How do things such as fleeting experiences, catchy melodies and abstract concepts transform into physical globs inside of our brain?
At the neuroscience level, we know that the intangible idea of memory is centered around physical nerve cells in the brain called neurons, which communicate with each other through electrical and chemical signals. Our current level of understanding is that memories are formed through the synaptic connections between these neurons. The more connections, the stronger the memory. Previously that is as far as we’ve gotten memory-wise because neurons are so fragile that any microscopic probing disrupts the whole encoding-storing-retrieving memory process.
But researchers at the Albert Einstein College of Medicine of Yeshiva University have recently been able to witness a memory being formed at the molecular level as it happens. Using advanced imaging techniques, Dr. Robert Singer and his team at the Department of Anatomy and Structural Biology have finally penetrated the elusive layer between the intangible memories and their previously only indirectly observed processes.
Using a mouse model, the researchers were able to zoom in and image a memory in the making without disturbing the neurons by “tagging” the molecules believed to be crucial for memory development, called messenger RNA (mRNA). When activated, these molecules create beta-actin protein — an essential protein for making memories.
By stimulating neurons from the mouse’s hippocampus, the Yeshiva researchers watched in amazement to see the fluorescently tagged, newly-formed mRNA molecules glowing in the neuron’s nucleus and traveling outside of the nucleus towards the receptive ends of the neuron called the dendrites, where they produced the beta-actin protein and strengthened the synaptic connection.
But how do the neurons know how much beta-actin protein to make? The team also discovered that the mRNA molecules make the special protein for just a few a minutes, enough time to strengthen the connection before the mRNA suddenly return to dormancy.
The team’s findings strongly support the general theory of how memories are formed: when a memory encoded in a group of neurons is activated frequently, the mRNA responds by frequently producing beta-actin protein that strengthens the connections and thus strengthens the memory. The researchers’ brief but shocking video has sent tremors through the scientific community and the fascinated populace as it is the first video of a memory being made and strengthened at the molecular level.