By John von Radowitz
LONDON, March 9 PA - US scientists have worked out why Homer Simpson finds doughnuts so impossible to resist.
A study found that two areas of the brain leapt into action when hungry volunteers were shown photos of Krispy Kremes, the popular glazed doughnuts from the US.
The same response did not occur after participants had stuffed themselves with up to eight of them.
Researchers at Northwestern University in Chicago carried out functional magnetic resonance imaging (fMRI) brain scans while volunteers were shown pictures of doughnuts and screwdrivers.
After the eating binge, neither image generated much of a reaction.
But after volunteers had fasted for eight hours, two distinct parts of the brain lit up'' at the sight of the doughnuts. The first was the limbic brain, an ancestral part of the brain present in all animals from frogs to humans. That part of the brain is able to detect what is motivationally significant,’’ said Dr Marsel Mesulam, senior author of the research published on line in the journal Cerebral Cortex.
``It says, not only am I hungry, but here is food.’’
Next the brain’s spatial attention network locked onto the doughnuts, deciding they were more important than the screwdrivers.
Dr Aprajita Mohanty, another of the scientists, said: There's a very complex system in the brain that helps to direct our attention to items in the environment that are relevant to our needs, for example, food when we are hungry but not when we are full.'' The research demonstrated how the brain sifts out all sorts of relevant material, not just doughnuts, from a world full of stimuli. If you are in a forest and you hear rustling, the context urges you to pay full attention since this could be a sign of danger,’’ said Dr Mesulam.
``If you are in your office, the context makes the identical sound less relevant. A major job of the brain is to match response to context.’’