The Sense of Smell

The Sense of Smell is the most long-lasting human memory, going back to childhood.


The nerve cells in the human nose responsible for the sense of smell number in the millions and connect directly to the brain.

The winners of the Nobel Prize in medicine in 2004 found that when a particular odor hits a particular nerve cell the protein in the cell changes shape which causes an electrical signal to be sent to the brain.

We know there are many different kinds and shapes of proteins in different nerve cells. Each nerve cell can react to a very few individual odors but because there are millions of these smell (”olfactory”) nerve cells many many different odors can be isolated by the human nose. (The dog's ability to detect odors is at least 100 times the humans. The dog detects people food and environment primarily by odor. The dog has 40 times as many nerve cells for odor as do humans.)

When the nerve cells reach the brain their messages are combined with other nerve cell messages and

the brain says “Oh that is Rose” or “Oh that is skunk” . This part of the brain is called the ‘olfactory cortex’. In medical terms, the brain decodes the messages from the nerve cells.

(Lower 2 diagrams from the Nobel Commission )