BRAIN-COMPUTER INTERFACE


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INTRODUCTION:

An implantable brain-computer
interface the size of an aspirin has been clinically
tested on humans by American company
Cyberkinetics. The
'BrainGate' device can provide paralysed or
motor-impaired patients a mode of
communication through the translation of
thought into direct computer control. The
technology driving this breakthrough in the
Brain-Machine-Interface field has a myriad of
potential applications, including the development
of human augmentation for military and
commercial purposes.


BRAINGATE—EMPOWERING THE HUMAN BRAIN:

The BrainGate System is used to sense, transmit,
analyze and apply the language of neurons. The
System consists of a sensor that is implanted on
the motor cortex of the brain and a device that
analyzes brain signals. This sensor consists of a
tiny chip (smaller than a baby aspirin) with
hundred electrode sensors-each thinner than a
hair- that detect brain cell electrical activity. The
principle of operation behind the BrainGate
System is that with intact brain function, brain
signals are generated even though they are not
sent to the arms, hands and legs. The signals are
interpreted and translated into cursor
movements, offering the user an alternate
“BrainGate pathway” to control a computer with
thought, just as individuals who have the ability
to move their hands use a mouse.


THE CONNECTOR:

When somebody thinks “move cursor
up and left” his cortical neurons fire in a
distinctive pattern; the signal is transmitted
through the pedestal plug attached to the skull.



BCI versus Neuroprosthetics:

Neuroprosthetics is an area of
neuroscience concerned with neural prosthesesusing
artificial devices to replace the function of
impaired nervous systems or sensory organs. The
most widely used neuroprosthetic device is the
cochlear implant, which was implanted in
approximately 70,000 people world wide as of
2005 according to the statistics conducted. There
are also several neuroprosthetic devices that aim
to restore vision, including retinal implants, optic
nerve cuffs and implants directly into the visual
cortex.



Human BCI Interface:
Non-invasive BCIs:

As well as invasive experiments (see
below), there have also been experiments in
humans using non-invasive neuroimaging
technologies as interfaces.
Electroencephalography (EEG) is the most
studied potential human interface, mainly due to
its fine temporal resolution, ease of use,
portability and low set-up cost. However
practical use of EEG as a BCI requires a great
deal of user training and is highly susceptible to
noise. For example, in experiments beginning in
the mid-1990s, Niels Birbaumer of the
University of Tübingen in Germany used EEG
recordings of slow cortical potential to give
paralysed patients limited control over a
computer cursor. (Birbaumer had earlier trained
epileptics to prevent impending fits by
controlling this low voltage wave.) The
experiment saw ten patients trained to move a
computer cursor by controlling their brainwaves.
The process was slow, requiring more than an
hour for patients to write 100 characters with the
cursor, while training often took many months.