Regulation of memory storage through epigenetic alterations: a new role for RNA

A fundamental assumption in modern psychology and neuroscience is that memory is stored as physical changes in the brain. More than a century ago, the famous neuroanatomist Ramón Y Cajal (see the article entitled “Santiago Ramón y Cajal, the ultimate scientist?” in this issue of The Biochemist) postulated that changes in the strength of synaptic connections between neurons were the physical substrate for memory. Extensive experimental evidence has since established the dominance of this connectionist view, referred to as the “synaptic plasticity” model. However, although the synaptic plasticity model broadly accords with the results of neurobiological studies of learning and memory, it does not fully account for the extraordinary resilience of memory despite the significant loss of synapses during such phenomena as development, trauma and ageing. Here, we will focus on the newly discovered role of small non-coding RNAs (ncRNAs) as potential master regulators of learning-induced epigenesis, neuronal plasticity and, ultimately, memory. In support of this idea, recent data from our lab indicate that RNA can promote the transfer of long-term memory from a trained to an untrained (naïve) animal.