Re: Do odorrs effect your moods?

Dear Morgan,

The olfactory system is perhaps one of the least understood among sensory 
systems. One striking characteristic of the olfactory system is that it is 
much more developped in inferior animals. If you look at olfactory bulbs 
(where the olfactory information is first processed) in the rat brain, you 
will find that they are quite large with respect to the whole rat brain. 
On the other hand, olfactory bulbs in human are relatively small. 
Nonetheless, early views of the limbic system (collection of several brain 
structures that are believed to be involved in emotions) have given an 
important role of the olfactory system as a major sensory input to the 
limbic system. Moreover, studies strongly suggest that many regions of the 
limbic system are also involved in memory processes. To my opinion, this 
makes sense because we tend to retain events that have emotional content 
rather than those which have not. Although some authors have shown that 
specific limbic structures are involved in emotions but not in memory 
processes as it was previously suggested (see Squire LR.  Zola-Morgan S., 
Science.  253, pp1380-6, 1991), it remains that the olfactory system has 
neuronal projections from olfactory bulbs to regions identified as very 
important in memory (i.e. entorhinal cortex ; see figure below).

To answer your question, I would say that YES, I believed that odors can 
influence our feelings. To illustrate my position, I will tell you an 
example. Imagine a child who, each sunday, goes to visit his grandmother who 
makes very good soup which makes the whole kitchen smell very good. Suppose 
that the child has now became an adult and did not visit his grandmother for 
many years. The person then goes in a house where a cook has made a similar 
soup which also produces a similar smell. At this moment, the person may 
experience a strange feeling, reminiscent of his interior state when 
he/she was a child visiting his/her grandmother. Although this remains 
speculative, we can postulate that the olfactory information has been 
preserved in brain regions together with events (and emotional states) 
experienced at this time and that, even longtime after, these emotions can 
be triggered by the same (or very similar) olfactory input. This example 
can be compared to the feeling we get when we hear a song that we were 
listening to when we were younger.




Hope that helps,
Eric