Dr. Chris Magryta: Learning and memory

Published 12:00 am Sunday, April 19, 2020

We have known for a long time that memory is consolidated during the learning process through repetition and associations that provide context to the memory. The chances are that the memory will persist if the associations are strong and the repetition is frequent. Think of your favorite song. You remember the lyrics 20 years later and often a place and event that was associated. In March’s Scientific American, we see a full analysis of the mechanisms behind this process that demonstrate the plasticity of this event.

We have long known that the brain is separated into white matter and grey matter where the white matter gets its name because of the fatty appearance that is made by the substance known as myelin that covers the long axons to provide a conduction advantage to the nerve’s electrical impulse that goes from synapse to synapse. This can be a long distance outside of the brain. The sciatic nerve travels from the base of the spine to the big toe. The grey matter of the brain is where the neuron cell bodies that initiate the critical electrical impulses that allow us to move and think congregate.

This white matter appearing myelin coating of the axon is at the core of the key piece of learning and memory where it used to be thought of as simple insulation. The research has identified that we have the ability to add or take away the myelin sheath layers as needed based on memory formation.

Let me take a step back. When we make a thought, an electrical impulse is sent from the neuron cell body to the terminal synapse along the axon. When the signal reaches the synapse, neurotransmitter chemicals are released and cross the gap, synapse, to the next neuron where receptors pick them up to initiate the signal onward to its final destination. The myelin that covers the axon speeds up or slows down the impulse’s movement based on the volume of layers that wrap the axon.

The new research has shown us that the oligodendrocyte in the brain which controls the myelin deposition has the ability to regulate the neurological signal speed and thus function by adding layers of myelin to specific axons based on memory needs. When a memory or nerve set is unused, the myelin will be unlayered and the memory will be reduced and ultimately pruned making space for more and newer necessary memories.

This new pathophysiology adds to the known literature that deep sleep stages cull over 80% of synaptic connections based on a lack of need and maintains the ones that are deemed useful long term. See the newsletter below for details. Combine this with the addition of myelin to improve signal transduction and function and we are beginning to see the greater picture. We can significantly improve memory over time through repetitive behaviors like rereading or replaying a song multiple times and attaching an association that makes the event strong in our psyche. Repetition and association are key. Repetition is the route to mastery through myelin development and memory consolidation.