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SciTech Talk: The brain makes bouquets smelly

By MIKE YAMAKAWA | September 27, 2013

SMELL AND STRESS

Roses are usually red, and violets are always blue. But can their pleasant smells be changed by a biological cue? It seems that our olfactory system does interpret smells differently during various situations. Loosely speaking, if one is in a very high-stress situation, a nice, rosy smell in a garden could suddenly smell like a closet filled with sweaty pairs of running shoes.

Evolutionarily speaking, the olfactory system is among the oldest of senses, shared by ancient invertebrates and other animals seemingly unrelated to humans. Our smell has provided us with the evolutionary advantage of being able to sense danger, like fire, or being able to tell when food is rotting. It may seem like our nose may not be the most sensitive of sensory organs, as we do not consciously smell the air around us (unless some french toasts are being served in the dining room).

Nevertheless, our brain is constantly processing the stimuli innervating the nerves in our nose. The brain can also sense the slightest change in stimuli, like a waft of slightly burnt french toast instead. The way in which smell is intrinsically linked to emotions or how our mindset can affect our sensory interpretation has not been well established.

Recently, however, researchers found that smell can be severely affected by stress. Wen Li, a professor at University of Wisconsin-Madison Waisman Center, reported that as he showed people photos of car crashes, war and other distasteful pictures, the they found that the imposed stress can actually rewire the brain to make emotion and olfactory centers of the brain process stimuli different.

Through functional MRI testing, which enables clinicians to observe the activity of the brain in real time, they found that what usually two independent circuits in the olfactory and emotional centers of the brain, fuse into one large connection during situations of high anxiety. While the smell of fresh laundry is usually pleasant, if displeasing emotions get in the way, it could smell like worn, bathroom rags instead.

Who knows, maybe this means that the happier you are, the better everything smells in the world!

 

COMPUTER BRAIN

Our brain of course is more than just smell. We pride ourselves with our unparalleled intellect, compared to other animals, and constantly use it to our advantage to survive. Even when we are placed in a completely unfamiliar situation, our brain is able to evaluate, albeit not always correctly, the best behavior or action to take to attain the best result.

For example, if a janitor is told to clean tabletops instead of the chalkboard, they will deduce, without the requirement of understanding the nature of chalk or dust particles or surfaces, that they could probably use the wet towel to wipe the table as well.

Reflecting from these experiences and using modern brain-imaging equipment, researchers were able to find that our brains rely on computer-like mechanisms to handle these situations. We use a similar method that computers use, called the “pointer” system, in which pointer commands are used to look for information stored somewhere as a variable.

The study included a very simple example using sentences. They examined how the brain interprets sentences when unfamiliar words are used. “I want to desk you,” was a sentence that they tested on subjects. We know that desk is clearly a noun, but are able to deduce from sentence structure that it is being used as a verb. While the use of “desk” as a verb is unprecedented, our “pointer” leads us to the “verb” variable, allowing us to interpret the sentence in a familiar way.

 


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