Dopamine and decisions

Striking a balance between short-term goals - going out for a meal with friends or buying a new book - and long-term objectives like saving up for a house or a holiday can be tricky. Researchers at University College London have been investigating the role of dopamine in these thought processes and have found that too much of the chemical - which is found naturally and plays a part in transmitting signals in the brain - might make you more likely to take the short-term option. The researchers studied 14 healthy participants asking them to make a choice between a small reward now or a larger one later. They were asked to make the decision after being given a drug called L-dopa, which boosts dopamine, a placebo and a drug called haloperidol which suppresses dopamine. After taking the L-dopa the participants were more likely to take the short-term option although there was little difference between their decisions after taking the placebo or after taking haloperidol. The participants also had brain scans while they took the tests. The L-dopa increased activity in the striatum and prefrontal cortex and the more susceptible people were to the influence of the L-dopa the more activity they showed in their amygdalas.

You can find out more about this research at

http://www.sciencedaily.com/releases/2010/06/100629170922.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader

Learning and dopamine

Researchers at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig and at University College London have been looking into the ways the brain 'rewards' itself for getting answers right. People who are rewarded for making correct decisions learn quickly. Previous research has shown that when a correct decision is made the brain's reward system is activated and a reward stimulus is sent back to the area of the brain responsible for making the decision. The researchers thought that the neurotransmitter dopamine played a part in this. In their experiment they attached electrodes to both index fingers of the participants. Two electric currents, each with a different frequency, were applied via the electrodes and the participants had to decide which current had the higher frequency. If they guessed right a monetary reward was flashed on a screen. The higher the reward that was displayed the more accurate the participants' guesses were. To look into the effects of dopamine on this process a third of the participants were given Levopoda (which increases dopamine), a third were given Haloperidol (which decreases it) and a third were given a placebo. The 'reward effect' was greatest in the group taking Levopoda and completely absent in the group taking Haloperidol. However, dopamine is implicated in psychosis and schizophrenia so for any dopamine-boosting learning drug the side effects might end up being worse than the original problem.


You can find out more about this research at

http://www.sciencedaily.com/releases/2009/07/090727203624.htm