Sense of smell: The nose and the brain make quite a team... in disconnection

August 12, 2013, University of Geneva

Alan Carleton's team from the Neuroscience Department at the University of Geneva (UNIGE) Faculty of Medicine has just shown that the representation of an odor evolves after the first breath, and that an olfactory retentivity persists at the central level. The phenomenon is comparable to what occurs in other sensory systems, such as vision or hearing. These movements undoubtedly enable the identification of new odors in complex environments or participate in the process of odor memorization. This research is the subject of a publication in the latest online edition of the journal PNAS (Proceedings of the National Academy of Sciences).

Rodents can identify odors in a single breath, which is why research on sense of smell in mammals focuses on that first inhalation. Yet we must remember that from a neurological standpoint, sensory representations change during and after the stimuli. To understand the evolution of these , an international team of researchers led by Professor Alan Carleton at the University of Geneva (UNIGE) Faculty of Medicine conducted the following experiment: by observing the brain of an alert mouse, the neuroscientists recorded the emitted by the of animals inhaling odors.

They were surprised to find that in mitral cells, some representations evolved during the first inhalations, and others persisted and remained stable well after the odor ceased. The cohort subjected to these analyses revealed that the post-odor responses contained an odor retentivity—a specific piece of information about the nature of odor and its concentration.

Will odor memory soon be understood?

Using cerebral imaging, researchers discovered that the majority of sensory activity is visible only during the presentation of odors, which implies that retentivity is essentially internal to the brain. Therefore, odor retentivity would not be dependent upon odorous physicochemical properties. Finally, to artificially induce retentivity, the team photostimulated mitral cells using channelrhodopsin, then recorded the persistent activity maintained at the central level. The strength and persistence of the retentivity were found to be dependent on the duration of the stimulation, both artificial and natural.

In summary, the were able to show that the representation of an odor changes after the first breath, and that an olfactory retentivity persists at the central level, a phenomenon comparable to what occurs in other , such as vision and hearing. These movements undoubtedly enable the identification of new odors in complex environments or participate in the process of odor memorization.

Explore further: Flies reveal that a sense of smell, like a melody, depends upon timing

More information: The journal PNAS has just published these findings in its latest online edition.

Related Stories

Flies reveal that a sense of smell, like a melody, depends upon timing

April 10, 2013
(Medical Xpress)—The sense of smell remains a mystery in many respects. Fragrance companies, for instance, know it is crucial that chemical compounds in perfumes reach nostrils at different rates to create the desired sensory ...

Researcher finds elderly lose ability to distinguish between odors

November 10, 2011
Scientists studying how the sense of smell changes as people age, found that olfactory sensory neurons in those 60 and over showed an unexpected response to odor that made it more difficult to distinguish specific smells, ...

Elderly humans can be identified by their unique body odor: research

May 30, 2012
New findings from the Monell Center reveal that humans can identify the age of other humans based on differences in body odor. Much of this ability is based on the capacity to identify odors of elderly individuals, and contrary ...

Anxiety boosts sense of smell

March 22, 2012
Anxious people have a heightened sense of smell when it comes to sniffing out a threat, according to a new study by Elizabeth Krusemark and Wen Li from the University of Wisconsin-Madison in the US. Their work¹ is published ...

Researchers identify critical link in mammalian odor detection

May 6, 2013
Researchers at the Monell Center and collaborators have identified a protein that is critical to the ability of mammals to smell. Mice engineered to be lacking the Ggamma13 protein in their olfactory receptors were functionally ...

Recommended for you

Playing high school football changes the teenage brain

November 16, 2018
A single season of high school football may be enough to cause microscopic changes in the structure of the brain, according to a new study by researchers at the University of California, Berkeley, Duke University and the ...

Precision neuroengineering enables reproduction of complex brain-like functions in vitro

November 14, 2018
One of the most important and surprising traits of the brain is its ability to dynamically reconfigure the connections to process and respond properly to stimuli. Researchers from Tohoku University (Sendai, Japan) and the ...

New brain imaging research shows that when we expect something to hurt it does, even if the stimulus isn't so painful

November 14, 2018
Expect a shot to hurt and it probably will, even if the needle poke isn't really so painful. Brace for a second shot and you'll likely flinch again, even though—second time around—you should know better.

A 15-minute scan could help diagnose brain damage in newborns

November 14, 2018
A 15-minute scan could help diagnose brain damage in babies up to two years earlier than current methods.

New clues to the origin and progression of multiple sclerosis

November 13, 2018
Mapping of a certain group of cells, known as oligodendrocytes, in the central nervous system of a mouse model of multiple sclerosis (MS), shows that they might have a significant role in the development of the disease. The ...

Mutations, CRISPR, and the biology behind movement disorders

November 12, 2018
Scientists at the RIKEN Center for Brain Science (CBS) in Japan have discovered how mutations related to a group of movement disorders produce their effects. Published in Proceedings of the National Academy of Sciences, the ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.