If you have wondered why particular smells can bring back vivid and terrifying memories, scientists could have the answer.
They think our sense of smell becomes much more active when we are scared, our nostrils learning to become an early warning system.
New research suggests smell receptors at the top of the nostrils go into overdrive when they detect certain odours.
American scientists think our sense of smell becomes more active when we are scared and our nostrils become an early warning system. They believe sensory cells learn to associate some smells with fear - even before the message has reached the brain
American scientists think sensory cells learn to associate some smells with fear - even before the message has reached the brain.
The researchers, from Rutgers University in New Jersey, developed the new theory after testing the brain activity of mice.
They used electric shocks to implant fear memories associated with particular smells.
When the same odours were wafted towards the mice again the smell receptors became four times as active.
Dr John McGann, author of the paper published in the journal Science, suggested the results will transform the way neurologists think about smell.
He said scientists had previously assumed that sensory organs - including the eyes, nose and ears – are simply detectors, and the brain works out what the messages mean.
Dr McGann said the research could be used for treatments for anxiety disorders such as post-traumatic stress disorder (illustrated), in which senses including smells can trigger an attack
‘In the old model the eye is like a camera, the ear like a microphone, the nose like a chemistry lab, and the job of the brain is to analyse this information,’ Dr McGann said.
The new research, however, suggests that smell sensors adapt independently of the brain, increasing their activity when they first detect the ‘scary’ smells.
The findings suggest that senses act as a ‘warning signal’ for dangerous situations, even before they reach the brain.
Dr McGann added: ‘In this study we watched the activity of the very first neurons of the mouse olfactory system - which controls the sense of smell - and found to our surprise that the activity of those cells not only indicated what odours are present in the nose but also increased their response when the mouse learned that a particular odour predicted they would receive an electric shock.
The new research suggests that smell sensors adapt independently of the brain, increasing their activity when they first detect the 'scary' smells. The findings hint that senses act as a 'warning signal' for dangerous situations, even before they reach the brain
‘This is surprising for two reasons - first, because it shows that the sensory system was incorporating information about the emotional value of specific odours at the input to the brain before the brain had a chance to interpret it.
‘Second, because we tend to think of learning as something that happens deep in the brain after conscious awareness, but the new data show that even the earliest neurons in the sensory system can be changed as a result of learning.’
Dr McGann said the research could be used for treatments for anxiety disorders such as post-traumatic stress disorder, in which senses including smells can trigger an attack.
Neurologists think that smells trigger memories because the olfactory nerve, which carries messages from the nostrils to the brain, is located very close to the amygdala and hippocampus, the areas of the brain connected to emotional memory.
Read more: http://www.dailymail.co.uk/sciencetech/article-2522696/You-CAN-smell-fear-Aromas-bring-bad-memories-sense-active-frightened.html#ixzz2nIGdj2XZ
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