Restoration of normal function has driven development of devices such as cochlear implants for deafness, deep-brain stimulators for Parkinson's disease, and bionic eyes for the blind, but there has long been a fascination with using similar technologies to "neuroenhance" healthy individuals, helping them control emotions, improve memory and cognition, and even communicate wordlessly with others.
Speakers at a 19 September session on neuroenhancement co-hosted by AAAS and the Dana Foundation urged separating hype from hope, and stressed the value of currently available neurostimulation devices to improve the lives of those with disabling conditions. Over the longer term, they said, any efforts to move beyond therapy to "enhancement" must weigh legal, ethical and social concerns as well as the medical risks and benefits.
"If we are capable of enhancing, should we and how?" asked Daofen Chen, program director in systems and cognitive neuroscience at the National Institute of Neurological Disorders and Stroke. "Is it desirable? What's the goal and the consequences?" There already have been efforts to enhance learning with prescription stimulants dubbed "smart" pills, but Chen said there is no evidence that such pills truly improve cognitive abilities through a known biological mechanism.
Both in science and science fiction, the specter of neural enhancement and control has long been debated. Joseph Pancrazio, head of the department of bioengineering at George Mason University, noted the work of Jose Delgado of Yale University in the 1960s. He used an implant to stimulate a region of a bull's brain called the caudate nucleus. Delgado stepped into a bull ring and, when the bull charged, pressed a remote control button which caused the animal to stop in its tracks.
Delgado claimed the stimulus caused the bull to lose its aggressive instinct, and spoke of a future when such methods would allow "a less cruel, happier, and better man." Michael Crichton, a student of one of Delgado's collaborators, offered an alternative view. In his novel The Terminal Man, a man with an electrical implant to control his epilepsy becomes a vicious killer.
While the fascination with neuroenhancement endures, Pancrazio noted that the risks of brain-machine interfaces are not insignificant, even for some of the devices currently available. For deep brain stimulation, there is a 5% risk of infection, he said, and a 2% risk of stroke due to bleeding in the brain.
Nonetheless, neurostimulation devices "are a clinical reality for a large number of individuals who are living with disability," Pancrazio said, and their benefits "truly are life-restoring for many individuals." They also are a big business (a $2.6 billion market in 2012, according to one study) and new devices continue to emerge.
Pancrazio cited an estimate that there are now more than 700,000 stimulation devices in use worldwide for various neurological conditions, including spinal cord stimulators for chronic pain, sacral nerve stimulators for urinary incontinence, deep-brain stimulators for essential tremor, dystonia and Parkinson's disease, and cochlear implants for hearing loss.
In February, the U.S. Food and Drug Administration approved the Argus II bionic eye for "humanitarian use" in treatment of retinitis pigmentosa, an inherited, degenerative eye disease that often results in profound vision loss. The device, available in Europe since 2011, converts video images captured by a miniature camera, housed in the patient's glasses, into electrical pulses that are transmitted wirelessly to an electrode array on the surface of the retina. These pulses stimulate the remaining retinal cells, producing light patterns in the patient's field of view.
Ramez Naam, a computer scientist and author of More than Human: Embracing the Promise of Biological Enhancement, noted researchers also have made strides getting data out of the brain via interfaces that allow, for example, a paralyzed patient to move a prosthetic hand just by "thinking" how it should move.
"In my opinion the most powerful impact these technologies could have someday, probably decades and decades in the future, is by enhancing the ability of humans to communicate," said Naam, who titled his talk "Networked Minds." He described an experiment at Wake Forest University in which two capuchin monkeys in separate rooms were linked by an interface implanted in the auditory cortices of their brains. When a sound was played for one animal, the other was able to recognize it.
In another recent experiment, a researcher at the University of Washington, wired up to an electroencephalography (EEG) machine, sent a brain signal via the Internet to a colleague across campus, causing the colleague's right index finger to move on a keyboard. He wore a cap with a transcranial magnetic stimulation (TMS) coil that sent the signal to the brain region that controls movement of the right hand.
While there are very real issues about the cost and control of technologies capable of human enhancement, Naam said, "I am an optimist. The long-term trajectory of information technology, which is how I view this in a way, is positive."