Memories fade..but something remains

This isn’t a statistics post–it’s about Bob’s neuroscience research. 

Most long-term memories are ‘forgotten’–meaning that recall becomes less and less likely.  Psychologists have long known, though, that forgetting is complex, and that fragments of a memory can remain.  For example, even after a memory seems forgotten it can be easier to re-learn the same material, something called ‘savings memory’.  That suggests that there is at least some fragment of a memory that persists in the brain even after it seems forgotten…but what?

Today our lab has published a paper shedding a bit of light on this long-standing mystery (Perez, Patel, Rivota, Calin-Jageman, & Calin-Jageman, 2017).  We tracked a sensitization memory in our beloved sea slugs. As expected, memories faded–within a week animals had no recall of the prior sensitization.  Still, the memory wasn’t completely gone because we found that a brief reminder could rekindle the memory.  Even more exciting, we found similar fragments of memory at the molecular level–there was a small set of genes very strongly regulated by the original training even though recall had fully decayed.  Why?  We don’t know–but this is an exciting first glimpse of the molecular correlates of a ‘forgotten’ memory.

There is a bit of a New Stats angle here.  We used microarray to screen for regulated genes–but we screened for both statistical and practical significance (by testing against a null that represents a real minimum of interest rather than just exactly 0). Then we used direct replication with a new sample and a more sensitive technique to confirm all the genes we believed to be regulated.  All results were reported with effect sizes and CI (though we did let some beastly p values into the paper, too).

Update: Ushma’s artwork for our paper was selected and is now on the cover of the February issue of Learning and Memory.  Here’s the actual cover: