Unwitting sight of food stokes appetite, brain scientists say

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Are there images of food around your home? They may be making you hungry, even if you are not aware of seeing them.

Analysis of brain activity by a group of scientists at Kyoto University and other institutions showed that food-related information likely stokes appetite-related emotions at a subconscious level.

Researchers on the team showed images of such food as hamburgers, as well as meaningless mosaic images, to 22 male and female subjects between the ages of 18 and 25 who had not eaten for about six hours. They used functional magnetic resonance imaging, a technology that uses blood flow changes to analyze brain activity, to study how their brains reacted.

The study showed that activity rose in the brain’s amygdala region, which is responsible for emotions, when food images were shown for 1.5 seconds. The same area also showed enhanced activity when similar images were shown for only about 0.02 second, so that the subjects did not realize they were seeing them.

The mosaic images seldom increased activity levels.

Wataru Sato, who led the team of scientists, said that subconsciously viewed images could still prompt human brains to transmit information.

“Our finding could help develop methods for arousing a strong appetite subconsciously,” said Sato, who is a program-specific associate professor of brain science with Kyoto University.

The research results were published May 13 in Scientific Reports, a British science journal.

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