The cyber-eye that sees sounds
Inspired by Geordi La Forge, the blind engineer in 'Star Trek: The Next Generation', in 2005 Nasa developed a device that allowed people with serious vision impairment to see again. Today, the challenge to restore sight has led to experimenting with the regrowth of optic nerves. A phenomenon that could come about if the command that blocks it is removed. American researchers are convinced that they are on the right path. With laboratory mice, at least. In the meantime, British bioengineering is experimenting with a new way of enabling blind people to 'see' through sound. It's something like bat sonar transferred to people. A computer converts the perimeter of objects into sounds that are then transmitted to a microchip implanted in the cerebral cortex; this is adapted to receive and recognize various sounds (parietal cortex) to give a kind of vision to those who cannot see at all.
These experiments are in addition to the development of the bionic eye: in this case, biochips are implanted in the occipital area. They receive impulses from sophisticated eyeglasses; each image is split into thousands of different electrical stimuli which are then joined up again by the biochips to recreate the image in the brain. The problem is a technical one: billions of different micro sensors would be needed to restore vision that is close to natural sight. At the moment, technology is unable to mimic nature. The most promising path is the one experimented by researchers at the Children's Hospital in Boston and which, according to them, should bring new hope to people who are totally or partially blind. Published in the journal 'Science', the work describes how they have been able to regenerate the optic nerves of laboratory mice by means of a technique that has already been successfully tried on the spinal cord. The damaged optic nerves in mice repaired themselves in a few weeks. Unlike nerves in limbs, the spontaneous regrowth of nerves in the brain and spinal cord is blocked by a protein. American researchers have been able to prevent it by 'switching off' the protein. Two weeks after treatment, half the optic nerves in animals recovered from damage compared to 20% in untreated animals. And in 10% of cases there was significant growth.
Specifically, the technique acts on two genes, PTEN and TSC1, which are responsible for the formation of the protein that blocks nerve regeneration. Scientists are optimistic: it is possible to create drugs that mimic the same effect in humans. Obviously it will take many years. The device that converts images into sounds has, however, been set up by the department of bioinformatics at Oxford University in Great Britain. The system 'teaches' the brain to associate a series of sounds with different objects. The volunteers who took part in the experiment were able to perceive the objects in front of them by using the part of the brain that 'reads' sounds and the part that 'reads' images. A camera is fitted onto eyeglasses and the images are analyzed by a computer which converts perimeter lines and edges into sounds with different tones, frequencies and intensity. After a few weeks' training, patients were able to recognize different objects through sounds. Neuroscientist Colin Blakemore, who coordinated the research with Petra Störig of the Heinrich-Heine University in Düsseldorf, Germany, verified that the patient's brain reacted as if he had really seen the objects. On the negative side, the system works only for people who have memorized images because they once had sight but lost it due to illness or trauma. Soon to come on the market is the 'bionic eye'.
It has been tried on tens of patients, who were able to perceive light and distinguish faces and movement. Mark Humayun of the University of Southern California, explained: «Our aim is to convert the images from a camera into electrical impulses that 'force' a sightless eye to see'. The system should restore the sight of anyone suffering from retinitis pigmentosa or macular degeneration. A very small camera on the eyeglasses sends the images to a small computer which the patient can keep in a pocket. The information is processed and sent back to the glasses, which will then transmit it to electrodes implanted in the retina and therefore to the optic nerve connected to the brain. The entire process takes place at the speed of light. The only problem is technical development: at the moment it is possible to implant 16 electrodes in the brain, equal to 16 pixels in a photograph. We are going to try with 60 electrodes. But to imitate real sight more will be required and in microscopic areas. Scientists are convinced they can do it.
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