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Abstract
A new device has been developed by the scientist which helps blind people to see. This device has a shape of electric lollipop and captures images using a ting camera. The images are converted into tingles on tongue and send to the brain. The brain then converts these tingles into images. This device is also known as a tasting device because it can taste and sense objects. This device is based on the idea of sensory substitution, the process in which if one part of brain is damaged then the part of brain that would normally control the damaged part learns to perform some other function. Within few hours of training this device can help visually impaired people to recognize high contrast objects, their locations and some aspects of perspective and depth. The device is still in investigation and has not been launched commercially but the results obtained after testing the device on blind people were astonishing and have indicated that there is a huge scope of application for this technology in future. The present paper deals with an opportunity for blind community to interact with the vision of the world through innovative development of electronics and computer engineering.
INTRODUCTION
In a laboratary , a congenitally blind women holding a video camera sits in front of a scientist.(fig.1) She has a device touchig her tongue in her mouth ,and there are wires running from that device to the video camera. When the experiment begins the scientist starts to do simple gestures with out giving any additional hints to the women. Surprisingly ,the blind women can see things through her tongue and follow what the scientist does!
The name of the device in her mouth is called “Brain Port Vision Device”. Basically, the device sent visual input through her tongue in much the same way that seeing individuals receive visual input through the eyes. In both cases, the initial sensory input mechanism-the tongue or the eyes-sends the visual data to the brain, where the data is processed and interpreted to form images. Technically this device is underlying a principle called electrotactile simulation for sensory substitution, an area of study that involves using encoded electric current to represent sensory information and applying that current to the skin ,which sends the information to the brain. Most of us have been familiar with Braille, a typical example of sensory substitution ,which uses one sense touch, to take in information normally intended for another sense vision. Fundamentally, electrotactile stimulation is just a higher tech method of receiving some what similar but more surprising result. They are both based on the idea that the brin can interpret sensory information even it is not provided via the natural channel. In the 1960s,this process was the subject of ground breaking research in sensory substitution at the Smith-kettlewell Institute led by Paul Bach-y-Rita , MD, Professor of Orthopedics and Rehabilitation and Biomedical Engineering at the University of Wisconsin, Madison. Nowadays , in becomes the bases for Brain Port Vision technology.
Electrotactile Stimulation for Visual Substitution
When a human looks at an oject , the optical image entering the eyes does not go beyond the retina. Instead, it would turn into spatio-temporal nerve patterns of impulse along the optic nerve fibers. By analyzing the impulse patterns, the brain recreates the images .Indeed , the channels such as eyes, ears and skin those carry sensory information to the brain are set up in a similar manner to perform similar activities. To substitute one sensory input channel to another, the big challenge to the scientist is how to correctly encode the nerve signals for the sensory event and send them to the brain through the alternate channel as the brain appears to be flexible when it comes to interpreting sensory input.
The concepts at work behind electrotactile stimulation for sensory substitution are complex, and the mechanics of implementation are no less so. The idea is to communicate non-tactile information via electrical stimulation of the sense of touch. In practice, this typically means that an array of electrodes receiving input from a non-tactile information source (a camera, for instance) applies small, controlled, painless currents (some subjects report it feeling something like soda bubbles) to the skin at precise locations according to an encoded pattern. The encoding of the electrical pattern essentially attempts to mimic the input that would normally be received by the non-functioning sense. So patterns of light picked up by a camera to form an image, replacing the perception of the eyes, are converted into electrical pulses that represent those patterns of light. When the encoded pulses are applied to the skin, the skin is actually receiving image data which would be then sent to the brain in the forms of impulse.
Under normal circumstances, the principle lobe (Fig.2) in the brain receives touch information, while the optical lobe receives vision information. when the nerve fibers forward their image-encoded touch signals to the tactile-sensory area of the cerebral cortex, the parietal lobe.
Within this system, arrays of electrodes can be used to communicate non-touch information through pathways to the brain normally used for touch-related impulses. It's a fairly popular area of study right now, and researchers are looking at endless ways to utilize the apparent willingness of the brain to adapt to cross-sensory input. Throughout the past few decades , they have been developed to send the encoded current to the fingertips, abdomen are back. The break through of the Brain Port technology is to use tongue as the substitute of sensory channel.
The Advantages of Brain Port Technology
Compare to all other skin areas ,the tongue skin area is the most sensitive one because there are more nerve fibers and they are much closer to the surface. Moreover, there is no stratum corneum(an outer layer of dead skin cells)on the tongue which acts as an insulator. With these characteristics, it requires less voltage to stimulate nerve fibers in the tongue(5 to 15 volts)compared to areas like the fingertips or abdomen(40 to500 volts). Also, since the tongue is surrounded by saliva which contains electrolytes, it would help to maintain the current flow between the electrode and the skin tissues. Last but not least, the area of the cerebral cortex that interprets touch data from the tongue is larger than the areas serving other body parts. Therefore, the tongue is the best choice of conveying tactile based data to the brain until this moment .
The Structure of the Brain Port Vision Device
According to the department of opthamology at University of Washington, 100 million people in the United States alone suffer from visual impairment. This might be age-related, including cataracts, glaucoma and macular degeneration, from diseases like trachoma, diabetes or HIV, or the result of eye trauma from an accident. BrainPort could provide vision-impaired people with limited forms of sight.
To produce tactile vision, BrainPort uses a camera to capture visual data. The optical information -- light that would normally hit the retina -- that the camera picks up is in digital form, and it uses radio signals to send the ones and zeroes to the CPU for encoding. Each set of pixels in the camera's light sensor corresponds to an electrode in the array. The CPU runs a program that turns the camera's electrical information into a spatially encoded signal. The encoded signal represents differences in pixel data as differences in pulse characteristics such as frequency, amplitude and duration. Multidimensional image information takes the form of variances in pulse current or voltage, pulse duration, intervals between pulses and the number of pulses in a burst, among other parameters.
Laboratory Test Result of the Brain Port Vision Device
After training in laboratory tests , blind subjects were able to perceive visual traits like looming, depth, perspective, size and shape. The subjects could still feel the pulse on their tongue , but they could also perceive images generated from those pulses by their brain. The subjects perceived the objects as “out there” in front of them, separate from their own bodies . They could perceive and identify letters of the alphabet . In one case, when blind mountain climber Erik Weihinmayer was testing out the device , he was able to locate his wife in the forest .One of the most common questions at this point is” Are they really seeing?”It all depends on how you define vision. If seeing means we can identify the letter “T” somewhere outside yourself, sense when that “t” is getting larger, smaller, changing orientation or moving further away from your own body then they are really seeing.One study conducted PET brain scans congenitally blind people while they are using the Brain Port Vision device. It found that the vision centers of the subjects ‘brains lit up when visual information was sent to the brain through the tongue after several sessions with Brain Port. If ‘seeing” means there is activity in the vision centre of cerebral cortex, then the blind subjects are really seeing. While the Brain Port test results are somewhat astonishing and lead many wonder about the scope of the applications about the technology, we would see which other applications of Brain Port Vision Device scientists are currently focusing, and what other applications it foresees further technology in the next section.
Current and Potential Applications of the Brain Port Technology
While the full spectrum of BrainPort applications has yet to realized, the device has the potential to lessen an array of sensory limitations and to alleviate the symptoms of a variety of disorders. Just a few of the current or foreseeable medical applications include:
• providing elements of sight for the visually impaired
• providing sensory-motor training for stroke patients
• providing tactile information for a part of the body with nerve damage
• alleviating balance problems, posture-stability problems and muscle rigidity in people with balance disorders and Parkinson's disease
• enhancing the integration and interpretation of sensory information in autistic people
Medical Applications
Beyond medical applications, Wicab has been exploring potential military uses with a grant from the Defense Advanced Research Projects Agency (DARPA). The company is looking into underwater applications that could provide the Navy SEALs with navigation information and orientation signals in dark, murky water (this type of setup could ultimately find a major commercial market with recreational SCUBA divers). The Brain Port electrodes would receive input from a sonar device to provide not only directional cues but also a visual sense of obstacles and terrain. Military-navigation applications could extend to soldiers in the field when radio communication is dangerous or impossible or when their eyes, ears and hands are needed to manage other things -- things that might blow up. Brain Port may also provide expanded information for military pilots, such as a pulse on the tongue to indicate approaching aircraft or to indicate that they must take immediate action. With training, that pulse on their tongue could elicit a faster reaction time than a visual cue from a light on the dashboard, since the visual cue must be processed by the retina before it's forwarded to the brain for interpretation.
Other potential BrainPort applications include robotic surgery. The surgeon would wear electrotactile gloves to receive tactile input from robotic probes inside someone's chest cavity. In this way, the surgeon could feel what he's doing as he controls the robotic equipment. Race car drivers might use a version of Brain Port to train their brains for faster reaction times, and gamers might use electrotactile feedback gloves or controllers to feel what they're doing in a video game. A gaming BrainPort could also use a tactile-vision process to let gamers perceive additional information that isn't displayed on the screen.
Conclusion
Even though this is a field of scientific study that has been around for nearly a century , it has just picked up in this decade due to the miniaturization of electronics and dramatic improvement of the computer’s speed. Already more streamlined than any previous setup using electrotactile stimulation for sensory substitution, BrainPort envisions itself even smaller and less obtrusive in the future. In the case of the balance device, all of the electronics in the handheld part of the system might fit into a discreet mouthpiece. In the case of the BrainPort vision device, the electronics might be completely embedded in a pair of glasses along with a tiny camera and radio transmitter, and the mouthpiece would house a radio receiver to receive encoded signals from the glasses. It's not exactly a system on a chip, but give it 20 years -- we might be seeing a camera the size of a grain of rice embedded in people's foreheads.