[Paleopsych] ANSA: Birth of consciousness in brain
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Mon Oct 10 23:59:36 UTC 2005
Birth of consciousness in brain
Rome, September 29 - Italian researchers have discovered the "birthplace" of
consciousness, a breakthrough that could eventually help cure a variety of
medical conditions .
While it has long been accepted that consciousness develops in a certain part
of the brain, Marcello Massimini and Giulio Tononi have located its precise
point of origin .
In a study to be published in the next issue of the international weekly
Science, the two experts claim that it is "formed" by rapid, mutual
communication between the upper, cortical areas of the brain. "We've known for
some time that certain areas of the brain are fundamental for generating
consciousness, while others are not," explained Massimini, who works at Milan
Together with Tononi, an Italian psychiatrist at the American University of
Wisconsin-Madison, he embarked on a series of experiments based on Tononi's
theory that consciousness is dependent on the brain's ability to integrate
In practical terms, this means that certain parts of the brain must be able to
"talk" to each other .
For example, individuals with injuries to the spinal chord or cerebellum do not
lose consciousness. On the other hand, damage to the outer part of the
thalamus, a central region in the brain, can induce a loss of consciousness
that is sometimes permanent, as in the case of comas .
In a bid to understand what goes on in the brain when people lose
consciousness, Tononi and Massimini looked at a reversible form of
unconsciousness: sleep "At the start of the night, when we fall into a deep
sleep, we and the universe around us 'cease to exist'," explained Massimini .
"Yet the paradoxical element is that while our consciousness vanishes, the
brain remains alert and very active." Using a new technique developed in
Finland, the pair proved that consciousness is lost during sleep owing to a
lack of communication between various different parts of the cerebral cortex .
They first applied continual, low-grade stimulation to awake, healthy
individuals in a very tiny section of the brain, using a technique known as
transcranial magnetic stimulation (TMS) .
The next stage involved measuring the spread of the stimulus with a
high-resolution electroencephalogram (hr-EEG). "The result was crystal clear
and absolutely extraordinary," said Massimini .
When the subjects were awake, the stimulus lasted as long as 300 milliseconds,
while it spread for just 100-150 milliseconds during deep sleep, showing that
the brain is incapable of transmitting stimuli to other sections while in this
This lack of connection between different cortical areas during sleep is vital
in explaining the transition from consciousness to unconsciousness, according
to Massimini .
The combination of TMS and hr-EEG could eventually be used to create a kind of
"index of consciousness", helping doctors make critical decisions in
controversial "vegetable" cases, he said .
While such developments are still some time in the future, he and Tononi
believe their discovery could have more immediate applications in a variety of
Testing has already started on schizophrenic subjects, in the hope it could
eventually help treat the condition, but it could also be used to evaluate
comas or even maintain closer checks on patients under anaesthesia, he said.
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