How are memories formed?

Don’t forget to remember.

My earliest childhood memory is probably the fire scare at my childhood home. That night, I recall being whisked away by my parents (along with my sisters) out of the house and onto the streets, as the firefighter’s truck swooped in. What a memorable and scary night. Turns out it wasn’t “just a scare” as it did, unfortunately, affect our neighbour’s home. Thankfully, there were no casualties.

I remembered this because there was an actual fire scare at my place of work recently. And long after calm was restored and that memory had resurfaced, it brought up some questions for me.

One was definitely why someone(s) had cooked up that phoney rumour.

But also, how did memories come about anyway? And what about the study that suggests most of our “childhood memories” (before the age of three) are actually fake, even though we believe them so much?

Which, yup. Yikes.

Let’s dive into the world of memories.

Where are memories stored?

Perhaps obvious is the simple fact that the brain stores memories. Sherlock Holmes’ work here is done. But where precisely?

While some have argued that the entire brain is generally involved in the formation and subsequent storage of memories, some areas of the brain have been specifically implicated.

First up is the amygdala.

If that sounds familiar, it’s because we’ve also talked about its role in Why Humans Seem To Focus on Negatives. Don’t we just love a multitalented dude?

Because of its function in processing emotions, such as fear, the amygdala is implicated in memory consolidation. It’s how we remember that it’s probably not a good idea to stick our hand inside fire.

Perhaps most widely accepted, however, is the role of the hippocampus.

Research has shown that damage to this area is involved in Alzheimer’s disease, a condition mostly characterised by progressive memory loss and commoner in the elderly. 

This reminds (hehe) me of the famous story of the man known widely as H. M.

Here’s the short version:

In a desperate attempt to cure his recurrent seizures, a 26 year old man had certain parts of his brain cut off in surgery. But while he did get rid of the seizures, he also got rid of something else. His memories. Or at least his ability to form new ones. The hippocampus had been cut off.

This made it clear that there couldn’t possibly be one singular area responsible for memories. Others that have been discovered include, but are not limited to, the cerebellum (also responsible for precise body movement) and the pre-frontal cortex

Random words: book, xylophone, pepper

On a granular level, however, memories are formed and recalled by the reactivation of the unit of brain cells, the neurons.
So how exactly are memories formed? What informs what we keep and what goes in our mental Recycle Bin? And also, why are some neurons reactivated over others? 

The answer lies in the synapses.

The actual process of memory formation

Synapses are connections between the neurons of the brain. 

The connection between these neurons becomes stronger when they regularly activate one another and weaker when the opposite occurs. The weaker ones might then “decay”, as suggested in the Decay Theory of forgetting. This is one of the theories for why Spaced Repetition works as a study technique.

Sleep helps to consolidate memories.

Memories can then be recalled when specific groups of neurons are activated. This works closely with factors such as strong evocation of emotion (which isn’t surprising since the amygdala is involved in both these processes). Same for reasoning and thinking, thanks to the multiple functions of the prefrontal cortex.

Memories are heterogenous. From the sensory (immediate recall) to the short term/working to the long term memory. From the procedural (such as learning how to ride a bike, for example) to the spatial (navigating through a known city) to the episodic (remembering your first kiss). And there’s still a lot to unravel on memories and their formation.

But one thing’s for sure. Learning to remember things is another art-form of itself.

Like, do you remember what those 3 random words from earlier were?