### <http://www.medicalnewstoday.com/medicalnews.php?newsid=54243&nfid=rssfeeds> 

### Brain-Mapping, Psychological Studies Support Mechanism For Compromised Control In Drug Addiction

Main Category: [Alcohol / Addiction / Illegal Drugs
News](http://www.medicalnewstoday.com/sections/alcohol/)\
Article Date: 18 Oct 2006 - 12:00pm (PST); in Medical News Today

![](media/image1.png){width="1.0416666666666666e-2in"
height="0.20833333333333334in"}People addicted to cocaine have an
impaired ability to perceive rewards and exercise control due to
disruptions in the brain\'s reward and control circuits, according to a
series of brain-mapping studies and neuropsychological tests conducted
at the U.S. Department of Energy\'s Brookhaven National Laboratory.\
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\"Our findings provide the first evidence that the brain\'s threshold
for responding to monetary rewards is modified in drug-addicted people,
and is directly linked to changes in the responsiveness of the
prefrontal cortex, a part of the brain essential for monitoring and
controlling behavior,\" said Rita Goldstein, a psychologist at
Brookhaven Lab. \"These results also attest to the benefit of using
sophisticated brain-imaging tools combined with sensitive behavioral,
cognitive, and emotional probes to optimize the study of drug addiction,
a psychopathology that these tools have helped to identify as a disorder
of the brain.\"\
\
Goldstein presented details of these studies at a press conference on
neuroscience and addiction at the Society for Neuroscience (SfN) annual
meeting in Atlanta, Georgia, on Sunday, October 15, 2006, and at a SfN
symposium on Wednesday, October 18.\
\
Goldstein\'s experiments were designed to test a theoretical model,
called the Impaired Response Inhibition and Salience Attribution
(I-RISA) model, which postulates that drug-addicted individuals
disproportionately attribute salience, or value, to their drug of choice
at the expense of other potentially but no-longer-rewarding stimuli \--
with a concomitant decrease in the ability to inhibit maladaptive drug
use. In the experiments, the scientists subjected cocaine-addicted and
non-drug-addicted individuals to a range of tests of behavior,
cognition/thought, and emotion, while simultaneously monitoring their
brain activity using functional magnetic resonance imaging (fMRI) and/or
recordings of event-related potentials (ERP).\
\
In one study, subjects were given a monetary reward for their
performance on an attention task. Subjects were given one of three
amounts (no money, one cent, or 45 cents) for each correct response, up
to a total reward of \$50 for their performance. The researchers also
asked the subjects how much they valued different amounts of monetary
reward, ranging from \$10 to \$1000.\
\
More than half of the cocaine abusers rated \$10 as equally valuable as
\$1000, \"demonstrating a reduced subjective sensitivity to relative
monetary reward,\" Goldstein said.\
\
\"Such a \'flattened\' sensitivity to gradients in reward may play a
role in the inability of drug-addicted individuals to use internal cues
and feedback from the environment to inhibit inappropriate behavior, and
may also predispose these individuals to disadvantageous decisions \--
for example, trading a car for a couple of cocaine hits. Without a
relative context, drug use and its intense effects \-- craving,
anticipation, and high \-- could become all the more overpowering,\" she
said.\
\
The behavioral data collected during fMRI further suggested that, in the
cocaine abusers, there was a \"disconnect\" between subjective measures
of motivation (how much they said they were engaged in the task) and the
objective measures of motivation (how fast and accurately they performed
on the task). \"These behavioral data implicate a disruption in the
ability to perceive inner motivational drives in cocaine addiction,\"
Goldstein said.\
\
The fMRI results also revealed that non-addicted subjects responded to
the different monetary amounts in a graded fashion: the higher the
potential reward, the greater the response in the prefrontal cortex. In
cocaine-addicted subjects, however, this region did not demonstrate a
graded pattern of response to the monetary reward offered. Furthermore,
within the cocaine-addicted group, the higher the sensitivity to money
in the prefrontal cortex, the higher was the motivation and the
self-reported ability to control behavior.\
\
The ERP results showed a similarly graded brain response to monetary
reward in healthy control subjects, but not in cocaine-addicted
individuals.\
\
\"The dysfunctional interplay between reward processing and control of
behavior observed in these studies could help to explain the chronically
relapsing nature of drug addiction,\" Goldstein said. \"Our results also
suggest the need for new clinical interventions aimed at helping drug
abusers manage these symptoms as part of an effective treatment
strategy.\"\
\
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\
This work was funded by the Office of Biological and Environmental
Research within the U.S. Department of Energy\'s Office of Science; the
National Institute on Drug Abuse; the National Alliance for Research on
Schizophrenia and Depression (NARSAD) Young Investigator Award; the
National Institute on Alcohol Abuse and Alcoholism; and the General
Clinical Research Center at University Hospital Stony Brook. DOE has a
long-standing interest in brain-imaging studies on addiction.
Brain-imaging techniques such as MRI are a direct outgrowth of DOE\'s
support of basic physics and chemistry research.\
\
Coauthors on the study included: Nelly Alia-Klein, Dardo Tomasi, Lisa A.
Cottone, Thomas Maloney, Frank Telang, and Elisabeth C. Caparelli of
Brookhaven Lab; Lei Zhang, Dimitris Samaras, and Nancy K. Squires of
Stony Brook University; Linda Chang and Thomas Ernst of the University
of Hawaii; and Nora D. Volkow of the National Institute on Drug Abuse.\
\
One of ten national laboratories overseen and primarily funded by the
Office of Science of the U.S. Department of Energy (DOE), Brookhaven
National Laboratory conducts research in the physical, biomedical, and
environmental sciences, as well as in energy technologies and national
security. Brookhaven Lab also builds and operates major scientific
facilities available to university, industry and government researchers.
Brookhaven is operated and managed for DOE\'s Office of Science by
Brookhaven Science Associates, a limited-liability company founded by
the Research Foundation of State University of New York on behalf of
Stony Brook University, the largest academic user of Laboratory
facilities, and Battelle, a nonprofit, applied science and technology
organization.\
\
Contact: Karen McNulty Walsh\
[DOE/Brookhaven National Laboratory](http://www.bnl.gov/)