Deep brain stimulation is the bleeding edge of mental health treatment. Originally developed to treat the terrible tremors that patients with Parkinson’s disease suffer from, some researchers now view it as a potentially revolutionary method of treating mental illness. For many patients with mental health disorders like depression, therapies like drugs are often insufficient or come with terrible side effects. The numbers are all over the place, but doctors and researchers generally agree that significant numbers of people don’t respond adequately to current treatment methods—one often-cited study pegs that number somewhere around 10%-30%. But what if doctors could simply open up the brain and go directly to the source of a problem, just as a mechanic might pop open the hood of a car and tighten a loose gasket?