The Inner Workings of Memory

By: Celine Chin



Wikimedia Commons @ James.mcd.nz

Memorization is a big part of everyday life for most people. Studying for that upcoming history test requires memorization and so does learning how to ride a bike. However, the difference between these two things is that studying and learning to ride a bike involve two different systems of memory; studying using the explicit memory system and riding a bike using the implicit memory system. Each memory system processes learned information differently, with different structures in the brain being involved in each.


So first off, explicit memory. It is memory that we are conscious of and the information held within it is meant to be recalled and recited. There are two types: episodic and semantic. Episodic memories contain information from events that have happened in your life as well as information like your name and age. Semantic memories contain information like facts, formulas, and strategies. So how are explicit memories formed and stored in the brain? The first step to formation is encoding, which means that information is processed or recorded within the brain. The memory of this information is formed mainly in the hippocampus, which creates links between neurons and brings together all of the various parts of the memory such as sound, smells, and colours. Once this memory is formed, it becomes easier to recall when it is rehearsed; for example, reciting your history notes over and over will make it easier for you to retrieve information from them when the test comes. Episodic memories can often cause strong emotions to follow as well, with the amygdala in the brain being responsible for this. The amygdala is a brain structure that is highly involved in the experience of emotions. Such emotionally-charged episodic memories may also have an adaptive purpose, like helping us remember dangerous situations because of the fear we feel. When memories are strong enough in the brain, it gets stored long-term in the brain’s cortex; its storage location in the brain is dependent on the type of memory it is and the senses that were involved.


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The second type of memory is implicit memory, which involves remembering things without needing to consciously give it thought. It relies on past experiences in order to create memories. Implicit memory consists of two main subcategories: procedural memory and priming. Procedural memory allows us to remember how to perform various physical activities like riding a bike or brushing your teeth, and makes up the large majority of implicit memories. Priming uses stimuli such as specific words or pictures to guide someone else towards thinking of a future word or phrase. For instance, the word yellow may prime someone to remember a banana and the word red may be used to remember an apple. Two brain structures that are engaged in the formation of implicit memories are the cerebellum and basal ganglia. The cerebellum plays a role in the timing and coordination of voluntary movements, which allows a person to do actions like riding a bike without having to consciously think about it. The basal ganglia is also involved in coordinating a series of motor movements, such as when you play piano or dance. The difference between implicit and explicit memory is that implicit memory often doesn’t require much effort to remember whereas explicit memory often does.


However, some things can also affect the retrieval of our memories; in this case, retrieval is the process of getting information out of long-term storage. For example, we often tend to remember the first and last items of a sequence best, but find it more difficult to remember items in the middle between the two. For example, if you have a list of items you want to buy at the grocery store but forget to bring that list, you might only remember to purchase oranges, apples, brown rice, and beans, which are the first and last couple items. This is referred to as the serial position effect. If only the last items of a sequence are remembered, this is known as the recency effect, while only remembering the first items would be referred to as the primacy effect. Retroactive interference is another thing that can affect memory retrieval. It occurs when new information keeps you from being able to remember older information, whereas proactive interference would be the opposite, with old information affecting your ability to remember the new. We also tend to remember old memories that match our current mood or state; this phenomenon is known as the mood congruence effect. For example, if you’re sad, you’ll remember sad memories, which can often lead into a loop that is hard to break.


Our memories play a big role in our lives, and often can be part of what determines our identity; they allow us to perform various skills and abilities as well as enable us to grow and improve upon ourselves and our knowledge. Ultimately, explicit and implicit memory are extremely important in the endeavors of daily life and are what help create our legacies.



Questions

Q: What are the two types of memory and what brain structures are mainly involved in each?

A: The two types of memory are explicit memory and implicit memory. Explicit memory contains information that is meant to be consciously recalled and remembered, while implicit memory contains information that is remembered on an unconscious level. The hippocampus is mainly engaged in the formation of explicit memories, while the cerebellum and basal ganglia are involved in implicit memory formation.


Q: What are some things that can affect memory retrieval?

A: Some examples of things that can affect retrieval of memories are the serial position effect, the recency effect, the primacy effect, and the mood congruence effect. With the serial position effect, you tend to remember the first and last items of a list. The recency effect refers to the tendency to remember only the last items of a sequence, and the primacy effect refers to the tendency to remember only the first items. The mood congruence effect refers to the tendency for a specific mood to trigger memories that also share the same mood.



Sources

Websites:

https://www.goodtherapy.org/blog/psychpedia/explicit-memory#:~:text=Explicit%20memory%2C%20also%20referred%20to,indirect%2C%20unconscious%20form%20of%20memory.

https://www.livescience.com/amygdala.html

https://www.annualreviews.org/doi/abs/10.1146/annurev.neuro.25.112701.142937?journalCode=neuro#:~:text=Extensive%20evidence%20now%20indicates%20a,or%20habits%20are%20incrementally%20acquired.

https://courses.lumenlearning.com/boundless-psychology/chapter/step-3-memory-retrieval/

https://www.sciencedirect.com/topics/psychology/recency-effect

https://www.betterhelp.com/advice/memory/what-is-mood-congruent-memory-what-can-it-teach-us/

https://www.vanderbilt.edu/olli/class-materials/Neuroscience_April4th.pdf

https://qbi.uq.edu.au/brain-basics/memory/where-are-memories-stored

Images:

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