Homer Simpson may not be the only one with a region of the brain dedicated to doughnuts: researchers have found that images of food appear to trigger a specific set of neurons.
Previous research found that similar regions of the brain are highly specialised to identify and remember faces, places, bodies and words.
The team, based at the Massachusetts Institute of Technology (MIT), say they stumbled upon the food-sensitive neurons by accident – and they could have evolved due to the evolutionary and cultural importance of food for humans.
“Our most novel result is the discovery of a new neural response that has not been reported previously for the ventral visual pathway and that is highly selective for images of food,” the scientists wrote in the journal Current Biology.
The researchers examined brain scans of eight participants taken as they viewed 10,000 images. Pictures of food appeared to trigger a population of neurons in the ventral visual cortex, which processes visual information.
“We were quite puzzled by this because food is not a visually homogenous category,” said Meenakshi Khosla, one of the lead authors of the study. “Things like apples and corn and pasta all look so unlike each other, yet we found a single population that responds similarly to all these diverse food items.”
Cooked meals such as a cheesy slice of pizza provoked a slightly stronger reactions than raw fruit and vegetables, the researchers noted. To test whether this was due to warmer colours in prepared food, they compared participants’ reactions with cool-toned images of food and richly coloured non-food objects. They found food caused a sharper signal.
The team then fed 1.2m images into a computer model and found the 1,000 pictures that produced the strongest activation of the food-responsive neurons were of snacks and meals. Black-and-white images showed the same results.
The scientists also confirmed the preference for food by pairing very similar pictures of edible and inedible items, such as a banana and a yellow crescent moon. Participants saw between 20 and 40 pairs and their brain scans all showed a stronger response to the images of food.
The researchers posit these neurons have gone undetected because they are spread across the other specialised clusters for faces, places, bodies and words, rather than concentrated in one region. The team suggest that while it is unlikely there are specialised neurons for everything, it makes sense for the brain to have evolved a shortcut to detect food.
“Because food has been of fundamental importance to humans both throughout their evolution, and in modern daily life, and because food choice often starts with vision, a specialisation for food in the visual ventral cortex is consistent with both evolutionary and experiential origins of cortical specialisations,” they said.
