke with tell a very different story. >> the second story was sinking into the first. >> my house is like a moat. it lives in a puddle of water. >> reporter: a story of decaying homes and well-meaning but incompetent maintenance people. >> right here is my home. >> reporter: shelley federico moved into lincoln military housing october 2010. when she moved out a year later, she had filed more than two dozen complaints with lincoln maintenance related to water damage and penetration. >> they would send someone out and they would say miss federico, no problems. we just need to caulk your window. >> reporter: shelley says she developed intense stomach and sinus problems, persistent headaches, skin lesions and chronic fatigue. doctors could find no cause. but she says it clicked the day a maintenance man came to remove a section of bedroom wall. >> he started taking the insulation out of the walls, and as he was carrying it through my house there was water dripping out of the insulation that he had just gathered from the wall. as soon as he did that, i immediately started projectile vomiting. my eyes started to swell. it started to get very hard for me to breathe. >> reporter: when shelley demanded a mold test, lincoln instead explained the company had decided to move shelley and her family to a new home. >> when i asked lincoln military housing, they told me that there was no need for a test. >> reporter: she says lincoln refused to consider mold as a possibility. who had it done independently? all of you? paying up to $500 each, shelley and others hired their own mold inspectors. results confirmed what they already suspected. so one of the readings was 33,000. what's a normal reading? >> zero. i was actually told by our mediator you're very lucky that you found it when you did. if you would have continued to live this way this whole time not knowing, you would probably be dead. >> reporter: all right. this is shelley federico's house. lincoln's gerald bliss took us to see shelley's former home, which remains vacant because it's now the focus of a lawsuit. there's a smell in this house. and i understand whether it's just general must. but there's a distinct -- >> yeah. that's just -- >> reporter: -- just heaviness in this house. no? you don't smell it? >> well, i do a bit. but -- >> reporter: we asked about the high levels of mold spores in shelley's test. >> there's been three other reports that have been completed. >> reporter: and what did they tell you about this house? >> they had low levels. >> reporter: lower levels than the report that i saw? >> yes. >> reporter: but cnn reviewed two of the mold reports. both of which confirmed significant levels of mold. lincoln could not share the results of its own independent test because it's being sued by military families. lincoln knew it was inheriting hundreds of older, poorly built homes. while bliss denies a systemic mold problem, he admits maintenance fell short. >> i understand why some of the families are frustrated in this issue. i'd be frustrated, too, with some of the things that went on. we've made mistakes and we're working through those mistakes. >> reporter: but that's not good enough for the families. lincoln is now fighting a lawsuit by shelley and others that claims the company's failure to properly maintain their homes caused them serious health problems. >> you know, we're sending our men and women to go fight for this country. we don't ask for a mansion on the hill. we just ask for a safe place to lay our head at night that's not going to make us sick and it's not going to make our family sick. that's all we ask. >> reporter: when we come back -- was lincoln trying to save costs, to cut corners? >> 100% yes. 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[ male announcer ] one pill a day. 24 hours. zero heartburn. lincoln military housing did not create the navy's deteriorating housing crisis, decades in the making. but it didn't fix it, either. as a result, many military families are living in toxic homes. deborah feyerick's special investigation continues. >> reporter: as the new landlord lincoln military housing did put in new appliances, fixtures, cabinetry and carpeting, taking homes from this to this. but it appears aging homes continued to be plagued by water damage. persistent leaks. and more harmfully, mold. and more and more families were falling mysteriously ill. what kind of illnesses have you had? >> sinus infections. respiratory infections. the nausea. the vomiting. the diarrhea. >> reporter: the families we spoke to believe lincoln was avoiding what it knew to be a huge problem. >> there was a lot of mold when i first started. >> reporter: meet dinette smith. she worked ten years for the navy and was among the first team hired by lincoln when it took over military housing in 2005. in your opinion, was lincoln trying to save costs, to cut corners? >> 100% yes. they did not want to spend the money due to the units eventually were going to be torn down or they mainly concerned on 100% occupancy. >> reporter: how were they remediating the mold? >> covering it. >> reporter: how? >> they would cover it with cleaning it with bleach and then painting over it. they put a band-aid over anything the cheapest way possible to make it not visible and for a resident to come in to not say anything. >> reporter: lincoln denies smith's allegations. she was fired for overspending on housing maintenance. fast-forward to today. with families getting mysteriously sick and lincoln denying a problem. families desperately turn to the navy for help. >> she was actually there with me that day. >> it's out of our hands. >> it's out of our hands. there's nothing we can do. i found a doctor that could help us. you know what? you see those helicopters over there? that's what i do. and i don't do anything more than that. i said, sir, you're the rear admiral, can you help us? "i'll pass the information along." >> reporter: that man is rear admiral tim alexander whose housing staff directs service members to lincoln housing. >> we're there to support our families and to ensure that they are being treated properly. >> reporter: and from the bottom of your heart, do you believe that the navy acted that way? because a lot of families would say otherwise. >> i do believe that in every instance where we were informed that they had a problem with their landlord we have fully engaged on their behalf, yes. >> reporter: the navy's housing crisis came to a boil in december when a local tv reporter contacted by marine wife shelley federico started looking into the allegations. >> after shelley's story spread through the neighborhood, other navy families started coming forward, telling news channel 3 their stories. >> reporter: the floodgates opened. navy and marine wives who had never met before came out by the dozens. at an emergency town hall meeting, u.s. senator mark warner, who himself has a daughter with asthma, listened in disbelief. >> it's been 20 years in business. this is not a way to run a business. >> what struck me was here were these navy spouses with their husbands deployed defending our country. and they were living in substandard housing. i mean, this is not how we should be treating the families of the guys who are defending our country. >> reporter: when lincoln tried to defend itself with its own test results suggesting no mold was present, senator mark warner demanded lincoln fire its mold inspectors. telling the navy to step in and do its job, overseeing its public/private partnership with lincoln. many of the families feel the navy dropped the ball when it came to oversight. do you think that's a fair description? >> i think the navy, if they didn't drop the ball, they took their eye off the ball. >> reporter: lincoln is now doing what desperate families for months have been asking. they're finally offering free mold tests for anyone who wants one. and, if necessary, remediating the mold. lincoln and the navy are not doing this out of the goodness of their heart. they're doing it because they got caught. >> they got caught. >> reporter: lincoln says it has fired ten employees, hired a community liaison, and is reviewing its 4,400 homes. lincoln representatives were denying there was a problem. the navy was denying there was a problem. now all of the sudden there's been a 180-degree reversal. and you guys are now acting on it. >> well, we've made mistakes. and we're not happy about what happened here. and i think we've -- we've recognized that. >> reporter: it's no secret that government contracts are lucrative contracts. but devil's advocate, why should anyone give you any more money given what has happened with these families? >> well, we have to -- we have to prove ourselves again. and we have to compete for the families, their rental dollars. >> reporter: the navy is now promising to live up to its end of the deal. >> one of our lessons learned has been in this particular partnership and for the time being that we need to increase the amount of oversight that we provide sort of at the deck plate level. >> that's what they found in my bathroom. >> reporter: you're asking these families who already have enough going on to trust lincoln and to trust you, and a lot of families are saying, uh-uh. >> well, certainly we want to restore that trust across the board. and we will do that one family at a time. >> reporter: but for those who are sick and feel they were lied to, that could take a very long time. >> these things should have been condemned a long time ago. and they weren't. i don't want to move back into that house. i don't care what they've done to that house. they can rip out every single wall. they can rip up every piece of carpeting. it's not going to be safe. >> to date, lincoln military housing has inspected nearly all of its 4,400 homes. so far they say 68 homes have required full remediation. but despite their track record, the company gets to keep that lucrative navy contract for the next 40 years. up next, he left behind an anger-filled manifesto and a wife who says she still loves him. in an exclusive interview, the widow of a man with a vendetta against the irs tells her story. ♪ [ acoustic guitar: slow ] [ sighs ] [ announcer ] all work and no play... will make brady miss his favorite part of the day. ♪ [ upbeat ] [ barking ] [ whines ] that's why there's beneful playful life, made with energy-packed wholesome grains... and real beef and egg. to help you put more play in your day. beneful. play. it's good for you. standard keyless access, and standard leather-trimmed seats, then your choice is obvious. the lexus es. it's complete luxury in a class full of compromises. see your lexus dealer. cuban it's complete luxury in a class full of compromises. cajun raw seafood pizza parlor french fondue tex-mex fro-yo tapas puck chinese takeout taco truck free range chicken pancake stack baked alaska 5% cash back. right now, get 5% cash back at restaurants. it pays to discover. we asked total strangers to watch it for us. thank you so much, i appreciate it, i'll be right back. they didn't take a dime. how much in fees does your bank take to watch your money ? if your bank takes more money than a stranger, you need an ally. ally bank. no nonsense. just people sense. two years ago a man named joe stack crashed his plane into the office building that housed the irs in austin, texas. before flying on his deadly mission, he burned down his own home, leaving behind a wife and stepdaughter who had fled in fear to a hotel the night before. he also left a manifesto online in which he angrily railed against the irs. what really happened? and who was joe stack? the woman who knew him best, his wife, sheryl, has not spoken about the tragedy until now. kyra phillips has her story of faith and fury. ♪ >> i still love joe. i don't think that joe was a bad person. >> reporter: it took some time for sheryl stack to get to this point. for two years, she has struggled, but has found comfort in her music and her faith. >> i have been more sad than mad. suicide is so painful on so many different levels, and then you add the public factor, the public suicide. ♪ >> reporter: it was february 18th, 2010. an angry and violent joe stack set his family's house on fire, then drove here to the georgetown municipal airport, -- >> georgetown tower, dakota 2889 ready for departure. >> 89 delta clear for takeoff. >> what's your direction of flight, sir? >> 89 delta going southbound. >> reporter: at 9:49 a.m. joe stack was headed for his final flight. joe stack knew exactly where he was going. the echelon building in austin. which housed the irs. >> from austin, texas a single-engine aircraft has crashed into a seven-story building. >> it was like a fire bomb. people let out a scream all around me. a few people were crying. >> reporter: stack slammed his plane between the first and second floors of the building. it exploded on impact. one man was killed. vernon hunter, an irs employee. >> the country, the city, the region in danger. >> reporter: immediately, there were fears that this was an act of terrorism. but it wasn't. it was simply one man's grudge against the irs. and then came the manifesto. before stack would die by suicide, the 53-year-old software engineer would leave behind a rambling diatribe online where he railed against the government in excruciating detail. "i choose to not keep looking over my shoulder at big brother while he strips my carcass," stack wrote. i choose not to ignore what is going on all around me. i have just had enough. ♪ >> reporter: today, that manifesto still haunts sheryl stack. what do you say to people that may be listening to you and thinking, how could she not know about this rage, about this manifesto, about this anger? >> well, i knew that he was angry. but i thought he was angry at us. you know? about the irs, i didn't know that he was violent. how could i possibly know he would do a thing like that? >> reporter: sheryl met joseph andrew stack through a mutual friend in 2005. both loved music. sheryl played piano. joe played bass guitar. two years later in a small ceremony in austin they married. joining them was sheryl's 12-year-old daughter, margo. so what made you fall in love with joe? >> well, he was really sweet and funny and smart. >> reporter: so you both loved music? >> we both loved music. and he also was a private pilot. and he had his own plane. >> reporter: did he ever talk about how he was angry with the government, angry with the irs? >> when we were dating, he did talk about the irs. and he didn't seem so angry. he just didn't like them. >> reporter: what would he say? >> you know, that he thought they were crooks, you know. that they were above the law. >> reporter: but actually, joe's emotions ran much deeper. in the '80s while living in california, he was part of the anti-tax movement. even forming his own tax exempt home church. his run-ins with the irs continued for decades. then in late 2008, joe and sheryl got audited. and once again, joe was in another battle with the irs. a battle he wasn't going to lose. joe stack started to document what would soon become his suicide mission. he wrote, "desperate times call for desperate measures." and "violence not only is the answer, it is the only answer." >> he said they're never going to leave me alone. >> reporter: when do you think he was writing this manifesto? >> one day he was writing. whenever i would walk into the room where he was writing, he'd just turn his attention to me. >> reporter: so when you walked in, he closed the computer. he had something he didn't want you to see. >> but i didn't know what it was. and so a few days before that horrible day when everything -- i don't know what to call that day. i don't know what to call that day. but a few days before that he was writing, and i walked in. i said, honey, what are you writing? are you writing a journal? are you keeping a journal? and he said, "something like that." coming up -- >> i saw the smoke billowing and i said, oh, my god. he's burned the house down. >> reporter: the tape you haven't heard. sheryl tells austin's arson investigator what she knew in the hours leading up to her husband's final flight. [ male announcer ] this is the at&t network. a living, breathing intelligence helping business, do more business. in here, opportunities are created and protected. gonna need more wool! demand is instantly recognized and securely acted on across the company. around the world. turning a new trend, into a global phenomenon. it's the at&t network -- securing a world of new opportunities. ♪ we now return to "cnn presents" with your hosts tonight, randi kaye and drew griffin. >> in the hours before joe stack burned down his house and crashed his plane into the irs building, his wife and stepdaughter fled to a hotel. >> what really happened on that last night sheryl stack saw her husband alive? kyra phillips continues our story, "faith and fury." >> reporter: this is what's left of the home that joe stack burned down. is it hard to come back here? >> that's hard to answer. it's -- it's not as hard as it was initially. it was really hard right after it all happened. >> reporter: among the rubble, reminders of a different joe stack. a burned guitar case. and this message of faith. >> everything was just completely black and covered with soot. and there were some boards with nails sticking out of it. and on one of these boards was this -- looked like a white flag. and i went over and picked it up and turned it around and it was this irish blessing. it was a tea towel. and it wasn't burned. >> reporter: the only thing still hanging in that entire house. >> everything was completely burned. >> reporter: ironic, considering what joe did. sheryl says in the months before he began acting differently. he became more angry with the irs and the audit. he started to blame sheryl and her daughter, margo, for all his problems. and he became increasingly strict with margo. sheryl talked about divorce. tension continued to build. and according to austin police records, sheryl said that joe had "threatened her daughter on previous occasions." even threatened to break her neck. life with joe was getting odd and more unbearable. >> he said that we were the cause of all of his troubles. >> reporter: wow. >> but that was at the same time that he was giving me a birthday card and saying, you're the best thing that ever happened to me in my whole life. >> reporter: then came their final night together. everything seemed fine. sheryl was giving a piano lesson. margo, who was only 12, was preparing dinner with joe. what would happen next would change their lives forever. >> after we had dinner, we sat down in the family room and i -- he was just talking, like he just wanted to leave. and he said he was just going to disappear. but we didn't really know what he was talking about. i said, mom, he's not even taking a toothbrush with him or anything. like, where is he going? this is kind of scaring me. >> reporter: so did you think he might do something that wasn't right? >> i kind of had, like, a feeling that something was going to happen, like something bad. and i told my mom that i wanted to leave. and she said, okay. and so we left. >> reporter: sheryl took her daughter to this nearby ramada inn. she never heard from joe again. the next morning, this is what sheryl drove up to. in this interview obtained by cnn, listen to what sheryl tells the fire department's arson investigator. >> i saw the smoke billowing and i said, oh, my god. he's burned the house down. and then i figured he was in it because he's suicidal. i figured he was in the house. so i couldn't wait to see his car. you know, once i realized he burned down our house and everything in it, i hope he's in the house. because if he's not he's still at large and i have to be afraid for my life because he's mad at me for ruining his life. >> reporter: why would he set the house on fire? >> i don't know if it's because we left or just because he just completely blew up inside himself. i don't know. i don't know if he would have done it if we'd stayed. >> reporter: two years later, do you ever find yourself saying, oh, my gosh, my gut was right to get out of the house that night, to get my daughter out of there? >> her gut was right. she may have saved our lives. >> reporter: the morning of the fire, sheryl and her daughter took refuge at a neighbor's home. >> we just got some information. >> reporter: it would be there she would discover the fate of her husband on the local news. >> the airplane that hit. >> they interrupted the house fire to show that a plane had crashed into a building. >> reporter: how did you react when you realized it was his plane and it was him? >> well, i don't think i did react. i think i just was just -- just in complete and utter shock. >> reporter: sheryl was left to deal with the rage that had been documented in destructive and direct detail. he wrote in the manifesto, "but violence not only is the answer, it's the only answer." >> i don't know who that is. i don't know that man. >> reporter: a man who would be secretly simmering for decades. leaving behind a rant against the u.s. tax system. and a wife who just wants to remember the joe she loved. >> i learned a lot being up in the air with joe. one of the things that i learned up there is that the sun is always shining on the other side of the clouds. it might be a really dark, dark day. it might be a terrible, terrible day. but on the other side of those clouds the sun is shining. >> kyra phillips joins us live in studio. kyra, what a revealing interview. and now an unexpected twist. >> well, we mentioned vernon hunter. and that was the only person that was killed in the irs building. he was one of the employees. and you know, she's been mourning the loss of her husband. and we thought, wouldn't that be interesting if she met sheryl and the two of them talked. i talked to sheryl about that. i had a chance to talk to valerie about that. valerie wanted to be more private. sheryl really wanted to meet her. they did. and they talked about the loss of their husbands, how much they missed them. and sheryl wanted to make it clear to valerie, look, i had no idea he was going to do what he did. and i just wanted you to know that. and i had talked with valerie's pastor, too. and he thought that the two of them meeting would do a lot for the healing process. >> how does sheryl support herself financially these days? >> that's a great question because she lost her entire home. joe stack burned it down before he flew his plane into that building. and it took a while to get back on her feet. they were bumping around, living in different places. and friends came together, donated furniture, gave them gift cards, cash. they held a benefit concert for her. so they just now moved into a new home two years later. and she's paying off that irs debt of $20,000, teaching piano. >> kyra, thanks. up next, cutting edge medicine. the story of a patient with a battery-powered brain. ♪ hey, dad, you think i could drive? i'll tell you what -- when we stop to fill it up. ♪ ♪ [ son ] you realize, it's gotta run out sometime. 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[ male announcer ] you're at the age where you don't get thrown by curveballs. ♪ this is the age of knowing how to get things done. so, why let erectile dysfunction get in your way? talk to your doctor about viagra. 20 million men already have. ask your doctor if your heart is healthy enough for sex. do not take viagra if you take nitrates for chest pain; it may cause an unsafe drop in blood pressure. side effects include headache, flushing, upset stomach, and abnormal vision. to avoid long-term injury, seek immediate medical help for an erection lasting more than four hours. stop taking viagra and call your doctor right away if you experience a sudden decrease or loss in vision or hearing. this is the age of taking action. viagra. talk to your doctor. our next story is on a subject that scares many. mental illness. because there's so much we don't understand. in any given year 5% of americans have serious mental health problems. many cases, mood disorders, ptsd, addiction, according to a government study, go untreated. but tonight dr. sanjay gupta is going to show you a new kind of surgery that literally changes the way our brains work. >> reporter: for as long as edie guyton can remember, she could not get the sad thoughts out of her head. >> my mother used to say to me, smile, edie. why don't you smile? and i would, you know, give something like that, maybe. or just think, what is there to smile about? >> reporter: at 19, her blank face reflected what would later be diagnosed as severe depression. >> that expression is the best i could -- i could do. >> reporter: what's it like to look at it now? >> i feel sorry for her. you know, i just -- i feel bad for her. that she couldn't smile. that she couldn't talk to people about, you know, what -- what is going on with her that would lead her to cut her wrists several months later. >> reporter: it was her sophomore year. academic and social pressures were the trigger. and one night -- >> for reasons that are inexplicable to me even now, got up and started playing with a razor. and -- >> reporter: you cut your wrists. >> mm-hmm. >> reporter: you cut both your wrists? >> yeah, mm-hmm. >> reporter: she went into counseling. but it didn't help. over the next 40 years she tried everything else, including psychiatric drugs and electroconvulsive shock therapy. >> and then there was a few years that i think i felt pretty good. but then i went back down. and i went back down very deep. >> reporter: there were two more suicide attempts before she conquered the demon. what finally worked? well, if you could look inside edie guyton's head today, this is what you'd see. >> i don't think about it, but i have electrodes in my brain. >> reporter: two electrodes. the thickness of angel hair pasta. powered by a battery pack under her collarbone. >> and the wire goes up here. and then into my -- you know, into my brain. >> reporter: specifically to a part of the brain known as area 25. it's an experimental treatment. >> so what are we looking at here? >> reporter: pioneered by neurologist dr. helen mayberg. >> the "x" is where we're stimulating. >> reporter: since the mid-1990s mayberg has been using high-tech imaging to study the brain circuits that control our moods. she figured out that area 25 is a junction box in the center of it all. >> okay. here we go, charlie. i know. >> reporter: mayberg's research also showed that in depressed patients area 25 is relatively overactive. >> here again, you can see area 25 except now it's red as opposed to blue because this is an increase. >> reporter: she theorized that in patients like edie guyton who did not respond to conventional treatments, area 25 was somehow stuck in overdrive. >> it just was a matter of following the experimental trail. >> reporter: the trail led to the operating room. and a procedure known as deep brain stimulation. dbs. here at emory, where i'm on staff, my colleagues have been using deep brain stimulation for more than 15 years to treat movement disorders such as parkinson's disease. in that case they're targeting the brain's motor system. but dr. mayberg wanted to use dbs to target area 25 for patients with severe depression. so beginning in 2003, working with a brain surgeon in toronto, she began testing it on six patients. it had never been done before. >> we had patients who were profoundly without any options and suffering. and we had a hypothesis. >> reporter: what did you worry about most in terms of potential side effects from actually simulating 25? >> because of its vital position, its junction box location, for all we knew, we were going to activate it and actually make people feel worse. >> reporter: instead, mayberg saw two-thirds of the patients get significantly better. she has since reported similar results for 31 others. >> and we not only get them better, but with continued stimulation with this device, they stay well. >> reporter: people who had lived in a block of emotional ice. people like edie, who had lived that way for years. >> it's not that you won't be happy or that you aren't happy, it's you can't be happy. >> reporter: not even when her grandniece, susan, was born. >> and somebody handed her to me. and i held her, but i didn't even put her face to mine. i just held her. but i was going through the motions and i felt really nothing. >> reporter: nothing? >> nothing. nothing. >> reporter: on the day of surgery, edie's head was mounted in a rigid frame. >> the sound of the drill, the feeling of it, and my teeth are going like this. i think it hit home to me that you're having brain surgery. somebody is going into your brain. actually, the milk from my farm makes it so creamy, right dad. ah, but my carrots have that crunch. it's my milk in the rich sauce coating the chicken and the pasta. boys! don't you think stouffer's steam perfect bag should get some credit? 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[ traffic passing ] ] ♪ [ music box: lullaby ] [ man on tv, indistinct ] ♪ [ lullaby continues ] [ baby coos ] [ man announcing ] millions are still exposed to the dangers... of secondhand smoke... and some of them can't do anything about it. ♪ [ continues ] [ gasping ] imagine living in a hole so dark you cannot see. so deep you cannot escape. that's severe depression. now doctors are experimenting with a cutting-edge treatment, battery-powered brains. how does it work? can it cure depression? dr. gupta continues his investigation. >> reporter: in an operating room at emory university in atlanta -- >> right now we're just going to anchor this one in place. >> reporter: -- these doctors are trying to use deep brain stimulation to turn off severe depression. >> figuring out where the blood vessels are and obviously choosing the target. is that right? >> reporter: the target is area 25. a junction box for brain circuits that control our moods. >> our patients are miserable. it's beyond sadness. they spend most of their day just sitting there often thinking, you know, why can't i just die? >> reporter: at first, patients are lightly sedated as dr. robert gross drills two holes. with an instrument to guide him, he then inserts the electrodes. to make sure the electrodes are in the right spot, we can actually listen for neurons firing in the brain. the gray matter sounds like this. the white matter is silent. and that's where they want the electrodes. the white matter just below area 25. >> we just confirmed that all electrodes are basically in the right place. >> reporter: it was a procedure just like this done on edie guyton. what were the risks? what did they tell you? >> brain damage. infection. death. >> reporter: did you have second thoughts about doing this? >> no. >> reporter: it was that bad? >> it was that bad. >> reporter: deep brain stimulation would change her life. >> is the contact on? >> contact's on. >> reporter: you could see it happen when she was wide awake in the operating room with doctors paul holtzheimer and dr. helen mayberg. >> are you okay, edie? >> as a benchmark they asked edie to rate her feelings on a scale of 1 to 10 starting with dread. >> my sense of dread is getting worse. >> rate it. >> 8. >> reporter: two minutes later, they turned on one of the four contacts. >> how does it feel right now? is it still high? >> no, it's much less. >> what's the dread right now? >> three. >> reporter: a drop from eight to three. but doctors would soon get an even better result. >> we're going to make some changes. >> reporter: remember, before the surgery edie could not connect emotionally with her grandniece, susan. then? >> on. >> reporter: they turned on contact number two. >> let me know if anything changes. just give a shout. >> okay. smiling. i just almost smiled. >> you just almost smiled? >> yeah. >> describe that for us, would you, please? >> i didn't smile -- i haven't smiled before, like, in a long time. or laughed. >> it brings tears to your eyes to see somebody that is in such pain and then that goes away. >> when you say you almost smiled, did something strike you as funny or is it just sort of spontaneous -- >> it was -- well, i -- actually, i was thinking of playing with susan. >> i started thinking about susan. little susan. i thought, i was holding -- you know, she was -- i was holding her with her face to me. right there in the brain surgery. i felt feelings that i thought were gone. >> reporter: what is that like just to think that a machine and electricity could transform your emotions like that? >> it felt fantastic. i didn't care what was doing it. it just felt great. >> spoon it in there. >> reporter: it's been five years. edie is one of dr. mayberg's most dramatic success stories. >> i don't feel good all the time. but this gives me the capacity that if i can, if there is joy in my life, i have the capacity to feel it. >> reporter: but what exactly is going on? what is dbs doing to the brain circuits? what do we and don't we know about why this works? >> well, to be brutally honest, we have no idea how this works. >> reporter: and if area 25 is so important, why doesn't everyone get better? >> maybe we're doing something wrong. maybe it's not in the right place. maybe they're not the right patient. that means we've got to understand the biology better. >> reporter: mayberg's research is part of this quiet revolution in medicine. in addition to depression, scientists are looking at dbs targets for obsessive-compulsive disorder, epilepsy, tourette's syndrome and alzheimer's. in the meantime, edie guyton is thankful for her new life. with the battery pack delivering about 1/1000 of the power that a flashlight bulb uses. do you feel any electricity or anything? >> i don't feel anything in my head at all. >> did you go off medication when you were pregnant? >> reporter: she's active with a mental health advocacy and support group. and she recently traveled to italy with old friends from college. >> and that smile is real. i was okay. >> reporter: it's only been an issue once. >> at the airport, i just go -- and i say -- and they say, "pacemaker question. and i said yes. one time, i said actually it's brain electrodes. i'll never do that again. the woman who was patting me down like she was afraid i would explode. >> boy, you got to love airport security