Is it possible to relieve depression or PTSD using electricity? Kelly Bijanki, PhD, runs a lab at Baylor College of Medicine, where her team is using deep brain stimulation to induce happiness in patients who need it the most. Her fascinating work shows that "emotional" issues are as biologically based as "neurological" ones, and that depression can be treated with the same techniques used for epilepsy or Parkinson's disease. Plus… the evolution of the smile.