Emily Hollenbeck, a deep brain stimulation therapy patient, demonstrates an EEG device that records brain activity as she reacts to short videos at Mount Sinai’s “Q-Lab” in New York on Dec. 20, 2023. Dr. Brian Kopell, who directs Mount Sinai's Center for Neuromodulation, says in normal brains electrical activity reverberates unimpeded in all areas, in a sort of dance. In depression, the dancers get stuck within the brain’s emotional circuitry. DBS seems to “unstick the circuit,” he says, allowing the brain to do what it normally would. (AP Photo/Mary Conlon)