BrainPort® is the name of a technology for visually impaired people, developed by Wicab, Inc. It is also the name of a device that uses that technology. The device involves signals received by a camera being translated into electrical pulses which are sent to the tongue. The user's brain can then convert these into visual signals and "see" the information.
Originally the BrainPort® was developed to aid stroke victims. The idea was to use a sensor to detect head positioning, then send a signal to the tongue when the head was in the "correct" position. By aiming to move the head to keep the signal active, the patient could relearn the skills needed for balance.
Later the developers found the BrainPort® could be used for more complicated signals. This was based on the fact that the human brain is able to interpret signals from one sense as having a meaning more traditionally associated with another sense. One common example of this is with Braille, where information usually conveyed in visual form is received through touch.
This concept already had a medical use through cochlear implants. These convert sound into electrical signals which are transmitted through bone to the brain. The idea is to create the same vibrations in the bone as would be produced by sounds heard by a fully hearing person.
In principle, the BrainPort®'s operation is a simple idea: a signal applied to a particular part of the tongue corresponds to a particular piece of visual information about the three-dimensional positioning and size of an object. In practice, of course, this is extremely complicated, due to the sheer complexity and variety of visual information we "see." For this reason, the level of detail which a BrainPort® user can "see" is considerably limited compared with that of somebody with normal vision. Some users have experienced good results though, with some even able to read some examples of handwriting.
The tongue is used as a sensory point because it is much more sensitive than other areas of the body. This means the strength of the electrical signal does not need to be as high. The tongue also has the benefit of being coated in saliva, which contains electrolytes and can aid the flow of the electrical current.
The BrainPort® has sparked some philosophical debate about whether or not a person using it is experiencing sight. Some believe the term should only apply when the retina is stimulated, which doesn't happen with the device. Other argue that it does not matter how visual information gets to the brain as long as it can use it.
