Our eyes function like noses: researchers have discovered that we perceive scents through the shapes of objects.

Most people rarely consider how their senses work—until something disrupts their function. However, the ability to see, smell, and perceive the world as it is today has been shaped over millions of years. What seems ordinary—a whiff of coffee or the sight of a ripe banana—is the result of complex interactions among different parts of the brain. And, as new research has shown, some of these connections are much deeper than previously thought, as reported by Salon.

A study published in the journal Nature examined how smells are represented in the human brain at the most fundamental level: at the level of individual neurons. For a long time, scientists were unable to study this process in humans due to ethical considerations, as recording the activity of individual neurons typically requires invasive procedures. However, patients with epilepsy undergoing diagnostic surgery provided a unique opportunity to do so.

As part of their treatment, deep electrodes were implanted in their brains, allowing researchers to insert ultra-thin micro-wires to record neuronal activity without additional risk to the patients. During the study, participants were exposed to various smells—banana, garlic, licorice—and were also shown corresponding images and words.

The results revealed something unusual: certain neurons in the piriform cortex—the area of the brain responsible for smell—were activated not only in response to the odor but also when a person viewed an image of the corresponding object or read its name. Similar activity was found in the amygdala—an area associated with memory and emotions. These neurons, termed "olfactory conceptual cells," suggest that the brain links smells, sights, and words more closely than previously believed.

Out of 1,856 neurons, 66 responded to both visual and olfactory stimuli, puzzling researchers. It is generally accepted that sensory processing areas operate independently of one another—one would not expect the brain's olfactory center to react to a written word or an image.

The lead author of the study Florian Mormann proposed that this phenomenon may reflect "olfactory imagery"—the ability to mentally recreate a smell based on visual cues. If this is the case, it could explain why seeing familiar food immediately evokes its scent, even in its absence. Their work is related to a broader concept known as cross-modal correspondences, where people instinctively link sensory features across different modalities.

Research has shown that most individuals associate certain tastes with specific shapes or sounds: sweetness with round shapes, bitterness with angular shapes, and even high-frequency sounds with sour tastes. This effect, observed across various cultures, suggests a neurological basis for the processing and integration of sensory information.

These findings pave the way for both new insights and new questions regarding perception, memory, and even language. If the brain connects smells with visual representations, does altering the appearance of an object change the perception of its scent? The idea that a rose by any other name would smell as sweet may hold true, but if its color or shape is changed, will the sensations remain the same? The intricate network of sensory connections in the brain indicates that perception is far more complex than it appears at first glance.