When we eat sugary treats, our brains release dopamine. Which is why it makes us feel good and can be so addictive. 🧁😋

Recent breakthroughs in brain-scanning technology have discovered multi-sensory regions which act as convergence zones, where signals from different senses are processed. 🧠🧬

One of these regions is the orbitofrontal cortex where your sense of smell and taste are both processed. 👃👅

This results in the cross-modal sensory compensation effect. Where signals from your sense of smell and taste combine, interact, and influence each other. 👫

So when we smell Killa Vanilla, we’re tricking our brains into thinking we’ve had sugary treats. Without the calories! 🤭🙌

"FOOD AND SCENT SIGNALS ARE PROCESSED IN THE SAME PART OF BRAIN WHERE THEY INFLUENCE AND SUBSTITUTE FOR EACH OTHER; SO EXPOSURE TO INDULGENT SCENTS CAN TRICK YOUR BRAIN INTO THINKING YOU'VE EATEN SUGARY TREATS"

Keep reading for sciencey bit. 🧑‍🔬

 

The Science

The human brain consists of one hundred billion neurons and one hundred trillion distinguishable substructures, all connected in complex synaptic networks. Understanding what it does and it works is an extremely complicated task!

Fortunately, over the past few decades advancements in neuroimaging technology have allowed us to better study the structure and functions of our brains. Specifically, it has helped to understand sensory processing; the way that the brain receives signals from the different senses and produces responses to them.

It was previously thought that each structure had a specific function, but it is now understood that there are multisensory regions that act as convergence zones where inputs from different sensory modalities combine, interact, and influence each other1,2.

"THERE ARE MULTISENSORY REGIONS IN THE BRAIN THAT ACT AS CONVERGENCE ZONES WHERE INPUTS FROM DIFFERENT SENSORY MODALITIES COMBINE, INTERACT, AND INFLUENCE EACH OTHER."

Amongst our five senses, the olfactory and gustatory systems are especially interconnected3,4,5. Together with the trigeminal system, they make up the chemosensory system, which is responsible for flavour perception6.

For the gustatory system, the primary taste cortex is the anterior insula7,8,9, which first processes signals from the gustatory system, but is not responsible for determining the reward value of food10. It has been discovered that this instead takes places in the secondary taste cortex, the orbitofrontal cortex11.

So, when we eat sugar, it is the orbitofrontal cortex that activates the reward circuitry and triggers the release of dopamine. This is why we feel good when we eat sugar, and why it can be so addictive.

It has recently been discovered that the orbitofrontal cortex is not just responsible for processing these signals from gustatory stimuli, but instead, it is one of the multisensory regions and is also responsible for processing signals from olfactory stimili6,12,13.

As with gustatory signals, when processing signals from olfactory stimuli one of the jobs of the orbitofrontal cortex is to determine the reward value14, and high-calorie, high-fat, sugar-laden indulgent foods tend to have the highest reward values15. Once a stimulus with a high reward value is identified, the brain’s reward circuitry, primarily composed of the dopamine system, is activated16,17.

"THE ORBITOFRONTAL CORTEX IS RESPONSIBLE FOR PROCESSING SIGNALS FROM THE OLFACTORY AND GUSTATORY SYSTEMS, BUT CAN'T DISTINGUISH THE DIFFERENCE BETWEEN THE SOURCES."

This reward intensity then has the same effect on the brain that indulgent foods have18. This is because whilst the orbitofrontal cortex discriminates between stimuli on the basis of valence as well as the intensity of the reward value19,20, it does not discriminate among the sensory modalities in which the stimuli are encoded21.

This is the key to the cross-modal sensory compensation effect; where stimuli from one sense can satisfy the desire related to another sense5, proving sensory-specific satiety does not require food to enter the gastrointestinal system and does not depend on the ingestion of calories23.

"THE CROSS-MODAL SENSORY COMPENSATION EFFECT; WHERE STIMULI FROM ONE SENSE CAN SATISFY THE DESIRE RELATED TO ANOTHER SENSE."

This powerful effect of the olfactory sense is often overlooked and is only just beginning to be understood. However, it is particularly suited to achieving satiety as the body can adjust its responses rapidly to differing aromas24. As technology advances further and we understand more about how our brains process signals, there could be many more exciting opportunities to influence how it works and help us all reach our goals.

 

Cross-Modal Sensory Compensation EffectFig.1 - Cross-Modal Sensory Compensation Effect

 

The Trials

Trials were conducted in supermarkets and cafeterias, and then replicated in lab controlled settings.☕🛒🔬

They measured they effects of different scents on peoples food choices by exposing them to scents for two minutes and analysing what they bought and ate. ⏱️📓

In all cases, they found people made better food choices, even when they weren’t consciously aware of being exposed to the scent. 🙌💪

 

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