Nostrils
can detect stimuli independently
By
Stephanie Lam
Daily Californian
BERKELEY (U-Wire)—As a rule, human beings are born with a pair of eyes,
a pair of ears and a pair of nostrils. With both vision and hearing, the doubled
sensory organs serve to localize or pinpoint the specific stimuli perceived,
and as researchers from UC Berkeley are discovering, the two nostrils may play
a similar role.
Jess Porter, a graduate student in Berkeley’s biophysics program, associate
psychology professor Noam Sobel, and senior scientist Rehan Khan of the psychology
department recently performed a study along with undergraduate student Tarini
Anand and graduate student Brad Johnson of the bioengineering department, that
showed the nose is able to differentiate between smells entering the left and
the right nostrils.
The study involved working with volunteers, to see if they could identify from
which nostril the smells were coming from. Donning a mask Porter helped design,
which contained a divider to separate between left and right nostrils, volunteers
were presented with an odor in one of the compartments, and asked to identify
which side it came from, with reasonable success.
Magnetic resonance images of the participants’ brains also revealed corresponding
brain activity between which nostril smelled the odor, and where in the brain
the information would be processed.
“We saw that in certain regions greater oxygen would be used while volunteers
were participating in the task, suggesting that the activity involved that region
of the brain,” Porter said. “Across all these regions, the activation
is higher when the subject is correct, confirming that these regions were involved
in doing that job.”
Because odors often have a component of touch as well as smell, like the stinging
sensation that accompanies the ammonia odor, the researchers used both trigeminal
smells, or smells that had such touch sensations, and pure olfactants, or smells
that lacked the touch sensations.
In the future, Porter and Sobel will examine whether the brain is still able
to localize odors when placed in a natural setting.
“This is still really a far cry from bloodhound tracking. That’s
too overstating. This is a brain mechanism that shows a possible area in the
brain that serves as doing left or right localization,” Porter said. |
