Brain implants that deliver electrical pulses tuned to a person’s feelings and behaviour are being tested in people for the first time. Two teams funded by the US military’s research arm, the Defense Advanced Research Projects Agency (DARPA), have begun preliminary trials of ‘closed-loop’ brain implants that use algorithms to detect patterns associated with mood disorders. These devices can shock the brain back to a healthy state without input from a physician.
The work, presented last week at the Society for Neuroscience (SfN) meeting in Washington DC, could eventually provide a way to treat severe mental illnesses that resist current therapies. It also raises thorny ethical concerns, not least because the technique could give researchers a degree of access to a person’s inner feelings in real time.
The general approach — using a brain implant to deliver electric pulses that alter neural activity — is known as deep-brain stimulation. It is used to treat movement disorders such as Parkinson’s disease, but has been less successful when tested against mood disorders. Early evidence suggested that constant stimulation of certain brain regions could ease chronic depression, but a major study involving 90 people with depression found no improvement after a year of treatment.1
The scientists behind the DARPA-funded projects say that their work might succeed where earlier attempts failed, because they have designed their brain implants specifically to treat mental illness — and to switch on only when needed. “We’ve learned a lot about the limitations of our current technology,” says Edward Chang, a neuroscientist at the University of California, San Francisco (UCSF), who is leading one of the projects.