The impulses combine in the olfactory nerves and are carried to the olfactory bulbs.
The olfactory bulbs process the specific combination of impulses into smells.
From the bulbs, the smells travel to the amygdala, hippocampus, thalamus, and neocortex, where they are processed, put into your consciousness, and stored in memory.
Many times, people experience a phenomenon where a signal sniff can trigger a memory from their childhood. This is because smell is the closest sense related to memory.
Smell is processed in the olfactory bulbs which are part of the limbic system of the brain. This area contains the amygdala and hippocampus, which process emotion and memory.
When olfactory bulbs are stimuled, the neurons in the hippocampus and amygdala can be too, triggering strong memories and emotions.
"How Smells Trigger Memories." YouTube. N.p., 20 July 2015. Web. 22 Apr. 2017. .
"How to Master Your Sense of Smell - Alexandra Horowitz." YouTube. N.p., 09 Jan. 2017. Web. 22 Apr. 2017. .
"The Smell Report." The Smell Report - The Human Sense of Smell. N.p., n.d. Web. 22 Apr. 2017. .