How Memories are Made

December 26, 2022

How Making Memory Works - Silent Synapses

Sitting down to a Holiday Dinner with your family? What a memorable event! Want to make sure you remember it? You need filopodia, or silent synapses. This MIT study has just unpacked a huge mystery, how we learn and keep those memories.

Your brain has some 600 trillion - 4 quadrillion synapses, links between neurons. Each neuron is like a computer chip, connected to some 3,500 -4,000 other neurons by long, slender wires called axons with a synaptic endplate. That synapse is where the electrical impulse that travels down the axon is converted into a chemical message through neurotransmitters that are secreted in little packets into the space between the two neurons called the synaptic cleft. We now know that plasmalogen lipids make up some 70% of the membranes of the synapse. Plasmalogen lipids are the only membrane lipids that can shape-shift, allowing the vesicles filled with neurotransmitter to merge with the endplate of the synapse and disgorge their contents into the synaptic cleft. That's how neurons work. Memories are composed of complex webs of neurons utilizing thousands of synapses between them.

This column reported earlier this year on a study from Yale where a novel imaging technique demonstrated that the density of synapses correlates with cognitive function. This validates Goodenowe's research that shows the loss of plasmalogens is predictive of cognitive decline and mortality. You lose plasmalogens, you lose synapses. Your brain shrinks. You lose memories. We call that Alzheimer's.

What's the reverse? How do we make memories? Ah! That's what this study showed. In mouse brains, using a novel method of examining one synapse at a time, the researchers at MIT were able to approximate that roughly a third of synapses (in mouse brains) are actually immature, "filopodia" that are not yet active. They are just out there, waiting to be activated. They already have NDMA receptors in them, but not AMPA receptors. For a synapse to work, it must have both. They start as tiny little branches called dendrites off of axons that are everywhere in the brain in great numbers, as much as 30% of the brain content. You don't want a mature synapse to be altered by new inputs because you want old memories to stay preserved. But you do want a new memory to make a link, and then to be reinforced and made more durable on exposures. That's exactly what this model allows. Very elegant.

www.What will Work for me. This study explains the means and methods of how memory can be built and maintained. The adage, "Learn something new every day" makes sense when you see it in the context of keeping your brain making new memories and reinforcing those immature, early links into more mature, secure links. And to do that, it has to have means and mechanisms for making those links. The primary building blocks are sufficient plasmalogens to build the membranes and sufficient methylation capacity to manufacture neurotransmitters and pump them down axons. That's B12, B6, and folate. The Bs. And finally, you need choline, choline, choline. Eggs and liver. And then you have to have the willingness to expose yourself to the new event. Push yourself to do something new. It's the number one attribute of "super-agers".

References: Nature, MIT News, Yale News, CNBC,

Pop Quiz

1. What is a synapse?                          Answer: The link between two nerve cells.

2. How many do you have?                      Answer: Between 0.6-4.0 quadrillion. Lots

3. What are synapses composed of?                     Answer: Their walls of made of plasmalogen lipids and inside they have packets (vesicles) of neurotransmitter.

4. What is a filopodia?                     Answer: A tiny, immature branch off an axon with partial formation for a synapse, waiting for a new memory to be formed and for it to be activated.

5. What percentage of synapses of mouse brains are made of filopodia?                   Answer: Some 30%

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