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Types of Memory Storage – Memory (PSY)

by Tarry Ahuja, MD
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    00:01 Memory, let’s talk aboutyou walk with your eye half swollen shut, and you go there and you do this move. types of memory storage.

    00:05 Now, we have three broad areas that we want to talk about.

    00:09 So the first is sensory memory, so, the initial recording of the sensory information coming in.

    00:14 So you hear something, you see something, you smell something.

    00:17 It needs to go somewhere.

    00:19 So that would go into a sort of a sensory memory hold, and there, from there you would have another spot that memory can go to which is short-term memory.

    00:26 This is limited in duration and capacity and these aren’t new terms.

    00:31 You’ve heard short-term, long-term memory before all the time, and long-term like the name implies is where things are going to stay fairly indefinitely, but there is still is some timeline.

    00:41 things in your long-term memory will still get lost.

    00:44 So I if ask you right now to tell me your mother’s name and you can say, you know, “My mother’s name is Veronica.” And so you’re like, okay.

    00:54 So that is something that’s been stored in your long-term memory.

    00:57 Now, chances are you’re not going to forget that probably ever.

    01:01 But if I was to ask you, do you remember the name or the name -- or so do you remember the first color of bike that you had? Okay. So if you’re 50, you might say, “Oh, man, I think it was red.” When you’re ten, you’re like, “It was red, for sure.” So as time has gone on, that memory sort of decayed and it’s not so relevant and you lose it, but it’s still there when you’re ten.

    01:27 So you still had that for a very long time, but as you’re 50, you might not remember that kind of stuff.

    01:31 So my point here is long-term memory is quite long, it can be indefinite, but there’s also situations where you tend to lose things.

    01:39 Sensory memory is a really kind of unique -- is a really unique beast.

    01:46 It’s something that’s really in the now.

    01:48 It’s taking a snap -- we say a snapshot of what’s happened in that moment, but it decays extremely quickly.

    01:54 So you have iconic memory.

    01:56 So it’s like photographic, tenths of a second you can remember exactly what you saw, but it doesn’t last very long.

    02:04 And you have echoic memory, which is sound.

    02:06 An example would be sound.

    02:07 It can last three to four seconds.

    02:09 But both of these, again, they don’t last very long, and the idea is you want it to get in and you’re going to very quickly make some decisions.

    02:16 Is this going to my working memory, is this going to go to my short-term memory, is this going to go to my long-term memory, what am I going to do with this? And if it’s not relevant, if you don’t need it, it’s going to be gone.

    02:25 Think of the process of simply walking down the street.

    02:29 Okay. Now, you’re walking down the street, you’re seeing a lot of stuff.

    02:32 Do you need to actually process and acquire and memorize everything that you see? Well, no.

    02:39 So think of your brain as a hard drive and, you know, you can’t fill in every piece of information.

    02:44 It’s going to fill up and explode.

    02:46 So you’re going to want to just focus on the things that are relevant and keep things to memory that you really need.

    02:51 So in that walk, that ten-minute walk from home to work, you’re going to see a lot of things.

    02:56 You’re going to see stones, the road, cars, people, shops, birds, and you’re going to hear a lot of different things.

    03:03 In that moment it goes in, you see it, you process it, and then it’s gone.

    03:06 So if asked you 15 days ago what color of shirt did you see on the guy that walked by you at the three-minute point of your walk? Well, I don’t know. There was some guy -- I don’t even remember the guy.

    03:19 It’s because in the moment, as you’re walking by, you saw the guy and you said, “Oh, red shirt,” and you kept walking.

    03:24 And within -- by the time you even got to the office you probably don’t remember that, because you weren’t consciously saying, “Red shirt.” It just kind of was going in and it gets lost.

    03:34 So info from sensory memory decays quite quickly, we mentioned that already, and it passes through this filter and I was kind of eluding to that.

    03:41 We call that the Broadbent filter in short-term memory.

    03:44 And what happens is if it goes through that filter, it will stay, and if it doesn’t go through that filter, it’s lost So what’s important, what do we want, and, you know, the idea of a filter is to allow certain things through while blocking other things.

    03:58 So think about a sieve that your drain your spaghetti in.

    04:01 The water all goes through and the spaghetti does not, okay? So in this scenario let’s say that the memories that we want to keep is the water, it’s going to go through the sieve and the spaghetti gets blocked out and then you end up throwing the spaghetti, okay? Because you don’t want that, you don’t need it.

    04:14 So short-term memory is limited in duration, it doesn’t carry a lot.

    04:19 So we’re saying on average, roughly seven items.

    04:22 So it can be a little bit more, it can be a little less based on how good your memory is, and it’s sort of retained for about 20 seconds, so not very long.

    04:30 So that’s why you get a phone number and we’ve all done this.

    04:33 How many times have you done this? You see an ad on TV and you’re like, “Okay, remember that number,” and you’re quickly trying to remember and just as you’re trying to grab the phone and dial, you forget some of the numbers and you’re like, “Oh, my God. What’s wrong with me? I can’t remember this number.” That’s because you really don’t have a lot of time and you really can’t remember a lot of numbers.

    04:52 So let’s take a look at short-term versus working memory because we’ve already mentioned working memory before, and the two are related, but they are different.

    05:01 Short-term memory is found and it’s highly linked to the hippocampus.

    05:06 This is the structure that we have mentioned before and we know that the hippocampus is highly involved in memory function.

    05:13 So it’s a portal into long-term memory and if it doesn’t get into long-term memory, it’s very quickly going to get lost.

    05:19 So, it comes in, it’s going to go to working memory, it’s going to get to the short-term memory and if you don’t save it and file it away in your long-term memory -- it’s gone.

    05:30 And working memory is strongly correlated with the prefrontal cortex, so now we’re talking two different regions, hippocampus versus the PFC, and it is an area, like I said, where a lot of executive function happens, where you’re doing things.

    05:42 So it kind of makes sense that that memory would be -- be held in an area that’s doing those types of functions, right? So it’s considered a storage bin for holding both short-term and long-term memory, so it’s a mixing pot because it’s there to allow you in that moment to do a specific task.

    05:57 So if your job is to open up a new type of can.

    06:04 So you went and got this soup and the soup comes in this new can and you’re going to use working memory to open up that can.

    06:11 Now, you got to remember how to use a can opener.

    06:14 Okay, check, got that.

    06:15 That will be in the long-term memory. But then you got to remember, “Okay, I got to put my hand here and I got -- I got to work it this way and I got to hold it like this.” So it’s involving executive function, you being able to actually do things and coordinate movement.

    06:25 These are all things that are typically done by the prefrontal cortex and you need memory of, you know, what is a can opener? How do I use a can opener? That’s long-term memory. That’s getting put into this mixing pot of working memory.

    06:38 So my point here is I’ve drawn into different memories in order to achieve and accomplish the task at hand, which is why it kind of gets that name of working memory.

    06:46 So the different the types and what’s happening.

    06:49 So we have working memory and that as you can see is dealing with a problem or task.

    06:54 In either end we have short-term, short-term and long-term memory both feeding into working memory as required.

    07:02 Now, let’s get into implicit or procedural memory.

    07:04 This is a little bit different.

    07:06 This is where you’ve had previous experiences and those experiences assist with the task without conscious awareness.

    07:12 So the example that we have here is how to do a tie.

    07:17 So you typically don’t sit there and work through all the different steps of how to tie a tie, especially if you do it on a daily basis, you just kind of look in the mirror and it’s done.

    07:27 You can have different triggers that allow you to do this task quite quickly.

    07:35 So I’m just thinking of your daily life, you know, brushing your teeth.

    07:38 You know that your condition association is you get up in the morning, you walk with your eye half swollen shut, and you go there and you do this move.

    07:45 And you’re not thinking really, it’s just semiautomatic and that is that implicit or procedural memory.

    07:51 And you try to get certain complex tasks to this point because it makes it easier and much more manageable.

    07:58 Now, this is actually a move that a lot of physicians and surgeons do.

    08:02 You, being an MCAT studier hoping to be a doctor one day, this is probably something that will apply to you, and that’s, you want to take a very complicated task that requires lots of facets of memory and automate this.

    08:16 So what physicians and surgeons will do and is they’ll repeat a task over and over and over and over so that it becomes literally automatic or procedural.

    08:24 They can do it without actually having to consciously think about it.

    08:31 Explicit or declarative memory is when you make a conscious intentional recollection of previous experiences and information and you’re going to declare that you’re doing it.

    08:39 So you declare or voice what is known.

    08:41 So if I’m asking you to say something or recall something, you got -- you have to -- you have to say it. It’s quite obvious, right? So two subdivisions include your semantic memory and episodic memory and this is where you are sort of reciting specific things, and we’ll go through some more examples so this makes sense.

    09:00 So semantic memory is memory for factual information and what is -- like for example, if I say to you what is the capital of Canada and you’re going to see this Canadian flag.

    09:08 And where did that come from or where is that stored? That’s stored in your semantic memory.

    09:14 Now, on the other hand, episodic memory consists of the storage of recollection of life events, right? And we say it allows for mental time travel.

    09:23 But if I’m asking you, do you remember that field trip you took when you were in grade five? “Oh, yeah, yeah, we went to go see the trees and it was really neat and I had a good time and we saw the bears,” and you can recall all those things.

    09:34 And then we basically have this running story of our life, which is why we’re saying you can go mental time travel within a few words of me pointing you in the right direction or even me not saying anything.

    09:44 You can pretty much pick and choose almost any moment in your life that you have stored and remember as episodic memory.

    09:54 So let’s take a look at this overall diagram which is going to show you all the different aspects that we’ve talked about so far.

    10:00 We have long-term memory and that gets broken down into explicit memory versus implicit memory, or declarative versus non-declarative, which means memory with conscious recall versus without conscious recall.

    10:12 Then we have within explicit, we have episodic, where these are things that you’ve -- an episode or a memory that you’ve gone, you’ve experienced versus semantic, which is straight up facts.

    10:22 And then under the implicit, we have procedural memory of how to do things, motor skills, actions, quite quickly, quite easily, and quite accurately.

    10:31 So do we have some biological evidence for explicit versus implicit? And the answer is yes, we go to our brain structure.

    10:39 So we know that the hippocampus and the cerebellum and the amygdala are involved.

    10:42 So the hippocampus is associated with explicit memory, which is the encoding of new explicit memories, which is how you remember that type of memory versus the cerebellum and amygdala, which is where you’re doing things like learning skills and conditioned associations.

    10:57 And the amygdala usually brings emotion in, so we’re saying involved with associating emotion with memories, particularly negative emotions.

    11:03 So if you want to tie in an emotional memory, that’s where that’s going to happen. Okay? So again, we’re looking at the different type of memory and we’re aligning that with different types of brain structures, which gives us biological evidence for the differences.

    11:18 So the function has been validated by examining patients with brain injury and developing toddlers.

    11:22 So again, I’ve mentioned this before, a lot of ways that we understand how the brain works and how we understand behaviors is by looking at pre and post-trauma or injury because it allows you -- unfortunately, sometimes invasively, the impact that a structure might have.

    11:38 So we know that if there’s been hippocampal damage that you have -- you have troubles forming and storing new explicit memories, right? So that allows us to validate the idea that we have up above in the table.

    11:51 We also can look at little kids in the areas where the hippocampus isn’t fully evolved, or we have structures that are still developing, those features of memory have not already been set up.

    12:03 So infantile amnesia is when little kids, little babies do all these fun things and you take all these pictures and you take them to all these wonderful places, and sad to say, but by the ages of three to four, anything that’s happened from three to four or younger essentially gets lost.

    12:20 And so, if I ask you right now, do you remember your favorite color of pajama or your favorite blankie when you were one year old? Noo And do you remember the first time your parents took you to a zoo when you were, you know, two? No.

    12:34 You don’t remember any of that stuff because you have infantile amnesia, you’ll forget all that stuff.

    12:38 And you don’t typically start recalling memories until -- well, our memory start roughly around the three to four-year-old age.

    12:45 So a little tip for new parents, don’t do anything for your kids until they’re four because it’s all wasted, right?


    About the Lecture

    The lecture Types of Memory Storage – Memory (PSY) by Tarry Ahuja, MD is from the course Making Sense of the Environment. It contains the following chapters:

    • Introduction of Types of Memory Storage
    • Sensory Memory
    • Short-term vs. Working Memory
    • Implicit or Procedural Memory
    • Explicit or Declarative Memory

    Included Quiz Questions

    1. Short term memory
    2. Long term memory
    3. Sensory memory
    4. Episodic memory
    5. Implicit memory
    1. Broadbent filter
    2. Short term memory
    3. Subliminal threshold
    4. Iconic memory
    5. Echoic memory
    1. Implicit memory
    2. Explicit memory
    3. Declarative memory
    4. Long-term memory
    5. Iconic memory
    1. Semantic memory, episodic memory
    2. Episodic memory, semantic memory
    3. Explicit memory, Implicit memory
    4. Implicit memory, explicit memory
    5. Iconic memory, echoic memory
    1. Iconic memory
    2. Echoic memory
    3. Short term memory
    4. Working memory
    5. Declarative memory
    1. Prefrontal cortex
    2. Hippocampus
    3. Frontal lobe
    4. Amygdala
    5. Temporal lobe
    1. Declarative memory
    2. Implicit memory
    3. Procedural memory
    4. Long term memory
    5. Semantic memory

    Author of lecture Types of Memory Storage – Memory (PSY)

     Tarry Ahuja, MD

    Tarry Ahuja, MD


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