Figure 1.

Aplysia were trained with electrical shocks delivered to the tail. The training produced long-term (>24 h) sensitization of the snail defensive withdrawal reflex. RNA was then extracted from the nervous system of the trained snails and injected into untrained, naive, snails. The defensive withdrawal reflex was enhanced in the naive recipients. Other snails that received injections of RNA from untrained donor snails did not subsequently exhibit enhancement of the reflex. Additional evidence from the study supports the idea that the RNA from the trained donors induced memory-like changes in the behavior of the recipients via an epigenetic change, DNA methylation. (Image courtesy of David Glanzman, UCLA.).