Our brains as well as our faces virtually 'light up', especially when we laugh on hearing or seeing something funny.

The more hilarious a joke is, the greater the activity seen in 'reward centres', specific neurons (nerve and brain cells) which create feelings of pleasure.

And learning how humour affects the brain could help determine whether patients in a vegetative state experience positive emotions, the Journal of Neuroscience reports.

A team of Medical Research Council (MRC) scientists scanned the brains of volunteers to compare what happened when they heard ordinary sentences and jokes. This showed that the reward centres 'lit up' much more in response to humour, according to the Daily Mail.

Researcher Matt Davis, from the MRC Cognition and Brain Sciences Unit in Cambridge, said: "We found a characteristic pattern of brain activity when the jokes used were puns."

"For example, jokes like "Why don't cannibals eat clowns? Because they taste funny!" involved brain areas for language processing more than jokes that didn't involve wordplay.

"This response differed again from non-humorous sentences that also contained words with more than one meaning," said Davis.

"Mapping how the brain processes jokes and sentences shows how language contributes to the pleasure of getting a joke."

"We can use this as a benchmark for understanding how people who cannot communicate normally react to jokes," added Davis.