system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why do memories attach so strongly to certain scents?
gpt
Scent is the most primitive of our senses, it is essentially our brain reaching out of our skull (through the cribiform plate at the base of the skull) to chemically sample volatile compounds in the environment. Every other sense is mediated through other organs, transmitted through nerves for the brain to interpret, but not scent. As a result the way that scents are processed and associated with memories is somewhat different to the results of other senses. 

Specifically and not very ELI5: scents are processed in the olfactory bulb and then connected directly to the amygdala and hippocampus, bypassing the thalamus.