Featured Research

from universities, journals, and other organizations

Why humans don't smell as well as other mammals: No new neurons in the human olfactory bulb

Date:
May 24, 2012
Source:
Karolinska Institutet
Summary:
The human olfactory bulb – a structure in the brain that processes sensory input from the nose – differs from that of other mammals in that no new neurons are formed in this area after birth. The discovery is based on the age-determination of the cells using the carbon-14 method, and might explain why the human sense of smell is normally much worse than that of other animals.

Research from Karolinska Institutet in Sweden shows that the human olfactory bulb -- a structure in the brain that processes sensory input from the nose -- differs from that of other mammals in that no new neurons are formed in this area after birth. The discovery, which is published in the scientific journal Neuron, is based on the age-determination of the cells using the carbon-14 method, and might explain why the human sense of smell is normally much worse than that of other animals.

Related Articles


"I've never been so astonished by a scientific discovery," says lead investigator Jonas Frisén, Tobias Foundation Professor of stem cell research at Karolinska Institutet. "What you would normally expect is for humans to be like other animals, particularly apes, in this respect."

It was long thought that all brain neurons were formed up to the time of birth, after which production stopped. A paradigm shift occurred when scientists found that nerve cells were being continually formed from stem cells in the mammalian brain, which changed scientific views on the plasticity of the brain and raised hopes of being able to replace neurons lost during some types of neurological disease.

In the adult mammal, new nerve cells are formed in two regions of the brain: the hippocampus and the olfactory bulb. While the former has an important part to play in memory, the latter is essential to the interpretation of smells. However, owing to the difficulty of studying the formation of new neurons in humans, the extent to which this phenomenon also occurs in the human brain has remained unclear. In this present study, researchers at Karolinska Institutet and their Austrian and French colleagues made use of the sharp rise in atmospheric carbon-14 caused by Cold War nuclear tests to find an answer to this question.

Carbon-14 is incorporated in DNA, making it possible to gauge the age of the cells by measuring how much of the isotope they contain. Doing this, the team found that the olfactory bulb neurons in their adult human subjects had carbon-14 levels that matched those at the atmosphere at the time of their birth. This is a strong indication that there is no significant generation of new neurons in this part of the brain, something that sets humans apart from all other mammals.

"Humans are less dependent on their sense of smell for their survival than many other animals, which may be related to the loss of new cell generation in the olfactory bulb, but this is just speculation," continues Professor Frisén.

Professor Frisén and his team now plan to study the extent of neuron generation in the hippocampus, a part of the brain that is important for higher cerebral functions in humans. This present study was made possible by support from the Tobias Foundation, the Swedish Research Council, the Swedish Foundation for Strategic Research (SSF), the American Brain and Behaviour Research Foundation (NARSAD), the Swedish Brain Fund, the Knut and Alice Wallenberg Foundation, AFA Försäkring, the EU and the Stockholm County Council through its ALF agreement with Karolinska Institutet.


Story Source:

The above story is based on materials provided by Karolinska Institutet. Note: Materials may be edited for content and length.


Journal Reference:

  1. Olaf Bergmann, Jakob Liebl, Samuel Bernard, Kanar Alkass, Maggie S.Y. Yeung, Peter Steier, Walter Kutschera, Lars Johnson, Mikael Landén, Henrik Druid, Kirsty L. Spalding, Jonas Frisén. The Age of Olfactory Bulb Neurons in Humans. Neuron, 2012; 74 (4): 634 DOI: 10.1016/j.neuron.2012.03.030

Cite This Page:

Karolinska Institutet. "Why humans don't smell as well as other mammals: No new neurons in the human olfactory bulb." ScienceDaily. ScienceDaily, 24 May 2012. <www.sciencedaily.com/releases/2012/05/120524092222.htm>.
Karolinska Institutet. (2012, May 24). Why humans don't smell as well as other mammals: No new neurons in the human olfactory bulb. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2012/05/120524092222.htm
Karolinska Institutet. "Why humans don't smell as well as other mammals: No new neurons in the human olfactory bulb." ScienceDaily. www.sciencedaily.com/releases/2012/05/120524092222.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Christmas Kissing Good for Health

Christmas Kissing Good for Health

Reuters - Innovations Video Online (Dec. 22, 2014) — Scientists in Amsterdam say couples transfer tens of millions of microbes when they kiss, encouraging healthy exposure to bacteria. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Brain-Dwelling Tapeworm Reveals Genetic Secrets

Brain-Dwelling Tapeworm Reveals Genetic Secrets

Reuters - Innovations Video Online (Dec. 22, 2014) — Cambridge scientists have unravelled the genetic code of a rare tapeworm that lived inside a patient's brain for at least four year. Researchers hope it will present new opportunities to diagnose and treat this invasive parasite. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Touch-Free Smart Phone Empowers Mobility-Impaired

Touch-Free Smart Phone Empowers Mobility-Impaired

Reuters - Innovations Video Online (Dec. 21, 2014) — A touch-free phone developed in Israel enables the mobility-impaired to operate smart phones with just a movement of the head. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Earthworms Provide Cancer-Fighting Bacteria

Earthworms Provide Cancer-Fighting Bacteria

Reuters - Innovations Video Online (Dec. 21, 2014) — Polish scientists isolate bacteria from earthworm intestines which they say may be used in antibiotics and cancer treatments. Suzannah Butcher reports. Video provided by Reuters
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:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

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