"Now that I do know it, I shall do my best to forget it."

topic of the day 056 & video of the day 050

What if you never forget anything?

Youtube channel: It's Okay to be Smart

"Our ability to forget like our ability to remember is a complex and finely tuned mechanism."

What, who, when, how, why? Then, so?

There is no one place in our brain that serves as our memory bank.

Individual memories are scattered all over, many brain cells and several different regions work together to make one memory.

For example: a memory of eating grandma's apple pie might involves some brain cells to help you remember what it looks like, the smell of the cinnamon and the delicious taste, to name a few.

In reality though, a memory isn't a physical thing that you can find in a any given brain cell.

It's an action, not an object.

Think of fans in the stadium doing a wave (you know, the Mexican wave). No single fan is the wave.

The magic only happen when all the fans are together and doing their things in a specific order.

In the same way a memory only happens when many connected neurons fire in a specific pattern.

Because the same cell can fire in many unique patterns, one group of neurons can encode multiple memories.

This increase the memory storage capacity of the brain.

A group of cells called hippocampus is the reason we can remember at all.

A patient with the initials H. M. in 1953 underwent a surgery for epilepsy that demolished most of his hippocampus and he suffered a specific type of amnesia, unable to form new memories or facts or events but could still remember anything he learned before the surgery, showing hippocampus' role in making memories.

How do experience become memories?

Looking into the brain of a mouse in a maze, we can kind of draw a map, showing which brain cells are active while the mouse experiencing something. Later, we can see its brain cells firing in the same patterns, to replay the experience in fast forward over and over, backwards and forwards, to make the connections between cells stronger. This is called consolidation and this is how animals including humans could commit new memories into long term storage. As time passes by, a smell might trigger the same patterns themselves firing again to recall the maze's memories, just like how smelling cinnamon might trigger the memory of apple pie for you.

But the brain's way of creating memories isn't foolproof as sometimes our mental replays of something we imagine can feel as vivid as real experience. If you picture all the sights, smells and sounds of a crime scene from someone's description, you actually activate the same brain network as if you've had been there. That's why leading questions by detectives can inadvertently plant a false memory in a witness.

We are able to remember a lot but we forget even more.

Some forgetting just happens but our brain also forget on purpose.

When a memory fades over time, it's called passive oblivescence. This may happens because the connections between brain cells gradually weaken over time or the memory is still there but you might lose the triggers i.e. sight and sounds you need to retrieve it. The memories could theoretically last forever but when the same neurons get used in other memories, this interference disrupt the original memory. 

Target forgetting happens at night when we sleep, clearing up random useless tidbits that we learned during the day and erase outdated memories. Your brain needs to purge contradictory ideas of Earth being round instead of a flat disk, hopefully choosing the correct one to dispose of. In certain stages of sleep, we trim and prune connections between cells and erase unneeded memory circuits.

The third type is motivated forgetting when an individual intentionally suppresses unpleasant memories. Forgetting on purpose is a way to regulate our emotions, to focus on what needs to be done in the present instead of being lost in negative memories in the past. We may need this to maintain our self image, confidence, remain optimistic and maintain relationship with the ones who hurt us.

Forgetting allows us to move past traumatic life events, as PTSD may be a problem when people remembers too much. Forgetting also lets us clear out junk. Imagine every sight, sound, smell and piece of information your brain processes every day. If our brain didn't sweep out the garbage every night, you would soon overflow your neural network with random and useless trivia.

Unforgetfulness is called hyperthymesia with a US patient, Jill Price, for example suffering from being able to recall everything but being haunted by upsetting memories and regrets by being able to remember every choice she made and how it turned out is not a blessing but rather a curse.

"Being able to forget is just as critical."