For the first time in history, neuroscientists are observing memory formation and transmission around the brain of a mammal. Developing on advances in the field of RNA research, this astounding discovery really does reveal how this particular function of the brain might work.
Memory is a complex cognitive process comprising many different facets. Before we have a memory (that which we can reconstruct) it has to be encoded in the brain in some way. This is an ever-changing process that is not entirely understood but what we do know is that an initial phase of encoding must take place; this can involve visual, auditory, olfactory perception and more, with a system of storage following its receipt.
This need to store the memory leads to the alteration of molecular structures in the brain including synapses – think of them as radio antennas, one transmitting a particular signal that needs to hop across a gap to another which is designed to receive it; both synapses and radio signal can be strengthened and thus make the job of bridging the gap easier. Memories on a cellular level are seen to be encoded and stable when long-lasting synaptic connections occur between neurons that are in contact with each other. But how do we see this work? Neurons are minute, despite there being 86 billion of them – a figure arrived at by Dr. Suzana Herculano Houzel of the famous ‘brain soup’ study – they are difficult to see and their processes even more troublesome to appraise.
Researchers at Albert Einstein College of Medicine in Yeshiva University developed a mouse model within which they were able to fluorescently tag molecules of RNA (mRNA) that code for beta-actin (β-actin) proteins. This is a process that we have used before to tag particular types of neurons in the brain; you might also remember a similar technique being used to produce a fluorescent pig! The appeal of this technique is in the fact that one can tag beta-actin proteins without disrupting the normal cellular processes within them. Bet-actin proteins are found thought living organisms with large concentrations in the brain.
One study describes a process where Dr. Park stimulated neurons in the hippocampus (memory associated) of the mouse, producing glowing beta-actin mRNA molecules which they were able to observe travel within the dendrites of the neuron. A second study by graduate student Adina Buxbaum observed that the way in which beta-actin mRNA is synthesised and controlled by neurons may be unique, leading to a process where it is packaged making it inaccessible for making protein and subsequently unpackaged making it available of beta-protein synthesis.
Dr. Singer in whose laboratory this was discovered remarks: “This observation that neurons selectively activate protein synthesis and then shut it off fits perfectly with how we think memories are made.” This would allow for selective stimulation of beta-actin protein where and when needed in order to strengthen synapses and in turn, memories. I only wish my synapses were sufficiently strengthened when taking Japanese language classes: transmission of language through auditory and written media and rehearsal of what is heard leading to better retention and reproducibility, all through the effective functioning of our neural circuitry.
To find out more about the molecular basis of memory please click the links cited within text for academic research articles.
Video courtesy of Albert Einstein College of Medicine