Advanced Neural Prosthetics: Prospects and Challenges
Gerwin Schalk, Ph.D.
In 1938, Herbert Jasper, a young Canadian neuroscientist, sent a Christmas card to Hans Berger, the
inventor of the electroencephalogram. In this card, brain waves emanate from Jasper's scalp and make up
Jasper's Christmas greetings to Hans Berger. In the 70 years since then, many science-fiction authors and
scientists have speculated that it may be possible to use signals recorded directly from the brain to
communicate messages to the outside world using a brain-computer interface (BCI).
The field of BCI research began to develop about 25 years ago and transformed from initial isolated
demonstrations by a few groups into a large scientific enterprise that is currently producing more than 100
peer-reviewed articles and several dedicated conferences and workshops each year. This level of
productivity is reflective of the large and continually growing enthusiasm by the scientific community,
funding agencies, and the public. BCI demonstrations described to date include four-dimensional control
of a robotic arm using implanted microelectrodes, three-dimensional control of a computer cursor using
scalp-recorded EEG, and spelling at a rate of more than 20 characters per minute using subdurally
recorded ECoG. At the same time, despite substantial increases in our understanding of nervous system
function, better mathematical approaches to interpret this function, and despite the pervasive availability
of cheap and powerful computers, BCI performance is still poor compared to conventional motor
performance, has in important aspects improved only marginally over the past 20 years, and we still have
only a very rudimentary understanding of the basic principles that produce and optimize BCI control.
Most importantly, despite recent encouraging developments, the field of BCI research has yet to produce
solid evidence that BCI systems can actually improve people's lives or provide other distinct advantages.
In this talk, I will review the underlying rationale for BCI research, the field's strong and growing
enthusiasm, the impressive demonstrations produced by the field, and the sobering reality of the
remaining substantial limitations. I then propose several reasons for these shortcomings, and provide
suggestions for future research directions that are implied by this analysis.