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Tuesday, October 11, 2011

Smell templates in the brain

According to new research by Christina Zelano and Jay Gottfried of Northwestern University and Aprajita Mohanty of Stony Brook University, our brains may be pre-wired to recognize specific scents.  As we anticipate smelling something, be it a rose or a rotten fish, our brains prepare to compare that odor to a preexisting template.  Once the odor actually hits our nostrils, there’s a strong and immediate match.

The researchers tested this assertion by giving subjects distinctive odors (watermelon and/or Playdoh) while they were in an MRI machine.  The volunteers were first primed to identify one of these two smells, and then given a countdown before the smell was administered. The subjects were told to press a button when they identified the target scent, if present.  If the target smell matched the expectation (they were told to prepare for a watermelon scent and watermelon smell was indeed presented), pre-smell and post-smell scans of the olfactory center of the brain showed greater correlation.  In other words, the subjects’ brains were primed to receive a specific odor.

What could be the advantage of having these ready-to-go scent templates?  The scientists suggest that predictive scent templates can reduce processing time.  They may also allow us to identify smells in smaller concentrations.  Zelano gives the example of being able to quickly determine whether milk is spoiled.

You can see an explanation below:

Sniffing Out the Brain's Predictive Power from Northwestern News on Vimeo.

This study raises some interesting questions that I hope will be addressed.  For one thing, just how many of these templates do we have, and how permanent are they?  Presumably, all the test subjects were already familiar with the scents of watermelon and of Playdoh.  What if they’d been presented with something completely foreign to them?  Or what if the subjects hadn’t known ahead of time what to expect?