When Dr. Conor Liston first began mapping the brains of people suffering from major depression he noticed something strange. In depressed brains certain networks were expanded and, as a result, had pushed into other networks. This finding made Dr. Liston think that the expanded network could explain why depression presents differently from patient to patient. His work mapping the brain could be the key to effectively using Transcranial Magnetic Stimulation (TMS) to help patients with treatment resistant depression.