We smell with our brain...

Extending from the multitude of nerve cells in the olfactory mucous membrane are numerous appendages – processes – that are bundled in the upper nasal cavity in the
form of nerve fibers. These nerve fiber bundles extend through the
ethmoid plate, a bone behind the root of the nose, and into a part of the brain that is called the olfactory bulb. If subjected to strong shear forces such as those caused by a heavy blow, for example, this bone can slice through the bundle
of nerve fibers like a knife – resulting in a loss of the sense of smell.
In the olfactory bulb, each of these hundreds of nerve fibers, which serve as a continuation of the nerve cells with their olfactory cilia, terminates in an olfactory brain cell. Following pre-selection here, the stimuli are then advanced to portions of the midbrain and to the so-called olfactory brain.The olfactory brain was one of the earliest portions of the cerebrum to develop, which in turn is linked with the limbic system, the system that controls our feelings and emotions. Interestingly enough, nerve impulses do not travel in only one direction – this area also contains nerve cells that work in the opposite direction. This means that there
are a variety of ways in which a kind of feedback can modulate and modify the way a scent is perceived. Consequently, the expectations of the person who is smelling can exert a strong influence on the way a scent is experienced – yellow is associated with freshness, red with fruity sweetness. If this expectation is not fulfilled,
the scent is frequently rejected, even though it is not really unpleasant. So a product’s olfactory acceptance is also highly dependent upon the right kind of packaging!

The intensity of a scent, too, can influence its acceptance. This is because not every stimulus that is triggered by a molecule actually reaches the brain. The number of molecules that are necessary for this to happen (which is termed the olfactory threshold) depends upon the fragrance material in question. In highly concentrated form, fragrance materials are often perceived as pungent. In this case,
the nose would appear to be overstimulated – molecules are also deposited on the “wrong” receptors, thus triggering olfactory confusion, a “blurry” smell. In diluted
form, on the other hand, they seem delightfully floral or fruity! A floral
fragrance would have to be diluted to 2 to 5% to equal the strength of its natural counterpart. The sense of smell addresses both our emotions and our intellect. A scent’s stimuli are advanced to the right half of the brain, where it is recognized, while intellectual activity or the ability to associate a name occurs in the left half. This explains the phenomenon of being able to precisely identify a scent but not its name. Aromatherapy utilizes the emotional side of our sense of smell and employs essential oils to produce a calming effect, e.g. through lavender oil, or to stimulate the mind, e.g. with citrus oils. Scents can also be used as a source of subconscious manipulation. In Japan, for example, it is not infrequent for essential oils to be distributed through the air conditioning system in order to promote alertness and concentration on the job at hand or to help employees relax during their breaks.