Artificial Eyes and Ears

The science fiction fantasy of replacing damaged organs with artificial ones is becoming a reality more and more. Researchers have been working for years at artificial replaces, called prosthesis, for damaged eyes and ears. Researching on auditive prosthesis are specially focused on the mechanisms which electrically stimulate the auditory nerve. These are made in order to help people whose cilia cells have been destroyed but whose auditory nerve remained functional. The majority of these devices insert an electrode in order to stimulate the neurons on the bazilar membrane. The deaf person uses a microphone and a microchip which analyze the frequencies and then send a small electric signal to the right spot found in the cochlea. This type of stimulation imitates how the resonant waves stimulate the cilia cells for the different frequencies. This kind of implant is called cochlear implant.

They have been already assembled on over 10,000 persons with severe deafness. The majority of those who benefit from these devices can discriminate very well between the different frequencies and many of them can recognize talking. The interesting fact is that it seems that there is a critical timing or an optimum moment for implanting this device. Deaf children who had this system installed before they were 5 years old they could learn to speak easier than children who received it after. Nevertheless, for the adults, those who got deaf later in life seem to have more benefits than those who became deaf earlier in life. For very small children the advantage might be due to the fact that their cerebral centers for hearing and talking are passing going through important developing changes in childhood years.

For adults, the older they are the higher the chances are to have heard a great variety of sounds, fact that might have prepared them for the understanding of the new weird sounds generated by the implant. Furthermore, there are some hopes that cochlear implants will permit a large variety of auditory experiences for persons with this form of deafness. There is also hope even for those who don't have the anatomic and functional integrity of the auditory nerve, but this implant is still under testing.

The development of artificial eyes for blind people is not that advanced as the one of artificial ears, presented above. The existing problem is not about capturing a visual image, for even a video camera is able to do that. The real problem is converting the visual image in a form that can be processed by the brain. Researching focused on a direct electric stimulation of the visual cortex of blind volunteers with the premise that if it is known what a person sees when different portions of the cortex are stimulated then it might be possible to evoke certain visual experiences by controlling the stimulation. The next step would be to use a video camera in order to form the image of what is in front of the blind person and then to evoke the sensation of the same image on the cortex.

The results obtained until this moment suggest that we are very far from achieving the development of an artificial eye. When a certain region of the cortex is stimulated with a weak electric signal the person has rudimentary visual sensations. These were described as small lights, different in size, from the size of a rice bean to the one of a coin. The majority of this lights were white and only some were colored. If there are simultaneously stimulated several regions of visual cortex, the spots of lights appear concomitantly. Even though the multiple stimulation of the brain gives the basis of rudimentary form of the visual pattern, it is still doubtful that this approaching will lead to the successful development of eye prosthesis. The neural processing of the visual information is so complex that is very slightly possible that it could be duplicated by artificial means.

In conclusion, science has recently made important steps which affected various domains of life. One of them is the body health domain in which the new contributions led to magnificent changes. A perfect example is an artificial ear for the deaf people. A greater challenge is represented by the making of an artificial eye, but with these fast discoveries, who knows what is to come?