Neuroscientists could help people see with their "mind's eye"
June 6, 2012
A team of researchers at the University of Texas is exploring the possibility of electrically stimulating the visual cortex of the brain to create simple images and shapes. This development could lead to a visual prosthetic device that would effectively "trick" the brain of visually impaired or blind people into seeing ... and such a device, the authors say, is only about five years away.
We see with the eyes, but we can also "see" with just our brains. According to widely respected neurologist Oliver Sacks, approximately ten percent of visually impaired people experience lucid hallucinations, a condition known as Charles Bonnett syndrome. Such hallucinations are generated by hyperactivity in the visual cortex, and can be exquisitely detailed.
The team led by Prof. Michael Beauchamp is investigating activity in the same portion of the brain that artificially generates phosphenes - or the illusions of a flash of light. If properly controlled these could allow anyone, including those who are blind, to see simple shapes, letters and numbers.
In time, the team would like to see the development of a visual prosthetic device that allows people to see with their own minds. Such a device could work by integrating a webcam in the frame of the subject's eyeglasses: the tiny camera would wirelessly relay information to a computer chip implanted in a person's brain. The chip would then stimulate the appropriate parts of the visual cortex to allow the brain to experience images.
Surprisingly, the authors say this can be achieved in the not-so-distant future.
"We are probably about 5 years from such a technology, even though there are a number of obstacles," Professor Beauchamp told Gizmag. "An important one is the difficulty of creating and implanting small biocompatible devices that work in the long-term without risk to the patient." It should be noted, however, that at this stage it is unclear just how detailed the images generated by such a device would be.
For the time being, the researchers are only able to generate one phosphene at a time.
"At this point, we cannot control the shape, size or color of each individual phosphene, although some phosphenes do have color," says Beauchamp. "For each phosphene, a separate electrode has to be placed in the brain and separate circuitry has to be used."
The team now plans to conduct a larger study and create multiple flashes of light at the same time. They believe that around thirty simultaneous flashes might be enough to allow participants to see the outline of a letter or a simple shape.
"While much work remains to be done, the possibilities are exciting. If successful, we would in essence bypass eyes that no longer work and stimulate the brain to generate mental images," says Beauchamp.
The findings were detailed in the journal Nature earlier this week.
Source: University of Texas