In addition to being the sense most closely linked to memory, smell is also highly emotive. The perfume industry is built around this connection, with perfumers developing fragrances that seek to convey a vast array of emotions and feelings; from desire to power, vitality to relaxation.
On a more personal level, smell is extremely important when it comes to attraction between two people. Research has shown that our body odour, produced by the genes which make up our immune system, can help us subconsciously choose our partners — read more here. Kissing is thought by some scientists to have developed from sniffing; that first kiss being essentially a primal behaviour during which we smell and taste our partner to decide if they are a match.
It is likely that much of our emotional response to smell is governed by association, something which is borne out by the fact that different people can have completely different perceptions of the same smell. Despite this, however, there are certain smells that all humans find repugnant, largely because they warn us of danger; the smell of smoke, for example, or of rotten food.
You can read more about his on our page about Dangers. Thus each receptor is not responsible for understanding all possible smells. Those signals are then passed to what are called microregions within the olfactory bulb where again, different microregions specialize in different odors. The olfactory bulb is then responsible for interpreting those signals into what we perceive as smells.
Your olfactory bulb runs from your nose to the base of your brain and has direct connections to your amygdala the area of the brain responsible for processing emotion and to your hippocampus an area linked to memory and cognition.
Neuroscientists have suggested that this close physical connection between the regions of the brain linked to memory, emotion, and our sense of smell may explain why our brain learns to associate smells with certain emotional memories. So many of these odor-driven memories may further be childhood memories because those years are when we experience most smells for the first time.
There is not yet research to suggest that we can tap into the link between scents and memory to help us cram for tests or remember where we put our car keys as adults. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Discover World-Changing Science.
How does our sense of smell work? In the deep recesses of the nose are millions of sensory neurons that, along with our eyes and ears, help conjure the world around us. Different patterns of glomerular activation are known to generate the sensation of specific odors. Firing one set of glomeruli elicits the perception of pineapples; firing another evokes pickles. Unlike other sensations, such as sight and hearing, scientists do not know which qualities of a particular smell are used by the brain to perceive it.
But the ears and nose might be less important in how the brain represents that person. The authors of the new study sought to identify distinguishing features involved in forming the representation of odors in the brain.
To do so, they used a technique called optogenetics to activate glomeruli in mice. Optogenetics uses light to stimulate specific neurons in the brain. And it can help determine the function of particular brain regions. They first trained the rodents to recognize the switching on of six specific glomeruli, causing them to perceive an odor that was unknown to the researchers.
The mice received a water reward when they recognized the correct smell and received water from a spout. When other glomeruli were activated—generating a different odor—there was no reward. This step allowed them to determine how important each glomerulus was to accurately recognizing the smell. A given glomerulus, in effect, acts as its own mini sensory organ within the olfactory bulb. They found that the sequence of glomerular activation was crucial to odor perception.
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