Why do smells trigger such powerful memories?

The answer

The powerful connection between smell and memory, known as the Proust phenomenon, has an anatomical basis. The olfactory bulb, which processes smell, has direct neural connections to the amygdala (emotional processing) and hippocampus (memory formation), bypassing the thalamus relay station that other senses pass through. This direct pathway means odor information reaches memory and emotion centers faster and with less filtering than visual or auditory input. Brain imaging studies show that smell-triggered memories activate the amygdala and hippocampus more strongly than memories triggered by the same cues presented visually or verbally. Odor-evoked memories tend to be older (typically from the first decade of life), more emotional, more vivid, and more strongly associated with feelings of being 'brought back in time' compared to memories triggered by other senses.