A generation of young people is growing up with the logos of fast-food companies "branded" on their brains. Scientists say scans of children show the pleasure and appetite centres of their brains light up when they are shown advertising images such as the McDonald's logo.

The study reveals that the same areas do not respond to well-known logos that are not to do with food. It suggests fast-food firms are tapping into the reward areas of the brain, and that these develop before the regions that provide self-control, leading to unhealthy choices.

"Research has shown children are more likely to choose those foods with familiar logos," said Dr Amanda Bruce, who led the study. "That is concerning because the majority of foods marketed to children are unhealthy, calorifically-dense foods high in sugars, fat, and sodium."

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The study, conducted at the University of Missouri-Kansas City and the University of Kansas Medical Center, selected 120 popular food and non-food brands, including McDonald's and Rice Krispies, and BMW and FedEx. They used a type of MRI scanner – functional magnetic resonance imaging – which homes in on changes in blood flow: when areas of the brain become more active, blood flow increases.

Scans were carried out on children aged 10 to 14 as they were exposed to 60 food and 60 non-food logos. The results showed the food logos triggered increased activity in areas of the brain known to be involved in reward processing and in driving and controlling appetite.

The finding comes in the wake of research which showed advertising had a pronounced effect on children's eating habits. Children who tasted two identical burgers, one in a plain box and one labelled McDonald's, preferred the latter.

"The theory is the increase in risk-taking behaviour in adolescence is attributed to uneven development in brain regions associated with cognitive control and emotional drive," said Dr Bruce. "The brains of children are 'imprinted' with food logos. Without the necessary inhibitory processes to aid in decision-making, youth are particularly susceptible to making poor choices about what to eat."