[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 
University .

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 
information .

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 
state .

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 
fields .

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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