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Mass. Eye and Ear doctors send electrical signals into brain to create sensation of smells

Researchers at Massachusetts Eye and Ear say they’ve taken a first step toward restoring the sense of smell for people who have lost it. Suzanne Kreiter/Globe Staff/File 2018

Doctors at Massachusetts Eye and Ear say they’ve placed electrodes in the nose to stimulate people’s brains and cause them to smell onions and other smells that weren’t there, in an experiment that could be a first step toward a treatment someday of anosmia, the loss of the sense of smell.

“Our work shows that smell restoration technology is an idea worth studying further,” corresponding author Dr. Eric Holbrook, chief of rhinology at the hospital and associate professor of otolaryngology at Harvard Medical School, said in a statement.

Researchers placed electrodes in the nose to stimulate nerves in the olfactory bulb, part of the brain where smell information from the nose is processed and sent deeper into the brain. Their results were published in the journal International Forum of Allergy and Rhinology.


About 5 percent of the general population suffer from anosmia, with some estimates saying that more than half the population over 65 has experienced smell loss, the researchers said. While some cases can be treated because there’s an underlying cause such as nasal obstruction, others involve damage to the nerves in the nose. There are no proven therapies for such cases.

The researchers noted that smell contributes to safety and well-being. It can alert people to natural gas leaks or keep them from eating rotten food. It’s also important for nutrition because taste is tied to smell, and as flavor decreases, appetite decreases.

The researchers said they were motivated by work conducted by research colleagues at Virginia Commonwealth University’s School of Medicine.

The researchers said that they positioned electrodes in the sinus cavities of five patients who could smell. Three described smells, including onions, antiseptic, and sour and fruity aromas, as a result.

Researchers said they hoped one day for a “cochlear implant for the nose,” referring to the implant that restores hearing to people by electrically stimulating the auditory nerve.


In the future, more “effort, time and further technological advancement” will be needed to refine and improve implants, the study said. “Nevertheless, our study has provided a starting point for the development of olfactory stimulation. Elicitation of subjective olfactory sensations in a majority of subjects suggests the idea of a stimulator is feasible.”

Holbrook said, “There’s currently so little that we can do for these patients, and we hope to eventually be able to reestablish smell in people who don’t have a sense of smell. Now we know that electrical impulses to the olfactory bulb can provide a sense of smell — and that’s encouraging.”