Your Incredible Brain - Memory

To begin this blog, I would like to do a little activity. A simple one at that, but activity nonetheless. I want you to just try and remember what you did yesterday morning. When you woke up, how long it took you to get out of bed, if you ate breakfast, what you ate, etc. Done? You've just activated every single part of your brain and used it at its full capacity to recall, recreate an image of, and put into words what you did more than 24 hours ago. You utilized your amygdala, hippocampus, cerebellum, prefrontal cortex, and more! You should be proud of yourself! Your brain is truly incredible, the topic of this blog. 

First, let's talk about your ability to learn and so-called "muscle memory." Muscle Memory is defined as a form of procedural memory that involves consolidating a specific motor task into memory through repetition (Wikipedia). An example of this could be your morning routine - you get out of bed, take any medicine, brush your teeth, etc. Over time this process just kind of comes naturally, without any effort or brainpower. 

The prevailing theory of the brain's ability to learn and repeat actions is the Dual-Process Theory. The Dual-Process theory basically states that there are two systems that your brain takes advantage of when learning. System 1 is associated with memorization and unconscious thought, while System 2 is associated with critical thinking and active thought. Harvard University has a brilliant paper on it here, as well as how you can use this understanding of memory to learn and teach as efficiently as you can.

The Two Systems of Thought (Source: Harvard University)

When learning a skill at first, such as riding a bike or driving a car, the brain uses primarily System 2 pathways, as it has to critically think about every action that it is taking. However, repeated exposure is the key to turning a System 2 task into a System 1 task. Once something becomes a habit, it can be done unconsciously. This is done primarily through encoding, and there are four main types of encoding. To demonstrate all 4 types, I will be giving examples of driving a car

1.) Visual encoding: How something looks. An example would be a green light meaning go, and a red light meaning stop - as well as knowing what certain things in your car look like, such as the volume knob, the stick, and the window levers.

2.) Acoustic encoding: How something sounds. An example would be the sounds that your car makes when you drive it.  If the car is making a different sound than you have memorized it to make, you know something is up.

3.) Semantic encoding: What something means. An example would be a green light meaning go, a  person in front's blinker meaning they are turning, or a stop sign meaning stop.

4.) Tactile encoding: How something feels. An example would be how the steering wheel feels, how much pressure you need on the gas and brake, and the click of the blinker when you move it.

Safe to say, the brain is incredibly skilled at doing what it needs to do, and it is extremely useful that we do not have to use critical thinking and analysis for every decision that we make at every moment in our lives - that would not be fun.

Now let's talk about another part of memory - long-term memory and more specifically, the feeling known as 'nostalgia.' Everyone has felt it before - you hear a song from your childhood, smell a certain scent of a location long gone by, or simply remember a moment from a long time ago. These types of triggers will cause extreme emotions unlike any other. 

The key to nostalgia is increasing blood flow and metabolic in very specific parts of the brain, most often the frontal, limbic, paralimbic, and mid-brain areas. This increased blood flow fires neurons in which memories are stored and activates the 'reward' parts of the brain - parts like the hippocampus, the substantial nigra, the ventral tegmental area, and the ventral striatum. Read more about it here

Once these reward parts of the brain are activated, dopamine is released in spades. Dopamine has been identified by scientists as a sort of 'happiness chemical.' You'll often see articles about ways to increase your dopamine levels in your brain, and this can basically be translated as 'how to be happier' but with more scientific words. Interestingly, scientists have been able to directly associate dopamine with the memories in the hippocampus. In fact, a lot of dopamine is stored directly in the hippocampus along with your memories, meaning that nostalgia and happiness are directly linked. Read more about it here.

ROI analyses of brain activity for nostalgia vs control events.

This rush of blood into the brain and release of dopamine creates a special feeling of nostalgia when triggered by certain stimuli. My strongest stimuli are typically old songs from my childhood or smells from places that I have not been to in a long time. What are some of your stimuli? We all have them.

So, in short - nostalgia feels so rewarding to us because our brain tells us that it's rewarding. Our brain is such a good leader!