Two regions of the brain have been discovered that react most strongly to images of food.
Researchers have previously identified regions of the brain鈥檚 visual system that are selectively activated by faces, words and places. It is believed that these items require specialist processing in the brain because they are especially important for socialising and survival.
But no such region had been conclusively found that was activated by looking at food. Two studies published this year suggested that such a region , but neither study conclusively demonstrated that the activation observed was due to the food item and not the colour of the images.
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To investigate further, at Carnegie Mellon University in Pittsburgh, Pennsylvania, and her colleagues conducted two experiments.
First, the team analysed data from a year-long study in which eight people looked at 10,000 different images while they had their brains scanned in a functional magnetic resonance imaging (fMRI) machine. The images typically contained more than one object and were similar to photographs that would be taken in everyday life.
The researchers took 1000 of these images that had been seen at least once by each participant and analysed the corresponding fMRI data. More than half of the images were seen by each participant three times over the course of a year. 鈥渇MRI data tends to be noisy and using the same stimulus multiple times means you can average across the repetitions of the stimulus and get a cleaner image,鈥� says Wehbe.
The team identified two brain regions in all the participants that were preferentially activated by images of food. These regions were in the ventral visual cortex and were on either side of an area implicated in facial recognition. They matched the brain regions found in previous studies to be activated by food.
In the second experiment, the researchers put four new people into an fMRI scanner and showed them images of various objects. Unlike the first experiment, these images were in greyscale and only contained a single object, but the same brain regions were consistently activated by images of food.
While the two experiments each had small sample sizes, Wehbe says she is confident in the results and the team was able to rule out the possibility that the colour or perspective of the items in the images was activating these regions of the brain.
鈥淭he most intuitive explanation is that food is a category which is quite important from an evolutionary perspective,鈥� says Wehbe. 鈥淚t鈥檚 something we need to process quickly and so it makes sense to have a dedicated area for it.鈥�
at the Massachusetts Institute of Technology says the findings echo those . 鈥淔oraging 鈥� searching for food 鈥� is one of the brain鈥檚 most important functions and is essential for human well-being,鈥� says Khosla. 鈥淚n humans, this activity primarily relies on vision, especially when it comes to finding those foods we are already familiar with.
鈥淏eyond that, food is not just sustenance, but also has a distinctive importance in human culture and is at the centre of our social interactions and cultural identity,鈥� she says. 鈥淎ny or all of these factors could have contributed to the development of food selectivity in the human ventral visual cortex.鈥�
Reference: bioRxiv, DOI:
