Study on self awareness - just for information.
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student13
<pairamblr@gmail.com>Nov 7, 2009, 8:26:45 PM11/7/09
to Atheism vs Christianity
http://sciencenow.sciencemag.org/cgi/content/full/2009/1102/2?etoc
=================================================
Feeling the beat. A study of a man with extensive brain damage
(bottom) suggests that changes in heartbeat are normally detected via
the insula as well as the sense of touch
Credit: Sahib S. Khalsa and David Rudrauf
Brain Damaged But Self-Aware
By Greg Miller
ScienceNOW Daily News
2 November 2009
"I think, therefore I am," pronounced the famed French philosopher
René Descartes. What imbues us with this uniquely human sense of self-
awareness? Some neuroscientists have pegged an area of the brain known
as the insula, which helps us detect what's going on within our
bodies. But an unusual case of a man with extensive damage to this
region suggests that the insula cannot be the sole source of self-
awareness.
Tucked deep inside the brain, the insula responds to pain, a full
stomach, changes in body temperature, and other internal sensations.
Researchers have proposed that the insula somehow translates these
visceral sensations into conscious, subjective experience. But it's a
hard hypothesis to test.
Enter "Roger." In 1980, a viral disease known as herpes simplex
encephalitis destroyed 25% to 35% of his brain, including nearly all
of his insula. Yet Roger functions remarkably well: Although he
suffers from amnesia and has lost his sense of smell and taste, he has
a normal IQ and very good language skills.
Roger doesn't act like he lacks self-awareness, but researchers led by
Sahib Khalsa and David Rudrauf of the University of Iowa in Iowa City
were curious about his ability to detect visceral sensations. To
investigate, they gave Roger a drug that increases heart rate. Then
they asked him to turn a dial to indicate any changes he noticed.
Roger detected the increase, as did 11 healthy volunteers.
Khalsa, who is now at the University of California, Los Angeles,
suspected that Roger's brain might be getting some help from sensory
receptors in the skin capable of detecting a suddenly pounding heart
and relaying that information to somatosensory regions of the brain.
So Khalsa repeated the experiment, after applying an anesthetic cream
to Roger's chest to deaden the sensory receptors. Now, when Roger got
the drug, his dial didn't budge. In contrast, the other subjects given
the same treatment still detected the change in heart rate.
The researchers conclude that parallel pathways in the brain--one
involving the insula, the other involving the sense of touch--mediate
the ability to feel the heartbeat. The findings, reported online this
week in Nature Neuroscience, undermine the hypothesis that the insula
is the sole source of self-awareness in the human brain, Khalsa says.
Not everyone agrees with that interpretation. Bud Craig, a
neuroscientist at the Barrow Neurological Institute in Phoenix,
Arizona, who has been a major proponent of the idea that the insula
has a crucial role in self-awareness, thinks the authors' conclusions
are deeply flawed. He points out that Roger does have some residual
tissue left in his left insula, which Craig thinks explains his
apparent self-awareness. Craig also argues that the pathway that
detects a pounding heart via the skin is fundamentally different from
the visceral sensations he and others have argued are translated into
conscious experience by the insula.
Others offer a more upbeat assessment. "The experiment is very
clever," says neuroscientist Antoine Bechara of the University of
Southern California in Los Angeles. (Bechara has previously
collaborated with the Iowa group but was not associated with the
current study.) One possibility that the researchers did not test, he
adds, is that the somatosensory system and the insula convey different
aspects of the experience of a quickening heart rate: The
somatosensory system simply reports the facts (e.g., "My heart is
beating faster"), whereas the insula generates a subjective feeling of
discomfort or anxiety. And that is similar to the argument Craig has
been making all along.
=================================================
Feeling the beat. A study of a man with extensive brain damage
(bottom) suggests that changes in heartbeat are normally detected via
the insula as well as the sense of touch
Credit: Sahib S. Khalsa and David Rudrauf
Brain Damaged But Self-Aware
By Greg Miller
ScienceNOW Daily News
2 November 2009
"I think, therefore I am," pronounced the famed French philosopher
René Descartes. What imbues us with this uniquely human sense of self-
awareness? Some neuroscientists have pegged an area of the brain known
as the insula, which helps us detect what's going on within our
bodies. But an unusual case of a man with extensive damage to this
region suggests that the insula cannot be the sole source of self-
awareness.
Tucked deep inside the brain, the insula responds to pain, a full
stomach, changes in body temperature, and other internal sensations.
Researchers have proposed that the insula somehow translates these
visceral sensations into conscious, subjective experience. But it's a
hard hypothesis to test.
Enter "Roger." In 1980, a viral disease known as herpes simplex
encephalitis destroyed 25% to 35% of his brain, including nearly all
of his insula. Yet Roger functions remarkably well: Although he
suffers from amnesia and has lost his sense of smell and taste, he has
a normal IQ and very good language skills.
Roger doesn't act like he lacks self-awareness, but researchers led by
Sahib Khalsa and David Rudrauf of the University of Iowa in Iowa City
were curious about his ability to detect visceral sensations. To
investigate, they gave Roger a drug that increases heart rate. Then
they asked him to turn a dial to indicate any changes he noticed.
Roger detected the increase, as did 11 healthy volunteers.
Khalsa, who is now at the University of California, Los Angeles,
suspected that Roger's brain might be getting some help from sensory
receptors in the skin capable of detecting a suddenly pounding heart
and relaying that information to somatosensory regions of the brain.
So Khalsa repeated the experiment, after applying an anesthetic cream
to Roger's chest to deaden the sensory receptors. Now, when Roger got
the drug, his dial didn't budge. In contrast, the other subjects given
the same treatment still detected the change in heart rate.
The researchers conclude that parallel pathways in the brain--one
involving the insula, the other involving the sense of touch--mediate
the ability to feel the heartbeat. The findings, reported online this
week in Nature Neuroscience, undermine the hypothesis that the insula
is the sole source of self-awareness in the human brain, Khalsa says.
Not everyone agrees with that interpretation. Bud Craig, a
neuroscientist at the Barrow Neurological Institute in Phoenix,
Arizona, who has been a major proponent of the idea that the insula
has a crucial role in self-awareness, thinks the authors' conclusions
are deeply flawed. He points out that Roger does have some residual
tissue left in his left insula, which Craig thinks explains his
apparent self-awareness. Craig also argues that the pathway that
detects a pounding heart via the skin is fundamentally different from
the visceral sensations he and others have argued are translated into
conscious experience by the insula.
Others offer a more upbeat assessment. "The experiment is very
clever," says neuroscientist Antoine Bechara of the University of
Southern California in Los Angeles. (Bechara has previously
collaborated with the Iowa group but was not associated with the
current study.) One possibility that the researchers did not test, he
adds, is that the somatosensory system and the insula convey different
aspects of the experience of a quickening heart rate: The
somatosensory system simply reports the facts (e.g., "My heart is
beating faster"), whereas the insula generates a subjective feeling of
discomfort or anxiety. And that is similar to the argument Craig has
been making all along.
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