Featured Research

from universities, journals, and other organizations

Impulsive, weak-willed or just too much dopamine? Brain study highlights role of dopamine in impulsive behavior

Date:
June 30, 2010
Source:
Wellcome Trust
Summary:
It's a common scenario: you're on a diet, determined to give up eating cakes, but as you pass the cake counter, all resolve disappears. Now, scientists have shed light on the brain processes that affect our will-power and make us act impulsively.

It's a common scenario: you're on a diet, determined to give up eating cakes, but as you pass the cake counter, all resolve disappears… Now, scientists at the Wellcome Trust Centre for Neuroimaging at UCL (University College London) have shed light on the brain processes that affect our will power and make us act impulsively.

In a study published in the Journal of Neuroscience, funded mainly by the Wellcome Trust, researchers led by Professor Ray Dolan have shown that increased levels of dopamine -- a chemical in the brain involved in mediating reward, motivation, and learning through reinforcement, -- make us more likely to opt for instant gratification, rather than waiting for a more beneficial reward.

The research may help explain why people affected by conditions such as Attention Deficit/Hyperactivity Disorder (ADHD), characterised by high levels of dopamine in the brain, tend to show extremely impulsive behaviour. Similarly, it highlights why such behaviour can be a potential negative side-effect of L-dopa, a drug used to help alleviate the symptoms of Parkinson's disease.

To test the effect of dopamine on decision-making, Professor Ray Dolan and colleagues carried out a test with 14 healthy volunteers under two conditions: once when given a small (150mg) dose of L-dopa, once when given a placebo. Under each condition, the subjects were asked to make a number of choices consisting of either a 'smaller, sooner' option, for example receiving 15 in two weeks, or a 'larger, later' option, such as receiving 57 in six months.

"Every day we are faced with decisions that offer either instant gratification or longer-term, but more significant reward," explains Dr Alex Pine, first author of the study. "Do you buy your new iPhone today or wait six months till the price comes down? Do you diet or eat that delicious-looking cake? Do you get out your books to study for a future exam or watch some more TV?"

The researchers found that every subject was more likely to behave more impulsively -- choosing the 'smaller, sooner' option -- when levels of dopamine in the brain were boosted. . On the whole, the number of sooner options chosen increased by almost a third, although each subject varied on this measure.

Dr Pine believes that this finding may also explain why we tend to behave more impulsively when influenced by external 'cues'.

"We know that sensory inputs -- sights, sounds smells and anticipation of rewards, or even of neutral cues which have been associated with rewards -- momentarily boost dopamine levels in our brains, and our research shows that higher dopamine levels make us act more impulsively," he says.

"But this research is important for more than just explaining our day to day lapses in self-control. It also helps us understand why disorders which are associated with abnormal dopamine functioning can also lead to extremely impulsive behaviour."

The researchers also tested the subjects under the influence of small doses of haloperidol, a dopamine suppressant; however, the results were inconclusive, showing little difference from the effect of the placebo. Dr Pine cautions against the idea that dopamine suppressants might be used to help combat impulsivity and addiction.

"Dopamine plays a wide role in the brain, from movement through to cognition," he explains. "Lowering dopamine levels may be able to reduce impulsivity, but we need to be certain that this didn't come at the expense of other, important functions."

The test was conducted whilst the subjects were in a functional magnetic resonance imaging (fMRI) scanner, which looks at activity in the brain by measuring changes in blood flow. A network of brain regions, including the striatum and prefrontal cortex, tends to be more active when considering a sooner versus a more delayed reward. The researchers showed that this differential activity was more magnified after the subjects were given L-dopa.

They also found that greater individual susceptibility to the influence of the drug was associated with an increase in activity in the brain region known as the amygdala when volunteers made choices. The amygdala is known to play a role in processing emotions, which affects decision-making, though the mechanism of this influence it is not yet fully clear.


Story Source:

The above story is based on materials provided by Wellcome Trust. Note: Materials may be edited for content and length.


Cite This Page:

Wellcome Trust. "Impulsive, weak-willed or just too much dopamine? Brain study highlights role of dopamine in impulsive behavior." ScienceDaily. ScienceDaily, 30 June 2010. <www.sciencedaily.com/releases/2010/06/100629170922.htm>.
Wellcome Trust. (2010, June 30). Impulsive, weak-willed or just too much dopamine? Brain study highlights role of dopamine in impulsive behavior. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2010/06/100629170922.htm
Wellcome Trust. "Impulsive, weak-willed or just too much dopamine? Brain study highlights role of dopamine in impulsive behavior." ScienceDaily. www.sciencedaily.com/releases/2010/06/100629170922.htm (accessed July 23, 2014).

Share This




More Mind & Brain News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Why Do People Believe We Only Use 10 Percent Of Our Brains?

Why Do People Believe We Only Use 10 Percent Of Our Brains?

Newsy (July 22, 2014) The new sci-fi thriller "Lucy" is making people question whether we really use all our brainpower. But, as scientists have insisted for years, we do. Video provided by Newsy
Powered by NewsLook.com
Do Obese Women Have 'Food Learning Impairment'?

Do Obese Women Have 'Food Learning Impairment'?

Newsy (July 18, 2014) Yale researchers tested 135 men and women, and it was only obese women who were deemed to have "impaired associative learning." Video provided by Newsy
Powered by NewsLook.com
Does Mixing Alcohol and Energy Drinks Boost Urge To Drink?

Does Mixing Alcohol and Energy Drinks Boost Urge To Drink?

Newsy (July 18, 2014) A new study suggests that mixing alcohol with energy drinks makes you want to keep the party going. Video provided by Newsy
Powered by NewsLook.com
Pot Cooking Class Teaches Responsible Eating

Pot Cooking Class Teaches Responsible Eating

AP (July 18, 2014) Following the nationwide trend of eased restrictions on marijuana use, pot edibles are growing in popularity. One Boston-area cooking class is teaching people how to eat pot responsibly. (July 18) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins