These startups have seen investment from NEA, Andreessen Horowitz, and DARPA, among many others. As the digital health sector matures from basic tracking apps into highly regulated medical devices, we are seeing bleeding edge technologies being developed that blur the lines between computers and biology. And a growing share of these startups are beginning to target the brain. The burgeoning field of neurotechnology involves brain-machine interfaces, neuroprosthetics, neurostimulation, neuro-monitoring, and implantable devices intended to not only augment nervous system activity, but enhance its capabilities. One such project is Elon Musk's Neuralink which is developing, "high bandwidth brain-machine interfaces to connect humans and computers."

William Kochevar of Cleveland can slowly move his right arm and hand. No big deal--except that the 56-year-old had been paralyzed from the shoulders down since a bicycling accident ten years ago. The setup that is allowing Kochevar to move his arm again is a "neuroprosthetic" involving two tiny recording chips implanted in his motor cortex and another 36 electrodes embedded in his right arm. Now, during visits he makes to an Ohio lab each week, signals collected in his brain are being captured and sent to his arm so he can make some simple voluntary movements. "I was completely amazed," says Kochevar.

The Modular Prosthetic Limb will help patients to feel and manipulate objects just as they would with a native hand. Sitting motionless in her wheelchair, paralysed from the neck down by a stroke, Cathy Hutchinson seems to take no notice of the cable rising from the top of her head through her curly dark hair. Her gaze never wavers as she mentally guides a robot arm beside her to reach across the table, close its grippers around the bottle, then slowly lift the vessel towards her mouth. Only when she finally manages to take a sip does her face relax into a luminous smile. This video of 58-year-old Hutchinson illustrates the strides being taken in brain-controlled prosthetics1.