Navigation Links
Altered perception of reward in human cocaine addiction

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.

"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 will present 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, 2 to 3 p.m., and at a SfN symposium on Wednesday, October 18, 8:30 a.m.*

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-repor ted 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."

Source:DOE/Brookhaven National Laboratory

Related biology news :

1. Researchers offer proof-of-concept for Altered Nuclear Transfer
2. Color perception is not in the eye of the beholder: Its in the brain
3. Cracking the perception code
4. UC Riverside psychologist explores human perception, finds wow factor
5. Face perception is modulated by sexual orientation
6. Patients and their doctors have different perceptions about HIV and its treatment
7. Loves all in the brain: fMRI study shows strong, lateralized reward, not sex, drive
8. Nicotine triggers the same brain reward circuitry as opiates
9. Dissecting the machinery of nicotines reward
10. Leptin has powerful effect on reward center in the brain
11. Brains reward circuit activity ebbs and flows with a womans hormonal cycle

Post Your Comments:

(Date:10/12/2015)... , Oct. 9, 2015 Research and Markets ... Research, Inc,s new report "Biometrics: Market Shares, Strategies, ... --> --> The ... the Biometrics market segment. Research represents a selection from ... and cogent market materials, with selections made by the ...
(Date:10/12/2015)... -- Research and Markets ( ) has ... Market by Component (Hardware & Software), Product (Scanner ... (Travel & Immigration, Military & Defense, & Others) ... report to their offering. ... worth 3627.90 Million USD by 2020 ...
(Date:10/8/2015)... Oktober 2015 Die Track Group, ... des Bereiches Tracking, hat heute bekannt gegeben, ... Virginias (Department of Corrections – DOC) unterzeichnet ... alle Strafen geliefert werden, die der Behörde ... für den Amerikanischen Kontinent der Track Group. ...
Breaking Biology News(10 mins):
(Date:10/12/2015)... , Oct. 12, 2015  Patara Pharma, ... allergic and inflammatory diseases and conditions, today announced ... preferred stock financing. Concurrent with the close of ... into a Loan and Security Agreement with Silicon ... to $7 million. Patara will use the funds ...
(Date:10/12/2015)... NAMUR , Belgium , Oct. 12, ... today announced that full results from a completed clinical study ... pancreatic cancers have been published in the online issue of ... Epigenetics Society. The peer-reviewed study was conducted in collaboration with ... , and led by Roland Andersson , MD, PhD, ...
(Date:10/12/2015)... ... 2015 , ... LifeTrak , a leader in consumer fitness, heart rate ... amphibious fitness tracker that seeks to meet the needs of multi-sport athletes. Zoom is ... monitoring both in water and on land, making it the only fitness tracker ...
(Date:10/10/2015)... ANNAPOLIS, Maryland , 10. Oktober, 2015 /PRNewswire/ ... O. Matsui (Abgeordnete der Demokratischen Partei für Kalifornien) ... 11. bis 17. Oktober) in die Aufzeichnungen des ... Plasma Protein Therapeutics Association (PPTA) und ... , Hebung des Bewusstseins über Plasmaspenden ...
Breaking Biology Technology: