Nose - The Tip of the Smelling Story

Researchers at Cold Spring Harbor Laboratory (CSHL) and Harvard have found that smell is based on more than the neuronal networks that receive various stimuli. Different from vision (that pays attention to edges, shading, brightness, and color), smell is affected by odor molecules and a lot of other intriguing unknowns. 

Odors, good or bad, enter the nose as the front door of the smelling (olfactory) mechanism. Some smells like your breath and sweat are identified as "self" and mostly ignored. (Unless you have been on the tennis court or football field for a heavy workout. Then the usual monitoring gets kicked up a notch and even YOU notice you stink.) 

Other smells set off different neural activity patterns across the brain. 

In mammals, the olfactory bulb has neuronal circuits that process information via receptors. It sends information to higher processing brain areas, including the cerebral cortex. There, smell messages are analyzed thoroughly and sent across the brain (i.e. chocolate=yum or skunk spray=yuck) before they return to the bulb in a feedback loop.

The latest research shows that signaling is linear and is further analyzed in the brain with respect to intensity, known characteristics, and past experience (i.e., banana or mountain lion). Go Science!