Smells as good as it tastes? Researchers explore how the brain interprets scents & taste

A new study from Karolinska Institute in Sweden, published in Nature Communications, has revealed that the brain interprets certain aromas as taste when consuming foods. The study, conducted in collaboration with researchers in Turkey and funded by the European Research Council (ERC) and the Swedish Research Council, could reveal why sometimes people can experience taste from smell alone.

When we eat or drink, we experience taste, not just the “flavor” of foods. This taste experience arises from a combination of taste and smell, where aromas from food reach the nose via the oral cavity, known as retronasal odor. 

Tasting earlier than expected 

The researchers note that the brain integrates these signals earlier than previously thought — already in the insula, a region known as the taste cortex — before the signals reach the frontal cortex, which controls our emotions and behaviors.

“We saw that the taste cortex reacts to taste-associated aromas as if they were real tastes,” explains lead author Putu Agus Khorisantono, researcher at the Department of Clinical Neuroscience, Karolinska Institutet, Sweden. 

“The finding provides a possible explanation for why we sometimes experience taste from smell alone, for example, in flavored waters. This underscores how strongly odors and tastes work together to make food pleasurable, potentially inducing craving and encouraging overeating certain foods.”

The study involved 25 healthy adults who were first taught to recognize both a sweet and savory taste through combinations of taste and smell. This was then followed by two brain imaging sessions using functional magnetic resonance imaging (fMRI), in which the participants were given either a tasteless aroma or a taste without smell.

The researchers trained an algorithm to recognize patterns in brain activity for sweet and savory tastes. Then, they tested whether the same patterns could be identified when the participants were only given aromas.

Activating taste

The results showed that aromas perceived as sweet or savory not only activated the same parts of the brain’s taste cortex as the actual tastes but also evoked similar patterns of activation. According to the researchers, this overlap was particularly evident in the parts of the taste cortex linked to the integration of sensory impressions.

“This shows that the brain does not process taste and smell separately, but rather creates a joint representation of the flavor experience in the taste cortex,” says the study’s last author, Janina Seubert, senior researcher at the same department at Karolinska Institutet. 

“This mechanism may be relevant for how our taste preferences and eating habits are formed and influenced.”

The researchers now plan to investigate whether the same mechanism applies to external smells, known as orthonasal odors.

“We want to find out whether the activation pattern in the brain’s taste cortex changes from salty to sweet when we walk from the cheese aisle to the pastries in the supermarket,” says Khorisantono. “If so, this could have a significant impact on the foods many of us choose to consume.”