[michaelerule]

I think the point is that there are smells that we do remember for a lifetime, which must be explained. Either these stable memories aren't mediated by the cells in piriform that Schoonover and Fink recorded, or there is a mechanism that supports drifting yet stable distributed representations.

[FeepingCreature]

Or sometimes you get drift, and then you don't remember a smell, and this happens all the time - which is why if we re-smell something, we don't necessarily hit the same neurons, but we also remember old smells, because those didn't drift. Or is that excluded by the experiment?

[michaelerule]

My understanding was that these experiments didn't completely rule out the possibility of a stable sub-population. Also, the olfactory bulb projects to other areas besides piriform, and those might support long-term stability. My extremely speculative unfounded conjecture is that piriform is actually a novelty encoder, and plays a role in encoding new memories in a changing environment. But, I think the data don't quite support this at this time.