Although there are already eye implants that allow blind people to see simple patterns, scientists in Spain have recently had success with a different approach. They bypassed the eyes, producing noticeable images by directly stimulating the visual cortex of the brain.
The experimental system includes a forward-facing “artificial retina” mounted on an ordinary pair of eyeglasses worn by the user. This device detects light from the visual field in front of glasses and converts it into electrical signals that are transmitted to a three-dimensional array of 96 microelectrodes implanted in the user’s brain.
The implant is only 4mm wide and each of the small electrodes is 1.5mm long. They enter the brain so that they can both stimulate and monitor the electrical activity of neurons in the visual cortex, located in the larger cerebral cortex. This stimulation allows the person to perceive the light patterns transmitted by the artificial retina.
Last year, a 1,000-electrode version of the setup was tested successfully on primates, although the animals were not blind. More recently, however, a team from Spain’s Miguel HernÃ¡ndez University tested the current version on a 57-year-old woman who had been completely blind for over 16 years. After an internship where she learns to interpret the images produced by the camera, she is able to identify the letters and silhouettes of certain objects.
Importantly, the implant was found not to otherwise affect the function of the cerebral cortex, nor to stimulate adjacent non-target neurons. In addition, the implant required a much lower electric current than the similar electrode arrays that are placed on the area of the brain, potentially making it safer to use. The device was removed six months after implantation.
There is still a lot of work to be done before the technology can be used on a practical level, so scientists are now recruiting blind volunteers for further experiments. These could consist of stimulating a greater number of neurons simultaneously, in order to produce more complex images.
An article on the research, which was edited by Prof. Eduardo FernÃ¡ndez Jover, was recently published in The Clinical Investigation Journal. A somewhat similar system is under development at Monash University in Australia.
Source: RUVID Association