Tim Hines brought this article from MIT News covering activity-induced double-stranded breaks in neurons to our attention:
And here's the abstract in Cell of the reference paper:
Additionally, Mike Wyatt followed up on this as well:
"Post script to the May presentation about modified cytosines. This paper offers pretty good evidence that 5-formyl cytosine is a distinct epigenetic signature, not merely an intermediate going from 5-mC or 5-hmC back to unmodified cytosine."