Humans are capable of recognizing scents just as quickly as rodents, even though people breathe about ten times less frequently. Research has shown that both humans and mice share a common evolutionary mechanism for perceiving smells: during inhalation, the brain activates a special analysis cycle, switching neurons into a high-speed mode for instant odor detection.

Neurobiologists from Northwestern University (USA) conducted two experiments to study the sense of smell from different perspectives. In the first experiment, a robotic multi-video tracking system was used to observe freely moving mice. It was found that while sniffing food, rodents can temporarily suppress their usual rapid sniffing and instead take a single, precise inhalation, carefully synchronized with their body movements. At this moment, the animals use their front paws and turn their heads, consciously checking the food. Similar movements are observed in humans when assessing the freshness of products. When researchers tried to disable the sense of smell in mice, the animals continued this ritual, but blocking the motor cortex, which controls voluntary movements, stopped it completely.

The second experiment, involving healthy volunteers, allowed scientists to study the reverse side of this process. Using sensors that measure electrical signals in the brain’s olfactory center, it was discovered that when a person tries to smell something, low-frequency theta oscillations (from 2 to 8 hertz) arise, which are responsible for processing and structuring information. This frequency matches the rhythm of rapid breathing in rodents.

The human brain does not require multiple quick inhalations to recognize a scent. A single conscious breath is enough for the brain’s internal “processor” to quickly structure and analyze incoming information about the smell within fractions of a second, using rapid bursts of neural activity to capture the details of the aroma.

This mechanism is controlled by the brain’s motor cortex and depends on conscious attention and decision-making, rather than being an automatic reflex. Understanding how this ancient neural system works could help in the future with earlier diagnosis of diseases associated with impaired sense of smell, such as Parkinson’s disease, Alzheimer’s disease, and autism spectrum disorders.