New insights into the molecular basis of memory

New insights into the molecular basis of memory

The brain still harbors many unknowns. Basically, it is assumed that it stores experiences by altering the connections between brain cells. This ability to adapt – which is also called “plasticity” – provides the basis for memory and learning, which is the ability to draw conclusions from memories. On a molecular scale these changes are mediated by modifications of expression of specific genes that as required strengthen or weaken the connections between the brain cells.

The scientists stimulated long-term memory in mice, by training the animals to recognise a specific test environment. Based on tissue samples, the researchers were able to discern to what extent this learning task triggered changes in the activity of the genes in the mice’s brain cells. Their focus was directed on so-called epigenetic modifications. These modifications involve the DNA and DNA associated proteins.

The researchers found modifications, both of the histones as well as of the methylation of the DNA. However, histone modifications had little effect on the activity of genes involved in neuroplasticity. Furthermore, they not only discovered epigenetic modifications in nerve cells, but also in non-neuronal cells of the brain.

Their observations suggest that neuroplasticity is to a large extent regulated by DNA methylation. Although this is not a new hypothesis, the study provides an unprecedented amount of supporting evidence for this. Thus, methylation may indeed be an important molecular constituent of long-term memory. In such a case, methylation could be a sort of code for memory content and a potential target for therapies against Alzheimer’s disease. This is an aspect that we specifically want to focus on, in further studies.