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Last Updated: Apr 21st, 2008 - 09:32:59 |
GOOD TECHNOLOGY
One of the most difficult aspects of some more severe disabilities is a lack of communication ability. Individuals who have had significant injuries, those with ALS, brainstem strokes or various neuromuscular disorders can become what is termed “locked in”. In a book entitled “The Diving-Bell and the Butterfly, Jean-Dominique Bauby describes his experience as a locked in patient as “Paralyzed from head to toe, the patient is imprisoned inside his own body, his mind intact but unable to speak or move”.
BCI, which stands for Brain-computer interface offers hope of those individuals facing a “locked in” situation. It allows the user to communicate with others without having to use voluntary muscle activity. It does this by interpreting manifestations of brain activity using an EEG. The BCI uses what is known about electrical brain activity to make a “smart guess” as to the message the user has chosen to communicate.
There are two types of EEG-BCIs that are currently being tested worldwide. The first is based on evidence that through a biofeedback learning process, individuals can acquire the ability to control the spectrum of their own electrical brain activity. It is through the detection of the subject controlled changes in brain activity through the use of the EEG that the BCI system can infer the user’s choices. It provides the user voluntary control over a “joystick”. The disadvantage is that it takes a great deal of prior training in order for this system to be functional. The second type relies on the findings that the brain reacts differently to different stimuli. This system emulates a keyboard rather than a joystick, allowing the user to choose from a finite number of options; the keys on a keyboard. One such system is called the P300-based Speller. It relies on a brain response known as the P300, which has been studied since 1965 and is well documented. It requires a computer, amplifier, electrode application system and a monitor. The user display is a matrix that can be varied in size according to the individual’s preferences and ability. The matrix may present letters, numbers, words, sentences, pictures or other symbols. The system implements what is termed an “oddball paradigm” in which the row and column containing the chosen cell of the matrix are the only items that will elicit a P300 brain response. The rows and columns of the matrix are illuminated in a random sequence and the EEG elicited by each of them is examined. By recognizing online and in real time which tow and column elicited a P300, the system can identify which character the subject chose to “type”. Studies have shown that a user of this system can communicate at the rate of eight characters per minute. While this may seem slow, it is a huge improvement over no communication ability at all.
FUNCTIONALITY
This technology is being used most frequently with sufferers of ALS or Lou Gehrig’s disease. This is a rapidly progressive and invariably fatal neurological disease that attacks the neurons that control voluntary muscles. At present, 56oo people per year are diagnosed with ALS in the U.S. The vast majority of these individuals remains cognitively intact but suffers progressive deterioration of the body.
The P-300 BCI has been made into a portable unit. Using the portable version a user can control a 9” x8” matrix combined with software that augments the functionality of the unit and allows the user full control of all Windows and Office 2003 programs.
Obviously the technology needed for devices such as these is evolving. As the technology improves and the portability of the devices becomes more and more user friendly, then perhaps the communication difficulties of people with neuromuscular diseases can be minimized. Studies are currently taking place across North America and in Europe to evaluate the breadth and quality of assistance devices such as these offer their users.
For more information about other assistive communication devices you can visit the American Speech and Hearing Website at ASHA.org.
Quotation of the Week
"To use the same words is not a sufficient guarantee of understanding; one must use the same words for the same genus of inward experience; ultimately one must have one's experiences in common."
Friedrich Wilhelm Nietzsche,
Beyond Good and Evil)
Comments? Trish-blair@redwoods.edu
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