Building a Brain Implant for Smell

Building a Brain Implant for Smell

Karen Weintraub

Researchers are developing a device that could restore olfaction, much as a cochlear implant restores hearing

Although the nerves that control smell can often regrow after an injury—they are some of the only neurons known to rapidly replace themselves—Moorehead's lesion was too severe. He now has anosmia, which means his sense of smell is gone. But he is participating in a nascent effort at the Virginia Commonwealth University (VCU) School of Medicine and Harvard Medical School to develop a partially implantable device that could help people with brain injuries decode and interpret everyday scents.

Research on smell lags decades behind that on vision and hearing, says Joel Mainland, an olfactory neuroscientist and associate member of the Monell Chemical Senses Center in Philadelphia, who is not involved in the new work. Smell studies receive less funding than research on other senses does, he says. And smell involves many sensory components. Whereas vision requires interpreting input from three types of receptors, taste involves 40 and olfaction 400.

A surprisingly large number of people have an impaired sense of smell—23 percent of U.S. adults age 40 and older, according to one national survey, and 62.5 percent of those age 80 and older, according to another. Such a decline can result from injury, chronic sinus problems, genetics or aging, says VCU professor Richard Costanzo, who has studied smell for four decades and is co-leading the initiative to develop the new device. Often dismissed as inconsequential, smell contributes to taste, so people who cannot smell are at risk for malnutrition, as well as social isolation, Costanzo says.