The more we know, the more complex it looks

Images of mouse neurons from the hippocampal region of the brain. Levels of the surface receptor GluR1, orange, are shown in unmodified neurons, left, and in those with increased levels of Tet3, right. Credit: Huimei Yu, Johns Hopkins Medicine

The brain, and not just ours, has always been seen as a tremendously complex machine. As we improve our ways to look at it we get more and more information on its working, however rather than shedding light on the way it actually manages to perform all its diverse activities we pile up more and more questions anf the complexity increases.

We have had interesting results in the understanding of how a brain forms memories and access to them, we understood that memories are about circuits that forms, whose neurones are actually part of many circuits and therefore of many memories, that synapses strengthen their bindings when we learn and when we "store" a memory and so on. All this knowledge has been backed up by experiments and yet the overall understanding of memory formation, storage and retrieval is far from being clear.

As scientists and researchers work on getting more information to finally shed light on this we get more understanding of what is going on but this does not get us any nearer to the goal. It is just making the whole picture more complex, like a fractal. In a fractal picture you see the overall pattern, and then you want to get more details and the result is to have a more complex pattern and so on in a never ending story.

That was the thought I had when reading of a new discovery made by scientists at John Hopkins hospital: neurones involved in memory (and, possibly, many others) do something tricky and potentially dangerous, they change their DNA!

The strengthening of synaptic junctions requires the production of specific proteins and these are controlled by genes in the DNA of the neurone. Genes are blueprint providing instructions to build a protein. These instructions are brought by mRNA into the Endoplasmic Reticulum in the cytoplasm where ribosomes assembled the requires amino acids. A gene contains plenty of instructions and the selection of the right ones is made by regulatory tags attached to cytosine base in the DNA. 

It turns out that the neurone depending on the activities performed (which are the result of signals received by its dendrites) changes these tags thus changing the way proteins will be produced, eventually changing the synaptic strengthening.

Another tile of the puzzle is surfacing but the overall puzzle has just become a bit more complex!

Author - Roberto Saracco
