London, Nov 13 (IANS) People make complex decisions, which include pleasurable activities like eating out or going to a movie. Now, a new study says that dopamine, a chemical in the brain, could govern such choices by influencing our expectations of the pleasure associated with these activities.
When dopamine is released, it provides feelings of enjoyment and reinforcement, and motivates us to do or continue doing certain activities.

“Humans make much more complex decisions than other animals — such as which job to take, where to vacation, whether to start a family — and we wanted to understand the role of dopamine in making these types of decisions,” said Tali Sharot from University College London.

“Our results indicate that when we consider alternative options when making real-life decisions, dopamine has a role in signalling the expected pleasure from those possible future events. We then use that signal to make our choices,” Sharot said.

Dopamine’s role in reward learning and reward-seeking behaviour has been established in animals, Sharot explained.

Her team recently found that when we imagine future events, activity in a dopamine-laden part of the brain tracks people’s estimates of the expected pleasure to be derived from those events.

Based on these findings, the researchers suspected that they could alter people’s expectations, and with them their choices, by manipulating dopamine levels in the subjects’ brains.

Researchers first asked people to rate their expectation of happiness if they were to vacation at each of 80 destinations, from Thailand to Greece.

They then gave the participants either L-DOPA (a drug that increases dopamine concentrations) or a placebo and asked them to imagine vacationing in those destinations.

The next day, participants had to pick between a series of paired destinations that they had initially assigned with equal ratings.

The researchers found that the ratings for particular vacation places increased after they were imagined under L-DOPA’s influence. That increase also affected people’s selections between two alternatives the following day, a University College release said.

“We had reason to believe that dopamine will enhance expectations of pleasure in humans,” Sharot said. “However, we were surprised at the strength of this effect. The enhancement lasted at least 24 hours and was evident in almost 80 percent of the subjects.”

These findings were published online in the Thursday edition of Current Biology.