Human noses 'can detect danger'

[Snowy Owl]

Human noses 'can detect danger'

Our noses can quickly learn to link even subtle changes in smell with danger, claim scientists.

http://news.bbc.co.uk/2/hi/health/7318673.stm​

Volunteers who could not differentiate between two similar smells found they could do it easily after being given a mild electric shock alongside one.

Brain scans confirmed the change in the "smelling" part of the brain.

The US research, published in the journal Science, suggests our distant ancestors evolved the ability to keep us away from predators.


It warns us that it's dangerous and we have to pay attention to it.
Dr Wen Li
Northwestern University, Chicago

The 12 volunteers were exposed to two "grassy" odours, and none of them could accurately tell the difference between them.

After they were shocked while smelling one of them, they developed the ability to discriminate between the two.

Researcher Dr Wen Li, of the Feinberg School of Medicine, Northwestern University, in Chicago, said: "It's evolutionary. This helps us to have a very sensitive ability to detect something that is important to our survival from an ocean of environmental information.

"It warns us that it's dangerous and we have to pay attention to it."

Complex organ

MRI scans, which can measure brain activity, revealed clear differences in a part of the brain called the olfactory cortex before and after the shocks.

Dr Geraldine Wright, from the University of Newcastle has carried out similar work in animals - and says that fundamentally, the human smell system is designed in the same way.

She said that the sensitivity of the human nose was not vastly inferior to many other creatures.

"In terms of the number of olfactory receptors in our noses, we do pretty well compared to some other species, and we can sense a lot of different smells.

"If the brain has to remember some detail in order to avoid a bad outcome, it will do it pretty quickly."

Snowy's comments

When you spend many hours, in all seasons, year after year in the Wilderness, this warning system of the smell is very obvious for all animals that you have the priviledge to observe.

Few centuries ago First Collectivities Warriors in the Americas where tough on how to use this odor, even more, it was told in our Oral Tradition, and I have exoerience it many time, that a particular taste come to the mouth that means on guard ready to fight or fly.

I am getting convince that the bee colony crunch we are face with is at least in some portion to the smell within the Bee's house , that would explain there swift runaway.

JMHO

Snowy

 

[tropical]

Re: Human noses 'can detect danger'

"I am getting convince that the bee colony crunch we are face with is at least in some portion to the smell within the Bee's house , that would explain there swift runaway."

Hi Snowy,

I hope times would not comes where we must wear an el. shock device ...

Obviously it is exact that all creatures have similar abilities, but concerning your above doubt, see my today posted text about the new research in relation of bee/insect disorder and polluted air.

t.

 

[gsgs]

Re: Human noses 'can detect danger'

instead of giving electric shocks, they could maybe
ofter bananas or such as reward for correct smelling ;-)

I mean, out anchestors probably mainly used smelling to
locate food rather than to avoid danger

 

[tropical]

Re: Human noses 'can detect danger'

I agreed with you gsgs about the bananas,
it is knowed as the Pavlov efect.

In the stone era probable they smell the tigers, and other dangers also.
But now, we are in the same position of the bees: the polutants ruined our nose interior enaugh to force us to take shocks to sniff natural things from a distance that is not a plate on a table.

 

[Snowy Owl]

Re: Human noses 'can detect danger'

Science 28 March 2008:
Vol. 319. no. 5871, pp. 1842 - 1845
DOI: 10.1126/science.1152837

REPORTS

Aversive Learning Enhances Perceptual and Cortical Discrimination of Indiscriminable Odor Cues


Wen Li,1* James D. Howard,1 Todd B. Parrish,1,2 Jay A. Gottfried1,3,4

Learning to associate sensory cues with threats is critical for minimizing aversive experience.

The ecological benefit of associative learning relies on accurate perception of predictive cues, but how aversive learning enhances perceptual acuity of sensory signals, particularly in humans, is unclear.


We combined multivariate functional magnetic resonance imaging with olfactory psychophysics to show that initially indistinguishable odor enantiomers (mirror-image molecules) become discriminable after aversive conditioning, paralleling the spatial divergence of ensemble activity patterns in primary olfactory (piriform) cortex.

Our findings indicate that aversive learning induces piriform plasticity with corresponding gains in odor enantiomer discrimination, underscoring the capacity of fear conditioning to update perceptual representation of predictive cues, over and above its well-recognized role in the acquisition of conditioned responses.

That completely indiscriminable sensations can be transformed into discriminable percepts further accentuates the potency of associative learning to enhance sensory cue perception and support adaptive behavior.


1 Cognitive Neurology and Alzheimer's Disease Center, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
2 Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
3 Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
4 Department of Psychology, Northwestern University, Evanston, IL 60208, USA.

Read the Full Text at
http://www.sciencemag.org/cgi/conten.../319/5871/1842
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