It’s an electrifying time to be in neuroscience. Using implanted devices that send pulses of electricity through the nervous system, physicians are learning how to influence the neural systems that control people’s bodies and minds. These devices give neurologists new ways to treat patients with a wide range of disorders, including epilepsy, chronic pain, depression, and Parkinson’s disease.

So far, these stimulators have been one-way devices that deliver a steady sequence of pulses to the nervous system but can’t react to changes in the patient’s body. Now, at last, medical device companies are coming out with dynamic neural stimulators that have a bit of “brain” themselves. These smart systems can detect changes in a physiological signal and then respond by delivering a therapy or adjusting the patient’s treatment in real time.

The three of us work for companies on this technological frontier, building devices that take advantage of developments in low-power implantable sensors and embedded signal processing. In this article we’ll describe three devices that respond to the flux of biology within the body. Because these devices rely on data related to the processes they influence, we call them “closed-loop” systems, but you could also call them the next step in a bionic model of medicine. In this new paradigm, engineered systems composed of chips, wires, and batteries can replace or supplement biological systems that malfunction.

An epileptic seizure starts with a storm of abnormal electrical activity in the brain. In the most common adult form of the disorder,…[Read more]