I can’t remember what I ate Tuesday but I remember a certain thing my teacher told me in elementary school? Why do I remember that very vividly but I don’t remember something so simple and easy? This leads me to think how my brain processes my memories and how do I store them.

1. The Bakery Model of the Brain

So for starters the brain is not a library of shelves with books labeled “childhood” or “the summer I fell in love.” I think of it as a city full of bakeries, each baking slices of your life. 

Neurons are bakeries, constantly baking loaves of information as we live our lives normally. What we saw, what key things happened ,how we felt and how that feeling affected us are the important information points those neurons bake. As they bake, all the important info points blend in together in the loaf of bread (your full experience) . Like if we think of graduation we usually feel the proudness coming in as well as the polished outfits and smiling faces we saw, the people we said goodbye to and the people we celebrated this event with partying and fun. Without all of it together it will probably feel like a sketch rather than a real experience, especially without feelings we felt that day. So our neurons make our newest memories collecting these information and summing it up as an experience we had. In our brains, the hippocampus and other related structures in the temporal lobe, hold memories like this. In this process I want to also mention the importance of what we felt that day and how it effects the way we process the day. Imagine two people inside a newly opened church late at night. Person A has had a rough day, while Person B has been lucky and cheerful.At the end of their prayers when they are sitting with their own thoughts as they look around they will notice different things. Person A can notice the small cracks and imperfections on the walls or the dimmed lights of the church may make them think of the place as melancholic, Person B on the other hand may notice how the new bouquet of flowers on the side of the wall is real pretty or how the dimmed lights make the place more intimate and aesthetic. So when they want to go to that church again Person A might recall the place as a quiet and sad while Person B will recall it as aesthetic and calming. How they felt that day made them notice different things relevant to their moods so they remembered according to them. Recalling the place connected to the emotion they felt in there might change as they go in there with different feelings but over time the sum of it all will also be remembered by the most-felt emotions they’ve experienced there.

2. Roads of Memory

As we’ve talked about remembering, how exactly does our brain do that one? The (info point of a memory) bread made in the (neurons) bakery is delivered by neurotransmitters, to the certain other (neurons) restaurants only if the restaurant is open (has receptors open to take the transmitted info points in). And if there are no restaurants open, the wandering neurotransmitter gets swiped away with enzymes and enzymes break them down, or transporters suck them back into the neuron they came from for reuse.That’s why neurotransmission is so efficient, it’s not random chaos, it’s a system with recycling built in. Nothing is wasted if possible. Also I want you to think the neurotransmission happens on many roads between streets and bakeries and restaurants; like millions of transmission happening on these roads passed in seconds. So one single exchanging of bread isn’t a full memory but a piece of the whole pattern. A memory = a pattern of bread exchanges happening across thousands or millions of neurons at once. Imagine an entire city where certain bakeries (neurons) always send out bread to the same restaurants (other neurons) when you recall your 10th birthday. Those exact bread pathways firing together leads to that memory. So long story in short, there isn’t a single “drawer” in the brain for “my trip to the beach.” Instead, the sights live mostly in the visual cortex, the smells in the olfactory system, the sounds in the auditory cortex, the feelings in the amygdala, and the timeline/context in the hippocampus.The hippocampus is like a treasurer who remembers how all those bakeries connect.

3.Why Our Braıns Let Go

I’ve also said if we don’t recall enzymes can break the neurotransmitter down or transporters can take them back for reuse  but if all those memories have certain connections in our brains how can we “forget”? So the thing here is we have to get back to the roads that the transmission is happening on.Every time we recall a memory ,especially when the neural pathways are still fresh, neurotransmitters travel the roads between neurons to reconnect the pieces. But over time when the road isn’t used as much (not thinking about or recalling that event) plants grow over the road and eventually cover it up making it unseeable and unusable although it is still there (we forget).

Another interesting thing is usage of that road by synapse of two neurons actually strengthen the road between them, the system upgrades itself with synaptic plasticity like Neuron A can send out bread faster or in bigger batches and Neuron B has more receptors to take in more bread from Neuron A. That’s why active recalling is a used method in studying or memorization , it works when you continue recalling.

Remembering on the other hand is like cleaning the grass out of the road, clearing it up for usage again. And sometimes when we try to remember things we can write out a different story than what have happened because although we can clean the road we may not fully see the original color, the exact lines, or which way it bent:the overgrown grass subtly erases details and our brains just fit random things in to make the story acceptable. And that effects many important things: that’s why eyewitness testimony is unreliable when people remember a crime and get asked leading questions, they unknowingly rewrite details.

As well as rewriting the scene I told you guys about how our emotions also carve the road in different ways, let me give another example. If there is a flood of emotions coming through with a trauma the road gets thicker while it’s getting built. Because those memories get reinforced with chemicals (like norepinephrine, cortisol). They’re thicker, darker, more vivid. You can’t easily cover them with grass again. They’ll stay with you and your vivid memories for a long time, they’ll pop out even when you don’t want them to. And you will connect places or sounds or words with the experience so when you’re hearing the same voice or words or when you’re at the same place you will get “triggered” and recall that trauma unless your brains coping mechanism is erasing your roads and memories.

These changes explain why two people at the same event can remember it differently and why “what really happened” is often disputed.. Imagine two travelers walking down the same road. At first, they see the same scenery: the same houses, trees, smells in the air. But each of them notices different things. One is looking at the flowers on the side, the other is staring at the sky. One is anxious and only notices the cracks on the road; the other is laughing and only remembers the warmth of the sun.

Later, when the grass grows back (forgetting) and they come to clear it (remembering), each traveler restores their own version of the road:

• The flower watcher rebuilds a road with bright colors and blossoms.
• The sky watcher rebuilds one with wide open space and light.

And neither of them remembers the road exactly as it was, only as they experienced it.

Sometimes this leads to wrong explanations of events and creates untrue sides, stories. So when explaining something that’s happened we should acknowledge the objective truths in them first, like the undeniable actions that happened. Not the reason behind them or not how the receiver felt, those are way more complicated to explain fully. 

4. A weırd but cool study on memory

And there is an interesting study on these topics especially how we recall memories in the brain by  Wilder Penfield ( https://pmc.ncbi.nlm.nih.gov/articles/PMC10542740/  ) it is fascinating if you ask me! 

Penfield’s experiments on memory stimulation are both remarkable and somewhat unsettlingly fascinating. What he does basically is: he applies mild electrical currents to specific regions of patients’ brains during awake neurosurgery, finding vivid recollections of their past experiences. Patients reported detailed “flashbacks” ranging from childhood events to long-forgotten daily occurrences.Particularly, stimulation of the hippocampus and medial temporal structures were the most effective in triggering these episodic memories. Penfield took these observations as evidence that memories are stored in a relatively fixed and accessible form within the brain, linking the process to a tape recorder playing back previously recorded material. BOOM. Like HOW can one specific place in the brain activate a whole memory when we know a memory involves millions of transmissions across neural roads?

In Penfield’s case, when he stimulated one area, it was like he hit the main bakery of a neighborhood. Once that bakery starts sending bread, the restaurants it connects to also light up, and suddenly the whole memory-pattern is active. So one electrode didn’t touch a drawer with a whole memory inside. It touched a hub in the network. And because brains are associative (everything links to something else), firing that hub can spread like a domino effect until the full memory pattern replays playing out the experience including visual auditory olfactory and emotional parts of it. (Also some recollections may be reconstructed or over exploited influenced by expectations and context.)

In conclusion, Penfield’s work provides compelling evidence of the brain’s role in memory recall, yet it also underscores the complexity of human memory. But it is kind of intriguing right?