Memory and smell

[Added March 2000]
Does the sense of smell improve learning?The other day I had the following
experience. From time to time I do “experiments” on memory by learning a
list of ten items. If I start in the evening , it will
take usually a few rehearsals and for the following morning the list is perfectly
memorised. This time, when I was starting the exercise, going through the list
for the first time, something happened. An electrical appliance misbehaviour produced a smoke with a pungent scent of melting plastic. The problem was quickly
fixed but the smell was still present after many hours. I discovered also
that my learning of the list was a lot faster and I could use, the following
morning, the smell to recall it!

Initial detection of odours occurs in the nose in the olfactory epithelium. The epithelium contains millions of odour molecule specific neurons that
make direct physical contact between the external world and the brain. When a certain odor is detected it causes certain neurons to fire in the olfactory bulb
. The olfactory bulb then sends a signal to the olfactory
cortex and then on to the Limbic system for further processing and memory recall. The information goes to the thalamus (part of the Limbic system) but also
,in case of smell and taste, to the amygdala and hippocampus(also part of the
Limbic system). This gives smell (and taste) powerful memory stimulating properties that can explain what I experienced.The Limbic system is referred as the
“seat of emotion” and is basically an information storing and processing system.The hippocampus ,for example, serves to recall simple, short-term memories stimulated by sensory input.These memories are spatial. The amygdala can ,instead,
evoke memories connected to emotion.In fact, removal of hippocampus will produce
short term memory failures. Removal of amygdala will produce emotionless aggressive behaviour in monkeys.So,it seems,that by using some smell during
learning, we are in fact storing our memories using still another track. This
will improve both the process of learning and recall.
Here is an interesting document on the subject.