As I suspected it appears they tortured the snails somehow (my guess is electric shock) to create traumatic memories. This has been done with caterpillars I think to see if they retain memories after turning into butterflies and they do, despite basically turning into primordial goop in the cocoon. They do, and it’s tested by seeing if they retain aversions to certain areas of their cages that are electrified.
Then something about enzymes created which associate memory with pain and being able to target them.
Pretty cool, and I for one definitely have a few traumas I’d like erased.