Brain knows how to integrate natural, artificial vision

Raising hope of effective treatment for age-related macular degeneration (AMD), researchers have found that the brain knows how to integrate natural and artificial vision, while maintaining information processing that is important for vision.

AMD is a common cause of severe vision loss in among those aged 50 and over.

Though there is no cure for AMD, significant recent advancements in artificial retina implants may lead to effective treatment.

"These pioneering results have implications for better restoration of sight in AMD patients implanted with retinal prosthetic devices and support our hypothesis that prosthetic and natural vision can be integrated in the brain," said the study's lead author Yossi Mandel from Bar-Ilan University in  Israel.

"The results could also have implications for future brain-machine interface applications where artificial and natural processes co-exist," said Mandel.

Located inside the eye the retina contains light receptors (photoreceptors) which absorb light. Information is then processed and transmitted to the brain.

The macula, the central area of the retina, processes most of the information that reaches the brain from the eye, enabling one to see while reading and driving, facial recognition, and any other activity that requires accurate vision.

In the peripheral retina, the area of the retina outside the macula that assists mainly with spatial judgment, vision is 10-20 times less precise.

In AMD precise vision is impaired due to damage to the centre of the retina, while peripheral vision remains normal.

When there is damage to the photoreceptor layers in the retina, an artificial retina -- a device built from tiny electrodes smaller in width than a hair -- may be implanted.

Activating these electrodes results in electrical stimulation of the remaining retinal cells and results in visual restoration, albeit partially.

AMD patients implanted with an artificial retina possess a combination of artificial central vision and normal peripheral vision.

"We used a unique projection system which stimulated either natural vision, artificial vision or a combination of natural and artificial vision, while simultaneously recording the cortical responses in rodents implanted with a subretinal implant," said Tamar Arens-Arad from Bar-Ilan University.

The implant is composed of dozens of tiny solar cells and electrodes, developed by Professor Daniel Palanker at Stanford University in the US.