Here’s an interesting finding: Miller and Sweatt have demonstrated that DNA methylation (essentially dynamic covalent modifications of genes) plays a crucial role in hippocampal fear conditioning. It’s published in NEURON. I linked to the Faculty of 1000 citation for those who don’t have access to the journal.
The significance is that the genome itself can be modified and essentially serve as an engram. This is a really old idea, but this new wrinkle gives the notion new life.
Jim
Discoverers and Discoveries 