edit 02192007
since i just finished neuroanatomy - this is particularly interesting:
(stolen from
lfespock)
Loving with all your ... brain
By Elizabeth Cohen
CNN Medical Correspondent
(CNN) -- Close your eyes for a minute and envision all the romantic parts of the human body.
Her beautiful eyes. His strong shoulders. We'll stop there, but you go right ahead and think about all the body parts you want.
Bet you didn't think about the caudate and the ventral tegmental areas, did you?
These
areas of the brain, while little known to most people, are helping
scientists explain the physiological reasons behind why we feel what we
feel when we fall in love.
By studying MRI brain scans of
people newly in love, scientists are learning a lot about the science
of love: Why love is so powerful, and why being rejected is so horribly
painful.
In a group of experiments, Dr. Lucy Brown, a professor
in the department of neurology and neuroscience at the Albert Einstein
College of Medicine in New York, and her colleagues did MRI brain scans
on college students who were in the throes of new love.
While
being scanned, the students looked at a photo of their beloved. The
scientists found that the caudate area of the brain -- which is
involved in cravings -- became very active. Another area that lit up:
the ventral tegmental, which produces dopamine, a powerful
neurotransmitter that affects pleasure and motivation.
Dr.
Brown said scientists believe that when you fall in love, the ventral
tegmental floods the caudate with dopamine. The caudate then sends
signals for more dopamine.
"The more dopamine you get, the more of a high you feel," Dr. Brown says.
Or
as her colleague, Dr. Helen Fisher put it: When you fall in love,
"exactly the same system becomes active as when you take cocaine. You
can feel intense elation when you're in love. You can feel intense
elation when you're high on cocaine."
Is it love -- or sex?
Scientists
then wondered: Does a brain in love look much like a sexually
stimulated brain? After all, we associate love and sex and sometimes
confuse them.
The answer is: Brains in love and brains in lust don't look too much alike.
In
studies when researchers showed erotic photos to people as they
underwent brain scans, they found activity in the hypothalamus and
amygdala areas of the brain. The hypothalamus controls drives like
hunger and thirst and the amygdala handles arousal, among other things.
In
the studies of people in love, "we didn't find activity in either,"
according to Dr. Fisher, an anthropologist and author of "Why We Love
-- the Nature and Chemistry of Romantic Love."
"We now have physiological data that suggests there are different brain systems for sex and love," says Dr. Fisher.
At
some point, the two do become linked. People in love have elevated
levels of dopamine. Lots of dopamine, in turn, triggers the production
of testosterone, which is responsible for the sex drive in both men and
women.
This helps explain why falling in love can make someone all of a sudden seem sexy.
"Three weeks ago he was just another nice guy in the office and now everything about him is sexual," says Dr. Fisher.
All
this research into sex and love got the researchers thinking: Most
other mammals don't have this drive for romantic love and attachment.
Why do humans have it? After all, we could easily propagate the species
just with our sexual urges.
Dr. Fisher thinks it has a lot to do with how difficult it once was to raise children.
"Go
back millions of years to the grasslands of Africa. A woman was
carrying the equivalent of a 20-pound bowling ball in one arm, and
sticks and rocks in another arm to protect herself in this dangerous
environment. She needed a partner to help her. She couldn't do it
alone," Dr. Fisher says.
And even today, when we have strollers
and the environment isn't quite as dangerous, having a mate still
helps. "There are women who raise a baby by themselves, but it's a lot
harder," she says.
Male brain - female brain
In their work with the lovestruck, the scientists found brain differences between men and women.
"The
men had quite a bit more activity in the brain region that integrates
visual stimuli. This isn't surprising considering that men support the
porn industry and women spend their lives trying to look good for men,"
says Dr. Fisher.
But she adds there's probably a more
anthropological reason at work. Simply put: A man's evolutionary
mission is to spread his seed. That won't work if he mates with an
80-year-old grandmother.
"Men have to be able to size up a woman visually to see if she can bear babies," says Dr. Fisher.
The women's brain activities were a bit more puzzling.
The
scientists found that women in love had more activity than men in the
areas of the brain that govern memories. Dr. Fisher theorizes that this
is a "female mechanism for mate choice." There are no visual clues for
whether a man is fertile, but if a woman really studies a man and
remembers things about his behavior, she can try to determine whether
he'd make a reliable mate and father.
Thus, if it sometimes
seems like a woman remembers everything -- good and bad -- about a man,
"it's not just her being picky. It's an old Darwinian evolutionary
strategy."
What's love got to do with it?
In
the end, Drs. Fisher and Brown say what they learned from lovers'
brains is that romantic love isn't really an emotion -- it's a drive
that's based deep within our brains, right alongside our urges to find
food and water.
"This helps explain why we do crazy things for
love," says Dr. Brown. "Why did Edward VIII give up the throne for
Wallis Simpson? The systems that are built into us to find food and
water are the things that were also active when he renounced the throne
of England."
Now their research is centered on the flip side of
love. They've recruited college students who'd just been rejected by
their sweethearts. Again, the scientists performed MRI's while these
students looked at photos of the objects of their affection.
This
time, the results were different, Dr. Brown says. The insular cortex,
the part of the brain that experiences physical pain, became very
active.
"People came out of the machine crying," she said. "We won't be doing that experiment again for a long time."
Elizabeth Cohen is a correspondent with CNN Medical News. Producer Amy Burkholder contributed to this report.
