2003 Conference Proceedings

Go to previous article 
Go to next article 
Return to 2003 Table of Contents 


A REVOLUTIONARY APPROACH TO COMPUTER ACCESS: COHERENT DETECTED PERIODIC BRAINWAVE COMPUTER CONTROL

Presenter
Dr. Andrew M. Junker
Brain Actuated Technologies Inc.
Email: admin@brainfingers.com

SUMMARY

A method to achieve brainwave computer control independent of involuntary muscle activity at the forehead will be presented in lecture format, NIH grant HD42942-01.

INTRODUCTION

The field of Augmentative and Alternative Communication (AAC), though relatively young, has provided a means for many individuals to express themselves that was not available in the past. Alternative computer input devices are now available in a variety of options to support special needs communication and access to AAC (i.e., frontalis muscle switch, head and eye-tracking devices, chin switch, "sip and puff," voice activation, etc.). Use of this technology is, however, dependent on the user's ability to control their muscles.

There are individuals, who because of the severity of their physical limitations have been unable to access AAC technology through direct selection or scanning via a switch. These individuals often have disabilities related to cerebral palsy (CP), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), muscular dystrophy (MD), or traumatic brain injury (TBI). In many of these cases, the disability results in uncontrolled body activity that prevents the individual from achieving any form of consistent muscle control.

Other practical barriers to muscle-based systems involve physical fatigue associated with use, length and intensity of required system calibration and adjustment, length and intensity of required user training, and expense. Also, repetitive stress injuries have forced some users of muscle-control devices such as mouth sticks to give up these methods as a result of repetitive strain. Because of the access difficulties, communication for these individuals is often limited, left to interpretations by communication partners, or non-existent. Given the growth and advances in AAC technology that are taking place, a viable alternative access is the only factor standing between individuals with the most severe disabilities and the technology available to provide independent communication.

A viable alternative access must rely on a form of communication for the individual that is resistant to unrelated and involuntary body activity of the individual, and to random brainwave activity. An access system that utilizes some form of brainwave control is needed.

An access system that relies on brainwave signals derived from the forehead has excellent potential for satisfying all of the above requirements. It is easy to connect sensors to the forehead, as minimum site preparation is required. Brainwave signals can be detected at the forehead in addition to the subtle muscle activity that is found there. By using a coherent phase detection method it is hypothesized that it will be possible to feed back to the individual their periodic brainwave signals resulting from their desired input generation efforts independent of their unwanted inputs due to involuntary muscle activity. It is also hypothesized that the presence of elements of the subtle facial muscle signals will facilitate the learning of brainwave resonance control by acting as a sort of training wheels to guide the user to the sensation of periodic brainwave resonance.

Coherent amplitude detection will be evaluated. A system based on coherent amplitude detection is very similar to a variety of non-coherent spectral detection systems, except with much superior ability to reject interference from random brainwave activity and from muscle signals.

A communication system based on the frequency modulation (FM) of brainwaves is extremely attractive for people with significant spasticity, and quite attractive for anyone with neural-motor limitations because:

Both systems have a far superior ability to reject random bursts of noise such as are generated by spastic muscle movements in subjects with severe cerebral palsy. Coherent detection systems have the same advantage over a non-coherent amplitude modulation (AM) brainwave system that a commercial radio FM system has over AM radio.

APPROACH

The basic technical approach is to employ coherent detection of periodic brain waves, taking advantage of the ability of a coherent detection system to reject interference from muscle and random brainwave signals. The hands-free Cyberlink computer control system is used as the basic building block. Software will be modified to operate with full coherent detection. Twenty participants with severe muscle control disabilities will be used to answer the following questions: (i) can participants be trained to generate periodic signals; (ii) is the signal-to-noise ratio of these periodic signals sufficient to allow reliable two-level decisions; (iii) can participants be trained to control either the amplitude or frequency of these periodic signals and (iv) can the conscious blending of non-coherent signals enhance learning periodic signal generation.

RESULTS

The coherent detection system will be presented, demonstrated and explained. Results of the participants using the coherent detection system will be presented.


Go to previous article 
Go to next article 
Return to 2003 Table of Contents 
Return to Table of Proceedings


Reprinted with author(s) permission. Author(s) retain copyright.