Recent achievements in neurotechnology are nothing short of stunning—blind people can see parts of their world again, and a woman who has been paralyzed for a decade can feed herself using a robotic arm. Leaders in the field presented these and other advances at the Aspen Brain Forum last week, while at the same time debating how quickly these technologies will lead to treatments for neurological disease and injury.

At the Aspen meeting, which was cosponsored by the New York Academy of Sciences, Robert Greenberg, CEO of Second Sight, described how his medical-device company developed a prosthetic-sight system (see “Bionic Eye Implant Approved for U.S. Patients”). In its current form, the system transmits image data from a camera to a 60-pixel implant in the retina. However, the company is talking about a future version of the system that bypasses the eye altogether and instead sends the image information directly into the visual cortex.

But despite such progress, Greenberg and many other presenters made clear that much of how the brain works—and what happens when things go wrong—remains a mystery. The U.S. government announced this spring a $100 million initiative to develop new technology to map neuron- and circuit-level activity in the brain (see “Why Obama’s Brain-Mapping Project Matters”), and the European Union is funding a $1.3 billion project to understand the brain through computer simulations. 

“It’s so difficult to get anything to work in the human brain at all,” says Ed Boyden, an MIT neuroscientist who discussed his work using light to control neural activity, which could be developed into a treatment for blindness. “It’s enormously complex, and the risk for patients is high,” he says.

But medical treatments rarely wait on a complete understanding of how the body works. And there are successes even when there aren’t complete answers. Andy Schwartz, a neuroscientist at the University of Pittsburgh, discussed his group’s research on brain-computer interfaces, which have been used by quadriplegic patients to drive a robotic arm to move objects and even feed themselves (see “Patient Shows New Dexterity with Mind-Controlled Robot Arm”).

“We are starting to see a little bit of maturation and get a better understanding of what we can and can’t do,” says Schwartz. As his work has moved from monkeys to humans, his team has uncovered details of the neural code, but there is still plenty to learn.  

Helen Mayberg of Emory University presented some of her still-experimental work treating otherwise intractable cases of depression with deep-brain stimulators. Such stimulators have been implanted in more than 100,000 people around the world. In most of these cases, the technology is used to treat mobility problems in Parkinson’s patients, but researchers have also found that they can treat a variety of neurological and psychiatric diseases (see “Brain Implants Can Rest Misfiring Circuits”).

But deep-brain stimulators are a rare example of new options for brain treatment, and Mayberg expressed frustration in the dearth of tools for human use. “We want what the animal people have to understand the choreography of the whole system,” she said, “to look at all the cross-talk between neurons and [eliminate] symptoms of psychiatric disease.”