by Linda LIM
Imagine being able to communicate or control an object just by thinking about it. This may sound like the stuff of science fiction, but research advances are making it a reality.
rain cells communicate by producing tiny electrical
impulses that facilitate processes such as thought,
memory, consciousness, and emotion. Electroencephalography
(EEG), a process that involves placing multiple
electrodes on a person's scalp to capture neural signals, detects
these impulses as tiny currents. The acquired signals, when amplified
and input into a computer for processing, can be translated
into messages or commands that reflect a person's intentions and,
in essence, has led to brain-computer interface (BCI) research.
BCI, by definition, is a system that allows a person to
communicate with or control the external world without involving
the brain's normal output pathways. These pathways
comprise the specific nerves and muscles associated with such
human activity as speech or movement.
Current BCI researchers have done most of their research on
patients who are in a so-called locked-in state, such as those who
suffer from amyotrophic lateral sclerosis (ALS), in which motor-function
nerves in the spinal cord and brain progressively fail
until patients end up completely paralysed. Even though they
can no longer communicate their needs and feelings, they retain brain function.
Niels Birbaumer, a neuropsychologist at the University of
Tuebingen in Germany and a veteran researcher in BCI, has
pioneered and implemented a BCI system called the Thought
Translation Device (TTD) - a device that allows patients to use
their thoughts to control a word processor (Figure 1).
A patient using the TTD wears a cap that brings electrodes in
contact with his or her scalp. The TTD acquires slow cortical
potential (SCP) signals, a type of slow voltage change generated
in the cerebral cortex picked up by an EEG. With training, an ALS
patient can actually learn to generate the appropriate
SCP signals to control cursor movements on a notebook
computer running word-processing software as part of
the TTD device.
Figure 2 shows how the notebook screen appears
during the initial training phase. Patients first train
their thoughts to move a cursor into a top- or bottom-highlighted
screen goal. If they succeed, a smiley face appears with the message "very good" as positive
feedback. Birbaumer and his team do not teach patients
how to train their thoughts; they advise patients to watch
closely and adopt an approach that works for them.
Birbaumer explains: "Initial patient training requires
a team comprising a physicist, a neurologist, and a
psychologist concerned with patient learning. Patients may
become demotivated in the absence of results, and since the TTD
will only do what the patient wants it to do, sometimes we have
to adapt the TTD to each individual patient."
Once patients become sufficiently accurate at this game, they
proceed to train on word processor software called the Language
Support Program (LSP) in which letters for selection appear in a
bottom-located goal and selected letters appear in a top-located
goal (Figure 3).
Although it may take weeks or months before they learn to
control the TTD, ALS patients now have the opportunity to
communicate. Three of Birbaumer's patients have in fact learned
to write fluently with the TTD.
Birbaumer confides: "Our next goal is to develop a language
support system that is faster and easier to use. This will be useful
for the millions of patients who are paralysed from brainstem
stroke, ALS, or coma.
"To do so, we have to collaborate with people in fields as
diverse as neuroscience, psychology, neurology, information
processing, computing, and engineering. Interdisciplinary effort
is important in BCI research, and a lack of it is not uncommon.
Sometimes the neuroscience people separate from the
mathematicians or informatics experts."
Apart from the application in communication, another
potential use of BCI is as a neuroprosthesis for
the partially paralysed - "neuro" because only
thoughts are needed to operate a prosthesis.
Recently scientists have had success in making
a monkey operate a robotic arm via its thoughts.
BCI researchers are also interested in a wheelchair
for people with total paralysis, and it is in this
area that Birbaumer will be working with
scientists from the Institute for Infocomm
Research (I2R) in Singapore and the Department
of Mechanical Engineering at the National
University of Singapore. The joint research project
will be Asia's first-ever foray into BCI research.
The collaboration envisions an individual
controlling his brain blood flow through a BCI
system involving functional magnetic resonance
imaging in order to manipulate a wheelchair.
"Their ideas in using blood flow to develop a
wheelchair that you can run with your brain
are good," Birbaumer says, referring to the I2R
team's research focus.
"Aside from the usual constraints of time,
we are actually looking at a very doable task,
especially since the I2R team has good
computational competence in signal processing
and analysis, critical to BCI research."
For more information contact Niels Birbaumer at email@example.com
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