New study reveals more about how the brain responds to rewards

A new study which investigated how the brain responds to social and non-social rewards could lead to improvements in treating disorders such as depression, autism and substance and behavioural addictions.

Humans are naturally driven to seek rewards as they respond to our basic needs and give us pleasure, but this can lead to risk-taking behaviour such as drug taking. 

Psychologists from Essex and Vienna set out to discover the role of different brain chemicals in firstly making us want a reward and then in how much we like the reward once we get it.

Previous research on animals has shown that opioid chemicals in the brain are linked to both wanting and liking a reward, while the dopamine chemicals are more associated with wanting. 

Dr Sebastian Korb, from the Department of Psychology at the University of Essex, was one of the authors and he explained: “Our study aimed to find out if the same was true for humans and if so, whether this could lead to a better understanding of abnormal reward processing. 

“For example, we already know that typically those with autism spectrum disorders don’t respond to social rewards in the same way as others, but to what extent social and non-social rewards are processed differently in the brain remains debated.”

Over 100 participants were each given a pill containing either an opioid receptor blocker, a dopamine receptor blocker or a placebo. Three hours later researchers measured how much participants wanted and liked a non-social food reward – chocolate milk or a social reward – a gentle caress of the forearm.

In each study participants pressed a force-measuring device with their hand to increase the chances of obtaining a reward, so that how much effort they were willing to put into getting the reward could be measured. 

They also rated their wanting (before) and liking (afterwards) of the reward, and their facial expressions – smiling or frowning – were monitored using face electrodes.

“We found that reward anticipation (wanting) was modulated by both chemicals but that only the opioid suppressant affected facial expressions of liking the reward. The findings were more pronounced for food rewards.

“These results are in line with previous animal research and allow for a better understanding of the role of brain chemicals in the way we respond to rewards.

“This may help us improve the way we treat addiction, but further research is needed to explain the partial difference we found between social and non-social rewards and the relationship this could have with developmental disorders such as autism,” said Dr Korb.

Results from the study, which was directed by Assistant-Professor Giorgia Silani, from the University of Vienna, have been published in eLife.