Approximately 20% of the world’s population – over a billion people – suffer from anosmia (complete loss of smell) or hyposmia (partial loss of smell), which can be caused by infections, injuries, or medications.
The process of olfactory perception (olfaction) begins when volatile, hydrophobic compounds from the external environment—odorants—reach the olfactory epithelium, located in the upper part of the nasal cavity, as a result of inhalation. These molecules bind to the olfactory receptors present on the epithelium.
This binding results in the transduction of the chemical signal into an electrical impulse, which is transmitted via the Olfactory Bulb to the brain, where the odor is identified. Accordingly, anosmia or hyposmia signifies a complete or partial disruption of this sensory pathway.
While cochlear implants or prostheses are available for hearing and vision impairments, until now, there was no technology capable of restoring the sense of smell.
However, scientists presented a revolutionary device in a paper published in the journal “Science Advances,” offering new hope. This device identifies specific odors and then converts them into a different type of sensation (such as vibration or a light tap) that a person perceives through the nose.
The olfactory sensory substitution program works as follows:
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Odor Identification and Encoding: The device uses e-nose technology to detect odor-producing molecules and translates this chemical information into a specific digital code.
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Nerve Stimulation: The digital code is transmitted via an intranasal electrical stimulator (a small magnetic clip) placed on the nasal septum. This stimulator activates the trigeminal nerve through electrical impulses.
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Sensation Perception: Upon activation of the trigeminal nerve, the individual perceives the code as a distinct sensation (touch, temperature, irritation).
There are two sensory systems in the nasal cavity: the olfactory system (for smell) and the trigeminal system (for touch/temperature). This device utilizes the trigeminal nerve to convey information that the olfactory nerve is no longer able to transmit.
Patients do not actually smell the odors, but their brain learns to associate the unique sensation with a specific smell, allowing them to differentiate between various odors.
The study’s authors tested the device in four experiments on 65 people (13 with a normal sense of smell and 52 with smell loss). The results showed that all participants were able to detect the odorant molecules, and most were able to distinguish between two different odors. Notably, the device worked equally well in both anosmic and healthy individuals, confirming that this system is a reliable way to transmit encoded signals.
Although the concept is in its early stages, the scientists plan to transform the laboratory prototype into a miniature, portable device for everyday use in the future.
წყარო: Science Advances
