-Caveat Lector-
Thursday May 24 2:24 PM ET
New Study Pinpoints Source of Impulsive Behavior
By Katherine Hunt
WASHINGTON (Reuters) - Trying to choose between a cookie or a
carrot
at snack time?
A newly identified ``hot spot'' on the brain may be the key to
impulsive
behavior, involved in the critical choice between instant
gratification and
delayed reward, researchers said on Thursday.
In a study reported in the journal Science, researchers examined
the
nucleus accumbens, located at the base of the forebrain. The
region
responds to natural rewards such as food and sex, as well as
drugs such
as amphetamines and cocaine, through their effects on the
neurotransmitter chemical dopamine.
``We have shown that damage or dysfunction of the nucleus
accumbens
can cause, without a doubt, impulsive choice,'' said study author
Rudolf
Cardinal, of the Department of Experimental Psychology in
Britain's
University of Cambridge.
The findings have implications for the treatment and
understanding of drug
addiction, attention deficit/hyperactivity disorder (ADHD) and
anti-social
behavior, all of which are linked to the impulse for instant
gratification.
The researchers trained rats to choose between a small immediate
reward
and a larger, delayed reward. In tests after their nucleus
accumbens were
damaged, the researchers found the rats tended to choose the
instant
gratification of the small reward, rather than the larger reward
delivered
after a delay.
``We already knew that there was a correlation between
abnormalities in
the nucleus accumbens and impulsive behavior,'' Cardinal said.
``Now we
have clear evidence that such abnormalities can cause this
behavior.''
Lesions on two other regions of the brain that send information
to the
nucleus accumbens, the anterior cingulate cortex and medial
prefrontal
cortex, did not cause the rats to act impulsively, the study
found.
The findings ``suggest the nucleus accumbens core, at least for
impulsive
choice, is a critical region,'' Cardinal said.
The research also sheds new light on drugs like Ritalin (news -
web sites),
used to treat ADHD by affecting the dopamine systems in the
brain.
``Our research suggests that (Ritalin's) actions in the nucleus
accumbens
may responsible for its beneficial affects on impulsive
behavior,'' he said.
A SMOKER'S CHOICE
Like most discoveries, the study has triggered more questions.
``I think it's an interesting question to ask, why were the
animals with
nucleus accumbens lesions impulsive?'' Cardinal said. ``Were they
impulsive because they were less sure that in fact, delayed
reward was
coming?''
The cigarette smoker's choice is a good analogy, he said, and
further
research is needed to determine what is going on, he said.
The choice is cigarettes now or avoiding lung cancer later, he
said. So
does the smoker really believe that cigarettes cause lung cancer?
Or
maybe the smoker believes cigarettes cause cancer but cares less
about
long-term health than the instant buzz.
``That's one question about the underlying psychology,'' Cardinal
said. ``Do
you make your impulsive choices in the full knowledge of what you
are
getting yourself into? Or do you lack insight into the
consequences?''
=======================================================
Kadosh, Kadosh, Kadosh, YHVH, TZEVAOT
FROM THE DESK OF:
*Michael Spitzer* <[EMAIL PROTECTED]>
The Best Way To Destroy Enemies Is To Change Them To Friends
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