Every thought, feeling, sensation, and idea you have is encoded in little electrical impulses that travel through the neurons in your brain. Misregulation of these impulses is implicated in every disease of the nervous system. Until recently, neurons were largely unobtainable; and the electrical impulses traveling through them were invisible. These two challenges hampered efforts to develop new medicines for the brain. New advances in stem cell biology now allow scientists to reprogram skin cells into neurons, providing a readily available source of neurons from healthy people and from patients with genetically based diseases of the nervous system. Dr. Cohen’s lab introduced a gene from a Dead Sea microorganism into neurons, which converts neural electrical impulses into flashes of fluorescence. This has resulted in high-speed movies of electrical impulses traveling through human neurons in a dish allowing them to study the molecular basis for a wide array of neuronal diseases.