Transcript Biological factors ppt

Long-term Memory
Explicit Memories
(fact-based info, conscious
retrieval)
Semantic
memories
(memory of
facts)
Episodic
memories
(events)
Implicit Memories
(not consciously retrieved)
Procedural
memories
(how to do
things)
Emotional
memories
(memory of
emotional
content)
CLO #7: Explain how
biological factors may affect
one cognitive process.
(SAQ)
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Brain localization: Certain brain structures are
responsible for certain types of memory
functions
Brain structures that affect memory can be
studied through animal studies, case studies
(brain damaged patients) and brain-imaging
technology
Much is still unknown about how memory is
organized in the brain due to the brain’s
complexity and difficulties in studying the
working human brain.
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In the 1990s Kandel studied the sea snail
aplysia. He picked it because it was a simple
organism. He found that STM and LTM result
in synaptic changes in the neural network.
His research showed that learning (forming
memories) means growing new connections or
strengthening connections between neurons.
Kandel went on to study synaptic changes due
to memory in the hippocampus. In other
words, what changes occur in the
hippocampus when new memories are
formed?
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Review: Animals have been studied in
memory research experiments like the Rat
Maze Study. Researchers lesion (cut away
brain tissue) in certain parts of the brain until
the animals cannot perform the memory task
anymore.
Obviously, this cannot be done in humans, so
instead we rely on case studies of people who
already have damage to a certain part of the
brain.
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Clive, an eminent English musician, was in his
mid-40s when he was struck by a brain
infection (herpes encephalitis). He was left
with a memory span of only seconds – the most
devastating case of amnesia ever recorded. In
fact he had:
 Anterograde amnesia (failure to store
memories after a trauma)
 and Retrograde amnesia (failure to store
memories that have occurred before trauma)
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His episodic memory and some of his semantic
memory were lost.
His procedural memory was still intact.
He could not transfer new info into LTM.
His ability to perceive new sensory info was
unimpaired (but faded fast)
He can still play the piano and conduct music
that he learned before his illness (this is implicit
memory).
His emotional memory is intact (eg. He still
loves his wife)
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MRI scanning showed damage to Clive’s
hippocampus and some of the frontal
regions. This indicates that retrograde
amnesia can be tied to the hippocampus
ALSO
Implicit Memory must be linked to a
structure other than the hippocampus.
HM suffered a traumatic head injury when
he was 9 years old. He suffered from
epileptic seizures, but at the time (1950s)
there was no drug treatment for the
seizures. The doctors decided to perform
surgery and remove tissue from parts of the
temporal lobe including the hippocampus.
After surgery he could recall info acquired
early in life, but was unable to form new
memories.
He could hold a normal conversation, but
could not recognize faces of people who
visited him regularly.
He could read and reread the same
magazine without recognizing it.
He suffered from anterograde amnesia.
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In 1997, HM was put into an MRI
and the areas of his brain that were
damaged in the operation were
identified.
The damage was pervasive, but it
did include the hippocampus,
amygdala, and other areas close to
the hippocampus.
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Based on the work of Kandel and Case
Studies like Clive Wearing and HM, the
hippocampus appears to have an
important role in the formation of
explicit memories.
Both Clive and HM had damage to the
hippocampus yet could not form explicit
memories, however both could form
implicit memories.
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The amygdala seems to have a role in storing
emotional memories.
According to one neuroscientist, LeDoux,
certain memories have emotional significance
which explains why memories based on
emotional events are remembered better.
It also explains why people suffering from
post-traumatic stress disorder have problems
forgetting emotional memories.
CLO #10: Discuss the
use of technology in
investigating cognitive
processes (Memory).
Memory processes are localized
 We know which parts of the
brain are responsible for
memory
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PET scans can measure important functions in
the brain such as glucose consumption and
blood flow.
They can also identify cellular changes in an
organ or tissue.
PET scans can, therefore be used to detect brain
tumors or memory disorders n Alzheimer’s
patients. In some cases this detection comes
even before patients were aware that anything
was wrong with them.
Researchers at NYU have developed a
brain-scan based computer program that
quickly and accurately measures metabolic
activity in the hippocampus. Using PET
scans and this program, they have found a
reduction in brain metabolism in the
hippocampus in the early stages of
Alzheimer’s.
In a longitudinal study, 53 healthy
participants were followed for 9 to 24
years. They found that those who
showed early signs of reduced
metabolism in the hippocampus were
associated with later development of
Alzheimer’s.
 What
other memory studies
have used MRI’s to detect a
relationship between memory
and brain activity?
Clive Wearing
 H.M.
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-Cognitive Processes
-Physiology
-Clive Wearing
-HM