In the last section we were talking about some early
models of memory and primarily the Atkinson and Shiffrin model. In this
section we examine a variety of different brain structures that are involved
with memory. So let’s talk about a few of these and get an idea about where
they are and what they do.
The first major structure that’s involved with memory is
what is called the Hippocampus, and the Hippocampus plays a major role in
encoding and storing information. When you damage the Hippocampus, you have
problems with storing and recall. Tenerally the information is not
appropriately coded due to insufficient types of elaboration. Thus, when you
damage your Hippocampus (by a stroke or trauma) new information is not
stored. However, your old information remains intact. This is called
anterograde amnesia and often occurs with individuals who experience a
stroke. They’ve damaged their Hippocampus and can’t remember new stuff but
their old information still there. So, when they’re out wandering around
after getting out of the hospital or they’re moved to a new facility. What
happens when they get out on the street and they’re driving around? Where do
they go? Well, they go back to their old place where they used to live.
Now the second type of structure that’s involved with memory is shown on
slide three and is called the Thalamus. The thalamus is also involved with
memory formation. This structure is thought to initially give the message to
print the message that you’re trying to remember. With damage, you never get
memory traces. They’re never created. So the memory that you have is in
neither in short term memory or long term memory. Basically; it never even
gets there.
So, as we see in slide four, when you damage the
Hippocampus, the memories form but due to elaboration problems, it’s not
properly encoded and so it goes away. But with damage to the thalamus, the
memory never gets formed at all.
The next major structure that we want to talk about with
memory is called the Cerebellum. The cerebellum is extremely important for
different types of physical memories and procedural memories. The classic
study that shows this done by Thompson. What Thompson did was he conditioned
an eye blink response and a leg movement response. He then lesioned the area
that disrupted the eye blink response. As a resultt, the leg response was
unaffected. But then he moved to the system of one millimeter closer to the
middle of the brain and then lesions. As a result, he found that the leg
response was affected but the eye blink response was not.
Thus what you seem to have, says Thompson (and others as
well), are specific systems and specific locations where you store different
types of memories that are associated with physical pathways. So, as we see
on slide six, we have isolated procedural memories that have unique pathways
in the cerebellum. You also get the same kind of response when you remove
the Hippocampus and other structures.
The next structure that’s highly involved with memory, is
your cortex and it has lots of different locations that are related to
memory. Where the memory is stored tends to be related to the type of memory
that’s involved. For example, movement memories and things like that tend to
be involved with the precentral gyrus in the frontal lobe of the brain.
Whereas sensory memory items tend to be involved with the postcentral gyrus
located in the parietal lobe of the brain. But mostly when we talk about
memories for knowledge and other things, we talk about structures within the
frontal lobe, and association cortex within the frontal and temporal lobes.
So again, memory is located in lots of different places within your cortex.
It depends upon the type of memory that you are trying to memorize.
Now the last slide that we see here (slide eight), kind of
puts this all together. So let’s walk through the slide so we get an idea
about the different structures that are involved with each aspect of memory.
This is the same figure that we saw earlier in the last section. So, again
we have some sensation and we get some kind of sensory memory. We then pay
attention to that. Now two structures that pay attention to that. The first
is the reticular activating system which basically helps to focus attention.
The second is the thalamus, which we’ve already talked about. So the
thalamus is basically going to develop some kind of memory trace, and the
combination of both structures puts that information into short term memory.
Within short term memory, we are processing information.
If we’re going to store that memory into long term memory, the Hippocampus
takes that memory in short-term memory and converts it into long-term memory
located in your cortex.
So, if we damage any one of these particular systems,
whether the reticular activating system, the thalamus, the Hippocampus, or
the cortex, we have particular types of memory problems. As a result, the
neurologist or the neuropsychologist can examine what’s going on and get a
pretty good idea about brain damage that you have within the system. So, a
variety of brain systems are involved with memory and each of these are
very, very important.
In the next section, we’re going to be talking about
another aspect of memory and these are what are called depth of processing
models, so until that time, we hope that you enjoy your day.
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