2. The brain's fatty food radar
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The human brain recognises the difference between low and high-fat food with
the same automatic efficiency as it exhibits when discriminating happy and
sad faces, and living and non-living entities. Ulrike Toepel and colleagues
who made the finding, hope it will contribute to our understanding of
over-eating.
The researchers presented 24 normal-weight participants with photos of
hundreds of different types of food, as well as pictures of kitchen
utensils, all the while recording their brain activity using
electroencephalography (EEG).
The participants thought their task was to indicate as fast as possible
whether each photo, presented for just half a second, showed food or a
kitchen utensil. In fact, the researchers were interested in whether the
brain activity of the participants differed according to whether a high or
low fat food had been presented.
The advantage of EEG over brain imaging techniques like fMRI, is in the
level of time-related detail it can provide. In this case, Toepel's team
were able to show that high-fat food led to distinct patterns of brain
activity relative to low-fat food, during two discrete time periods:
160-220ms and 330-370ms after presentation of the food.
The speed with which the fat content of food was discriminated by the brain
is similar to that shown for other fundamental categories such as for living
vs. non-living things. Because the participants were distracted by the task
involving kitchen utensils, the results further show that this
discrimination between high and low-fat foods occurs automatically.
Areas of the brain that showed sensitivity to food fattiness were
temporo-parietal regions during the first time period and the pre-frontal
cortex during the second time period. The first time period probably relates
to rudimentary analysis of the fattiness category, and the second probably
relates to decision making.
"Enhanced activation in prefrontal cortices has also been related to
syndromes of eating disorders," the researchers explained. "Thus, the
network identified during this second stage points to the role of this
categorization phase in the decision-making process on food choices based on
their energetic value."
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U TOEPEL, J KNEBEL, J HUDRY, J LECOUTRE, M MURRAY (2009). The brain tracks
the energetic value in food images. NeuroImage, 44 (3), 967-974
http://dx.doi.org/10.1016/j.
Author weblink: http://tinyurl.com/br735n
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