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Oddball
Science Helps "Locked In" People Communicate
http://www.newswise.com/articles/view/513597/
Newswise —
University of South Florida psychologist Emanuel Donchin and his students
are perfecting ways to help people who are paralyzed yet fully conscious -
with intact cognitive systems - communicate via a brain computer interface (BCI).
Although the patient is unable to communicate, the electrical activity in
their brains is normal. Through the BCI it becomes possible for users to
“type” on a “virtual keyboard” using their brain waves.
The BCI,
says Donchin, can help patients who suffer from amyotrophic lateral
sclerosis (ALS, or Lou Gehrig’s disease) - a rare progressive neurological
disorder that ultimately leads to a complete paralysis of voluntary muscles
in all parts of the body; cerebral palsy; or patients “locked in” following
a brain stem stroke.
“In
essence, we are trying to provide the brain with new channels for
communication and control by capturing and analyzing the electrical or
electroencephalographic (EEG) activity produced in the brain,” he explained.
“Our goal is to restore communication functions.”
To create
an assistive “mental prosthesis,” Donchin’s extensive work is focused on
capturing and reporting unique brain activity that occurs upon the visual
observation of a rare or “oddball” event. According to Donchin, the “oddball
paradigm” relies on a response to deviant stimuli embedded in a series of
standard stimuli, such as letters, symbols and commands flashing randomly on
a keyboard-like screen. By analyzing the electrical activity as
event-related brain potential (ERP) generated by the oddball event, the user
in Donchin’s studies focuses attention on the character to be communicated
as elements of the display are flashed on the screen.
“The
chosen character is the one eliciting a ‘P300,’” said Donchin. “Thus, by
detecting which rows and columns in the display elicit a P300 the computer
can determine the character the patient is trying to ‘type.’”
In
collaboration with the Wadsworth Institute at SUNY-Albany, Donchin’s group
has conducted numerous studies with healthy and disabled volunteers who,
wearing electrodes on their scalp attaching them to the BCI, were placed in
front of an electronic screen display of 26 letters of the alphabet and
other symbols and commands in a six-by-six row and columns flashing in
random sequence. Test subjects were able to “operate” a virtual keyboard
when their EEG reactions to oddball events in the random flashing were
analyzed. Researchers found greater electrical response in the rarely
presented, or oddball, stimuli and the spike in the subjects’ EEG at time of
the oddball event created a means of communication.
“Ideally,
the subject can spell out a message by successively choosing among the 26
letters,” explained Donchin. “We are examining the operating characteristics
of this communication channel and analyzing the speed with which there was
an EEG focus on the letter of interest.”
Test
subjects were able to communicate their choice of a letter at the rate of
about one character every 26 seconds.
“This is,
of course, a slow rate of communication,” said Donchin. “But, considering
there is no other channel of communication, even this slow rate is welcome.”
Since
coming to USF, Donchin with his student Eric Sellers tested more than 15 ALS
patients and have established that, in general, the system works although
many adjustments in the procedure are required to allow the use of the BCI
in patients’ homes.
- Paralyzed
patients use brain waves to talk
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http://www.nlm.nih.gov/medlineplus/news/fullstory_12033.html
- A German
researcher Tuesday described a new technique
in
which paralyzed patients can use their brain waves to
communicate with loved ones and caregivers. The technique,
which allows patients to spell out words on a computer screen, works well,
but only as long as patients learn to use it before they become completely
paralyzed, University of Tubingen psychology professor Niels Birbaumer
told United Press International.
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- If a person cannot move, talk, or even blink, is it possible to
communicate with his brain?
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http://www.indiana.edu/~teleweb/cyberia/lockbrain.html
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- Brain-Computer Communication and Slow
Cortical Potentials
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http://ida.first.fhg.de/publications/HinSchNeuMelBlaCurBir04.pdf
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Abstract—
A Thought-Translation-Device (TTD) has been
designed to enable direct brain-computer communication using self
regulation of slow cortical potentials (SCPs). However, accuracy of SCP
control reveals high inter-subject variability. To guarantee the highest
possible communication speed, some important aspects of training SCPs are
discussed. A baseline correction of SCPs can increase performance.
Multi-channel recordings show that SCPs are of highest amplitude around
the vertex electrode used for feedback but in some subjects more global
distributions were observed. A new method for control of eye movement are
presented. Sequential effects of trial-to-trial interaction may also cause
difficulties to the user. Finally, psychophysiological factors determining
SCP-communication are discussed.
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- The
thought translation device: a neurophysiological approach to communication
in total motor paralysis.
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http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9928845&dopt=Abstract
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Self-initiation of EEG-based communication in paralyzed patients.
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http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11222979&dopt=Abstract
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- Biological feedback of brain and muscle activity: basic mechanisms
and clinical applications (Niels Birbaumer's facility)
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http://www.uni-tuebingen.de/medizinischepsychologie/projekte/biofeedb.htm
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- Predictors of successful self control during brain-computer
communication
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http://jnnp.bmjjournals.com/cgi/content/full/74/8/1117
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- A non-invasive communication device for the paralyzed.
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http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11932820&dopt=Abstract
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- Timing of EEG-based cursor control.
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http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9458060&dopt=Abstract
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- Mind-reading machines close communication gap
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http://www.int.iol.co.za/index.php?click_id=117&art_id=iol1049798661796B651&set_id=1
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- Using human extra-cortical local field potentials to control a
switch*
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http://www.iop.org/EJ/abstract/1741-2552/1/2/002
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- EEG Signal Classification for Brain
Computer Interface Applications
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http://bci.epfl.ch/publications/baztarricadiplomaproject.pdf
DVD available from Futurehealth.org $95 WZ4
Niels Birbaumer Slow
Cortical Potential biofeedback-- A new form of neurofeedback, with a
long history of research support
Institute of Medical Psychology and Behavioral
Neurobiology University of Tuebingen
This very different approach to training the brain
is not used in the US, yet it has extensive
research support, mostly done in Europe. Dr. Birbaumer, awarded the honor of
the most respected scientist in Europe, has developed an approach which
promises to add important new tools, dimensions and applications to the
armamentarium of the neurofeedback practitioner.
Slow cortical potentials indicate a state of
excitation or inhibition of large cortical neuron pools. Negative slow
brain potentials of several seconds duration indicate depolarization of the
underlying cortical network, positivity reflects reduction of fascilitation.
In several papers biofeedback of slow cortical potentials in normal
populations where described (Birbaumer et al 1990, Physiological Reviews)
which showed that self-produced negativity improves those behavioral and
cognitive activities which utilize mobilization of cortical networks.
Response speed, vigilance and concentration is increased during negativity,
positivity reduces mobilization. Cholinergic inflow to the cortical mantle
seems to be responsible for negativity, while positivity depends on the
activation of GABAergic inhibitory synapses. Measurement of brain blood flow
with functional MRI during biofeedback of slow cortical potentials (Birbaumer
et al, in press) demonstrates that during self-produced negativity
prefrontal thalamic and parietal structures are activated while during
self-induced positivity those structures are inhibited. Therefore it can be
concluded that self-regulation of slow cortical potentials involves
excitation and inhibition of attentional systems in cortical and subcortical
structures.
Biofeedback of slow cortical potentials was first
applied to the treatment of epilepsy, particular temporal lobe epilepsy
(Rockstroh et al 1989).
Several controlled studies have shown that training
of positivity for more than 40 sessions improves seizure frequency and
neuropsychological functions in temporal lobe epilepsy: three studies with
60 patients have demonstrated that after extended training of positivity one
third of patients is seizure-free, one third shows significant improvement
and one third does not respond. All patients were drug-refractory epileptic
patients with more than one seizure a week. These studies will be reviewed
and new data will be added.
Another successful application of slow brain
potential biofeedback is a brain-computer-interface communication system for
locked-in patients.
Locked-in-patients have no means to communicate
because all muscles including face muscles are paralyzed. Most of the
patients in our studies are patients with amyotrophic lateral sklerosis, a
neurological disease which leads to complete motor paralysis while all
sensory systems remain intact. Patients are artificially ventilated and have
to be fed artificially. These patients learn to produce cortical negativity
and positivity at different locations of the brain and use this brain
response to select in a special computer program verbal communication
subprograms by which a more or less fluent verbal communication through the
brain with the help of the computer becomes possible. Video demonstrations
and results of these studies will be presented at the conference. A new
successful application of slow brain potential biofeedback is the training
of left temporal negativity in aphasic patients. Already after 5 training
sessions improvement in expression and processing of words can be shown.
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