Impulsive? Blame Brain's Instant
Gratification Hot Spot
http://www.msnbc.com/news/./577804.asp?0na=223R3h0-
5-24-1
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 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
ingulate 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 criticalregion,"
Cardinal said.
The research also sheds new light on drugs like
Ritalin, 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?"
� 2001 Reuters Limited. All rights reserved.
Republication or redistribution of Reuters content is
expressly prohibited without the prior written consent
of Reuters.
[Image]
MainPage
http://www.rense.com
This Site Served by TheHostPros
Dept of Psychology
University of Manitoba
Winnipeg, MB Canada
"Our situation on this Earth seems strange. Every one of us appears here involuntarily,
and uninvited, for a short stay without knowing why. To me it is enough to wonder at the secrets."
-- Albert Einstein
"Men are probably nearer the central truth in their superstitions than in
their science." --Henry David Thoreau
