A new generation of surgically implanted neuromodulation devices is making regulatory headway with one recent approval from the US Food and Drug Administration (FDA) and a positive recommendation. In November, the FDA granted premarket approval to Mountain View, California–based NeuroPace's responsive neurostimulation system (RNS), a pulse generator implanted in the brain that detects and disrupts epilepsy seizures by delivering normalizing electrical neurostimulation. The system is approved for individuals for whom two antiepileptic drugs fail to control seizures. More recently, in February, the FDA's Anesthesiology and Respiratory Therapy Devices Panel recommended approval of the Inspire II Upper Airway Stimulator, developed by Inspire Medical Systems, of Maple Grove, Minnesota, to treat obstructive sleep apnea in individuals who have failed continuous positive-airway pressure treatment. The device implanted under the chest skin senses breathing patterns, delivering mild stimulation to the airway muscles and the hypoglossal nerve, which runs beneath the base of the tongue, to keep the airways open during sleep. These 'closed-loop' systems are a dramatic departure from previous neurostimulation devices as they rely on sensors to anticipate neurostimulation needs. Joseph S. Neimat, an associate professor of neurological surgery at Vanderbilt University in Nashville, Tennessee, says, “What we've done in the past is a one-way stimulation model.... You pretty much put the stimulator in, you turn it on, you let it fire X number of times in a particular pattern.” Instead, the closed-loop stimulators “listen,” he says. As knowledge of brain function continues to grow, “There are going to be more proposals in front of the FDA for devices like this,” Neimat predicts.