When we eat and drink, different zones in our brain respond to the taste and smell of food as well as other sensory properties. Scientists in the Perception Physiology Group at the Nestlé Research Center (NRC) use a technique called electro-encephalography (EEG) to record exactly where and when the flavour of food and other properties are processed in the brain once they enter the oral cavity.
During an EEG, volunteers wear a cap that tightly covers the head with a network of electrodes on the inside. These electrodes pick up brainwave signals from the scalp and are sensitive enough to pinpoint the exact location within the brain where the imprint of a certain food ingredient has landed.
What are brainwaves and what do they do?
Brainwaves are the result of electrical signals given off by neurons when they communicate with each other. They are by nature very complex as they are generated by billions of interconnected neurons sending each other micro-volt range electrical pulses. EEGs measure the sum of simultaneously generated pulses by capturing the signals via electrodes placed on the scalp.
Brainwaves can be classified as slow, moderate or fast waves depending on their speed, measured in Hertz (cycles per second). Although no single brainwave is responsible for a single function, there are some generalities that link specific types of brainwaves to specific states of mind. For example, alpha waves are linked to periods of quiet and calm and can be notably generated during meditation1. Beta waves are linked to moments of cognitive tasks such as decision-making and problem-solving2.
EEGs pick up these brainwaves while volunteers sample specific kinds of food and will generate an electrical image of the impact of each foodstuff on the brain, which proves extremely helpful in identifying how our bodies and minds react to certain kinds of food.
Message from the brain: Wake up!
In a test, Dr Julie Hudry at the Nestlé Research Center compared the stimulating feeling of eating an ice cube with that of drinking a glass of cold water. The ice cube gives off a cold, juicy, tingling delicious sensation that refreshes the mouth and head. Why? Because the refreshing stimulus sets off a myriad of tiny electrical impulses all over the scalp! Dr Hudry used EEG to compare the brainwaves related to both these actions. The ‘cool’ refreshing feeling in the mouth was measured as it increased the amplitude of the brain’s α-waves. The figure on the right shows a comparatively greater increase in α-wave activity over the whole scalp with ice than with water alone, interpreted as a tingling sensation of increased alertness.
LABBE D., MARTIN N., LE COUTRE J., HUDRY J., 2011. Impact of refreshing perception on mood, cognitive performance and brain oscillations: An exploratory study. Food Quality and Preference, 22, 92-100