Scientists Explore Consciousness
- Scientists Explore Consciousness
New results published in the Proceedings
of the National Academy of Sciences.
An international team of scientists
led by a University of Leicester researcher
has carried out a scientific study into the
realm of consciousness.
The scientists have made a significant
step into the understanding of conscious
perception, by showing how single neurons in the human
brain reacted to perceived and nonperceived images.
University of Leicester bioengineer Dr Rodrigo
Quian Quiroga is spearheading this study
which is opening new possibilities of exploring
a hitherto relatively unchartered scientific area.
The team have today (MONDAY FEB 18) published
a paper in an international journal, the
Proceedings of the National Academy of Sciences
(PNAS) revealing new discoveries in the field
of consciousness studies.
Dr Quian Quiroga said: "There has been much
interest in recent years in consciousness,
which is considered by many as one of the major
scientific challenges to be solved, or at least
addressed in a scientific -rather than
ust philosophical- way.
"In fact, there are a few centres, journals
and conferences dedicated to this topic. The problem
with consciousness is that it is very hard to be
defined and it implicates too many different things.
For this reason, several researchers started
to specify more clearly what they mean by
consciousness (even if this is a limited view of
the whole issue) and think about ways to study
it in a scientific way. This approach was championed
by the late Francis Crick and my former supervisor
at Caltech, Christof Koch.
"Following this line, the paper in PNAS asks
how the activity of single neurons in the human
brain can reflect conscious perception.
"Recordings were done in epileptic patients
candidates of curative surgery in which
intracranial electrodes are implanted to
establish the location of the epileptic
focus and evaluate the potential outcome
of the surgery. Patients usually stay for
1 or 2 weeks in the guard and this gives us the
extraordinary opportunity to perform experiments
and study how neurons in the human brain
respond to different perceptual and behavioural tasks.
"In this particular study we showed pictures
in a computer screen very briefly,
at the threshold of conscious recognition.
Subjects had to report whether they
recognized or not the particular picture showed
in each trial. The key point is
that, since the pictures are shown very briefly,
for exactly the same visual input sometimes the
subjects reported recognizing the picture and sometimes
not recognizing it. Then we could ask
whether the neurons fire according to
the subjects' conscious perception or the
actual visual inputs.
"We found that the neurons we recorded
responded to the conscious perception in an
"all-or-none" way by dramatically changing their firing
rate only when the pictures were recognized.
"For example, a neuron in the hippocampus
of one patient fired very strongly to a picture
of the patient's brother when recognized and remained
completely silent when it was not, another
neuron behaved in the same manner with pictures
of the World Trade Centre, etc.
"Interestingly, based on the firing of these
neurons it was possible to
predict far above chance whether a picture
was recognized or not. Another
interesting observation is that a picture
flashed very briefly generated nearly
the same response -if recognized- as when
shown for much longer periods
of time. This means that a single snapshot
as brief as 33 ms was sufficient
to trigger strong neuronal responses far
outlasting the stimulus presentation,
signaling the conscious perception of the
Dr Quian Quiroga said the study had important
implications. Potential applications of
this discovery include the development of Neural Prosthetic
devices to be used by paralysed patients
or amputees. A patient with a
lesion in the spinal cord (as with the
late Christopher Reeves), can still think
about reaching a cup of tea with his arm,
but this order is not transmitted to
The idea of Neural Prostheses is to read
these commands directly from the
brain and transmit them to bionic devices
such as a robotic arm that the
patient could control directly from
Dr Quian Quiroga's work showing that it
is possible to read signals from the
brain is a good step forward in this
direction. But there are still clinical and
ethical issues that have to be resolved
before Neural Prosthetic devices can
be applied in humans.
In particular, these would involve invasive
surgery, which would have to be justified
by a clear improvement for the patient
before it could be undertaken.
Dr Quian Quiroga's discovery has far-reaching
implications not only for the development of
neuronal prostheses, but for treatment of patients
with pathologies involving the hippocampal
formation, such as epilepsy, Alzheimers and
schizophrenia and for further understanding of how
perceptions and memories are represented in the brain.
- Dear J,Since when I read this condition of yours somehow you
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Then what do I give to you?
Please go to "google alert".Fill in "human neuroplasticity". You
will get every information on human neuroplasticity in your E-mail
ID. Some are trash. Some are just commercial. But you will get great
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> "this is an interesting thread.in
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