. >> what did tdc s do? what is it used for? >> it's almost surprising how broad the applications are. almost every neuropsychiatric disorder like schizophrenia and depression and cognitive enhancement. >> how do you respond to people who say it is snake oil. >> i have used that analogy myself. if i provided you something in a vial and said it will help you with depression, make your niece better at math and in one vial because i'm making so many claims it stops being believable. the simplable -- simple answer is it's not one thing in a vial. it's where we put the electrodes on the head and combine it with training and behavioral therapy. >> coming up: i put another kind of brain stimulation to the test. weird. we would -- want to hear what you think about these stories. >> just going to check. >> okay. >> in dozens of clinical trial around the world a new technique for transcrannial direct stimulation is being used for a range of issues. >> where they put the electrode on the head is intentional. you might put it for motor regi