Featured Research

from universities, journals, and other organizations

Odors classified by networks of neurons

Date:
May 10, 2010
Source:
Friedrich Miescher Institute for Biomedical Research
Summary:
Scientists in Switzerland are unraveling how odors are processed by the brain. As they report in a new study, odors in the olfactory brain are classified into groups represented by discrete activity states of neuronal circuits. Using advanced optical methods, they discovered that gradual variations in odors result in abrupt transitions between patterns of neuronal activity. These findings provide fundamental insights into the brain's information-processing mechanisms.

Trajectories show the dynamics of neuronal activity patterns evoked by morphing two similar odors (blue to green) in the zebrafish olfactory bulb.
Credit: Image courtesy of Friedrich Miescher Institute for Biomedical Research

Scientists at the Friedrich Miescher Institute for Biomedical Research (FMI, part of the Novartis Research Foundation), are unraveling how odors are processed by the brain. As they report in Nature, odors in the olfactory brain are classified into groups represented by discrete activity states of neuronal circuits. Using advanced optical methods, they discovered that gradual variations in odors result in abrupt transitions between patterns of neuronal activity. These findings provide fundamental insights into the brain's information-processing mechanisms.

A sommelier has no difficulty in discriminating between lime, peach and apricot aromas, hints of cinnamon and cedar, or blackberry and cherry notes in the bouquet of a fine wine. For those with a less discerning nose, such subtle differences are difficult to detect. At the same time, however, the sommelier will not perceive a relatively weak background odor, such as perfume. This is because, from the flood of sensory inputs, the human brain extracts certain information and screens out inessential stimuli so as to produce a well-defined perception.

This was the starting point for the study by a team of FMI researchers led by Rainer Friedrich, published in the latest issue of Nature.

Discrete representation of similar odors

Rainer Friedrich's group investigated how the brain responds when an odor is gradually varied. This involved either altering the concentration of a given odor or "morphing" one odor into another similar one. They observed the activity of cells in neuronal circuits of the olfactory bulb, the first center for the processing of olfactory information in the brain.

In zebrafish experiments, the FMI neurobiologists showed that patterns of neuronal activity were largely insensitive to changes in odor concentration. But the situation was quite different when the odor itself was changed: initially, a change in the molecular identity of an odor had little effect, but at a certain point the activity pattern switched, producing a new odor representation. In this abrupt transition, certain neurons were inactivated while others were activated. The pattern of neuronal activity thus represented the odor in a discrete fashion. The researchers concluded that, in the olfactory bulb, different odors are specifically classified and represented by clearly defined neuronal network activity states. These experimental results support theoretical models which neurobiologists have been seeking to confirm for some time.

Decision making also shaped by discrete perceptual categories

The neurons and circuits of the brain have to perform a tricky balancing act: as well as being able to detect minimal changes in sensory input, they are required to disregard what is not important. We should recognize the lime note in the wine but ignore the perfume worn by the person sitting next to us at the wine-tasting event. Neurobiologists have therefore assumed that sensory inputs within a certain range are classified and processed in the same manner. However, this also means that a minimal change in sensory cell activity can abruptly lead to a different classification if it exceeds the defined range. This has now been demonstrated by Friedrich's group for odor representation. But the same principle may also be operative in other brain processes -- for example, when we make decisions. Here, too, a small item of additional information or one further impression may often be all that is needed for us to change our mind. Rainer Friedrich, Senior Group Leader at the FMI, comments: "We believe that discrete classification of odors by neuronal circuits reflects a fundamental information-processing strategy which is also likely to be relevant for other brain functions."


Story Source:

The above story is based on materials provided by Friedrich Miescher Institute for Biomedical Research. Note: Materials may be edited for content and length.


Journal Reference:

  1. Jörn Niessing, Rainer W. Friedrich. Olfactory pattern classification by discrete neuronal network states. Nature, 2010; DOI: 10.1038/nature08961

Cite This Page:

Friedrich Miescher Institute for Biomedical Research. "Odors classified by networks of neurons." ScienceDaily. ScienceDaily, 10 May 2010. <www.sciencedaily.com/releases/2010/04/100426081237.htm>.
Friedrich Miescher Institute for Biomedical Research. (2010, May 10). Odors classified by networks of neurons. ScienceDaily. Retrieved August 1, 2014 from www.sciencedaily.com/releases/2010/04/100426081237.htm
Friedrich Miescher Institute for Biomedical Research. "Odors classified by networks of neurons." ScienceDaily. www.sciencedaily.com/releases/2010/04/100426081237.htm (accessed August 1, 2014).

Share This




More Health & Medicine News

Friday, August 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Texas Quintuplets Head Home

Texas Quintuplets Head Home

Reuters - US Online Video (Aug. 1, 2014) — After four months in the hospital, the first quintuplets to be born at Baylor University Medical Center head home. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Patient Coming to U.S. for Treatment

Ebola Patient Coming to U.S. for Treatment

Reuters - US Online Video (Aug. 1, 2014) — A U.S. aid worker infected with Ebola while working in West Africa will be treated in a high security ward at Emory University in Atlanta. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Vaccine Might Be Coming, But Where's It Been?

Ebola Vaccine Might Be Coming, But Where's It Been?

Newsy (Aug. 1, 2014) — Health officials are working to fast-track a vaccine — the West-African Ebola outbreak has killed more than 700. But why didn't we already have one? Video provided by Newsy
Powered by NewsLook.com
Study Links Certain Birth Control Pills To Breast Cancer

Study Links Certain Birth Control Pills To Breast Cancer

Newsy (Aug. 1, 2014) — Previous studies have made the link between birth control and breast cancer, but the latest makes the link to high-estrogen oral contraceptives. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins