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.
Now, we have three broad areas
that we want to talk about.
So the first is sensory memory,
so, the initial recording of the
sensory information coming in.
So you hear something, you see
something, you smell something.
It needs to go somewhere.
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.
This is limited in
duration and capacity
and these aren’t new terms.
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.
things in your long-term
memory will still get lost.
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.
So that is something that’s been
stored in your long-term memory.
Now, chances are you’re not going
to forget that probably ever.
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.
So you still had that for a very
long time, but as you’re 50,
you might not remember
that kind of stuff.
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.
Sensory memory is a really kind of
unique -- is a really unique beast.
It’s something that’s
really in the now.
It’s taking a snap -- we say a snapshot
of what’s happened in that moment,
but it decays extremely quickly.
So you have iconic memory.
So it’s like photographic,
tenths of a second you can
remember exactly what you saw,
but it doesn’t last very long.
And you have echoic memory, which is sound.
An example would be sound.
It can last three to four seconds.
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.
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.
Think of the process of simply
walking down the street.
Okay. Now, you’re walking down the
street, you’re seeing a lot of stuff.
Do you need to actually process
and acquire and memorize
everything that you see?
So think of your brain as a
hard drive and, you know,
you can’t fill in every
piece of information.
It’s going to fill
up and explode.
So you’re going to want to just focus
on the things that are relevant
and keep things to memory
that you really need.
So in that walk, that ten-minute
walk from home to work,
you’re going to see
a lot of things.
You’re going to see stones, the
road, cars, people, shops, birds,
and you’re going to hear a
lot of different things.
In that moment it goes in, you see it,
you process it, and then it’s gone.
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.
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.
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.
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.
We call that the Broadbent
filter in short-term memory.
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.
So think about a sieve that
your drain your spaghetti in.
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.
So short-term memory is
limited in duration,
it doesn’t carry a lot.
So we’re saying on average,
roughly seven items.
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.
So that’s why you get a phone
number and we’ve all done this.
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.
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.
Short-term memory is found and it’s
highly linked to the hippocampus.
This is the structure that
we have mentioned before
and we know that the hippocampus is
highly involved in memory function.
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.
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.
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.
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.
So if your job is to open
up a new type of can.
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.
Now, you got to remember
how to use a can opener.
Okay, check, got that.
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
you being able to actually do
things and coordinate movement.
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.
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.
So the different the types
and what’s happening.
So we have working memory and that as you
can see is dealing with a problem or task.
In either end we
short-term and long-term memory both
feeding into working memory as required.
Now, let’s get into implicit
or procedural memory.
This is a little bit different.
This is where you’ve had
and those experiences assist with the
task without conscious awareness.
So the example that we have
here is how to do a tie.
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.
You can have different triggers that
allow you to do this task quite quickly.
So I’m just thinking of your daily
life, you know, brushing your teeth.
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.
And you’re not thinking really,
it’s just semiautomatic and that is
that implicit or procedural memory.
And you try to get certain
complex tasks to this point
because it makes it easier
and much more manageable.
Now, this is actually a move that a
lot of physicians and surgeons do.
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.
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.
They can do it without actually
having to consciously think about it.
Explicit or declarative memory is when you
make a conscious intentional recollection
of previous experiences
and you’re going to declare
that you’re doing it.
So you declare or
voice what is known.
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.
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.
And where did that come from
or where is that stored?
That’s stored in your
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.
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.
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.
You can pretty much pick and
choose almost any moment
in your life that you have stored
and remember as episodic memory.
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.
We have long-term memory
and that gets broken down into explicit
memory versus implicit memory,
or declarative versus
which means memory with conscious
recall versus without conscious recall.
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.
And then under the implicit, we have
procedural memory of how to do things,
motor skills, actions, quite quickly,
quite easily, and quite accurately.
So do we have some biological evidence
for explicit versus implicit?
And the answer is yes, we
go to our brain structure.
So we know that the hippocampus and the
cerebellum and the amygdala are involved.
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.
And the amygdala usually
brings emotion in,
so we’re saying involved with
associating emotion with memories,
particularly negative emotions.
So if you want to tie
in an emotional memory,
that’s where that’s going to happen.
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.
So the function has been
validated by examining
patients with brain injury
and developing toddlers.
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.
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.
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.
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.
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?
And do you remember the
first time your parents
took you to a zoo when
you were, you know, two?
You don’t remember any of that stuff
because you have infantile amnesia,
you’ll forget all that stuff.
And you don’t typically start
recalling memories until --
well, our memory start roughly around
the three to four-year-old age.
So a little tip for new parents,
don’t do anything for your kids until they’re
four because it’s all wasted, right?