How You Make Memories and Why You Forget
How You Make Memories
There isn’t much thought given to memory when you are younger. It just seems to happen. If you are in school, you actually work to make memory work for you. But as you get older – and not by a lot – you start to experience memory slips. Now memory is on your mind. Memory actually changes who we are. It becomes the basis of how we view the world and all our experiences. Memory cues the connections between the neurons to change. Our world is then changed. So - what is memory all about? What happens in your brain when you make a memory?
Let’s get the vocabulary of memory on the table first.
Immediate memory: This is a newer term for me but it is actually the very first part of the memory cycle. This is the very first exposure to what might become memory. This input is generally held in the area of exposure – seeing an event is held in the visual cortex; hearing something is held in the auditory processing center and so on. These first attempts at memory are held in these specific areas very briefly because the brain is deciding if this information is worthy of becoming a memory.
Short-term or Working memory: it is hard to recognize short-term/working memory as memory at all. It lasts for only about 15-30 seconds, has very limited capacity and is very vulnerable to distraction. There is a relationship between the senses and memory and putting all of these triggers together occurs within working memory. This is referred to as the consolidation process. This process occurs within the prefrontal cortex of the brain. In the transfer of immediate memory to working memory some of the content is loss. This is mostly interference or distracting information. This is a critical part of the memory process because it makes this whole process very efficient. You would use short-term memory for remembering a phone number from the time you looked it up to the time you dialed but you don’t need to keep this information in memory forever (usually).
Long-term memory: This is how we think of memory. Information throughout our life is stored as long-term memory. Long-term memory has unlimited capacity and is not vulnerable to distraction. Long-term memory can be divided into two categories:
Implicit or Nondeclarative memory: include habits and skills that we can do
automatically – like driving a car.
Explicit or Declarative memory: these are memories we are consciously aware of and trying to remember. And of course, there are two kinds of explicit memory:
Episodic –memory of things and events that happened to you
Semantic – for more general knowledge
Let’s get down to the nitty-gritty of how we make memories. There are three steps in memory making: Acquisition, Storage, and Retrieval. I will actually talk about acquisition more when I talk about forgetting. So information is channeled to the hippocampus (center for new learning and memory). The hippocampus has the monster job of linking the information together and actually encode it into a new memory by forming new synapses. A synapse is the chemical gap between two neurons (brain cells). The hippocampus must determine what information is important enough to be encoded. That is a very important part of the process because we are inundated with massive amounts of information every day. So if we repeated the information enough times in short term memory then the signal is strong and worthy of encoding. If we didn’t get a clear signal – as through hearing loss – the signal is jumbled and is not encoded. The hippocampus prioritizes information that has been practiced repeatedly in short-term memory or information that has emotional content. (Let’s have an ‘aha’ moment here). Emotional memory goes to the top of the encoding order.
You have a memory encoded within a synapse (crazy huh!) and the next step happens. The memory has to go to long-term storage. Newer memories stick around in the hippocampus for awhile. As the process of making new memories keeps happening then, memories move further into the cortex (outer layer of the brain). Memories end up being stored all over the brain. Similar memories clump together – spoken memories are near the language centers, visual memories are near the visual cortex. If you learn through multiple senses, then memories can be redundant and stored in different areas of the brain. Recall becomes more likely because you have greater storage areas involved. Every time you activate a memory, through recall, it becomes stronger.
Last piece of the memory process is recall. What good is it if you have all these wonderful memories and you can’t recall the information. Sort of sounds like neurodegenerative diseases like Alzheimer’s doesn’t it? “Recall is a very impressive but slightly mysterious process. When we want to access a memory from the dark recesses of our brain, signals from our frontal cortex link to that memory via uncertain means, and the memory is reconstructed from the information available. The more you use the memory, the easier it is to find.” (The Guardian, Sept. 16, 2015) I will talk more about recall in the Why You Forget section.
Why You Forget
Notice that this is a declaration – everyone forgets! There are a few perspectives on forgetting – some true, some untrue. Forgetfulness is not a sign of Alzheimer’s disease. It is also not the sole domain of being older. There are many reasons why we forget.
As I mentioned earlier, short-term memory is very vulnerable to distraction. You think you have the information but outside distraction – a TV, traffic, music – might have pulled your attention away from the information you were trying to acquire. You heard it but your brain also recorded all of the other background too. When the signal goes in to be processed, your brain eliminates all signals that aren’t strong and clear. Goodbye memory. You haven’t forgotten it because you never got it in the first place. Attention and repetition are critical for getting that information transformed into memory. Stress and anxiety are also disruptive to forming a memory. Anything that pulls your attention and focus can interrupt the formation of new memories and the recall of old memories.
Here are some specific theories about forgetting:
· Cue-dependent forgetting: We embed memory with certain cues that are available – scents, sounds, visuals. This theory states that the reason the memory is temporarily blocked is because the proper cue is not available to bring it to mind.
· Trace decay theory: If we don’t repeat the information initially, the information will fade away and decay. Repetition causes repeated firings in the brain and holds the memory until structural changes can occur within the synapses.
· Organic causes: This theory states that information held in long-term storage is destroyed and there is no ability to encode new memories. This occurs in Alzheimer’s disease.
· Interference theories: This theory refers to an idea that learning something new causes old information to be forgotten. Encoding new information can be confused with old memories and there is a distortion or disruption of memories. There is some thought that old memories are reorganized with new memories and that none of your memories are exactly how the event or memory occurred.
· Decay theory: This is the use it or lose it theory. When something new is learned, it has to be recalled over time or the memory will decay. Time is the greatest impact in remembering an event.
Aging does have an affect on memory. I am more specific in the article 'The Older I Get, the More I Forget'. For now, know that the best way to create and recall memories is to assign attention and meaning to the input process. Attention will help you capture good, clear signals that the brain can work with to encode. Meaning gives you the emotional component to put that information high on the memory encoding list.
Repeat, Repeat, Repeat – and you have a memory. We can do that!!
References:
Pendick,D. (Feb. 22, 2013). 7 common causes of forgetfulness. Retrieved April 23, 2015 from The Harvard Business Blog, http://ww.health.harvard.edu/blog/7-common-causes-of-forgetfulness-201302225923/print/
Ranrura,A. (Mar. 12, 2013). How we remember, and why we forget. Retrieved September 4, 2016 from http://brainconnection.brainhq.com/2103/03/12/how-we-remember-and-why-we-forget/
The Guardian. (Sept. 16, 2015). What happens in your brain when you make a memory? Retrieved September 4, 2016 from https://theguardian.com/education/2015/sep/16/what-happens-in-your-brain-when-you-make-a-memory